• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.2014-2027
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• 1994

A queueing model with two input streams of different service priorities is studied. Specifically, IBP+BP/D/1 with head-of-line priority is analyzed. IBP and BP stand for Interrupted Bernoulli Process and Bernoulli Process respectively. The BP-stream customers have the higher service priority over the IBP-stream customers. An exact analysis of this priority queue is presented to derive the distributions of the state of the system at steady state, the waiting time distributions for each class of customers, and the interdeparture time distributions. The numerical results of the analysis are presented to show how the various parameters of the low and high priority arrival processes affect the performance of the system.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.39-47
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• 2000

This paper is to propose an efficient and reliable control procedure of Base Station Controller of mobile communication system for bulk input messages which was delivered instantaneously. We divided the input messages that are processed by the base station controller of the mobile communication system into two things ; they are messages related to call connection and o&m(operation and maintenance). In addition, we analyzed the properties of the input messages and then performed computer simulation on each input message by using M/M/1/K queueing model in term of the following viewpoints : the loss probability of input messages, the average queue length, the utilization of process controller(server),the average waiting time in queue. And we compared the performance of the two input messages in the overload controlling which was caused by the congested input messages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9B
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• pp.813-821
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• 2008

In recent year, several types of PON(Passive Optical Networks) have been adopted into the subscriber loops for the high speed subscriber lines to meet the needs of some applications based on the Internet and the rapid increase of the Internet users. GPON(Gigabit PON) is a typical access network technology of these PONs which adopt the DBA(Dynamic bandwidth Allocation) scheme in order to transmit upstream traffic efficiently. In this paper, we introduce the gated polling system with a two-stage queue in order to analyze the delay performance of the DBA scheme in a GPON. We use a continuous time queueing model for deriving the mean cycle time and for obtaining the mean packet delay. We give some numerical results to investigate the delay performance for the symmetric polling system with statistically identical stations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1320-1328
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• 2007

In recent year, the popularity of WLAN has generated much interests on improvement and performance analysis of the IEEE 802.11 protocol. In this paper, we analyze two medium access methods of the IEEE 802.11 MAC protocol by investigating the MAC layer packet service times when arrival packet sizes have a general probability distribution. We use the M/G/1/K queueing model to analyze the throughput and the delay performance of IEEE 802.11 MAC protocol in a wireless LAN. We compare the performances of Basic access method and RTS/CTS access method. We take some numerical examples for the system throughput and the queue dynamics including the mean packet delay and packet blocking probability.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.201-202
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• 2018

자동차 부품산업은 자동차산업의 후방산업으로 완성차 메이커 제조산업의 조립용인 중간재 산업으로 부품의 품질에 따라 완성차의 성능이 좌우된다. 자동차 산업구조상 완성차에 종속적인 사업구조로 부품사의 독자 성장이 어렵고 수익성이 완성차업체에 종속 된다. 자동차부품사의 대형화 및 생산공정 자동화 변화로 기존의 수직계열화된 부품 공급 관계에도 변화가 예상되며, 완성차업체는 통합적인 시스템 부품을 생산할 수 있는 글로벌 대형 부품업체에 의존하는 상황이 전개될 수도 있다. 이와 같은 위기와 변화를 극복하기 위해 본 연구에서는 산업구조분석을 자동차 부품산업에 적용하여 자동차부품산업의 경쟁력제고 전략을 도출하고자 한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.421-424
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• 2004

음성 중심의 기존 2G CDMA/PCS 시스템과 달리 CDMA2000 및 1xEV-DO와 같은 차세대 이동통신 시스템에서 패킷 데이터 서비스가 부각됨에 따라 효율적인 망의 설계 및 디멘져닝을 위해서는 무엇보다도 데이터 트래픽의 주요 특성인 버스트(Burst)와 자기유사성(Self-similarity)이 반영된 모델이 요구된다. 본 논문에서는 차세대 이동통신 시스템에서 자기유사 특성을 갖는 트래픽의 큐잉 성능을 시뮬레이션 하였고, 그 결과를 해석적 모델과 비교하였다. 또한 Crossover point의 변화와 출력링크의 변화도 분석하였다.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8
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• pp.2484-2496
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• 2000

High speed switches have been developing to interconnect a large number of nodes. It is important to analyze the switch performance under various conditions to satisfy the requirements. Queueing analysis, in general, has the intrinsic problem of large state space dimension and complex computation. In fact, The petri net is a graphical and mathematical model. It is suitable for various applications, in particular, manufacturing systems. It can deal with parallelism, concurrence, deadlock avoidance, and asynchronism. Currently it has been applied to the performance of computer networks and protocol verifications. This paper presents a framework for modeling and analyzing ATM switch using stochastic activity networks (SANs). In this paper, we provide the ATM switch model using SANs to extend easily and an approximate analysis method to apply A TM switch models, which significantly reduce the complexity of the model solution. Cell arrival process in output-buffered Queueing A TM switch with finite buffer is modeled as Markov Modulated Poisson Process (MMPP), which is able to accurately represent real traffic and capture the characteristics of bursty traffic. We analyze the performance of the switch in terms of cell-loss ratio (CLR), mean Queue length and mean delay time. We show that the SAN model is very useful in A TM switch model in that the gates have the capability of implementing of scheduling algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.963-966
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• 2003

IPv6-IPv4 변환시스템은 기존의 IPv4 네트워크와 신규 구축되는 IPv6 네트워크 간의 통신을 가능하게 하는 게이트웨이 기반 기술이다. 이러한 IPv6-IPv4 변환시스템에서는 네트워크 간의 모든 트래픽을 변환해야 하므로 높은 성능을 요구된다. 이에 본 연구에서는 이전 연구에서 구현된 게이트웨이 기반 IPv6-IPv4 변환시스템과 변환기의 성능분석에 적용될 수 있는 큐잉 모델을 제시하고 부과되는 트래픽에 따른 처리 성능을 산출하는 분석적인 방법을 제시하였다. IPv6-IPv4 변환시스템의 분석 모델의 경우, 도착간격은 지수분포를 따르고, 서비스시간은 M/M/l/K 모델 기반의 일반분포를 따른다. 또한 IPv6-IPv4 변환시스템의 변환기는 트래픽에 대한 변환 처리를 담당하는 핵심 모듈로서, 순차적인 단계로 이루어진다. 즉, 변환시스템의 변환기 자체의 분석 모델의 도착간격은 지수분포를 따르고, 서비스시간은 M/G/l/K 모델 기반의 일반분포를 따른다. 이렇게 제안된 모델에 대해 상세하게 설명하였으며, 이를 검증하기 위해서 모델을 적용하여 근사한 결과와 실제 측정 결과를 비교하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1582-1589
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• 2006

A lock mechanism is essential for synchronization on the multiprocessor systems. The conventional queuing lock has two bus traffics that are the initial and retry of the lock-read. %is paper proposes the new locking protocol, called WPV (Waiting Processor Variable) lock mechanism, which has only one lock-read bus traffic command. The WPV mechanism accesses the shared data in the initial lock-read phase that is held in the pipelined protocol until the shared data is transferred. The nv mechanism also uses the cache state lock mechanism to reduce the locking overhead and guarantees the FIFO lock operations in the multiple lock contentions. In this paper, we also derive the analytical model of WPV lock mechanism as well as conventional memory and cache queuing lock mechanisms. The simulation results on the WPV lock mechanism show that about 50% of access time is reduced comparing with the conventional queuing lock mechanism.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.10
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• pp.529-538
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• 2007

Fair Queueing algorithms based on Generalized Processor Sharing (GPS) not only guarantee sessions with service rate and delay, but also provide sessions with instantaneous fair sharing. This fair sharing distributes server capacity to currently backlogged sessions in proportion to their weights without regard to the amount of service that the sessions received in the past. From a long-term perspective, the instantaneous fair sharing leads to a different quality of service in terms of delay and bandwidth to sessions with the same weight depending on their traffic pattern. To minimize such long-term unfairness, we propose a delay-bandwidth normalization model that defines the concept of value of service (VoS) from the aspect of both delay and bandwidth. A model and a packet-by-packet scheduling algorithm are proposed to realize the VoS concept. Performance comparisons between the proposed algorithm and algorithms based on fair queueing and service curve show that the proposed algorithm provides better long-term fairness among sessions and that is more adaptive to dynamic traffic characteristics without compromising its service rate and delay guarantees.