• 한국전기전자재료학회논문지
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• 제32권2호
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• pp.141-146
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• 2019

Non-emissive LCDs need a backlight, and have difficulty implementing wide viewing angles due to differences in phase retardation depending on the behavior of the liquid crystals. Although wide viewing angles are good characteristics for devices such as TVs, they are not good for mobile devices. In this paper, we propose ways to design diffusers with ELC lenses to achieve wide and narrow viewing angles depending on the circumstances. A study was conducted on optimizing the design of a liquid lens diffuser with the same light as that for an OLED, by extracting design factors that affect the performance of the diffuser and applying the Taguchi method to them.

• 대한지하수환경학회지
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• 제2권1호
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• pp.22-29
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• 1995

유동 세균 입자는 지체계수를 감소시키므로써 지하수에서 소수성 오염물의 이동을 촉진시킨다. 그 크기와 표면의 적당한 물리화학적 조건으로 인하여 세균은 효율적인 오염물의 운반자가 될 수 있다. 이러한 운반자가 있을 때, 그 계는 액상, 입상, 그리고 고상의 3 상으로 해석되어야한다. 오염물은 각 상에 모두, 혹은 그 중의 일부에 존재할 수 도 있다. 본 연구에서는 세균이 있는 경우, 생화학적으로 분해 가능한 유기성 오염물의 다공매질에서의 거동을 물질수지에 기초하여 수학적 모델로 묘사한다. 세균의 액상과 고상사이의 물질 전이 및 오염물의 액상과 입상사이의 물질 전이는 동역학적 관계식으로 나타냈다. 모델 결과를 일반화하기 위하여 무차원화를 수행했고, 그 해를 구하여 세균에 의한 오염물의 가속이송 효과를 알 수 있었다. 모델 결과는 문헌상의 실험결과와 비교되었다. 모델 결과로부터 오염물은 그 계의 Damkohler I 수가 10 이상일 경우 국지 평형 가정을 할 수 있었으며, 세균의 성장율과 주입 농도 등이 오염물의 청소에 아주 중요한 요소임을 알 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1996년도 춘계 학술대회논문집
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• pp.58-67
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• 1996

This paper describes some computational results of various energy and environmental systems using Patankar's SIMPLE method. The specific topics handled in this study are jet bubbling reactor for flue gas desulfurization, cyclone-type afterburner for incineration, 200m tall stack for 500 MW electric power generation, double skin and heat storage systems of building energy saving for the utilization of solar heating, finally turbulent combustion systems with liquid droplet or pulverized coal particle. A control-volume based finite-difference method with the power-law scheme is employed for discretization. The pressure-velocity coupling is resolved by the use of the revised version of SIMPLE, that is, SIMPLEC. Reynolds stresses are closed using the standard $k-{\varepsilon}$ and RNG $k-{\varepsilon}$ models. Two-phase turbulent combustion of liquid drop or pulverized coal particle is modeled using locally-homogeneous, gas-phase, eddy breakup model. However simple approximate models are incorporated for the modeling of the second phase slip and retardation of ignition without consideration of any detailed particle behavior. Some important results are presented and discussed in a brief note. Especially, in order to make uniform exit flow for the jet bubbling reactor, a well-designed structure of distributor is needed. Further, the aspect ratio in the double skin system appears to be one of important factors to give rise to the visible change of the induced air flow rate. The computational tool employed in this study, in general, appears as a viable method for the design of various engineering system of interest.

• 한국동물위생학회지
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• 제30권3호
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• pp.291-304
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• 2007

Mutants of an obligate aerobic bacterium, Vitreoscilla, that have deficiency in heat-labile catalase-peroxidase hydroperoxidase I (HPI) were created by EMS treatment. The catalase-peroxidase HPI-deficient mutant showed substantially lower peroxidase activity in exponential and mid-stationary phase compared with the wild type strain. In late stationary phase, the mutant exhibited no peroxidase activity. Peroxidase deficiency in the mutant was revealed by polyacrylamide gels stained for peroxidase activity. Characteristically, catalase levels in the mutant increased about 14- and 8-fold during growth in the exponential and stationary phases, respectively, compared to those in the wild type, suggesting a compensatory effect for protection from $H_2O_2$ toxicity. The mutant showed differences in physiology from the wild type: retardation in growth rate and decrease in oxygen consumption. Both the wild type and the catalase-peroxidase HPI-deficient mutant of Vitreoscilla had lower growth rates in media containing increasing $H_2O_2$ concentrations. However, the mutant exhibited an additionally decreased growth rate after 6 to 8 h of growth compared to the wild type. The wild type was resistent up to 20 mM $H_2O_2$, whereas the mutant was very sensitive to high concentrations of exogenous $H_2O_2$. Although elevated catalase levels would provide protection of the bacteria from the deleterious effect of $H_2O_2$, it did not appear to be complete. Cell-free extracts of the mutant showed decreased NADH oxidation rates and higher accumulation of $H_2O_2$ during this oxidation. These results may account for the impaired growth and earlier onset of death phase by the catalase-peroxidase HPI-deficient mutant of Vitreoscilla.

• 한국광학회지
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• 제11권6호
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• pp.385-389
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• 2000

본 논문에서는 원형 대칭 광 시스템에 대한 초점 심도를 증가시키기 위해 Wigner 분포 함수(WDF)로 유도된 위상 지연 함수를 이용한다. 1차원 신호에 대한 WDF는 위상-공간($\chi,\zeta$)상의 2차원 함수로 표현되고 Strehl 비 (SR)를 이용해 정규화된 복사조도로 나타낸다. 초점 심도의 증가는 WDF 공간상에서 간단한 조작으로 자유공간 전파의 특성을 나타내는 전단 기울기 $\alpha$을 부여함으로서 달성된다. 또한 $\alpha$을 초점 심도의 항 $\delta_z$로 표현함으로서 위상 지연 함수를 통해 정량적으로 초점특성을 평가할 수 있는 방법을 제안한다. 제안된 방법으로 수치 해석한 결과를 다른 접근법으로 수행되었던 연구결과와 비교한다.

• 한국안광학회지
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• 제6권2호
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• pp.11-16
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• 2001

렌즈에 가한 응력을 측정하기 위한 편광기는 1/4 파장판-편광판으로 구성하였고, 각 단계별 광파의 $E_1$, $E_2$의 성분을 분석하였다. 주 응력차 ${\sigma}_1-{\sigma}_2$는 무늬 차수(N)가 시료 각 점에서 분석되고, 시료의 광축은 주 응력 방향과 일치하는 것으로부터 2 차원 모델을 결정할 수 있다. 광파에 작용하는 복굴절성과 위상지연은 주 응력차 (${\sigma}_1-{\sigma}_2$)에 비례하고, 최종 광파의 세기는 $sin^2({\Delta}/2)$에 비례하고, ${\Delta}/2=n^{\pi}$ (n=0, 1, 2, ...)일 때 소멸 무늬인 흡광이 일어난다. 실험적 결과로는 렌즈의 외부 응력의 크기에 따라 흡광 band가 이동한다.

• 소성∙가공
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• 제8권3호
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• pp.309-309
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• 1999

Effects of rare earth metals addition and aging treatment on corrosion resistance and mechanical properties of super duplex stainless steels were investigated using optical/SEM/TEM metallographic examination, an X-ray diffraction test, a potentiodynamic anodic polarization test and a tensile test. The performance of the experimental alloy with 0.32% REM addition was compared with commercial super duplex stainless steel such as SAF 2507 when they were exposed to solution annealing heat treatment and aging treatment. The corrosion resistance in CF environments and mechanical properties of the experimental alloy were found superior to those of the commercial duplex stainless steel. The REM with larger atomic radii than those of Cr, Mo and W may fill vacancies inside the matrix and around the grain boundaries, retarding formation of harmful intermetallic σ and χ phases. In addition, fine REM oxides/oxy-sulfides (1-3㎛) seemed to enhance the retardation effects. With REM additions, strength and ductility increased due to the phase and grain refinement caused by fine REM oxides and oxy-sulfides.

• 한국전기전자재료학회논문지
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• 제29권8호
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• pp.494-498
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• 2016

In this paper, we proposed the 3-dimenstional (3D) analysis for calculating the optical characteristics of an autostereoscopic display with electric field driven liquid crystal (ELC) lens. From 3D analysis considering the slanting of lens, we calculate the cross-talk of each images and the distortion of viewing zone. Using geometric opics and extended Jones matrix method (EJMM), phase retardation of ELC lens according to position is calcuated and then optical path difference in 3D space considering tilt and azimuth angle of incident light is gotten. Then, intensity distribution is presented in the space. Through camparing the intensity distribution using ideal lens with the ELC lens, we identify the noise and image distortion of ELC lens. As a result, this analysis is expected to provide optimum design conditions for realistic and rigorous 3D display with ELC lens.

• 한국재료학회지
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• 제15권12호
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• pp.802-808
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• 2005

The hydrogen sorption speeds of $Zr_{57}V_{36}Fe_7$ amorphous alloy and its crystallized alloys were evaluated at room temperature $Zr_{57}V_{36}Fe_7$ amorphous alloy was prepared by ball milling. The amorphous alloy was crystallized through two stages. Initially, $\alpha-Zr$ solid solution was appeared from the amorphous phase. Two cubic Laves compounds were precipitated afterwards from the remained amorphous and from excessively saturated solid solution at higher temperature. The hydrogen sorption speed of the partially crystallized alloy was higher than that of amorphous. The enhanced sorption speed of partially crystallized alloy was explained in terms of surface oxygen stability which has been known to retard the activation of amorphous alloys. The retardation could be reduce by crystallization process resulting in the observed increase in sorption property.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.100-103
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• 2005

Homogeneously aligned nematic liquid crystal modes are representatively the -FFS (fringe-field switching) mode using liquid crystal (-LC) with negative dielectric anisotropy, the +FFS mode and the IPS (in-plane switching) mode using +LC with positive dielectric anisotropy. In view of image quality evaluation standard of LCD, we compared characteristics of the brightness, the contrast ratio (CR) and color shift when the modes have respectively optimized phase retardation values $(d{\Delta}n)$. Consequently, in the most sensitively viewing angle of a man's physical vision, both FFS modes have advantage over the IPS mode from the brightness & the CR point of view. We are also confirmed that the +FFS mode out of them shows the smallest color shift according to all viewing directions in grey levels.