• 전기학회논문지
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• 제63권10호
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• pp.1377-1383
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• 2014

This paper deals with eddy current loss of magnetic coupling with radial permanent magnet (PM) using analytical method such as a space harmonic method. Superposition of two kinds analysis model is used to analyze eddy current loss induced in inner PM and outer PM of magnetic coupling. When the eddy current is induced, the environmental temperature increases, and the permanent magnet(PM) characteristics are degraded because the performance of PM is greatly influenced by temperature rise. Hence, the calculation of eddy current loss becomes an important factor in the magnetic coupling. In order to analyze eddy current loss, first, on the basis of the magnetic vector potential and two-dimensional(2-D) polar-coordinate system, the magnetic field solutions of the radial magnetized PM are obtained. And we obtain the analytical solutions for the eddy current density produced by permanent magnet. Lastly, analytical solutions for eddy current loss are derived by using equivalent, electrical resistance calculated from magnet volume and analytical solution for eddy current density. This analytical results are validated by comparing with the 2-D finite element analysis (FEA).

• 조명전기설비학회논문지
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• 제23권6호
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• pp.78-84
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• 2009

본 논문은 토양의 방전 영역에서 소규모 접지전극의 과도접지임피던스의 측정결과를 제시한다. 접지전극 주변에서 이온화 특성을 사실적으르 분석하기 위해서 세 가지 형상의 접지전극을 실외에 설치하고, 고전압 임펄스 발생기를 사용하여 시험전류를 인가하였다. 정지전극에서 대지로 흐르는 전류와 응답 전압을 분석한 결과, 접지전극 주변의 이온화는 높은 대지저항률률의 토양에서 접지임피던스 감소에 기여하며 대지전위상승을 효과적으로 제한하는 것이 확인된다. 하지만 낮은 대지저항률의 토양에서는 이온화 임계전계강도가 작아서 전극 형상이 과도접지임피던스에 거의 영향을 주지 못한다. 그리고 전극형상에 따른 실험결과, 판전극보다 침부봉전극이 이온화 영역 전압범위 내에서 과도접지임피던스 저감에 보다 효과적이다.

• 한국수자원학회논문집
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• 제30권5호
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• pp.459-465
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• 1997

스팀의 온도와 압력을 이용하여 불수용성 유기화합물(NAPL)로 오염된 토양의 정화가능성을 알아보기 위한 실험을 수행하였다. Octane, Toluene, Xulene과 같은 단일 NAPL인 Gasoline을 대상으로 실험을 수행하였으며, 사용된 토양은 주문진 표준사와 국내 지반에 많인 산재하는 화강토를 선택하였다. 실험결과 1 pore volume의 스팀주입으로 인한 NAPL제거율은 모래의 경우 66∼78%, 화강토의 경우는 45∼73%로 나타나 상대적으로 짧은 시간에 부작용 없이 오염물을 토양으로부터 제거할 수 있는 가능성을 보였다. 배경온도가 높을수록 스팀의 응축이 지연되고 NAPL의 유동성이 중가하여 제거율이 높아짐을 확인하였다. 또한, 스팀주입 후 온수를 유입시켜 간극사이에 증기 및 액체상태로 존재하는 NAPL을 추가로 추출할 수 있었으며, 유입수의 온도에 따라 제거율이 최고 750%까지 상승함을 알 수 있었다.

• Journal of Welding and Joining
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• 제1권2호
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• pp.45-52
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• 1983

Many pressure vessels for the hot H$\sub$2//H$\sub$2/S service are made of 2+1/4Cr-1Mo steel with austenitic stainless steel overlay to combat agressive corrosion due to hydrogen sulfide. Hydrogen dissolves in to materials during operation, and sometimes gives rise to unfore-seeable damages. Appropriate precautions must, therefore, be taken to avoid the hydrogen induced damages in the design, fabrication and operation stage of such reactor vessels. Recently, hydrogeninduced cracking (or Disbonding) was found at the interface between base metal and stainless weld overlay of a desulfurizing reactor. Since the stainless steel overlay weld metal is subjected to thermal and internal-pressure loads in reactor operation, it is desirable for the overlay weld metal to have high strength and ductility from the stand point of structural safety. In section III of ASME Boiler and Pressure Vessel Code, Post-Weld Heat Treatment(PWHT) of more than one hour per inch at over 1100.deg. F(593.deg. C) is required for the weld joints of low alloy pressure vessel steels. This heat treatment to relieve stresses in the welded joint during construction of the pressure vessel is considered to cause sensitization of the overlay weld metal. The present study was carried out to make clear the diffusion of carbon migration by PWHT in dissimilar metal welded joint. The main conclusion reached from this study are as follows: 1) The theoretical analysis for diffusion of carbon in stainless steel overlay weld metal does not agree with Fick's 2nd law but the general law of molecular diffusion phenomenon by thermodynamic chemical potential. 2) In the stainless steel overlay welded joint, the PWHT at 720.deg. C for 10 hours causes a diffusion of carbon atoms from ferritic steel into austenitic steel according to the theoretical analysis for carbon migration and its experiment. 3) In case of PWHT at 720.deg. C for 10 hours, the micro-hardness of stainless steel weld metal in bonded zone increase very highly in the carburized layer with remarkable hardening than that of weld metal.

• Molecules and Cells
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• 제37권1호
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• pp.31-35
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• 2014

Induced pluripotent stem cells (iPSCs) are capable of unlimited self-renewal and can give rise to all three germ layers, thereby providing a new platform with which to study mammalian development and epigenetic reprogramming. However, iPSC generation may result in subtle epigenetic variations, such as the aberrant methylation of the Dlk1-Dio3 locus, among the clones, and this heterogeneity constitutes a major drawback to harnessing the full potential of iPSCs. Vitamin C has recently emerged as a safeguard to ensure the normal imprinting of the Dlk1-Dio3 locus during reprogramming. Here, we show that vitamin C exerts its effect in a manner that is independent of the reprogramming kinetics. Moreover, we demonstrate that reprogramming cells under 2i conditions leads to the early upregulation of Prdm14, which in turn results in a highly homogeneous population of authentic pluripotent colonies and prevents the abnormal silencing of the Dlk1-Dio3 locus.

• 한국초지조사료학회지
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• 제10권2호
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• pp.115-120
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• 1990

A series of experiments were carried out for two successive years to investigate the productivity of forage turnip in mid-northern area of Korea. Fresh matter and dry matter yields of 6 foreign cultivars (Purple Top Strap Leaved, Purple Top White Globed, Seven Top, Shogoin, White Egg and Amber Globe) seeded either in early spring or in autumn after harvesting forage corn were evaluated with different seeding date and harvesting date as well as with different level of fertilization. The results obtained are summarized as follows: 1. The earlier the seeding date in spring (Mar. 29, Apr. 12, Apr. 16) was, the higher was the yield of fresh matter and dry matter as the plant growth ceased after mid June, when the temperature began to rise. 2. In spite of its high DM yield, the Japanese cultivar, Shogoin, showed poor forage quality for summer feeding due to its earlier bolting in harvesting season. 3. Of the 6 cultivars Purple Top White Globed showed highest DM yield (800 kg/ 10a) in mid area including SEOUL irrespective of planting season. 4. Although the turnips showed mostly positive yield responses to fertization, the differences were not great especially above the level of$N-P_2O_5-K_2O$: 5-3-4 kg/lOa. 5. IN TAEGWALLYONG, a northern area of Korea, the average fresh matter yield of the six cultivars tested amounted to 3,500 kg/lOa when drilled on June 30 and harvested on Aug. 30, although bulb formation during the summer was relatively poor. 6. Concluded, forage turnip is regarded to be a suitable catch-crop which has the potential to maintain and increase the total forage production in mid-northern area of Korea. The intercropping is recommendable especially for autumn planting well past the time forage corn has been harvested.

• 대한원격탐사학회지
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• 제22권2호
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• pp.123-129
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• 2006

고해상도 컬러항공영상은 공간정보생성을 위한 지형의 상세한 정량적 및 정성적 정보를 제공해준다. 하지만 도심지역에서 빌딩 또는 숲에 의한 그림자의 발생으로 인하여 지물 추출 및 분류시 부정확한 결과를 초래 시킬 수 있다. 현재까지 그림자 효과에 대한 여러 연구가 이뤄졌으나 도심지에서 그림자의 발생으로 야기된 분광정보 왜곡의 문제점을 해결하여 도로추출에 대한 연구가 매우 부족한 실정이다 본 연구에서는 컬러항공사진과 LIDAR(LIght Detection and Ranging) 고도 자료를 이용하여 아스팔트 도로 경계선을 추출하는 기법을 제안하였다. 구체적으로 그림자 영향의 제거를 통한 아스팔트 도로 경계선의 추출과정은 다음과 같다. 첫 번째, 항공사진에서 그림자 영역을 LIDAR자료부터 생성된 DSM(Digital Surface Model)과 태양각으로부터 추출하였다. 그 후 도로영역추출기법, 경계선 검출기법을 통하여 도로의 경계를 추출하였으며 이 자료를 벡터화하므로서 GIS벡터의 선분 자료로 생성하였다. 본 연구의 실험결과 제안된 방법은 그림자의 영향을 소거하여 원활한 아스팔트 도로의 경계를 추출하는데 있어서 효과적임을 알 수 있었다.

• 산업경영시스템학회지
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• 제26권3호
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• pp.24-30
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• 2003

As domestic buildings have been large-scaled, diversified and high-rise, there have been a consistent demand for design, development of construction technology and accident prevention activity as well as quality enhancement. In spite of governmental and related institutions' efforts for reducing national losses which come from numerous accidents, there have been endless small and large accidents on the construction site and thus, it is urgent to conduct empirical researches in this area. Currently safety supervision system in construction industry has enforced harm and danger prevention planning system, however it merely stick to other existing materials. In addition, it is difficult to put it into practice in that it requires bearing too much burden to draw out the planning itself in a case of large construction work. Consequently in this paper we select evaluation criteria by construction progress, classify into several categories, and regard potential danger which often occurs, as a evaluation criterion. Further step is to allow workers or collaborated companies to express their expert opinions or experiences and to encourage quality and process control and autonomous safety control by applying PSM(Process Safety Management) method using AHP(Analytic Hierarchy Process) and to development of PSM evaluation method in the construction. The reason why PSM method should be quantitative and substantial progress is because it contributes Korean constructing companies to enhancing their safety control ability and to taking an equal stance just like developed countries, thereby strengthening their competitive edges. Boost of safety control system by PSM method could make an enormous contribution to preventing construction accidents on the site by establishing and securing an autonomous safety control system.

• 국제초고층학회논문집
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• 제10권4호
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• pp.265-283
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• 2021

To ensure that fire induced collapse of a building is prevented it is important to understand the sequence of events that can lead to this event. In this paper, the initiation of collapse mechanisms of generic a multi-storey steel frame subjected to vertical and horizontal travelling fires are analysed computationally by tracking the formation of plastic hinges in the frame and generation of fire induced loads. Both uniform and travelling fires are considered. In total 58 different cases are analysed using finite element software LS-DYNA. For the frame examined with a simple and generic structural arrangement and higher applied fire protection to the columns, the results indicate that collapse mechanisms for singe floor and multiple floor fires can be each split into two main groups. For single floor fires (taking place in the upper floors of the frame (Group S1)), collapse is initiated by the pull-in of external columns when heated beams in end bays go into catenary action. For single floor fires occurring on the lower floors(Group S2), failure is initiated (i.e. ultimate strain of the material is exceeded) after the local beam collapse. Failure in both groups for single floor fires is governed by the generation of high loads due to restrained thermal expansion and the loss of material strength. For multiple floor fires with a low number of fire floors (1 to 3) - Group M1, failure is dominated by the loss of material strength and collapse is mainly initiated by the pull-in of external columns. For the cases with a larger number of fire floors (5 to 10) - Group M2, failure is dominated by thermal expansion and collapse is mainly initiated by swaying of the frame to the side of fire origin. The results show that for the investigated frame initiation of collapse mechanisms are affected by the fire type, the number of fire floors, and the location of the fire floor. The findings of this study could be of use to designers of buildings when developing fire protection strategies for steel framed buildings where the potential for a multifloor fire exists.

• 대한건축학회연합논문집
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• 제20권6호
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• pp.41-46
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• 2018

The context of innovation in which we evolve today, subtracts us in a spacial reality and virtuality (digital) that aimed less and less to interact with natural processes which could converge to new possible relationships in the world. We constantly live in presence of fluctuations and imperceptible natural energies (wind, solar radiation, etc.) defined by flows, their own physicality, which remains without being virtual, elusive. This study first outlines how these energies already exploited within the framework of production, could be thought as interactive of our habitat's space dimension, as a prolongation of a physical and material environment built by men and for men, giving rise to new social, cultural dynamics, and making natural complexity of our space vivid, comprehensible with new visual and physical clues. In recent days, where lifestyles are changing, architecture no longer needs to limit its scope of creation to only built structures. Based on a deeper understanding of human and through new potential advanced technologies (kinetic system, etc), it is time to fundamentally diagnose what environments or devices contribute to our lives. Architecture becomes ${\ll}interface{\gg}$, step up its fundamental role, and newly defines the sturdy image and tectonics of existing environment, establishing a stance to search for a new typology. In the end, building will show two simultaneous and distinctive connections related to its physical existence: reality in its function and irreductibility, in its ability to forge new dynamic connections with its environment, hybridizing the spatial dimension to a new form of physicality, adaptive and incessantly flexible in the dimension time, becoming a vessel for ever changing contemporary lifestyles.