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5. To realize a variety of structural color adjustments via lossy-dielectric-based Fabry–Perot cavity structure

Author

Rahman Md Abdur, Kim Dong Kyu, Lee Jong-Kwon, and Byun Ji Young

Subjects
fabry–perot cavity, lossy dielectric, reflection colors, strong light absorption, structural colors, Physics, QC1-999
Abstract

Structural colors with tunable properties have extensive applications in surface decoration, arts, absorbers, and optical filters. Planar structures have more advantages over other forms studied to date due to their easy manufacturability. Metal-insulator-metal-based structures are one of the known methods to fabricate structural colors where colors can be tuned mainly by the thickness of the intermediate lossless insulator layer. However, generating colors by MIM structure requires a thin metallic layer on top, and the top metals’ abrasiveness and/or oxidation may degrade the colors quickly. Thus, we propose a lossy dielectric layer to replace the top metallic layer as a solution to ensure the structure’s durability by preventing scratches and oxidation. Herein, CrON/Si3N4/Metal structures have been studied where theoretical investigations suggest that highly saturated colors can be generated in the lossy-lossless dielectric structures. Experimental data validated such simulations by revealing a range of vivid colors. Furthermore, these structures can easily achieve strong light absorption (SLA) even for a thick top layer of ∼100 nm. The colors realized by these structures are appeared due to a combination of the interference effect of the asymmetric Fabry–Perot cavity structure and the absorption rate in the CrOxN1−x layer.

Published
2022
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6. Trapped charge driven degradation of perovskite solar cells

Author

Ahn, Namyoung, Kwak, Kwisung, Jang, Min Seok, Yoon, Heetae, Lee, Byung Yang, Lee, Jong-Kwon, Pikhitsa, Peter V., Byun, Junseop, and Choi, Mansoo

Subjects
Condensed Matter - Materials Science
Abstract

Perovskite solar cells have shown fast deterioration during actual operation even with encapsulation, but its mechanism has been elusive. We found the fundamental mechanism for irreversible degradation of perovskite materials in which trapped charges regardless of the polarity play a decisive role. A novel experimental setup utilizing different polarity ions revealed that the moisture induced irreversible dissociation of perovskite materials is triggered by charges trapped along grain boundaries. Our finding clearly explained the intriguing observations why light soaking induces irreversible degradation while in the dark, moisture only causes reversible hydration, and why degradation begins from different side of interface for different charge extraction layers. The deprotonation of organic cations by trapped charge induced local electric field is attributed to the initiation of irreversible decomposition.

Published
2016
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17. Quarter-Annulus Si-Photodetector with Equal Inner and Outer Radii of Curvature for Reflective Photoplethysmography Sensors.

Author

Na, Yeeun, Kim, Chaehwan, Kim, Keunhoi, Kim, Tae Hyun, Kwon, Soo Hyun, Kang, Il-Suk, Jung, Young Woo, Kim, Tae Won, Cho, Deok-Ho, An, Jihwan, Lee, Jong-Kwon, and Park, Jongcheol

Subjects
PHOTOPLETHYSMOGRAPHY, QUANTUM efficiency, CURVATURE, BIOLOGICAL monitoring, HEART beat, PHOTODETECTORS
Abstract

Reflection-type photoplethysmography (PPG) pulse sensors used in wearable smart watches, true wireless stereo, etc., have been recently considered a key component for monitoring biological signals such as heart rate, SPO3, and blood pressure. Typically, the optical front end (OFE) of these PPG sensors is heterogeneously configured and packaged with light sources and receiver chips. In this paper, a novel quarter-annulus photodetector (NQAPD) with identical inner and outer radii of curvature has been developed using a plasma dicing process to realize a ring-type OFE receiver, which maximizes manufacturing efficiency and increases the detector collection area by 36.7% compared to the rectangular PD. The fabricated NQAPD exhibits a high quantum efficiency of over 90% in the wavelength of 500 nm to 740 nm and the highest quantum efficiency of 95% with a responsivity of 0.41 A/W at the wavelength of 530 nm. Also, the NQAPD is shown to increase the SNR of the PPG signal by 5 to 7.6 dB compared to the eight rectangular PDs. Thus, reflective PPG sensors constructed with NQAPD can be applied to various wearable devices requiring low power consumption, high performance, and cost-effectiveness. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Reducing Microbial Contamination in Hematopoietic Stem Cell Products and Quality Improvement Strategy: Retrospective Analysis of 1996-2021 Data

Author

Ko, You Keun, primary, Lee, Jong Kwon, additional, Park, Hye Kyung, additional, Han, Ae Kyung, additional, Mun, Sun Kyoung, additional, Park, Hye Jeong, additional, Choung, Hae Kyoung, additional, Kim, Se Mi, additional, Choi, Kwang Mo, additional, Lee, Nam Yong, additional, Cho, Duck, additional, Kim, Dae Won, additional, and Kang, Eun-Suk, additional

Published
2023
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26. Experience of reassessing FBN1variants of uncertain significance by gene-specific guidelines

Author

Yoon, Eungjun, Lee, Jong Kwon, Park, Taek Kyu, Chang, Sung-A, Huh, June, Kim, Jong-Won, Kim, Duk-Kyung, and Jang, Ja-Hyun

Abstract

BackgroundDespite the 2015 American College of Medical Genetics and Genomics (ACMG) and Association of Molecular Pathology (AMP) guideline, many variants of FBN1gene remain inconclusive. In line with publication of the FBN1-specific variant interpretation guideline by ClinGen in 2022, we reassessed variants of uncertain significance (VUS) in FBN1gene found in our institution.MethodsVUS found in the course of FBN1sequencing between December 2015 and April 2022 were reassessed based on FBN1-specific variant interpretation guideline, review of updated literatures and additional genetic tests including family study and/or RNA study if available.ResultsOut of 695 patients who underwent FBN1sequencing, 61 VUS were found in 69 patients. Among them, 38 VUS in 43 patients (62.3%) were reclassified as pathogenic and likely pathogenic variant ((L)PV), including 20 novel (L)PV. Major causes of reclassification were: (1) gene-specific modification of ACMG/AMP criteria, (2) updated literatures and (3) additional genetic tests. The most important evidence for reclassification was clarification of critical amino acid residues.ConclusionsAfter reassessing FBN1variants according to FBN1-specific guideline and up-to-date database, a significant number of VUS was reclassified. Clinical laboratories are encouraged to perform variant reassessment at regular intervals or when there is a major change in the principle of variant interpretation.

Published
2024
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31. Volume-grating Stokesmeter based on photonic bandgap structures

Author

Lee, Jong-Kwon, Liu, Xue, and Shahriar, M.S.

Subjects
Optical communications -- Research, Parametric devices -- Properties, Astronomy, Physics
Abstract

An inherent polarization sensitivity of a volume grating, in general, can be used to determine all the Stokes parameters of input beams. We demonstrate the polarization-dependent bandgap in a photonic crystal in principle at any wavelength using the finite-difference time-domain method. We show how this bandgap can be used to realize a volume-grating Stokesmeter. We also present an explicit design for a high-speed version of such a Stokesmeter and identify design constraints that arise in this context. Finally, we describe a spectrally resolved volume-grating Stokesmeter based on the tunability of a photonic bandgap material. OCIS codes: 050.7330, 110.5405, 230.0230.

Published
2009

47. Effect of zinc oxide nanoparticles on dams and embryo–fetal development in rats

Author

Hong, Jeong-Sup, Park, Myeong-Kyu, Kim, Min-Seok, Lim, Jeong-Hyeon, Park, Gil-Jong, Maeng, Eun-Ho, Shin, Jae-Ho, Kim, Yu-Ri, Kim, Meyoung-Kon, Lee, Jong-Kwon, Park, Jin-A, Kim, Jong-Choon, and Shin, Ho-Chul

Subjects
zinc oxide, Metal Nanoparticles, maternal toxicity, Rats, Fetal Development, Rats, Sprague-Dawley, Pregnancy, Toxicity Tests, developmental toxicity, Animals, nanoparticles, Female, nanotoxicology, teratogenicity, reproductive and urinary physiology, Original Research
Abstract

This study investigated the potential adverse effects of zinc oxide nanoparticles (ZnO(SM20[-]) NPs; negatively charged, 20 nm) on pregnant dams and embryo-fetal development after maternal exposure over the period of gestational days 5-19 with Sprague Dawley rats. ZnO(SM20(-)) NPs were administered to pregnant rats by gavage at 0 mg/kg/day, 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day. All dams were subjected to caesarean section on gestational day 20, and all the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight at 400 mg/kg/day and decreased liver weight, and increased adrenal glands weight at 200 mg/kg/day and 400 mg/kg/day. However, no treatment-related difference in the number of corpora lutea, the number of implantation sites, the implantation rate (%), resorption, dead fetuses, litter size, fetal deaths, fetal and placental weights, and sex ratio were observed between the groups. Morphological examinations of the fetuses demonstrated no significant difference in the incidences of abnormalities between the groups. No significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that a 15-day repeated oral dose of ZnO(SM20(-)) was minimally maternotoxic at dose of 200 mg/kg/day and 400 mg/kg/day.

Published
2014

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