• 한국항해항만학회지
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• 제26권2호
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• pp.235-243
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• 2002

황섬유의 최저손실 파장영역인 $1.55\mu\textrm{m}$에서 고출력으로 안정하게 농작하는 광센서용 광원인 반도체 레이저를 제작하기 위하여 이론적인 해석을 수행한 후 제작하였다. 활성영역과 SCH층의 재료는 $Ln_{1-x}Ga_xAs_yP_{1-y}$를 사용하였다. 광센서용 광원으로 사용되기 위해서는 넓은 스펙트럼 폭을 가지며, 가간섭 길이가 짧은 특성을 가지는 조건을 만족해야 한다. 따라서, 반도체 레이저에서 레이징을 억제시켜 줌으로써 넓은 스펙트럼 폭을 가지도록 설계를 하였고, 광섬유와 결합효율을 높일 수 있도록 tapered 형태의 스트라입 구조를 채택하여 마스크 패턴을 형성하였다. 또한, 레이징을 억제하기 위하여 후면에 윈도우 영역을 두었고, 측방향으로 경사각을 두어 반사도를 낮추도록 설계 및 제작하였다. 7도와 15도의 측면 경사각을 가지는 구조와 굽은 스트라입 구조를 가지는 소자를 제작하여 특성을 측정한 결과, 광센서용 광원으로서 적용이 가능한 광출력 특성과 넓은 스펙트럼 폭을 가졌다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.370-373
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• 2003

Superluminescent diodes(SLDs)는 광섬유 자이로스코프, OTDR, 중단거리 광통신시스템과 같은 광측정 시스템으로의 응용에 있어서 최적의 광원이다. SLD의 넓은 스펙트럼 특성은 Rayleigh 후방산란 잡음, 편광잡음, 광섬유 자이로 스코프에서의 비선형 Ken 효과에 의한 bias offset을 감소시킨다. 본 논문에서 레이징을 억제하기 위해서 윈도우 영역을 갖고 측방향으로 경사진 SCH(Separate Confinement Heterostructure)-SLD를 제안하였다. 제작된 소자의 출력은 펄스 구동 200mA, $25^{\circ}C$에서 11mW였다. 그리고, 120mA에서 수평 및 수직 방사각은 31$^{\circ}$$\times$38$^{\circ}$였다.

• 사물인터넷융복합논문지
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• 제5권2호
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• pp.15-20
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• 2019

기계학습 연구가 발달함에 따라 번역 분야 및, 광학 문자 인식(Optical Character Recognition, OCR) 등의 이미지 분석 기술은 뛰어난 발전을 보였다. 하지만 이 두 가지를 접목시킨 영상 번역은 기존의 개발에 비해 그 진척이 더딘 편이다. 본 논문에서는 기존의 OCR 기술과 번역기술을 접목시킨 이미지 번역기를 개발하고 그 효용성을 검증한다. 개발에 앞서 본 시스템을 구현하기 위하여 어떤 기능을 필요로 하는지, 기능을 구현하기 위한 방법은 어떤 것이 있는지 제시한 뒤 각기 그 성능을 시험하였다. 본 논문을 통하여 개발된 응용프로그램으로 사용자들은 좀 더 편리하게 번역에 접근할 수 있으며, 영상 번역이라는 특수한 환경으로 한정된 번역기능에서 벗어나 어떠한 환경에서라도 제공되는 편의성을 확보하는데 기여할 수 있을 것이다.

• E2M - 전기 전자와 첨단 소재
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• 제8권4호
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• pp.406-412
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• 1995

A n-CdS thin films were evaporated by thermal evaporation method and their structure, optical transmission spectra and electrical characteristics were investigated. The photovoltaic characteristics of solar cells which were fabricated in optimum conditions measured. The evaporated CdS thin films showed in hexagonal structure and above 80% of optical transmission spectra regardless of impurity doping. The high quality thin films could be obtained at 150.deg. C temperature of substrate, which is useful for solar cell window layer with low resistivity of 6*10$\^$-2/(.ohm.-cm) by In doping We measured the electrical and optical characteristics of the n-CdS/p-InP heterojunction solar cells. The most efficient photovoltaic characteristics of heterojunction solar cells had the open circuit voltage of 0.66V, short circuit current density of 13.85mA/cm$\^$2/, fill factor of 0.576 and conversion efficiency of 8.78% under 60mW/cm$\^$2/ illumination.

• 전자공학회논문지S
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• 제34S권1호
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• pp.132-144
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• 1997

The rotation-invariant pattern recognition filter using circular harmonic function of the wavelet transforme dsreference image by morlet, mexican-hat, and haar wavelt function is proposed. The rotated reference images, the images sililar to the reference image, and the images which are added by random noise are used for the inpt images, and in case of the input images with random noise, they are applied to the recognition after removing the random noise by the transformed moving average method with proper thresholding value and window size. The proposed optical wavelet circular harmonic matched filter (WCHMF) is a type of the matche dfilter, so that it can be applied to the 4f vander lugt optical correlation system. SNR and discrimination capability of the proposed filter are compared with those of the conventional HF, the POCHF, and the BPOCHF. The proper wavelet function for the reference image used in this paper is achieved by applying morlet, mexican-hat, and harr wavelet function ot the proposed filter, and the proposed filter has good SNR and discrimination capability with rotation-invariance in case of the morlet wavelet function.

• 대한기계학회논문집B
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• 제29권2호
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• pp.224-231
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• 2005

The present study investigates flow characteristics in an optical disc drive (ODD). Detailed knowledge of the flow characteristics is essential to analyze flow-induced noise and vibration, forced convection and flow friction loss. The ODD used in a personal computer is used for the experiment and rotating velocity of disc is under the 4500 rpm. Time-resolved velocity component and velocity spectrum are obtained using the laser Doppler anemometry (LDA), and the flow patterns induced by rotating disc in the ODD are calculated by a commercial finite volume method at the same time. The results show that the front holes reduce flow-induced noise and the position of pickup body only affects flow near the window. Furthermore, it is possible for cooling of heat sources in the drive through measuring the flow fields under the tray. In addition, the numerical results are well matched up to the experimental results, therefore, the validation of the numerical results can be achieved. From the validation of numerical results, it is possible to predict the flow characteristics of the region where it is unable to conduct the experiment.

• 한국정밀공학회지
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• 제18권5호
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• pp.90-97
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• 2001

An electronic speckle pattern interferometry (ESPI) system for measuring tensile properties under micro-tensile testing has been developed. The system consists of an optical system and an image processing system. In the optical system, optical components for measurement of in-plane deformation are arranged on the path of He-Ne laser. In the image processing system, the window-based program for acquiring speckle pattern interferometric image was developed and deformation in a small specimen is continuously evaluated during the test. Using this system, tensile strain of copper foil was measured during tensile testing. Tensile specimen had the thickness and width of 22 and 500 ${\mu}{\textrm}{m}$, respectively. Tensile properties, including the elastic modulus, yielding strength and tensile strength, of the copper were evaluated and also plastic exponent and coefficient in the Ramberg-Osgood relationship were evaluated from the stress-strain curve.

• 한국통신학회논문지
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• 제16권12호
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• pp.1266-1273
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• 1991

장거리 국간 선로에 포설된 단일모드 광섬유의 샘플집단과 모집단의 손실특성을 측정하였고, 구간(중계)거리분포를 측정 분석하였다. 접속손실을 포함한 평균손실은 130nm와 155nm에서 각각 0.55 0.05dB/km, 0.59 0.11/km로써 1550nm대역의 손실이 크게 나타났다. OTDR에 의한 손실특성 조사결과 1550nm대역의 손실증가 주 요인은 접속지점의 부적절한 여장처리에 따른 것이었다. 그리고 국내 평균중계거리는 24 7 km로써 31km 이하의 구간거리가 전체의 약 90%를 차지하고 있었다.

• Current Optics and Photonics
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• 제3권1호
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• pp.54-65
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• 2019

To develop a biomarker predicting tumor treatment efficacy is helpful to reduce time, medical expenditure, and efforts in oncology therapy. In clinics, microvessel density using immunohistochemistry has been proposed as an indicator that correlates with both tumor size and metastasis of cancer. In the preclinical study, we hypothesized that vascular morphometrics using optical coherence tomography angiography (OCTA) could be potential indicators to estimate the treatment efficacy of breast cancer. To verify this hypothesis, a 13762-MAT-B-III rat breast tumor was grown in a dorsal skinfold window chamber which was applied to a nude mouse, and the change in vascular morphology was longitudinally monitored during tumor growth and metronomic cyclophosphamide treatment. Based on the daily OCTA maximum intensity projection map, multiple vessel parameters (vessel skeleton density, vessel diameter index, fractal dimension, and lacunarity) were compared with the tumor size in no tumor, treated tumor, and untreated tumor cases. Although each case has only one animal, we found that the vessel skeleton density (VSD), vessel diameter index and fractal dimension (FD) tended to be positively correlated with tumor size while lacunarity showed a partially negative correlation. Moreover, we observed that the changes in the VSD and FD are prior to the morphological change of the tumor. This feasibility study would be helpful in evaluating the tumor vascular response to treatment in preclinical settings.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.300.2-300.2
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• 2016

Increasing of the demand for energy savings for buildings, thermal barrier films have more attracted. In particular, as heat loss through the windows have been pointed out to major problems in the construction and automobile industries, the research is consistently conducted for improving the thermal blocking performance for windows. The main theory of the technology is reflect the infrared rays to help the cut off the inflow of the solar energy in summer and outflow of the heat from indoors in winter to save the energy on cooling and heating. Furthermore, this is well known for prevent glare, reduces fading caused by harmful ultraviolet radiation and easy to apply on constructed buildings if it made as a film. In addition to these advantages, apply the transparent electrode to eliminate condensation by heating. Generally ITO is used as a transparent electrode, but is has a low stability in environmental factors. In this study, ITO and its alternative, ATO, is deposited by sputtering system and then the characteristic is evaluated each material based thermal barrier thin film. The optical property was measured on wide range of wavelength (200 nm 2500 nm) to know the transparency in visible wavelength and reflectivity in IR wavelength range. The electrical property was judged by sheet resistivity. Finally the changes of the temperature and current of the deposited film was observed while applying a DC power.