• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1573-1582
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• 2015

In lifetime data analysis, it is generally known that the lifetimes of test items may not be recorded exactly. There are also situations wherein the withdrawal of items prior to failure is prearranged in order to decrease the time or cost associated with experience. Moreover, it is generally known that more than one cause or risk factor may be present at the same time. Therefore, analysis of censored competing risks data are needed. In this article, we derive the Bayes estimators for the entropy function under the exponential distribution with an unknown scale parameter based on multiply Type II censored competing risks data. The Bayes estimators of entropy function for the exponential distribution with multiply Type II censored competing risks data under the squared error loss function (SELF), precautionary loss function (PLF) and DeGroot loss function (DLF) are provided. Lindley's approximate method is used to compute these estimators.We compare the proposed Bayes estimators in the sense of the mean squared error (MSE) for various multiply Type II censored competing risks data. Finally, a real data set has been analyzed for illustrative purposes.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.1
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• pp.45-59
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• 2012

We analyze a transaction mechanism so-called the revenue sharing transaction model and its dynamics in a supply chain with two competing suppliers and a monopolistic retailer when the demand pattern is uncertain and the back-order is allowed in case. We assume that the products by the suppliers are substitutable each other with a certain degree even though their retail prices are different. It is proved that a supplier and the retailer in the supply chain have some room for enjoying the possibility of their increased profits comparing with the present ones by adopting the suggested revenue sharing scheme. Furthermore, such a transaction model is beneficial even to the customers by offering a lower retail price than before. On the contrary, we observe that another supplier which sticks to an existing transaction scheme is supposed to suffer some decrease in its profit as a result.

• Journal of the Korean Society of Food Culture
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• v.24 no.6
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• pp.702-710
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• 2009

The purpose of this study was to identify the competing values leadership of restaurant general managers and to investigate the impact of their competing values leadership on employee job satisfaction and turnover intention. A sample of full-time restaurant employees (n=360, 36% response) completed an e-mail survey. The results showed that among the eight sub-dimensions of competing values leadership roles, the monitor (4.04), producer (4.01), and director (3.99) roles were perceived as the most frequently used leadership styles of managers compared to broker (3.78), innovator (3.83), and mentor (3.91) roles (p <0.001). Additional T-test results suggested that an employees' gender had an influence on how he/she perceived the leadership style of their manager. Male employees were more likely to perceive that the director and mentor roles (4.19) were performed very well by their managers, while female employees perceived that their managers concentrated more on monitor (3.98) and producer (3.96) roles rather than on broker (3.73) and innovator (3.79) roles (p<0.05). It was found that manager competing values leadership had a significant correlation with employee job satisfaction, and the mentor, coordinator, and innovator manager roles explained the relationship with 42.1% based on multiple regression analysis (p<0.001). In further findings, the manager competing values leadership roles had an effect on employee turnover intention. The results of the data were as follows: mentor and facilitator roles promoted a decrease in employee turnover intention and the director role caused employee turnover intention to increase. Ultimately, this study will be useful for restaurant managers to guide the application of appropriate competing values leadership roles in order to strengthen employee job satisfaction and to reduce turnover intention.

• Journal of Korean Institute of Industrial Engineers
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• v.32 no.2
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• pp.120-125
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• 2006

Since Korean government has implemented the "Number Portability System" in the domestic mobile communications market, mobile communication companies have been striving to hold onto existing customers and at the same time to attract new customers. This paper presents a competing risk model that considers the characteristics of a customer in order to predict the customer's life under the "Number Portability System." Three competing risks considered are pricing policy, quality of communication, and usefulness of service. It was observed that the customers who pay more are less sensitive on pricing policy younger people are less sensitive than older people to the quality of communication and women are more sensitive than men to the degree of usefulness of service. We expect that the result of this study can be used as a guideline for effective management of mobile phone customers under the Number Portability System.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.3
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• pp.95-116
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• 2012

The purpose of this paper is to show the effect of information sharing strategy on the supply chain performances. While traditional information sharing models assumed centralized stock information, recent supply chain practices often implement fully shared stock information, where real-time stock information is accessible on retailers. When retailers are competing with each other, this fully shared stock information may incur retailers' strategic order behaviors. Thus, this paper analyzes a simple two-level supply chain consisting of one warehouse and two identical competing retailers where the real time stock information is fully shared. The warehouse uses the traditional echelon stock policy. Under this environment the retailers' reorder decisions are derived using the order risk concept and the retailer competition mechanism is analyzed. Computational results show that the supply chain performace degradation in the fully shared stock information is quite significant, implying the importance of designing information sharing strategies in the supply chain design phase.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.1
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• pp.113-120
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• 1994

A duopoly model is developed in order to examine the effect of imperfect competition on the price-setting behavior of competing providers in a congested market. Multiple Nash price equilibria are found and the implications of such multiple price equilibria are discussed.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.173-184
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• 2002

In order to evaluate the devolatilization models of pulverized coal, various devolatilization models are examined for the numerical analysis of Drop Tube Furnace.The results of analysis are compared with the experimental results. A numerical study was conducted to explore the sensitivities of the predictions to variation of the model parameters. It helps to elucidate the source of the discrepancies. Three different wall temperature conditions of the DTF, 1100, 1300 and $1500^{\circ}C$ were considered in this analysis. Two fuels are U.S.A. Alaska coal and Australia Drayton coal. The results of analysis with constant rate model, single kinetic rate model and two competing rate modes well presented fast volatile matter release in the early devolatilization. However, in the latter devolatilization they did not coincide with experimental results which presented tardy volatile matter release on account of pyrolysis of high molecular substance. On the other hand, the results of analysis with DAEM(Distribute Activation Energy Model) coincided with experiment al results in overall devolatilization.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.163-163
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• 2001

The primary research questions in this paper are why and how competing firms collaborate, not compete, in the virtual marketplace, e.g., B2B marketplace in the Internet environment. In order to answer the questions, we take on a system dynamics simulation approach: we consider two broad e-collaboration strategies: · Exclusive e-business strategy If the firm adopts this strategy, it allocates all of its resources (available for e-business development) to its own e-business capability building only. · Collaborative e-business strategy When the firm adopts a collaborative e-business strategy, it invests not only in its own, but also the industrys e-business capability building. From the system dynamics simulation results, we conclude that e-collaboration pays off in the long run: although it is hard to tell whether the collaborative strategy is better than the exclusive one during the initial period, it is unambiguous that the collaborative e-business strategy Performs much better in the long run. We infer that such collaboration could occur when the firms realize that they benefit from the expansion of the market demand due to their collaboration. That is, in order for such collaboration between competing firms to be sustainable, such collaboration should create more demand in the market so that each company could earn more profit even if it gets less in terms of market share.

• The Journal of Korean Medicine
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• v.34 no.2
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• pp.41-50
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• 2013

Objectives: As a newcomer to the medical tourism industry, Korea needs to differentiate itself from the leading competing countries to vitalize its early-stage medical tourism industry. This study aims to introduce a strategic plan to vitalize the Korean integrated medical tourism so that Korea can differentiate itself from competing countries and create high added value. Methods: The concept and actual conditions of medical tourism and Oriental medical tourism were examined. A plan to differentiate Korea from the competing countries in the medical tourism industry was studied to create high added-value through strategic vitalization of its medical tourism industry. Results: Korean integrated medical tourism must be developed differently from those of other South-East Asian countries in order to strategically promote the cash-cow medical tourism industry. In order to develop such medical tourism, Korean medical practice, which integrates Western and Oriental medicine, is to be developed through mutual understanding and fusion of other disciplines among medical doctors and Oriental medical doctors who are working in local healthcare for health promotion of local residents and disease prevention and control. This will play a key role in developing a unique medical tourism product of Korea by means of strategic alliances as an integrated medicine. Manpower specialized for integrated medicine is to be specially supplied for Oriental medicine-related business lines at city, county and borough levels, among local governments, that are enthusiastically carrying forward Oriental medical tourism with an interest to promoting more active and strategic business development and raise the effectiveness and efficiency of public health centers handling related medical tourism. Manpower specialized for Korean integrated medical tourism is to be specially supplied for the Ministry of Culture, Health and Tourism, a policy control tower to develop and vitalize high value-added fusion (theme) tourism products such as the Korean integrated medical tourism, in order to discover, promote and support Korean integrated medical tourism's differences from existing medical tourism. Conclusions: The differentiated integrated medical tourism that only Korea can offer in a variety of forms, in order to create a key area of high value-added medical tourism, should be strategically vitalized through a liaison between integrated medicine and tourism and the realization of patient-centered health care services with medical technology developed based on mutual understanding of Western and Oriental medicine.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.92-98
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• 2017

The rapid growth of engineering technology and the emergence of systemized and large-scale engineering systems have resulted in complexity and uncertainty throughout the lifecycle activities of engineering systems. This complex and large-scale engineering system consists of numerous components, but system failure can be caused by failure of any one of a number of components. There is a real difficulty in managing such a complex and large-scale system as a part. In order to efficiently manage the system and have high reliability, it is necessary to structure a system with a complex structure as a sub-system. Also, in the case of a system in which cause of failures exist at the same time, it is required to identify the correlation of the components lifetime and utilize it for the design policy or maintenance activities of the system. Competitive risk theory has been used as a theory based on this concept. In this study, we apply the competitive risk theory to the models with combined structure of series and parallel which is the basic structure of most complex engineering systems. We construct a competing risks model and propose a mathematical model of net lifetime and crude lifetime for each cause of failure, assuming that the components consisting a parallel system are mutually dependent. In addition, based on the constructed model, the correlation of cause of failure is mathematically analyzed and the hazard function is derived by dividing into net lifetime and crude lifetime.