• Communications for Statistical Applications and Methods
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• 제17권2호
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• pp.165-181
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• 2010

This paper presents some chain ratio-type estimators for estimating finite population variance using two auxiliary variables in two phase sampling set up. The expressions for biases and mean squared errors of the suggested c1asses of estimators are given. Asymptotic optimum estimators(AOE's) in each class are identified with their approximate mean squared error formulae. The theoretical and empirical properties of the suggested classes of estimators are investigated. In the simulation study, we took a real dataset related to pulmonary disease available on the CD with the book by Rosner, (2005).

• 한국전자파학회논문지
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• 제21권7호
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• pp.734-743
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• 2010

본 논문은 다중 도체 전송선 해석법과 chain matrix 알고리즘을 이용하여 twisted cable과 같은 비균일 전송선의 EMP 결합을 해석하였다. 전송선의 EMP 결합 해석을 위해 BLT(Baum-Liu-Tesche) 해석법이 널리 사용되고 있으나, twisted cable과 같은 비균일 전송선에 기존의 BLT 해석법을 바로 적용하기는 어렵다. Twisted cable과 같은 비균일 전송선을 해석하기 위해 수많은 작은 길이의 균일 전송선으로 나누어 모델링하였으며, 전체 비균일 전송선의 결합 특성은 각각의 균일 전송선의 EMP 결합 분석을 통해 최종적인 전송선의 결합 특성을 구함으로 써 가능해진다. 이러한 비균일 전송선 EMP 결합 해석 기법을 검증하기 위해 균일 전송선에 대하여 기존의 BLT 해석 결과와 비교하였으며, 제시된 비균일 전송선 EMP 결합 해석 기법을 지표면 위에 놓여 있는 twisted cable에 적용하여 대기 중의 핵폭발에 의한 HEMP(High altitude Electromagnetic Pulse)와 같은 매우 강한 펄스가 입사되었을 때, 전송선에 연결된 부하에 유기되는 전류(또는 전압) 응답을 분석하였다.

• 대한수학회지
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• 제55권5호
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• pp.1257-1268
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• 2018

In this article we first investigate a sort of unit-IFP ring by which Antoine provides very useful information to ring theory in relation with the structure of coefficients of zero-dividing polynomials. Here we are concerned with the whole shape of units and nilpotent elements in such rings. Next we study the properties of unit-IFP rings through group actions of units on nonzero nilpotent elements. We prove that if R is a unit-IFP ring such that there are finite number of orbits under the left (resp., right) action of units on nonzero nilpotent elements, then R satisfies the descending chain condition for nil left (resp., right) ideals of R and the upper nilradical of R is nilpotent.

• Journal of applied mathematics & informatics
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• 제28권1_2호
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• pp.153-162
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• 2010

The finite buffer GI/G/1/K system is set up by using an unconventional arrangement of the state space, in which the remaining interarrival time or service time is chosen as the level. The stationary distributions of resulting Markov chain can be explicitly determined, and the chain is positive recurrent without any restriction. This is an advantage of this method, compared with that using the elapsed time approach [2].

• 산업공학
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• 제18권1호
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• pp.63-72
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• 2005

In this paper, we present a distribution planning method for a supply chain. Like a typical distribution network of manufacturing firms, we have the form of arborescence. To consider more realistic situation, we investigated that an outside supplier has limited capacity. The customer demands are given in deterministic form in finite number of discrete time periods. In this environment, we attempt to minimize the total costs, which is the sum of inventory holding and backorder costs over the distribution network during the planning horizon. To make the best of the restricted capacity, we propose the look-ahead feature. For looking ahead, we convert this problem into a single machine scheduling problem and utilize tabu search approach to solve it. Numerous simulation tests have shown that the proposed algorithm performs quite well.

• 대한수학회보
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• 제32권2호
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• pp.171-177
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• 1995

Let P be a finite poset and let $\mid$P$\mid$ be the number of vertices in pp. A subposet of P is a subset of P with the induced order. A chain C in P is a subposet of P which is a linear order. The length of the chain C is $\mid$C$\mid$ - 1. A linear extension of a poset P is a linear order $L = x_1, x_2, \ldots, x_n$ of the elements of P such that $x_i < x_j$ is P implies i < j. Let L(P) be the set of all linear extensions of pp. E. Szpilrajn [5] showed that L(P) is not empty.

• 한국국방경영분석학회지
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• 제17권1호
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• pp.1-24
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• 1991

This report concerns the study of deciding replacement requirements for 1/4ton truck in Korea. Two causes of replacement, accidental loss and wearout are considered in the replacement requirements model which was developed in Defence Logistics Agency. The model represents the state of 1/4 ton truck inventory over time as a finite Markov chain process. An accidental loss rate, yearly usage rates. wearout rates are used in conjuction with the current mileage distribution of the inventory to forecast replacement requirements in future time periods.

• 한국정보통신학회논문지
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• 제12권12호
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• pp.2253-2258
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• 2008

산화물 반도체 감지막이 동작온도에 따라 감응특성을 가지는 마이크로 흐름센서를 설계하기 위해서 통계적 수법에 기초한 Markov 체인 MCM을 이용하여 기초방정식을 정식화하고 마이크로 소자의 열 전달특성을 해석하였다. 계산 결과를 통하여 기존 유한차분법이 가지는 계산 정밀도와 차이가 없음을 확인하였다. 본 논문에서 제안한 Markov 체인 MCM을 활용하면 다양한 마이크로 소자의 열전달 특성과 같은 물리적 특성을 해석하고 설계하는데 유용할 것으로 판단된다.

• 한국정보통신학회논문지
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• 제27권1호
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• pp.135-138
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• 2023

In this paper, we study real-time error in the context of monitoring a binary information source through a delay system. To derive the average real-time error, we model the delay system as a discrete time Geo/D/1/1 queueing model. Using a discrete time three-dimensional Markov chain with finite state space, we analyze the queueing model. We also perform some numerical analysis on various system parameters: state transition probabilities of binary information source; transmission times; and transmission frequencies. When the state changes of the information source are positively correlated and negatively correlated, we investigate the relationship between transmission time and transmission frequency.

• 대한수학회보
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• 제46권4호
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• pp.673-689
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• 2009

We analyze $MAP_1,\;MAP_2$/G/1 finite queues with service scheduling function dependent upon queue lengths. The customers are classified into two types. The arrivals of customers are assumed to be the Markovian Arrival Processes (MAPs). The service order of customers in each buffer is determined by a service scheduling function dependent upon queue lengths. Methods of embedded Markov chain and supplementary variable give us information for queue length of two buffers. Finally, the performance measures such as loss probability and mean waiting time are derived. Some numerical examples also are given with applications in telecommunication networks.