• 한국가시화정보학회지
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• 제10권3호
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• pp.21-24
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• 2012

Although the motion of the three-phase contact line on a solid substrate has been extensively studied thus far, the understanding of the dynamics of the contact line of liquid/liquid/gas phases is far from complete. Here we deposit a drop of isopropyl alcohol (IPA) on water and HFE-7100 whose free surfaces are exposed to air to observe the flow field around the contact line. By combining the shadowgraph and high-speed imaging techniques, we find that vortices are spontaneously generated at the contact line, which grow in size with time. The flow is attributed to the Marangoni stress that pulls a liquid of lower-surface tension toward a liquid surface having a higher surface tension. However, it is not still clear why the entrained lower-surface-tension liquid should whirl rapidly beneath the contact line. We also visualize the flow by the particle image velocimetry (PIV) to find out that the rotational velocity reaches the order of 1 mm/s near the free surface.

• Journal of Applied Biological Chemistry
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• 제56권3호
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• pp.137-139
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• 2013

강황(Curcuma longa)으로부터 bisdemethoxycurcumin (BDMC), demethoxycurcumin (DMC) 및 curcumin의 생물 활성을 offline-ABTS 측정법과 on-line screening high-performance liquid chromatography (HPLC)-ABTS 측정법을 적용한 빠른 스크리닝을 통해 정량 및 성분 분리를 하였다. 이때, off-line-ABTS와 on-line screening HPLC-ABTS 비교는 미미한 오차를 보여주었다.

• 한국전기전자재료학회논문지
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• 제16권4호
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• pp.322-329
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• 2003

We have studied how surface pretilt angle affects generation of disclination line in liquid-crystal-on silicon cells for 45$^{\circ}$-twisted nematic (TN) and vertical alignment (VA) modes with pixel size of 15$\mu\textrm{m}$. Our studies show that when the pretilt angle is increased from 0$^{\circ}$to 3$^{\circ}$ in the 45$^{\circ}$-TN cell, the disclination line at left side of on-pixel becomes weak and is well suppressed with $\theta$$\_$p/=3$^{\circ}$ although the pixel size Is decreased. In the VA cell, when the pretilt angle is decreased from 89$^{\circ}$ to 86$^{\circ}$, the disclination line at right side of the on-pixel is suppressed well and even for a smaller pixel size, it does not exist when $\theta$$\_$p/=86$^{\circ}$. The results inform that the pretilt angle strongly affects the image quality of microdisplays.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.1112-1114
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• 2017

액체 로켓 엔진은 채택되는 사이클, 하드웨어 구성, 기능 구현상의 짐벌 타입 등에 의해 구성품 배치와 레이아웃의 라우팅이 결정된다. 본 논문에서는 액체로켓엔진에 장착되는 주요 구성품을 기준으로 구동을 담당하는 헬륨(He) 공급 공압라인, 각종 퍼지 공압라인, 주 점화라인 등의 주요 유공압 라인의 개념 라우팅을 수행하였다.

• Korean Chemical Engineering Research
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• 제43권2호
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• pp.259-265
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• 2005

Water+n-methylformamide(NMF), benzene+NMF 그리고 toluene+NMF의 353.15 K 이성분계 등온 기-액상평형을 headspace gas chromatography(HSGC)로 측정하였고, NMF+benzene+n-heptane과 NMF+toluene+n-heptane 삼성분계에 대한 298.15 K 액-액상평형을 tie-line 측정법으로 결정하였다. 이성분계 기-액상평형 데이터는 공비점이 없었으며, $g^E$ 모델식(Margules, van Laar, Wilson, NRTL, UNIQUAC)에 비교적 작은 편차로 잘 상관되었다. 삼성분계 tie-line 데이터는 NRTL식과 UNIQUAC식을 이용하여 상관과 추산을 병행하였으며, Hirata-Fujita식과 Maior-Swenson식을 이용하여 정확도를 검증하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.34-37
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• 2007

액체산소를 작동유체로 하여 추진제 공급배관에 대한 충진 및 대기 시험을 수행하였다. 추진제 공급 시스템은 추진제 탱크의 출구에 필터가 장착된 형상이다. 추진제의 충진이 완료된 후 대기 과정동안 액체산소의 증발과 이것이 시스템의 재순환 성능에 미치는 영향을 살펴보았다. 추진제의 충진 속도와 탱크 얼리지의 압력이 배관 내 액체산소의 상태에 영향을 미치는 것을 확인하였다. 필터의 장착 위치로 인해 대기 과정동안 배관 내부에서 geysering 현상은 발생하지 않았다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1255-1260
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• 2008

This study is simulation of high elevated liquid line of a modular heat pump system to observe longitudinal subcooling variation. In a high elevated tube, subcooled refrigerant(R410A) through a condenser changes its states by heat transfer with surrounding air and by pressure drop from elevation. In this study, the liquid line was simulated through correlations of heat transfer and pressure drop for the variation from single-phase into two-phase flow. Pressure drop, heat transfer rate and vapor quality were calculated as key parameters. Two-phase turning heights and variations of the key parameters were confirmed from the simulation. As a result, high elevation of liquid line has great influence on upward flow, which requires additional equipment to compensate the variation.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.68-73
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• 2011

This study was performed numerical analysis in order to analyze liquid film flow of heat exchanger tube arrangement and configuration of evaporative multi effect distillation system using medium-temperature. Simulation was accomplished the two-dimensional calculations using commercial analyses program FLUENT based on the FVM(finite volume method). Fresh water generator of this study used Shell & Tubes heat exchanger with Cu_Ni tube, configuration of tube used bare tube and corrugated tube, and arrangement of tube used in-line array and staggered array. Performance of heat exchanger through the formation of liquid film was compared and analyzed. Liquid film flow occurred that falling on heat exchanger tube wall. Result of simulation showed that liquid film thickness of in-line arrangement was found 0.57mm with bare tube and 0.67mm with corrugated tube, respectively. And liquid film thickness of staggered arrangement was found 0.39mm with bare tubes and 0.62mm with corrugated tubes, respectively. Liquid film thickness of corrugated tube showed thicker than bare tube, but heat transfer rates of corrugated tube showed higher than bare tube. The reason was considered that surface area of corrugated tube was wider than bare tube. And liquid film thickness of staggered arrangement showed thinner than in-line arrangement, so thermal performance of staggered arrangement showed higher than in-line arrangement.

• 한국전기전자재료학회논문지
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• 제17권6호
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• pp.622-632
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• 2004

We have studied how liquid crystal's rubbing direction and voltage driving method affect generation of disclination line. At first, generation of disclination line in vertical alignment(VA) cell and VA-twisted nematic(TN) cell has been examined. When liquid crystal's rubbing direction of bottom substrate was 0$^{\circ}$, the degree of generated disclination line was the smallest value. Further, the generation of disclination line above the electrode is less in the frame inversion than in the line inversion. Secondly, we have examined a generation of disclination line in reflective fringe-field switching cell. When the distance between common electrodes is over 3 ${\mu}{\textrm}{m}$ with on-state of one pixel and off-state of neighboring pixels, the reflectance appears only on-state pixel without generating reflectance in adjacent pixels.

• Journal of Astronomy and Space Sciences
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• 제26권4호
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• pp.693-702
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• 2009

액체로켓엔진의 구성품 중 하나인 산화제 라인 시스템의 3차원 모델과 유동해석을 수행하였다. 전체 시스템의 유동해석에 앞서 각 구성품들의 개별적인 유동해석과 단순화된 모델을 통해 최적의 위치를 결정하였다. 그 결과 가스발생기 라인의 입구는 압력보상이 필요하며 오리피스의 위치에 따라 출구 유동의 형태가 달라지는 것을 확인할 수 있었다. 전체적으로 해석된 라인 시스템은 주어진 요구조건을 만족하는 것으로 나타났으며 이는 실제 제품 제작과 시험을 통해 확인할 예정이다.