• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.148-150
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• 2002

The distributed jointing method is used in the underground tunnel due to narrow space of jointing. This method causes non-uniform length between cable joints. It has an effect on the sheath circulating current and the induced voltage. Furthermore the distributed jointing method may cause transient overvoltage resulting from lightning in underground cable which is connected with overhead line. The author diversely studied the sheath circulating current and induced voltage on underground cable depending on the distributed jointing length under the normal and the transient circumstances. The various simulation results really improve the cable system utility.

• 대한전자공학회논문지TC
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• 제40권10호
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• pp.150-158
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• 2003

라인 소스에 의한 빔 패턴 합성 문제에서 소스 분포함수와 빔 패턴간의 관계는 푸리에 변환쌍으로 표현 될 수 있다. 본 연구에서는 원하는 lobe형 빔 패턴을 만족시키는 라인 소스 분포함수를 반복 샘플링을 통한 비선형 역변환법을 사용하여 합성하는 일반적인 방법을 제안한다. 이 방법은 유전 매질에 TE 및 TM 평면파 입사시 원하는 역산란 반사계수를 갖도록 하는 연속적으로 분포된 유전율 합성에 적용될 수 있으며, 임의 반사계수를 갖는 전송선로 합성에도 적용될 수 있는 장점을 가진다. 대역저지 공간 필터 및 분산 특성을 갖는 전송선로 필터에 적용, 분석하므로서 제안한 방법의 타당성을 보인다.

• Journal of Advanced Marine Engineering and Technology
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• 제38권3호
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• pp.302-311
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• 2014

본 연구에서는 소형화된 투명 플렉시블 무선통신소자 구현을 위해, 주기적 구조를 가지는 fishbone 형태의 전송선로를 PES (polyether sulfone) 박막상에 제작하였으며, 이에 관한 RF 특성을 고찰하였다. 그 결과에 의하면, PES 박막상에 제작된 fishbone 형태의 전송선로는 종래의 코프레너선로에 비해 단파장특성을 보여주었으며, 구체적으로 50 GHz에서 선로파장은 2.23 mm으로, 종래의 코프레너 선로의 56.6%이다. 삽입손실 측정결과에 의하면 fishbone 형태의 전송선로는 50 GHz 까지의 주파수 범위에서 1.31 dB보다 낮은 저손실특성을 보여주었다. 대역폭 추출결과에 의하면, PES 박막상의 fishbone 형태의 전송선로는 통과대역이 608 GHz인 광대역 특성을 보였다. PES 박막상의 fishbone 형태의 전송선로의 특성임피던스는 기존의 주기적 구조와는 달리 매우 적은 주파수 의존성을 나타내었으며, 이로 인해 광대역의 전송선로 및 광대역 분포형 수동소자에 이용될 수 있음을 알 수 있었다.

• 한국통신학회논문지
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• 제29권7A호
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• pp.719-726
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• 2004

광섬유의 분산이 균일하지 않다는 가정 하에 색 분산과 자기 위상 변조 (SPM : Self Phase Modulation) 현상에 의해 왜곡된 WDM 채널의 보상 특성을 수치적으로 살펴보았다. 본 연구에서 사용한 보상 기법은 전체 전송 링크 중간에 광 위상 공액기 (OPC： Optical Phase Conjugator)를 두어 보상하는 MSSI (Mid-Span Spectral Inversion)이다. OPC를 중심으로 두 광섬유 구간의 분산 계수 분포가 변동하면서 서로 일치하지 않은 경우에도 전송 채널의 입력 전력을 적절히 조절함으로써 MSSI를 통해 장거리 전송이 가능하다는 것을 알 수 있었다. 즉 장거리 WDM 시스템에 MSSI를 적용하게 되면 전송 선로 곳곳에 필요한 보상기(compensator) 등을 없앨 수 있고, 결과적으로 시스템 비용을 절감할 수 있을 것으로 기대된다.

• ETRI Journal
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• 제24권2호
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• pp.81-96
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• 2002

This paper describes our design of a hybrid amplifier composed of a distributed Raman amplifier and erbium-doped fiber amplifiers for C- and L-bands. We characterize the distributed Raman amplifier by numerical simulation based on the experimentally measured Raman gain coefficient of an ordinary single mode fiber transmission line. In single channel amplification, the crosstalk caused by double Rayleigh scattering was independent of signal input power and simply given as a function of the Raman gain. The double Rayleigh scattering induced power penalty was less than 0.1 dB after 1000 km if the on-off Raman gain was below 21 dB. For multiple channel amplification, using commercially available pump laser diodes and fiber components, we determined and optimized the conditions of three-wavelength Raman pumping for an amplification bandwidth of 32 nm for C-band and 34 nm for L-band. After analyzing the conventional erbium-doped fiber amplifier analysis in C-band, we estimated the performance of the hybrid amplifier for long haul optical transmission. Compared with erbium-doped fiber amplifiers, the optical signal-to-noise ratio was calculated to be higher by more than 3 dB in the optical link using the designed hybrid amplifier.

• 대한전기학회논문지:전력기술부문A
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• 제52권7호
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• pp.393-400
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• 2003

This paper discusses how to implement and verify a software model of the digital relay that can be added to real time digital simulator(RTDS) model library and is then subjected to the same outputs as the actual relay. The software model is stand-alone and can be used with real relays. It is also possible to conduct interactive real-time tests when the system effects of the relay action need to be investigated. The characteristics of mho type and the quadrilateral type, which is commonly used in recently developed relays, are modeled in this paper. Single circuit line and double circuit line system are used for model verification. The transmission lines are each 100 km in length and are modeled as distributed parameter lines but not frequency dependent. The transmission lines in the single circuit system are modeled as ideally transposed line. The mutual coupling data with the parallel line was taken account in the transmission lines for the double circuit system. The main CTs and PTs are included and operated in their linear region during the tests. For the purpose of testing the relay model accuracy the faults have been applied at various points on the protected line. Its accuracy is assessed against theoretical values.

• 조명전기설비학회논문지
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• 제17권6호
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• pp.31-38
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• 2003

가공송전선로주변 자계저감 기법 중에서 수동루프 방식은 기존 송전철탑에 적은 비용으로 용이하게 적용되어 만족할 만한 저감효과를 제공할 수 있지만 수동루프에 유도되는 전류에 의해 송전손실이 증가될 뿐 아니라 송전선로의 기하학적 비대칭성이 증가됨으로써 상불평형이 증가하게된다. 따라서 본 논문에서는 수동루프 설치에 따른 송전손실과 송전선로 수전단에서의 상불평형을 모의하고자한다. 345[kV]급 수평 상배치 1회선 가공송전선로를 선정하여 수동루프를 송전선로의 선로정수에 포함시킨 비대칭 3상 분포정수 모델로 표현하였으며 이것에 대한 미분방정식을 정의하고 해를 구함으로써 수전단 3상의 전압과 전류를 계산했다. 그 결과로부터 각 상에 따라 전력손실이 다르게 발생하며 수전단에서 정상분이 감소하는 대신에 역상분이 증가함을 확인하였다. 일반적으로 수동루프에 의한 상불평형이 차지하는 비중이 크지는 않지만 수동루프 설치구간과 유도전류의 크기 등에 비례하여 증가하므로 수동루프 도입에 따른 소요비용을 산출하는 과정에서 그에 따른 영향을 포함시켜야 할 것으로 판단된다.

• 대한전기학회논문지:전력기술부문A
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• 제50권9호
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• pp.424-430
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• 2001

A multi-level optimal power flow(OPF) algorithm has been evolved from a simple two stage optimal Power flow algorithm for constrained power economic dispatch control. In the proposed algorithm, we consider various constraints such as ower balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the two stage optimization method to an average gain of 2.99 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.926-928
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• 1998

A fast optimization algorithm has been evolved from a simple two stage optimal power flow(OPF) algorithm for constrained power economic dispatch. In the proposed algorithm, we consider various constraints such as power balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the coupled LP based OPF method to an average gain of 53.13 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

• 대한전기학회논문지:전력기술부문A
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• 제53권9호
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• pp.481-486
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• 2004

In operation of distribution system, $DG_s$ Distributed Generations) are installed as an alternative of extension and establishment of substations and transmission and distribution lines according to increasing power demand. In operation planning of $DG_s$, determining optimal capacity and allocation gets economical pro(it and improves power reliability. This paper proposes determining a optimal number, size and allocation of $DG_s$ needed to minimize operation cost of distribution system. Capacity of $DG_s$ (or economical operation of distribution system estimated by the load growth and line capacity during operation planning duration, DG allocations are determined to minimize total cost with power buying cost. operation cost of DG, loss cost and outage cost using GA(Genetic Algorithm).