• 반도체디스플레이기술학회지
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• 제21권3호
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• pp.101-104
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• 2022

Mist-CVD is known to have advantages of low cost and high productivity compared to ALD and PECVD methods. It is capable of reacting to the substrate by misting an aqueous solution using ultrasonic waves under vacuum-free conditions of atmospheric pressure. In particular, Ga₂O₃ is regarded as advanced power semiconductor material because of its high quality of transmittance, and excellent electrical conductivity through N-type doping. In this study, Computational Fluid Dynamics were used to predict the uniformity of the thin film on a large-area substrate. And also the deposition pattern and uniformity were analyzed using the flow velocity and particle tracking method. The uniformity was confirmed by quantifying the deposition cross section with an FIB-SEM, and the consistency of the uniformity prediction was secured through the analysis of the CFD distribution. With the analysis and experimental results, the match rate of deposition area was 80.14% and the match rate of deposition thickness was 55.32%. As the experimental and analysis results were consistent, it was confirmed that it is possible to predict the deposition thickness uniformity of Mist-CVD.

• 한국산학기술학회논문지
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• 제9권4호
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• pp.878-885
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• 2008

최근에 많은 수요와 각광을 받고 있는 디스플레이 장치에서 CRT는 곡면이며 무겁고 큰 부피 때문에 LCD, PDP, OLED와 같은 평판디스플레이(FPD)로 대체되고 있다. FPD는 $0.6\sim0.8mm$ 두께의 대면적 글래스에 여러 공정을 거친 후에 최종 제품 규격으로 절단하여 제작하기 때문에 글래스의 면적이 크면 클수록 FPD의 생산성이 높다는 밀접한 관계를 갖는다. 따라서 FPD 제조 업계에서는 글래스 면적을 증가시키기 위하여 노력하고 있으며, 예를 들면, 현재 8세대 LCD인 경우 약 $2,200mm\times2,600mm$의 면적을 가진다. 이러한 글래스를 이송하는 대표적인 장치로서 공기부상 컨베어시스템은 압축공기를 이용해서 FPD용 대면적 글래스 등을 약 $0.3\sim0.5mm$ 정도 부상시켜 비접촉으로 이송할 수 있는 장치이다. 이 때 글래스와 다공질판 표면 사이의 공기 유동이 모델링되고 해석되며, 이것으로부터 글래스의 공기부양 조건이 예측될 수 있다. 글래스를 이송시 전기공급 중단에 의하여 압축공기가 공급되지 않아 부상판과 접촉이 발생하였을 때, 자기윤활 특성을 가진 다공질판 위의 글래스는 1mm 홀을 많이 가진 사각덕트 부상판 위의 글래스와 조사, 비교된다.

• Journal of Information Display
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• 제2권3호
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• pp.48-53
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• 2001

Carbon nanotube emitters, prepared by screen printing, have demonstrated a great potential towards low-cost, largearea field emission displays. Carbon nanotube paste, essential to the screen printing technology, was formulated to exhibit low threshold electric fields as well as an emission uniformity over a large area. Two different types of triode structures, normal gate and undergate, have been investigated, leading us to the optimal structure designing. These carbon nanotube FEDs demonstrated color separation and high brightness over 300 $cd/m^2$ at a video-speed operation of moving images. Our recent developments are discussed in details.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 추계학술대회
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• pp.99-102
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• 2004

Display process has adopted RCA clean, being applied to large area and coped with environmental issue for last ten years. However, the approaching concept of ozonized, hydrogenised, or electrolyzed water cleaning technologies is within RCA clean paradigm. In this work, only electrolyzed anode water was applied to clean particles and organics as well as metals based on Pourbaix concept, and as a test vehicle, MgO particles were introduced to prove the new concept. The electrolyzed anode water is very oxidative with high oxidation reduction potential(ORP) and low in pH of more than 900mV and 3.1, respectively. MgO particles were immerged in the anode water and its weight losses due to dissolution were measured with time. Weight losses were in the ranges of 100 to 500 micrograms in 250m1 anode waters depending on their ORP and pH. Therefore it was concluded that the cleaning radicals in the anode water was at least in the range of 1 to 5E20 ea per 250 ml anode water equivalent to IE18 ea/cm3. Hence it can be assumed that the anode water be applied to display cleaning since 1E10 to IE15 ea/cm3 ranges of contaminants are being treated. In addition, it was observed that anode water does not develop micro-roughness on hydrophobic surface while it does on the native silicon oxide.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.211-211
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• 2000

Carbon nanotubes (CNTs) have been spotlighted as one of promising field emission displays(FEDs). For the first time, to authors knowledge, we have developed the 9" color CNT-FEDs with the resolution of 240x576 lines. The 9" CNT-FEDs with diode-type and triode-type structures are presented. The well-dispersed CNT paste was squeezed onto the metal-patterned cathode glass. For the anode plate, the Y2O2S:Eu, ZnS:Ag,Cl low-voltage phosphors were printed for red, green, and blue colors, respectively. The vacuum-packaged panel maintained the vacuum level of 1x10-7 Torr. The uniform moving images vacuum-packaged panel maintained the vacuum level of 1x10-7 Torr. The uniform moving images were demonstrated at 2 V/um. High brightness of 800, 200, and 150cd/m2 was observed on the green, red, and blue phosphors at V/um, respectively. Field emission characteristics of a triode-type CNT-FED were simulated using a finite element method. the resultant field strength on the cathode was modulated by gate bias and emitted electrons were focused on the anode. A relatively uniform emission image was experimentally achieved at the 800V anode. A relatively uniform emission image was experimentally achieved at the 800V anode and the 50-180 V gate biases. Energy distribution of electrons emitted from CNTs was measured using an energy analyzer. The maximum peak of energy curve corresponded to the Fermi energy level of CNTs. The whole fabrication processed of CNT-FEDs were fully scalable and reproducible. Our CNT-FEDs has demonstrated the high potential of large-area and full-color applications with very low cost fabrication and low power consumption.

• 한국산학기술학회논문지
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• 제20권1호
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• pp.290-296
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• 2019

차량용 HUD는 자동차 전면 유리창에 안전 운전과 편의 운전 관련 다양한 정보를 표시해 주는 장치로 중요한 역할을 수행한다. 본 논문에서는 증강현실 기술에 적용이 가능한 대면적 비구면 자유형상 미러를 가공하기 위해 초정밀 가공기를 이용하여 가공을 실시하였고 그 결과를 측정하였다. 초정밀 다이아몬드 절삭은 정밀도가 높을 뿐만 아니라 표면 거칠기와 잔류 응력을 낮게 할 수 있어서 우수한 표면 무결성을 갖는 고급 부품의 생산에 유리하다. 또한 비구면 자유 형상의 몰드를 사용함으로써 광학 전달 함수의 개선, 왜곡 경로의 감소 및 특수 이미지 필드 곡률의 실현과 같은 장점을 얻을 수 있다. 이와 같은 비구면 자유형상 금형을 가공하기 위한 방법으로는 초정밀가공기를 이용한 다이아몬드 절삭 방법을 사용하였으며, 제작된 비구면 자유형상 미러 금형의 평가는 비구면 형상 측정기를 이용하여 실시하였다. 이러한 방법에 의해 $1{\mu}m$ 이하의 형상 정밀도(PV)와 $0.02{\mu}m$ 이하의 표면 거칠기(Ra)를 갖는 비구면 자유형상 금형을 제작할 수 있었다.

• 인터넷정보학회논문지
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• 제10권3호
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• pp.131-140
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• 2009

최근 정보의 시각화를 연구하는 쪽에서는 그래프의 시각화에 많은 관심을 갖고 있는데, 그 중 사회망 (social network)의 시각화에 특히 집중하고 있다. 하지만 아직까지 사회망 내에서의 정보의 흐름을 시각화하는 방법에 대해서는 깊이 있는 연구가 진행되지 않고 있었다. 정보의 흐름은 사회망의 구조와 밀접하게 연관되어 있고, 또한 실제적인 상호관계의 동적인 구성을 보여주기 때문에 사회망의 구조적 특징보다 더 유용한 정보를 담고 있다. 따라서 정보의 흐름을 시각화하는 것은 매우 중요하다. 본 논문에서는 초대형 사회망을 마치 온라인 지도서비스를 이용하듯이 탐색하고, 사회망 내에서의 정보의 흐름을 관찰할 수 있는 방법에 관하여 제안한다. 이를 위하여 (i) 초대형 사회망을 2차원 그래프에 맵핑하는 방법과, (ii) 줌-인, 줌-아웃 기능 등을 활용하여 그래프를 탐색하는 방법, 그리고 (iii) 효율적인 질의 처리 프레임웍을 구축하는 방법을 고안하였다. 이 방법들을 이용하여 초대형 사회망을 제한적인 공간과 한정된 자원을 이용하여 효과적으로 표현할 수 있고, 이에 기반을 두어 사회망에서의 정보의 흐름을 시각화할 수 있게 된다.

• Journal of Nutrition and Health
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• 제30권6호
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• pp.704-714
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• 1997

The purpose of this survey was to investigate the operation and the environment of foodservice in elementary schools nationwide. A questionnaire about foodservice management to practice and foodservice operation was mailed to dietitians of each school . Of the 1, 416 schools that participated in this survey, 388 schools were selected for analysis. The main results of this study are as follows. More schools in small cities . Education levels of dietitians were significantly different from area to area. Mean total length of employment for dietitians at school foodservice was 4.7 years and varied significantly by area and the type of foodservice system. Foodservice has been operated for 2-5 years in most of schools. Schools in large cities served more people than those in small cities and rural areas. Also , schools adapting conventional foodservice system served more people than those adapting commissary or joint management system. Foodservice expense also veried significantly by area and foodservice systems. Mean foodservice expense per meal were significantly higher in schools adapting commissary system than those adapting other systems. Most schools employed dietitians, cooks, and assistant cooks, but not engineers not drivers. Mothers of students were working voluntarily. The degree of participation by mothers in cooking , serving , and cleaning was higher in schools of small cities and rural areas than those in large cities, in schools adapting commissary or joint management system than those adapting conventional system. Education and training ranked as personnel management had one of the hardest tasks. Education and training of employees were also difficult for dietitians, especially in commissary or joint management systems. Percentage of schools having separate lunchroom was higher in small cities rural areas than in large cities, in joint management or commissary system than conventional system. Most difficult matters in serving was the portion control. Over 40% of schools did not use standard recipes. Menu cycles were shorter in schools in small cities and rural areas which adapted the joint management system than area other schools. Except refrigerators, thermos , display racks, sterilizers, sinks, worktables, and table, all other equipment were insufficient in most of schools. More than half of the schools didn't have rice cookers, flatware racks, and distributing carts which are stated plainly in detailed enforcement regulations for school foodservice. Cooking equipments were described as the most needed by dietians. According to the results of this survey, many and urgent problems need to be addressed improve the quality of school foodservice . Lunchroom setups, effective personnel management and expenses, recipes standardization, serving size control and regular checking and repairing of equipments are all problems to be addressed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.242-242
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• 2012

Transparent oxide semiconductors are increasingly becoming one of good candidates for high efficient channel materials of thin film transistors (TFTs) in large-area display industries. Compare to the conventional hydrogenated amorphous silicon channel layers, solution processed ZnO-TFTs can be simply fabricated at low temperature by just using a spin coating method without vacuum deposition, thus providing low manufacturing cost. Furthermore, solution based oxide TFT exhibits excellent transparency and enables to apply flexible devices. For this reason, this process has been attracting much attention as one fabrication method for oxide channel layer in thin-film transistors (TFTs). But, poor electrical characteristic of these solution based oxide materials still remains one of issuable problems due to oxygen vacancy formed by breaking weak chemical bonds during fabrication. These electrical properties are expected due to the generation of a large number of conducting carriers, resulting in huge electron scattering effect. Therefore, we study a novel technique to effectively improve the electron mobility by applying environmental annealing treatments with various gases to the solution based Li-doped ZnO TFTs. This technique was systematically designed to vary a different lithium ratio in order to confirm the electrical tendency of Li-doped ZnO TFTs. The observations of Scanning Electron Microscopy, Atomic Force Microscopy, and X-ray Photoelectron Spectroscopy were performed to investigate structural properties and elemental composition of our samples. In addition, I-V characteristics were carried out by using Keithley 4,200-Semiconductor Characterization System (4,200-SCS) with 4-probe system.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.241-244
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• 2003

The world largest 21.3" LTPS LCD has been successfully developed using SLS crystallization technology. Successful integration of gate circuit, transmission gate and level shifter was performed in a large area uniformly. Uniformity and high performance from high quality grains of SLS technology make it possible to come true a uniform large size LTPS TFT-LCD with half number of data driver IC's used in typical a-Si LCD. High aperture ratio of 65% was obtained using an organic inter insulating method, which lead a high brightness of 500cd/cm2.