• 한국통신학회논문지
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• 제27권8C호
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• pp.729-740
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• 2002

본 논문에서는 광 인터넷 망의 가상망 재구성을 위하여 최적의 망 재구성 정책을 고려한 보상-비용 함수를 최대화하는 다단계 결정 문제로 정의 하였다. 그리고 트래픽 요구사항을 만족하기 위해서 노드 교환 기법에 근거한 새로운 휴리스틱 알고리즘을 제안하였다. 또한 트래픽 예측 기법을 사용하여 휴리스틱 알고리즘에 의해 발생하는 근사 문제를 해결 하고, 이를 바탕으로 트래픽 예측 다단계 재구성 정책을 제안하였다. 실험결과 다단계 재구성 정책은 물리적 자원이 제한된 환경에서 기존의 방법에 비해 뛰어난 성능을 보였다.

• 보건행정학회지
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• 제25권4호
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• pp.333-342
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• 2015

Background: The purposes of this study is to analysis the differences of the job satisfaction between regular and non-regular workers in hospitals. Methods: The samples used for data analysis are 632 workers of 6 hospitals using a standardized questionnaires in B, C, D, and G provinces. In research methodology, all the data were analyzed with descriptive statistics, t-test, Pearson's correlation, and multiple linear regression analysis. Results: In case of regular workers, communication, working conditions and employee benefit, and education were found to have a significant positive (+) effect on job satisfaction. In case of non-regular workers, empowerment, reward systems, communication, working conditions, and employee benefit had a significant positive (+) effect on job satisfaction. Conclusion: These results showed that hospitals needed to reinforce communication, working conditions and employee benefit to regular and non-regular workers in order to improve job satisfaction. Especially, more empowerment, working conditions, and employee benefit should be given to non-regular workers.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2004년도 학술발표논문집
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• pp.123-128
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• 2004

A finite dam under $P_{\lambda,;,T}^M-policy$ is considered, where the input of water is formed by a Wiener process subject to random jumps arriving according to a Poisson process. Explicit expression is deduced for the stationary distribution of the level of water. And the long-run average cost per unit time is obtained after assigning costs to the changes of release rate, a reward to each unit of output, and a penalty which is a function of the level of water in the reservoir.

• 한국언론정보학보
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• 제36권
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• pp.231-253
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• 2006

IT 기술의 성장에 기초한 우리 사회의 각종 뉴미디어의 개발과 도입의 속도, 보급과 서비스의 확산정도 등은 국제적 관심을 주도할 만큼 폭발적이다. 한편 국가 정보화 차원에서 강력한 정책 드라이브를 바탕으로 추진된 정보 인프라의 확대 역시 그에 못지않다. 그러나 문제는 뉴미디어-정보화 정책이 추구하는 산업경제적 가치창출, 사회문화적 가치창출, 지식기반의 확충을 통한 지식사회/지식국가의 토대구축이라는 정책목표가 '사회의 질적 발전(quality development of society)'보다는 '기술과 산업의 양적 성장(quantity growth of industry and technology)'이라는 편향적 형태로 진전되고 있다는 것이다. 이는 개별 정책의 결과이기도 하지만 보다 근본적으로는 개발주의 패러다임(developmentalism)에 기초하고 있는 뉴미디어-정보화 정책의 구조적인 문제에서 비롯된 것이다. 이를 극복하기 위해서 우선적으로 요구되는 것은 '지식 IT 전략(knowledge IT strategy)'에 기초한 뉴미디어-정보화의 질적 발전, 즉 원천기술과 특허의 확보와 그를 통한 기술표준의 구축, 내용과 수준을 갖춘 콘텐츠의 계발, 사회적 지식 네트워크의 구성 등에 부합하는 정책 패러다임으로의 전환이다.

• Industrial Engineering and Management Systems
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• 제4권2호
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• pp.198-206
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• 2005

The single sourcing policy, in which an automobile manufacturer purchases identical or similar parts from one supplier, has an advantage of scale economy. Meanwhile, multiple sourcing policy, which allows procuring similar parts from multiple suppliers, has benefits of dispersing risks and promoting competition among suppliers. This paper analyzes the procurement policies by presenting a model of the Japanese automobile parts trade. It concludes that maturity of technology involved should be taken into account besides above-mentioned factors which have traditionally been recognized. For parts produced using evolving technologies, the single sourcing enhances purchaser’s benefits because of the scale economy in learning process. In the meantime, multiple sourcing is more beneficial to the purchaser if the parts are based on mature technologies. In either policy, if the technology involved is evolving, motivating suppliers by returning a great part of cost reduction as a reward to them may eventually increase profit for the purchaser. The conclusion supports the situation where the number of suppliers is being cut down as the trend of modularization and system deliveries of parts progresses in the auto parts industry, and suggests that returning part of benefits to parts suppliers may be encouraged from the viewpoint of auto manufacturers’ own interest.

• 한국공간구조학회논문집
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• 제21권2호
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• pp.41-48
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• 2021

A smart tuned mass damper (TMD) is widely studied for seismic response reduction of various structures. Control algorithm is the most important factor for control performance of a smart TMD. This study used a Deep Deterministic Policy Gradient (DDPG) among reinforcement learning techniques to develop a control algorithm for a smart TMD. A magnetorheological (MR) damper was used to make the smart TMD. A single mass model with the smart TMD was employed to make a reinforcement learning environment. Time history analysis simulations of the example structure subject to artificial seismic load were performed in the reinforcement learning process. Critic of policy network and actor of value network for DDPG agent were constructed. The action of DDPG agent was selected as the command voltage sent to the MR damper. Reward for the DDPG action was calculated by using displacement and velocity responses of the main mass. Groundhook control algorithm was used as a comparative control algorithm. After 10,000 episode training of the DDPG agent model with proper hyper-parameters, the semi-active control algorithm for control of seismic responses of the example structure with the smart TMD was developed. The simulation results presented that the developed DDPG model can provide effective control algorithms for smart TMD for reduction of seismic responses.

• 한국멀티미디어학회논문지
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• 제23권7호
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• pp.830-839
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• 2020

As a popular mathematical framework for modeling decision making, Markov decision process (MDP) has been widely used to solve problem in many engineering fields. MDP consists of a set of discrete states, a finite set of actions, and rewards received after reaching a new state by taking action from the previous state. The objective of MDP is to find an optimal policy, that is, to find the best action to be taken in each state to maximize the expected discounted reward of policy (EDR). In practice, MDP is typically unknown, so simulation-based policy improvement (SBPI), which improves a given base policy sequentially by selecting the best action in each state depending on rewards observed via simulation, can be a practical way to find the optimal policy. However, the efficiency of SBPI is still a concern since many simulation samples are required to precisely estimate EDR for each action in each state. In this paper, we propose a method to select the best action accurately in each state using a small number of simulation samples, thereby improving the efficiency of SBPI. The proposed method accumulates the simulation samples observed in the previous states, so it is possible to precisely estimate EDR even with a small number of samples in the current state. The results of comparative experiments on the existing method demonstrate that the proposed method can improve the efficiency of SBPI.

• Journal of Communications and Networks
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• 제11권6호
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• pp.634-644
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• 2009

A diversity of wireless networks, with rapidly evolving wireless technology, are currently in service. Due to their innate physical layer vulnerability, wireless networks require enhanced security components. WLAN, WiBro, and UMTS have defined proper security components that meet standard security requirements. Extensive research has been conducted to enhance the security of individual wireless platforms, and we now have meaningful results at hand. However, with the advent of ubiquitous service, new horizontal platform service models with vertical crosslayer security are expected to be proposed. Research on synchronized security service and interoperability in a heterogeneous environment must be conducted. In heterogeneous environments, to design the balanced security components, quantitative evaluation model of security policy in wireless networks is required. To design appropriate evaluation method of security policies in heterogeneous wireless networks, we formalize the security properties in wireless networks. As the benefit of security protocols is indicated by the quality of protection (QoP), we improve the QoP model and evaluate hybrid security policy in heterogeneous wireless networks by applying to the QoP model. Deriving relative indicators from the positive impact of security points, and using these indicators to quantify a total reward function, this paper will help to assure the appropriate benchmark for combined security components in wireless networks.

• 보건행정학회지
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• 제24권4호
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• pp.330-341
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• 2014

Background: The purpose of this study is to investigate the factors that affect the participation of union members who involved in the Korean health cooperatives. Methods: Questionnaires were collected from 1,041 respondents who voluntarily participated in seven health cooperatives. In order to verify the hypothesis, collected data were analyzed using binomial logistic regression. Results: Longer tenure, higher collective motive, organizational age were associated with types of participation. In operative participation, marital status, higher reward motive, better accessibility to the cooperatives influenced concern about the high-level participation. Organizational age were associated with the high-level participation in management participation. Longer tenure, interaction with staff, management participation were involved in additional investment. Conclusion: This is the first study to statistically prove that the influencing factors on the participation in the health cooperatives. Based on these findings, the provision of differentiated strategies should be useful for increase of participation.

• 보건행정학회지
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• 제24권3호
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• pp.291-300
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• 2014

Background: The efficient knowledge management in hospital organization is generally known as the important activities relevant to employees' knowledge sharing behavior and work performance. This research examined factors affecting employees' knowledge sharing behavior and work performance in top 4 university hospitals. This study is based on individual factors such as incentives, reciprocity, behavioral control, and subjective norms. Also, there are organizational factors such as CEO support, learning climate, IT system, rewards system, and trust. Methods: Data was collected from employees who are working at 3 hospitals university in Seoul and 1 university hospital in Gyeonggi-Do through the self-administered questionnaires. A total of 779 questionnaires were analyzed by PASW SPSS ver. 18.0. (SPSS Inc., Chicago, IL, USA). Results: The significant variables affecting knowledge sharing behavior are behavioral control (in individual factor) and CEO, IT system, and trust (in organization factor). Also the significant variables affecting work performance are incentives, reciprocity, subjective norms, and behavioral control (in individual factor) and CEO support, IT system, reward system, and trust (in organization factor). Conclusion: The personality and organization characteristics factors is important to improve knowledge sharing behavior and work performance of hospital employees. Therefore, to make more efficient knowledge management is to build and system knowledge sharing culture, system, and leadership and to develop practical strategies.