• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.141-142
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• 2009

• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.3
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• pp.97-104
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• 2011

The storing ability of information of optical disks directly depends on the physical property of recording unit cells. It means that the degradation of optical disks ultimately causes the loss of the physical and chemical properties of recording unit cells and leads also information, too. We investigated the degradation and life time of optical disks which tell us the longevity of the preservation of information. Optical disks were aged using the accelerated aging system and studied by optical reflectivity spectroscopy and atomic force microscopy(AFM), and the preservation environment of electronic media in National central library of Korea also were analysed. Results show that the double reflective coated optical disks have good preservation of recording information but revealed some deformation of dye area in the AFM images. It means that we should include the mechanical and chemical degradation of the optical disks in the life time expectation evaluation.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.161-161
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• 2010

InAsSb alloy system 은 HgCdTe 를 대체하는 적외선 광소자 및 검출기 등에 응용이 가능한 유망한 물질이지만 정확한 유전함수 및 전이점의 연구는 미흡한 실정이다. 본 연구에서는 타원 편광 분석법을 이용하여 1.5 ~ 6 eV 의 분광 영역에서 As 조성비를 각기 (x = 0, 0.127, 0.337, 0.491, 0.726 및 1.00) 다르게 한 $InAs_xSb_{1-x}$ alloy의 유전함수를 측정하였다. 또한 표면에 자연산화막을 제거하기 위하여 Methanol 과 DI Water 로 표면을 세척 한 후 $NH_4OH$, Br in Methanol, HCl 등으로 적절한 화학적 에칭을 하여 산화막을 제거함으로서 순수한 InAsSb 의 유전함수를 측정할 수 있었다. 측정된 InAsSb 유전함수를 Standard analytic critical point line shape 방법으로 As 조성비에 따른 에너지 전이점을 얻을 수 있었다. 또한 얻어진 에너지 전이점 값을 이용하여 linear augmented Slater-type orbital 방법으로 전자 밴드 구조 계산을 하였고, 이를 바탕으로 $E_0$, $E_1$, $E_2$ 전이점 지역의 여러 전이점 ($E_1$, $E_1+\Delta_1$, $E_0'$, $E_0'+\Delta_0'$, $E_2$, $E_2+\Delta_2$, $E_2'$, $E_2'+\Delta_2$, $E_1'$) 의 특성을 정확히 정의할 수 있었다. 또한 As 조성비가 증가하면서 $E_2$, $E_2+\Delta_2$, $E_2'$, $E_2'+\Delta_2$ 전이점들이 서로 교차 되는 것을 발견하였고, 저온에서만 관측이 가능하였던 InSb 의 두 saddle-point (${\Delta_5}^{cu}-{\Delta_5}^{vu}$, ${\Delta_5}^{cl}-{\Delta_5}^{vu}$)를 상온에서 찾아내었다. 타원 편광 분석법을 이용한 전이점 연구 및 물성 분석은 InAsSb alloy 의 광학적 데이터베이스를 확보하는 성과와 더불어 새로운 디바이스기술 및 광통신 산업에도 유용한 정보가 될 것이다.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.229-234
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• 2007

Diffuse optical tomography (DOT) is a relatively new medical imaging modality which uses near infrared light to image large-sized tissues noninvasively. We constructed a frequency-domain DOT system to measure the optical properties of optical phantoms and human tissues. The FD-DOT uses the intensity-modulated infrared light source that illuminates the biological tissues. The phase shift and modulation changes at each detector site are separately processed to measure the optical properties. The absorption and scattering coefficients are separately estimated using inverse algorithms.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.169-174
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• 2006

The outstanding mechanical property of optical fiber and the merits of acoustic emission sensing technique are unified for novel sensor system. The generated ultrasonic wave from piezoelectric generator are propagated along the optical fiber and also sensed. The propagated wave can be influence by external pressure on the optical fiber or environmental circumstance. The optical fiber sensor using ultrasonic wave has advantages compare with existing sensor system. In this study, the sensitivity of the optical fiber sensor is experimentally investigated. As the applications of the optical fiber sensor system using piezoelectric ultrasonic waves, the point load on the optical fiber is measured and the monitoring system for the void fraction of two phase flows is developed. The experimental results show the linear relationship between sensed voltage and void fraction.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.79-81
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• 1990

Temperature distribution of laser diode chip mounted on ideal heat kink was calculated by numerical analysis. In numerical analysis, infinite difference method and Gauss-Scidel iteration was adopted on the basis of two dimensional heat conduction phenomena. As a result, temperature increase of active medium of laser diode driven at 60mA was calculated to be 1.47$^{\circ}C$

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.14-15
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• 2000

We study the microwave characteristics of traveling-wave photodetector using the finite-difference time-domain method. We present two parameters for design, the width of PIN region and the thickness of i-layer, and analyze TWPD's property in frequency domain.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.148-149
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• 2005

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.985-987
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• 2004

A plastic substrate for flexible display is developed. The gas barrier property in the substrate is improved through depositing metal and metal oxide multi layer on plastic film by PVD process. The metal/metal-oxide multiplayer on plastic film shows excellent gas barrier property and optical property.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.489-493
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• 2016

In this study, the effect of vanadium oxide ($V_2O_5$) content and pre-sintering atmosphere on sealing property of glass frit that consisted of $V_2O_5-BaO-ZnO-P_2O_5-TeO_2-CuO-Fe_2O_3-SeO_2$ was investigated by XPS (X-ray photoelectron spectroscopy). The content of V2O5 was changed to 15, 30, and 45 mol%, and the pre-sintering was carried out in air and $N_2$ condition, respectively. XPS analysis conducted before and after laser irradiation with identical sample. Before laser treatment, glass frits that were pre-sintered at air condition showed both $V^{4+}$ and $V^{5+}$, but the valence state was changed to $V^{5+}$ after laser irradiation when the glass frits contained 30 and 45 mol% $V_2O_5$; this change led to non-adhesive property. On the other hand, glass frits that were pre-sintered at $N_2$ condition exhibited only $V^{4+}$ and it showed fine adhesion irrespective of the $V_2O_5$ content. As a result, the existence of $V^{4+}$ seems to be a major factor for controlling the adhesive property of glass frit for laser sealing.