• 대한산업공학회지
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• 제36권2호
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• pp.125-137
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• 2010

This study focuses on the problem of scheduling wafer lots of several product families in the deposition workstation in a semiconductor wafer fabrication facility. There are multiple identical parallel machines in the deposition workstation, and two types of setups, record-dependent setup and family setup, may be required at the deposition machines. A record-dependent setup is needed to find optimal operational conditions for a wafer lot on a machine, and a family setup is needed between processings of different families. We suggest two-phase heuristic algorithms in which a priority-rule-based scheduling algorithm is used to generate an initial schedule in the first phase and the schedule is improved in the second phase. Results of computational tests on randomly generated test problems show that the suggested algorithms outperform a scheduling method used in a real manufacturing system in terms of the sum of weighted flowtimes of the wafer lots.

• Industrial Engineering and Management Systems
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• 제7권2호
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• pp.84-92
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• 2008

Scheduling is one of the most important issues in the planning and operation of production systems. This paper investigates a general job shop scheduling problem with reentrant work flows and sequence dependent setup times. The disjunctive graph representation is used to capture the interactions between machines in job shop. Based on this representation, four two-phase heuristic procedures are proposed to obtain near optimal solutions for this problem. The obtained solutions in the first phase are substantially improved by reversing the direction of some critical disjunctive arcs of the graph in the second phase. A comparative study is conducted to examine the performance of these proposed algorithms.

• Journal of Information Processing Systems
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• 제5권4호
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• pp.237-242
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• 2009

The classical vehicle routing problem (VRP) can be extended by including customers who want to send goods to the depot. This type of VRP is called the vehicle routing problem with pickups and deliveries (VRPPD). This study proposes a novel way to solve VRPPD by introducing a two-phase heuristic routing algorithm which consists of a clustering phase and uses the geometrical center of a cluster and route establishment phase by applying a two-way search of each route after applying the TSP algorithm on each route. Experimental results show that the suggested algorithm can generate better initial solutions for more computer-intensive meta-heuristics than other existing methods such as the giant-tour-based partitioning method or the insertion-based method.

• 산업경영시스템학회지
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• 제38권2호
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• pp.91-100
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• 2015

In this study, we propose an efficient two-phase heuristic policy, called an acceptance tolerance control policy, for Infrastructure as a Service (IaaS) cloud services that considers both the service provider and customer in terms of profit and satisfaction, respectively. Each time an IaaS cloud service is requested, this policy determines whether the service is accepted or rejected by calculating the potential for realizing the two performance objectives. Moreover, it uses acceptance tolerance to identify the possibility for error with the chosen decision while compensating for both future fluctuations in customer demand and error possibilities based on past decisions. We conducted a numerical experiment to verify the performance of the proposed policy using several actual IaaS cloud service specifications and comparing it with other heuristics.

• Computers and Concrete
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• 제32권4호
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• pp.399-410
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• 2023

This study proposes a novel use of backpropagated Levenberg-Marquardt neural networks based on computational intelligence heuristics to comprehend the examination of hybrid nanoparticles on the flow of dusty liquid via stretched cylinder. A two-phase model is employed in the present work to describe the fluid flow. The use of desulphated nanoparticles of silver and molybdenum suspended in water as base fluid. The mathematical model represented in terms of partial differential equations, Implementing similarity transformationsis model is converted to ordinary differential equations for the analysis . By adjusting the particle mass concentration and curvature parameter, a unique technique is utilized to generate a dataset for the proposed Levenberg-Marquardt neural networks in various nanoparticle circumstances on the flow of dusty liquid via stretched cylinder. The intelligent solver Levenberg-Marquardt neural networks is trained, tested and verified to identify the nanoparticles on the flow of dusty liquid solution for various situations. The Levenberg-Marquardt neural networks approach is applied for the solution of the hybrid nanoparticles on the flow of dusty liquid via stretched cylinder model. It is validated by comparison with the standard solution, regression analysis, histograms, and absolute error analysis. Strong agreement between proposed results and reference solutions as well as accuracy provide an evidence of the framework's validity.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.159-166
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• 2006

The aim of synchronization of production and transportation planning in the supply chain is to increase the flexibility and to decrease various costs. The suggested model in this study synchronizes the timing to supply to a downstream manufacturer directly after production and to be consumed in a downstream manufacturer right after receipt. This model deals with the frequent delivery in small amount which is a new trend of the transportation not governed the economy of scale principle. Moreover, various types of transportation governed by the economy of scale principle or not are considered. Then, the two-phase mathematical model is suggested to obtain optimal job sequence and production quantity for each tasks. But, it is difficult to gain optimal solutions if there is a transportation governed by the economy of scale principle in the supply chain, or the size of the problem is increased. Thus, heuristic algorithms based on simulated annealing and genetic algorithm are suggested to find good solutions in the reasonable time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권4호
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• pp.1276-1295
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• 2023

Sensor networks are now an essential aspect of wireless communication, especially with the introduction of new gadgets and protocols. Their ability to be deployed anywhere, especially where human presence is undesirable, makes them perfect choices for remote observation and control. Despite their vast range of applications from home to hostile territory monitoring, limited battery power remains a limiting factor in their efficacy. To analyze and transmit data, it requires intelligent use of available battery power. Several studies have established effective routing algorithms based on clustering. However, choosing optimal cluster heads and similarity measures for clustering significantly increases computing time and cost. This work proposes and implements a simple two-phase technique of route creation and maintenance to ensure route reliability by employing nature-inspired ant colony optimization followed by the fuzzy decision engine (FDE). Benchmark methods such as PSO, ACO and GWO are compared with the proposed HRCM's performance. The objective has been focused towards establishing the superiority of proposed work amongst existing optimization methods in a standalone configuration. An average of 15% improvement in energy consumption followed by 12% improvement in latency reduction is observed in proposed hybrid model over standalone optimization methods.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제11권1호
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• pp.1-14
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• 2005

컨포넌트 개발 프로세스에서 재사용 가능한 독립적인 컴포넌트의 식별은 가장 중요한 작업이면서 어려운 작업이다. 따라서 현존하는 컴포넌트 개발 방법론들에서는 컴포넌트 식별을 위해서 체계적이고 명확한 기준이 제시되지 않아 대다수 개발자의 직관과 경험에 의존하고 있다. 그 결과 평이한 개발자에 의해서 소프트웨어의 재사용 단위인 컴포넌트를 식별하기가 쉽지 않다. 따라서 본 논문에서는 컴포넌트를 용이하게 식별할 수 있도록 유스케이스 다이어그램, 클래스 다이어그램 그리고 시퀀스 다이어그램 등 도메인 모델을 기반으로 컨포넌트를 식별하는 기준과 방법을 제시한다. 본 논문에서는 2단계 즉, 시스템 컨포넌트 식별과 비즈니스 컴포넌트 식별을 통하여 컴포넌트론 식별하는 방법을 제시한다. 특히, 제안된 기법에서는 컴포넌트 식별에 있어서 구조적 특성뿐만 아니라 메소드 호출 유형과 방향에 따른 의존성 특성을 함께 괴려하고 있다 이러한 제안된 기법의 실용성을 검증하기 위해 사례 연구와 기존 식별 방법과의 비교 분석 및 평가를 제시한다.