• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.324-327
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• 2002

For the characterization of arbitrary shaped printed circuit board, lossy transmission line grid model based on SPICE netlist and analytical plane model based on the segmentation method are proposed in this paper. Two methods are compared with an arbitrary shaped power/ground plane. Furthermore, design considerations for the complete power distribution network structure are discussed to ensure the maximum value of the PDN impedance is low enough across the desired frequency range and to guide decoupling capacitor selection.

• 대한전기학회논문지:전력기술부문A
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• 제54권1호
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• pp.43-50
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• 2005

The presence of transmission congestion may reduce the market size and split the bulk power system into smaller systems. Consequently, this can be a key factor to the increase in market price. This paper analyzes the effect of exercising local market power on the market price, and derives a range of indices which quantify the degree and incentive of local market power through statistical analysis in an electricity market with uniform pricing scheme. The applicability and effectiveness of the derived indices on competitive electricity markets are demonstrated on the Korea electricity market.

• Journal of Electrical Engineering and Technology
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• 제4권1호
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• pp.35-42
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• 2009

When two adjacent AC systems operate at different frequency such as 50Hz and 60Hz, as in the case of ROK and Russia, the only way to practically obtain the advantages of power system interconnection is to use HVDC connection. In this paper, application of the VSC-HVDC transmission for power system interconnection between Russia and ROK is evaluated through the PSCAD/EMTDC modeling and analysis. The simulation results show the feasibility of proposed system for cross border power system interconnection.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1659-1663
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• 1991

A new control design methodology is presented here which is based on a nonlinear time-series reference model. It is indicated by highly nonlinear simulations that such designs successfully stabilize troublesome aircraft maneuvers undergoing large changes in angle of attack as well as large electric power transients due to line faults. In both applications, the nonlinear controller was significantly better than the corresponding linear adaptive controller. For the electric power network, a flexible a.c. transmission system (FACTS) with series capacitor power feedback control is studied. A bilinear auto-regressive moving average (BARMA) reference model is identified from system data and the feedback control manipulated according to a desired reference state. The control is optimized according to a predictive one-step quadratic performance index (J). A similar algorithm is derived for control of rapid changes in aircraft angle of attack over a normally unstable flight regime. In the latter case, however, a generalization of a bilinear time-series model reference includes quadratic and cubic terms in angle of attack. These applications are typical of the numerous plants for which nonlinear adaptive control has the potential to provide significant performance improvements. For aircraft control, significant maneuverability gains can provide safer transportation under large windshear disturbances as well as tactical advantages. For FACTS, there is the potential for significant increase in admissible electric power transmission over available transmission lines along with energy conservation. Electric power systems are inherently nonlinear for significant transient variations from synchronism such as may result for large fault disturbances. In such cases, traditional linear controllers may not stabilize the swing (in rotor angle) without inefficient energy wasting strategies to shed loads, etc. Fortunately, the advent of power electronics (e.g., high-speed thyristors) admits the possibility of adaptive control by means of FACTS. Line admittance manipulation seems to be an effective means to achieve stabilization and high efficiency for such FACTS. This results in parametric (or multiplicative) control of a highly nonlinear plant.

• 한국정밀공학회지
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• 제12권7호
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• pp.66-73
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• 1995

Rating systems of bevel gears(straight, spiral, and zerol bevel gears) which are commonly used as power transmission devices for non-papallel axes are developed on the personal computer, which analyze and/or evaluate the gear design and the service performance at the point of view of strength and durability. The typical considerations of the ratings are the bending strength, the surface durability, and the scoring resistance. The ratings are carried out using the reliable standards of AGMA & Gleason Works. Therefore, the system is built so that the variables or factors considered differently in those standards and the strength, dura- bility, and scoring partially in Gleason are appraised seperately by each method, and a series of the estimation processes is integrated into the system so as to compare each result. The developed rating systems can be used in the initial stage of gear design process, and also a better design can be performed by the evaluation of the initial design at the view point of gear strength and durability. Additionally, it is useful for the trouble-shooting of bevel gear system and to the purpose of introducing the methods for maintaining design strength in service, with appraising the gear strength after design or with appraising the influencing factor as a whole. Therefore, this rating systems can help the aim of design automation of bevel gears.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.156-158
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• 2000

As we are industrialized lately, power capacity is increased in the city urban areas. So the application of underground transmission line is largely expended. In this paper, we analysis the induction voltage on the sheath of 1,200[$mm^2$] OF underground cable being used 154kV underground transmission line. If the current on the cable conductor is 300[A], circulation current is induced the maximum 100[A] on the cable sheath.

• 한국통신학회논문지
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• 제32권3A호
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• pp.271-280
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• 2007

본 논문에서는 동일 채널 간섭이 존재하는 셀룰러 환경에서 OFDM 통신 시스템들이 각기 목표로 하는 전송속도를 달성하기 위한 송신 전력 조절 방안을 제시하였다. 일반적으로 다중 반송파 시스템에 대한 최적 또는 준 최적 송신 전력 할당 방안은 주파수 대역별로 채널 상태에 따라 송신 전력을 조절하는 형태인 것으로 알려져 있으며, 이는 WF(waterfilling)이나 IWF(iterative waterfilling) 형태로 발표된 바 있다. 하지만 반송파별로 송신 전력을 달리하는 방식을 구현하기 위해서는 각 대역별 채널 상태와 관련된 정보를 별도의 궤환 링크(feedback link)를 통해 수신기에서 송신기로 전송해야 한다. 만약 채널 상태가 빠르게 변하거나 반송파의 개수가 크다면 이로 인한 부담이 상당할 수가 있다. 이에 본 논문에서는 이런 부담을 줄이기 위한 방안으로 부반송파마다 동일한 송신 전력을 사용하는 방식에 대한 전력 조절 알고리듬을 제시한다. 그리고 제안한 알고리듬이 수렴한다는 것을 증명하고, 기존의 IWF 방식과 복잡도를 비교하며, 컴퓨터 실험을 통해 수렴 특성을 살펴보고자 한다.

• 한국ITS학회 논문지
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• 제9권6호
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• pp.105-112
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• 2010

최근, 무선통신 시스템의 발전으로 다중대역을 위해 광대역에서 동작하는 회로들이 소개되었다. 하지만 광대역에서 동작하는 회로들은 필연적으로 크기가 증가하는 단점이 있다. 이중대역에서 동작하는 회로는 원하는 두 주파수에서만 동작하기 때문에 불필요한 소자들의 감소로 소형화가 가능하다. Wilkinson 전력 분배기는 무선통신시스템에서 전력분배를 위해 일반적으로 사용되는 소자로써, 이 또한 최근 이중대역이 요구되어지고 있다. 본 논문에서는 IEEE 802.11n WLAN을 위하여 2.45GHz와 5.2GHz에서 동작하는 소형화된 이중대역 Wilkinson 전력 분배기를 제안한다. 제안된 Wilkinson 전력 분배기는 일반적인 Wilkinson 전력분배기의 ${\lambda}$/4파장 부분을 ${\pi}$-형 병렬 스터브라인으로, 전기적 길이와 임피던스를 변환하여 수행되었다.

• Journal of Communications and Networks
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• 제18권3호
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• pp.375-386
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• 2016

Most existing studies on broadcast services in orthogonal frequency division multiplexing (OFDM) systems have focused on how to allocate the transmission power to the subcarriers. However, because a broadcasting system must guarantee quality of service to all users, the performance of the broadcast service dominantly depends on the channel state of the user who has the lowest received signal-to-noise ratio among users. To reduce the effect of the worst user on the system performance, we propose a joint delivery scheme of unicast and broadcast transmissions in OFDM systems with broadcast and unicast best-effort users. In the proposed joint delivery scheme, the BS delivers the broadcast information using both the broadcast and unicast subcarriers at the same time in order to improve the performance of the broadcast service. The object of the proposed scheme is to minimize the outage probability of the broadcast service while maximizing the sum-rate of best-effort users. For the proposed joint delivery scheme, we develop an adaptive power and subcarrier allocation algorithm under the constraint of total transmission power. This paper shows that the optimal power allocation over each subcarrier in the proposed scheme has a multi-level water filling form. Because the power allocation and the subcarrier assignment problems should be jointly solved, we develop an iterative algorithm to find the optimal solution. Numerical results show that the proposed joint delivery scheme with adaptive power and subcarrier allocation outperforms the conventional scheme in terms of the outage probability of the broadcast service and the sum-rate of best-effort users.

• 전기학회논문지P
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• 제61권4호
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• pp.228-233
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• 2012

In power system, substation facilities have become too complex and larger according to an extended power system. Also, customers require the high quality of electrical power system. However, some facilities become old and often break down unexpectedly. The unexpected failure may cause a break in power system and loss of profits. Therefore it is important to prevent abrupt faults by monitoring the condition of power systems. Among the various power facilities, power transformers play an important role in the transmission and distribution systems. In this research, we develop intelligent diagnosis technique for monitoring of power transformer by FCM(Fuzzy c-means) and ELM(Extreme Learning Machine). The proposed technique make it possible to diagnosis the faults occurred in transformer. To demonstrate the validity of proposed method, various experiments are performed and their results are presented.