• 한국인쇄학회지
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• 제29권3호
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• pp.105-124
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• 2011

TFT-LCD consists of LCD panel on the top, circuit unit on the side and BLU on the bottom. The recent development issues of BLU-dependent TFT-LCD have been power consumption minimization, slimmerization and size maximization. As a result of this trend, LED is adopted as BLU instead of CCFL to increase brightness and to reduce thickness. In liquid crystal displays, the light efficiency is below 10% due to the loss of light in the path from a light source to an LCD panel and presence of absorptive polarizer. This low efficiency results in low brightness and high power consumption. One way to circumvent this situation is to use a reflective polarizer between backlight units and LCD panels. Since a nano-wire grid polarizer has been known as a reflective polarizer, an idea was proposed that it can be used for the enhancement of the brightness of LCD. The use of reflective polarizing film is increasing as edge type LED TV and 3D TV markets are growing. This study has been carried out to fabrication of the nano-wire grid polarizer(NWGP) and investigated the brightness enhancement of LCD through polarization recycling by placing a NWGP between an c and a backlight unit. NWGPs with a pitch of 200nm were fabricated using laser interference lithography and aluminum sputtering and wet etching. And The NWGP fabrication process was using by the UV imprinting and was applied to plastic PET film. In this case, the brightness of an LCD with NWGPs was 1.21 times higher than that without NWGPs due to polarization recycling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1657-1658
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• 2006

An external electrode fluorescent lamps (EEFLs) have the advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Studies on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter. To solve these problems of CCFL, EEFL (External Electrode Fluorescent Lamp) is introduced. Because electrode of EEFL is on the outer surface of discharge tube, the electrode is perfectly prevented from the sputtering by accelerated ions. And it is possible to drive the many CCFLs at the same time, because EEFL shows the positively resistant characteristic. But EEFL has the large non-radiative power loss in sheath. In this study the novel electrode structure was introduced in order to reduce non-radiative power loss in sheath of EEFL. The novel electrode structure comes from the idea to combine conceptually capacitive discharge with inductive discharge. Thus, this study verifies the change in the optical characteristics according to the change in electrode structure through a Maxwell's electromagnetic field simulation and examines the relationship between the change in the EEFL electrode structure and brightness by measuring the optical characteristics.

• 에너지공학
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• 제28권3호
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• pp.26-33
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• 2019

ATLAS와 LSTF 장치에서 수행된 저온관(CL) 파단 13% 및 17% IBLOCA 대응실험들을 비교하고 특히, 핵심 관심 인자인 노심 첨두피복온도(PCT)에 대하여 비교 검토하고 아울러 주요 열수력 현상에 대하여 토론하였다. 비교.검토에서 두 건의 CL 파단 IBLOCA 대응실험들은 PCT 거동에 있어서 꽤 큰 차이를 보이고 있는 것을 확인하였는데 이는 두 장치의 척도 차이로 인한 왜곡현상을 벗어나는 경향을 보이고 있다는 점에서 두 장치의 원자로냉각재계통에 대한 자세한 설계 비교를 수행하였다. 이에 두 장치 사이에 핵연료조정판(FAP) 설계에 있어서 차이가 있다는 점을 확인하였다. 이에 따라 IBLOCA 사고시 Reflux 응축수의 노심 유입에 중요한 역할을 하는 CCFL 관련 무차원직경 값에서도 두 장치에서 매우 다른 차이를 보이고 있다는 점에서 CL 파단 IBLOCA 대응실험에서의 PCT 거동의 현격한 차이를 설명할 수 있는 원인일 수 있는 인자라는 것을 발견하였다. 향후 관련 설계 차잇점을 근거로 더 자세한 검토와 분석을 통해 관련 현상을 이해할 수 있을 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.3973-3982
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• 2023

As for two-phase flow in rectangular channels, the flow regimes especially like churn-turbulent and annular flow are significant for the physical problem like Countercurrent Flow Limitation (CCFL). In this study, the rectangular channels with cross-sections of 4 × 66 mm, 6 × 66 mm, 8 × 66 mm are adopted to investigate the flow regimes of air-water vertical upward two phase flow under adiabatic condition. The gas and liquid superficial velocities are 0 ≤ j_g ≤ 20m/s and 0.25 ≤ j_f ≤ 3m/s respectively which covering bubbly to annular flow. The flow regimes are identified by random forest algorithm and the flow regime maps are obtained. As the results, the transitional void fraction from slug to churn turbulent flow fluctuate from 0.47 to 0.58 which is significantly affected by the dimensional size of channel and flow rate. Besides, the void fraction at transitional points from churn-turbulent (slug) to annular flow are 0.66-0.67, which are independent with the gap size. Furthermore, a new criteria of slug to churn-turbulent flow is established in this study. In addition, by introducing the interfacial force model, the criteria of churn-turbulent (slug) flow to annular flow is verified.

• 한국산학기술학회논문지
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• 제17권7호
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• pp.420-424
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• 2016

본 연구에서는 지속적으로 심각한 대기오염의 문제로 실내 공기청정의 중요성이 대두되는 점을 감안하여 광촉매 단위기술을 개발하고자 건식 박막 공정 중 일반적으로 사용되어지는 RF 마그네트론 스퍼터링을 이용하여 $WO_3$ 단층막을 증착하였다. 초기 진공도는 $1.8{\times}10^{-6}$ [Torr]를 기준하여 최적의 스퍼터링 공정조건인 RF 100[W], 7[mTorr]진공 조건에서 Ar:$O_2$ 반응가스의 비율을 70[sccm] : 2[sccm]으로 하여 제작된 $WO_3$ 단층막은 380[nm]-780[nm]의 가시광 영역에서 80% 이상의 높고 일정한 광투과 특성을 확인하였다. 공기 청정 효과를 확인 위해 제작된 $WO_3$ 박막의 광촉매 특성을 조사하기 위해 메틸렌블루 내에서의 흡광도 및 농도변화를 광조사 시간 변화에 따라 측정하였다. 그 흡광도 측정결과 시간에 따라 흡광도 특성이 보임을 확인하였고, 5시간 경과 후 기존 메틸렌블루 농도 대비 80% 수준의 농도로 낮아지는 것을 확인하였다. 이런 결과로 부터 스퍼터링법에 의해 제작된 기능성 $WO_3$박막의 광분해 특성을 통해 형광등의 반사갓 혹은 LED등의 렌즈에 활용 된다면 차세대 조명원의 공기청정 효과를 증진시킬 수 있는 박막을 개발하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.431-432
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• 2012

In the era of 20 nm scaled semiconductor volume manufacturing, Microelectronics Manufacturing Engineering Education is presented in this paper. The purpose of microelectronic engineering education is to educate engineers to work in the semiconductor industry; it is therefore should be considered even before than technology development. Three Microelectronics Manufacturing Engineering related courses are introduced, and how undergraduate students acquired hands-on experience on Microelectronics fabrication and manufacturing. Conventionally employed wire bonding was recognized as not only an additional parasitic source in high-frequency mobile applications due to the increased inductance caused from the wiring loop, but also a huddle for minimizing IC packaging footprint. To alleviate the concerns, chip bumping technologies such as flip chip bumping and pillar bumping have been suggested as promising chip assembly methods to provide high-density interconnects and lower signal propagation delay [1,2]. Aluminum as metal interconnecting material over the decades in integrated circuits (ICs) manufacturing has been rapidly replaced with copper in majority IC products. A single copper metal layer with various test patterns of lines and vias and $400{\mu}m$ by $400{\mu}m$ interconnected pads are formed. Mask M1 allows metal interconnection patterns on 4" wafers with AZ1512 positive tone photoresist, and Cu/TiN/Ti layers are wet etched in two steps. We employed WPR, a thick patternable negative photoresist, manufactured by JSR Corp., which is specifically developed as dielectric material for multi- chip packaging (MCP) and package-on-package (PoP). Spin-coating at 1,000 rpm, i-line UV exposure, and 1 hour curing at $110^{\circ}C$ allows about $25{\mu}m$ thick passivation layer before performing wafer level soldering. Conventional Si3N4 passivation between Cu and WPR layer using plasma CVD can be an optional. To practice the board level flip chip assembly, individual students draw their own fan-outs of 40 rectangle pads using Eagle CAD, a free PCB artwork EDA. Individuals then transfer the test circuitry on a blank CCFL board followed by Cu etching and solder mask processes. Negative dry film resist (DFR), Accimage$^{(R)}$, manufactured by Kolon Industries, Inc., was used for solder resist for ball grid array (BGA). We demonstrated how Microelectronics Manufacturing Engineering education has been performed by presenting brief intermediate by-product from undergraduate and graduate students. Microelectronics Manufacturing Engineering, once again, is to educating engineers to actively work in the area of semiconductor manufacturing. Through one semester senior level hands-on laboratory course, participating students will have clearer understanding on microelectronics manufacturing and realized the importance of manufacturing yield in practice.

• 한국재료학회지
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• 제19권3호
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• pp.163-168
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• 2009

$Eu^{3+}$-doped $Y_2O_3$ red phosphor was synthesized in a flux method using the chemicals $Y_2O_3,\;Eu_2O_3,\;H_3BO_3$ and $BaCl_2{\cdot}2H_2O$. The effect of a flux addition on the preparation of $Y_2O_3:Eu_{3+}$ red phosphor used as a cold cathode fluorescence lamp was investigated. $H_3BO_3$ and $BaCl_2{\cdot}2H_2O$ fluxes were used due to their different melting points. The crystallinity, thermal properties, morphology, and emission characteristics were measured using XRD, TG-DTA, SEM, and a photo-excited spectrometer. Under UV excitation of 254 nm, $Eu_2O_3$ 3.7 mol% doped $Y_2O_3$ exhibited a strong narrow-band red emission, peaking at 612 nm. From this result, the phosphor synthesized by firing $Y_2O_3$ with 3.7 mol% of $Eu_2O_3$, 0.25 mol% of $H_3BO_3$ and 0.5 mol% of $BaCl_2{\cdot}2H_2O$ fluxes at $1400^{\circ}C$ for 2 hours had a larger particle size of $4{\mu}m$ on average compared to the phosphor of the $H_3BO_3$ flux alone. In addition, a phosphor synthesized by the two fluxes together had a rounder corner shape, which led to the maximum emission intensity.

• 한국진공학회지
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• 제19권1호
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• pp.36-44
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• 2010

관경이 수 mm인 세관 램프 내부에서 플라즈마의 확산을 조사하기 위하여 이극성(ambipolar) 확산방정식을 해하였다. 반경 방향의 확산에 의한 유리관 벽에서의 플라즈마 소멸 특성시간은 $\tau_r\;=\;(r_0/2.4)^2/D_a$로 주어진다. 반경 $r_0{\sim}1\;mm$이고 이극성 확산계수 $D_a{\sim}0.01\;m^2/s$ 이면, $\tau_r{\sim}17\;{\mu}s$이다. 이는 램프의 교류전원 구동에서 플라즈마를 유지하기 위한 구동 최소 주파수 ~30 kHz에 해당한다. 고전압이 인가되는 전극부에 발생한 고밀도의 플라즈마가 양광주로 확산되는 특성시간은 $\tau_z{\sim}0.1\;s$이다. 고밀도 플라즈마 경계에서의 시간에 대한 확산속도는 $t{\sim}10^{-6}\;s$일 때 $u_D{\sim}10^2\;m/s$이고, $t{\sim}10^{-3}\;s$이면 그 속도는 $u_D{\sim}1\;m/s$로 느려진다. 따라서 램프 길이 ~1 m에 대하여 전극부에서 생성된 고밀도 플라즈마가 양광주 전체로 확산되는 시간은 수 초가 걸린다.

• 한국진공학회지
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• 제17권4호
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• pp.331-340
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• 2008

교류 $50{\sim}100\;kHz$의 고주파와 수 kV의 고전압으로 구동되는 냉음극 형광램프의 전류 및 전압을 계측하는 방법을 조사하였다. 고 전압 측에 설치되는 프로브 자체의 임피던스 영향으로 램프의 휘도가 변화하고 누설 전류가 발생하여 정확한 전류 및 전압의 계측이 어렵다. 따라서 프로브의 임피던스와 누설 전류를 고려한 회로 분석을 통하여 올바른 계측 방법을 제시하였다. 프로브 설치로 휘도 변화 시, 인버터에 입력되는 DC 전압을 조정하여 램프의 특정 휘도를 유지하여 계측한다. 램프 전류($I_G$)는 접지 측에서 전류 프로브나 고주파 전류계로 계측하며, 전압은 고 전압 측에 설치한 전압 프로브로 계측한다. 램프 전압($V_C$)은 고전압이 인가되는 냉음극과 안전 캐패시터 사이에서 계측하며, 인버터의 출력 전압(VI)은 안전 캐패시터와 인버터 출력단 사이에서 계측한다. 램프 전압($V_C$)과 램프 전류($I_G$)의 위상차가 없기 때문에, 램프 자체의 순수 소모 전력은 램프 전압($V_C$)와 램프 전류($I_G$)의 곱이다. 인버터의 출력 전압($V_I$)과 램프 전류($I_G$)의 위상차($\theta$)는 전압 프로브의 용량성 임피던스로 인하여 계측값이 부정확하며, 회로의 분석에서 얻어진 $cos{\theta}=V_C/V_I$로부터 위상차를 얻을 수 있다.