• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.10
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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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.2
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• pp.79-86
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• 1979

The phototaxis of common carp Cyprinus carpio was studied tinder laboratory conditions to find out distributional pattern of the fish under light gradient and to find the light intensity which causes the maximum gathering rate. The optimum light intensities were determined, The fish tended to escape from tile light source when the light intensity was stronger or weaker than a certain optimum value. The mean illumination intensity which caused the maximum gathering rate was 3.813lux (2.99-4.76 lux) in the daytime and 6.292 lux (5.0-7.89 lux) at night. The gathering rate of the fish could be divided into two types: reflex gathering rate and equilibrium gathering rate. The reflex gathering rate appeared quickly soon after lighting and gradually changed as time elapsed, while the equilibrium gathering rate was almost always constant.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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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.

• Journal of the Korean Society of Safety
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• v.29 no.6
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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.

• Lingua Humanitatis
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• v.1 no.2
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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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• v.2 no.1
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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.

• Journal of the Korea Convergence Society
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• v.11 no.1
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• pp.301-308
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• 2020

Based on the analysis of fire escape situations in public facility, this study was intended to propose a design of emergency light suitable for fire in public facility. A video analysis was conducted to understand the evacuation situation of public facility because the fire could not be randomized due to the disaster. Through video analysis, we were able to identify inconvenience and necessary needs in avoiding fire in public facility and reflected them in the design of emergency light, etc. As a result of the design of emergency light, the wall type induction lamp had different LED layout structures to minimize the thickness of the product. Ceiling induction lamps have been supplemented for additional installation in corridors of complex structures. The results of this study are designed based on the criteria used in the manufacture of actual emergency light and we intend to explore ways to be practical through further experiment measurements and complementary steps through expert advice.

• Publications of The Korean Astronomical Society
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• v.23 no.2
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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.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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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.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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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.