• Annual Conference of KIPS
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• 2001.04a
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• pp.531-534
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• 2001

라우터나 스위치 같은 네트워크상의 접근 포인트에서 트래픽들에 대한 불공정 큐잉은 서비스의 성능을 저하시킬 뿐만 아니라 불필요한 병목을 일으킬 우려가 많기 때문에 트래픽들에 대한 공정한 패킷 스케줄링 기법들이 많이 연구되고 있다[2]. 그 중에서 서비스 할당량 SQ(Service Quantum)와 결손 계측자 DC(Deficit Counter)를 사용하는 DRR 기법은 다른 것들에 비해 작업 복잡도가 낮고 보다 정확한 공정성을 보장하는 패킷 스케줄링 기법이다. 그러나 이 기법은 TCP 프로토콜의 재전송 타이머에 의해 검출된 전송이 실패된 패킷을 고려하지 않고 있다. 본 논문에서는 TCP 프로토콜의 재전송 타이머에 의해 검출된 전송이 실패된 TCP 패킷을 관리하기 위한 추가적인 큐를 두어 기존의 DRR 보다 정확한 공정성을 보장하는 기법을 제안한다.

• Journal of the Korea Society of Computer and Information
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• v.6 no.4
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• pp.138-145
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• 2001

In this paper, we propose fuzzy closed BCMP queueing network model for the performance evaluation of distributed processing system. Which has the ambiguous service requirements of job to servers and service rates of server according to network environments. This model can derive the measures for system Performances using fuzzy mean value analysis which can process the fuzzy factors. Computer simulation has been performed for verifying the effectiveness of derived equations of performance evaluation according to service requirements of job and the numbers of clients.

• Annual Conference of KIPS
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• 2009.04a
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• pp.1045-1046
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• 2009

본 논문에서는 이산 이벤트 시뮬레이터인 SMPL을 이용하여 노변 네트워크에서의 데이터 처리에 따르는 데이터 캐쉬 성능분석기를 구현한다. 구현된 성능분석기는 SMPL의 요청 도착과 서비스 사건 처리를 기본 골격으로 하여 실제 차량의 궤적 데이터에 기반한 데이터 요청 생성부와 큐잉 정책과 캐쉬 정책을 선택할 수 있는 정책 처리부 등으로 구성된다. 이 분석기는 서비스율, 해당 정책, 캐쉬의 크기 등의 수행인자를 설정하여 이에 따르는 큐 길이의 분포, 캐쉬의 히트율, 요청 처리시간의 분포 등을 측정할 수 있도록 한다. 추정된 성능 요소를 기반으로 노변 네트워크에 기반한 차량 텔레매틱스 시스템에서 RSU(RoadSide Unit)의 배치, 성능 요구사항 분석, 새로운 큐잉 정책과 캐쉬 정책의 설계 등 다양한 응용이 가능하다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1785-1796
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• 1993

Thanks to the data processing facilities of modern digital computers, the performances of radar has been promoted greatly as one of the main components of command and control systems along with the computer communications. In this study, radar data integrating and processing systems were designed for the data processing of various information from many kinds of radar in a single data processing system. The performance of the data integrating system was analyzed by applying queueing theory. A radar data integrating network was designed for synchronous relational operations among the information processing systems and the transmission characteristics were also analysed by specific models for each system. The designed data integrating systems can be divided into a simplex type and a distributed multiplex type.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.122-131
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• 2000

In this paper, we propose a cell scheduling algorithm for input queueing ATM switch. The input queueing architecture is attractive for building an ultra-high speed ATM (Asynchronous Transfer Mode) switch. We proposea WMUCS (Weighted Matrix Unit Cell Scheduler) based on the MUCS which resolves HOL blocking and outputport contention. The MUCS algorithm selects an optimal set of entries as winning cells from traffic matrix (weightmatrix). Our WMUCS differs from the MUCS in generating weight matrices. This change solves the starvationproblem and it reduces the cell loss variance. The performance of the proposed algorithm is evaluated by thesimulation program written in C++. The simulation results show that the maximum throughput, the average celldelay, and the cell loss rate are significantly improved. We can see that the performance of WMUCS is excellentand the cost-effective implementation of the ATM switch using proposed cell scheduling algorithm.

• 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.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3185-3193
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• 1998

ATM망은 망 내부의 큐잉 랜덤 지연에 의한 CDV의 발생으로 클럭복원의 문제를 안고 있다. 큐잉에 의한 지연은 여러 가지 파라메터에 의해 좌우되며 특히 망의 부하와 트래픽이 전송되는 교환기의 수에 의해 크게 좌우된다. CBR 트래픽의 경우 이를 해결하기 위해 SAR 헤더에 송신부의 클럭 정보를 담아 보내고 수신부에서는 이 정보를 바탕으로 송신부의 클럭을 복원하는 SRTS 기법을 사용하고 있다. 그러나 실시간성을 요하는 VBR 트래픽은 CBR과는 달리 대역폭의 가변적인 성질을 가지고 있으며 그 변화가 다양하여 SRTS 기법을 그대로 적용하기 곤란하다. VBR의 경우에 CBR 전송을 위한 SRTS 기법을 그대로 적용하면 주파수의 가변성으로 인해 망 클럭 주파수에 비해 매우 낮은 주파수의 경우에는 사이클이 상대적으로 많아 정보의 정확성이 떨어지게 된다. 이를 방지하기 위해 서비스 클럭의 주파수가 낮은 경우에는 망 기준 주파수를 낮게 하므로써 정확성을 증가시킬 수 있다. 또한, VBR 트래픽의 경우 AAL1에서는 SRTS의 필요성이 강조되지 않으나 단지 CDV를 제거할 방법이 요구되어진다. 따라서 AAL1의 SRTS를 CDV의 측정을 위한 메카니즘으로 바꾸는 것이 필요하며, 각 기반으로하여 Wavelet 변환을 이용한 VBR 트래픽의 클럭 복원방식을 제안한다. 제안된 알고리즘은 ATM망에서 VBR 영상 서비스를 위한 AAL 계층에 이용이 가능하다. 시뮬레이션 결과는 wavelet 변환 블록에서 출력되는 계수 값을 선택하여 전송함으로써 VBR 트래픽의 보다 다양한 QoS를 만족시킬 수 있음을 보인다.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.7
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• pp.500-504
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• 2009

A reliability of software is a type of nonfunctional requirement. Traditionally, a validation of the reliability is processed at the integration phase in software development life cycle. However, it increases the cost and the risk for the development. In this paper, we propose reliability analysis method based on mathematical analytic model at the architecture design phase of the development process as follows. First, we propose the software modeling methodology for reliability analysis using Hierarchical combined Queueing Petri Nets(HQPN). Second, we derive the Markov Reward Model from the HQPN based model. We apply our approach to the video conference system to verify the usefulness of our approach. Our approach supports quantitative evaluation of the reliability.

• The KIPS Transactions:PartC
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• v.9C no.1
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• pp.21-30
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• 2002

Nowadays the fair queuing field is studied actively for solving the unfair queuing problem which degrades the service performance of various applications on network. Above all DRR is a scheme that has lower work complexity and can be implemented easily. It guarantees the fair service by serving each queue every round Service Quantum(SQ) that includes the service deficit of the previous round. But it increases the delay by the numbers of unnecessary resetting of SQ or round circulation for the service that have the packet size over maximum several kbyte. In this paper, We propose the method that sets SQ dynamically to minimize this problem and the method that minimizes the work complexity on processing of packet. The proposed scheme minimizes the delay on various applications in enterprise environment by setting SQ dynamically and processing the packet simply.

• 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.