• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1665-1666
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• 2006

TFT-LCD(Thin Film Transistor Liquid Crystal Display)는 표시장치로서 실용화된 후 많은 상품에 적용중이다. 그러나, LCD는 자체 발광능력이 없으므로 그후면에서 LCD 화면을 밝혀주는 BLU(Backlight Unit)를 필요로 한다. BLU는 내부 광원으로 밝기가 균일한 평면광을 만들어 LCD 화면을 균일하게 면조사하는 역할을 한다. LCD가 적용되는 분야중 Note PC에는 광원으로 CCFL(Cold Cathode Fluorescent Lamp)가 적용되어 왔지만, 최근 고휘도, 박형화, 저소비 전력을 달성하기 위해 CCFL로는 한계가 있어 LED(Light Emitting Diode)를 적용한 BLU를 제작하기 위한 연구가 진행되고 있다. 본 연구에서는 점광원인 LED 적용한 LED에 있어서 요구되는 휘도 균일성을 향상시키기 위해서는 LED광원이 적용된 BLU의 외관 품질 향상을 위한 도광판 입광부 구조 최적화를 광추적 Simulation을 통해 예측하고 향상시킬 수 있는 구조를 제안한다. Simulation결과, 외관품질 개선을 위해 도광판 입광면에 130도의 Serration과 휘도를 향상하기 위해 도광판 밑면에 렌즈 형상의 바 구조를 도출해 적용한 결과 외관품질향상과 휘도향상을 얻었다.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.20-22
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• 2004

유기 EL(Organic Light Emitting diode : OLED)은 자체발광 소자로서 액정 디스플레이(Liquid Crystal Display)에 비해 빠른 응답속도, 넓은 시야각 등의 뛰어난 화질 표현이 가능하다. 구동 박막 트랜지스터(TFT)의 전류가 OLED의 휘도를 결정하므로, 고품질의 영상을 위해 미세한 TFT 전류 조절 능력이 매우 중요하다. 비정질 실리콘(a-Si) TFT는 그레인 구조를 갖는 다결정 실리콘(poly-Si) TFT에 비해 균일한 전기적 특성을 나타내지만, 장시간 구동에 따른 문턱전압의 열화가 발생한다. 본 논문에서는 상기의 문제점을 최소화하기 위하여 positive bias에 의한 열화를 negative bias로 어닐링하는 구동방법을 제안하였다. 본 회로는 2개의 게이트 선택 신호와 6개의 a-Si TFT로 이루어져 있다. 실험 결과를 통해 추출된 소자 parameter를 바탕으로 제안된 회로의 simulation을 수행 및 검증하였다. 본 회로는 a-Si TFT에서 발생하는 문턱전압 열화 등의 신뢰성 문제를 감소시킨다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.502-503
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• 2005

본 연구에서는 TFT-LCD(Thin Film Transistor-Liquid Crystal Display)의 배경광원인 BLU(Back Light Unit)의 고효율화, 고품질화를 통한 원가 절감을 달성하기 위해 BLU의 대표적 핵심부품중에 하나인 프리즘 시트를 사용하지 않는 구조의 MNT용 BLU를 개발하는데 목적을 두었다. 고효율의 BLU를 만들기위하여 17인치 BLU의 도광판의 상, 하면에 Prism 형상을 구현하였으며, 광학적 시뮬레이션을 통하여 먼저 가능성을 검토하였고, UV에 반응하는 Resin을 경화시키는 방법을 이용하여 일반 도광판에 프리즘형상을 각인(Imprint)시키는 방법으로 실물을 재현하였다. 실험 결과 프리즘 시트를 사용하지 않는 구조의 MNT용 17인치 BLU에서 중심휘도 4,984nit, 균일도 70% 달성하였다.

• Transactions on Electrical and Electronic Materials
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• v.9 no.5
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• pp.198-201
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• 2008

The electro-optical (EO) characteristics of the one-side rubbing twisted nematic (TN) - liquid crystal display (LCD) on the polyimide (PI) surface with one-side ion beam (IB) irradiation were successfully studied. The good LC alignment for the one-side rubbing TN-LCD on the PI surface with one-side IB irradiation was observed. The suitable transmittance-voltage curves for the one-side rubbing TN-LCD on the PI surface with one-side IB irradiation were measured. Also, the good response time characteristics of the one-side rubbing TN-LCD on the PI surface with one-side IB irradiation were measured. The fast response time can be achieved for the one-side rubbing TN-LCD on the PI surface with one-side IB irradiation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.10
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• pp.822-833
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• 2011

A Xe plasma flat lamp, which has been noticed as a new eco-friendly LCD (liquid crystal display) backlight, requires the improvement of the luminance and the luminous efficiency although it has several advantages. To improve the performance of a lamp, it is necessary to understand the effects of discharge variables on the luminous characteristics of the lamp. Since it is difficult to diagnose a lamp discharge experimentally, the numerical analysis can be used instead. In this study, the luminous characteristics of a planar type Xe plasma flat lamp were analyzed with the variation of an input voltage and a pulse frequency. The numerical analysis of a lamp discharge was then performed using a RCT (relaxation continuum) model and a LFA (local field approximation) model. The comparison with the experimental results showed that the RCT model is valid for the numerical analysis of the flat lamp. The numerical analysis also showed that the modifications of a high frequency component and a voltage falling rate in the input voltage waveform could improve the luminous characteristics of the lamp.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.172-172
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• 2010

In the area of optoelectronic devices based on GaN and related ternary compounds, the two-dimensional system like as quantum wells (QWs) has been investigated as an effective structure for improving the light-emitting efficiency. Generally, the quantum well active regions in III-nitride light-emitting diodes grown on conventional c-plane sapphire substrates have critical problems given by the quantum confined Stark effect (QCSE) due to the effects of strong piezoelectric and spontaneous polarizations. However, the QWs grown on nonpolar templates are free from the QCSE since the polar-axis lies within the growth plane of the template. Also the unique characteristic of linear polarized light emission from nonpolar QW structures is attracting attentions because it is proper to the application of back-light units of liquid crystal display. In this study, we characterized optical properties of the a-plane InGaN/GaN QW structures by temperature-dependent photoluminescence (TDPL) measurements. From the photoluminescence (PL) spectrum measured at 300 K, green emission centered at 520 nm was observed for the QW region. Since indium incorporation on nonpolar QWs is lower than that on c-plane, this high indium-doping on a-plane InGaN QWs is not common. Therefore, the effect of high indium composition on optical properties in a-plane InGaN QWs will be extensively studied.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.84-89
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• 2021

Indium tin oxide (ITO) transparent electrodes, which are used to manufacture organic light-emitting diodes, are used in light-emitting surface electrodes of display EL panels such as cell phones and TVs, liquid crystal panels, transparent switches, and plane heating elements. ITO is a major component that consists of indium and tin and is advantageous in terms of obtaining sheet resistance and light transmittance in a thin film. However, the optical performance of devices decreases with an increase in its thickness. A digital holography system was constructed and measured for the step measurement of the ITO thin film, and the reliability of the technique was verified by comparing the FE-SEM measurement results. The error rate of the step difference measurement was within ±5%. This result demonstrated that this technique is useful for applications in advanced MEMS and NEMS industrial fields.

• Journal of Preventive Medicine and Public Health
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• v.52 no.4
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• pp.265-271
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• 2019

Objectives: The Samsung Ombudsperson Commission was launched as an independent third-party institution following an agreement among Samsung Electronics, Supporters for Health and Right of People in Semiconductor Industry (Banolim in Korean, an independent NGO), and the Family Compensation Committee, in accordance with the industry accident prevention measure required by the settlement committee to address the issues related to employees who allegedly died from leukemia and other diseases as a result of working at Samsung's semiconductor production facilities. Methods: The Commission has carried out a comprehensive range of activities to review and evaluate the status of the company's occupational accidents management system, as well as occupational safety and health risk management within its facilities. Results: Based on the results of this review, termed a comprehensive diagnosis, the Commission presented action plans for improvement to strengthen the company's existing safety and health management system and to effectively address uncertain risks in this area going forward. Conclusions: The Commission will monitor the execution of the suggested tasks and provide advice and guidance to ensure that Samsung's semiconductor and liquid crystal display production lines are safer.

• Journal of Sensor Science and Technology
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• v.32 no.2
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• pp.118-123
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• 2023

This study presents sensor system for autonomous mobile robot capable of floor-to-floor self-navigation. The robot was modified using the Turtlebot3 hardware platform and ROS2 (robot operating system 2). The robot utilized the Navigation2 package to estimate and calibrate the moving path acquiring a map with SLAM (simultaneous localization and mapping). For elevator boarding, ultrasonic sensor data and threshold distance are compared to determine whether the elevator door is open. The current floor information of the elevator is determined using image processing results of the ceiling-fixed camera capturing the elevator LCD (liquid crystal display)/LED (light emitting diode). To realize seamless communication at any spot in the building, the LoRa (long-range) communication module was installed on the self-navigating autonomous mobile robot to support the robot in deciding if the elevator door is open, when to get off the elevator, and how to reach at the destination.

• Journal of Technologic Dentistry
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• v.45 no.3
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• pp.74-80
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• 2023

Purpose: This study aimed to evaluate the fit of the anterior and posterior teeth printed using two light-curing three-dimensional (3D) printers. Methods: Anterior and posterior single crowns were designed using dental software and were printed using 2 types of 3D printers, liquid crystal display (LCD) and digital light processing (DLP) (n=40). After the printed crown was scanned again from inside and outside, the prepared teeth were evaluated using a 3D program. To compare the root mean square (RMS) results among groups (α=0.05), the one-way analysis of variance and Tukey's test were used. Results: No statistically significant difference was found between the mean RMS values of the anterior and posterior teeth (p>0.05). However, as a result of comparing the internal, external, and tooth shapes, the DLP group showed significantly low errors in the inner and outer surfaces than LCD group (p<0.05). Conclusion: In terms of clinical acceptance standard of 100 ㎛, the fit of the anterior and posterior teeth fabricated using LCD and DLP was clinically acceptable.