• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.6
• /
• pp.3429-3434
• /
• 2014

In the TFT-LCD(Thin Film Transistor-Liquid Crystal Display) panel manufacturing industry, SAMSUNG, a late entry, can catch up to leading first mover, SHARP. The changes the note, monitor, TV, and mobile markets in the TFT-LCD industry were studied using a system analysis method. In addition, the fast response time technology in SAMSUNG TFT-LCD technology was developed using the TRIZ method. For example, a new liquid crystal mixture of a wide view angle and fast response time were developed by doping a new high birefringence liquid crystal material in a base mixture using the contradiction method and su-field method of TRIZ. The response time of a new liquid crystal mixture was improved to approximately 60%(16.2ms with base LC mixture, 9.8ms with a new LC mixture).

• Korean Journal of Optics and Photonics
• /
• v.17 no.1
• /
• pp.94-98
• /
• 2006

An optical microphone based on a dual-core fiber collimator and a membrane type micromirror serving as an optical head and a reflective diaphragm respectively was implemented. The micromirror diaphragm is suspended by a thin silicon bar linked with a frame, thus it is subject to a displacement induced by acoustic waves. The optical head incorporating two collimators integrated in a single housing gives light to and receives it from the diaphragm, rendering the optical microphone structure simple and compact. This dual-core collimator having a slowing varying beam profile facilitates the initial alignment of the optical head with the diaphragm, especially the distance between them. For the assembled microphone, the static characteristics were investigated tofind the operation point defined as the optimum distance between the head and the diaphragm, and a frequency response with a variation of about $\pm$5 dB for the range of up to 3kHz was achieved.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.27 no.2
• /
• pp.183-189
• /
• 2007

Ultra precise processed parts are required together with the development of optoelectronics industry. As important parts of optoelectronics industry, there are ferrule of optical connector and lens for optical devices. In particular, the lens requires high reliability with high precision without including flaws. These optical modules need ultra precise processing in order to reduce the loss of light sources and various nondestructive inspections are carried out in the finishing stage to separate good and bad quality products. Therefore, it was analyzed through the characteristics of response of amplitude and resonant frequency according to the mass variations of aspheric lens that is used currently in laser printers.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.445.2-445.2
• /
• 2014

표면 조직화의 목적은 태양전지 표면에서의 입사되는 빛의 반사율을 감소 시키고, 웨이퍼 내에서 빛의 통과 길이를 길게 하며, 흡수되는 빛의 양을 증가시키는 것이다. 본 연구에서는 여러 가지 표면 조직화 공정 기술을 이용하여 표면 형상에 따른 광 변환 효율에 대해 연구하였으며, 셀을 제작하여 전기적 특성과 광학적 특성의 상관관계를 분석하였다. KOH를 이용한 표면 조직화, 산 증기를 이용한 표면 조직화, 반응성 이온 식각을 이용한 표면 조직화, 금속 촉매 반응을 이용한 표면 조직화 공정 기술을 이용하여 표면 조직화 공정을 진행하였다. 셀 제작 결과, 반사도 결과와는 상반되는 결과를 얻을 수 있었다. 표면 조직화 형상에 따른 셀 효율의 변화는 도핑 프로파일과 표면 재결합 속도의 변화 때문이라 생각되며 더 명확한 분석을 위해 양자 효율을 측정하여 분석을 시도하였다. 표면 조직화 공정 기술별 도핑 프로파일을 보면 KOH를 이용한 표면 조직화 공정을 제외한 나머지 표면 조직화 공정들의 도핑 프로파일은 불균일하게 형성되어 있는 것을 확인 할 수 있다. 양자 효율 측정 결과 단파장 대역에서 낮은 응답특성을 가지는 것을 확인 할 수 있었다. 그 이유는 낮은 반사도를 가지는 표면 조직화 공정의 경우 나노사이즈의 구조를 갖기 때문에 균일한 도핑 프로파일을 얻지 못해 전자, 정공의 분리가 제대로 이루어지지 못하였고 표면 재결합 속도증가의 원인으로 단락전류와 개방전압이 낮아져 효율이 떨어진 것으로 판단된다. 결과적으로 낮은 반사율을 갖는 표면 조직화 공정도 중요하지만 표면 조직화 공정 기술에 따른 균일한 도핑 프로파일을 갖는 공정을 개발한다면 단파장 응답도가 향상되어 단락전류밀도와 개방전압 상승효과를 얻을 수 있을 것이라 판단된다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.315.1-315.1
• /
• 2013

표면 조직화의 목적은 태양전지 표면에서의 입사되는 빛의 반사율을 감소 시키고, 웨이퍼 내에서 빛의 통과 길이를 길게 하며, 흡수되는 빛의 양을 증가시키는 것이다. 본 연구에는 습식, 건식 표면조직화 방법에 따른 표면 형상과 표면 반사도를 분석 하였으며, 셀을 제작하여 전기적 특성과 광학적 특성의 상관관계를 분석하였다. 표면 조직화 공정은 염기성 용액인 KOH를 이용한 식각 방법과 Ag를 이용한 metal-assisted 식각, 산증기를 이용한 식각, 플라즈마를 이용한 반응성 이온식각을 적용하여 제작하였다. 표면 반사율을 400~1000 nm 사이의 파장에서 측정하였으며 KOH를 이용하여 식각한 샘플이 9.11%의 표면 반사율을 가졌으며 KOH를 이용하여 식각한 표면에 추가로 metal-assisted 식각을 한 샘플이 2%로 가장 낮은 표면 반사율을 보였다. 표면 조직화 후 동일 조건으로 셀을 제작 하여 효율 측정 결과 Ag를 이용한 2단계 metal-assisted chemical 식각이 15.83%의 가장 낮은 광변환 효율을 보였으며 RIE를 이용한 2단계 반응성 이온 식각공정이 17.78%로 가장 높은 광변환 효율을 보였다. 이 결과는 반사도 결과와 일치 하지 않았다. 표면 조직화 모양에 따른 셀 효율의 변화는 도핑 프로파일과 표면 재결합 속도의 변화 때문이라 생각되며 더 명확한 분석을 위해 양자 효율을 측정하여 분석을 시도하였다. 측정 결과 단파장 대역에서 낮은 응답특성을 가지는 것을 확인 할 수 있었는데 그 이유는 낮은 반사도를 가지는 표면조직화 공정의 경우 나노사이즈의 구조를 갖기 때문에 균일한 도핑 프로파일을 얻지 못해 전자 정공의 분리가 제대로 이루어지지 못하였고 표면 재결합 속도증가의 원인으로 단락전류와 개방전압이 낮아져 효율이 떨어진 것으로 판단된다. 실험 결과 도핑 프로파일의 균일성은 셀 효율 개선을 위해 낮은 표면 반사율 만큼 중요하다는 점을 알게되었다. 낮은 반사율을 갖는 표면조직화 공정도 중요하지만 표면에 따른 균일한 도핑 프로파일을 갖는 공정을 개발한다면 단파장 응답도가 향상되어 단락전류밀도의 상승효과를 얻을 수 있을 것이라 판단된다.

• Journal of the Korea Computer Industry Society
• /
• v.2 no.4
• /
• pp.565-572
• /
• 2001

At the most recent years, laser medical instruments, laser applications and laser nuclear fusion need strong visible light and ultraviolet rays. Nonlinear optical devices, such as harmonic generators and parametric oscillators, provide a means of extending the frequency range of available laser sources. Frequency conversion is a useful technique for extending the utility of high-power lasers. It utilizes the nonlinear optical response of an optical medium in intense radiation fields to generate new frequencies. These progresses have been used to generate high-power radiation in all spectral regions, from the ultraviolet to the far infrared. Optical parametric oscillators and amplifiers generate two waves of lower frequency They are capable of generating a range of wavelengths from a single frequency source, in some cases spanning the entire visible and near infrared regions. Consequently, in order to obtain the green light, the pulsed Nd:YAG laser using multiple-mesh PFN(Pulsed Forming Network) method with Nonlinear optical device was adopted. We compared the current pulseshapes with the laser output energy, and conversion efficiency.

• Journal of Sensor Science and Technology
• /
• v.4 no.1
• /
• pp.3-8
• /
• 1995

n-ITO/p-PSL heterojunction photodetector have been fabricated on the Si wafer by using ITO(indium tin oxide) and PSL(porous silicon layer). They were anodized selectively by using silicon nitride and Ni-Cr/Au and were passivated by using ITO as well as being isolated by using mesa structure. With white light from 0 to 3000 Lux, the photocurrent varied linearly with incident light intensity. The reverse characteristics of fabricated devices were very stable up to a bias voltage of -40V and dark current density was about $40nA/mm^{2}$. When the device was exposed by Xe lamp whose wavelength range from 400nm to 1100nm, the maximum photo responsivity was about 0.6A/W between 600 and 700nm. Variation of the characteristics of fabricated devices after 5 weeks was negligible.

• Journal of Sensor Science and Technology
• /
• v.12 no.2
• /
• pp.57-65
• /
• 2003

When a vision chip for edge detection using CMOS process is designed, there is a necessity to implement local light adaptive-function for detecting distinctive features of an image at a wide range of light intensities. Local light adaptation is to achive the almost same output level by changing the size of receptive-fields of the local horizontal cell layers according to input light intensities, based on the lateral inhibitive-function of the horizontal cell. Thus, the almost same output level can be obtained whether input light intensities are much or less larger than background. In this paper, the horizontal cells using a resistive network which consists of p-MOSFETs were modeled and analyzed, and the local light adaptive-mechanism of the designed vision chip using the resistive network was verified.

• Korean Journal of Optics and Photonics
• /
• v.9 no.6
• /
• pp.423-427
• /
• 1998

Two wave mixing experiments in $LiNbO_3$, $BaTiO_3$ are carried out, and the characteristics as optical information processing device are investigated. Examined crystals are commonly used ones, such as 0.03% mol Ce-doped $BaTiO_3$, 0.03% mol Fe-doped $LiNbO_3$, and 6% mol MgO-doped $LiNbO_3$. $Ar^+$ ion laser is used as the writing beam, and He-Ne Laser is used as the reading beam. The recording-decay and erasing characteristics of diffraction gratings, the time constants, and also the angular selectivities are measured for each crystals and compared.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.18 no.2
• /
• pp.41-54
• /
• 2000

Photochemical modulation of Bragg-reflection wavelengths based on isomerization of an azobenzene (Azo) and subsequent change in reflectance was investigated in cholesteric liquid crystals (ChLCs) which reflect light in visible wavelength region. Irradiation at 366 nm, which causes an efficient transcis isomerization of Azo, led to change in reflected color of ChLCs toward shorter wavelengths with a concomitant lowering of phase transition. Reversible change in color was induced all-optically by alternate irradiation at effective wavelengths for reversible isomerization of Azo. A considerable variation in reflectance was also observed when the photoinduced change in color was measured by a probe light with the same handedness as the ChLCs. The spectral Position of selective light reflection in the initial states played an important role to produce a normal-mode and a reverse-mode switching in photoinduced modulation of reflectance of the ChLCs with respect to the probe light.