• Journal of Korean Institute of Industrial Engineers
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• v.39 no.4
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• pp.260-270
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• 2013

This paper proposes a strategic portfolio model for managing performance of online games. The portfolio matrix is composed of two dimensions: financial performance and non-financial performance. Financial performance is measured by the conventional measure, average revenue per user (ARPU). In terms of non-financial performance, five non-financial key performance indicators (KPIs) that have been widely used in the online game industry are utilized: RU (Register User), VU (Visiting User), TS (Time Spent), ACU (Average Current User), MCU (Maximum Current User). Data envelopment analysis (DEA) is then employed to produce a single performance measure aggregating the five KPIs. DEA is a linear programming model for measuring the relative efficiency of decision making unit (DMUs) with multiple inputs and outputs. This study employs DEA as a tool for multiple criteria decision making (MCDM), in particular, the pure output model without inputs. Combining the two types of performance produces the online game portfolio matrix with four quadrants: Dark Horse, Stop Loss, Jack Pot, Luxury Goods. A case study of 39 online games provided by company 'N' is provided. The proposed portfolio model is expected to be fruitfully used for strategic decision making of online game companies.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1118-1124
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• 2014

This paper proposes a novel controller design scheme for multimachine power systems based on the explorized policy iteration. Power systems have several uncertainties on system dynamics due to the various effects of interconnections between generators. To solve this problem, the proposed method solves the LQR (Linear Quadratic Regulation) problem of isolated subsystems without the knowledge of a system matrix and the interconnection parameters of multimachine power systems. By selecting the proper performance indices, it guarantees the stability and convergence of the LQ optimal control. To implement the proposed scheme, the least squares based online method is also investigated in terms of PE (Persistency of Excitation), interconnection parameters and exploration signals. Finally, the performance and effectiveness of the proposed algorithm are demonstrated by numerical simulations of three-machine power systems with governor controllers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.451-458
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• 2012

This paper addresses the problem that policy iteration (PI) for continuous-time (CT) systems requires explorations of the state space which is known as persistency of excitation in adaptive control community, and as a result, proposes a PI scheme explorized by an additional probing signal to solve the addressed problem. The proposed PI method efficiently finds in online fashion the related CT linear quadratic (LQ) optimal control without knowing the system matrix A, and guarantees the stability and convergence to the LQ optimal control, which is proven in this paper in the presence of the probing signal. A design method for the probing signal is also presented to balance the exploration of the state space and the control performance. Finally, several simulation results are provided to verify the effectiveness of the proposed explorized PI method.

• Asian Journal of Innovation and Policy
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• v.6 no.3
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• pp.274-294
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• 2017

While studies have viewed the effect of Chinese talent-attracting programs launched by government since reform and open door policy, little of them has assessed these programs empirically and pertinently. This article intends to assess an important program - the Thousand Youth Talents Program (TYTP). Frist, this paper proposed a transnational migration matrix of the academics to clarify the dynamic mechanism of academic brain gain at the high end. Then, the Kaplan-Meier analysis and Cox regression model are used to empirically analyze the policy effect of TYTP. The results show that, academic ability have double edged impacts on brain gain at the high end, some scholars whose last employer's academic ranking is world's Top100 have stronger willing to return, and the negative effect of academic ranking decreases with time passing; while scholars with a tenure-track position, a tenure position or a permanent position tend to stay overseas, and the hazard rate of staying increases with age. The older scholars have more intentions to go back China, while gender was not a significant factor influencing academic return at the high end. That is, the talent-attracting programs has partly succeeded in bringing back the academics at the high end.

• Journal of Agricultural Extension & Community Development
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• v.28 no.1
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• pp.53-68
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• 2021

This study aimis to identify policy priorities for promoting youth activities through the Importance-Performance Analysis (IPA). IPA is used to identify policy priorities for promoting local youth activities. The IPA tabulated result is presented in a two-dimensional grid to showing for promoting local youth activities, The require concentrate support part is divided into 3 parts. Problem solve supporting at work development of leisure activities programs, leisure activities programs developing and development of leisure-related professionals. And leisure-related professionals developing. The next parts that require continuous management were divided into four parts. The next parts that require continuous management is divided into four parts. Creating rental housing for young people, support for housing expenses supporting, loans supporting, and Holiday guaranteed. Based on the factors that support youth activities that make up the IPA matrix, the implications of revitalizing local youth activities is presented as below. First, ensuring employment of local youth and efforts to create sustainable jobs. Second, continuous efforts to improve the housing conditions of local youth, and third, policy support is needed for local youth to do various leisure activities.

• Korea Journal of Hospital Management
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• v.23 no.2
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• pp.28-41
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• 2018

Purpose: This study purposed to analyze the spatial accessibility of mental health institutions in Ganwon-Do using Geographic Information System and to suggest policy implications. Methodology: Network analysis was applied to assess the spatial accessibility of mental health institutions in Gangwon-Do. To perform the network analysis, network data set was built using administrative district map, road network, address of mental health institutions in Gangwon-Do. After building network data set, Two network analysis methods, 1) Service area analysis, 2) Origin Destination cost matrix were applied. Service area analysis calculated accessive areas that were within specified time. And using Origin Destination cost matrix, travel time and road travel distance were calculated between centroids of Eup, Myeon, Dong and the nearest mental health institutions. Result: After the service area analysis, it is estimated that 19.63% of the total areas in Gangwon-Do takes more than 60 minutes to get to clinic institutions. For hospital institutions, 23.08% of the total areas takes more than 60 minutes to get there. And 59.96% of Gangwon-do takes more than 30 minutes to get to general hospitals. The result of Origin-Destination cost matrix showed that most Eup Myeon Dong in Gangwon-Do was connected to the institutions in Wonju-si, Chuncheon-si, Gangneung-si. And it showed that there were large regional variation in time and distance to reach the institutions. Implication: Results showed that there were regional variations of spatial accessibility to the mental health institutions in Gangwon-Do. To solve this problem, Several policy interventions could be applied such as mental health resources allocation plan, telemedicine, providing more closely coordinated services between mental health institutions and community mental health centers to enhance the accessibility.

• Korean Journal of Social Welfare Studies
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• v.40 no.1
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• pp.261-296
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• 2009

I constructed the 2003 Korean 'social accounting matrix'(SAM) to analyze the multipliers of total demand for each economic activity. I find that the relative magnitude of the influence of the welfare policy to the national economy measured by input-output production multipliers tends to be underestimated compared to SAM multipliers. This is because the total demand multipliers of SAM include the private sector effects, which is not considered in the input-output model. The result also support that income inflows in public service areas including education, health and social work, generate gains in the relative income of households.

• Resources Recycling
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• v.27 no.3
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• pp.66-77
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• 2018

The import amount of rare metal in Korea is about 6,034 million USD, but the self-sufficiency of rare metals is about only 1%. In order to secure the stable supply of rare metals, it is necessary to operate an efficient stockpile system. In this study, we established a system to assess the adequacy of stockpiles by quantifying the risk factors of tangible and intangible risks in order to establish an efficient stockpile strategy. The model developed in this study aims to select the rare metals that need to be stockpiled first and to suggest the direction of the stockpiling policy in accordance with technological change and market change from the mid and long term viewpoint. The evaluation results derived from the model can quantitatively measure the security level of each rare metal and enable relative comparison between the rare metals using criticality matrix. Therefore, it is expected that more efficient stockpile policy will be possible if the proposed model is utilized in the future policy making.

• Health Policy and Management
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• v.8 no.2
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• pp.110-124
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• 1998

Determining of Strategic Business Units in the organization is a major critical process for improving the organizational performance. On increasing the demands for extension in function of health center, many health centers are trying to provide the various services. But most health center determined the kind and level of service without scientific considerations. The purposes of this study are to develope the model for determination of strategic business units in health center and to test the availability of implementation for it. Our model is rooted from the McKinsey matrix analysis of Product Portfolio Analysis which used widely in marketing field. We modified the evaluation criteria of the McKinsey matrix analysis for health care field appropriately. Our evaluation criteria are categorized into two concepts; contribution of service, availability of service. At first, in terms of contribution of service, market size, market growth rate, needs and demands of regional people, existences of alternative services in that region, correspondence with health policy. The other component, availability of service are included the availability of manpower, financial availability, the level of knowhow on service, acceptance of health care manpower. In the result of analysis, we could conclude that antismoking and antialcoholics education programs, health screening program are important strategically in that aspects of contributions and availability of services. Also, vaccination program is important in that aspect of service availability and diet and exercise program, health library are meaningful in the aspect of service contribution. Therefore, we think that efforts to investigate the evaluation criteria for priority setting or determination of service area in health center are useful challenges.

• Journal of Communications and Networks
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• v.16 no.2
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• pp.193-201
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• 2014

In cognitive radio networks, the packet transmissions of the secondary users (SUs) can be interrupted randomly by the primary users (PUs). That is to say, the PU packets have preemptive priority over the SU packets. In order to enhance the quality of service (QoS) for the SUs, we propose a spectrum access strategy with an ${\alpha}$-Retry policy. A buffer is deployed for the SU packets. An interrupted SU packet will return to the buffer with probability ${\alpha}$ for later retrial, or leave the system with probability (1-${\alpha}$). For mathematical analysis, we build a preemptive priority queue and model the spectrum access strategy with an ${\alpha}$-Retry policy as a two-dimensional discrete-time Markov chain (DTMC).We give the transition probability matrix of the Markov chain and obtain the steady-state distribution. Accordingly, we derive the formulas for the blocked rate, the forced dropping rate, the throughput and the average delay of the SU packets. With numerical results, we show the influence of the retrial probability for the strategy proposed in this paper on different performance measures. Finally, based on the trade-off between different performance measures, we construct a cost function and optimize the retrial probabilities with respect to different system parameters by employing an iterative algorithm.