Enhanced fluorescence from CdSe/ZnS quantum dot nanophosphors embedded in a one-dimensional photonic crystal backbone structure.

Min, Kyungtaek,Choi, Serok,Choi, Yunkyoung,Jeon, Heonsu RSC Pub 2014 Nanoscale Vol.6 No.23

<P>A nano-engineered phosphor structure that produces enhanced fluorescence is reported. Two kinds of polymer materials with different refractive indices are spin-coated alternately to realize a one-dimensional (1D) photonic crystal (PC) phosphor platform, in which CdSe/ZnS core-shell quantum dots (QDs) were embedded as a fluorescence agent. The 1D PC phosphor structure is designed to match the pump photon energy with one of the photonic band-edges (PBEs), where the photon group velocity becomes zero, and thus the interaction between pump photons and fluorescent centres strengthened. A reference phosphor structure is also designed and fabricated; however, it has no PBE and exhibited bulk-like photonic properties. The fluorescence intensity from the 1D PC phosphors is examined during the pump photon energy scanning across the PBE. It is found that fluorescence from the 1D PC phosphor reaches its maximum when the pump photon energy coincides with the PBE, which is consistent with the theoretical prediction. In comparison with the reference phosphor, the fluorescence from the 1D PC phosphor is measured to be enhanced by a factor of 1.36.</P>

Aliveness detection of fingerprints with Image Quality Analysis

Heeseung Choi,Kyungtaek Choi,Jaihie Kim 대한전자공학회 2008 ICEIC:International Conference on Electronics, Inf Vol.1 No.1

Fake finger submission to the sensor is a major problem in fingerprint recognition systems. In this paper, we introduce a novel aliveness detection method with image quality analysis. For convenience and usefulness of field application, multiple static features are considered to detect ‘live’ and ‘fake’ fingerprint images. Power spectrum, directional contrast and ridge thickness of image are analyzed. Our static features can reflect the physiological and statistical characteristics of live and fake fingerprint. Aliveness score of each feature is calculated and fused in feature level through polynomial SVM (Support Vector Machine) classifier. In our data set, proposed method has approximately 0.49% EER (Equal Error Rate) at best only using a single image. Our approach will provide a faster and useful technique for aliveness check for field applications.

비접촉식 5 지문 영상 획득 센서 개발

최희승(Heeseung Choi),최경택(Kyungtaek Choi),김재희(Jaihie Kim) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.11

This paper introduce a new touchless fingerprint sensor. A single camera and a rotation mirror are used to capture all 5 fingerprint images which cannot be detectable using conventional fingerprint sensors. We also propose the techniques which can solve the image contrast, nonuniform illumination, DOF (Depth of Field) problems. This new sensor leads to bringing new challenges in the field of fingerprint recognition.

거울을 이용한 비접촉식 지문 센서 개발

최희승(Heeseung Choi),최경택(Kyungtaek Choi),김재희(Jaihie Kim) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7

This paper introduce a new touchless fingerprint sensor. Two mirrors are used to capture the side fingerprint images which cannot detectable using a single camera. We also propose the techniques which can solve the image contrast, nonuniform illumination, DOF(Depth of Field) problems. This new sensor leads to bringing new challenges in the field of fingerprint recognition.

Model calculations for enhanced fluorescence in photonic crystal phosphor.

Min, Kyungtaek,Choi, Yun-Kyoung,Jeon, Heonsu Optical Society of America 2012 Optics express Vol.20 No.3

<P>We propose a novel photonic structure, based on the photonic crystal (PC) effect, which simulations show results in an improved fluorescence efficiency from embedded phosphor. To be specific, the phosphor pumping efficiency can be significantly improved by tuning the pump photon energy to a photonic band-edge (PBE) of the PC phosphor. We have confirmed this theoretically by calculating optical properties of one-dimensional PC phosphor structures using the transfer-matrix method and plane-wave expansion method. For a particular model structure based on a quantum dot phosphor, the fluorescence enhancement factor was estimated to be as high as 6.9 for a monochromatic pump source and 2.2 for a broad bandwidth (20 nm) pump source.</P>

연료전지 분야의 미래 유망기술 탐색

김경택(Kyungtaek Kim),유란(Ran Yoo),최지영(Jeeyoung Choi),안지석(Jiseok Ahn),백운호(Woonho Baek),이성곤(Seongkon Lee) 한국에너지기후변화학회 2021 한국에너지기후변화학회 학술대회 Vol.2021 No.5

P-47 Elucidation of Genetic Susceptibility of Patients with Nontuberculous Mycobacterial Lung Disease Using Genome-Wide Association Study

조재영,( Kyungtaek Park ),( Seung Ho Choi ),( Sun Mi Choi ),( Jinwoo Lee ),( Chang-hoon Lee ),( Jung-kyu Lee ),( Eun Young Heo ),( Deog Kyeom Kim ),( Yeon Joo Lee ),( Jong Sun Park ),( Young-jae Cho ),( 대한결핵 및 호흡기학회 2017 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.124 No.0

Background: The clinical features of patients with nontuberculous mycobacteria (NTM) lung disease are well described, however, genetic factors of susceptibility to NTM lung disease are not understood. To examine genetic variants in patients with NTM lung disease, we conducted a genome-wide association study (GWAS). Methods: We genotyped 408 patients with NTM lung disease using the Illumina HumanCore BeadChip, and performed an association study with existing genotyping data of 4080 healthy controls from three Korean cohorts (Korean Association REsource [KARE], Healthy Twin Study, and routine health check-up program at the Seoul National University Hospital). Results: We identified three single nucleotide polymorphisms (SNPs) located in chromosome 14q31.1. The strongest signal was obtained at the rs1797671 (P = 5.76ⅹ10-8, OR = 2.11, 95% CI =95% CI = 1.61 to 2.76) in the intron of CEP128. rs10133034 in the intron of CEP128 and intergenic rs2150330 were also associated with NTM lung disease (P = 3.88ⅹ10-7 , OR = 1.99, 95% CI = 1.52 to 2.59 and P = 1.65ⅹ10-7, OR = 2.47, 95% CI = 1.76 to 3.47, respectively). Our estimate of the proportion of variance in the phenotype explained by all GWAS SNPs was 0.30 ± 0.06. Conclusions: We identified new genetic variants associated with NTM lung disease. The replication study to validate the result is going on. These findings may provide insight into the pathogenesis of NTM lung disease and identifying susceptible individuals to this disease.

우리나라 산림경영인의 산림경영 현황과 인식

민경택 ( Kyungtaek Min ),최준영 ( Junyeong Choi ) 한국산림경제학회 2018 산림경제연구 Vol.25 No.1

이 연구는 산림경영인의 산림경영 현황과 산림경영에 대한 인식을 조사하기 위해 수행되었다. 10ha이상의 산림을 소유하고 산림경영에 적극적인 산림경영인 300명을 대상으로 설문조사를 실시하였다. 대부분의 산림경영인은 단기임산물 위주의 수익형태를 가진다. 산림작물 재배의 비율이 88.4%에 이르며, 가구소득에서도 단기임산물의 비중이 87.5%를 차지한다. 즉, 산림경영의 목적이 목재 생산보다 산림작물 재배에 있는 것으로 판단된다. 입목 가격은 산림경영인의 기대보다 낮은 것으로 나타났다. 소나무의 경우 시세는 336.8만 원/㏊이지만 산림경영인의 기대 가격 547.0만 원/㏊에 크게 못 미친다. 산림경영의 수익성 증대를 위한 정책 선호도에서 ‘산림규제 완화'(66.7%)의 응답이 가장 높았다. 또, 산림경영인 은퇴 이후 경영을 계승하기 위해 ‘산림직불제 도입'(69.0%)이 필요하다는 응답이 많았다. The objective of this study is to survey the forest management status and the perception of forest owners, who own more than 10 hectares of forestland and manage their forest as household income source. 300 forest owners are selected as subject, and surveyed face-to-face. Most forest management focuses on short-term non-timber forest products. The proportion of forest farming reaches 88.4 percent, accounting for 87.5 percent of their income. Thus, the purpose of forest management is to do forest farming rather than wood production. Moreover, stumpage prices are lower than their expectation. For pine trees, the current stumpage price is 3,368 thousand won per hectare, but the expected price is 5,476 thousand won per hectare. In terms of policy to enhance profitability of forest management, “easing forest regulations”(66.7 percent) is preferred the most. To succeed forest management after present owner’s retirement, income support system is said to be needed urgently.

생태경관보전지역인 삼육대 불암산 조류 종 관찰을 통한 제명호의 생태적 가치 연구

임경택(Kyungtaek Lim),신채율(Chaeyul Shin),최리아(Lia Choi),한다현(Dahyun Han),정훈 반려동물연구학회 2022 Animalia Vol.4 No.1

본 연구는 생태·경관보전 지역인 삼육대 불암산의 조류 종 관찰을 통해 2017년 관찰 결과와 비교하여 제명호의 생태적 가치에 대해 연구하였다. 6월 25일부터 9월 26일까지 총 20번의 현장조사를 진행하였고, 제명호~삼육대 후문 까지를 세부 조사 지역으로 정하였다. 조사지역에서 하루 2시간 이내로 쌍안경과 카메라를 이용하여 직접 관찰, 또는 소리를 이용해 동정 후 기록하였다. 그 결과 2017년의 제명호 인근 조류 종 관찰 자료는 약 35 종이 관찰되었으나 이번에는 29종으로 감소하였으며, 관찰된 보호종 또한 10종에서 8종으로 감소하였다. 감소의 원인으로는 늘어난 강수량과 물이 충분히 고이지 않는 웅덩이로 꼽고 있으며 본 연구결과는 생태·경관보전 지역인 불암산 제명호 부근의 조류 서식지 훼손 및 훼손 가능성을 판별하여 서식지의 보강 및 앞으로의 관리에 대한 개선방안을 고찰하는데 중요한 자료가 될 것으로 예상된다. This study was aimed to examine and study the ecological values of Jemyung Lake compared to the observation results in 2017 through the observation of bird species of Buram Mountain in Sahmyook University, an Ecological Landscape Conservation Area(ELCA). For achieving the aim of this study, a total of 20 field investigations were conducted from June 25,2022 to September 26, 2022, and the area from Jemyung Lake to the back gate of Sahmyook University was set up for a detailed investigation area. Within 2 hours a day in the detailed investigation area, we directly recorded observation with binoculars and camera or sorted by the sound of bird species. The results of the analysis are that about 35 bird species investigation data near Jemyung Lake were observed in 2017, but this time, the number of bird species decreased to 29, and the observed legal protected species also decreased from 10 to 8. The reason for the decrease is that increased precipitation and puddles that does not form enough water. The implication of the study is to be an important data for improvement plan consideration about habitats reinforcement and care for future through discrimination of bird habitats damage and the possibility of damage near Jemyung Lake in Buram Mountain, an Ecological Landscape Conservation Area(ELCA)

무인 식물성장 시스템을 위한 이동식 인공지능 화분 및 통합 어플리케이션

최원구(WonGu Choi),장성욱(SungWook Jang),홍경택(KyungTaek Hong) 한국정보과학회 2014 한국정보과학회 학술발표논문집 Vol.2014 No.6