• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.377-384
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• 2008

In the bi-directional pile load test (BD PLT) for pile load test of Mega foundation, loading capacity specification were not specified exactly. Therefore there are so many confusions and variations of maximum 2 times in loading capacity are come out. In this study, specifications of bi-directional pile load test (BD PLT) were considered. Based on cases of the bi-directional pile load test performed in domestic areas, maximum equivalent test load, test load increasing ratio and sufficiency ratio of design load were analyzed. It can be known that the loading capacity specification of bi-directional pile load test must be defined as 1-directional test load that is established as more than 2 times of design load.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.343-350
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• 2006

This paper introduces a new high efficient bi-directional, non-isolated DC/DC converter. Through variations of the topology of the conventional Cuk converter, an optimum bi-directional DC/DC converter is proposed. Voltage and current in the proposed DC/DC converter are continuous. Furthermore, the efficiency in both step-up and step-down mode is improved over that of the conventional bi-directional converter. To prove the validation for the proposed converter, simulations and experiments are executed with a 300W bi-directional converter.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1156-1163
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• 2010

The bi-directional high pile load test(BDH PLT) does not have weaknesses found in the existing bi-directional low pile load test(BDL PLT); it has strong economics, is unbound by load capacity limit and secures quality stability of working piles. In this study, Verification the field found a very high capacity level of stability and reliability of the BDH PLT, as well as outstanding field applicability. Field verifications reaffirmed the advantage of the BDH PLT device, which was capable of loading 90 MN capacities as maximum. It was also found to be durable enough to load high capacity with ease.

• IEIE Transactions on Smart Processing and Computing
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• 제3권5호
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• pp.285-297
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• 2014

This paper presents the results of an investigation into bi-directional communication in spectrum sharing-based cognitive radio (Bi-CR) systems. A Bi-CR system can increase the spectral efficiency significantly by sharing the spectrum and through the bi-directional use of spatial resources for two-way communication. On the other hand, the primary user experiences more interference from the secondary users in a Bi-CR system. Satisfying the interference constraint by simply reducing the transmission power results in performance degradation for secondary users. In addition, secondary users also experience self-interference from echo channels due to full duplexing. These imperfections may weaken the potential benefits of the Bi-CR system. Therefore, a new way to overcome these defects in the Bi-CR system is needed. To address this need, this paper proposes some novel power allocation schemes for the Bi-CR system. This contribution is based on two major analytic environments, i.e., noise-limited and interference-limited environments, for providing useful analysis. This paper first proposes an optimal power allocation (OPA) scheme in a noise-limited environment and then analyzes the achievable sum rates. This OPA scheme has an effect in the noise-limited environment. In addition, a power allocation scheme for the Bi-CR system in an interference-limited environment was also investigated. The numerical results showed that the proposed schemes can achieve the full duplexing gain available from the bi-directional use of spatial resources.

• 인터넷정보학회논문지
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• 제12권3호
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• pp.69-76
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• 2011

온라인 중개 서비스 시스템에서 원하는 고객을 상호 매칭시키는 기능은 핵심 역할 중의 하나이다. 매칭은 정보검색과 같이 한쪽의 의사만으로 결정되는 단방향과, 양쪽 사용자의 의사를 모두 고려하는 양방향 방식이 있다. 기존의 양방향 방식은 사용자가 상대에 대한 관심을 직접 입력하여야 하므로 입력의 번거로움 뿐만 아니라 상대가 나에 대해 관심을 입력하지 않은 경우는 서비스 활용이 어렵다는 문제점이 있었다. 따라서 본 연구는 퍼지 알고리즘을 이용하여 시스템이 상대의 흥미를 자동으로 계산하도록 하여 양방향 방식을 자동화 하고자한다. 개발된 퍼지 알고리즘의 구인/구직 정보매칭 결과가 모두 95%이상의 취업알선가능률을 보였다. 또한 실 서비스에 구축하여 도입효과를 분석한 결과 취업활동 동기 부여에 통계적으로 유의미한 긍정적인 효과가 나타났다.

• Coupled systems mechanics
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• 제5권2호
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• pp.101-126
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• 2016

Seismic structural fragility constitutes an important step for performance based seismic design. Lateral load-resisting structural members are often analyzed under one component base excitation, while the effect of bi-directional shaking is accounted per simplified rules. Fragility curves are constructed herein under real bi-directional excitation by a simple extension of the conventional Incremental Dynamic Analysis (IDA) under uni-directional shaking. Simple SODF systems, parametrically adjusted to different periods, are examined under a set of near-fault and far-fault excitations. Consideration of bi-directional interaction appears important for stiff systems. Further, the study indicates that the peak ground accelertaion, velocity and displacement (PGA, PGV and PGD) of accelerogram are relatively stable and efficient intensity measures for short, medium and long period systems respectively. '30%' combination rule seems to reasonably predict the fragility under bi-directional shaking at least for first mode dominated systems dealt herein up to a limit state of damage control.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.319-324
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• 2012

This paper presents the study of 3-Phase bi-directional DC to AC inverter with unity power factor. 3-Phase bi-directional DC to AC inverter is important for the bi-modal PV PCS with an energy storage system. Both Inverting and converting are needed to connect between the grid side and boost converting side to charge and discharge the energy storage system. The paper proposes the appropriate circuit topology and proper control system for the bi-directional inverter. It also proposes the method of selecting the optimum control method considering system stability. PSIM simulation is used to validate the proposed algorithm.

• Journal of Power Electronics
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• 제18권4호
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• pp.1190-1200
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• 2018

A current sourced bi-directional wireless power transfer (WPT) system is proposed to solve the problems that exist in the bi-directional WPT for vehicle-to-grid (V2G) systems. These problems include the fact that these systems are not safe enough, the output power is limited and the control methods are complicated. Firstly, the proposed system adopts two different compensation and control methods on both the primary and secondary sides. Secondly, based on an AC impedance analysis, the working principle is analyzed and the parameter configuration method with frequency stability is given. In order to output a constant voltage, a bi-directional DC/DC circuit and a controllable rectifier bridge are adopted, which are based on the "constant primary current, constant secondary voltage" control strategy. Finally, the effectiveness and feasibility of the proposed methods are verified by experimental results.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1692-1699
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• 2015

This paper presents an analysis of the mechanism of failure modes in bi-directional phase-shift full-bridge converters, composed of MOSFET, based on the circuit operation and parasitic parameters of MOSFET. In addition, the relation between circuit operation and parameters is suggested through an experimental comparison. From this relation, the suitable ranges of parameters for stable performance are analyzed. The design criteria of the bi-directional phase-shift full-bridge converter are presented and evaluated from the experimental verification.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.585-591
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• 2016

DOCR can be used to efficiently increase the reliability and to protect the bi-directional D/L(Distribution Lines). As more DG(Distributed Generation)s attempt to connect the bi-directional D/L, there is an increasing need for studies of how to use DOCR installed in the D/L. This paper investigates the operating principles of DOCR and presents the results an effect of sequence and fault impedance in L-L(Line to Line) fault. An advanced DOCR operating algorithm is proposed to reduce the mal-operation of conventional DOCR. The proposed algorithm is applied to the bi-directional power flow system and shows that it decreases the mal-operation of DOCR through the computer simulation.