• 대한의용생체공학회:의공학회지
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• 제18권4호
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• pp.499-505
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• 1997

본 연구에서는 생체조직의 흡수계수와 산란계수를 비침습적으로 측정하는 방법에 관하여 연구하였다. 피코초 영역의 펄스폭을 갖는 레이저광으로 조직을 조사하고 산란반사된 빛을 시간상관 단일 광자 계수법을 이용하여 피코초 시간영역에서 측정하였다. 측정된 시간분해 반사율의 최대치에 이르는 시간 및 나중소멸부분의 점근선의 기울기로부터 계산되는 값과 디컨블루션방법에 의한 곡선맞춤으로 얻은 값을 비교하여 서로 잘 일치함을 확인하였다. 매질의 산란이 커질수록 흡수가 작을수록 근사식은 더 잘 맞으므로 가시광선부터 근적외선의 파장영역에서 흡수에 비해 산란이 매우 큰 생체조직의 광특성을 비침습적으로 측정하는 중요한 방법이 될 수 있다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.235-239
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• 1996

In recent years, the optical properties of multiple-scattering media like tissue have been studied for their potential applications in medicine. In this work the optical properties of multiple scattering media were investigated using the time-resolved reflectance measurement. The reflected light was measured by time-correlated single photon counting system. The transport scattering and absorption coefficient are related to the initial rapid decay and the subsequent decay in reflected light, respectively. Also the optical properties of the samples were measured by conventional method, ie., using continuous wave light. When the distance between the light source and the detector is over 8mm, the optical coefficient can be measured accurately using the suggested method.

• 대한기계학회논문집B
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• 제27권2호
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• pp.188-196
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• 2003

Liquid-assisted cleaning technology utilizing a nanosecond laser pulse is effective for removing submicron particulates from a variety of solid substrates. In the technique, saturated vapor is condensed on a solid surface to form a thin liquid film and the film is evaporated explosively by laser heating. The present work studies the role of liquid-film evaporation in the cleaning process. First, optical interferometry is employed for in-situ monitoring the displacement of the laser-irradiated sample in the cleaning process. The experiments are performed for estimating the recoil force exerted on the target with and without liquid deposition. Secondly, time-resolved visualization and optical reflectance probing are also conducted for monitoring the phase-change kinetics and plume dynamics in vaporization of thin liquid layers. Discussions are made on the effect of liquid-film thickness and dynamics of plume and acoustic wave. The results confirm that cleaning force is generated when the bubble nuclei initially grow in the strongly superheated liquid.

• 전기학회논문지
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• 제60권5호
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• pp.1049-1054
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• 2011

Color is discerned due to the reflectance of object and its hue is determined by the Ratio of RGB spectrum. The aim of this study is to evaluate the Color information using by the optical system in terms of convenience and simplicity. Firstly, the differential Ratio of RGB is evaluated by photodiode Sensor which achieves a high efficiency with quick tranducer output. To extract the information of RGB Ratio, light emitting diode is built in Color sensing system with photodiode. Our proposed method is very economical, simple, and convenient. Our results can be applied to confirm the accurate information of Color in the research environments and commercial purposes. Thus RGB information can be determined subjectively and thus, the inherent characteristic of Color will be revealed precisely and its related features can be resolved in a real time mode.