• 대한산업공학회지
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• 제34권3호
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• pp.318-327
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• 2008

This paper considers a single-machine scheduling problem with availability constraints. In many realistic situations, machines may not be always available due to various reasons such as maintenance, breakdown and repair. However, most literature on scheduling assume that the machines are available at all times. This paper deals with a single-machine scheduling problem with periodic maintenance. If the maintenance decision is made jointly with the job scheduling, the system will be more effective. The objective is to minimize the total completion time of jobs. This problem is proved to be NP-hard in the strong sense. The proposed breaking heuristic(BH) algorithm rule is established by some theorems and conditions. Our computational results show that the BH algorithm is much more efficient than existing heuristic.

• 대한수학회보
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• 제52권6호
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• pp.1945-1962
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• 2015

This paper is mainly concerned with the formation of delta standing wave for the scalar conservation law with a linear flux function involving discontinuous coefficients by using the self-similar viscosity vanishing method. More precisely, we use the self-similar viscosity to smooth out the discontinuous coefficient such that the existence of approximate viscous solutions to the delta standing wave for the Riemann problem is established and then the convergence to the delta standing wave solution is also obtained when the viscosity parameter tends to zero. In addition, the Riemann problem is also solved with the standard method and the instability of Riemann solutions with respect to the specific small perturbation of initial data is pointed out in some particular situations.

• 품질경영학회지
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• 제37권2호
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• pp.68-77
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• 2009

There are many quality control(QC) tools useful for solving quality problems. In this paper, QC 7 tools, new QC 7 tools, and other quality tools are first compared with respect to their frequency of use. We suggest an integrated problem-solving procedure to systematically deal with various quality problems. For each step a streamlined flow chart is presented to help the practitioners to adopt relevant tools depending on certain situations they face. The procedure will help quality practitioners solve field quality problems.

• Industrial Engineering and Management Systems
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• 제15권4호
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• pp.354-363
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• 2016

Due to uncertain environment, various parameters such as price, queuing length, warranty, and so on influence on inventory models. In this paper, an inventory-queuing-pricing problem with continuous review inventory control policy and batch arrival queuing approach, is presented. To best of our knowledge, (I) demand function is stochastic and price dependent; (II) due to the uncertainty in real-world situations, a fuzzy programming approach is applied. Therefore, the presented model with goal of maximizing total profit of system analyzes the price and order quantity decision variables. Since the proposed model belongs to NP-hard problems, Pareto-based approaches based on non-dominated ranking and sorting genetic algorithm are proposed and justified to solve the model. Several numerical illustrations are generated to demonstrate the model validity and algorithms performance. The results showed the applicability and robustness of the proposed soft-computing-based approaches to analyze the problem.

• 한국정보처리학회논문지
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• 제7권3호
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• pp.953-961
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• 2000

In this paper, we propose the algorithm which solve synchronization problem happened migrating service objects. Load imbalance is occurred due to allocate different amount of load to be proposed to each node in distribute system. To solve this problem, the service objects have to be migrated from heavily loaded node to lightly loaded node. And in such a process, the synchronization problem may occur when client request a service object migrated incompletely. Therefore, we describe the environment of executing service objects, the importer/exporter/trader model compatible with migration of service objects, and appropriate migration algorithm, Finally, we analyze the conditions of problems, and propose the solution of each situations. Also, the performance advantages of using proposed algorithms are quantified through a simulation study.

• East Asian mathematical journal
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• 제38권4호
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• pp.379-396
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• 2022

In this paper, we investigate distribution strategies in the Egyptian fraction, and through this, we examine the distribution strategies of (fraction)÷(fraction) and then provide some educational implications. The (natural number)÷(natural number) of the sharing situation has the meaning of 'share' per unit, which can be seen as a situation where the unit ratio is determined. These concepts can also naturally be extended to the case of (fraction)÷(fraction) by some problem posing situations. That is to say, the case of (fraction)÷(fraction) can be deduced the case (natural number)÷(natural number) by the re-statement of the problem.

• Journal of Information Processing Systems
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• 제18권3호
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• pp.389-401
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• 2022

The business of Internet of Vehicles (IoV) is growing rapidly, and the large amount of data exchange has caused problems of large mobile network communication delay and large energy loss. A strategy for resource allocation of IoV communication based on mobile edge computing (MEC) is thus proposed. First, a model of the cloud-side collaborative cache and resource allocation system for the IoV is designed. Vehicles can offload tasks to MEC servers or neighboring vehicles for communication. Then, the communication model and the calculation model of IoV system are comprehensively analyzed. The optimization objective of minimizing delay and energy consumption is constructed. Finally, the on-board computing task is coded, and the optimization problem is transformed into a knapsack problem. The optimal resource allocation strategy is obtained through genetic algorithm. The simulation results based on the MATLAB platform show that: The proposed strategy offloads tasks to the MEC server or neighboring vehicles, making full use of system resources. In different situations, the energy consumption does not exceed 300 J and 180 J, with an average delay of 210 ms, effectively reducing system overhead and improving response speed.

• Journal of applied mathematics & informatics
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• 제41권3호
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• pp.553-567
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• 2023

There are real life situations in our lives where the things are changing continuously or from time to time. It is a very important problem for one whether to continue the existing relationship or to form a new one after some occasions. That is, people, companies, cities, countries, etc. may change their opinion or position rapidly. In this work, we think of the problem of changing relationships from a mathematical point of view and think of an answer. In some sense, we comment these changes as power changes. Our number theoretical model will be based on this idea. Using the convolution sum of the restricted divisor function E, we obtain the answer to this problem.

• 대한안전경영과학회지
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• 제25권2호
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• pp.1-8
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• 2023

This paper is proposing a novel machine scheduling model for the unrelated parallel machine scheduling problem without setup times to minimize the total completion time, also known as "makespan". This problem is a NP-complete problem, and to date, most approaches for real-life situations are based on the operator's experience or simple heuristics. The new model based on the Memetic Algorithm, which was proposed by P. Moscato in 1989, is a hybrid algorithm that includes genetic algorithm and local search optimization. The new model is tested on randomly generated datasets, and is compared to optimal solution, and four scheduling models; three rule-based heuristic algorithms, and a genetic algorithm based scheduling model from literature; the test results show that the new model performed better than scheduling models from literature.

• 한국콘텐츠학회논문지
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• 제22권5호
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• pp.721-733
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• 2022

본 연구의 목적은 코로나-19 상황 속 사례관리자의 실천 경험을 탐색하는 데 있다. 이를 위해 일 지역사회의 다양한 사회복지기관에서 사례관리 업무를 담당하는 사회복지사 6인을 연구참여자로 선정하고 질적연구를 실시하였다. 연구 결과 '위기와 기회의 장', '낯설고 새로운 방식 도입으로 인한 불안과 해소 노력', '클라이언트의 상황 변화에 대응함'이라는 세 개의 주제가 도출되었다. 사례관리자는 비대면이라는 제한적인 상황 속에서도 익숙하지 않은 새로운 방법을 통하여 간접적인 서비스를 제공하고자 노력하였고, 환경에 맞추어 변화하는 클라이언트의 욕구에 대응하기 위해 공적 서비스를 적극적으로 활용하는 방안을 모색하였다. 따라서 본 연구의 의미는 '계속되는 도전에 대한 숨찬 응전 '으로 파악되었다. 앞선 연구 결과를 바탕으로, 현재 '위드 코로나'가 시행되고 있는 현 상황에서 지역사회의 복지 증진을 위해 사례관리자가 갖춰야 하는 역량과 실천 방향을 제시 하였다.