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Sanghoon Shin,Younghun Yu 한국광학회 2009 Current Optics and Photonics Vol.13 No.2
Digital holographic microscopy allows optical path difference measurement. Optical path difference depends on the both refractive index and morphology of sample. We developed a dual-wavelength in-line digital holographic microscope that can measure simultaneously the refractive index and morphology of a sample, providing highly precise three-dimensional information. Here we propose theoretical and experimental methods for dual-wavelength in-line digital holographic microscopy. The measured data were reasonable, although there was data error. By improving the experimental method, we could measure the refractive index more precisely and obtain more accurate three- dimensional information on samples.
Sanghoon Shin,유영훈 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.4
A method is proposed for measuring the two-dimensional distribution of the refractive index in transparent micro-optical components. The proposed method combines dual-wavelength digital holographic microscopy with liquids to record holograms at different wavelengths and to numerically reconstruct the three-dimensional phase information to obtain the sample’s distribution of the refractive index. A theoretical model is proposed for determining the two-dimensional distribution of the refractive index; an achromatic lens and plate are demonstrated experimentally. Unlike conventional scanning interferometry, the proposed method supports non-scanning measurement and direct observation, independent of the sample’s shape, of the two-dimensional distribution of refractive indices in micro-optical elements.
Hilbert 변환과 Lissajous Ellipse Fitting을 이용한 Specular 표면의 3차원 측정
신상훈(Sanghoon Shin),유영훈(Younghun Yu) 한국물리학회 2022 새물리 Vol.72 No.11
이 논문에서는 한장의 줄무늬 데이터와 Hilbert 변환된 줄무늬 데이터로부터 데이터 전처리 없이 측정 대상체의 3차원 위상 데이터를 얻어내는 방법을 연구하였다. 줄무늬 투영 3차원(3-Dimensional) 측정 기법은 물체의 3차원 형상을 측정하는 효과적인 기법이고, 변형된 줄무늬로부터 위상을 추출하는 것은 3차원 측정에서 중요한 과정이다. 한장의 줄무늬 데이터를 이용하여 위상 데이터를 얻기 위해서는 백그라운드 잡음 제거와 모듈레이션 규격화를 위한 전처리가 필요하다. 본 연구에서는 줄무늬 데이터와 이를 Hilbert 변환한 데이터를 이용하여 Lissajous 도형을 구성하고, 이를 타원방정식 피팅 방법을 이용하여 전처리 없이 Lissajous 도형으로부터 줄무늬 문양의 변형된 위상을 얻는 방법을 전산기 시늉과 투과형 편향법 실험을 통해 연구하였다. This work presents a method for obtaining phase data from fringe image data and investigated Hilbert-transformed data without data preprocessing. The fringe projection technique is an effective method for measuring the three-dimensional shape of an object, and phase extraction from the deformed fringe is an important process in three-dimensional measurement. Preprocessing for background noise removal and modulation normalization is required to obtain phase data by using a single fringe image data. In this study, a Lissajous figure was constructed from fringe and Hilbert-transformed data, and the method for obtaining the deformed phase of the stripe pattern without preprocessing using the elliptic equation fitting method was studied through computer simulation and transmission-type deflection experiments.
금호강 유역의 주요 지류 수질평가에 관한 종합수질지표의 적용성 검토
신석호(Shin Sukho),임태효(Im Taehyo),김상훈(Kim Sanghoon),신동석(Shin Dougsuk),권헌각(Kwon Heongak) 한국방재학회 2018 한국방재학회논문집 Vol.18 No.2
본 연구에서는 금호강 유역의 주요 지류에 관한 최근 2년간(2015~2016년) 월별 수질 모니터링 자료를 활용하여 2006년 국립환경과학원에 의해 개발된 5개 수질항목(pH, DO, BOD, SS, T-Coli)로 구성된 한국형 종합수질지표(K-CWQI)를 산정하고 수질평가에 관한 적용성을 검토하였다. 종합수질지표 산정결과, 5개 지류 모두에서 70~90점 사이의 범위를 나타내어 수질이 비교적 양호한 것으로 평가되었다. 지류별로 살펴보면 팔거천이 88점으로 가장 놓은 점수를 보인 반면, 남천은 77점으로 가장 낮게 나타났다. 또한 종합수질지표의 적용성 검토를 위해 K-CWQI 등급과 BOD 등급의 일치정도를 비교한 결과 완전일치 및 1등급 차이가 전체의 93%에 해당하였고, K-CWQI 등급이 BOD 등급에 비해 월별 변화정도가 상대적으로 낮게 나타났다. 따라서 K-CWQI는 현재의 단일항목 수질환경기준을 반영하면서 보완해 주는 기능이 있을 뿐만 아니라 지류의 수질환경을 종합적으로 평가할 수 있음이 검토되었다. In this study, K-CWQI (Korean-Comprehensive Water Quality Index) including five items such as pH, DO, BOD, SS and T-Coli developed by NIER (National Institute of Environmental Research) in 2006 is calculated by using the result of monitoring in the major tributaries of Gumho-River Basin from 2015 to 2016 and reviewed about applicability when evaluating water quality in the basin. The scope of calculated K-CWQI is from 70 to 90 points in five tributaries and water quality of major tributaries of Gumho-River Basin is evaluated above “slightly good grade”. The highest value of K-CWQI is 88 points of Palgeacheon on the other hand, the lowest value of K-CWQI is 77 points of Namcheon. Also, the grade evaluated by K-CWQI and BOD is compared in order to apply K-CWQI to assessment of water quality. The results of this comparison are summarized as follows. The degree of agreement between the grade evaluated by K-CWQI and BOD is reached to 93% when including 1st grade difference as well as exact match and the monthly variation of K-CWQI is relatively lower than BOD. Therefore, K-CWQI not only can complement current water quality standard consisting of a single item, but also assess water environment of tributary comprehensively.