• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.384-387
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• 2009

There is an increasing demand for efficient high power/weight auxiliary power supplies for use on high speed traction application. Many new conversion techniques have been proposed to reduce the voltage and current stress of switching components, and the switching losses in the traditional pulse width modulation (PWM) converter. Especially, the phase shift full bridge zero voltage switching PWM techniques are thought must desirable for many applications because this topology permits all switching devices to operate under zero voltage switching(ZVS) by using circuit parasitic components such as leakage inductance of high frequency transformer and power device junction capacitance. The proposed topology is found to have higher efficiency than conventional soft-switching converter. Also it is easily applicable to phase shift full bridge converter by applying an energy recovery snubber consisted of fast recovery diodes and capacitors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.839-842
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• 2009

통신선에 장애를 유발할 수 있는 전자유도 대책을 위해서 국가 기술기준에 의한 유도전압 한계치가 정해져 있고, 현장 유도 대책 상 이 제한치를 초과할 때에 필요한 것이므로 정부 고시의 기술 근거에 의해 유도전압을 계산하여 이에 대한 조치를 시행하고 있다. 전자유도 현상에 있어서 피유도원인 통신선간의 커플링 관계에 있어서 중간 차폐를 줄 수 있는 성분에 대한 계수치를 적용할 수 있다. 이러한 차폐성을 줄 수 있는 시설과 관련하여 여러 가지 기유도원 또는 피유도원 시설 구조상의 요소들에 대한 차폐치가 주어져 있다. 그러나 지중 매설물에 대한 차폐효과에 대하여는 별도로 제시되지는 못하고 있다. 이와 관련 지중 매설물 중 광역상수도관에 의한 차폐성을 확인하기 위한 현장 측정을 통하여 비교 연구하였다. 유도원과 병행하여 광역상수도관이 매설된 지역에서 광역상수도관이 병행하는 부분과 일정 정도의 이격되어 병행하는 부분의 경계점에서 양단에 발생하는 유도 전압을 동시 비교 측정함으로써 그 차폐효과에 대한 현장 데이터를 확보하였다. 현장의 여러 조건변수들의 종속성을 정규화하고 광역상수도관의 독립적 변수에 의한 차폐성을 분석하여 제시한다.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.173-179
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• 2009

High-speed railway is important transportation in the world because it has a lot of merits like as very comfortable, environmental benefits, energy savings, etc. The increase of demand for high-speed railway influence to develop of new hish-speed trains. Many countries introduced new high-speed train in the market and it meets to the market's needs. They adopt new technology and systems like that active suspension, synchronous permanent magnetic motor, distributed drive system, aero acoustics, etc. In Korea, the project for R&D of new high-speed train is launched in 2007. We need analysis for main properties of new high-speed train(HEMU-400x). This paper presents the comparisons, analyzed characteristics of main properties like as traction system and braking system. In this analysis, we can know our technical position in the world and what is important to focus on the development. It is very useful to develop a next generation high-speed train in Korea.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.113-113
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• 2018

환경 친화형 전기자동차, 하이브리드 자동차, 전철 등에서는 고내압 및 소형으로 전력손실을 감소시킬 수 있는 파워 디바이스가 필수이다. 최근, 실리콘 카바이드(SiC, silcon carbide)는 기존 실리콘(Si)보다 스위칭 손실의 저감 및 고온환경에서의 동작 특성이 우수하여, 차세대 저 손실 전력반도체 재료로서 기대를 받고 있다. 용액 성장 법에서 고품질 SiC 결정을 만들 수 있다. 그러나 늦은 성장 속도 때문에 SiC의 양산을 어렵게 하고 있다. 현재까지 성장 속도 향상을 위한 Si용매에 Cr을 첨가하여 탄소 용해도를 높이는 방법이 사용되고 안정된 성장을 위한 Si-Cr용매에 Al를 첨가하는 등 다양한 금속을 첨가하는 방법이 이용되고 있다. 선행 연구에서는 다양한 용매인 탄소 용해도를 실측하고 특히 큰 탄소 용해도를 보인 것은 Co이었다. 본 연구에서는 $Si_{0.6}Cr_{0.4}$원료와 Co를 첨가한 $Si_{0.56}Cr_{0.4}Co_{0.04}$의 용매에 의한 SiC용액 성장을 실시하고 결정 성장 속도 및 표면 상태의 변화를 검토했다. on-axis 4H-SiC(000-1)을 사용한 Top-seeded solution growth(TSSG)법과 원자 비율로 $Si_{0.6}Cr_{0.4}$와 $Si_{0.56}Cr_{0.4}Co_{0.04}$의 용매를 이용하여 SiC 용액 성장을 실시했다. Ar가스에서 저항 가열로 내를 치환 후에 $1800^{\circ}C$까지 가열하고 종자화 후에 120분간 유지하고 결정 성장을 실시했다. 냉각 후에 성장의 표면에 남은 용매를 $HF+HNO_3$에서 제거했다. 광학 현미경을 이용하여 결정면과 두께를 관찰 측정했다. Co를 첨가한 $Si_{0.56}Cr_{0.4}Co_{0.04}$의 경우는 $Si_{0.6}Cr_{0.4}$의 경우보다 결정 성장 속도가 향상됐다. 또한 $Si_{0.6}Cr_{0.4}$보다 step-flow의 성장을 나타낸 결정의 표면이 전반적으로 관찰됐으며 안정된 결정성장을 나타냈다. 본 연구에서 실시한 연구 방법과 결과는 고품질 및 고속의 SiC 용액성장을 위한 매우 유용한 자료로 활용 될 수 있을 것으로 판단한다.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.623-630
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• 2009

The Korean railway system is a mass transit system consisting of a variety of train types such as common trains, high-speed train (KTX) and Metropolitan Express Railway (EMU). Its operation is based on the official timetable and it provides us with safe, accurate, quick and comfortable service. The objective of this study is to propose and prove more practical method for estimating line capacity by considering high-speeding and diversification of trains. In particular, the focus of this study is to reduce the discrepancy between the result of the theoretical line capacity estimation and the real line capacity of the operating agency of the Korean railway. In order to achieve the object, this study introduces a new railway capacity notion by considering TPS of line alignment, the operation type, train control and signaling system, etc. Through a practical schedule diagram exemplification, the result of the proposed method is verified as well.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1839-1850
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• 2009

The Korean railway system is a mass transit system in which a various types of trains such as common trains, high-speed train (KTX), Metropolitan Express Railway (EMU) are operated. It is operated based on a timetable and provides us with safety, regularity, quickness and comfortable service. The objective of this study is to propose a method for estimating line capacity considering high-speeding and diversification of trains. In particular, the focus of this study is on the closing gap between the result of the existing line capacity estimation method and the real-world line capacity of the operating agency of the Korean railway. For this, this study introduces a new railway capacity definition by considering TPS of line alignment according to the operation type, train control and signaling system, etc. The verification of the proposed method using a practical schedule diagram exemplification is discussed as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7B
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• pp.601-607
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• 2008

The induced voltages by AT power feeding system of electrified traction line to telecommunication line are calculated with the method of multi-conductor line solution in the CCITT Directives. There is a screening effect by railway line itself among various shielding factors against induction. It is the argue point whether the multi-conductor line solution contains the railway line effect since the calculation method does not show any expression about shielding factors. So this paper illuminates the mysterious question by reviewing the shielding factor principle on traction system, scrutinizing the Japanese bible about induction, analyzing the multi-conductor line solution itself, and comparing the result calculation considering the effect of railway screen. This paper concludes that multi-conductor line solution contains the screening effect of railway lines.

• Archives of design research
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• v.17 no.2
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• pp.43-54
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• 2004

The appreciation of cultural properties related with what the aspects of society was is mandatory to understand our culture correctly. To make over all cultural properties to our descendants without breakage or damage is our natural duty and national obligation. On the contrary, inhabitants in the preserved area should be restricted and controlled by the cultural property law. The conflict between the inhabitants in the preserved area and the government raises economical problems and damages all the time. Especially it is time to discuss to mediate between them and solve the problems. This feasible study is a proposal to settle them up through renovating abolished school in the preserve area to the museum and a case to preserve the cultual properties as well as habitant's assets in that area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.666-671
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• 2018

A honeycomb panel is a plate made by attaching two surface plateson eitherside of a honeycomb core. The honeycomb plate hasexcellent specific strength and energy absorption and is suitable for use in regions where good impact resistance is required. Recently, with the increasing the need for a lightweight design to facilitate transportation, numerous studies have been conducted using aluminum honeycomb plates as body materials for vehicles such as automobiles and high-speed trains. In addition, honeycomb plates have excellent sound deadening properties, as well as excellent heat insulation and durability. Savings in weight using lightweight materials such as aluminum alloy for honeycomb panel's skin can lead to increase fuel economy and reduction in air pollution. In this study, in order to improve the design technology of the honeycomb plate material, the manufacturing technology of the aluminum honeycomb core and honeycomb plate material and various mechanical properties of the honeycomb plate were evaluated. From the results, it was found that the design of the manufacturing process of the aluminum honeycomb plate, as well as itsproduction and characteristics, were improved. The resulting excellent energy absorption capability of the honeycomb plate was due to the repetitive core buckling, indicating that the higher the compressive strength, the higher the strength per bonded area.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.76-84
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• 2017

Recently, the 'Ecological Network Restoration Project at Chupungnyeong' has been placed; this project is located at the center of the Baekdu mountain spine, the core of the ecological network of the Korean Peninsula. In the process of industrialization since the early 1900s, this area has been under railroad and road construction; as such, wildlife movements have been interrupted and many cases of road-kill have been found. The investment in railroads has increased because railroads are an environmentally sound means of transportation. Single track railways have been converted to double track electric railways and track reforming projects are underway in order to speed up the current railway system. This study suggests to take land use as a standard for assessing the ecological weaknesses of the domestic geo-spaces that are to be affected by rapid extension of railway lines. The land cover map issued by the Ministry of Environment was overlapped with the Korean Railway Line Map for analysis. The results showed that five items were high in sensitivity: paddy fields, fields, deciduous forests, bare land, and inland waters. It seems to be necessary to set weights for highly sensitive land use types; also, specific evaluation criteria need to be reestablished.