• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1956-1958
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• 2002

This paper reviews the calculation of induced voltage to a communication line from Power Transmission Line. Power lines, both overhead and underground, often run parallel to weak current lines, such as telecommunication, signal or data transmission systems or protection circuits. The coexistence of both systems in parallel over long lengths is accompanied by the possible induction of significant longitudinal voltage in the weak current line. In order to evaluate a precise induced voltage, this paper indicated problem about coefficient and numerical formula and present some induced voltage production technology standard application.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.665-672
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• 2002

In this paper, the utilization of waste foundry sand produced in the molding process is studied as a backfill material for underground electric utility systems such as concrete box structures and pipe lines for power supply. The physical, chemical and thermal properties for waste foundry sand are investigated for mechanical stability, environmental hazard and power transmission capacity. Also its properties are compared with the natural river sand. The test results show that waste foundry sand can be utilized for underground concrete box structures as a backfill material; however, it can not be applied to underground pipe lines due to high thermal resistivity or low power transmission capacity.

• 대한전기학회논문지:전력기술부문A
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• 제48권11호
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• pp.1429-1433
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• 1999

This paper proposes the FACTS site selection method using subtransmission system reduction. A general method which uses the sensitivity of the variation in voltage and reactive power has been used to determine the location of shunt type FACTS device, but there is a difficulty to finding a proper location due to the overestimation of the effect of sub-transmission systems. Therefore, there is a need to reduce sub-transmission system for finding an effective location of shunt type FACTS devices such as SVC(Static Var Compensator), STATCOM(Static Synchronous Compesator), and so on.

• 대한전기학회논문지:전력기술부문A
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• 제52권1호
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• pp.29-35
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• 2003

This paper presents a fault location algorithm when there are parallel circuits in power system networks. In transmission networks, a fault location method using the distribution factor of fault currents is introduced and in distribution networks a method using direct 3-phase circuit analysis is developed, because the distribution networks are unbalanced. The effect of parallel circuits in fault location is studied in this paper. The effect is important for the range of protecting zones of distance relay in transmission networks and fault location in distribution networks. The result of developed fault location algorithm shows high accuracy in the simulation that using the EMTP.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.67-73
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• 2018

The paper deals with an approach to time domain simulation for closed end at the downstream of pipe, hydraulic lines terminating into a tank and series lines with change of cross sectional area. Time domain simulation of a fluid power systems containing hydraulic lines is very complex and difficult if the transfer functions consist of hyperbolic Bessel functions which is the case for the distributed parameter dissipative model. In this paper, the magnitudes and phases of the complex transfer functions of hydraulic lines are calculated, and the MATLAB Toolbox is used to formulate a rational polynomial approximation for these transfer functions in the frequency domain. The approximated transfer functions are accurate over a designated frequency range, and used to analyze the time domain response. This approach is usefully to simulate fluid power systems with hydraulic lines without to approximate the frequency dependent viscous friction.

• KEPCO Journal on Electric Power and Energy
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• 제5권3호
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• pp.141-147
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• 2019

최근 전력산업에 가장 커다란 이슈는 신재생에너지의 증가이며 이에 따라 전력계통의 수용성을 확보하기 위한 다양한 기술개발이 추진되고 있다. 또한 세계적으로 보다 융통성 있는 친환경 에너지의 활용을 위하여 국가 및 지역간 전력계통을 연계하는 슈퍼그리드의 구성이 추진되고 있다. 이러한 성격이 서로 다른 계통 간에 연계를 위하여 반드시 요구되는 기술이 초고압 직류송전기술이다. 지금까지 국내에서는 육지와 제주도를 해저케이블로 연결하는 HVDC 송전기술이 적용되었으나 동해안의 발전단지에서 수도권의 부하밀집 지역으로 장거리 대용량 전력전송을 위한 직류가공송전 방식의 기술개발이 추진되고 있다. 인구밀도가 높고 산악이 많은 국내 환경을 고려해 최소한의 경과를 활용하여 8 GW 급의 대용량 전력을 전송하기 위해 도체귀로방식의 ${\pm}500kV$ Double Bipole 송전선로 설계기술을 개발하고 이를 적용하기 위한 사업화를 추진하고 있다. 본 논문에서는 세계 최초로 적용 예정인 도체귀로방식의 Double Bipole 송전선로의 설계를 위한 절연특성에 관한 연구를 수행하고 송전선로에 발생하는 다양한 과전압현상에 견디는 공기절연특성을 실증시험을 통하여 검증하고 이를 서술하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.423-425
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• 2005

Te digital simulation of electric power system is a very important tool that can decide a proper protection systems from the design of the systems. Protection systems base on the wrong simulation results can cause a serious danger in the stability of the power system. So, the power system makes for simulation and the actual power system must be maximumly homologized. In this paper, protection relay models used in actual systems were developed in the PSS/E.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.630-642
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• 2017

In this paper, we propose the opportunistic non-orthogonal multiple access (NOMA)-based cooperative relaying system (CRS) with channel state information (CSI) available at the source, where CSI for the source-to-destination and source-to-relay links is used for opportunistic transmission. Using the CSI, for opportunistic transmission, the source instantaneously chooses between the direct transmission and the cooperative NOMA transmission. We provide an asymptotic expression for the average achievable rate of the opportunistic NOMA-based CRS under Rayleigh fading channels. We verify the asymptotic analysis through Monte Carlo simulations, and compare the average achievable rates of the opportunistic NOMA-based CRS and the conventional one for various channel powers and power allocation coefficients used for NOMA.

• ETRI Journal
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• 제28권1호
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• pp.17-30
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• 2006

In time division duplex (TDD) code division multiple access (CDMA) systems, chip-synchronous transmission in the uplink is obtainable, thus leading to free multiple access interference in flat Rayleigh fading channels plus additive white Gaussian noise. This motivates us to develop a novel cooperative transmission strategy that allows single-antenna devices to benefit from spatial diversity using orthogonal signature sequences. The proposed cooperation is applicable to many digital modulation methods and achieves the fullest diversity level, low implementation complexity, and a full data rate. Closed-form bit-error-rate expressions were also derived and compared to simulation results in order to evaluate its validity. A variety of numerical results demonstrated the cooperation's superiority over single transmission under the same transmit power constraint.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.113-116
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• 2000

Phase noise of oscillator gives the performance degradation significantly when a high carrier frequency and low transmission rate are used. The BER(Bit Error Rates) degradation of QPSK(Quadrature Phase Shift Keying) transmission is analyzed with the oscillator phase noise level specified in downstream physical interface of LMDS(Local Multipoint Distribution Services) which is described in DAVIC(Digital Audio Visual Council). The model used for the phase noise is a power-law model. We also investigated the effects of the various transmission rates on system performance. For the transmission rate below 0.5 Mbps, the BER performance is severely degraded and we verified that the transmission rate, 20 Mbps, is adequate for the downstream of LMDS systems.