• 전자공학회논문지A
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• 제30A권3호
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• pp.67-75
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• 1993

In many practical applications of systolic array, it is common that the problem size(n) is larger than the array size(M). In this case, the problem has to be partitioned into block to fit into the array before it is processed. This paper presents a problem partition method for dynamic programming and 2-dimensional systolic array suitable for it. Designed array has two types of array configur-ation for processing the partitioned problem. The queue is designed for storing and recirculating the intermediate results in the correct location and time. The number of processing elements and queues required are M(3M+1)/2, 4M respectively. The total processing time is 2(M+1)+(n+10M+3)(n/M-1)(n/M-1)/6.

• Journal of applied mathematics & informatics
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• 제25권1_2호
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• pp.389-405
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• 2007

In this paper, we study a k-out-of-n system with single server who provides service to external customers also. The system consists of two parts:(i) a main queue consisting of customers (failed components of the k-out-of-n system) and (ii) a pool (of finite capacity M) of external customers together with an orbit for external customers who find the pool full. An external customer who finds the pool full on arrival, joins the orbit with probability ${\gamma}$ and with probability $1-{\gamma}$ leaves the system forever. An orbital customer, who finds the pool full, at an epoch of repeated attempt, returns to orbit with probability ${\delta}\;(<\;1)$ and with probability $1-{\delta}$ leaves the system forever. We compute the steady state system size probability. Several performance measures are computed, numerical illustrations are provided.

• 한국정보처리학회논문지
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• 제2권3호
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• pp.288-298
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• 1995

부하 평형은 과부하 사이트의 부하종 일부를 다른 사이트로 옮김으로써 분산 처리 시스템의 성능 개선을 꾀한다. 본 논문에서는 source-initiate와 server-initiate 방 식을 모두 지원하며 극단적인 예로서 m/m/1 대기행렬(부하 비평형)과 m/m/n 대기 행렬 (완전한 부하 평형)도 모델화 할 수 있는 부하 평형 방식을 제안하였다. 이 방식은 상 태 변수를 각 사이트에 복제하고 각 복사본의 일치성을 완화한다. 그리고 오래된 스케 줄러가 통신을 하지 않고도 부하 평형을 보장할 수 있는 충분조건을 요도하였다. 이 모델을 이용하면 부하 평형의 문제가 상태의 일관성을 유지하는 문제로 바뀌게 되며 기존의 비딩 알고리즘보다 통신량이 적어지게 된다. 이벤트 트레이싱 방법으로 모의 실험하였으며 2개의 극단적인 경우 및 비딩알고리즘과 비교하였다. 그 결과 평균 응답 시간과 통신량에 있어서 비딩알고리즘보다 각각 0-35%, 40-100%의 성능향상을 보였다. 마지막으로 각 시스템 피라미터의 영향을 분석하였다.

• 한국경영과학회지
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• 제29권3호
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• pp.1-7
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• 2004

We demonstrate in this paper that the level crossing technique can be applied to such a system that not only the state vector is two-dimensional but Its two components are heterogeneous. As an example system, we use the GI-G/c/K queue whose state vector consists of the number of customers in the system and the total unfinished work.

• Journal of applied mathematics & informatics
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• 제5권2호
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• pp.403-426
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• 1998

We present an algorithm to find an approximation for the stationary distribution for the general ergodic spatially-inhomogeneous block-partitioned upper Hessenberg form. Our approximation makes use of an associated upper block-Hessenberg matrix which is spa-tially homogeneous except for a finite number of blocks. We treat the MAP/G/1 retrial queue and the retrial queue with two types of customer as specific instances and give some numerical examples. The numerical results suggest that our method is superior to the ordinary finite-truncation method.

• 대한수학회논문집
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• 제11권2호
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• pp.481-493
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• 1996

We consider a retrial queue with two classes of customers where arrivals of class 1(resp. class 2) customers are MMPP and Poisson process, respectively. In the case taht arriving customers are blocked due to the channel being busy, the class 1 customers are queued in priority group and are served as soon as the channel is free, whereas the class 2 customers enter the retrial group in order to try service again after a random amount of time. We consider the following retrial rate control policy, which reduces their retrial rate as more customers join the retrial group; their retrial times are inversely proportional to the number of customers in the retrial group. We find the joint generating function of the numbers of custormers in the two groups by the supplementary variable method.

• East Asian mathematical journal
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• 제24권1호
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• pp.45-55
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• 2008

We consider an M/G/1 queue with $P^M_{\lambda}$-service policy, which is a two-stage service policy. The server starts to serve with rate 1 if a job arrives to the sever in idle state. If the workload of the system upcrosses $\lambda$, then the service rate is changed to M and this rate continues until the system is empty. It costs to change the service rate to M and maintaining the rate. When the expectation of the stationary workload is supposed to be less than a given value, we derive the optimal value of M.

• Journal of applied mathematics & informatics
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• 제5권1호
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• pp.1-12
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• 1998

We consider G/M/1 queues with multiple vacation disci-pline where at the end of every busy period the server stays idle in the system for a period of time called changeover time and then follows a vacation if there is no arrival during the changeover time. The vaca-tion time has a hyperexponential distribution. By using the methods of the shift operator and supplementary variable we explicitly obtain the queue length probabilities at arrival time points and arbitrary time points simultaneously.

• 대한산업공학회지
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• 제25권1호
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• pp.125-129
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• 1999

The Little's formula, $L={\lambda}W$, expresses a fundamental principle of queueing theory: Under very general conditions, the average queue length is equal to the product of the arrival rate and the average waiting time. This useful formula is now well known and frequently applied. In this paper, we demonstrate that the Little's formula has much more power than was previously realized when it is properly decomposed into what we call the microscopic Little's formula. We use the M/G/1 queue with server vacations as an example model to which we apply the microscopic Little's formula. As a result, we obtain a transform-free expression for the queue length distribution. Also, we briefly summarize some previous efforts in the literature to increase the power of the Little's formula.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2018년도 춘계학술발표대회
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• pp.262-265
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• 2018

MQTT 프로토콜은 저전력 대비 고성능으로 모바일 디바이스의 실시간 메시지 전송 시스템에 사용한다. 실시간 메시지 시스템을 구축하기 위해서는 신뢰적인 메시지 전송과 메시지간 순서 보장이 반드시 이루어져야 한다. 기존 연구에서는 MQTT 프로토콜의 QoS 2 레벨을 이용하여 메시지 순서를 보장하는 신뢰적인 메시지 시스템을 설계 및 구현하였으나, QoS 1 레벨보다 성능이 낮아진다. 따라서 본 논문에서는 MQTT 프로토콜의 QoS 1 레벨을 사용하고, Publish Queue를 이용하여 순서 보장과 함께 성능 향상을 고려한 메시지 전송 기법을 제안한다.