• 조명전기설비학회논문지
• /
• 제19권1호
• /
• pp.94-100
• /
• 2005

본 논문은 전류유입위치에 따른 봉상접지전극의 과도 및 실효임펄스임피던스의 특성에 관한 것으로 뇌격전류를 인가하여 실규모 접지봉에 대한 시간영역에서의 성능을 평가하였다. 임펄스전류가 가해진 봉상접지전극의 과도 접지임피던스는 접지저항보다 높게 나타났으며, 접지전극의 길이가 길어짐에 따라 접지저항과 실효임펄스접지임피던스는 감소되었다. 또한 실효임펄스접지임피던스는 짧은 시간범위에서는 급격하게 증가하였다. 접지저항의 저감은 접지시스템의 임펄스임피던스 특성의 개선에 결정적인 역할을 한다. 임펄스전류를 접지봉의 하단에 인가하였을 때 접지봉 전위의 파두부에 고주파의 진동 파형이 포함되고 실효임펄스임피던스는 다른 경우보다 높게 나타났다.

• Coupled systems mechanics
• /
• 제2권1호
• /
• pp.1-22
• /
• 2013

Under thermal environment, Magneto-Electro-Elastic (MEE) material exhibits pyroelectric and pyromagnetic effects which can be used for enhancing the performance of MEE sensors. Recently studies have been published on material constants such as pyroelectric constant and pyromagnetic constant for magneto-electro-thermo-elastic smart composite. Hence, the main aim of this paper is to study the pyroelectric and pyromagnetic effects on behavior of MEE plate under different boundary conditions subjected to uniform temperature. A numerical study is carried out using eight noded brick finite element under uniform temperature rise of 100 K. The study focused on the pyroelectric and pyromagnetic effects on system parameters like displacements, thermal stresses, electric potential, magnetic potential, electric displacements and magnetic flux densities. It is found that, there is a significant increase in electric potential due to the pyroelectric and pyromagnetic effects. These effects are visible on electric and magnetic potentials when CFFC and FCFC boundary conditions are applied. Additionally, the pyroelectric and pyromagnetic effects at free edge is dominant (nearly thrice the value in CFFC in comparison with FCFC) than at middle of the plate. This study is a significant contribution to sensor applications.

• 전기학회논문지
• /
• 제61권9호
• /
• pp.1374-1379
• /
• 2012

Urban rail transit tends to global grounding system in order to control ground potential rise and potential differences between electric equipments. In addition, global grounding system can discharge the large capacity surge current to the ground safely. Since some railway electric equipments are installed all section of line, the global grounding system connected with the connecting grounding wire is more effectively. However, if the fault occurred in the connecting grounding wire area, some dangerous voltage is generated. So, the installation of additional grounding rod will be required. In this study, the global grounding system is simulated using CDEGS program to analyze the divergence spacing of additional ground rod depending on dangerous electric potential characteristics. Grounding net of the each station is modelled in depending on the size of the platform, and the spacing of the connecting grounding rod are compared 50m, 100m, 250m and 400m. Simulation results considering of earth resistivity and underground condition of the connecting grounding wire, spacing of the connecting grounding rod is that less than 250m to spacing of the ground rod was appropriately confirmed.

• 대한전기학회논문지:전력기술부문A
• /
• 제54권12호
• /
• pp.592-596
• /
• 2005

Recently, substations have been constructed in GIS (Gas Insulated Switchgear) and indoor type because of the increasing difficulties of securing locations. In case of urban substations, it is also common that the substations are exclusively fed by underground cables. Sometimes, the infrastructures in urban area, such as communication facilities, are located near substations to be constructed. In this paper, we examined such a case that a branch office building of KT(Korea Telecom) was located near 154 kV underground GIS substation under construction with about 100 meters of the lateral distance between two facilities. GPR (Ground Potential Rise) at the substation and the transferred earth potential at the KT building through the earth in SLG (Single-Line-to- Ground) fault condition were investigated based on a series of computer simulations. The calculated earth potential at a distance of 100 m from the substation was below 120 V which satisfying the limit value of 650 V.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권8호
• /
• pp.426-432
• /
• 2004

This paper presents a systematic approach of measurement, modeling and analysis of grounding system impedance in the field of lightning protection system and intelligent power equipments. The measurement and analysis system of ground impedance is based on a computer aided technique. The magnitude and phase of ground impedance were determined by the novel measurement and analysis using the revised fall-of-potential method. The ground impedances of the ground rod of 50 m long are considerably dependent on the frequency. The ground impedance is mainly resistive in the frequency range of 3-20 kHz. At higher frequencies, the reactive components of the ground impedances are no longer negligible and the inductance of the ground rod was found to be the core factor deciding the ground impedance. Although the steady-state ground resistance of the ground rod of 50 m was less than that of the ground rod of 10 m, the ground impedances of the ground rod of 50 m over the frequency range of more than 60 kHz were much greater than those of the ground rod of 10 m. Furthermore, the equivalent circuit model based on the measured data was proposed. and the calculated results were in approximately agreement with the measured data.

• 한국중재학회지:중재연구
• /
• 제28권2호
• /
• pp.217-248
• /
• 2018

This paper reviews the Supreme Court of Japan in Decision of December 12, 2017, 2016 (Kyo) 43 (2011) concerning arbitrator's duty of disclosure and reasonable investigation under the Japan Arbitration Act (Arbitration Act). The Supreme Court of Japan recently issued a precedential decision interpreting, for the first time, the arbitrator disclosure requirements of the Arbitration Act. Under Article 18(4) of the Arbitration Act, arbitrators have an ongoing obligation to disclose circumstances which may give rise to justifiable doubts as to their impartiality or independence. The Supreme Court held that Article 18(4) of the Arbitration Act - requiring arbitrators to disclose all "facts likely to give rise to doubts as to his/her impartiality or independence" - (1) is not satisfied by blanket disclosures or advance waivers of potential future conflicts, and (2) requires disclosure of facts both known to an arbitrator or "that can be normally ascertained by an investigation that is reasonably possible${\cdots}$" This new standard presents opportunities and challenges for enforcing arbitration awards in Japan, and suggests measures that both arbitrators and parties can use to protect their awards. Also, the Supreme Court's new standards for evaluating arbitrator conflict disclosures suggest some measures that both arbitrators and parties to arbitration in Japan can take to protect the enforceability of their awards. The key factual question posed by the Supreme Court's ruling was whether an arbitrator's conflicts check was reasonable. Maintaining records regarding a review of potential conflicts or any investigation provides a ready source of proof in case of a future challenge. The Supreme Court has spoken clearly that so-called advance waivers of potential conflicts are not effective under Japanese law. Instead, to the extent that potential conflicts arise during the course of arbitration, they should be specifically disclosed.

• 조명전기설비학회논문지
• /
• 제20권4호
• /
• pp.72-77
• /
• 2006

본 논문은 인하도선의 설치에 따른 접지시스템의 임펄스전류에 대한 과도임피던스 특성을 다루었다. 임펄스전류를 심매설 봉상 접지전각과 그리드 접지전극에 인가하였을 때 임펄스전류의 상승시간과 인하도선의 길이에 따른 전위상승과 실효임펄스접지임피던스를 측정하고 분석하였다. 과도접지임피던스는 접지전극의 형상과 크기 및 임펄스전류의 파형과 인하도선의 길이에 강하게 의존하며, 인덕턴스가 최소화되도록 인하도선을 설치하는 기법이 과도접지 임피던스의 저감을 위한 중요한 요소이다.

• Architectural research
• /
• 제18권4호
• /
• pp.151-155
• /
• 2016

It is necessary to improve the performance of buildings with respect to the energy efficiency while improving the quality of occupants' lives through a sustainable built environment. During the design and development process, building projects must have a comprehensive, integrated perspective that seeks to reduce heating, cooling and lighting loads through climate-responsive designs. The aim of this study is to find an optimal thermal transmittance (U-values) for building envelope elements for low energy multi-rise residential buildings in the early design phase in Korea. The study found that using small U-values of $0.15w/m^2K$ for exterior walls, ceilings and floors and $1.0w/m^2K$ for south and north facing windows has resulted in energy reduction of 22.1%-59.4% in the south facing rooms and 43%-77.6% of the north facing rooms. It has also found the energy load reduction potential of using small U-values are higher on the north facing rooms. The findings of this study can be suggested to be used as a baseline case for low energy consumption studies. It can also be used to determine appropriate envelope materials and insulation values.

• 한국항해학회지
• /
• 제17권1호
• /
• pp.37-48
• /
• 1993

When the vessel is running at the very low Froude numbers, the free-surface is difficult to be disturbed, wave-making is negligible, and the double -model velocity potential gives a very good approximation for calculating the velocity distribution just outside the boundary layer. If the speed of incident flow is gradually increased, the most perceptible change is the rise of the flow surface at stem. With further increase in speed, the nature of the flow at the bow changes completely, The flow ahead of the bow becomes more distrubed, the rise at the stem to stagnation height disappear, and the first wave crest, of less than the stagnation height, appears a small distance downstream from the stem. The present study is concerned with a small region of this flow, mainly in the bow region. The present investigation is primarily an experimental study of the flow in the bow region of s ship model, and it is undertaken in order to investigated systematically, the effect of bow geometry on this flow. The long-range objective is to use these results to guide the development of a mathematical model for predicting the flow about a ship's bow.

• 전자공학회논문지T
• /
• 제36T권2호
• /
• pp.70-76
• /
• 1999

최근에 휴대전화기가 저 연령층까지 널리 보급되어 어린이들의 두부내에 열점(hot-spot)형성문제가 염려되고 있는 실정이다. 전자파의 인체영향이 체온상승의 열적작용에 의한 것이라고 생각한다면 휴대전화기에 의해 발생하는 두부내 국소SAR의 인체영향도 두부의 온도상승과 연관된다고 추정된다. 본 논문은 휴대전화기를 실사용 상황에서 시간대별 두부의 국소부위에 대한 온도변화를 측정하였다. 그 결과 휴대전화기의 통화시작점에서 계속적인 온도상승을 보이다가 통화가 끝나는 시점에서 두부의 국소적인 온도변화는 빠르게 회복되지만 생체전신의 평균온도는 상승함을 알 수 있었다.