• Industrial Engineering and Management Systems
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• v.15 no.2
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• pp.131-142
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• 2016

We consider a multi-server queueing system without buffer and with two types of customers as a model of operation of a mobile network cell. Customers arrive at the system in the marked Markovian arrival flow. The service times of customers are exponentially distributed with parameters depending on the type of customer. A part of the available servers is reserved exclusively for service of first type customers. Customers who do not receive service upon arrival, can make repeated attempts. The system operation is influenced by random factors, leading to a change of the system parameters, including the total number of servers and the number of reserved servers. The behavior of the system is described by the multi-dimensional Markov chain. The generator of this Markov chain is constructed and the ergodicity condition is derived. Formulas for computation of the main performance measures of the system based on the stationary distribution of the Markov chain are derived. Numerical examples are presented.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.277-280
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• 2006

Most real world design evaluation and risk-based decision support combine quantitative and qualitative (linguistic) variables. Decision-making based on conventional mathematics that combines qualitative and quantitative concepts always exhibit difficulty in modelling actual problems. The successful selection process for choosing a design/procurement proposal is based on a high degree of technical integrity, safety levels and low costs in construction, corrective measures, maintenance, operation, inspection and preventive measures. However, the objectives of maximising the degree of technical performance, maximising the safety levels and minimising the costs incurred are usually in conflict, and the evaluation of the technical performance, safety and costs is always associated with uncertainties, especially for a novel system at the initial concept design stage. In this paper, a design-decision support framework using a composite structure methodology grounded in approximate reasoning approach and evidential reasoning method is suggested for design evaluation of machinery space of a ship engine room at the initial stages. It is a Multiple Attribute Decision-Making (MADM) or Multiple Criteria Decision Making (MCDM) framework, which provides a juxtaposition of cost, safety and technical performance of a system during evaluation to assist decision makers in selecting the winning design/procurement proposal that best satisfies the requirement in hand. An illustrative example is used to demonstrate the application of the proposed framework.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.357-361
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• 2022

Employing the available technologies and utilizing the advanced means to improve the level of health care provided to citizens in their various locations. Citizens have the right to get a proper health care services despite the location of their residency or the distance from the health care delivery centers, a goal that can be achieved by utilizing air ambulance systems. In such systems, aircrafts and their life spans are the essential component, the flight duration of the aircraft during its life span is determined by the maintenance schedule. This research, enhances the air ambulance systems by presenting a proposal that maximizes the aircraft flight duration during its life span. The enhancement will be reached by developing a set of algorithms that handles the aircraft maintenance problem. The objective of these algorithms is to minimize the maximum completion time of all maintenance tasks, thus increasing the aircraft operation time. Practical experiments performed to these algorithms showed the ability of these algorithms to achieve the desired goal. The developed algorithms will manage the maintenance scheduling problem to maximize the uptime of the air ambulance which can be achieved by maximizing the minimum life of spare parts. The developed algorithms showed good performance measures during experimental tests. The 3LSL algorithm showed a higher performance compared to other algorithms during all performed experiments.

• Journal of Ocean Engineering and Technology
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• v.36 no.3
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• pp.168-180
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• 2022

The IMO has decided to proceed with the early introduction of EEDI Phase 3, a CO₂ emission regulation to prevent global warming. Measures to reduce CO₂ emissions for ships that can be applied immediately are required to achieve CO₂ reduction. We set six different CO₂ emission scenarios according to the type of ship and fuel, and designed a monoethanolamine-based CO₂ capture process for ships using a rate-based model of Aspen Plus v10. The simulation model using Aspen Plus was validated using pilot plant operation data. A ship inevitably tilts during operation, and the performance of a tilted column decreases as its height increases. When configuring the conventional CO₂ capture process, we considered that the required column heights were so high that performance degradation was unavoidable when the process was implemented on a ship. We applied a parallel column concept to lower the column height and to enable easy installation and operation on a ship. Simulations of the parallel column confirmed that the required column height was lowered to less than 3 TEU (7.8 m).

• Journal of Korea Water Resources Association
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• v.47 no.2
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• pp.195-206
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• 2014

In this study, a performance evaluation method of water supply for a multi-purpose dam based on deficitsupply method and reservoir storage is presented. The method is applied to 16 multi-purpose dams and water supply performance is evaluated. As a result, 6 dams (Soyanggang, Chungju, Hoengseong, Andong, Imha, and Hapcheon dam) have highest performance and 2 dams (Sumjingang and Buan dam) have relatively low performance. Particularly, Buan dam is the most vulnerable in the analysis results of reliability, resiliency, and vulnerability. Therefore, measures to improve the performance of water supply are needed in Buan multi-purpose dam.

• Journal of Distribution Science
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• v.12 no.12
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• pp.119-130
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• 2014

Purpose - Franchise industries are significant both socially and economically. However, with increasing interest, there are manifold problems. It is necessary to seek measures for mature operation constantly despite unprepared franchisors, negative perceptions of the media and society toward franchise, and rapid changes in business start-up trends and propensity to consume that make business start-ups difficult. The paper aims to explain the effects of relational commitment and performance on the franchisor's management characteristics and justice in the food service franchise system. Research design, data, and methodology - This is an exploratory survey examining franchising in Korea. Based on a literature synthesis, we extract five constructs: managerial characteristics, support, fairness, trust, and satisfaction. We hypothesize that these factors influence the trust, satisfaction, and performance of franchisees. To examine these hypotheses empirically, we conducted a survey on the database of the Franchising Council of Korea. The study employs data from May to September 2014. In total, 135 completed questionnaires were received, of which 128 were usable. The data was analyzed with SPSS/PC 22.0. First, to test unidimensionality and nomological validity of the measures of each construct, we employed a scale refinement procedure. The result of a reliability test with Cronbach's α and factor analysis warranted unidimensionality of the measures for each construct. In addition, nomological validity of the measures was warranted from the result of the correlation and regression analysis. By analyzing the data, we can confirm most hypotheses. Results - Frist, franchisor characteristics have a positive effect on trust and satisfaction. Second, franchisor fairness has an effect on trust and satisfaction. Third, franchisor support has an effect on satisfaction. Further, the franchisee trust has an effect on satisfaction. Fourth, the satisfaction of a franchisee with a franchisor affects the performance of a franchisee. Finally, there is a possibility that not only franchisee performance but also increasing the credibility and improving the image of the franchisor through communication between franchisor and franchisee can improve franchisees' performance and satisfaction by motivating the franchisee for sustainable growth. Franchisers should endeavor for franchisees to obtain stable revenue with continuous and practical support. They should recognize that they can expand their business by supporting their franchisees. Franchisors should not only instantly respond to franchisees' troubles with interactive communications but also raise the ability of supervisors for better support. Franchisors should share their visions and goals with their franchisees and provide systematic and continuous support based on trust and clear company management. Franchisees should understand franchisors' position as well as participate in establishing the basic franchise system. Contributions - The paper contributes to understanding franchising in Korea. It offers insights and assistance to franchisors hoping to start franchises. This paper explores measurement issues related to franchisee performance by estimating its determinant factors (managerial characteristics, support, fairness, trust, and satisfaction). This study provides franchisors and practitioners planning to extend their franchising business with some practical knowledge.

• Journal of the military operations research society of Korea
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• v.17 no.2
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• pp.90-99
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• 1991

In this paper a dispatching rule, $D^{*}$, for AGV operations in automated manufacturing system is proposed to improve the performance measures. And the algorithm is compared with existing heuristic rules via simulation to evaluate its capabilities. It is shown that the proposed rule enhances mean flow time, makespan and throughput, and avoids the locking phenominon which can be fatal to the operation of automated manufacturing systems.

• Proceedings of the KOR-KST Conference
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• 2002.02a
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• pp.143-159
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• 2002

The performance of two single-barrier three-phase actuated control systems at diamond interchanges was evaluated for various traffic conditions. To emulate the actuated signal control, hardware-in-the-loop system combined with CORSIM simulation program was used. Two performance measures, average delay and total stops, were used for the evaluation process. Results showed that the two three-phase systems gave similar performance in terms of average delay, but not stops. The delay performance of each phasing system was generally dependent on the traffic pattern and ramp spacing. The total stops decreased as the spacing increased, and it was the most sensitive variable that can differentiate between the two three-phase systems. It was also shown that the hardware-in-the-loop control could provide a good method to overcome the limitations of current simulation technology.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1263-1266
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• 1997

In a fault-tolerant modern manufacturing systms characterized by the configuration, in which automated redundant machines prone to unexpected failures are interconnected with other complex subsystems such as AGV's, robots, computer control systems to produce complete parts, faulures together with repairs and reconfigurations should be considered as the three basic events to be modeled for computing the performance of manufacturing systems. In this papre, transient analysis is applied to modular cell manufacturing systems form a performability viewpoint whose modeling adantage is that various performanc e measures can be evaluated compositely in the context of application. The hypothertical modular cells are modeled firstly with hybrid decomposition method and availability measures as special cases of performability are computed and comments on performabililty modeling analysis are mentioned.

• Journal of Navigation and Port Research
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• v.34 no.7
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• pp.595-601
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• 2010

This paper aims to diagnose the strategy execution ability and to provide corresponding measures for Korean oceanic shipping companies. The analysis method is the t-test between importance awareness and Corresponding ability for strategy execution diagnosis index(XPP). According to the diagnosed results, the strategy development is unsatisfactory because the strategy implemented does not adhere to concurrent environmental change. Moreover, the execution of the strategy is also unsatisfactory. Therefore, an evaluation shows that there is a need for a SWOT analysis using BSC, an organization structure to strengthen the strategy execution ability and the support from the market condition analysis prediction center.