• 한국전기전자재료학회논문지
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• 제26권10호
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• pp.745-753
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• 2013

Performance of organic light-emitting diodes incorporating microlens array was simulated using a Light Tools software. Use of microlens array can help the light to escape out of the device. We simulated a reference device that is consisted of reflection layer, emissive layer, and flat transparent substrate. And in this reference device, outcoupled efficiency of 22% was obtained. Several shapes of microlens were applied such as hemisphere, trapezoid, cone, and rectangular parallelepiped. The results showed the improvement of outcoupled efficiency of the device with microlens compared to that of the reference one. And from the analyses of the simulated data, the obtained appropriate shape of microlens is hemisphere, and the improvement of the device with hemispherical lens is 57% higher than that of the reference one.

• 한국수산과학회지
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• 제12권2호
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• pp.79-86
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• 1979

빛이 어류의 행동에 미치는 영향을 조사하기 위하여 잉어, Cyprinus carpio에 광척극을 가한 실험을 낮과 밤에 각각 실시한 결과를 요약하면 다음과 같다. 1. 잉어의 분포율은 본 실험에 사용한 제한된 수조내에서 U자형과 거의 같은 구간분포경향을 보였다. 2. 빛의 세기가 어떤 적정치보다 더 강하거나 약할 때 어류가 광원으로부터 멀리 떨어진 곳에 모였기 때문에 잉어의 적정수중조도가 발견되었다. 3. 수중조도에 대한 집어율곡선의 최대치로부터 잉어의 집어율이 낮과 밤에 차이가 있었다. 4. 잉어의 집어율이 최대인 평균수중조도는 낮에 $3.813lux(2.99\~4.761\;lux)$였고, 밤에는 $6.292lux(5.0\~7.89\;lux)$였다. 5. 잉어의 집어율은 반사집어율과 평형집어율의 두가지 형태로 나타났다. 6. 반사집어율은 광원을 점등한 직후에 나타났으며, 시간에 따라 변화를 보였고, 평형집어율은 거의 균일하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.314.2-314.2
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• 2014

To improve the optical and electrical properties of commercialized GaN-based light-emitting diodes (LEDs), many methods are suggested. In recent years, great efforts have been made to improve the internal quantum efficiency and light extraction efficiency (LEE) and promising approaches are suggested using a patterned sapphire substrate (PSS), V-pit embedded LED structures, and silica nanostructures. In this study, we report on the enhancement of photoluminescence (PL) intensity in GaN-based LED structures by using the combination of SiO2 (silica) nanospheres and polystyrene/SiO2 core-shell nanospheres. The SiO2 nanospheres-coated LED structure shows the slightly increased PL intensity. Moreover the polystyrene/SiO2 core-shell nanospheres-coated structure shows the more increase of PL intensity comparing to that of only SiO2 spheres-coated structure and the conventional structure without coating of nanospheres. The Finite-difference time-domain (FDTD) simulation results show corresponding result with experimentally observed results. The mechanism of enhancement of PL intensity using the coating of polystyrene/SiO2 core-shell nanospheres on LED surface can be explained by the improvement in extraction efficiency by both increasing the probability of light escape by reducing Fresnel reflection and by multiple scattering within the core-shell nanospheres.

• 한국안전학회지
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• 제29권6호
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• pp.15-21
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• 2014

Many kinds of falling prevention systems with a safety block have been supplied in order to prevent falling accidents and acquire the long life and cost down for the maintenance. However, there are not the reliable and domestic the falling prevention system until now. Almost systems were imported from U.S.A, Japan, U.K and Germany. The structural safety of the imported safety block is satisfied sufficiently, but it has heavy weight due to the cover with the aluminum and thickness. Especially, the falling prevention system as the safety block is very expensive. It brings about flow the enormous money out of country. Furthermore it has a heavy weight when workers climbed the ladder with a falling prevention system and moved, many workers are not feeling themselves. Thus, the aim of this work is to develop a commercial self-escape SRL(Self Retracting Lifeline) with the safety block function that has a light weight and an advanced strength. The cost efficiency and convenience of the system and safety for workers also will be improved remarkably even though this system has a light weight. The results show that the maximum stress is obtained in each part by the lower more than yield strength and has sufficient safety in the developed new safety block.

• 인문언어
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• 제1권2호
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• pp.161-178
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• 2001

This study investigates how Korean traditional family consciousness interacts with Korean industrialization in the 1970s. In Our Children, Lee Sun depicts a family's struggle within the turmoil brought about by rapid industrialization to escape from the ranks of the working class. It is well known that one of the consequences of industrialization was the breakup of the larger family structure into nuclear families, but Lee Sun presents Korea's industrialization in the 1970s in the light of the traditional Korean family culture before the breakup. In other words, he gives us a portrayal of Gemeinschaft in Gesellschaft in his description of the extended family's struggle to overcome the day-to-day pressures of modernization and urbanization. The novel presents three generations of a traditional extended family. The eldest son is portrayed as a knife, strong and sharp. His wife has a temporary job that she hopes to give up once they own a house, which symbolizes the family's escape from the working class. The relationship among the family members reveals the core aspects of the ideology governing traditional extended families: the husband is the despotic monarch of the household, solely responsible for the family's economy; the husband is the sky and the wife the earth; and children (the more the better) are expected to lead to stability, welfare, and prosperity. One curious aspect of this family relationship as portrayed by Lee Sun is the expectation that being the eldest son, who already is or will become the patriarch of the family, is the fastest way of reaching middle-class status. And, despite a slight reversal, the novel has a happy ending wherein the family's expectations are fulfilled without much suffering. This aspect should be considered in light of the revolutionary romantic idealism of the novels of the 1930s. The lack of suffering and the easy happy ending may be attributed to the fact that Korea's industrialization came about rapidly and radically, and therefore it is likely that Lee Sun was not able fully to appreciate the full costs of industrialization. This limitation calls for a deeper investigation into the social structure and class consciousness of the 1970s, and also a study of the intertextual relationship of Our Children with other novels of the time.

• Journal of the Optical Society of Korea
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• 제2권1호
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• pp.13-21
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• 1998

Based on the escape cone concepts, high-brightness light-emitting diodes (LEDs) have been analyzed. In AlGaAs or InGaAlP LEDs, photon absorption in the ohmic region under the electrode is known to be significant. Thus, ins general, a thick window layer (WL) and a transparent substrate (TS) would minimize photon shielding by the electrodes and considerably improve photon output coupling efficiency. However, the schemes do not seem to be necessary in InGaN system. Photon absorption in ohmic contact to a wide bandgap semiconductor such as GaN may be negligible and, as a result, the significant photon shielding by the electrodes will not degrade the photon output coupling efficiency so much. The photon output coupling efficiency estimated in InGaN LEDs is about 2.5 - 2.8 times that of the conventional high-brightness LED structures based on both WL and TS schemes. As a result, the extenal quantum efficiency in InGaN LEDs is as high as 9% despite the presumably very low internal quantum efficiency.

• 한국융합학회논문지
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• 제11권1호
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• pp.301-308
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• 2020

본 연구는 다중이용시설의 화재대피 상황에 대한 분석을 바탕으로 다중이용시설에 적합한 피난유도등 디자인을 제안하고자 하였다. 화재는 재난으로 임의묘사가 불가하여 다중이용시설의 대피상황을 이해하기 위한 동영상 분석을 진행하였다. 동영상 분석을 통해 다중이용시설 화재의 대피상황에서 기존 피난유도등의 문제점과 필요한 니즈를 파악할 수 있었고 이를 피난유도등 디자인에 반영하였다. 피난유도등 디자인 결과, 벽부형 유도등은 LED 배치구조를 달리하여 제품의 두께를 최소화 하였다. 천정형 유도등은 복잡한 구조의 복도에 추가적으로 설치할 수 있도록 형태를 보완하였다. 본 연구의 결과는 실제 피난유도등 제작에 사용되는 기준들을 바탕으로 디자인한 결과로 향후 실험측정과 전문가 자문을 통한 보완단계를 거쳐 실용화 방안을 모색하고자 한다.

• 천문학논총
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• 제23권2호
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• pp.31-35
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• 2008

We present analytical approximations for calculating the scattering and escape of non-ionizing photons from a plane-parallel medium with uniformly illuminated by external sources. We compare the results with the case of a spherical dust cloud. It is found that more scattering and absorption occur in the plane-parallel geometry than in the spherical geometry when the optical depth perpendicular to the plane and the radial optical depth of the sphere are the same. The results can provide an approximate way to estimate radiative transfer in a variety interstellar conditions and can be applied to the dust-scattered diffuse Galactic light.

• 한국정밀공학회지
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• 제21권12호
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• pp.21-28
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• 2004

In modem manufacturing industries such as the airplane and automobile, aluminum alloys which are remarkable in durability have been utilized effectively. High-speed machining technology for surface roughness quality of workpiece has been applied in these fields. Higher cutting speed and feedrates lead to a reduction of machining time and increase of surface quality. Furthermore, the reduction of time required for polishing or lapping of machined surfaces improves the production rate. Traditional milling process for high speed cutting can be machined with end mill tool. However, such processes are generally cost-expensive and have low material removal rate. Thus, in this paper, face milling cutter which gives high MRR has developed face milling cutter body for the high speed machining of light alloy to overcome the problems. Also vibration experiment to detect natural frequency in free state and frequency characteristics during machining are performed to escape resonance.

• 한국생산제조학회지
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• 제21권5호
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• pp.814-823
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• 2012

Fluctuation of light intensity from the keyhole becomes more significant in full penetration welding than partial penetration welding, since the plasma produced in the keyhole can escape from the rear side of the keyhole. The plasma optical radiation emitted during Nd:YAG laser welding of S45C steel samples has been detected with a Photodiode and analyzed under different process conditions. As the results, the BOP was performed for welding, behavior of plasma, spatter or plume was monitored to determine the reference signal. Then, random combination was made for comparison with the reference signal, which aimed at verifying reliability of the welding monitoring system that this study intended to develop.