• 전기학회논문지P
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• 제56권2호
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• pp.109-114
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• 2007

This paper summarize about the auxiliary electrode measured a ground resistance. The method to measure a ground resistance is the fall-of-potential method to using an auxiliary electrode. And an auxiliary electrode must be set up on the ground. Today it is so difficult to set up the auxiliary electrode on the ground because of many concrete building and many paved roads. So this paper is regarding a trust analysis of the ground resistance measurement by the substitute auxiliary electrode. It substituted a iron structure around the building, a neutral line multiplex ground to earth, a wire net for auxiliary electrode. This information is confirmed bv compared with the measurement value.

• 전기학회논문지
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• 제60권9호
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• pp.1656-1662
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• 2011

In a previous paper, the EMTP modeling technique using search coil test is established through various transient analysis including system grounding condition and grounding resistance for HVDC submarine cables. It was also proved by comparison with real test results. Based on this EMTP modeling technique, in this paper, it will be applied for modeling of ${\pm}180kV$ real HVDC submarine system(Jeju~Haenam). This paper variously analyses the effects of fault resistance including the resistance between core and sheath, the resistance between sheath and amore and the resistance between amore and sea water through EMTP modeling of search coil method. The results can contribute to the accuracy of detailed fault point prediction of search coil test for HVDC submarine cables.

• 조명전기설비학회논문지
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• 제16권4호
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• pp.117-123
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• 2002

접지저항의 측정은 접지계통의 접지성능이 적정한가를 평가하기 위한 가장 기본적이고 중요한 작업이라고 할 수 있다. 그러나 실제 현장에서, 특히 접지극의 크기가 큰 경우일수록 접지저항을 정확히 측정하기란 쉽지 않은데, 이는 정확한 접지전위 측정을 위한 기준전위 점을 찾기가 힘들기 때문이다. 본 논문에서는 접지극 주변에서 측정한 지표면전위를 분석하여 기준전위 점의 위치를 정확히 식별하는 방법과 그 정당성을 제시하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권2호
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• pp.101-109
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• 2005

The newly developed speed sensorless control scheme is proposed to estimate both motor speed and rotor resistance simultaneously using variable rotor flux. The rotor flux is given as sinusoidal waveform with an amplitude and a frequency without affecting precise torque control. Especially the proposed method makes the simultaneous estimation of rotor resistance and speed with high precision even though at the low speed area including a few rpm. Moreover, on-line identification of rotor resistance can be performed simply without calculating troublesome trigonometric functions and complicated integral computation. Therefore, the proposed system can be accomplished by using very cheap microprocessors for several applications. The results of the numerical simulations and experiments demonstrate that this method is effective to estimate the speed and on-line identification of rotor resistance for sensorless induction motors.

• 한국항행학회논문지
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• 제27권2호
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• pp.203-208
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• 2023

본 연구에서는 정전류 회로와 전압 강하법을 이용한 접촉 저항 측정 회로의 정밀도를 개선하는 방법을 제안하고, MQTT 브로커 서버를 통해 접촉 저항 측정 시스템의 측정값을 모니터링할 수 있는 대시보드를 구현한다. 접촉 저항 측정 시스템은 저항값을 측정하고 무선통신을 이용해 MQTT 브로커 서버로 측정값을 전달하고, 대시보드는 Node-RED와 Node-RED-Dashboard을 이용하여 최대 4개의 접촉저항 측정 시스템의 저항값을 받아 이를 사용자 화면에 출력하여 보여준다. 사용자는 하나의 대시보드를 이용해 복수의 측정 데이터를 관리할 수 있고, MQTT 브로커 서버를 통해 다른 장치와 쉽게 인터페이스 가능하게 한다. 실제 데이터 측정을 통해 정밀도 상대표준편차가 평균적으로 40.37%, 그리고 최대 64.73% 각각 감소하여 정밀도의 개선 효과가 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.294.2-294.2
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• 2016

Graphene, a sigle atomic layered structure of graphite, has drawn many scientific interests for attractive future electronics and optoelectronics beyond silicon-based technology because of its robust physical, optical, and electrical properties. But high metal-graphene contact resistance prevents the successful integration of high speed graphene devices and circuits, although pristine graphene is known to have a novel carrier transport property. Meanwhile, in the recently reported metal-graphene contact studies, there are many attempts to reduce the metal-graphene contact resistance, such as doping and one-dimensional edge contact. However, there is a lack of quantitative analysis of the edge contact scheme through variously designed patterns with different metal contact. We first investigate the effets of edge contact (metal-graphene interface) on the contact resistance in terms of edge pattern design through patterning (photolithography + plasma etching) and electral measurements. Where the contact resistance is determined using the transfer length method (TLM). Finally, we research the role of metal-kind (Palladium, Copper, and Tianium) on the contact resistance through the edge-contacted devices, eventually minimizing contact resistance down to approximately $23{\Omega}{\cdot}{\mu}m$ at room temperature (approximately $19{\Omega}{\cdot}{\mu}m$ at 100 K).

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.269-274
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• 2022

We prepared carbon nanotube (CNT) paper by a vacuum filtration method for the use of a chip-typed resistor as a precision passive device with a constant resistance. Hybrid resistor composed of the CNT resistor with a negative temperature coefficient of resistance (T.C.R) and a metal alloy resistor with a positive T.C.R could lead to a constant resistance, because the resistance increase owing to the temperature increase at the metal alloy and decrease at the CNT could counterbalance each other. The constant resistance for the precision passive devices should be maintained even when a heat was generated by a current flow resulting in resistance change. Performance reliabilities of the CNT resistor for the precision passive device applications such as electrical load limit, environmental load limit, and life limit specified in IEC 60115-1 must be ensured. In this study, therefore, the rated power determination and T.C.R tests of the CNT paper were conducted. -900~-700 ppm/℃ of TCR, 0.1~0.2 A of the carrying current capacity, and 0.0625~0.125 W of the rated power limit were obtained from the CNT paper. Consequently, we confirmed that the application of CNT materials for the precision hybrid passive devices with a metal alloy could result in a better performance reliability with a zero tolerance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1874-1876
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• 2000

In this paper, the effects of the positions of the current probe on the measurements of the ground resistanc, and potential gradients with fall-of-potential method are described, and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position of the measuring auxiliary probes. The ground resistance is calculated by applying the 61.8% lute using fall-of-potential method.

• 전기학회논문지
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• 제64권1호
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• pp.57-63
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• 2015

Fault currents characteristics contain decaying DC offset. First cycle peak value of fault currents is higher than steady-state fault current value. These characteristics can affect the operation of protective device. To reduce the asymmetric fault current, the method using a series connection of two hybrid-type Superconducting Fault Current Limiter(SFCL) components, an auxiliary SFCL and a main SFCL, has been proposed. The auxiliary SFCL limits the first half cycle fault current, while main SFCL limits the steady state fault currents. This paper proposed a decision method of the optimal insertion resistance of auxiliary and main SFCL components. To verify the effectiveness of proposed scheme, the various simulations are performed by using Electromagnetic Transient Program(EMTP).

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.325-330
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• 2015

With approval from the Asia Pacific Metrology Program Working Group on Materials Metrology (APMP WGMM), an international comparison for sheet resistance standards for silicon wafers was firstly conducted among Korea Research Institute of Standards and Science (KRISS) in Korea, CMS/ITRI in Taiwan, and NIM in China, which are national metrology institutes (NMIs), from August 2011 to January 2012. The sheet resistance values of the standards are $10{\Omega}$, $100{\Omega}$, and $1000{\Omega}$; the measurement was conducted in sequence at KRISS, CMS/ITRI, NIM, and KRISS again using the four-point probe method with single and dual configuration techniques. The reference value for the measurement results of the three NMIs was obtained through averaging the values of the three results for each sheet resistance range. The differences between the reference value and the measured values is within 0.22% for $10{\Omega}$, 0.17% for $100{\Omega}$, and 0.12% for $1000{\Omega}$. Therefore, the international consistency for conducting sheet resistance measurements is confirmed within 0.22% through the APMP WGMM approved comparison.