• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.295-297
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• 1998

This paper shows characteristics of fault current division factor $S_f$, which is a ratio of earth- return current to total fault current, at a substation fed exclusively by power cables under unsymmetrical fault condition, such as single line-to-ground fault. In substation grounding system design, $S_f$ is a very important factor determining GPR, touch and step voltage at a substation under fault condition. In case of substations fed by overhead lines, 40-60% of $S_f$ has been typically used, although it is a very conservative value with no other network conditions considered. It is authors' hope that $S_f$ presented in this paper could hopefully be a basic reference in designing of substation grounding system, especially for a substation fed exclusively by power cables.

• 전기학회논문지
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• 제64권12호
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• pp.1818-1823
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• 2015

In this paper, we analyzed the optimal configuration of protection wire that have been installed in the electric railway power supply system. Protection wires are to suppress the ground potential rise when the short circuit fault between contact wire-rail(C-F), and protect the electronics equipments(signalling and communication) that are facility the wayside. The role of protection wires must be feed back quickly the fault current to the substation when a short circuit fault occurs. In this paper, we proposed that only one line to install the protection wire. Comparing how to newly proposed and existing system, most of the performance is similar. The reason is that most of the current flowing in the protection wire near the location where the fault occurred. There is no problem even if in one line for human safe and the low impedance of the return circuit in dimension to ensure the safety of the facility during the fault. To ensure safety during an fault occurs, it is sufficient even by one line. But, In the protection wire of facilities planning it is necessary to design taking into account the potential utility.

• 한국전자파학회논문지
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• 제17권11호
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• pp.1120-1131
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• 2006

본 연구는 combined integration/matrix method에 의해 다양한 접지 시스템의 특성을 모의할 수 있는 수치 해석 기법에 관한 연구이다. Combined integration/matrix method는 접지 시스템을 일정한 길이의 요소로 분할하여 미리 적분을 한 후 적분된 길이 요소 기법에 대해 matrix method를 사용하는 방법으로 연산 시간 및 해석시 에러 발생을 줄일 수 있다. 이를 위해 본 연구에서는 수치 해석시 분할 요소 길이에 대한 오차 분석을 통해 최적의 요소길이 산정 방법을 제시하였으며 이를 통해 실규모 접지 시스템의 다양한 형태의 접지 시스템의 성능 분석이 가능하도록 하였다. 오차 분석을 토대로 접지 전극의 길이와 매설 깊이에 따라 적절하게 요소의 길이를 도출한 결과 분할하고자 하는 요소의 길이는 매설 깊이와 접지 도체의 길이에 주요한 상관 관계가 있음을 알 수 있었으며 본 연구에서 제시한 수치 해석 모델링 방법에 따라 3 % 이내의 해석 정확도를 얻을 수 있었다. 또한, 이를 다중 접지계 해석에 적용하여 현재 산업 플랜트 접지 방식에서 가장 논란이 되고 있는 전원 접지계와 신호/통신 접지계의 공통 접지 및 분리 접지의 영향 평가 등에 활용될 수 있음을 보여주었다.

• 한국재난정보학회 논문집
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• 제14권2호
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• pp.130-140
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• 2018

연구목적: 본 논문에서는 우리사회의 대체 전력 에너지원으로 적합하고 유용하게 활용 할 수 있는 태양광 발전 단지 건설 시 안전 특성화 접지에 관한 설계 기법을 제안하고자 한다. 즉, 태양광 발전 단지 내의 셀 모듈부터 전기실까지 내부 그리드의 신뢰성을 향상하고 최적화 할 수 있는 용도별 안전 접지를 적용한 사례들을 소개하고자 한다. 연구방법: 태양광 발전 단지 내 토양의 대지 고유저항을 분석하고 컴퓨터 프로그램(CDEGS)을 활용해 전격을 일으키는 접촉전압과 보폭전압을 해석하여 안전접지에 관한 계산과 산출방법에 대해 제안한다. 또한, 토양 환경을 고려한 반영구적인 접지전극의 재료 선정에 관한 연구에 중요성을 논하고자 한다. 연구결과: Wenner 4 전극법으로 측정한 데이터 중 3개 지역의 CASE별 대지 고유저항 최대값과 최소값을 얻을 수 있었고 이 두 값으로 토양의 두께를 알 수 있다. 측정된 데이터를 기본수식 ${\rho}=6.28aR$에 대입하여 MATLAB 컴퓨터 프로그램으로 계산하였다. 즉, 최소 저항값의 두께는 접지전극을 설치하기에 가장 유리한 토양 환경임을 판단 할 수 있다. 결론: 본 연구를 통해 지역의 CASE별 태양광 발전소 내부 그리드에 대지 표면에 전위상승을 억제 할 수 있는 접지시스템 설계기법을 제안하였다. 하지만 대지의 고유저항과 접지시스템에 경련변화를 실시간으로 확인 할 수 있는 모니터링 시스템과 빅 데이터를 축적 할 수 있는 스마트 디바이스의 개발이 추가적으로 연구되어야 할 것이다.

• Structural Engineering and Mechanics
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• 제61권6호
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• pp.701-709
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• 2017

Seismic dissipation devices can play a crucial role in mitigating earthquake damages, loss of life and post-event repair and downtime costs. This research investigates the use of ring springs with high-force-to-volume (HF2V) dissipaters to create damage-free, recentring connections and structures. HF2V devices are passive rate-dependent extrusion-based devices with high energy absorption characteristics. Ring springs are passive energy dissipation devices with high self-centring capability to reduce the residual displacements. Dynamic behaviour of a system with nonlinear structural stiffness and supplemental hybrid damping via HF2V devices and ring spring dampers is used to investigate the design space and potential. HF2V devices are modelled with design forces equal to 5% and 10% of seismic weight and ring springs are modelled with loading stiffness values of 20% and 40% of initial structural stiffness and respective unloading stiffness of 7% and 14% of structural stiffness (equivalent to 35% of their loading stiffness). Using a suite of 20 design level earthquake ground motions, nonlinear response spectra for 8 different configurations are generated. Results show up to 50% reduction in peak displacements and greater than 80% reduction in residual displacements of augmented structure compared to the baseline structure. These gains come at a cost of a significant rise in the base shear values up to 200% mainly as a result of the force contributed by the supplemental devices.

• 국제초고층학회논문집
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• 제1권3호
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• pp.203-209
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• 2012

The purpose of this paper is to present the state of practice being used in the Philippines for the performance-based seismic design of reinforced concrete tall buildings. Initially, the overall methodology follows "An Alternative Procedure for Seismic Analysis and Design of Tall Buildings Located in the Los Angeles Region, 2008", which was developed by Los Angeles Tall Buildings Structural Design Council. After 2010, the design procedure follows "Tall Buildings Initiative, Guidelines for Performance-Based Seismic Design of Tall Buildings, 2010" developed by Pacific Earthquake Engineering Research Center (PEER). After the completion of preliminary design in accordance with code-based design procedures, the performance of the building is checked for serviceable behaviour for frequent earthquakes (50% probability of exceedance in 30 years, i.e,, with 43-year return period) and very low probability of collapse under extremely rare earthquakes (2% of probability of exceedance in 50 years, i.e., 2475-year return period). In the analysis, finite element models with various complexity and refinements are used in different types of analyses using, linear-static, multi-mode pushover, and nonlinear-dynamic analyses, as appropriate. Site-specific seismic input ground motions are used to check the level of performance under the potential hazard, which is likely to be experienced. Sample project conducted using performance-based seismic design procedures is also briefly presented.

• 전기기술인
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• 제228권8호
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• pp.52-57
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• 2001

전기설비 분야에서는 사용하는 전압규격과 사용방식, 접지 System이 어떻게 조화를 이루냐에 따라 안전에 대한 확보여부가 결정된다. 지락 사고시 지락전류는 일정한 어느 한 부분으로만 흐르는 것이 아니라 접지저항의 상황에 따라 분류한다. 이러한 이유로 접지사항이 낮으면 안전하고 높으면 위험하다는 일반적인 잘못된 생각이 사고를 크게 확대시킬 수 있다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권10호
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• pp.479-484
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• 2002

Recently it is reported that many a malfunction of ELB which is represented by non-operated type ELB for an impulse wave, is caused by lightning impulse and transient ground potential rise due to nearby lightning strokes. In order to examine the cause of malfunction, 5 samples were investigated experimentally in this study. As each ELB has a different leakage current detecting circuit and wiring method, various characteristics were measured. As a result, all of them brought about malfunctions under the lightning impulse voltage less than 7 kV and the surge current less than 3 kA. Also the different aspects were measured with a polarity of injected surge and a position of MOV to protect the inner circuit of ELB. The Position and effects of protecting devices were suggested as a remedy.

• 국제초고층학회논문집
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• 제9권4호
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• pp.387-396
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• 2020

While tall buildings are an essential building type to accommodate an ever-growing urban population, as buildings become taller and taller, many design challenges arise. As floor spaces are repeated vertically, the occupants' natural horizontal circulation-based social interactions are limited. As buildings become ever taller, safe evacuation to the ground level becomes more challenging in emergencies. With respect to safety as well as serviceability, one of the most fundamental design challenges of exceedingly tall buildings is their structural systems that make the physical existence of tall buildings possible. While many different design solutions can be sought to resolve these issues as well as other design challenges of extremely tall buildings, this paper investigates the potential of conjoined towers to create more livable and sustainable vertical environments. Emphasis is placed on the social and structural capabilities of conjoined towers in providing enhanced social interactions and more efficient ultra-tall structures. The related brief history of conjoined towers is presented. To understand their current status, contemporary design practices of conjoined towers are discussed. Lastly, a new concept of superframed conjoined towers developed for exceedingly tall building complexes is introduced through design studies. Though envisioning future tall buildings is challenging, conjoined towers can be among the strong candidates toward more livable and sustainable vertical urbanism.

• Earthquakes and Structures
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• 제12권1호
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• pp.1-12
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• 2017

Historical earthquakes have shown that successive seismic events may occur in regions of high seismicity. Such a sequence of earthquakes has the potential to increase the damage level of the structures, since any rehabilitation between the successive ground motions is practically impossible due to lack of time. Few studies about this issue can be found in literature, most of which focused their attention on the seismic response of SDOF systems or planar frame structures. The aim of the present study is to examine the impact of seismic sequences on the damage level of 3D multistorey R/C buildings with various structural systems. For the purposes of the above investigation a comprehensive assessment is conducted using three double-symmetric and three asymmetric in plan medium-rise R/C buildings, which are designed on the basis of the current seismic codes. The buildings are analyzed by nonlinear time response analysis using 80 bidirectional seismic sequences. In order to account for the variable orientation of the seismic motion, the two horizontal accelerograms of each earthquake record are applied along horizontal orthogonal axes forming 12 different angles with the structural axes. The assessment of the results revealed that successive ground motions can lead to significant increase of the structural damage compared to the damage caused by the corresponding single seismic events. Furthermore, the incident angle can radically alter the successive earthquake phenomenon depending on the special characteristics of the structure, the number of the sequential earthquakes, as well as the distance of the record from the fault.