• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2297-2311
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• 1994

This paper presents the study on the development of a DNC, system IPIS(Interactive Plant Information System)/DNC, which can manage NC machines and robots as a distributed control method in the machine. processing factory. The IPIS/DNC system is composed of a host computer, satellites and NC machines. A set of software modules are developed on the host computer and the satellites separately. By modularizing each functions of the IPIS/DNC system and using multi-taking method, the functions such as NC program management, NC program distribution, and shop monitoring can be performed on the host computer, and the functions such as NC program transfer to the NC machines, and NC program editing can be performed on the satellites. A Relational database which is linked with job scheduling system is used for IPIS/DNC system.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.107-110
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• 2000

화학 박막 증착용(CVD : Chemical Vapor Deposition) 클러스터 장비는 다양한 공정 경로가 가능하며 물류 흐름이 매우 복잡해질 수 있다. 또한, 공정이 종료된 웨이퍼는 제한 시간 내에 챔버에서 꺼내져야만 한다. 클러스터 장비는 두 개의 팔을 가진 로봇이며, 빈 쪽 팔을 이용하여 공정이 종료된 웨이퍼를 꺼낸 후, 다른 쪽 팔을 이용하여 이전 공정에서 가져온 웨이퍼를 해당 공정에 넣어 주는 스왑(SWAP) 방식으로 운영된다. 이러한 스왑 방식에서는 로봇 작업 순서가 결정되어 진다. 그러나, 로봇의 팔 이외에 임시버퍼가 없고, 각 챔버는 엄격한 체제 시간 제약(Residency Time Constraint)을 가지고 있기 때문에 로봇의 작업 시점의 제어가 필요하다. 본 논문에서는 간단한 Earliest Starting 방식으로 로봇의 작업 시점을 제어한다고 가정했을 때, 스왑 방식을 운용하면서 체제 시간 제약을 만족하는 공정 시간들의 조건을 제시한다. 공정 시간은 엔지니어에 의해 다소 조정이 가능하므로 공정 시간들의 조건은 엔지니어에게 스케줄 가능한 공정 시간을 결정할 수 있도록 지원해 주는 시스템에 활용 가능하다. 또한, 본 논문에서는 FSM(Finite State Machine)을 이용하여 CTC(Cluster Tool Controller) 내부의 실시간 스케줄러 구현 방법을 제안한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.371-374
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• 1997

This study presents a new type of real-t~me CNC interpolator that is capable of generating cutter paths for ball-end milling of NURBS surfaces. The proposed surface interpolator comprises real-time algorithms for cutter-contact (CC) path scheduling and CC path interpolation. Especially, in this study, a new interpolator module to regulate cutting forces is developed. This proposed algorithm utilizes variable-feedrate commands according to the curvature of machined surfaces. The proposed interpolator is evaluated and compared with the conventional method based on constant feedrates through computer simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.154-158
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• 1997

This paper proposes a new resource allocation system where overall performance can be improved using production smoothing method. In economic point of view, market price is determined by the market mechanism that is subject to the law of demand and supply. Similarly, agents determine whether to allocate tasks to machines by profit and loss or not. In existing resource allocation system, tasks are exclusively allocated to agents with better manufacturing conditions, because they are evaluated by the only currency. But in the proposed resource allocation system, agents are evaluated by not only a currency but also machine specifications. Hereby, the production smoothing is achieved and we expect to improve system performance In this study, we propose a resource allocation system with consideration of Production Smoothing.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1991.10a
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• pp.77-89
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• 1991

One of the important problems concerning the efficient operation of an automated manufacturing system is the flow control problem. Most research papers about scheduling and control of a FMS consider fabrication, machining and assembly independently. In this paper an effective flow control strategy for a FMS with an assembly subsystem which may be called FMAS (Flexible Machining and Assembly System) is designed using the operation-oriented and, combined Push and Pull control method. The flow control system to be described here could meet production demands with a minimum makespan while satisfying assigned due-dates and keeping a low volume of work-in-process at the same time. The control mechanism also considers machine failures and rush jobs.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.2
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• pp.183-192
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• 2000

This paper considers the problem of scheduling a set of n jobs on m parallel machines to minimize total weighted tardiness. For the problem a genetic algorithm is proposed, in which solutions are encoded using the random key method suggested by Bean and new crossover operators are employed to increase performance of the algorithm. The algorithm is compared with the Modified Due-Date (MDD) algorithm after series of tests to find appropriate values for genetic parameters. Results of computational tests on randomly generated test problems show that the suggested algorithm performs better than the MDD algorithm and gives good solutions in a reasonable amount of computation time.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.566-569
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• 2004

본 연구에서는 생산능력의 제한이 있는 다계층(multi-echelon) 공급사슬에서의 효과적인 분배계획수립을 목적으로 한다. 수요 정보는 계획 기간(planning horizon) 동안 확정적인 형태로 주어지고 이러한 상황 하에서 전체 공급사슬에서 발생하는 재고유지 비용(holding cost)과 재고이월 비용(backorder cost)의 합을 최소화하는 분배 문제의 해법을 제시하고자 한다. 본 연구에서는 총비용을 최소화하는 각 노드별 분배량을 결정하기 위해서 look-ahead 기법을 사용한다. Look-ahead 기법을 통해 분배 계획 수립 시 해당 기간의 수요 정보뿐만 아니라 미래 수요를 함께 반영함으로써 생산능력 제한에 효과적으로 대처할 수 있도록 하였다. Look-ahead 기법을 적용하기 위해 본 문제를 단일 기계 일정계획(single machine scheduling) 문제로 전환하고 이에 대한 효율적인 발견적 기법을 제시한다. 또한 제안된 발견적 기법의 성능을 평가하기 위해 다양한 실험 조건하에서 제안된 알고리듬과 기존의 미래 수요를 고려하지 않는 계층 재고 정책(echelon stock policy)의 결과를 비교하여 본 연구의 우수성을 입증하였다.

• Korean Management Science Review
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• v.24 no.1
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• pp.35-43
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• 2007

Minimizing the total number of setup changes of a machine increases the throughput and improves the stability of a production process, and as a result enhances the product qualify. In this context, we consider a new product-mix problem that minimizes the total number of setup changes while producing the required quantities of a product over a given planning horizon. For this problem, we develop a mixed integer programming model. Also, we develop an efficient heuristic algorithm to find a feasible solution of good quality within reasonable time bounds. Computational results show that the developed heuristic algorithm finds a feasible solution as good as the optimal solution in most test problems.

• Industrial Engineering and Management Systems
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• v.14 no.4
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• pp.401-412
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• 2015

In this paper, we present a modeling approach to production planning for an actual production line and a heuristic method. We also illustrate the successful implementation of the proposed method on the production line. A heuristic algorithm called the push-back algorithm was designed for a single machine earliness/tardiness production planning with distinct due date. It was developed by combining a minimum slack time rule and shortest processing time rule with a push-back procedure. The results of a numerical experiment on the heuristic's performance are presented in comparison with the results of IBM ILOG CPLEX. The proposed algorithm was applied to an actual case of production planning at Woongjin Chemical, a leading manufacturer of filter products in South Korea. The seven-month execution of our algorithm led to a 24.5% decrease in the company's inventory level, thus demonstrating its practicality and effectiveness.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.01a
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• pp.87-88
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• 2018

본 논문에서는 IIoT 환경에서 중요한 비정상적 데이터 수집을 위한 노드 우선순위 선정 모델을 제안하였다. 제안하는 모델은 비정상적 데이터 수집과 다른 노드로 부터의 정상 데이터의 수집 격차를 적절히 조절하기 위하여 Fair and Delay-aware Cross-layer(FDRX) 기법과 데이터 Classification 기법을 이용, 데이터의 긴급성과 네트워크 환경을 분석하여 노드를 평가한다. 이를 통하여 IIoT 환경에서의 데이터 분석에 중요한 비정상적 데이터를 원활하게 수집하면서도 다른 노드와의 전송 격차를 줄일 수 있을 것으로 기대된다.