Development of Digital Holographic Microscopy on an All-Optical Phase Shifter

최은서,마혜준,이승석,박소희 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.9

We propose an all-optical phase-shifting method using Yb-doped optical bers and demonstrate its potential in on-axis digital holography microscopy (DHM) system. The Yb-doped optical ber induces a phase change under optical pumping conditions. The induced phase shift shows a good linear response to applied pumping currents, and N-step phase-shifting up to 2 can be properly performed. Four-, six-, and eight-step phase-shifting methods are performed, and the phase re- trievals from their phase-shifted interferograms are achieved using an interframe correlation matrix method. An 8-step phase shifting-based reconstruction, which is effective for background noise re- duction, is used for 3D imaging of an indium tin oxide (ITO) thin lm and an organic light-emitting diode (OLED) thin lm. The reconstructed surface prole was in agreement with the step structure of the samples. The proposed all-optical phase-shifting method is expected to be applied to various optical imaging systems using ber-based phase-shifting interferometers.

Short duration of pain onset is related to increased risk of ERCP-related adverse events

최은서,이시영,장성일,박상호,도민영,이동기,조재희 대한내과학회 2023 대한내과학회 추계학술대회 Vol.2023 No.2

Evaluation of the Enhanced Antioxidant Activity of Curcumin within Exosomes by Fluorescence Monitoring

최은서,강윤영,목혜정 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.2

In this study, we compared the antioxidant activities of curcumin (Cur) and a Cur formulation using a fluorescence analysis assay. The Cur formulation was prepared by a simple incorporation of Cur into exosomes (EXO) to produce Cur/EXOs. Free Cur had a low fluorescence intensity in aqueous solution because of its poor stability as a result of its autoxidation, whereas a significantly higher fluorescence intensity was observed for Cur/EXOs. Compared to free Cur, the increased level of intact Cur in EXOs allowed for enhanced antioxidant activity in H2O2 scavenging activity and DPPH assays. Compared to Cur at high concentration (200 μM), Cur/ EXOs were significantly less cytotoxic. The antioxidant activity of Cur or Cur/EXOs in cells could be easily demonstrated by monitoring decreases in their fluorescence intensity. Following subcutaneous injection, the fluorescence intensities of Cur/EXOs were much higher than that of Cur, suggesting that Cur/EXOs improve Cur stability in vivo. Taken together, we have demonstrated the superiority of Cur/EXOs over free Cur in terms of aqueous stability and antioxidant activity using fluorescence monitoring both in vitro and in vivo.

광섬유 기반의 광단층이미징 (OCT)의 원리 및 응용

최은서,신용진,김영섭,이병하 한국물리학회 2007 새물리 Vol.54 No.5

본 논문에서는 여러 의학영상기법 중에서 광학적 기법을 이용하는 광단층이미징에 대해서 소개하고자 한다. 광단층이미징은 백색광 간섭계와 근적외선 광을 이용하여 시료의 내부구조에 의해 발생한 간섭무늬를 측정함으로써 비절개적으로 생체단층영상을 구현한다. 구현된 영상은 수 마이크론에 이르는 고분해능이 가능하며 실시간 영상을 제공할 수 있다는 장점을 가지고 있다. 이러한 광단층이미징 시스템은 최근 광섬유를 기반으로 구성되고 있으며 향상된 이미징 기능을 수행하기 위해서 광섬유 기반의 여러 기술들을 차용하여 활용하고 있다. 광섬유 기반의 광단층이미징 기법의 원리를 소개하고 보다 향상된 이미징 성능을 위해 사용되는 광섬유 기반의 여러 연구 동향을 소개하고자 한다. 광단층이미징의 주된 연구분야로써 크게 세가지의 주제를 정리하였는데 먼저 특수광섬유 기반의 초광대역광원의 발생방법과 이를 이용하여 초고분해능 광단층이미징을 구현 방법을 소개하고 둘째로는 실시간 고감도 이미징을 위한 파장 가변형 광섬유 레이저를 이용한 스펙트럼 측정을 소개한다. 마지막으로 임상에서 실제적인 조기진단용 이미징을 위해 내시경 형태로 제작된 광섬유 기반의 광단층이미징 프로브에 관한 연구 동향에 대해서 정리하였다. 고분해능 정적 광섬유 간섭계를 기반으로 하는 내시경 광단층이미징 시스템은 질병의 조기 진단에 있어서 높은 가능성을 가진 미래의 대안으로 예상되는 바이다. We have introduced optical coherence tomography (OCT) as a promising medical imaging modality. OCT, which is based on a white-light interferometer with a near-infrared light source, can perform non-invasive optical cross-sectional imaging by measuring the interference fringes resulting from the internal structure of a sample. OCT also yields an anatomic view with a high-resolution of a few microns, providing $in-vivo$ real-time imaging. Utilization of fiber-based technologies in the field of optical measurement has allowed a state-of-art fiber-based OCT system to be achieved. We explain the principle of the fiber-based OCT and describe the three major concerns for improving the imaging performance by exploiting fiber-based technology: The first is the supercontinuum generation with the aid of a specialty fiber to improve the resolution further up to sub-microns, and the second deals the topic of FD-OCT, which uses a wavelength-swept fiber laser to perfom high-sensitivity faster imaging. The final content is focused on the miniaturized OCT probe or endodcopic OCT for the realization of practical early diagnostics. In the clinical early detection of disease, an ultra-high-resolution FD-OCT interfaced with an endoscopic probe could be a promising candidate.

직장탈 치료에 있어서 Delorme 술식과 Altemeier 술식의 비교

최은서,김경종,김정용,민영돈 대한외과학회 2002 대한외과학회 학술대회 초록집 Vol.2002 No.5

Measurement of High Temperature by Using a Fiber Interferometer Based on a Photonic Crystal Fiber

최은서,김명진,신용진 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.6

We demonstrated the performance of a fiber sensor based on a photonic crystal fiber (PCF) for the detection of high temperatures. The proposed fiber sensor was implemented by collapsing the air holes of the PCF with an arc discharge and forming an in-fiber Mach-Zehnder interferometer. The intentionally collapsed parts in the PCF cause coupling between the core mode and the cladding modes, which produces interference fringes in the transmission spectrum. The spectral response was observed while changing the ambient temperature. The fiber sensor operated properly at high temperatures up to 1000 ℃. The proposed fiber sensor presented good reliability after repeated temperature variation cycles and showed low hysteresis over wide temperature range. We expect this compact fiber sensor to be applied to monitoring the high-temperature distribution around a thin film sensor and to be an alternative for a strain/pressure thin film sensor under high temperatures in harsh conditions.

LED 배치 조건 변화에 따른 도광판 성능 향상 기법

최은서,최영희,신용진 한국물리학회 2009 새물리 Vol.59 No.2

We demonstrated the feasibility of the simplified simulation model for the calculation of light guide panel (LGP) without laborious computational loads with providing the effect of LED's arrangement condition on the LGP performance. From the results of this simulation, the optimized condition of the position and incidence angle of LED was determined. In this simulation, we used linear or curved scatterer-plane experiencing Gaussian scattering on the surface. The distance between LED's and incidence angle of LED are varied with calculating the average brightness and the uniformity. The calculation results present that the optimal distance and incidence angle are 13 mm and 5 degree. Under the conditions, the better results was obtained in the case of curved scatterer-plane, where the wider area was covered having improved uniformity. As a result, the LGP performance was very sensitive to the LED arrangement condition. We could make use of this basic calculation result to design an optimized inner-scatterer-based LGP and to improve the LGP performance. 본 연구는 단순산란평판과 그 평판에서의 가우시안 산란효과를 이용한 도광판 성능 예측 전산모사 기법을 바탕으로 광원의 배치조건에 따른 도광판 성능의 변화를 관찰함으로써 도광판에 입사되는 광원의 최적 배치 조건을 찾고자 하였다. 이를 위해서 산란평판을 선형과 곡면 이렇게 두 가지로 마련하였고 광원의 배치조건으로 광원간의 거리와 광원의 입사각을 변화시키면서 광원 배치에 따른 도광판 효율을 평균밝기와 균일도를 통해서 비교 분석하였다. 광원간의 거리차이는 13 mm이고 입사각은 5˚인 경우 가장 좋은 성능을 가짐을 확인할 수 있었다. 이 조건하에서 곡면의 경우 보다 넓은 면적에 향상된 균일도를 가지게 됨을 알 수 있었으며 광원의 배치조건에 매우 민감하게 도광판 성능이 변화됨을 확인할 수 있었다. 이러한 결과를 바탕으로 도광판 광원을 보다 효율적으로 이용하기 위한 최적 조건을 도출하는데 유용하게 사용될 것으로 예상된다.

40세 전후 유방암환자에 있어서 임상 및 병리학적 특징

최은서,김권천,조현진,장정환,김경종 대한외과학회 2003 대한외과학회 학술대회 초록집 Vol.2003 No.5

‘통일세’ 보다 ‘지속가능한 통일교육’이 더 시급하다

최은서 민족21 2010 민족21 Vol.- No.-

조기위암의 형태학적인 분류에 따른 임파절 전이 양상

최은서,강길,박정희,장정환,김권천,김경종,민영돈 朝鮮大學校 附設 醫學硏究所 2004 The Medical Journal of Chosun University Vol.29 No.1

Currently, in the limited cases of early gastric cancer (EGC), endoscopic mucosal resection (EMR) is used for curative treatment. However, its completeness is still controversial. The purpose of this study was to review the suggested indications of EMR. We retrospectively analyzed 234 patients with EGC who underwent curative (RO) gastrectomy. The enrolled cases were further classified into mucosal and submucosal types, and mucosal EGC were further classified according to the size, gross type and histologic pattern. 133 patients had mucosal cancers and 101 patients submucosal. The overall incidence of positive lymph node was 14.1% (33/234), the incidence of mucosal cancer was 8. 3% (11/133), which was significantly lower than that of submucosal, 22% (22/101). Of 133 patients with mucosal EGC, 90 were smaller than 2㎝ in size and the incidence of lymph node metastasis was 5.6% (5/90), compared to 43 of larger than 2㎝ with the incidence of 14% (6/43). According to the gross type classification of mucosal cancer, incidence of lymph node metastasis in protruded type (EGC type Ⅰ, Ⅱa, Ⅰ+Ⅱa) was 15.4% (4/26), nat type(EGC type Ⅱb) 2. 9% (1/35), depressed type (EGC type Ⅱc, Ⅲ) 8.3% (6/72). Lymph node metastasis in differentiated type of mucosal cancer was 6.9% (5/72) and undifferentiatcd type 9.8% (6/61). In this study, there was no single indication free from lymph node metastasis, It is thought that the selection of EMR for the curative treatment of EGC should be considered carefully and more clinical studies with long-term follow up are necessary for EMR to be generally acceptable.