• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.10
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• pp.610-615
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• 2003

With the growing competitive pressure from market participants, utilities, consumer and government, analyses of existing competitive electricity market become more important. The presence of congestion in the transmission system can significantly increase the potential of exercising market power. Since the congestion in the network depends on the several factors, the market power cannot be simply analyzed through the existing indices. This paper presents a systematic analysis on local market power under uniform pricing scheme and provides determining approach of the level of price cap as mitigation measure of the strategic market power.

• Journal of Electrical Engineering and Technology
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• v.1 no.1
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• pp.1-7
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• 2006

In an electricity market, the spot market is normally integrated with a forward or future market. The advantage of the forward market is to allow the market participants to deal in a part or the whole trading portfolio at a fix price in advance and to avoid risk associated to the uncertain price of the spot market. Japan has introduced a continuous auction base forward market from April 2005. This paper analyzes the Japanese forward market rules and operations, and introduces a new algorithm that may improve the efficiency of the market itself. The proposed algorithm enables us to give consideration to the specific characteristics of the power system and to integrate them in the auction mechanism. The benefits of the proposed algorithm are verified on an electronic simulation platform and the results described in this paper.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.399-406
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• 2000

There are sendee_based research and receiver_based research for dynamic adaptation to network congestion which arises from multicast video conference ; the former results in bandwidth waste of receivers who use high available bandwidth on account of average loss rate in transmission rate, the latter in short of the method that divides layers of available bandwidth of receivers dynamically. In order to do so, in this paper, we established two multicast groups divided into non-congestion status and congestion status according to receiver's network state, and implemented the bandwidth management algorithm which is designed for providing receivers with profitable qualities for available bandwidth by letting them choose each group dynamically in reference to loss rate. As a result, experiments proved that bandwidth waste problem was improved by receiver's dynamic choice according to loss rate.

• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.530-538
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• 2011

Performance of TCP can be severely degraded in Mobile IP-based wireless networks where packet losses not related to network congestion occur frequently during inter-subnetwork handoffs by user mobility. To solve such a problem in the networks using Mobile IP, the packet buffering method at a base station(BS) recovers those packets dropped during handoff by forwarding the buffered packets at the old BS to the mobile users. But, when the mobile user moves to a congested BS in a new foreign subnetwork, those buffered packets forwarded by the old BS are dropped and TCP transmission performance of a mobile user degrades severely. In this paper, we propose a Modified BLUE(MBLUE) buffer required at a BS to increase TCP throughput in Mobile IP-based networks. When a queue length exceed a threshold and congestion grows, MBLUE increases its packet drop probability. But, when a TCP connection is added at new BS by a handoff, the old BS marks the buffered packets. And new BS receives the marked packets without dropping. Simulation results show that MBLUE buffer reduces congestion during handoffs and increases TCP throughputs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.257-265
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• 2011

As the competitive market system has been introduced to the electrical power trade, the priority concern would be that the price of electrical power should be reasonable. It is because, when this rule is solid, we can avoid the distortion of competition and assure the greater efficiency in management. LMP(Locational Marginal Price) means marginal price at each bus. This components consist of energy, loss and congestion cost. At this point, the LMP result that is calculated by traditional model is changeable by the location of the slack and can not be used in bilateral Transaction. This paper proposed algorithm is proved its rationality and credibility by comparing the result of the simulation of virtual 6_bus system that is calculated by traditional method, and showed that the LMP components are changed according to the Transaction Strategy. Furthermore, It shows the effect of additional congestion cost on the transmission line that has bottle neck frequently by simulation.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.169-171
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• 2001

This paper presents a method fer evaluation nodal probabilistic congestion and reliability indices of transmission systems using Monte Carlo simulation methods. Quantitative evaluation of transmission system reliability is very important because successful operation of an electric power system. In the deregulated electricity market depends on transmission system reliability management Monte Carlo methods are often preferable, when complex operating conditions are involved and/or the number of sever events is relatively large. To evaluate the reliability of a real power system, Monte Carlo Methods will be more useful. The characteristics and effectiveness of this methodology are illustrated by the case study using a small test system.

• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.260-269
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• 2003

The traditional distributed object middleware platform is not suitable for the transmission of stream data, because RPC(Remote Procedure Call)-based message transmission have a great overhead. Therefore, the OMG(Object Management Group) proposes the AV(Audio and Video) stream reference model for streaming on the distributed object middleware platform. But, this reference model has not a detail of implementation. Particularly it also has not congestion control scheme for improvement of network efficiency on the real network environment. It is a very important and difficult technical issue to provide the stream transmission platform with advanced congestion control scheme. In this paper, we propose an architecture of a distributed stream transport platform and deal with the design and implementation concept of our proposed platform. Also, we present a mechanism to improve streaming utilization by SRTP(Smart RTP). SRTP is our proposed TCP-Friendly scheme.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.127-134
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• 2003

Ad Hoc Networks, autonomous distributed network using routing scheme, does not operate properly owing to multi flow service when network load increases at specific network node. In this paper, we suggest traffic management routing protocol in Ad Hoc Network to reduce network traffic congestion and distribute network load in data transmission. Through test results of proposed algorithm under NS(Network Simulator)simulator environments . we acquired reduced network load and increased data transmission rate.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.373-375
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• 2000

By DC load flow approximation, we analyzed marginal cost that is the important factor of price signal for network congestion management and expressed as a function of load. In network congestion, a large scale electric network is partitioned into subnetwork to provide a effetive price signal through zonal pricing. We propose a new network partition technique using marginal cost sensitivity with a variety of load consumption.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.822-824
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• 2005

This paper presents a scheme to solve the congestion problem using phase-shifting transformer(PST) in power systems. Available transfer capability(ATC) is an important indicator of the usable amount of transmission capacity accessible by several parties for commercial trading in power transaction activities. This paper deals with an application of optimization technique for ATC calculation. Sequential quadratic programming(SQP) is used to maximize power flow of tie line subject to security constraints such as voltage magnitude and real power flow. The proposed method is applied to 10 machines 39 buses model systems to show its effectiveness.