• 품질경영학회지
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• 제33권3호
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• pp.135-148
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• 2005

This paper considers a six sigma project for reducing the project costs through project risk management. The project follows a disciplined process of five phases: define, measure, analyze, improve, and control. A risk management process map is used to identify process input and output variables. Seven key process input variables are selected by using C&E diagram and X-Y matrix and finally four vital few input variables are selected by the related statistical analysis. The optimum alternatives of the vital few input variables are obtained by the method of PUGH matrix. The process is running on control plan and we obtained substantial project cost reductions in early stage of the control phase.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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• pp.205-209
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• 1997

One of the major important tasks in the robotic $CO_2$ arc welding process is to understand how process variables affected bead geometry and to subsequently develop the mathematical models to predict the desired bead dimensions. Experiment results are compared to outputs obtained using a set of published formulae relating input variables to output parameters and also investigated process variables on bead geometry for robotic $CO_2$ arc welding process The university of results obtained using empirical equations taken from existing models provided to be limited in predicting experimental bead shapes.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2004년도 품질경영모델을 통한 가치 창출
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• pp.513-516
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• 2004

Evolutionary operation is useful to improve on-line full-scale manufacturing processes by systematically changing the levels of the process variables while meeting production schedule. Evolutionary operation was developed using two or three process variables for process operators who are not good at statistics. Recently, when a product is developed, it is very important for the engineers to make the production line stable as soon as possible. And there are many causes which have influences to the product performance. This paper presents an evolutionary operation procedure with many process variables using saturated two level fractional factorial designs including Plackett-Burman design.

• 소성∙가공
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• 제11권7호
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• pp.581-588
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• 2002

Among the processes to produce micro lens, the process using press molding is a new technology to simplify the process, but it contains many unknown variables. The press-molding process proposed in this paper was simplified into two step process, the first step is the pressing to design the preform for glass element, the second step is the annealing to reduce the residual stress. It is important to estimate the amount of shrinkage of glass gob and the residual stress during process. It Is difficult to evaluate the process variables as mentioned above through the experiment. The influences due to process variables was evaluated by using FEM parametric analysis. The results in this paper can be applicable to produce micro lens.

• 산업경영시스템학회지
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• 제39권1호
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• pp.123-129
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• 2016

In the manufacturing industry fields, thousands of quality characteristics are measured in a day because the systems of process have been automated through the development of computer and improvement of techniques. Also, the process has been monitored in database in real time. Particularly, the data in the design step of the process have contributed to the product that customers have required through getting useful information from the data and reflecting them to the design of product. In this study, first, characteristics and variables affecting to them in the data of the design step of the process were analyzed by decision tree to find out the relation between explanatory and target variables. Second, the tolerance of continuous variables influencing on the target variable primarily was shown by the application of algorithm of decision tree, C4.5. Finally, the target variable, loss, was calculated by a loss function of Taguchi and analyzed. In this paper, the general method that the value of continuous explanatory variables has been used intactly not to be transformed to the discrete value and new method that the value of continuous explanatory variables was divided into 3 categories were compared. As a result, first, the tolerance obtained from the new method was more effective in decreasing the target variable, loss, than general method. In addition, the tolerance levels for the continuous explanatory variables to be chosen of the major variables were calculated. In further research, a systematic method using decision tree of data mining needs to be developed in order to categorize continuous variables under various scenarios of loss function.

• 과학교육연구지
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• 제33권2호
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• pp.271-289
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• 2009

이 연구는 생물학자와 과학영재의 실험설계활동에서 나타나는 과정요소와 특성을 분석한 것이다. 연구대상으로 동물행동생태를 전공한 생물학자 4명과 과학영재 생물반 학생 32명을 선정하였고, 연구를 위해 주어진 과제는 Fowler(1990)의 DCT이다. 그들의 실험설계활동과 관련된 모든 자료를 수집하였고, 이 자료를 분석하기 위한 분석틀을 개발하였다. 분석 결과, 첫째, 생물학자와 과학영재의 실험설계활동에서 나타난 과정요소는 문제 확인, 준비물 열거, 실험대상에 대한 고려, 변인 탐색, 변인 소거, 변인 선택, 변인 조작 방법 계획, 환경적 변인 통제 계획, 생물적 변인 통제 계획, 관찰 측정 방법 계획, 자료 수집 계획, 자료 해석 계획, 실험의 반복 계획, 측정의 반복 계획, 안전 수칙으로 총 15가지가 있다. 생물학자는 특정한 과정요소에 집중하는 반면, 과학영재는 정형화된 과정요소를 나타냈다. 둘째, 생물학자와 과학영재의 실험설계활동에서 나타난 특성을 종합하면 다음과 같다: 1) 생물학자와 과학영재 모두 영역특수적인 과정기술이 포함된 과정요소를 나타냈다. 2) 생물학자는 특정한 과정을 반복적으로 점검하면서 정교하게 실험을 설계하는 반면, 과학영재는 피상적으로 실험을 설계한다. 3) 생물학자는 영역특수적인 기술과 노하우를 가지고 있으나, 과학영재는 그렇지 않다. 이러한 결과는 과학영재의 실험설계활동 교육 프로그램은 생물학자들이 집중하는 과정요소를 중심으로 구성하고, 정교한 실험 설계를 할 수 있도록 피드백을 제공하고, 생물학자의 과정기술이나 노하우를 학습할 수 있는 형태로 개발되어야 함을 시사한다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.76-80
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• 2003

The procedure of finding operating conditions minimizing qualify loss is proposed with a real industry example. The procedure consists or major two parts - the selection or process variables critical to the response and He determination or operating conditions. The coefficients or ridge regression and the and stores or partial least squares are applied to select important process variables. Functional approach and Non-functional approach are used to find proper operating conditions of important process variables.

• 소성∙가공
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• 제19권2호
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• pp.132-137
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• 2010

In the multi-pass shape drawing process, the appropriate process design is very important to produce sound products. The reduction ratio, die angle, and the intermediate die shape are very important process variable of the multi-pass shape drawing. The aim of this study is the determination of the reduction ratio, die angle, and the intermediate die shape of the 2 pass shape drawing process for producing steering spline shaft. In this study, FE analysis, Taguchi method, and ANN(artificial neural network) were applied to determine the appropriate reduction ratio, die angle, and intermediate die shape. After the determination of the process variables, FE analysis and drawing experiment were performed to evaluate the effectiveness of the determined process variables. The dimensional accuracy of the final drawn spline shaft was evaluated by using 3D surface profiler and 3D laser digitizing system.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 춘계학술대회 논문집
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• pp.36-41
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• 1997

With the trend towards welding automation and robozation, mathematical models for studying the influence of various parameters on the weld bead geometry in Gas Metal Arc(GMA) welding process are required. The results of bead on plate welds deposited using the GMA welding process has enabled mathematical relationships to be developed that model the weld bead geometry. Experimental results were compared to outputs obtained using existing formulae that correlate process input variables to output parameters and subsequent modelling was performed in order to better predict the output of the GMA welding process. The aim of this work was to explain the relationships between GMA welding variables and weld bead geometry and thus, be able to predict input weld bead size. The relationships can be usefully employed for open loop process control and also for adaptive control provided that dynamic sensing of process output is performed.

• 한국초전도ㆍ저온공학회논문지
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• 제8권1호
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• pp.23-25
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• 2006

Optimization of process variables, including oxygen and water partial pressure and also an nesting temperature, was performed in batch-type process to fabricate YBCO films on LaAlO3 single crystal. In this work, YBCO oxide powder was used as a starting precursor for metal-organic deposition(MOD)method. The precursor films were fabricated in batch furnace and they were converted to the epitaxial YBCO films at the same furnace with varying the process variables. The oxygen partial pressure was varied from 100ppm to 2000ppm and the water partial pressure from 1.2% to 12.2%. The window for optimal P(O2) was narrow about 700ppm for batch-type process. YBCO films in bathc-thype MOD process were optimized at 740-770oC and P(H2O) of 2.3%-7.3%.