• 전기학회논문지
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• 제61권3호
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• pp.373-379
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• 2012

This paper presents a fault location algorithm based on the adaptively estimated value of the local sequence source impedance for faults on a parallel transmission line. This algorithm uses only the local voltage and current signals of a faulted circuit. The remote current signals and the zero-sequence current of the healthy adjacent circuit are calculated by using the current distribution factors together with the local terminal currents of the faulted circuit. The current distribution factors consist of local equivalent source impedance and the others such as fault distance, line impedance and remote equivalent source impedance. It means that the values of the current distribution factors can change according to the operation condition of a power system. Consequently, the accuracy of the fault location algorithm is affected by the two values of equivalent source impedances, one is local source impedance and the other is remote source impedance. Nevertheless, only the local equivalent impedance can be estimated in this paper. A series of test results using EMTP simulation data show the effectiveness of the proposed algorithm. The proposed algorithm is valid for a double-circuit transmission line system where the equivalent source impedance changes continuously.

• 천문학회보
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• 제36권2호
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• pp.71.2-71.2
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• 2011

To investigate the properties of the narrow-line regions and the accretion disks of YRGs, we study a sample of 28 young radio galaxies (YRGs) observed with the Kast Double Spectrograph at the Shane 3-m telescope and with the DBSP (Double Spectrograph for the Palomar 200-inch Telescope) at Palomar observatory. In addition we collect an addition sample of 15 YRGs with the optical spectra from the SDSS archive. We present the measured narrow-line region properties based on the various emission line ratios, i.e., [O III]/$H{\beta}$, [N II]/$H{\alpha}$, [S II] 6716/6731, [O I]/[O III], [O II]/[O III] and [Ar III]/[O III], which are useful to constrain the gas properties and the states of the accretion disk. We will discuss the characteristics of YRG.

• 대한전기학회논문지
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• 제45권2호
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• pp.301-309
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• 1996

This paper estimates the electric field effect near 765[kV] AC double transmission line with numerical data. The induced voltage and current of a human and car under who kinds of phase arrangement are calculated when each of two objects is insulated or grounded. When the calculated results of the low-reactance and superposition phase arrangement are compared, it is proved that the induced voltage and current of the former are about 30 [%] smaller than that of the latter. The induced current of a human and car are less than 0.5[mA] which is about 10[%] less than that of the American National Standard Code. Also the induced voltage and current of dead lines by other live lines are calculated. Finally the effective number and position of shield wires to reduce the field in ground level are considered. charge simulation method and surface charge method are used to simulate the 2 or 3 dimensional transmission line model respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1517-1519
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• 1994

This paper describes electrical environmental study of a 765kV double circuit test line. Corona performance on several candidate conductor bundles has been investigated in the corona cage (single phase simulation facility) since 1984. We have known that six RAIL conductor bundle is the most suitable for the 765kV transmission Line, [3] To investigate electrical environmental impact of the future commerciale line, we build a full sacle 765kV test line in 1993. The test results of Audible Noise, Radio Interference, TV Interference from August, 1993 to Jan. 1994 were measured as $48.7[dBA](L_{50})$. $57.4[dB{\mu}V/m]$(Fair weather, $L_{50})$. $14.5[dB${\mu}$V/m]$(Fair weather, $L_{50}$). We have found that the Audible Noise data were very close to the predicted(48.5 [dBA]) by BPA Corona and Field Effects Computer program, however, the RI and TVI data were much higher than predicted(42 [dBmV/m], $7.9[dB{\mu}V/m)$ by the BPA program. We have investigating the reason of the difference. In the constructing of full scale test line, we developed the tubular tower, 765kV test transformer and hardwares of 765kV transmission line insulator strings. Also we will investigate the effects of plants under the 765kV test Line.

• 비파괴검사학회지
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• 제25권5호
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• pp.356-361
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• 2005

본 연구에서 개발한 온도 보상형 double FBG 센서는 서로 다른 브래그 파장을 갖는 두개의 FBG 센서를 직렬로 연결하여 다양한 열적 조건하에서 구조물의 기계적 변형률만을 실시간으로 측정하기 위한 센서이다. 이 센서를 알루미늄 보에 접착하여 다양한 온도 조건에서 변형률 측정 실험을 수행하고, 결과 값을 전기 저항식 변형률 게이지의 결과 값과 비교하였다. 본 연구에서 제작한 온도보상형 double FBG 센서는 온도의 변화에 영향을 받지 않고 기계 변형률 측정을 잘 수행하였다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2008년도 추계학술발표논문집
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• pp.270-273
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• 2008

A small meander line antenna for T-DMB (Terrestrial Digital Multimedia Broadcasting) is presented. The antenna proposed here is based on a typical planar meander line antenna and miniaturized by using a double sided structure. A prototype antenna is manufactured based on the simulation results and the basic performances are measured. The presented antenna designed to operate in T-DMB band (174~216MHz) and can be adopted for various mobile applications.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.8-8
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• 2010

In this paper, the limiting characteristics of the fault current in a power system with a superconducting fault current limiter(SFCL) applied into neutral line of main transformer in a distribution power line were analyzed. The SFCL applied into the neutral line of main transformer power system can limit the unsymmetrical fault current from the single-line ground fault or the double-line ground fault. In addition, it could be decreased a number of SFCL and a load. This method could be expected to reduction of a power loss in the neutral line, because of a neutral line current is zero in ordinary times.

• 한국전기전자재료학회논문지
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• 제23권2호
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• pp.148-152
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• 2010

The superconducting fault current limiter (SFCL) applied into the neural line of a power system, which can limit the unsymmetrical fault current from the single-line ground fault or the double-line ground fault, was reported to be the effective application location of the SFCL in a power system. However, the limiting operation for the symmetrical fault current like the triple line-ground fault is not effective because of properties of the balanced three-phase system. In this paper, the limiting method of the symmetrical fault current in a power system with a SFCL applied into neutral line was suggested. Through the short-circuit experiments of the three-phase fault types for the suggested method, the fault current limiting and recovery characteristics of the SFCL in the neutral line were analyzed and the effectiveness of the suggested method was described.

• International Journal of Ocean System Engineering
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• 제3권4호
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• pp.188-208
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• 2013

The motion response of floating structures should be adequately low to permit the operation of rigid risers along with dry well heads. Though Spar platforms have low heave responses under lower sea state, could become unacceptable in near resonance region of wave periods. Hence the hydrodynamic response, heave in particular, must be examined to ensure that it is minimized. To reduce heave motions, external damping devices are introduced and one such effective damping device is heave plate. Addition of heave plate can provide additional viscous damping and additional added mass in the heave direction which influence the heave motion. The present study focuses on the influence of heave plate on the hydrodynamic responses of Classic Spar in regular waves. The experimental investigation has been carried out on a 1:100 scale model of Spar with single and double heave plates in regular waves. Numerical investigation has been carried out to derive the hydrodynamic responses using ANSYS AQWA. The experimental results were compared with those obtained from numerical simulation and found to be in good agreement. The influence of disk diameter ratio, wave steepness, pretension in the mooring line and relative spacing between the plates on the hydrodynamic responses of Spar are evaluated and presented.

• 한국유체기계학회 논문집
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• 제13권6호
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• pp.51-56
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• 2010

A numerical simulation is carried out to investigate the effect of flow rate variation and performance characteristics of double-suction centrifugal pump. Two types of pump which have different impeller inlet breadth and curvature of the shroud line consist of six blades impeller and shroud ring. Finite-volume method with structured mesh and $k-\omega$ Shear Stress Transport turbulence model was used to guaranty more accurate prediction of turbulent flow in the pump impeller. Total head, power and overall efficiency were calculated to obtain performance characteristics of two types of pump according to the variation of flow rate. From the results, impeller having smooth curve along the shroud line obtained good performance. The lower flow rate, the more circulation region, flow unsteadiness and complicate flow pattern are observed. Complicated internal flow phenomena through impellers such as flow separation, pressure loss, flow unsteadiness and performance are investigated and discussed.