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The energy requirements of a solar-powered exploration rover constrain the mission duration, traversability, and tractive capability under the given limited usable power. Thus, exploration rover design, more specifically, rover wheel design (related to considerable energy consumption in driving), plays a significant role in the success of exploration missions. This paper describes the modeling of an operational environment and a multi-body dynamics (MBD) simulation tool based on wheel-terrain interaction model to predict the dynamic behavior on a digital elevation model (DEM) map. With these simulation environments, a multidisciplinary optimal wheel design methodology, integrating the MBD simulation tool and non-dominated sorting genetic algorithm-II (NSGA-II), is developed. Design parameters are chosen through sensitivity analysis. These multi-objective optimizations in dynamic states are conducted to obtain the optimal wheel dimension that meet the limited power condition with maximal tractive capability under the given operational environment. Furthermore, numerical and experimental verification using a single wheel testbed on lunar simulant are conducted to convincingly validate the derived optimization results. Finally, these results reveal that the proposed design methodology is an effective approach to deciding the best design parameter among a large variety of candidate design points considering the restricted power requirement.
Kun-Jung Kim; Kee-Ho Yu. Multidisciplinary Design Optimization for a Solar-Powered Exploration Rover Considering the Restricted Power Requirement. Energies 2020, 13, 6652 .
AMA StyleKun-Jung Kim, Kee-Ho Yu. Multidisciplinary Design Optimization for a Solar-Powered Exploration Rover Considering the Restricted Power Requirement. Energies. 2020; 13 (24):6652.
Chicago/Turabian StyleKun-Jung Kim; Kee-Ho Yu. 2020. "Multidisciplinary Design Optimization for a Solar-Powered Exploration Rover Considering the Restricted Power Requirement." Energies 13, no. 24: 6652.
Communication is a key aspect in modern life. Unfortunately, when natural disasters occur, the communication system and infrastructure of a city can be partially lost, and in the worst case, completely destroyed. In this case, communication is a crucial part for the search-and-rescue missions. This paper focuses on developing an aerial communication relay platform as an effective solution for communication loss in a natural disaster. The model used considers the aircraft altitude and attitude, which affects the energy acquisition and consumption, and the signal fading effects. The flight path planning is performed adopting a nonlinear optimization technique, Hermite-Simpson collocation method. For a realistic communication model regarding urban signal loss and path propagation, the building deployment of a 2km radius circular area of two cities in South Korea (Seoul and Jeonju) was obtained. Simulation experiments for the different urban environments are performed to test the communication reliability focusing on the relation between the Unmanned Aerial Vehicle (UAV) and the Ground Users (GU). As a result of the simulation, an optimal flight path in a high-rise urban and urban microcell environment is obtained. The flight path indicates the feasibility of endurance flights for low-altitude communication aid aircrafts including signal fading model alongside solar power energy acquisition into the case study.
Giancarlo Eder Guerra Padilla; Kun-Jung Kim; Seok-Hwan Park; Kee-Ho Yu. Flight Path Planning of Solar-Powered UAV for Sustainable Communication Relay. IEEE Robotics and Automation Letters 2020, 5, 6772 -6779.
AMA StyleGiancarlo Eder Guerra Padilla, Kun-Jung Kim, Seok-Hwan Park, Kee-Ho Yu. Flight Path Planning of Solar-Powered UAV for Sustainable Communication Relay. IEEE Robotics and Automation Letters. 2020; 5 (4):6772-6779.
Chicago/Turabian StyleGiancarlo Eder Guerra Padilla; Kun-Jung Kim; Seok-Hwan Park; Kee-Ho Yu. 2020. "Flight Path Planning of Solar-Powered UAV for Sustainable Communication Relay." IEEE Robotics and Automation Letters 5, no. 4: 6772-6779.
Joon-Sung Lee; Young-Seok Kim; Kun-Jung Kim; Kee-Ho Yu. Design of Field-Driving Robot with Variable Wheel Mechanism. Journal of Korea Robotics Society 2019, 14, 186 -190.
AMA StyleJoon-Sung Lee, Young-Seok Kim, Kun-Jung Kim, Kee-Ho Yu. Design of Field-Driving Robot with Variable Wheel Mechanism. Journal of Korea Robotics Society. 2019; 14 (3):186-190.
Chicago/Turabian StyleJoon-Sung Lee; Young-Seok Kim; Kun-Jung Kim; Kee-Ho Yu. 2019. "Design of Field-Driving Robot with Variable Wheel Mechanism." Journal of Korea Robotics Society 14, no. 3: 186-190.
Achieving the long-endurance of a solar-powered unmanned aerial vehicle is difficult under a limited amount of energy and specific meteorological environments. Therefore, it is essential to manage the energy used by a solar-powered UAV during a mission. In this study, a framework for energy-based path planning for a solar-powered UAV is presented. In order to generate the optimal path in terms of energy in a specific meteorological environment, the energy model of a solar-powered UAV is considered with regard to wind field. Additionally, the optimal energy path is examined through the optimal control technique. The optimal path is then applied to some case studies regarding solar-powered UAVs, and evaluated in order to verify the feasibility of the proposed approach. The optimization results show that the resulting path is indeed the optimal path, which increases the endurance of a flight and takes weather conditions into accounts. The proposed approach is also expected to find optimal paths in accordance with real weather environments and/or various weather situations.
Seong-Hwan Kim; Giancarlo Eder Guerra Padilla; Kun-Jung Kim; Kee-Ho Yu. Flight Path Planning for a Solar Powered UAV in Wind Fields Using Direct Collocation. IEEE Transactions on Aerospace and Electronic Systems 2019, 56, 1094 -1105.
AMA StyleSeong-Hwan Kim, Giancarlo Eder Guerra Padilla, Kun-Jung Kim, Kee-Ho Yu. Flight Path Planning for a Solar Powered UAV in Wind Fields Using Direct Collocation. IEEE Transactions on Aerospace and Electronic Systems. 2019; 56 (2):1094-1105.
Chicago/Turabian StyleSeong-Hwan Kim; Giancarlo Eder Guerra Padilla; Kun-Jung Kim; Kee-Ho Yu. 2019. "Flight Path Planning for a Solar Powered UAV in Wind Fields Using Direct Collocation." IEEE Transactions on Aerospace and Electronic Systems 56, no. 2: 1094-1105.
Electronic Travel Aids (ETAs) improve the mobility of visually-impaired persons, but it is not easy to develop an ETA satisfying all the factors needed for reliable object detection, effective notification, and actual usability. In this study, the authors developed an easy-to-use ETA having the function of reliable object detection and its successful feedback to the user by tactile stimulation. Seven ultrasonic sensors facing in different directions detect obstacles in the walking path, while vibrators in the tactile display stimulate the hand according to the distribution of obstacles. The detection of ground drop-offs activates the electromagnetic brakes linked to the rear wheels. To verify the feasibility of the developed ETA in the outdoor environment, walking tests by blind participants were performed, and the evaluation of safety to ground drop-offs was carried out. From the experiment, the feasibility of the developed ETA was shown to be sufficient if the sensor ranges for hanging obstacle detection is improved and learning time is provided for the ETA. Finally, the light-weight and low cost ETA designed and assembled based on the evaluation of the developed ETA is introduced to show the improvement of portability and usability, and is compared with the previously developed ETAs.
Gu-Young Jeong; Kee-Ho Yu. Multi-Section Sensing and Vibrotactile Perception for Walking Guide of Visually Impaired Person. Sensors 2016, 16, 1070 .
AMA StyleGu-Young Jeong, Kee-Ho Yu. Multi-Section Sensing and Vibrotactile Perception for Walking Guide of Visually Impaired Person. Sensors. 2016; 16 (7):1070.
Chicago/Turabian StyleGu-Young Jeong; Kee-Ho Yu. 2016. "Multi-Section Sensing and Vibrotactile Perception for Walking Guide of Visually Impaired Person." Sensors 16, no. 7: 1070.
In this paper, the concept of a walking guide system with tactile display is introduced, and experiments of 3-D obstacle detection and tactile perception are carried out and analyzed. The algorithm of 3-D obstacle detection and the method of mapping the generated obstacle map and the tactile display device for the walking guide system are proposed. The experiment of the 3-D detection for the obstacle position using ultrasonic sensors is performed and estimated. Some design guidelines for a tactile display device that can display obstacle distribution is discussed.
Myoung-Jong Yoon; Kee-Ho Yu. 3D detection of obstacle distribution in walking guide system for the blind. International Workshop and Conference on Photonics and Nanotechnology 2007 2007, 6794, 679428 .
AMA StyleMyoung-Jong Yoon, Kee-Ho Yu. 3D detection of obstacle distribution in walking guide system for the blind. International Workshop and Conference on Photonics and Nanotechnology 2007. 2007; 6794 ():679428.
Chicago/Turabian StyleMyoung-Jong Yoon; Kee-Ho Yu. 2007. "3D detection of obstacle distribution in walking guide system for the blind." International Workshop and Conference on Photonics and Nanotechnology 2007 6794, no. : 679428.
The morphological change of ECG is the important diagnostic parameter to finding the malfunction of a heart. Accordingly, physicians make theirs effort to find the change of ST segment level, RR interval, PR interval, P wave, T wave, etc. Generally ST segment deviation and T deviation is concerned with myocardial abnormality. The aim of this study is to detect the change of ST and T in shape using a polynomial approximation method. The developed algorithm makes the least squares curve for the data between S wave and T wave in ECG and calculates the variance of ST and T shape. An approximate curve of ST is represented by one polynomial over the whole ST or three polynomials for the segmented ST by three parts. We applied the developed algorithm to the ECGs in European ST database. The algorithm detects the relative change of ST shape based on the reference ST that is the average ST about 10 ST from the beginning of test ECG. We compared the annotations checked by cardiologists with the result of our algorithm. From the results of the auto-analysis using our algorithm, we could acquire the information about the place including ST and T episode in the test ECG.
G. Y. Jeong; Kee-Ho Yu. Automatic Detection of ST and T episodes using Polynomial Approximation. VI Latin American Congress on Biomedical Engineering CLAIB 2014, Paraná, Argentina 29, 30 & 31 October 2014 2007, 1119 -1122.
AMA StyleG. Y. Jeong, Kee-Ho Yu. Automatic Detection of ST and T episodes using Polynomial Approximation. VI Latin American Congress on Biomedical Engineering CLAIB 2014, Paraná, Argentina 29, 30 & 31 October 2014. 2007; ():1119-1122.
Chicago/Turabian StyleG. Y. Jeong; Kee-Ho Yu. 2007. "Automatic Detection of ST and T episodes using Polynomial Approximation." VI Latin American Congress on Biomedical Engineering CLAIB 2014, Paraná, Argentina 29, 30 & 31 October 2014 , no. : 1119-1122.
For the psychophysical experiment of vibrotactile pattern recognition, experimental system consists of vibrator, vibrotactile pattern, measurement and control system is designed and prepared. The psychophysical experiment of vibrotactile pattern recognition at fingertip is carried out by the estimation of the subject group. Through the experiment, appropriate frequency bandwidth, displacement of vibrating stimuli and effect of spacing of vibrated pins for recognition of vibrotactile pattern in the human finger are discussed and derived to apply to an effective vibrotactile stimulator to be developed for tactile display.
Myoung-Jong Yoon; Kee-Ho Yu. Psychophysical Experiment of Vibrotactile Pattern Recognition at Fingertip. 2006 SICE-ICASE International Joint Conference 2006, 4601 -4605.
AMA StyleMyoung-Jong Yoon, Kee-Ho Yu. Psychophysical Experiment of Vibrotactile Pattern Recognition at Fingertip. 2006 SICE-ICASE International Joint Conference. 2006; ():4601-4605.
Chicago/Turabian StyleMyoung-Jong Yoon; Kee-Ho Yu. 2006. "Psychophysical Experiment of Vibrotactile Pattern Recognition at Fingertip." 2006 SICE-ICASE International Joint Conference , no. : 4601-4605.
In this paper, we describe the hardware configuration for the ambulatory ECG monitoring device and the algorithm for detection of ST pattern change. The ambulatory ECG recording are available for diagnosis of the heart diseases such as myocardial infarction, arrhythmia, etc. It especially is important to detect the transient ECG pattern change caused by the unbalance between the oxygen supply and the oxygen demand in the cardiac muscle that is called myocardial ischemia. This is one of the reasons why the ambulatory ECG monitoring system is necessary. We designed the portable ECG measurement device with the analysis algorithm. The algorithm analyzes the ECG signal and detects the transient ST changes. The detection of QRS complex is accomplished using its the morphological characteristics such as the steep slope and high amplitude. The developed algorithm detects the ST level change, and then classify the ST shape type using the polynomial approximation. The algorithm finds the least squares curve for the data between S wave and T wave in ECG. This curve is used for the classification of the ST shapes. ST type is classified by calculating the difference between the reference ST type and the least square curve. Through the result from the developed algorithm, we can know when the ST level change occurs and what the ST shape type is. The portable ECG device consists of instrumentation amplifier, multiplexer, micro-controller, filter and transmitter module. The designed ECG device measures ECG with four electrodes on the body and transmits the measured ECG signal to the receiver connected in PC by digital radio way. The available range of wireless communication is 70 m in building and 300 m in open ground
Gu-Young Jeong; Kee-Ho Yu. Design of Ambulatory ECG Monitoring System to detect ST pattern change. 2006 SICE-ICASE International Joint Conference 2006, 5873 -5877.
AMA StyleGu-Young Jeong, Kee-Ho Yu. Design of Ambulatory ECG Monitoring System to detect ST pattern change. 2006 SICE-ICASE International Joint Conference. 2006; ():5873-5877.
Chicago/Turabian StyleGu-Young Jeong; Kee-Ho Yu. 2006. "Design of Ambulatory ECG Monitoring System to detect ST pattern change." 2006 SICE-ICASE International Joint Conference , no. : 5873-5877.
The experiment of the shape recognition for a tactile display is carried out and analysed in this paper. The purpose of this research is the development of a tactile stimulator array to represent the obstacle information for the visually impaired to walk safely. As a first step of this research, we investigate the characteristics of tactile stimuli and design the experimental system for the physiological characteristic test based on the investigated results. In order to determine the appropriate and optimal range of the actuating frequency and displacement for the tactile stimulation array, the psychophysical experiment for the threshold of perception and recognition ability of multi-stimulation with some shapes are carried out by the estimation of the subject group. As a result the appropriate tactile stimulus intensity and frequency of the tactile stimulation array to recognize arbitrary line shapes effectively are discussed and derived.
Myoung-Jong Yoon; Kee-Ho Yu; Tae-Kyu Kwon; Nam-Gyun Kim. STUDY ON TACTILE PERCEPTION OF SHAPE FOR EFFECTIVE TACTILE DISPLAY. IFAC Proceedings Volumes 2005, 38, 260 -265.
AMA StyleMyoung-Jong Yoon, Kee-Ho Yu, Tae-Kyu Kwon, Nam-Gyun Kim. STUDY ON TACTILE PERCEPTION OF SHAPE FOR EFFECTIVE TACTILE DISPLAY. IFAC Proceedings Volumes. 2005; 38 (1):260-265.
Chicago/Turabian StyleMyoung-Jong Yoon; Kee-Ho Yu; Tae-Kyu Kwon; Nam-Gyun Kim. 2005. "STUDY ON TACTILE PERCEPTION OF SHAPE FOR EFFECTIVE TACTILE DISPLAY." IFAC Proceedings Volumes 38, no. 1: 260-265.
Kee-Ho Yu; Myoung-Jong Yoon; Tae-Kyu Kwon; Seong-Cheol Lee. Distributed flexible tactile sensor system. International Journal of Applied Electromagnetics and Mechanics 2003, 18, 53 -65.
AMA StyleKee-Ho Yu, Myoung-Jong Yoon, Tae-Kyu Kwon, Seong-Cheol Lee. Distributed flexible tactile sensor system. International Journal of Applied Electromagnetics and Mechanics. 2003; 18 (1-3):53-65.
Chicago/Turabian StyleKee-Ho Yu; Myoung-Jong Yoon; Tae-Kyu Kwon; Seong-Cheol Lee. 2003. "Distributed flexible tactile sensor system." International Journal of Applied Electromagnetics and Mechanics 18, no. 1-3: 53-65.
The prototype of the tactile sensor which has 8 × 8 array using piezoelectric film was fabricated. In the fabrication procedure, the electrode patterns and the common electrode of the thin conductive tape are attached to the both sides of the 28 üm thickness piezoelectric film using conductive adhesive. The sensor is covered with polyester film for insulation and attached to the rubber base for a stable structure. The proposed fabrication method is simple and easy to make the sensor. The sensor has the advantages in the implementing for practical applications because its structure is flexible and the shape of the each tactile element can be designed arbitrarily. The signals of a contact force to the tactile sensor are sensed and processed in the DSP system in which the signals are digitalized and filtered. Finally, the signals are integrated for taking the force profile. The processed signals of the output of the sensor are visualized in a personal computer, the shape and force distribution of the contact object are obtained. The reasonable performance for the detection of the contact state was verified through the sensing examples.
Kee-Ho Yu; Tae-Gyu Kwon; Myung-Jong Yun; Seong-Cheol Lee. DISTRIBUTED FLEXIBLE TACTILE SENSOR USING PIEZOELECTRIC FILM. IFAC Proceedings Volumes 2002, 35, 521 -526.
AMA StyleKee-Ho Yu, Tae-Gyu Kwon, Myung-Jong Yun, Seong-Cheol Lee. DISTRIBUTED FLEXIBLE TACTILE SENSOR USING PIEZOELECTRIC FILM. IFAC Proceedings Volumes. 2002; 35 (1):521-526.
Chicago/Turabian StyleKee-Ho Yu; Tae-Gyu Kwon; Myung-Jong Yun; Seong-Cheol Lee. 2002. "DISTRIBUTED FLEXIBLE TACTILE SENSOR USING PIEZOELECTRIC FILM." IFAC Proceedings Volumes 35, no. 1: 521-526.