• ETRI Journal
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• v.34 no.4
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• pp.492-502
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• 2012

We consider an overlaid broadcast service, where a spread spectrum (SS)-based broadcast signal is overlaid onto the existing terrestrial Digital Multimedia Broadcasting (T-DMB) band. The system is similar to the augmented data transmission in the ATSC DTV, for which it was investigated mostly in terms of link level performance, such as bit error rate. Our focus in this paper is on the system-level performances. More specifically, utilizing both a large scale path loss and a small scale fading channel model, the primary objective is to explore the tradeoff between the coverage and the achievable rate of the overlaid service and, finally, to determine the achievable rate in the overlaid service for marginal coverage reduction in the existing broadcast service. The analytical and simulation results show that an SS-based add-on service of 10 kbps to 20 kbps can co-exist with the T-DMB service while resulting in only a marginal degradation in T-DMB coverage (for example, less than one percent reduction).

• Journal of Korea Multimedia Society
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• v.11 no.12
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• pp.1730-1738
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• 2008

Quality of Service (QoS) Guarantees grant ways for service providers to establish service differentiation among subscribers. On the other hand, service subscribers are also assured the level of service they paid for. In addition, the efficient level of service quality can be selected according to the subscribers' needs thus ensuring efficient use of available bandwidth. While network utility optimization techniques assure certain QoS metrics, a number of situations exist where some QoS goals are not met. The optimality of the network parameters is not mandatory to guarantee specified QoS levels. This paper proposes a joint data rate and power control scheme that guarantees service contract QoS level to a subscriber using Goal Programming. In using goal programming, this paper focuses on finding the range of feasible solutions as opposed to solving for the optimal. In addition, in case no feasible solution is found, an acceptable compromised solution is solved.

• Journal of the East Asian Society of Dietary Life
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• v.16 no.6
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• pp.753-762
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• 2006

The purpose of this research is to analyze the importance and satisfaction level with the service of Korean restaurants for Japanese and Chinese students in Korea. Self adminstered guestionnaires were collected from 204 Japanese and Chinese students in Korea. The data was statistically analysed using t-tests, one-way ANOVA, reliability test, factor analysis and regression test. The average values of importance-factor and satisfaction-factor were significantly different. Based on analyses of the 20 service level factors, satisfaction level was significantly lower than importance level. Satisfaction-factors such as quality of food, hygiene of restaurant and employees, service level, and atmospheres, significantly influenced the overall satisfaction level of Korean food and restaurants.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.42
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• pp.21-30
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• 1997

This research fundamentally deals with an analysis of service level for a multi-level inventory distribution system which is consisted of a central distribution center and several branches being supplied stocks from the distribution center, Under continuous review policy, the distribution center places an order for planned order quantity to an outside supplier, and the order quantity is received after a certain lead time. Also, each branch places an order for particular quantity to its distribution center, and receives the order quantity after a lead time. In most practical distribution environment, demands and lead times are generally not fixed or constant, but variable. And these variabilities make the analysis more complicated. Thus, the main objective of this research is to suggest a method to compute the service level at each depot, that is, the distribution center and each branch with variable demands and variable lead times. Further, the model will give an idea to keep the proper level of safety stocks that can attain effective or expected service level for each depot.

• Journal of the Korea Safety Management & Science
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• v.3 no.3
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• pp.65-75
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• 2001

This research fundamentally deals with an analysis of service level for a multi-level inventory distribution system which is consisted of a central distribution center and several branches being supplied stocks from the distribution center, Under continuous review policy, the distribution center places an order for planned order quantity to an outside supplier, and the order quantity is received after a certain lead time. Also, each branch places an order for particular quantity to its distribution center, and receives the order quantity after a lead time. In most practical distribution environment, demands and lead times are generally not fixed or constant, but variable. And these variabilities make the analysis more complicated. Thus, the main objective of this research is to suggest a method to compute the service level at each depot, that is, the distribution center and each branch with variable demands and variable lead times. Further, the model will give an idea to keep the proper level of safety stocks that can attain effective or expected service level for each depot.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.23 no.2
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• pp.271-294
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• 2012

This study is designed to evaluate the service quality of public libraries according to managing entities by LibQUAL+ and to devise ways to improve problems based on comparison and analysis of the differences in the service qualities. To achieve this, four public libraries in Seoul according to the managing entities were investigated. They consisted of libraries of public corporations, cultural centers, foundations and universities. Minimum service quality level, desired service quality level and perceived service quality was analyzed based on nine-point Lickertis scale. A survey was employed and consisted of twenty-two items. The results showed that current level of service met the minimum level, yet failed to reach their desired service level. The study suggested that public libraries contracting out to private sector need to actively apply users' demands and the changing environment of libraries, and continue to strive to provide public library users with high quality service through efforts of evaluating and improving the services for their users.

• Korean Management Science Review
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• v.28 no.3
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• pp.15-29
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• 2011

In this paper, we consider a system working at both primary service and secondary service. A server can switch between the primary service and the secondary service or it can be assigned to secondary service as a dedicated server. A service policy is characterized by the number of servers dedicated to the secondary service and a rule for switching the remaining servers between two services. The primary service system is modelled as a Markovian queueing system and the throughput is a function of the number of servers, buffer capacity, and service policy. And the secondary service system has a service level requirement strategically determined to perform the service assigned. There is a revenue obtained from throughput and costs due to servers and buffers. We study the problem of simultaneously determining the optimal total number of servers, buffers, and service policy to maximize profit of the system subject to both an expected customer waiting time constraint of the primary service and a service level constraint of the secondary service and develop an algorithm which can be successfully applied with the small number of computations.

• Journal of Information Technology Services
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• v.9 no.1
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• pp.57-71
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• 2010

The purpose of this study is to verify the competence level of IT service companies in Korea from the view point of capability of creating customers value and outcome as an independent companies which have been growing in the captive customers(market) circumstance by performance data analysis and IT specialists survey. This study presents a growth model which emphasis on the importance of the correlation between IT service companies and captive customers. It proves that the captive customers have been being the growth power and motive of the IT service company, because IT service companies have been cumulating the competence for IT service through the service for the customers, and with this competence, IT service companies have been expanding its service out to non-captive market(customers) and got good outcomes as an independent companies. And this study proves that the captive customers who served by the IT service companies which have a higher level of service capabilities have better business outcome. IT service companies contribute to improve the IT level of the captive customers and to make the customers to increase sales by conducting IT projects.

• Korean Journal of Social Welfare
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• v.64 no.4
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• pp.137-161
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• 2012

The importance of voucher service evaluation is increasing with the expansion of voucher, but the previous studies on performance evaluation could not reflect the characteristics of voucher. But there is no study on the factors affecting voucher performance. Thus, this study focuses on the empirical analysis of voucher program performance and analysed the factors affecting voucher satisfaction. Data used in this study is collected form 70 social service agencies that deliver voucher service and 1445 service users in Community-Development voucher service in Community Service Investment Program. The methods applied in this study are Hierarchial Linear Model(HLM) using service user variables(level 1) and service agency variables(level 2). These variables are extracted from the previous studies on performance of social welfare service and voucher service. The findings show that user's satisfaction is influenced by level 1 variables such as sex, need and also influenced by level 2 variables of service type and area* organization type. On these analysis, this study gives policy implication.

• Korean Journal of Occupational Health Nursing
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• v.21 no.2
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• pp.145-153
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• 2012

Purpose: The purpose of this study was to verify influencing factors on service quality provided by care helpers working for the elderly in long term care. Methods: The data were collected using self-reported questionnaire from 221 care helpers working in long-term care facility or home care service center. The data were analyzed using multiple regression with the SPSS/WIN 17.0 program. Results: There were significant differences in service quality depending on the health status, intimacy level, pleasure level, job education, and turnover intention. Factors influencing service quality were gender, intimacy level with elderly, type of working place and job satisfaction with $R^2$ value of 17.3%. The most influencing factor was intimacy level (${\beta}$=.249), followed by job satisfaction (${\beta}$=.208), gender (${\beta}$=.170), and type of working place (${\beta}$=.146). Conclusion: The results of this study indicate that the effort to improve the service quality of care helper should be focused on helping intimacy building between the elderly and the care helper. Also, a more effective way to improve service quality would be intervening for care helpers providing institutional care.