• Journal of the Korean Operations Research and Management Science Society
• /
• v.24 no.4
• /
• pp.111-122
• /
• 1999

In this paper, we consider a queueing network model. where the population constraint within each subnetwork is controlled by a semaphore queue. The total number of customers that may be present in the subnetwork can not exceed a given value. Each node has a constant service time and the arrival process to the queueing network is an arbitrary distribution. A major characteristics of this model is that the lower layer flow is halted by the state of higher layer. We present some properties that the inter-change of nodes does not make any difference to customer's waiting time in the queueing network under a certain condition. The queueing network can be transformed into a simplified queueing network. A dramatic simplification of the queueing network is shown. It is interesting to see how the simplification developed for sliding window flow control, can be applied to multi-layered queueing network.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.34 no.4
• /
• pp.113-121
• /
• 2009

In this paper, we consider the departure process from the open and nested tandem Queueing network with population constraint and constant service times. It is known that the Queueing network can be transformed into a simple Queueing network which can be easy to analyze. Using this simple Queueing network, upper and lower bounds on the interdeparture time are obtained. We prove that the variance of the interdeparture time is bounded within these two bounds. Validation against simulation data is shown that how it works the variance of the interdeparture time within two bounds. These bounds can be applied to obtain the better variance of the interdeparture time using a suitable method.

• Proceedings of the KSME Conference
• /
• 2000.04a
• /
• pp.725-730
• /
• 2000

Genetic algorithms based on the theory of natural selection, have been applied to many different fields, and have proven to be relatively robust means to search for global optimum and handle discontinuous or even discrete data. Genetic algorithms are widely used for unconstrained optimization problems. However, their application to constrained optimization problems remains unsettled. The most prevalent technique for coping with infeasible solutions is to penalize a population member for constraint violation. But, the weighting of a penalty for a particular problem constraint is usually determined in the heuristic way. Therefore this paper proposes, the effective technique for handling constraints, the ranking penalty method and hybrid genetic algorithms. And this paper proposes dynamic mutation tate to maintain the diversity in population. The effectiveness of the proposed algorithm is tested on several test problems and results are discussed.

• Journal of Astronomy and Space Sciences
• /
• v.33 no.2
• /
• pp.101-104
• /
• 2016

More than 100 γ−ray pulsars have been discovered by the Fermi Gamma-ray Space Telescope. With a significantly enlarged sample size, it is possible to compare the properties of different classes. Radio-quiet (RQ) γ−ray pulsars form a distinct population, and various studies have shown that the properties of the RQ population can be intrinsically different from those of radio-loud (RL) pulsars. Utilizing these differences, it is possible to further classify the pulsar-like unidentified γ−ray sources into sub-groups. In this study, we suggest the possibility of distinguishing RQ/RL pulsars by their spectral shape. We compute the probabilities of a pulsar to be RQ or RL for a given spectral curvature. This can provide a key to the estimation of the intrinsic fraction of radio-quietness in the γ−ray pulsar population, which can place a tight constraint on the emission geometry.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.25 no.1
• /
• pp.15-26
• /
• 2000

We consider an open tandem queueing network with population constraint and constant service times. The total number of customers that may be present in the network can not exceed a given value k. Customers arriving at the queueing network when there are more than k customers are forced to walt in an external queue. The arrival process to the queueing network is assumed to be arbitrary. It is known that the queueing network with population constrant and constant service times can be transformed into a simple network involving only two nodes. In this paper, the departure process from the queueing network is examined using this simple network. An approximation can be calculated with accuracy. Finally, validations against simulation data establish the tightness of these.

• Journal of Korean Society of Transportation
• /
• v.24 no.3 s.89
• /
• pp.7-15
• /
• 2006

A large sample can Provide more information about the Population. As the sample size Increases, analysts will be more confident about the survey results. On the other hand, the costs for survey will increase in time and manpower. Therefore, determination of the sample size is a trade-off between the required accuracy and the cost. In addition, permitted error and significance level should be considered. Sample size determination in surveys for O/D estimation is also connected with confidence of survey result. However, the past methods were usually too simple to consider confidence. Therefore, a new method for O/D surveys was Proposed and it was accurate enough, but it has too large sample size when we have current budget constraint. In this research, several minimum sample size determination methods for origin-destination survey under budget constraint were proposed. Each method decreased sample size, but has its own advantages. Selection of the sample size will depend on the study Purpose and budget constraint.

• Journal of Korean Society for Quality Management
• /
• v.23 no.3
• /
• pp.126-139
• /
• 1995

We describe a formal approach to the construction of optimal classification rule for the two-group normal classification with equal population mean problem. Based on the utility function of Bernardo, we suggest a balanced design for the classification and construct the optimal rule under the balanced design condition. The rule is characterized by a constrained minimization of total risk of misclassification, the constraint of which is constructed by the process of equation between expected utilities of the two group conditional densities. The efficacy of the suggested rule is examined through numerical studies. This indicates that, in case little is known about the relative population sizes, dramatic gains in accuracy of classification result can be achieved.

• Journal of the Korean Statistical Society
• /
• v.24 no.2
• /
• pp.453-470
• /
• 1995

We describe a constrained optimal classification rule for the case when the prior probability of an observation belonging to one of the two populations is unknown. This is done by suggesting a balanced design for the classification experiment and constructing the optimal rule under the balanced design condition. The rule si characterized by a constrained minimization of total risk of misclassification; the constraint of the rule is constructed by the process of equation between Kullback-Leibler's directed divergence measures obtained from the two population conditional densities. The efficacy of the suggested rule is examined through two-group normal classification. This indicates that, in case little is known about the relative population sizes, dramatic gains in accuracy of classification result can be achieved.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.27 no.1
• /
• pp.67-80
• /
• 2024

In south korea, the elderly population has been continuously increasing, so blind spots in administrative welfare services for the elderly are expected to increase. therefore, this study aimed to analyze the types of blind spots in administrative welfare services for the elderly in gijang-gun, Busan, where the elderly population is increasing. using a network analysis, the demand and service supply ranges were derived. after that, in comparison to their sizes, the blind spots were divided into three types: i) blind spots in service supply, ii) blind spots in mobility constraint, and iii) dual blind spots. As a result, in gijang-gun, the blind spots in mobility constraint were 21.5%, the dual blind spots were 9.5%, and the blind spots in service supply were 3.2%. Based on these results, this study suggested policy directions for resolving the blind spots in administrative welfare services for the elderly by type.

• Physical Therapy Rehabilitation Science
• /
• v.2 no.2
• /
• pp.92-98
• /
• 2013

Objective: Constraint induced aphasia therapy (CIAT) is a more intensive form of language treatment for aphasia as compared to traditional treatments. This study examined whether there are differences in cortisol stress levels between the two methods of aphasia treatment as well as effects on language skills. Design: Randomized controlled trial. Methods: A total of 20 participants with expressive aphasia were randomly placed into one of the two treatment groups. The CIAT group received 10 days of intensive treatment over two weeks. The traditional therapy group received 6 days of treatment over 2 weeks. All participants in each group provided salivary cortisol samples before treatment, at the mid-point of treatment, and at the conclusion of treatment. Language skills were assessed before treatment and at the conclusion of treatment. Results: A significantly higher proportion of individuals in the CIAT treatment group had increased salivary cortisol stress levels when compared to the traditional treatment group at the mid-point of the program (80% versus 30% respectively, p<0.05). There was no significant difference in the proportion of individuals with increased cortisol stress by the end of the treatment. Language scores for word repetition and overall aphasia quotient significantly improved for the CIAT group when compared to the traditional group (p<0.05). Conclusions: The CIAT treatment appears to initially create increased psychophysiological stress as compared to the traditional treatment. In spite of the initial increases in psychophysiological stress, participants appear to become conditioned to the challenge and ultimately have enhanced benefit from CIAT treatment.