• 조명전기설비학회논문지
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• 제23권10호
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• pp.29-35
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• 2009

본 논문에서는 두 가지 전압을 이용하여 직류 전력선을 이용한 양방향 다중직렬통신 드라이버의 구현과 이를 위한 소형화 회로 설계에 대하여 다룬다. 다중접속통신은 호스트에 고유의 ID를 갖는 여러 개의 클라이언트와 패킷에 의한 데이터 전송을 행한다. 양방향 통신을 위하여 호스트에서 데이터 1/0이 전송될 경우, 각 경우에 24[V]/12[V]전원을 선택하며 클라이언트가 데이터를 전송할 때, 호스트는 통신선로의 전압을 감지하여 전송하는 데이터에 따라, 24[V]/12[V]전원을 선택한다. 이러한 기능을 구현하는 소형 드라이버 회로를 설계, 제작하여 호스트와 클라이언트의 직렬 통신 포트에 접속하였으며, 하나의 호스트와 여러 개의 클라이언트로 네트워크을 구현하고 실험에 의하여 직류 전력선을 이용한 양방향 직렬통신의 기능을 확인하였다.

• 전기학회논문지P
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• 제60권4호
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• pp.206-213
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• 2011

Line sleeves, which used to connect ACSR cables when transmission lines were constructing, sometimes cause power transmission failure due to deterioration and corrosion. Therefore, power transmission line should be inspected regularly to prevent national disaster. Current inspection tool detects insertion length of transmission line on line sleeves, the inspection tool includes enormous error by operator. Moreover, the system is not controlled remotely, negligent accident would be caused while inspecting. To deal with those problems, KEPCO reviewed several ways to inspect line sleeves and proposes new method to inspect line sleeve by measuring magnetic flex which penetrate junction of steel and aluminum sleeve. The developed inspection tool is reliable enough to detect eccentric sleeves. Also, the developed inspection device was applied on actual transmission line and verified its effectiveness.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.276-278
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• 2000

In KwangYang steel works power system operation, the ON-LINE application of power system diagnosis technology is indispensable to not only power quality, but also stable operation and economical generation. In cases of stability constraint violation. stable power system operation is obstructed. Steel works power system is consist of 154kV transmission lines, and 345, 154, 22, and 6.6[KV] distributed lines, 5 numbers of substation, 17 units of generators. For this power system operation. loadflow program is developed. Database is tied with Windows GUI application, is designed, and is interfaced with this program. This program put up with loadflow solution of assembled MMI power system, and planed to diagnose of overloads or to imitate entrance, and isolation of equipment.

• 정보통신설비학회논문지
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• 제10권2호
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• pp.74-79
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• 2011

The goal of this research is to reduce dynamic and static power consumption for a low power cache system. The proposed cache can achieve a low power consumption by using a drowsy and a way prediction mechanism. For reducing the static power, the drowsy technique is used at 4-way set associative cache. And for reducing the dynamic energy, one among four ways is selectively accessed on the basis of information in the Way-Line Prediction Unit (WLPU). This prediction mechanism does not introduce any additional delay though prediction misses are occurred. The WLPU can effectively reduce the performance overhead of the conventional drowsy caching by waking only a drowsy cache line and one way in advance. Our results show that the proposed cache can reduce the power consumption by about 40% compared with the 4-way drowsy cache.

• KIEE International Transactions on Power Engineering
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• 제4A권2호
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• pp.91-99
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• 2004

This paper illustrates a tie line constrained equivalent assisting generator (TEA G) model considering forced outage rates of transmission systems for reliability evaluation of interconnected power systems. Interconnections between power systems can provide improved levels of reliability. It is expected that the TEAG model developed in this paper will prove useful in the solution to problems related to the effect of transmission system uncertainties in the reliability evaluation of interconnected power systems. The characteristics and concept of this TEAG considering transmission systems are described in detail by sample studies on a simple test system.

• 대한전기학회논문지
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• 제36권9호
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• pp.609-615
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• 1987

The optimal operation of power system is developed by alternately using real power dispatch and reactive power dispatch problem. The real power system scheduling process is formulated as an optimization problem with linear inequality constraints. A.C. loadflow method is used for the problem solution and line losses are considered. The constraints under consideration are generator power limits, load scehdling limits and line capacity limits. In solving the objective function the Dual Relaxation method is adopted. Tests indicate that the method is practical for real time application. The reactive power control problem uses the Dual Simplex Relaxation method as in the real scheduling case. Insted of minimizing the cost of power system, the objective is selected as to determine the highest possible voltage schedule. The constraints under consideration are the voltage limits at each node and the possibilities of supply or absobtion of reactive energy by generator units and the compensation facilities. Tests indicate that the method is practical for real time applications. The overall optimization methods developed in this paper proved to obtained fine results in minimizing object function compared with the method without using voltage control. And the overall voltage profiles were also improved.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.1864-1872
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• 2014

Maloperation of protective relays is one of the major causes for cascading tripping in WANS. Another line trip followed by a previous line trip may occur due to overloading of the line, because of the load redistribution or unwanted trip of a backup relay due to change in the flow of fault current. Evaluation of each line is required by considering both of these effects. A new index named Line Security Index (LSI) is proposed in this paper which combines both Vulnerability Index (VI) and Protectability Index (PI) to completely evaluate the security of individual lines and their importance in the power grid. Computer simulations have been performed on the Korean power grid data to establish the feasibility of the proposed idea.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.53-54
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• 2005

This paper describes that send some signal from encoder attached to crankshaft of marine-engine to measuring instrument using power line modem(PLM) and display cylinder pressure, rpm and etc. on LCD. Conventional method that sends signal along the long signal line has some inconvenience from too long signal line length caused by huge volume of ship's engine. Power line modem can have short signal line from outlets to measuring instrument. Because it use exist power line for send signals, so it have low installation cost and could have good merits in job sites. Through this experiment, pressure in cylinder, engine rpm and etc. signals through PLM are well recognized at measuring instrument.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.903-906
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• 1997

When large capacity generation stations that consist of several large units tend to pull out of step from main power system, stabilizing control scheme as emergency control for preventing loss of synchronism of the whole stations with the remaining system is devided into two steps that the first step is to perform on-line prediction for out-of-step and the next step is on-line calculation of the amount of generation shedding for the rest of generators to be in step when out of step is expected. This paper presents on-line prediction scheme for out-of-step based on P-$\delta$ curve estimation using real-time measurement and on-line calculation of generation shedding. The proposed stabilizing scheme was applied to case study of real power system and the results obtained by the method compare well with the results by simulation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.121-124
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• 2001

On-line prediction model which calculate roll force, roll power and forward slip of continuous hot strip rolling was built based on the results of plane strait rigid-viscoplastic finite element process model. Using the integrated FE process model, a series of finite element simulation was conducted over the process variables, and the influence of various process conditions on non-dimensional parameters was inspected. The prediction accuracy of the proposed on-line model under front and back tension is examined through comparison with predictions from a finite element process model over the various process conditions. In addition, we examined the validity of the on-line prediction model through comparison with roll force of experiment in hot rolling.