• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.2
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• pp.18-27
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• 2019

The process control methods based on the statistical analysis apply the analysis method or mathematical model under the assumption that the process characteristic is normally distributed. However, the distribution of data collected by the automatic measurement system in real time is often not followed by normal distribution. As the statistical analysis tools, the process capability index (PCI) has been used a lot as a measure of process capability analysis in the production site. However, PCI has been usually used without checking the normality test for the process data. Even though the normality assumption is violated, if the analysis method under the assumption of the normal distribution is performed, this will be an incorrect result and take a wrong action. When the normality assumption is violated, we can transform the non-normal data into the normal data by using an appropriate normal transformation method. There are various methods of the normal transformation. In this paper, we consider the Box-Cox transformation among them. Hence, the purpose of the study is to expand the analysis method for the multivariate process capability index using Box-Cox transformation. This study proposes the multivariate process capability index to be able to use according to both methodologies whether data is normally distributed or not. Through the computational examples, we compare and discuss the multivariate process capability index between before and after Box-Cox transformation when the process data is not normally distributed.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.157-163
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• 2000

Testing evaluation is a part of process for design, production, evaluation, operation and abolition, and is the process of certifying system performance. The main purpose of testing evaluation is to reduce the risk factor under the determining process. Testing process has the three step such as design qualification, integration and validation test in factory, system integration and commissioning test. Design Qualification is to verify errors on the design process. Integration and validation test in factory is for the H/W and S/W of an equipment and is to verify interface of subsystem, communication protocol and main functions. System integration and commissioning test is a functional test to adjust successful installation of equipment. According to the testing process, briefly consideration for test item, test method and test contents about signalling system is carried out.

• Journal of the Korean Statistical Society
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• v.30 no.3
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• pp.481-498
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• 2001

Empirical Bayes procedure of nonparametric estiamtion of cumulative hazard rates based on censored data is considered using the beta process priors of Hjort(1990). Beta process priors with unknown parameters are used for cumulative hazard rates. Empirical Bayes estimators are suggested and asymptotic optimality is proved. Our result generalizes that of Susarla and Van Ryzin(1978) in the sensor that (i) the cumulative hazard rate induced by a Dirichlet process is a beta process, (ii) our empirical Bayes estimator does not depend on the censoring distribution while that of Susarla and Van Ryzin(1978) does, (iii) a class of estimators of the hyperprameters is suggested in the prior distribution which is assumed known in advance in Susarla and Van Ryzin(1978). This extension makes the proposed empirical Bayes procedure more applicable to real dta sets.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.497-503
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• 2008

The Oxic-Settling-Anaerobic(OSA) process is a modified activated sludge processes for sludge reduction. It is evaluated that the sludge production in OSA process can decrease to 88% because of biomass decay and kinetic parameter($Y_H$ 0.237mgVSS/mgCOD, $b_H$ $0.195d^{-1}$) in anaerobic reactor, when compared with CAS process. However, it has problems caused by sludge reduction such as increase of nutrient loading. In case that the anoxic condition through the introduction of the intermittent aeration for the enhancement of nitrogen removal ability build up and enough rbCOD is suppled, maximum 88% of nitrogen is removed in the OSA process. If the OSA process optimizing the intermittent aeration cycle is applied to the separate sewage system with high rbCOD fraction, it can be converted to advanced process in terms of the sludge reduction and nitrogen removal, simultaneously.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.491-495
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• 2002

In the paper, a Visual factory model for a optical-components manufacturing process is built. The optical-components manufacturing process is composed of 3 operation processes; optical sub assembly process, package assembly process, and fiber assembly process. Each process is managed not a batch mode, which is one of most popular manufacturing styles to produce a great deal of industrial output, but though a modular cell. In the processes, a modular cell has to be processed independently of the other cells. Optimization for the composition of assembly cell in the optical-components system is made by the Visual factory model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2262-2269
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• 2002

Process optimization is carried out to determine process parameters which satisfy the given design requirement and constraint conditions in sheet metal forming processes. Sensitivity -based-approach is utilized for the optimum searching of process parameters in sheet metal forming precesses. The scheme incorporates an elasto-plastic finite element method with shell elements . Sensitivities of state variables are calculated from the direct differentiation of the governing equation for the finite element analysis. The algorithm developed is applied to design of the variablc blank holding force in deep drawing processes. Results show that determination of process parameters is well performed to control the major strain for preventing fracture by tearing or to decrease the amount of springback for improving the shape accuracy. Results demonstrate that design of process parameters with the present approach is applicable to real sheet metal forming processes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.636-639
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• 2002

In the paper, a Visual factory model for a optical-components manufacturing process is built. The optical-components manufacturing process is composed of 3 operation processes; optical sub assembly process, package assembly process, and fiber assembly process. Each process is managed not a batch mode, which is one of most popular manufacturing styles to produce a great deal of industrial output, but though a modular cell. In the processes, a modular cell has to be processed independently of the other cells. Optimization for the composition of assembly cell in the optical-components system is made by the Visual factory model.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.258-261
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• 2003

In this study, finite element analysis for multi-stage deep drawing process of rectangular configuration with extreme aspect ratio is carried out especially for the blank design. The analysis of rectangular deep drawing process with extreme aspect ratio is likewise very difficult with respect to the design process parameters including the intermediate die profile. In order to solve the difficulties, numerical approach using finite element method is performed in the present analysis and design. A series of experiments for multi-stage rectangular deep drawing process are conducted and the deformed configuration is investigated by comparing with the results of the finite element analysis. Additionally, to minimize amount of removal material after trimming process, finite element simulation is applied for the blank modification. The analysis incorporates brick elements for a rigid-plastic finite element method with an explicit time integration scheme using LS-DYNA3D.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.174-181
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• 1999

In this paper the technique to predict tool wear theoretically in shearing process is suggested. The tool wear in the process affects the tolerances of final pans, metal flows and costs of processes. In order to predict the tool wear the deformation of workpiece during the process is analyzed by using non-isothermal finite element program. The ductile fracture criterion and the element kill method are also used to estimate if and where a fracture will occur and to investigate the features of the sheared surface in shearing process. Results obtained from finite element simulation, such as nodal velocities and nodal forces, are transformed into sliding velocity and normal pressure on tool monitoring points respectively. The monitoring points are automatically generated and the wear rates on these points are accumulated during the process. It is assumed that the wear depth on the tool surface is linear function of the lot sizes based upon the known experimental results. The influence of clearance between die and punch upon tool wear is also discussed.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.492-498
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• 2001

In the previous study, temperature monitoring of case about shrinkage fit process was performed and heat transfer model was developed in detail by feedback and tuning among monitoring result, process investigation, and analysis result. The gap element in contact between case and core was effectively used in analysis model. In present study, following things are performed to solve deformation of case due to shrinkage fit process on the basis of previous result. Above all, mechanical material properties of case are measured by case specimen for deformation analysis considering weldment of case. Deformation of case before and after shrinkage fit process is measured, too. Three dimensional deformation model is developed by the comparison and inspection between these experimental data and analysis results. Deformation analysis is simulated with the result of heat transfer analysis, in other words, non-coupled analysis is used. Finally the countermeasure for deformation is brought up through those.