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Jong Soo Ko
Graduate school of Mechanical Engineering, Pusan National University, Busan 46241, Republic of Korea

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Journal article
Published: 17 August 2021 in Sensors and Actuators A: Physical
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The development of flexible and sensitive three-axis pressure sensors is of great interest for various wearable applications, such as electronic skin, soft robotics, and health monitoring. This study aims to propose a highly sensitive and flexible pressure sensor that can measure three-axis pressure based on conductive microstructured carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS) elastomer with a simple and large-scale fabrication method that uses a polymer wet etching process. The randomly exposed CNTs on the surface using PDMS wet etching improve the sensitivity of the pressure sensors. The fabricated sensors exhibit a high sensitivity of 1.39 kPa−1 for a pressure range of 250 Pa, excellent limit of detection capability of 1.26 Pa, fast response time of within 52 ms, and high reliability of over 10,000 times of pressure loading/unloading. As an application, the pressure sensors are demonstrated using electronic skin on human fingers for the detection of the pressure levels and pattern recognition of distributed pressure. Moreover, to measure the three-axis pressure, pressurization tests are conducted using artificial fingers, demonstrating that the fabricated sensor can successfully measure the pressures applied along the three axes.

ACS Style

Young Jung; Kyung Kuk Jung; Dong Hwan Kim; Dong Hwa Kwak; Seokyoung Ahn; Jeong Sam Han; Jong Soo Ko. Flexible and highly sensitive three-axis pressure sensors based on carbon nanotube/polydimethylsiloxane composite pyramid arrays. Sensors and Actuators A: Physical 2021, 331, 113034 .

AMA Style

Young Jung, Kyung Kuk Jung, Dong Hwan Kim, Dong Hwa Kwak, Seokyoung Ahn, Jeong Sam Han, Jong Soo Ko. Flexible and highly sensitive three-axis pressure sensors based on carbon nanotube/polydimethylsiloxane composite pyramid arrays. Sensors and Actuators A: Physical. 2021; 331 ():113034.

Chicago/Turabian Style

Young Jung; Kyung Kuk Jung; Dong Hwan Kim; Dong Hwa Kwak; Seokyoung Ahn; Jeong Sam Han; Jong Soo Ko. 2021. "Flexible and highly sensitive three-axis pressure sensors based on carbon nanotube/polydimethylsiloxane composite pyramid arrays." Sensors and Actuators A: Physical 331, no. : 113034.

Regular paper
Published: 30 June 2021 in International Journal of Precision Engineering and Manufacturing-Green Technology
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In this study, a superhydrophobic nickel surface that is highly robust against repetitive rubbing is presented. We implanted carbon nanotubes (CNTs) to protect the surfaces from contacts. We show that the CNTs implanted in nickel do not easily detach from the surface and maintain superhydrophobicity despite harsh rubbing (40 kPa, 600 cycles) by 800 grit sandpaper; by contrast, surfaces prepared by typical nanofabrication methods are visibly damaged and lose superhydrophobicity after such treatment. The CNT-implanted nickel surfaces developed in this study are the most robust among nanostructured surfaces reported up to date.

ACS Style

Kyung Kuk Jung; Young Jung; Byung-Geon Park; Chang Jun Choi; Jong Soo Ko. Super Wear Resistant Nanostructured Superhydrophobic Surface. International Journal of Precision Engineering and Manufacturing-Green Technology 2021, 1 -13.

AMA Style

Kyung Kuk Jung, Young Jung, Byung-Geon Park, Chang Jun Choi, Jong Soo Ko. Super Wear Resistant Nanostructured Superhydrophobic Surface. International Journal of Precision Engineering and Manufacturing-Green Technology. 2021; ():1-13.

Chicago/Turabian Style

Kyung Kuk Jung; Young Jung; Byung-Geon Park; Chang Jun Choi; Jong Soo Ko. 2021. "Super Wear Resistant Nanostructured Superhydrophobic Surface." International Journal of Precision Engineering and Manufacturing-Green Technology , no. : 1-13.

Journal article
Published: 08 March 2021 in Polymers
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Highly flexible and compressible porous polyurethane (PU) structures have effectively been applied in capacitive pressure sensors because of the good elastic properties of the PU structures. However, PU porous structure-based pressure sensors have been limited in practical applications owing to their low durability during pressure cycling. Herein, we report a flexible pressure sensor based on a three-dimensional porous structure with notable durability at a compressive pressure of 500 kPa facilitated by the use of a shape memory polymer (SMP). The SMP porous structure was fabricated using a sugar templating process and capillary effect. The use of the SMP resulted in the maintenance of the sensing performance for 100 cycles at 500 kPa; the SMP can restore its original shape within 30 s of heating at 80 °C. The pressure sensor based on the SMP exhibited a higher sensitivity of 0.0223 kPa−1 than a typical PU-based sensor and displayed excellent sensing performance in terms of stability, response time, and hysteresis. Additionally, the proposed sensor was used to detect shoe insole pressures in real time and exhibited remarkable durability and motion differentiation.

ACS Style

Byunggeon Park; Young Jung; Jong Ko; Jinhyoung Park; Hanchul Cho. Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer. Polymers 2021, 13, 824 .

AMA Style

Byunggeon Park, Young Jung, Jong Ko, Jinhyoung Park, Hanchul Cho. Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer. Polymers. 2021; 13 (5):824.

Chicago/Turabian Style

Byunggeon Park; Young Jung; Jong Ko; Jinhyoung Park; Hanchul Cho. 2021. "Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer." Polymers 13, no. 5: 824.

Journal article
Published: 05 July 2020 in Polymers
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We developed a simple, low-cost process to fabricate a flexible pressure sensor with linear sensitivity by using a porous carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite structure (CPCS). The working principle of this pressure sensor is based on the change in electrical resistance caused by the contact/non-contact of the CNT tip on the surface of the pores under pressure. The mechanical and electrical properties of the CPCSs could be quantitatively controlled by adjusting the concentration of CNTs. The fabricated flexible pressure sensor showed linear sensitivity and excellent performance with regard to repeatability, hysteresis, and reliability. Furthermore, we showed that the sensor could be applied for human motion detection, even when attached to curved surfaces.

ACS Style

Young Jung; Kyung Kuk Jung; Dong Hwan Kim; Dong Hwa Kwak; Jong Soo Ko. Linearly Sensitive and Flexible Pressure Sensor Based on Porous Carbon Nanotube/Polydimethylsiloxane Composite Structure. Polymers 2020, 12, 1499 .

AMA Style

Young Jung, Kyung Kuk Jung, Dong Hwan Kim, Dong Hwa Kwak, Jong Soo Ko. Linearly Sensitive and Flexible Pressure Sensor Based on Porous Carbon Nanotube/Polydimethylsiloxane Composite Structure. Polymers. 2020; 12 (7):1499.

Chicago/Turabian Style

Young Jung; Kyung Kuk Jung; Dong Hwan Kim; Dong Hwa Kwak; Jong Soo Ko. 2020. "Linearly Sensitive and Flexible Pressure Sensor Based on Porous Carbon Nanotube/Polydimethylsiloxane Composite Structure." Polymers 12, no. 7: 1499.

Journal article
Published: 24 June 2020 in Polymers
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In recent times, polymer-based flexible pressure sensors have been attracting a lot of attention because of their various applications. A highly sensitive and flexible sensor is suggested, capable of being attached to the human body, based on a three-dimensional dielectric elastomeric structure of polydimethylsiloxane (PDMS) and microsphere composite. This sensor has maximal porosity due to macropores created by sacrificial layer grains and micropores generated by microspheres pre-mixed with PDMS, allowing it to operate at a wider pressure range (~150 kPa) while maintaining a sensitivity (of 0.124 kPa−1 in a range of 0~ 15 kPa) better than in previous studies. The maximized pores can cause deformation in the structure, allowing for the detection of small changes in pressure. In addition to exhibiting a fast rise time (~167 ms) and fall time (~117 ms), as well as excellent reproducibility, the fabricated pressure sensor exhibits reliability in its response to repeated mechanical stimuli (2.5 kPa, 1,000 cycles). As an application, we develop a wearable device for monitoring repeated tiny motions, such as the pulse on the human neck and swallowing at the Adam’s apple. This sensory device is also used to detect movements in the index finger and to monitor an insole system in real-time.

ACS Style

Young Jung; Wookjin Lee; Kyungkuk Jung; Byunggeon Park; Jinhyoung Park; Jongsoo Ko; Hanchul Cho. A Highly Sensitive and Flexible Capacitive Pressure Sensor Based on a Porous Three-Dimensional PDMS/Microsphere Composite. Polymers 2020, 12, 1412 .

AMA Style

Young Jung, Wookjin Lee, Kyungkuk Jung, Byunggeon Park, Jinhyoung Park, Jongsoo Ko, Hanchul Cho. A Highly Sensitive and Flexible Capacitive Pressure Sensor Based on a Porous Three-Dimensional PDMS/Microsphere Composite. Polymers. 2020; 12 (6):1412.

Chicago/Turabian Style

Young Jung; Wookjin Lee; Kyungkuk Jung; Byunggeon Park; Jinhyoung Park; Jongsoo Ko; Hanchul Cho. 2020. "A Highly Sensitive and Flexible Capacitive Pressure Sensor Based on a Porous Three-Dimensional PDMS/Microsphere Composite." Polymers 12, no. 6: 1412.

Journal article
Published: 01 March 2020 in AIP Advances
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In this study, we report a simple alignment method to align silver nanowires (Ag NWs) using a dip-coating technique while controlling the temperature of glass substrate and Ag NW dispersion. It is found that the structural anisotropy and transmittance characteristics of the substrate lined with the Ag NWs depend on the temperature of the dispersion and substrate and the withdrawal velocity. The maximum structural anisotropy of the aligned Ag NWs was 0.947 at a withdrawal velocity of 1.0 mm/s and a temperature of 80 °C. In addition, a glass substrate with the aligned Ag NWs shows a high transmittance of 96.7% at the sheet resistance of 22 Ω/sq.In this study, we report a simple alignment method to align silver nanowires (Ag NWs) using a dip-coating technique while controlling the temperature of glass substrate and Ag NW dispersion. It is found that the structural anisotropy and transmittance characteristics of the substrate lined with the Ag NWs depend on the temperature of the dispersion and substrate and the withdrawal velocity. The maximum structural anisotropy of the aligned Ag NWs was 0.947 at a withdrawal velocity of 1.0 mm/s and a temperature of 80 °C. In addition, a glass substrate with the aligned Ag NWs shows a high transmittance of 96.7% at the sheet resistance of 22 Ω/sq.

ACS Style

M. G. Shin; C. J. Choi; Y. Jung; J. H. Choi; J. S. Ko. Alignment of silver nanowires using heat-assisted dip-coating method. AIP Advances 2020, 10, 035101 .

AMA Style

M. G. Shin, C. J. Choi, Y. Jung, J. H. Choi, J. S. Ko. Alignment of silver nanowires using heat-assisted dip-coating method. AIP Advances. 2020; 10 (3):035101.

Chicago/Turabian Style

M. G. Shin; C. J. Choi; Y. Jung; J. H. Choi; J. S. Ko. 2020. "Alignment of silver nanowires using heat-assisted dip-coating method." AIP Advances 10, no. 3: 035101.

Journal article
Published: 30 January 2020 in Micromachines
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In this study, we fabricated strain sensors by aligning silver nanowires and transferring them with polydimethylsiloxane (PDMS) and compared the performances of the fabricated strain sensors along the alignment direction. Two types of flexible strain sensors embedded with the aligned silver nanowires were fabricated: one in the longitudinal direction, which is the same as the alignment direction, and the other in the lateral direction, which is perpendicular to the alignment direction. We then evaluated their properties. The proposed longitudinally aligned strain sensor showed the maximum sensitivity (gauge factor (GF) = 89.99) under 25% tensile conditions, which is 7.08 times higher than the sensitivity (GF = 12.71) shown by the laterally aligned strain sensor under 25% tensile conditions. This finding confirmed that the alignment direction of silver nanowires influences the sensitivity of flexible strain sensors. Furthermore, this study demonstrates that the laterally aligned strain sensor (ε > 60%) can be used in wearable devices because it satisfies the required strain range (ε > 50%). Since the strain sensors were fabricated using the temperature-controlled dip coating process, they can be produced at low cost in large quantities, and thus they have advantages for commercialization. These characteristics will be applicable to various flexible devices as well as to flexible strain sensors.

ACS Style

Jae Hyuk Choi; Myung Gyu Shin; Young Jung; Dong Hwan Kim; Jong Soo Ko. Fabrication and Performance Evaluation of Highly Sensitive Flexible Strain Sensors with Aligned Silver Nanowires. Micromachines 2020, 11, 156 .

AMA Style

Jae Hyuk Choi, Myung Gyu Shin, Young Jung, Dong Hwan Kim, Jong Soo Ko. Fabrication and Performance Evaluation of Highly Sensitive Flexible Strain Sensors with Aligned Silver Nanowires. Micromachines. 2020; 11 (2):156.

Chicago/Turabian Style

Jae Hyuk Choi; Myung Gyu Shin; Young Jung; Dong Hwan Kim; Jong Soo Ko. 2020. "Fabrication and Performance Evaluation of Highly Sensitive Flexible Strain Sensors with Aligned Silver Nanowires." Micromachines 11, no. 2: 156.

Regular paper
Published: 20 February 2019 in International Journal of Precision Engineering and Manufacturing
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The present study aimed to determine the optimum levels of experimental factors that affect electroplating performance, i.e., filling via holes without defects. To this end, the Taguchi experimental design method was employed. The uniformity of plated Cu thickness was selected as the characteristic, and experimental conditions were determined using an orthogonal matrix array with respect to the selected experimental factors. The results were analyzed based on the signal-to-noise ratios acquired from experimental measurements. When the aspect ratio was low, the concentration of a leveler was found to be the determining factor. As the aspect ratio increased, the effect of current density and pulse time became more significant.

ACS Style

Byung-Geon Park; Seon Gyeong Kim; Jong Soo Ko. A Study on the Optimization of Electroplating Conditions for Silicon Vias Using the Taguchi Experimental Design Method. International Journal of Precision Engineering and Manufacturing 2019, 20, 437 -442.

AMA Style

Byung-Geon Park, Seon Gyeong Kim, Jong Soo Ko. A Study on the Optimization of Electroplating Conditions for Silicon Vias Using the Taguchi Experimental Design Method. International Journal of Precision Engineering and Manufacturing. 2019; 20 (3):437-442.

Chicago/Turabian Style

Byung-Geon Park; Seon Gyeong Kim; Jong Soo Ko. 2019. "A Study on the Optimization of Electroplating Conditions for Silicon Vias Using the Taguchi Experimental Design Method." International Journal of Precision Engineering and Manufacturing 20, no. 3: 437-442.

Letter
Published: 11 January 2019 in Micro and Nano Systems Letters
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This paper investigates the change of the relative magnitudes of force and impulse components generated by the rotational motion of a hydrophobic carbon rod moving into water from the water surface, by varying the rod length. Whereas added mass force and drag force were dominant regardless of the rod length, buoyancy force and surface tension force were relatively small. For relatively short rod lengths (2, 4, 6 cm), drag forces were larger than added mass forces in the beginning of the rotational motion; the magnitudes of the two forces, however, reversed during the rotation. It was found that the reversals of magnitudes of the two forces occurred when the velocity at the end of the rod was 0.5 m/s. On the other hand, for a long rod length of 8 cm, added mass force was higher than drag force throughout the rod motion. The change of impulse by varying the rod length showed a similar tendency to that of force. Added mass impulse and drag impulse were also considerably larger than buoyancy impulse and surface tension impulse. Furthermore, drag impulse was larger than added mass impulse for short rod lengths, and the magnitudes of the two impulses reversed for long rod lengths. Compared to the shorter rod, the larger rod has a relatively low momentary force, but its force has much larger duration time, resulting in an increase of impulse.

ACS Style

Sun Gi Park; Min Chul Lee; Hyeong Jun Tak; Jong Soo Ko. Analysis of force and impulse of a hydrophobic rod rotating into water. Micro and Nano Systems Letters 2019, 7, 1 .

AMA Style

Sun Gi Park, Min Chul Lee, Hyeong Jun Tak, Jong Soo Ko. Analysis of force and impulse of a hydrophobic rod rotating into water. Micro and Nano Systems Letters. 2019; 7 (1):1.

Chicago/Turabian Style

Sun Gi Park; Min Chul Lee; Hyeong Jun Tak; Jong Soo Ko. 2019. "Analysis of force and impulse of a hydrophobic rod rotating into water." Micro and Nano Systems Letters 7, no. 1: 1.

Research article
Published: 10 October 2018 in ACS Omega
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We propose a new superhydrophobic surface that contains a carbon nanotube (CNT)-implanted poly(dimethylsiloxane) (PDMS)/adhesive multilayer. The adhesive provides very strong adhesion between the CNT-implanted PDMS layer and the substrate, and the CNTs on the surface exhibit superhydrophobicity. Therefore, the CNT-implanted PDMS/adhesive (CIPA) layer provides a highly reliable surface for superhydrophobicity. The fabricated CIPA surface performs far better than previously reported surfaces in terms of stability tests, such as contamination and solvent tests, and physical contact, including thermal pressure, bending, adhesion, and water jet tests. If a portion of the CIPA surface is destroyed, the surface is immediately restored because the material can regenerate the surface to its initial state. The surface can therefore maintain its superhydrophobicity even when damaged in rough environments, without self-healing or additional repair. Furthermore, because the adhesive is sprayed and coated on the surface of the substrate, a CIPA surface can be formed on three-dimensional shapes, including curved surfaces, and on various substrates.

ACS Style

Kyung Kuk Jung; Young Jung; Chang Jun Choi; Jong Soo Ko. Highly Reliable Superhydrophobic Surface with Carbon Nanotubes Immobilized on a PDMS/Adhesive Multilayer. ACS Omega 2018, 3, 12956 -12966.

AMA Style

Kyung Kuk Jung, Young Jung, Chang Jun Choi, Jong Soo Ko. Highly Reliable Superhydrophobic Surface with Carbon Nanotubes Immobilized on a PDMS/Adhesive Multilayer. ACS Omega. 2018; 3 (10):12956-12966.

Chicago/Turabian Style

Kyung Kuk Jung; Young Jung; Chang Jun Choi; Jong Soo Ko. 2018. "Highly Reliable Superhydrophobic Surface with Carbon Nanotubes Immobilized on a PDMS/Adhesive Multilayer." ACS Omega 3, no. 10: 12956-12966.

Regular paper
Published: 20 April 2018 in International Journal of Precision Engineering and Manufacturing-Green Technology
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In this study, we designed and fabricated a capacitive oil detector using a polydimethyl siloxane (PDMS) sponge and evaluated its performance. A PDMS sponge has a hydrophobic/oleophilic characteristic, which blocks water infiltration yet absorbs oil. The absorbed oil changes the detector capacitance between the two electrodes within the PDMS sponge. We used three primary types of marine fuel oils (diesel, crude oil, and heavy oil) to evaluate the performance of the fabricated oil detector. Diesel was detected in the shortest time, followed by crude oil and heavy oil. That is, oils with lower viscosity were detected more rapidly. The measured capacitance was the lowest for diesel and the highest for heavy oil. Oils with higher dielectric constants had a higher measured capacitance. Water did not seep into the microcavity of the capacitive oil detector until it reached a depth of 140 cm. We were able to detect the presence of an oil-film below 900 μm. The fabricated detector showed almost the same capacitance throughout the ten cycles of repeated cleaning and measurements.

ACS Style

Young Jung; Kyung Kuk Jung; Byung Geon Park; Jong Soo Ko. Capacitive Oil Detector Using Hydrophobic and Oleophilic PDMS Sponge. International Journal of Precision Engineering and Manufacturing-Green Technology 2018, 5, 303 -309.

AMA Style

Young Jung, Kyung Kuk Jung, Byung Geon Park, Jong Soo Ko. Capacitive Oil Detector Using Hydrophobic and Oleophilic PDMS Sponge. International Journal of Precision Engineering and Manufacturing-Green Technology. 2018; 5 (2):303-309.

Chicago/Turabian Style

Young Jung; Kyung Kuk Jung; Byung Geon Park; Jong Soo Ko. 2018. "Capacitive Oil Detector Using Hydrophobic and Oleophilic PDMS Sponge." International Journal of Precision Engineering and Manufacturing-Green Technology 5, no. 2: 303-309.

Research article
Published: 14 February 2018 in ACS Applied Materials & Interfaces
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Triplet–triplet annihilation upconversion (TTA-UC) has recently drawn widespread interest for its capacity to harvest low-energy photons and to broaden the absorption spectra of photonic devices such as solar cells. Although conceptually promising, effective integration of TTA-UC materials into practical devices has been difficult due to the diffusive and anoxic conditions required in TTA-UC host media. Of the solid-state host materials investigated, rubbery polymers facilitate the highest TTA-UC efficiencies. To date, however, their need for long-term oxygen protection has limited rubbery polymers to rigid film architectures that forfeit their intrinsic flexibility. This study introduces a new multilayer thin film architecture in which scalable solution processing techniques are employed to fabricate flexible, photostable, and efficient TTA-UC thin films containing layers of oxygen barrier and host polymers. This breakthrough material design marks a crucial advance toward TTA-UC integration within rigid and flexible devices alike. Moreover, it introduces new opportunities in unexplored applications such as anti-counterfeiting. Soft lithography is incorporated into the film fabrication process to pattern TTA-UC host layers with a broad range of high-resolution microscale designs, and superimposing host layers with customized absorption, emission, and patterning ultimately produces proof-of-concept anti-counterfeiting labels with advanced excitation-dependent photoluminescent security features.

ACS Style

Anna L. Hagstrom; Hak-Lae Lee; Myung-Soo Lee; Hyun-Seok Choe; Joori Jung; Byung-Geon Park; Won-Sik Han; Jong Soo Ko; Jae-Hong Kim; Jae-Hyuk Kim. Flexible and Micropatternable Triplet–Triplet Annihilation Upconversion Thin Films for Photonic Device Integration and Anticounterfeiting Applications. ACS Applied Materials & Interfaces 2018, 10, 8985 -8992.

AMA Style

Anna L. Hagstrom, Hak-Lae Lee, Myung-Soo Lee, Hyun-Seok Choe, Joori Jung, Byung-Geon Park, Won-Sik Han, Jong Soo Ko, Jae-Hong Kim, Jae-Hyuk Kim. Flexible and Micropatternable Triplet–Triplet Annihilation Upconversion Thin Films for Photonic Device Integration and Anticounterfeiting Applications. ACS Applied Materials & Interfaces. 2018; 10 (10):8985-8992.

Chicago/Turabian Style

Anna L. Hagstrom; Hak-Lae Lee; Myung-Soo Lee; Hyun-Seok Choe; Joori Jung; Byung-Geon Park; Won-Sik Han; Jong Soo Ko; Jae-Hong Kim; Jae-Hyuk Kim. 2018. "Flexible and Micropatternable Triplet–Triplet Annihilation Upconversion Thin Films for Photonic Device Integration and Anticounterfeiting Applications." ACS Applied Materials & Interfaces 10, no. 10: 8985-8992.

Regular paper
Published: 07 June 2017 in International Journal of Precision Engineering and Manufacturing
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This paper reports the effects of the stirring rate of the solution, boric acid concentration, and applied current density on the formation of the copper-cuprous co-electrodeposited structure. For copper-cuprous co-electrodeposition, 0.5 M CuSO4·5H2O solution was used. When electrodeposition was performed via stirring and the addition of boric acid, pillar-type electrodeposited structures were formed. On the other hand, when electrodeposition was carried out without stirring or the addition of boric acid, hill-type electrodeposited structures were formed. Development of the pillar structure was promoted by increasing the boric acid concentration and the stirring rate. The electrodeposited structure was applied to surface modification in order to verify its industrial effectiveness. When the concentration of the added boric acid was higher than 0.5 M and the stirring rate of the solution was 200 rpm, the fabricated specimens showed superhydrophobic properties after hydrophobic layer coating.

ACS Style

Jae Min Lee; Jong Soo Ko. Formation of microstructure by copper-cuprous co-electrodeposition using stirring and boric acid addition. International Journal of Precision Engineering and Manufacturing 2017, 18, 871 -877.

AMA Style

Jae Min Lee, Jong Soo Ko. Formation of microstructure by copper-cuprous co-electrodeposition using stirring and boric acid addition. International Journal of Precision Engineering and Manufacturing. 2017; 18 (6):871-877.

Chicago/Turabian Style

Jae Min Lee; Jong Soo Ko. 2017. "Formation of microstructure by copper-cuprous co-electrodeposition using stirring and boric acid addition." International Journal of Precision Engineering and Manufacturing 18, no. 6: 871-877.

Journal article
Published: 13 April 2016 in Journal of Mechanical Science and Technology
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In this research, an accelerometer with an over-range stopper was designed, fabricated and evaluated. When a shock beyond the sensing range is applied to an acceleration sensor, an over-range stopper limits the amount of longitudinal deformation in the sensing bridge, which is weak to shocks, below a certain level and so prevents the acceleration sensor from breaking. To analyze the effect of the overrange stopper shape on acceleration sensor performance, we fabricated high-shock accelerometers with over-range stoppers of three different lengths (short, medium and long models). We then performed a comparative analysis of the performance of each accelerometer.

ACS Style

Jae Min Lee; Chang Uk Jang; Chang Jun Choi; Ki Beom Kwon; Jeong Sam Han; Nam Yeol Kwon; Jong Soo Ko. High-shock silicon accelerometer with an over-range stopper. Journal of Mechanical Science and Technology 2016, 30, 1817 -1824.

AMA Style

Jae Min Lee, Chang Uk Jang, Chang Jun Choi, Ki Beom Kwon, Jeong Sam Han, Nam Yeol Kwon, Jong Soo Ko. High-shock silicon accelerometer with an over-range stopper. Journal of Mechanical Science and Technology. 2016; 30 (4):1817-1824.

Chicago/Turabian Style

Jae Min Lee; Chang Uk Jang; Chang Jun Choi; Ki Beom Kwon; Jeong Sam Han; Nam Yeol Kwon; Jong Soo Ko. 2016. "High-shock silicon accelerometer with an over-range stopper." Journal of Mechanical Science and Technology 30, no. 4: 1817-1824.

Journal article
Published: 30 November 2015 in Journal of Materials Science
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This research investigated the fabrication of pillar-type nickel nanostructures by using an electrodeposition solution containing NaCl. When nickel electrodeposition was performed using the NaCl-containing electrodeposition solution, the growth of the electrodeposition structure in the (200) crystal direction was restricted, whereas that in the (111) crystal direction was promoted. Accordingly, when electrodeposition was performed using the NaCl-containing electrodeposition solution, an anisotropic, pillar-shaped electrodeposition structure was formed. A sharper pillar structure was formed with increasing concentration of NaCl added to the electrodeposition solution. Additionally, it was confirmed that a specimen manufactured using electrodeposition solution containing NaCl of 2 M or higher had a superhydrophobic surface after surface treatment.

ACS Style

Jae Min Lee; Kyung Kuk Jung; Jong Soo Ko. Effect of NaCl in a nickel electrodeposition on the formation of nickel nanostructure. Journal of Materials Science 2015, 51, 3036 -3044.

AMA Style

Jae Min Lee, Kyung Kuk Jung, Jong Soo Ko. Effect of NaCl in a nickel electrodeposition on the formation of nickel nanostructure. Journal of Materials Science. 2015; 51 (6):3036-3044.

Chicago/Turabian Style

Jae Min Lee; Kyung Kuk Jung; Jong Soo Ko. 2015. "Effect of NaCl in a nickel electrodeposition on the formation of nickel nanostructure." Journal of Materials Science 51, no. 6: 3036-3044.

Journal article
Published: 28 March 2015 in Applied Physics A
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In this paper, the mechanism of micropore structures generated inside PP (polypropylene) polymer due to thermal shock propagation caused by a pulsed laser was studied. When a thermal shock wave radiated to the PP film, a stress shock wave was transmitted to the interior. When both the appropriate absorption coefficient of thermoplastic polymer and the rapid pressure drop were provided, micropores were generated due to the crystallization of PP and decrease in viscosity. The micropores generated inside PP film with a low absorption coefficient were observed by employing a copper plate as a heat-transfer medium. The thickness of the PP film and the wavelength of the UV-pulsed laser used in this experiment were 50 µm and 355 nm, respectively.

ACS Style

Moon Suk Kang; Jong Soo Ko; Sang Mae Lee; Bo Sung Shin. Fundamental study of direct microporous process using laser shock wave. Applied Physics A 2015, 119, 439 -444.

AMA Style

Moon Suk Kang, Jong Soo Ko, Sang Mae Lee, Bo Sung Shin. Fundamental study of direct microporous process using laser shock wave. Applied Physics A. 2015; 119 (3):439-444.

Chicago/Turabian Style

Moon Suk Kang; Jong Soo Ko; Sang Mae Lee; Bo Sung Shin. 2015. "Fundamental study of direct microporous process using laser shock wave." Applied Physics A 119, no. 3: 439-444.

Article
Published: 01 April 2014 in Journal of Mechanical Science and Technology
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A high-shock 2000 g accelerometer with suspended piezoresistive sensing bridges has been designed, fabricated, and tested. Structural size of the accelerometer has been obtained through an optimal design process. Four resistors are electrically connected to form a Wheatstone bridge circuit. A sensitivity of 25.5 μV/g has been measured from the fabricated accelerometer with a nonlinearity of 0.2% in an acceleration range within 2000 g. The real-time response of the fabricated accelerometers accurately follows the reference accelerometer. The newly fabricated accelerometer has survived an over-shock condition of 4667 g.

ACS Style

Kong Myeong Bae; Jae Min Lee; Ki Beom Kwon; Ki-Ho Han; Nam Yeol Kwon; Jeong Sam Han; Jong Soo Ko. High-shock silicon accelerometer with suspended piezoresistive sensing bridges. Journal of Mechanical Science and Technology 2014, 28, 1449 -1454.

AMA Style

Kong Myeong Bae, Jae Min Lee, Ki Beom Kwon, Ki-Ho Han, Nam Yeol Kwon, Jeong Sam Han, Jong Soo Ko. High-shock silicon accelerometer with suspended piezoresistive sensing bridges. Journal of Mechanical Science and Technology. 2014; 28 (4):1449-1454.

Chicago/Turabian Style

Kong Myeong Bae; Jae Min Lee; Ki Beom Kwon; Ki-Ho Han; Nam Yeol Kwon; Jeong Sam Han; Jong Soo Ko. 2014. "High-shock silicon accelerometer with suspended piezoresistive sensing bridges." Journal of Mechanical Science and Technology 28, no. 4: 1449-1454.

Short communication
Published: 15 August 2012 in Materials Letters
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We observed the variation in the size of microwrinkles according to the number of unit processing cycles, which consist of polydimethyl siloxane (PDMS) casting followed by the deposition of Al. As the number of processing cycles increases, the width of the microwrinkles narrows and their height increases. After five processing cycles were completed, the width of the microwrinkles stood at 1.7–3.7 μm. The top surface area of the microwrinkles became smaller upon additional processing cycles, thereby reducing the contact area between the water drops and the top surface. For this reason, the contact angle increased as the number of processing cycles increased. The contact angle measured after five processing cycles was 145°, implying that the microwrinkled surface was modified such that it became superhydrophobic.

ACS Style

Eunbi Seo; Seung-Hwan Lee; Bo Sung Shin; Won Ick Jang; Jong Soo Ko. Microwrinkles by deposition of aluminum onto polydimethylsiloxane. Materials Letters 2012, 81, 119 -122.

AMA Style

Eunbi Seo, Seung-Hwan Lee, Bo Sung Shin, Won Ick Jang, Jong Soo Ko. Microwrinkles by deposition of aluminum onto polydimethylsiloxane. Materials Letters. 2012; 81 ():119-122.

Chicago/Turabian Style

Eunbi Seo; Seung-Hwan Lee; Bo Sung Shin; Won Ick Jang; Jong Soo Ko. 2012. "Microwrinkles by deposition of aluminum onto polydimethylsiloxane." Materials Letters 81, no. : 119-122.

Journal article
Published: 31 January 2012 in Biomaterials
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Topographical features are known to physically affect cell behavior and are expected to have great potential for non-invasive control of such behavior. To provide a design concept of a microstructured surface for elaborate non-invasive control of cell migration, we systematically analyzed the effect of microgrooves on cell migration. We fabricated silicon microstructured surfaces covered with SiO2 with microgrooves of various sizes, and characterized the behavior of cells moving from the flat surface to the grooved surface. The intersecting microgrooves with well-defined groove width absorbed or repelled cells precisely according to the angle of approach of the cell to the boundary with the grooved surface. This filtering process was explained by the difference in the magnitude of the lamellar dragging effect resulting from the number of the grooves interacting with the lamella of the cell. This study provides a framework to tailor the microgrooved surface for non-invasive control of cell migration with label-free detection of a specific property of the target cells. This should offer significant benefits to biomedical research and applications.

ACS Style

Hiromi Miyoshi; Taiji Adachi; Jungmyoung Ju; Sang Min Lee; Dong Jin Cho; Jong Soo Ko; Go Uchida; Yutaka Yamagata. Characteristics of motility-based filtering of adherent cells on microgrooved surfaces. Biomaterials 2012, 33, 395 -401.

AMA Style

Hiromi Miyoshi, Taiji Adachi, Jungmyoung Ju, Sang Min Lee, Dong Jin Cho, Jong Soo Ko, Go Uchida, Yutaka Yamagata. Characteristics of motility-based filtering of adherent cells on microgrooved surfaces. Biomaterials. 2012; 33 (2):395-401.

Chicago/Turabian Style

Hiromi Miyoshi; Taiji Adachi; Jungmyoung Ju; Sang Min Lee; Dong Jin Cho; Jong Soo Ko; Go Uchida; Yutaka Yamagata. 2012. "Characteristics of motility-based filtering of adherent cells on microgrooved surfaces." Biomaterials 33, no. 2: 395-401.

Journal article
Published: 30 November 2011 in Sensors and Actuators A: Physical
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A superhydrophobic micromesh covered with nanoprotrusions has been introduced and its applicability to a waterproof mobile phone speaker has been evaluated. The nanotextured superhydrophobic micromesh showed excellent water repellency, self-cleaning and waterproofing performances. In a waterproof speaker test using the fabricated nanotextured micromesh, the micromesh did not lose its waterproof function at 2 m water depth and did not form a remnant water film after being removed from the water. The packaged speaker showed almost the same sound quality before and after dipping at a 2 m water depth. These results demonstrate that the superhydrophobic nanotextured micromesh could be directly applicable for various products that need to resist water penetration, yet allow the transmission of gases and sound/light waves.

ACS Style

Sang Min Lee; Jae Hwa Song; Phill Gu Jung; Dong Hyo Jang; Min Seong Kim; Weui Bong Jeong; Byung Min Kim; Jong Soo Ko. Nanotextured superhydrophobic micromesh. Sensors and Actuators A: Physical 2011, 171, 233 -240.

AMA Style

Sang Min Lee, Jae Hwa Song, Phill Gu Jung, Dong Hyo Jang, Min Seong Kim, Weui Bong Jeong, Byung Min Kim, Jong Soo Ko. Nanotextured superhydrophobic micromesh. Sensors and Actuators A: Physical. 2011; 171 (2):233-240.

Chicago/Turabian Style

Sang Min Lee; Jae Hwa Song; Phill Gu Jung; Dong Hyo Jang; Min Seong Kim; Weui Bong Jeong; Byung Min Kim; Jong Soo Ko. 2011. "Nanotextured superhydrophobic micromesh." Sensors and Actuators A: Physical 171, no. 2: 233-240.