• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.141-151
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• 2013

Process planning can be defined as determining detailed methods by which parts can be manufactured from the initial to the finished stage. Process planning starts with determining the manufacturing process based on the geometric shape of the part and the machines and tools required for performing this process. Distributed process planning enables production planning to be performed easily by combining the extracted process and various manufacturing resources such as operations and tools. This study proposes an algorithm to determine the process for a feature-based model and to combine manufacturing resources for the process and implements a distributed process planning system.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.161-166
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• 1999

Virtual Manufacturing System(VMS) is a computer model that represents the precise and whole structure of manufacturing systems and simulates their physical and logical behavior in operation. In this paper, a real time simulation for the virtual factory is proposed to integrate a process planning with scheduling under distributed environments. In order to communicate the information under distributed environments, we use a server/client concept using socket program and internet.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.11a
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• pp.146-148
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• 2003

Bayer 공정은 가성소다를 이용하여 보오크사이트로부터 수산화알루미늄을 추출하는 공정이다. 그러나 보오크사이트 추출 후 1차 침전공정에서 반응한 보오크사이트 잔사는 침전시킴으로써 깨끗한 공정액을 분리하는 데 이때 침전되지 못한 다량의 분산성 고형물이 공정액 중에 존재하게 되는데 이를 분산성 보오크사이트(레드머드) 미립자라하며 보통 80-100mg/$\ell$의 농도를 나타낸다. 그러므로 이를 제거하기 위해 다음 공정인 입상여과필터 공정을 사용하는데 이때 필터링 효율증대를 위해 보조제로써 다량의 소석회(Ca(OH)$_2$)를 투여하여 공정액 중의 고형물을 농도를 8-100mg/$\ell$에서 5mg/$\ell$로 낮추는 공정을 사용하고 있다. 특히 국내 수산화알루미능 제조회사일 KC(주)의 경우 소석회 사용량이 일 10톤, 년간 약 3,600톤을 사용함으로써 소석회의 사용량에 따라 같은 량의 슬러지가 발생되게 된다. 따라서 여과후 발생되는 슬러지의 처리비용 문제(연간 9천만원)와 소석회의 미립자에 의한 공정액의 2차 오염과 제품 품질 저하(quality claim) 및 소석회 사용량에 따른 연간 원료비(연간 3억원) 등의 상당한 문제점을 나타내고 있는 실정이다. 아울러 최근 고품위 수산화알루미늄의 공급 요구에 따라 여과시 정제기준이 점차 낮아져 이제는 1mg/$\ell$ 이하를 유지하여야 하는 근본적인 문제에 봉착해있는 실정이다. 그러므로 본 연구에서는 소석회를 사용하는 입상여과법을 대체하기 위한 신공정개발을 추진하였으며, 그동안 카트리지여과법 등의 다양한 실험 결과로부터 최근 필터 보조제를 첨가하지 않는 물리적 여과방법인 세라믹 막 여과법의 적용 가능성을 확인하고 친환경공정인 세라믹 막 여과 실용화 공정 기술을 개발하였다. 세라믹 막 여과 법은 여과 보조제를 사용하지 않으므로 2차적인 슬러지 발생등의 환경문제를 발생하지 않으며, 공정액에 첨가제를 투입하지 않으므로 순환형 친환경공정으로 각광받을 수 있다. 본 연구에서는 고온, 고농도의 NaOH 수용액의 처리에 적합한 막소재와 발생될 수 있는 제반 문제점 등을 파악하였고, 장기간의 실험을 거쳐 최적 투과 압력(Trans membrane pressue), 세정 조건 및 주기, 막재질에 있어서 보강하여야 할 Point, 최적 운전 조건들을 토출해 내었고, 향후 실제 Plant에 적용할 계획이다.

• Korean Journal of Construction Engineering and Management
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• v.4 no.2 s.14
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• pp.74-81
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• 2003

In the construction industry, projects are becoming increasingly large and complex, involving multiple subcontractors. Traditional centralized coordination techniques used by the general contractors become less effective as subcontractors perform most wok and provide their own resources. When subcontractors cannot provide enough resources, they hinder their own performance as well as that of other subconractors and ultimately the entire project Thus, construction projects need a new distributed coordination approach wherein all of the concerned subcontractors can reschedule a project dynamically. To enable the distributed coordination framework of project schedule changes, the author developed an agent-based compensatory negotiation methodology, which allows intelligent software agents to simulate negotiations on behalf of their human subcontractors. In addition to this theoretical work, 1 designed and implemented a prototype to demonstrate the effectiveness of the framework. Thus, this research formalizes the necessary steps that would help construction project participants to increase the efficiency of their resource use, which in turn will enhance successful completions of whole projects.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.10
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• pp.75-84
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• 1997

This paper describes the development of an integrating method for process planning and scheduling activities for block assembly in shipbuilding. A block is composed of several steel plates and steel sections with the predetermined shapes according to the ship design. The parts which constitute the block are manufac- tured by cutting and/or bending operations, which are termed as machining operation in this paper. The machining operation is the first process for block assembly which influences the remaining block assembly processes. Thus process planning and scheduling for machining operation to manufacture parts for block are very important to meet the assembly schedule in the shipyard. An integrating method for process plan- ning and scheduling is developed by introducing the concept of distributed process planning and scheduling composed of initial planning, alternative planning and final planning stages. In initial planning stage, nesting parts information and machining emthods are generated for each steel plate. In alternative plan- ning stage, machine groups are selected and workcenter dispatching information is generated. In final planning stage, cutting sequences are determined. The integrated system is tested by case study. The result shows that the integrated system is more efficient than existing manual planning system.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.177-178
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• 2007

플라즈마 공정은 집적회로 제작을 위한 미세 박막의 증착과 패턴닝에 핵심적으로 이용되고 있다. 본 연구에서는 플라즈마공정감시와 제어에 응용될 수 있는 모델을 제안한다. 본 모델은 광방사분광기 (Optical emission spectroscopy-OES)정보와 역전파 신경망을 이용해서 개발하였다. 제안된 기법은 Oxide 식각공정에서 수집한 데이터에 적용하였으며, 체계적인 모델링을 위해 공정데이터는 통계적 실험계획법을 적용하여 수집되었다. Raw OES 정보대신, Actinometric OES 정보를 이용하였으며, 신경망의 예측성능은 유전자 알고리즘을 이용해서 증진시켰다. OES의 차수를 줄이기 위해 주인자 분석 (Principal Component Analysis-PCA)을 세 종류의 분산(100, 99, 98%)에 대해서 적용하였다. 최적화한 모델의 예측에러는 323 $\AA/min$이었다. 이전에 PCA를 적용하고 은닉층 뉴런의 함수로 최적화한 모델의 예측에러는 570 $\AA/min$이었으며, 개발된 모델은 이에 비해 43% 증진된 예측 성능을 보이고 있다.

• The Korean Journal of Applied Statistics
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• v.21 no.2
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• pp.247-264
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• 2008

This paper considers the integrated process control procedure for detecting special causes in an ARIMA(0,1,1) process that is being adjusted automatically after each observation using a minimum mean squared error adjustment policy. It is assumed that a special cause can change the process mean and the process variance. We derive expressions for the process deviation from target for a variety of different process parameter changes, and introduce a control chart, based on the generalized likelihood ratio, for detecting special causes. We also propose the integrated process control scheme bases on the future loss. The future loss denotes the cost that will be incurred in a process remaining interval from a true out-of-control signal.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.403-404
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• 2007

소자 수율을 향상시키기 위해서는 웨이퍼 전체에 걸쳐 플라즈마 공정특성이 균일하게 분포되어야 한다. 본 연구에서는 Actinomeric 광 반사분광기 (Otical Emission Spectroscopy) 정보를 이용하여 식각률 비균일도에 대한 모델을 개발하였다. 제안된 기법은 Oxide 식각공정에서 수집한 데이터에 적용하였으며, 체계적인 모델링을 위해 공정데이터는 통계적 실험계획 법을 적용하여 수집되었다. 신경망의 예측성능은 유전자 알고리즘을 이용해서 증진시켰다. OES의 차수를 줄이기 위해 주인자 분석을 세 종류의 분산(100, 99, 98%)에 대해서 적용하였다. 개발된 모델은 발표된 이전의 모델에 비해 17% 증진된 예측성능을 보였다.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.89-94
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• 2009

In this work, the optimal process has been designed by $L_9(3^4)$ orthogonal array and analysis of variance(ANOVA) for thermal-sprayed Ni-based hard coating. Ni-based hard coatings were fabricated by flame spray process on steel substrate. Then, the hardness test and observation of microstructure of the coatings were performed. The results of hardness test were analyzed by ANOVA. The ANOVA results demonstrated that the acetylene gas flow had the greatest effect on hardness of the coatings. The oxygen gas flow was found to have a neglecting effect. From these results, the optimal combination of the flame spray parameters could be predicted. The calculated hardness of the coatings by ANOVA was found to lie close to that of confirmation experimental result. Thus, it was considered that design of experiments design using orthogonal array and ANOVA was useful to determine optimal process of thermal-sprayed Ni-based hard coating.

• Journal of Korea Port Economic Association
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• v.27 no.1
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• pp.75-94
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• 2011

This paper is concerned about applying the AHP(Analytic Hierarchy Process) for a priority analysis of equipment operation plan to improve productivity of the container terminal in Gwangyang port. In this study, main elements of container terminal are assumed as into yard equipment area, transport equipment area, berth equipment area and C/Center area. A questionnaire is used to collect the opinions of equipment operating department and operational planning department. On the whole, the result of the analyses reveals that the most important area is yard equipment area. Examining each department is responses, equipment operating department preferred the C/Center area to other areas, on the other hand, operational planning department preferred yard equipment area. The result of this study suggests some guidelines for deciding priority of operation plan in the container terminal.