• Journal of Korea Society of Industrial Information Systems
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• v.29 no.2
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• pp.69-80
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• 2024

In this paper, we studied a discrete-time queuing system that operates under a mixed situation of D-policy and T-policy, one of the representative server control policies in queuing theory. A single server serves customers arriving by Bernoulli arrival process on a first-in, first-out basis(FIFO). If there are no customers to serve in the system, the server goes on vacation and returns, until the total service time (i.e., total amount of workload) of waiting customers exceeds predetermined workload threshold D. The operation of the system covered in this study can be used to model the efficient resource utilization of mobile devices using secondary batteries. In addition, it is significant in that the steady state waiting time and system sojourn time of the queuing system under a flexible mixed control policy were derived within a unified framework.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.15-15
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• 2003

We provide some recent results of approximation algorithms for solving Markov Games and discuss their applications to problems that arise in Computer Science. We consider a receding horizon approach as an approximate solution to two-person zero-sum Markov games with an infinite horizon discounted cost criterion. We present error bounds from the optimal equilibrium value of the game when both players take “correlated” receding horizon policies that are based on exact or approximate solutions of receding finite horizon subgames. Motivated by the worst-case optimal control of queueing systems by Altman, we then analyze error bounds when the minimizer plays the (approximate) receding horizon control and the maximizer plays the worst case policy. We give two heuristic examples of the approximate receding horizon control. We extend “parallel rollout” and “hindsight optimization” into the Markov game setting within the framework of the approximate receding horizon approach and analyze their performances. From the parallel rollout approach, the minimizing player seeks to combine dynamically multiple heuristic policies in a set to improve the performances of all of the heuristic policies simultaneously under the guess that the maximizing player has chosen a fixed worst-case policy. Given $\varepsilon$>0, we give the value of the receding horizon which guarantees that the parallel rollout policy with the horizon played by the minimizer “dominates” any heuristic policy in the set by $\varepsilon$, From the hindsight optimization approach, the minimizing player makes a decision based on his expected optimal hindsight performance over a finite horizon. We finally discuss practical implementations of the receding horizon approaches via simulation and applications.

• Health Policy and Management
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• v.26 no.4
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• pp.279-288
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• 2016

Graphic health warning on the tobacco product package is a cost-effective tobacco control policy to convey information on harmful effect of tobacco use to health, and it is known not only to motivate smokers to quit but also to deter adolescents from start smoking. In case of Korea, amendments to National Health Promotion Act requiring implementation of graphic health warning had been submitted 13 times, from 2002 to May 2015. In May 2015, the amendment had been approved by the National Assembly and it enters into force on December 23, 2016. This research analyzed the discussions from Health and Welfare Committee of the National Assembly during the implementation of the graphic health warning in order to study decision making process of legislators. Study found that there was a shift from a general opposition on implementing graphic health warning at first to a harsh conflict over relaxation of the regulation once discussing the implementation in earnest. Particularly, while the group supporting the implementation of the graphic health warning or opposing relaxation advocated the amendment with scientific and knowledge-based evidences including the World Health Organization Framework Convention on Tobacco Control, the group opposing the adoption of the amendment itself or suggesting relaxation tended to defend their position with empathy on smokers or tobacco industries.

• Health Policy and Management
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• v.31 no.4
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• pp.409-422
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• 2021

The growing use of prescription analgesic opioids has rapidly escalated the treatment of chronic pain since the 1990s; however, it is also highly needed to control opioid-related issues, including opioids misuse, abuse, and addiction. In 2018, Organization for Economic Cooperation and Development (OECD) secretariat administered the survey on opioids use and policies to OECD countries and presented it at the Health Committee meeting of December 2018. This study aimed to review the opioids use in OECD countries and their policies to prevent and reduce associated harms, also seek the available policy lessons from OECD countries. More recently, opioids prescribing rate have been increased 14.7% between 2011-2013 and 2014-2016 and steadily focused on the main substance misused and abused in Korea. In addition, policy efforts have contributed to developing a guideline for prescribing opioids to steer the appropriate use of prescription analgesic opioids since 2000 in Korea, so it is not enough to control opioids compared with other OECD countries. Therefore, taking a people-centered and public health perspective, it will consider the health system policies and interventions at a national level to improve their preparation and approach to control opioid-related issues.

• Korea journal of population studies
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• v.9 no.1
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• pp.54-68
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• 1986

This study was designed to make a comparative analysis of fertility control policies in developing countries selected from Asia and Latin America. Considering the size and the density of population, the history of the fertility control policy, and the availability of references, eight countries were chosen among Asian developing countries that have adopted the fertility control as an official policy. All of nine countries in Latin America that have adopted family planning as an official policy were included in this study. An attempt was made to formulate an analytical framework to be used for a comparative analysis of fertility control policies. It can be represented by a continuum which consists of individual approaches and structural approaches to fertility control at both extremes. It represents fairly well the controversies between those who advocate family planning and those who advocate measures beyond family planning, but assumes that the two sides of the controversy form a continuum of approaches to fertility control. Various fertility control policies of each country were placed along this continuum and analyzed. The results of the analysis can be summarized as follows: (a) Those countries that have higher population pressure in terms of either the size of population or the population density tend to adopt fertility control policies earlier in time. (b) Those countries that have higher population pressure in terms of either the size of population or the population density tend to adopt more comprehensive measures along the continuum of fertility control policies. (c) Those countries that adopted more comprehensive measures along the continuum seem to have succeeded in reducing their level of fertility more effectively. (d) Developing countries in Asia tend to adopt more comprehensive measures to control fertility than those in Latin American countries. (e) The reduction of fertility in developing countries seems to be associated with both the fertility control policies and the level of socioeconomic development.

• Health Policy and Management
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• v.26 no.2
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• pp.125-134
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• 2016

Background: Glycemic control is an effective way to reduce the cardiovascular complications of diabetes, but more than half of the adults with diabetes in Korea are improperly controlling their glycemic levels. The purpose of this study is to identify the factors associated with poor glycemic control in type 2 diabetes patients. Methods: This study analyzed 1,261 subjects ${\geq}30years$ old diagnosed with type 2 diabetes who participated in the fifth Korean National Health and Nutrition Examination Survey (2010-2012). Poor glycemic control rates were defined as hemoglobin A1c (HbA1c) level ${\geq}7%$. To shed light on the causes of poor glycemic control, socio-demographics, diabetes severity, health status, and health behavior factors were adjusted and logistic regression was done. Results: Of the total 1,261 patients, 53.0% of patients with type 2 diabetes had HbA1c ${\geq}7%$. After running a logistic regression model, the odds ratio of poor glycemic control was higher in high school graduates than elementary school graduates; in people living in Chungcheong and Jeolla/Jeju than those living in Seoul; in the group with diabetes for over 5 years had diabetes less than 5 years; in a group with insulin and oral hypoglycemic agent treatment than non-treatment; in a group with hypertriglyceridemia than without hypertriglyceridemia; and in the group with slept less than 6 hours slept 7-8 hours. Conclusion: We need a comprehensive public health policy to reduce the poor glycemic control rates in type 2 diabetes patients. We should recognize the education levels, duration of diabetes, diabetes treatment, hypertriglyceridemia, and sleep duration were associated with poor glycemic control.

• Journal of Communications and Networks
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• v.7 no.4
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• pp.408-416
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• 2005

Quality of service (QoS) provision is an important and indispensable function for multi-service wireless networks. In this paper, we present a new scheduling/admission control frame­work, including an efficient rate-guaranteed opportunistic scheduling (ROS) scheme and a coordinated admission control (ROS­CAC) policy to support statistic QoS guarantee in multi-service wireless networks. Based on our proposed mathematical model, we derive the probability distribution function (PDF) of queue length under ROS and deduce the packet loss rate (PLR) for individual flows. The new admission control policy makes admission decision for a new incoming flow to ensure that the PLR requirements of all flows (including the new flow) are satisfied. The numerical results based on ns-2 simulations demonstrate the effectiveness of the new joint packet scheduling/admission control framework.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.2
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• pp.17-33
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• 1996

Automatic transfer defined as an integrated system with a number of workstations, interstation storage buffers, automatic device and a control system, play a major role in ass production systems. Due to high capital investment needed for an automatic transferline, greater care should be taken in its design so as to maximize the system performance. One may to control the system performance is to control buffer storage. To control the interstation work-in-process inventory, we propose dual limit switches which control the buffer storage with two parameters, R and r. Under the policy, proceding station is forced down when the inventory level in the buffer reaches R until the level falls to r. For the model developed, we analyze the system characteristics and find the optimal control parameters with a serach procedure.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.939-954
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• 1995

We propose a policy for controlling the release of raw wafers into the semiconductor wafer fabrication lines. The proposed policy exploits up-to-date factory floor information gathered by tracking systems used to calculate the time and amount of a new release to minimize mean flow times and mean tardiness while maintaining the maximum output rates of the system. Extensive computer experiments show that the proposed policy results in significant improvements for the same output rates compared to existing release rules.

• Journal of Korean Institute of Industrial Engineers
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• v.11 no.2
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• pp.11-18
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• 1985

Three types of warranty policies are considered. They are (1) free warranty policy for repairable products, (2) free warranty policy for nonrepairable products, and (3) rebate warranty policy. Under each warranty policy, a single sampling attribute plan with non-destructive testing is considered. A sampling plan is characterized by the sample size and the acceptance number. For each case, characteristics of an optimum sampling plan are discussed and determined, which minimize the warranty cost and the corresponding quality control cost within the assigned producer's risk and consumer's risk.