• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.197-204
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• 2014

In this paper an Improved Zero Voltage Zero Current Pulse Width Modulation Forward converter which employs a simple resonance snubber circuit is introduced. A simple snubber circuit consists of a capacitor, an inductor and two diodes. In proposed converter, switch Q1 operates at ZCS turn-on, and ZVS turn-off conditions and all-passive semiconductor devices operate at ZVZCS turn-on and turn-off state. The proposed converter is analyzed and various operating modes of the ZVZCS-PWM forward converter are discussed. Analysis and design considerations are presented and the prototype experimental results of a 100w (40 V/2.5A) proposed converter operating at 30 KHz switching frequency confirm the validity of theoretical analysis.

• Earthquakes and Structures
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• 제9권6호
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• pp.1291-1311
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• 2015

This study investigates the seismic energy dissipation capacity of a hybrid passive damper composed of a friction and a hysteretic slit damper. The capacity of the hybrid device required to satisfy a given target performance of a reinforced concrete moment resisting frame designed with reduced design base shear is determined based on the ASCE/SEI 7-10 process, and the seismic performances of the structures designed without and with the hybrid dampers are verified by nonlinear dynamic analyses. Fragility analysis is carried out to investigate the probability of a specified limit state to be reached. The analysis results show that in the structure with hybrid dampers the residual displacements are generally reduced and the dissipated inelastic energy is mostly concentrated on the dampers. At the Moderate to Extensive damage states the fragility turned out to be smallest in the structure with the hybrid dampers.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.630-635
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• 2008

An urban transit is representative public transportation which lots of people take everyday. Especially, the station of urban transit is one of the very important public civil infrastructures. From the teachings of subway fire disaster occurred at Daegu on 2003, a certain incident might create large numbers of deaths or injuries and a lot of damages to the subway station without having an accurate grasp of emergency situation and doing proper action on the situation. Therefore, the passive surveillance system, which means the present CCTV based system, needs to be changed into the active one. The active surveillance system is the CCTV based system with intelligent softwares which affords to prevent a certain incident or trouble and its aggravation. In this paper, the state of the art of the representative companies developing intelligent softwares and its application sites of Australia and Hong Kong are briefly introduced. Finally, with the consideration of its recent trends, some technical contents for the intelligent surveillance system of domestic urban transit are briefly described.

• 국제초고층학회논문집
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• 제9권1호
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• pp.61-70
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• 2020

After the 1884 Home Insurance building in Chicago and 1889 Tower building in New York, 15 Park Row became the tallest building in the USA in 1899 and it held this record for nine years. Completed just before the arrival of the 20^th century, this building deserves to be recognized for the sophistication of its architecture with respect to contextual understanding of the 19^th century historic texture in Lower Manhattan, its uniquely economical floor plans, and its use of natural ventilation and daylight. The compositional techniques using the proportional analysis of its context reflect the highest level of architectural education of its time by its architect Robert H. Robinson. In addition, it also offers a unique glimpse to the state-of-the-art technology of its time regarding its structure, its use of movement systems that was capable of serving 4000 users.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2001년도 춘계학술대회논문집:21세기 신지식정보의 창출
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• pp.152-158
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• 2001

웹 기반 교수 시스템들은 대체로 수동적이며 정적인 하이퍼텍스트 위주이기 때문에, 학습자 개개인의 학습 능력에 따른 적응력 있는 학습 환경을 제공할 수 없다. 본 연구에서는 학습 자들의 학습 상황을 효과적으로 파악하고, 학습 결과에 따라 학습자 개개인의 특성에 맞는 동적인 학습 내용을 구성하여 제공할 수 있는 지능형 교수 시스템을 제안한다. 본 시스템은 에이젼트를 기반으로 설계되었으며, 학습을 위한 코스웨어 지식을 효과적으로 구성하여 학습 평가에 따른 적절한 피드백을 추론하여 학습자에게 지원하도록 하고 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.988-993
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• 2004

This paper considers corrosion problems in the bolt connection of weathering steel box girder bridge using the external electric type corrosion resistance method which resisted to local corrosion in coated steel surface with contacted air. The weathering steel was created a rust itself in the passive state. but a coated box girder type was easily dew form could be made galvanic cell that accelerated corrosion. so that it was ruled by protection coat with some paint. Therefore, it needed that can be applied the external electric type corrosion resistance method in coated surface. As a result of the test of polarization amount had measured that the weathering steel was higher currents than the general steel by about $5\~10\%$. Therefore. an external electric type corrosion resistance method can be used to protect local corrosion in the coated bolt connection of weathering steel box girders effectively.

• 한국군사과학기술학회지
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• 제14권3호
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• pp.372-379
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• 2011

Estimating underwater target state variables(position, velocity, course, etc) is necessary to counteract threatening targets. In passive sonar systems, conventional target motion analysis(TMA) techniques using bearing and frequency measurements of an underwater target are widely introduced. However, it is not clear how conventional TMA techniques can be used if some of frequency measurements are unavailable during parts of the scenario, partially unavailable frequency measurements are common in the ocean with complicated acoustic conditions where frequency measurements often come and go. This paper proposes a new TMA algorithm, which is robust to partially unavailable frequency measurements, using the frequency measurements fusion method.

• Journal of Power Electronics
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• 제9권4호
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• pp.567-574
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• 2009

A linear transfer function for the output current control of frequency-controlled resonant inverters is proposed in this paper. The circuit of resonant inverters can be transformed into two coupled circuits through the complex phasor transform. The circuits consist of cross-coupled power sources and passive elements. The circuits are used to induce the state space equation, which is transformed into the $4^{th}$ order cross-coupled transfer function. The $4^{th}$ order cross-coupled transfer function is modeled into a $2^{nd}$ order linear transfer function based on a behavior analysis of the pole and zero locations that facilitate a simple and intuitive linear transfer function. The feasibility and validity of the proposed linear transfer function were verified by simulation and experiment.

• Transactions on Electrical and Electronic Materials
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• 제7권3호
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• pp.108-111
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• 2006

The oxidizer-induced corrosion state and microstructure of surface passive metal-oxide layer greatly influenced on the removal rate of tungsten film according to the slurry chemical composition of different mixed oxidizers. In this paper, the actual polishing mechanism and pH-potential equilibrium diagram obtained from potentiodynamic polarization curve were electrochemically compared. An electrochemical corrosion effect implies that slurries with the highest removal rate (RR) have the high dissolution rate.

• Wind and Structures
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• 제2권3호
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• pp.201-251
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• 1999

Flexible structures may experience excessive levels of vibration under the action of wind, adversely affecting serviceability and occupant comfort. To ensure the functional performance of a structure, various design modifications are possible, ranging from alternative structural systems to the utilization of passive and active control devices. This paper presents an overview of state-of-the-art measures that reduce the structural response of buildings, including a summary of recent work in aerodynamic tailoring and a discussion of auxiliary damping devices for mitigating the wind-induced motion of structures. In addition, some discussion of the application of such devices to improve structural resistance to seismic events is also presented, concluding with detailed examples of the application of auxiliary damping devices in Australia, Canada, China, Japan, and the United States.