• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.5
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• pp.21-29
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• 1992

This paper proposes a new MAC propocol for high-speed MAN. The proposed protocol is based on the P$_1$-persistent tranmission scheme and each node calculates the transmission probability periodically by using delay information(DI). A window mechanism for the calculation of message delay in each node is proposed to improve the adaptability of the proposed protocol to traffic changes. The capactiy of the proposed protocol is analyzed. The simulation results show that the proposed protocol gives fair message delay under heavy load conditions and, when the transmission speed or distance is increased, the message delay variation of the proposed protocol is less than that of IEEE 802.6 DQDB.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.234-240
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• 2004

Now that the e-commerce users are explosively increasing, there is always followed by a sharp increase in load from the e-commerce system and the heavy traffic on the network, where leads to the delayed service for the client's request. The natural consequences contain decreasing customer satisfaction and weakening the business's competitive position in markets. Therefore, we'll need to study the e-commerce system in due consideration of the operational efficiency and response speed. This study includes a design of e-commerce system, with a hierarchical structure based on the local server, which has the capability of caching necessary to distribute the system load, makes a proposal concerning a split web-cache algorithm devoted to the local web server to finally give an analysis of the performance through the appropriate trial.

• Journal of the Korean Mathematical Society
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• v.40 no.1
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• pp.87-107
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• 2003

In this paper, we consider a discrete time queueing system fed by a superposition of an ON and OFF source with heavy tail ON periods and geometric OFF periods and a D-BMAP (Discrete Batch Markovian Arrival Process). We study the tail behavior of the queue length distribution and both infinite and finite buffer systems are considered. In the infinite buffer case, we show that the asymptotic tail behavior of the queue length of the system is equivalent to that of the same queueing system with the D-BMAP being replaced by a batch renewal process. In the finite buffer case (of buffer size K), we derive upper and lower bounds of the asymptotic behavior of the loss probability as $K\;\longrightarrow\;\infty$.

• Journal of the Korean Mathematical Society
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• v.32 no.2
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• pp.211-236
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• 1995

The purpose of this paper is to provide a transient diffusion approximation of queue size distribution for M/G/m/N system. The M/G/m/N system can be expressed as follows. The interarrival times of customers are exponential and the service times of customers have general distribution. The system can hold at most a total of N customers (including the customers in service) and any further arriving customers will be refused entry to the system and will depart immediately without service. The queueing system with finite capacity is more practical model than queueing system with infinite capacity. For example, in the design of a computer system one of the important problems is how much capacity is required for a buffer memory. It its capacity is too little, then overflow of customers (jobs) occurs frequently in heavy traffic and the performance of system deteriorates rapidly. On the other hand, if its capacity is too large, then most buffer memories remain unused.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.5
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• pp.637-642
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• 2014

Military communications have limited resources such as poor bandwidth and insufficient link capacity. Numerous hosts in conventional IP networks, including the Tactical Information Communication Network (TICN), the tactical communication system of the Army, focus heavy traffic on a single server via end-to-end connections and in which data delivery latency is caused by exchanging routing information. Content-Centric Networking (CCN), one framework of Information-Centric Networking (ICN), is a novel Internet paradigm in which data can be accessed by the name of the content instead of the location information. This paper provides content caching strategies for applying CCN to military tactical IP networks based on TICN environment.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.309-310
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• 2001

휘발성 유기화합물(Volatile Organic Compounds; 이하 VOCs라 함)은 도시대기 중 광화학 스모그의 기인자인 동시에 발암성 혹은 돌연변이원성인 인체에 유해한 물질들이 많으므로 최근 들어 관심의 대상이 되고 있다. 이러한 VOCs의 발생원은 복잡ㆍ다양하지만 인위적인 주요 배출원은 유기용제와 자동차이다. 본 연구에서는 자동차 배출가스의 영향을 많이 밭고 있는 도시교통밀집지역의 VOCs의 출현양상 및 분포특성을 파악하고 도시교통밀집지역과 교통량의 영향을 비교적 적게 받는 교외 지역에서의 VOCs 분포특성을 비교해 보고자 한다. (중략)

• Journal of Environmental Impact Assessment
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• v.7 no.2
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• pp.127-133
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• 1998

The atmospheric deposition flux was measured with dustfall from July of 1997 to July of 1998 at nine sampling sites located in Tae-an peninsula to examine the seasonal variations. The results showed that the average dry deposition was higher in spring than the other seasons. Thus, it is considered that yellow sand is one major source of the additional deposition flux in spring. There also appeared the higher measurement of deposition at the sites nearby road (like Hagampo, Bangali and Sinduri) in summer, and it is assumed that the heavy traffic caused by summer visitors was the main factor of that. For more accurate study, the qualitiative analysis should be taken on the deposited materials.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.996-1002
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• 2006

USB(Universal Serial Bus) is one of the most popular communication interfaces. When USB is used in an extended range, especially configurating In-home network by connecting multiple digital devices each other, USB interface uses the bandwidth in the way of TDM (Time Division Multiplexing) so that the bottleneck of bus bandwidth can be brought. In this paper, the more effective usage of bus bandwidth to overcome this situation is introduced.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.202-214
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• 2003

The central challenge in the design of ad-hoc networks is the development of dynamic routing protocol that efficiently finds route between mobile nodes. Several routing protocols such as DSR, AODV and DSDV have been proposed in the literature to facilitate communication in such dynamically changing network topology. In this paper, a Node Transition Probability (NTP) based routing algorithm, which determines stable routes using the received power from all other neighboring nodes is proposed. NTP based routing algorithm is designed and implemented using Global Mobile Simulator (GloMoSim), a scalable network simulator. The performance of this routing algorithm is studied for various mobility models and throughput, control overhead, average end-to-end delay, and percentage of packet dropped are compared with the existing routing protocols. This algorithm shows acceptable performance under all mobility conditions. The results show that this algorithm maximizes the bandwidth utilization during heavy traffic with lesser overhead.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.55-65
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• 2002

Emission from road traffic is one of the major sources of air pollution, and provides some undesirable effects on the atmspheric environment and human health. In the city of Seoul, the higher portion of diesel vehicles runs compared with that of other countries. Emission from the diesel vehicles is much higher than that of other vehicles. In this study, the driving pattern of city-bus in Seoul is investigated through on-road vehicle test and compared with the test modes of other countries in order to examine appropriateness of the present test mode that is taken in our country.