• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.219-231
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• 2003

This paper aims to study the problem of combined harvesting of a system involving one predator and two prey species fishery in which the predator feeds more intensively on the more abundant species. Mathematical formulation of the optimal harvest policy is given and its solution is derived in the equiblibrium case by using Pontryagin's Maximum principle. Dynamic optimization of the harvest policy is also discussed by taking E(t), the combined harvest effort, as a dynamic variable. Biological and bioeconomic interpretations of the results associated with the optimal equilibirum solution are explained. The significance of the constraints required for the existence of an optimal singular control are also given.

• Journal of Society of Preventive Korean Medicine
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• v.8 no.2
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• pp.1-12
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• 2004

This paper estimated the demand and supply of physicians for oriental medicine for the period of $2009{\sim}2019$. Two equation models were used in the estimation of manpower. In 2004, the total number of physicians of oriental medicine was amounted to 13,662 registered and 10,532 available in clinical practice, respectively. According to estimates in the study, overall excess supply of physician manpower in oriental medicine was expected in the period, such as $5,300{\sim}5,700$ persons in 2009 and $900{\sim}1,700$ persons in 2019. However, the excess supply would be mitigated after 2019 mainly due to an increase in demand for oriental medical services. Specially, opening medical service market to overseas could be an exogenous variable in physician supply. An alternative manpower policy for oriental medical doctors is needed in a way of controlling oversupply.

• Health Policy and Management
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• v.4 no.1
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• pp.123-137
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• 1994

The objectives of this research is to find the factors which determined hospital profitability. The unit of analysis is hospital, and the data is collected from two sources. One source is derived from Ministry of Health and Social Affairs(4 years' data from 134 hospitals), and another source is derived from Sam-II Accounting Co.(1 year's data from 37 hospitals). Hospital profitability, which is dependent variable in our research, is measured with financial ration, such as ROI(reture on investment). The major findings are as follows; 1) The hospital profitability is determined with not hospital type itself but management-incentives associated with hospital type. 2) The maximum profitability is obtained in 775 bed-size. 3) The hospital location isn't a factor to determine profitability 4) The internal control and management, such as account receivables, inventory, fixed assert investment, is major factor to hospital profitability.

• Health Policy and Management
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• v.6 no.2
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• pp.91-114
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• 1996

In this research, the Data Envelopment Analysis(DEA) was applied to measure production efficiency of Public Corporation Medical Centers(PCMCs) operating in Korea. The focus of this research is triple. First, identifing convenience and usefulness of DEA to measure the relative efficiency among PCMCs. Second, assessing magnitudes of the relative efficiency for each PCMC. Third, adding insights into some factors resulting inefficiency in PCMCs. Then, in this paper technical efficiency and scale efficiency measured by DEA[introduced by Charnes, Cooper, and Rhoides(1978) and Banker, Charnes, and Cooper(1984)] were analyzed and a new separate variable was introduced which makes it possible to determine whether operations were conducted in regions of increasing, constant or decresing returns to scale(in multiple input and output situations). And a multi-factor Tobit analysis was conducted to see which variables are associated with PCMC's efficiency.

• Journal of the Korean Statistical Society
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• v.31 no.4
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• pp.491-507
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• 2002

We analyze a single server bulk input queue with optional server vacations under a single vacation policy and balking phenomenon. The service times of the customers as well as the vacation times of the server have been assumed to be arbitrary (general). We further assume that not all arriving batches join the system during server's vacation periods. The supplementary variable technique is employed to obtain time-dependent probability generating functions of the queue size as well as the system size in terms of their Laplace transforms. For the steady state, we obtain probability generating functions of the queue size as well as the system size, the expected number of customers and the expected waiting time of the customers in the queue as well as the system, all in explicit and closed forms. Some special cases are discussed and some known results have been derived.

• World Technopolis Review
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• v.8 no.2
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• pp.104-119
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• 2019

Innovation clusters are essential in the economic development of many developed countries across the world. While they present ways for under-developed and developing countries to grow their economies, fully operational innovation clusters are yet to be established in Nigeria. Many experts argue that learning from experience is an effective way of galvanizing economic development. Therefore, in this study, an empirical analysis involving a multi-variable quantitative analysis was used to examine the factors that influence the performance of the Daedeok Innopolis Innovation Cluster (South Korea). The results obtained show that the investment in education, Research and Development (R&D), labor capacity of key players within the innovation cluster, and the transfer of technology (within the cluster) were essential factors that influence the performance of the Daedeok Innopolis Innovation Cluster.

• Health Policy and Management
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• v.12 no.3
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• pp.77-98
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• 2002

The purpose of this study is to empirically investigate the determinants of occupational commitment of hospital nurses. For this study, a causal model of occupational commitment of hospital nurses was constructed based on the exchange theory. The sample of this study consisted of 329 nurses from S general hospitals located in Seoul and south-eastern area of Korea. Data were collected with self-administered questionnaires and analyzed using hierarchical multiple regression. It was found that four task reward variables(variety, significance, workload and resource inadequacy), one social reward variable(supervisory support) and two organizational reward variables(promotional chances and pay) had significant net effect on hospital nurses' occupational commitment. The implications of these findings were discussed and the suggestions for future research wert advanced.

• Korean System Dynamics Review
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• v.14 no.3
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• pp.75-103
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• 2013

The purpose of this study is to use system dynamics to establish the relation among each variable through the construction process of Community Planning Model, and examine what changes policy scenarios per alternative cause in Community Planning through policy simulation of the constructed model. Therefore, this study extracted chief variables of Community Planning Projects through precedent researches related to Community Planning, and extracted variables were prepared as causal map to examine in what causal cycle feedback structure within Community Planning they can be explained. Next, Community Planning Model was constructed based on the prepared causal map. The model was verified by specialists' interviews and simulation of example areas. This study, which aimed to construct Community Planning Model using system dynamics, has a significance in that it prepared the foundation to provide useful methodology in monitoring the progress of project or establishing the plan of future Community Planning Projects.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.1
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• pp.13-34
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• 1991

A production/inventory system is considered in which a production facility produces one type of product. The demand for the product is given by a compound Poison process and is supplied directly from inventory when inventory is available and is lost when inventory is out of stock. The processing time to produce one item is assumes to follow a general distribution. An (s, S) policy is considered in which production stops at the instant the stock on hand reachs S and the setup of the production facility begins at an inspection point when the stock on hand drops to or below s for the first time. The time interval between two successive inspection points during a non-production period is a random variable which follows a general distribution.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2017.11a
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• pp.1213-1244
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• 2017

This study used a resource-based perspective to analyse the effects of organizational composition on the R&D performance of science and technology government-funded research institutes (GFRIs). We assumed that the composition of each GFRI would eventually be regarded as absorptive capacity and act as a moderating variable between R&D investment and performance. We used a panel generalized least squares (GLS) model with fixed effects to analyse panel data from 115 Korean GFRIs between 2011 and 2015. Our findings show that R&D investment of GFRIs has a direct and positive effect on performance. We also analysed how organizational composition can moderate the effect of R&D investment on performance. The findings provide evidence that organizational composition plays a moderating role between R&D investment and performance. Finally, this study discusses policy implications, its limitations, and also highlights future research directions.