• 한국정밀공학회지
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• 제13권4호
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• pp.163-173
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• 1996

Stereolithography is a process used to rapidly produce polymer components directly form a computer representation of the part. There are several considerations to be made for the efficient use of the process. Especially, the build-up orientation of part critically affects the part accuracy, total build time and the volume of support structures. The purpose of tis study is to determine the optimal build-up part orientation for the SLA process with improving part accuracy, and minimizing total build time and the volume of support structures. The forst factor is related to the area of surfaces whioch have staircase protrusions after solidification, the second factor is related to the total number of layers, and the third factor is related to the area of the surfaces which need to be supported with support structures. An algorithm is developed to calculate the staircase area, quantifying the process errors by the volume of materials supposed to be removed or added to the part, and the optimal layer thickness for the SLA system which can handle the variable layer thickness. So the optima l part orientation is determined based on the user's selections of primary criter- ion and the optimal thickness of layers is calculated at any part orientations.

• 품질경영학회지
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• 제47권1호
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• pp.87-96
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• 2019

Purpose: The purpose of this paper is to determine an optimal production time for economic production quantity model with preventive maintenance and random defective rate as the function of a machinery deteriorates. Methods: If a machinery shifts from "in-control" state to "out-of-control" state, a proportion of defective items being produced increases. It is assumed that time to state shift is a random variable and follows an arbitrary distribution. The elapsed time until process shift decreases stochastically as a production cycle repeats and quasi-renewal process is used to implement for production facilities to deteriorate. Results: When the exponential parameter for exponential distribution increases, the optimal production time increases. When Weibull distribution is considered, the optimal production time is closely affected by the shape parameter of Weibull distribution. Conclusion: A mathematical model is suggested to find optimal production time and optimal number of production cycles and numerical examples are implemented to validate the patterns for changes of optimal times under different parameters assumptions. The real application is implemented using the proposed approach.

• 공업화학
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• 제16권2호
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• pp.217-225
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• 2005

H사의 유로변경식 고도하수처리 공법의 제어 변수가 DO와 수온 등으로 한정되어 있어 효율성의 만족도를 충족시켜주지 못하는 현재의 상황을 개선하고자 세 가지 개선방향을 설정하여 Simulation을 통한 Operation Data의 분석 및 장치구성과 실험을 통한 최적제어 Logic을 연구하여 이를 다시 S하수처리장에 설치 적용한 결과이다. 본 실험을 통해서 수온과 유량에 근간한 Operation Mode 변경의 최적화와 이를 통한 동력비 절감을 이루었고 암모니아성 질소의 농도에 따른 Operation Mode의 변경에서 일반 Normal Mode와 병행하여 Save Mode를 새로 적용하여 동력비 절감을 이루었다. 또한 DO 값을 송풍량과 수중폭기기의 교반속도에 의해 비례제어하고 유출수의 암모니아 농도에 따라 DO 값을 제어하여 안정적인 질산화를 이루었다. 이러한 결과는 공정효율의 극대화와 운영 및 유지관리비의 절감을 이루었다.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2010년도 추계학술대회
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• pp.199-207
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• 2010

Decision analysis has becomes an important technique for decision making in the face of uncertainty. It is characterized by enumerating all the available courses of action, identifying the payoffs for all possible outcomes, and quantifying the subjective probabilities for the all possible random events. When the data are available, decision analysis becomes a powerful tool for determining an optimal course of action. In this paper, we use the analytic hierarchy process in weights calculating. For the purpose of making optimal decision, the data of three different smart phones models are used.

• 대한산업공학회지
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• 제20권1호
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• pp.3-13
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• 1994

The problem of selecting the optimal target values in a canning process is considered for situations where there is a linear shift in the mean of the content of a can which is assumed to be normally distributed with known variance. The target values are initial process mean, length of resetting cycle and controllable upper limit. Profit models are constructed which involve give-away, rework, and resetting costs. Methods of finding the optimal target values are presented and a nemerical example is given.

• 산업경영시스템학회지
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• 제10권15호
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• pp.33-38
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• 1987

In establishing Multi-Stage Machining process inspection procedures, however, where costs of inspection md defective products are often directly measurable, a better method for formulating inspection plans is available. If one of the primary interest of a manufacturing concern is to maximize profits, then optimal inspection plans ought to be selected so as to minimize costs. This paper is aimed to find a methodology of optimal inspection planning in Multi-stage Machining process and to develope a proper algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.560-565
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• 1986

For the control of chemical process, optimal value of the process should be known at first. And process simulation is the previous step of optimal value calculation. However it is not a simple work to analyze chemical process system. Especially for the large scale chemical process system, many difficulties such as non-linearity and complexity caused by recycle streams should be overcome. In this paper, three strategies of large scale chemical process analysis were explained and discussed with case studies.

• 소성∙가공
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• 제20권4호
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• pp.291-295
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• 2011

The injector housing has two functions, namely, positioning the injector and protecting it from coolant. The conventional manufacturing process of the injector housing by machining has some drawbacks such as considerable loss of material and environmental pollution caused by excessive use of cutting oil. In this paper, precision cold forging is proposed as a new manufacturing process in order to improve these issues. A numerical study was conducted to compute the metal flow, strain, load and other process variables using DEFORM-2D, a finite element analysis(FEA) code for metal forming. Two process methods were investigated and optimal conditions were computed with the FEA code. A prototype was manufactured from the optimal process method and the metal flow and hardness were obtained from the prototype.

• 한국생산제조학회지
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• 제18권6호
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• pp.590-597
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• 2009

The final quality of the workpiece is affected by the grinding process that has been conducted in final manufacturing stage. However the quality-satisfaction of ground workpiece depends on the skill of an expert in this process. Therefore, the process models of grinding have been developed to predict the states according to grinding process. In this paper, in order to find the optimized grinding condition to reduce the manufacturing expense and to meet requirements of ground workpiece optimization algorithm using E.S.(Evolutionary Strategy) is proposed. The proposed algorithm has been employed to find the optimal grinding and dressing condition using the grinding process models and nonlinear grinding constraints. The optimized results also presents the guide line of grinding process. The effectiveness of the proposed algorithm is verified through the experimental results.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1209-1214
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• 2006

This paper presents an application of Dividing Wall Column(DWC) to the recovery of the waste solvent from the film making processes. The waste solvent feed contains MEK(Methyl-Ethyl-Ketone), Toluene, Cyclohexanone, and water. The commercial software $HYSYS^{TM}$ was used for rigorous simulation and analysis. Sensitivity analysis for several major design variables were carried out to achieve the optimal design of the process. Distribution of the internal vapor and liquid flows to the prefractionator and main sections is shown to be the most dominant design factor for energy saving efficiency in the DWC process. The simulation results also show that the solvent recovery process using the DWC significantly improves both the energy efficiency and the compactness of the solvent recovery process.