• 한국정보처리학회논문지
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• 제6권11호
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• pp.3097-3107
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• 1999

Recently many studies have been done on the Random Early Detection(RED) algorithm as an active queue management and congestion avoidance scheme in the Internet. In this paper we first overview the characteristics of RED and the modified RED algorithms in order to understand the current status of these studies. Then we analyze the RED dynamics by investigating how RED parameters affect router queue behavior. We show the cases when RED fails since it cannot react to queue state changes aggressively due to the deterministic use of its parameters. Based on the RED parameter analysis, we propose a self-adaptive algorithm to cope with this RED weakness. In this algorithm we make two parameters be adjusted themselves depending on the queue states. One parameter is the maximum probability to drop or mark the packet at the congestion state. This parameter can be adjusted to react the long burst of traffic, consequently reducing the congestion disaster. The other parameter is the queue weight which is also adjusted aggressively in order for the average queue size to catch up with the current queue size when the queue moves from the congestion state to the stable state.

• Journal of information and communication convergence engineering
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• 제9권5호
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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.

• 정보처리학회논문지A
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• 제13A권7호
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• pp.573-580
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• 2006

기존의 가장 널리 쓰이는 전송계층 프로토콜인 TCP는 패킷 손실의 원인이 망의 혼잡 때문이라는 가정 하에 설계된 프로토콜로서 유선망과 고정 호스트로 이루어진 전통적인 네트워크에는 적합하지만 페이딩, 잡음, 간섭 등의 전송 에러가 발생하는 무선 환경에서는 전송 프로토콜로서 적용하기에 비효율적이다. 이것은 무선망에서의 비트 에러에 의한 패킷손실 역시 혼잡으로 간주하여 불필요한 전송 제어가 발생하기 때문이다. 본 논문에서는 무선 TCP 패킷의 전송성능을 향상시키기 위하여 연속적인 패킷 손실에 대한 제어와 TCP 윈도우 제어를 하여 불필요한 혼잡제어 알고리즘을 수행하지 않게 하는 개선된 SNOOP 프로토콜을 제안하였고 개선된 모듈의 성능을 모의실험을 통하여 확인하였다.

• 전기학회논문지
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• 제60권2호
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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.

• 한국주거학회논문집
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• 제21권4호
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• pp.11-22
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• 2010

In the urban area where rapid suburbanization trend continues, the role of mixed use building is controversial. It is argued that the mixed use building is an effective tool to recover residential function of urban core(urban regeneration). It is also argued that the building is a cause of serious urban problems, such as congestion, public service shortages. The fundamental purpose of this study is to examine the role of mixed use building in terms of urban growth management in Seoul. For this purpose, data of mixed use building from 1981 to 2007 are collected and analysed. The results show that most of mixed use buildings are located in either sub-centers or population losing areas, rather than traditional urban core. Therefore, it is hard to accept that the two controversial arguments. The mixed use building noncore areas in most cases. However, it dose help to increase population inflow in non-core areas. it is difficult to accept the public service assertion which states that super-high rise mixed use building causes public service congestion, because the building is built in population losing or demand decreasing area. Based on these findings this study suggests some policy alternatives such as urban service boundary or concurrency program to management urban growth.

• 한국인터넷방송통신학회논문지
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• 제16권1호
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• pp.129-137
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• 2016

전송계층 프로토콜처럼 전송제어 프로토콜은 안정적인 데이터 전송 서비스를 제공한다. 다양한 네트워크에서 TCP의 성능을 저해하는 일부 심각한 문제가 있다. TCP 네트워크 환경에서 중요한 문제는 빠른 전송 속도로 인해 또는 동시에 네트워크로 접속하는 다수의 새로운 접속으로 인하여 발생하는 혼잡이다. 그러므로 라우터에서 큐의 크기는 패킷 하락에 기인하여 증가한다. 손실된 패킷의 재전송과 감소된 처리량은 많은 비용을 발생시킨다. RED처럼 AQM과 ECN은 패킷 하락 보다는 패킷 마킹에 사용된다. IP 패킷 헤더에서 ECN 비트는 불필요한 패킷 하락을 피하기 위한 혼잡 표시로 추가할 수 있다. 제안하는 ECN과 AQM 메커니즘은 NS2 시뮬레이터의 도움으로 구현할 수 있으며, 그 성능은 다른 TCP 변종에서 테스트할 수 있다.

• 대한안전경영과학회지
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• 제14권1호
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• pp.43-51
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• 2012

This study was carried out to observe the impacts of a mouse's inhalation of toxic gas SO2 generated from combustion on its organs by different concentrations. As for research methods: First, after concentrations of SO2 generation from combustion had been set to three: low (10.4 ppm), middle (24.9 ppm) and high (122 ppm) through Gas Toxicity Testing Method (KS F 2271) and SO2 combustion gas was exposed to eight mice in each concentration. Five mice that were able to move based on LD50, a criterion, which sets the down time of a mouse's average behaviors to over 9 minutes, were randomly selected in each concentration, and they were set up as the subjects of the study on toxicity bio-markers. Second, tissues were taken from heart, liver, lungs, spleen and the thymus gland of the mice selected in each concentration and a pathological examination of them was carried out. As a result, microvascular congestion appeared in the heart, and cell necrosis, cortex congestion and tubule medulla congestion, etc. in each concentration were observed in addition to vascular congestion in liver, lungs, spleen and the thymus gland. Also, it was found that the higher the concentrations of SO2 exposure is, the greater, the changes in the organs get. Through this study, SO2 of various toxic gases generated from fire turned out to affect the tissues of each organ of a mouse, it is expected that the toxic gases may greatly affect human body in case of actual fire, and this study is evaluated as having a significance as a basic data on inhalation toxicity assessment of toxic substances generated in combustion.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1987년도 추계학술발표회 발표논문초록집; 중소기업협동조합중앙회, 서울; 31 Oct. 1987
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• pp.35-35
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• 1987

Consider a job shop that is modelled as an open queueing network of the Jackson(l957) type. All work stations in the shop have the same number of parallel servers. Two problems are studied : the loading of stations and the assignment of servers, which are represented by loading and assingment vectors, respectively. Ma jorization and arrangement orderings are established to order, respectively, the loading and the assignment vectors. It is shown that reducing the loading vector under ma jorizat ion or increasing the assignment vector under arrangement ordering will reduce the congestion in the shop in terms of reducing the total number of jobs(in the sense of likelihood ratio ordering), the maximum queue length(in the sense of stochastic ordering), and the queue-length vector( in the sense of stochastic majorization). The results can be used to supprot production planning in certain job shops, and to aid the desing of storage capacity. (OPEN QUEUEING NETWORK; WJORIZATION; ARRANGEMENT ORDERINC; LIKELIHOOD RATIO ORDERINC; STOCHASTIC ORDERING)

• Journal of Electrical Engineering and Technology
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• 제1권1호
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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.

• 한국경영과학회지
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• 제32권3호
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• pp.63-80
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• 2007

This study is a generalization of 'stable dynamics' recently suggested by Nesterov and de Palma[29]. Stable dynamics is a new model which describes and provides a stable state of congestion in urban transportation networks. In comparison with user equilibrium model that is common in analyzing transportation networks, stable dynamics requires few parameters and is coincident with intuitions and observations on the congestion. Therefore it is expected to be an useful analysis tool for transportation planners. An equilibrium in stable dynamics needs only maximum flow in each arc and Wardrop[33] Principle. In this study, we generalize the stable dynamics into the model with multiple traffic classes. We classify the traffic into the types of vehicle such as cars, buses and trucks. Driving behaviors classified by age, sex and income-level can also be classes. We develop an equilibrium with multiple traffic classes. We can find the equilibrium by solving the well-known network problem, multicommodity minimum cost network flow problem.