• Management Science and Financial Engineering
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• 제2권1호
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• pp.123-145
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• 1996

We consider a priority-based multiclass queue with probabilistic feed-back. There are J service stations. Each customer belongs to one of the several priority classes, and the customers of each class arrive at each station in a Poisson process. A single server serves queued customers on a priority basis with a nonpreemptive scheduling discipline. The customers who complete their services feed back to the system instantaneously and join one of the queues of the stations or depart from the system according to a given probability. In this paper, we propose a new method to simplify the analysis of these queueing systems. By the analysis of busy periods and regenerative processes, we clarify the underlying system structure, and systematically obtain the mean for the sojourn time, i.e., the time from the arrival to the departure from the system, of a customer at every station. The mean for the number of customers queued in each station at an arbitrary time is also obtained simultaneously.

• 한국경영과학회지
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• 제39권3호
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• pp.1-5
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• 2014

We study the paper Zhernovyi and Zhernovyi [Zhernovyi, K.Y. and Y.V. Zhernovyi, "An $M^{\Theta}/G/1/m$ system with two-threshold hysteresis strategy of service intensity switching," Journal of Communications and Electronics, Vol.12, No.2(2012), pp.127-140]. In the paper, authors used the Korolyuk potential method to obtain the stationary queue length distribution. Instead, our note makes an attempt to apply the most frequently used methods : the embedded Markov chain and the supplementary variable method. We derive the queue length distribution at a customer's departure epoch and then at an arbitrary epoch.

• 대한안전경영과학회지
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• 제3권3호
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• pp.175-190
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• 2001

We propose, a new process capability index $C_{psk}$(WV) applying the weighted variance control charting method for non-normally distributed. The main idea of the weighted variance method(WVM) is to divide a skewed or asymmetric distribution into two normal distributions from its mean to create two new distributions which have the same mean but different standard deviations. In this paper we propose an example, a distributions generated from the Johnson family of distributions, to demonstrate how the weighted variance-based process capability indices perform in comparison with another two non-normal methods, namely the Clements and the Wright methods. This example shows that the weighted valiance-based indices are more consistent than the other two methods in terms of sensitivity to departure to the process mean/median from the target value for non-normal processes. Second method show using the percentage nonconforming by the Pearson, Johnson and Burr systems. This example shows a little difference between the Pearson system and Burr system, but Johnson system underestimated than the two systems for process capability.

• 농촌지도와개발
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• 제5권2호
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• pp.177-186
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• 1998

It is nearing the establishment of KAC(Korean Agricultural Chamber) as an institution for intensive reflection of farmer's public opinions in agricultural administration. In this study, researchers examined the management of Agricultural Chambers in France and Japan, which have experienced the action of Agricultural Chamber in advance of Korea. And discussed the anticipated change in agricultural extension taking advantage of departure of KAC. Discourses and movements to establish KAC is putting pressure the existing agricultural extension system into innovation. Taking a side view that there were little contribution of agents belonging to the existing agricultural extension agencies, the problem of restructuring agricultural extension system has assumed very serious dimensions. Therefore, agents in agricultural extension agencies should lay their own view before the probable reorganization of agricultural extension system.

• 품질경영학회지
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• 제23권3호
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• pp.102-112
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• 1995

Estimation of each of mean response, difference between mean responses and derivatives of the response function is a possible objective of a response surface design. These objectives are to be achieved simultaneously when an experiment is designed to improve mean response. For the situations where departure from the assumed model is suspected, first and second order designs for improving mean response are obtained by combining minimum bias designs for the individual design objectives. D- and A-optimalities are used for selecting specific second order designs. The results are applied to central composite designs.

• 한국경영과학회지
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• 제30권1호
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• pp.149-159
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• 2005

In this study, we consider characteristics of stationary waiting times in single-server 2-node tandem queues with a finite buffer, a Poisson arrival process and deterministic service times. The system has two buffers: one at the first node is infinite and the other one at the second node is finite. We show that the sojourn time or departure process does not depend on the capacity of the finite buffer and on the order of nodes (service times), which are the same as the previous results. Furthermore, the explicit expressions of waiting times at the first node are given as a function of the capacity of the finite buffer and we are able to disclose a relationship of waiting times between under communication blocking and under manufacturing blocking. Some numerical examples are also given.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2009년도 추계학술대회
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• pp.102-108
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• 2009

Despite the fact that understanding customers satisfaction with transportation services is a subject of great importance, authors, so far, found no systematic researches referred to that issue. From this point, studying the satisfaction with subways services can be extremely useful. Empirical study of key factors in the satisfaction with subway services is the departure point, which holds as objectives, and we believe, will contribute to overall increasing in the number of subways services used and in the amount of public benefits derived from that usage.

• 가족자원경영과 정책
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• 제11권4호
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• pp.171-189
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• 2007

The purpose of this ethnography is to describe and analyze the process of becoming a wild geese mother. Thirteen mothers from New York, California, and Texas of U.S.A. were interviewed with an unstructured questionnaire. There are several different patterns of the process; 'the short term', 're-departure after returning to Korea', 'a step to initiate their family's immigration', 'sudden and unintentional'. In the first stage of the family living rearrangement, the main issues are about the wider free world, proper time for leaving and proper period for staying, where to live and my husband's independent living. The wild geese mothers perform the concrete tasks about the everyday living for the new mother-child family in the foreign country. They report their subjective interpretation for their new life.

• 대한안전경영과학회지
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• 제6권4호
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• pp.215-226
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• 2004

This study develops a improved gate assignment algorithm and decision support system using its algorithm to extract a assignment result minimizing a walking distance of passengers in airport and maximizing the utilization rate of avaliable gates in domestic airports. By operation support system, it may contribute greatly in efficient enlargement of airport operation and increase the airport reliability through quickly coping with takeoff and landing delay of flight due to weather change, preservation and repair of gate, etc. Also, passengers who use airport terminal can minimize time and walking distance for departure, arrival, and transit, and it may greatly reduce the additional operation cost for common gates through maximizing the utilization rate for exclusive usage gates for airplanes which use gates.

• 대한안전경영과학회지
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• 제1권1호
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• pp.55-60
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• 1999

Presses are very widely used in industrial and commercial companies and are often the source of serious accidents occurring during operation. In Korea, the press holds the first place in the industrial hazard machines for frequency of accidents. Most of the press accidents are due to the human error. Continuous recordings of eye and hand movements that included operating errors of five experienced subjects were made during the press operation. The results showed that significant differences were observed on eye fixation time, hand fixation time, and lead departure time between the operations that has errors and no errors. The result could be used as basic data to establish a guideline for preventing the accidents.