Kyung-Il Joo

Dr. Kyung-Il Joo


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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26 August 2019 in IEEE Transactions on Industrial Electronics
Verified
Journal Article
Open access
KJKyung-Il Joo
Kyung-Il Joo
MPMin-Kyu Park
Min-Kyu Park
HPHeewon Park
Heewon Park
TLTae-Hyun Lee
Tae-Hyun Lee
Ki-Chul KwonKi-Chul Kwon
Ki-Chul Kwon
HKHak-Rin Kim
Hak-Rin Kim
We propose a time-sequential switching light-field (LF) camera for alternative image capture of high-resolution two-dimensional (2D) images and three-dimensional (3D) LF elemental images as additional functionalities. For image data acquisitions of both the 2D and 3D LF imaging of moving objects at a video-frame rate (or even higher frame rate up to approximately 1000 fps), a polarization-dependent-switching micro-lens array (PMLA) is implemented in the LF camera system instead of a conventional passive-type MLA. By controlling the incident polarization conditions using an electrically fast-switching liquid crystal layer, the imaging mode can be time-sequentially switched quite rapidly (switching times of approximately 220 μs and 290 μs for the mode conversions from the 3D LF to the 2D mode, and the reversal mode change, respectively). Using the elemental image sets sampled from the alternating time-sequential imaging results, either directional-view images or depth-refocused images can be reconstructed and provided at a moving picture frame-rate. The depth-refocused images are possible for a wide depth range from 25 cm to 350 cm. Directional views of 22 x 22 and 9 x 9 in portions can be reconstructed for the single shot image capture and the time-sequential video-rate image capture, respectively.

24 June 2019 in IEEE Photonics Journal
Verified
Journal Article
Open access
MPMinyoung Park
Minyoung Park
KJKyung-Il Joo
Kyung-Il Joo
HKHak-Rin Kim
Hak-Rin Kim
HCHee-Jin Choi
Hee-Jin Choi
An augmented-reality (AR) device which presents virtual volumetric images to switchable integrated spaces is proposed and demonstrated. A bi-focal geometric phase (GP) lens can project the integrated volumetric images to switchable integrated spaces by switching the polarization of them. For that purpose, a combination of GP lens and an active polarization switching device (APSD) has been adopted. A demonstration of an AR display with switchable integrations is also provided to verify the proposed concept.

24 May 2020 in Crystals
Verified
Journal Article
Open access
PDF file
TLTae-Hyun Lee
Tae-Hyun Lee
KJKyung-Il Joo
Kyung-Il Joo
HKHak-Rin Kim
Hak-Rin Kim
We improved the three-dimensional (3D) crosstalk level of multi-view 3D displays using a lens array with small f-number, thereby facilitating a wide 3D viewing window. In particular, we designed a polarization-dependent-switching liquid crystal (LC)-based gradient refractive index (GRIN) lens array that could be switched between 2D and 3D viewing modes. For the GRIN lens with a small f-number (1.08), we studied the effect of the interfacial curvature between the plano-concave isotropic polymer layer and the plano-convex birefringent LC layer on the aberration properties. We examined the conventional spherical, quadratic polynomial aspherical, and a high-order (fourth-order) polynomial aspherical curvature. For the high-order polynomial aspherical curvature, the achievable transverse spherical aberration (TSA = 10.2 µm) was considerably lower than that with the spherical (TSA = 100.3 µm) and quadratic polynomial aspherical (TSA = 30.4 µm) curvatures. Consequently, the angular luminance distributions for each view were sharper for the high-order polynomial interfacial curvature. We designed multi-view (43-view) 3D displays using the arrays of switchable LC lenses with different curvatures, and the average adjacent crosstalk levels within the entire viewing window (50°) were 68.5%, 73.3%, and 60.0% for the spherical, quadratic polynomial aspherical, and high-order polynomial aspherical curvatures, respectively.

27 January 2022 in Advanced Materials Interfaces
Verified
Journal Article
Closed access
PDF file
YSYoung‐Chul Shin
Young‐Chul Shin
JPJi‐Sub Park
Ji‐Sub Park
KJKyung-Il Joo
Kyung-Il Joo
HKHyun Gyu Kim
Hyun Gyu Kim
RMRamesh Manda
Ramesh Manda
HKHak-Rin Kim
Hak-Rin Kim

5 April 2025 in Journal of the Society for Information Display
Verified
Journal Article
Open access
HJHyeon‐Su Jeong
Hyeon‐Su Jeong
MEMunkh-Uchral Erdenebat
Munkh-Uchral Erdenebat
JSJin‐Hyeok Seo
Jin‐Hyeok Seo
MKMin‐Seok Kim
Min‐Seok Kim
YCYoung‐Min Cho
Young‐Min Cho
HKHak-Rin Kim
Hak-Rin Kim
We propose an active‐switching light‐field (LF) camera system that significantly extends the measurable depth range over conventional passive‐optics‐based LF systems by integrating a stacked geometric phase lens (GPL) module in a compact design. During elemental image acquisition and LF rendering, chromatic aberration in the focus‐tunable GPL is compensated by adjusting the reconstruction depth and magnification for each color channel. Additionally, the optimal GPL operation sets are selected based on color‐dependent depth‐of‐focus conditions. These optimizations enable the proposed GPL‐based LF system to achieve full‐color, depth‐enhanced LF imaging while mitigating the typical trade‐off between spatial resolution and depth of field limitations.

1 January 2024
Verified
Conference Paper
Closed access
PDF file
TLTae-Hyun Lee
Tae-Hyun Lee
MPMin-Kyu Park
Min-Kyu Park
SLSungjin Lim
Sungjin Lim
KLKi-Dong Lim
Ki-Dong Lim
KJKyung-Il Joo
Kyung-Il Joo
We developed a light-field (LF) camera which can switch between 2D and 3D capturing mode. LF camera was developed with switchable micro-lens array (MLA) according to the polarization state of incident light.