• Journal of the Korean Data and Information Science Society
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• 제27권2호
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• pp.539-548
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• 2016

This paper is a study on the multivariate CUSUM control charts using three different control statistics for monitoring covariance matrix. We get control limits and ARLs of the proposed multivariate CUSUM control charts using three different control statistics by using computer simulations. The performances of these proposed multivariate CUSUM control charts have been investigated by comparing ARLs. The purpose of control charts is to detect assignable causes of variation so that these causes can be found and eliminated from process, variability will be reduced and the process will be improved. We show that the charts based on three different control statistics are very effective in detecting shifts, especially shifts in covariances when the variables are highly correlated. When variables are highly correlated, our overall recommendation is to use the multivariate CUSUM control charts using trace for detecting changes in covariance matrix.

• 한국생산제조학회지
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• 제9권2호
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• pp.72-79
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• 2000

A new optimal tool design model which can be minimized the resultant cutting forces under the constrains of variables was developed. The resultant cutting forces are used as the objective function and tool angles are used as the variables. Cutting experiments of tool wear and chip length using the new and conventional tools wee carried out. Tool life of optimized cutter are more increased than those of conventional cutter by 2.29 times and 2.52 times at light and at heavy cutting conditions respectively. Chip length of optimized cutter are more increased than those of conventional cutter It is considered that the decrease of the resultant cutting forces is the cause that an effective rake and shear angles by the shape of optimal cutter.

• International Journal of Automotive Technology
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• 제7권7호
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• pp.859-866
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• 2006

This study employed the perturbation method, the Edgeworth series, the reliability optimization, the reliability sensitivity technique and the robust design to present a practical and effective approach for the robust reliability design of vehicle components with arbitrary distribution parameters on the condition of known first four moments of original random variables. The theoretical formulae of the robust reliability design for vehicle components with arbitrary distribution parameters are obtained. The reliability sensitivity is added to the reliability optimization design model and the robust reliability design is described as a multi-objection optimization. On the condition of known first four moments of original random variables, the respective program can be used to obtain the robust reliability design parameters of vehicle components with arbitrary distribution parameters accurately and quickly.

• 소성∙가공
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• 제9권3호
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• pp.257-264
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• 2000

In this study, optimization for press forming condition of low arm was performed with explicit dynamic FEM code, Pam-Stamp. FEM simulation was coupled with the Taguchi's experiment technique having three design variables - friction coefficient, plastic anisotropy parameter, and blank shape - which are chosen to be optimized. The simulation results were compared with those of experiment. We found out the change of blank shape among these three design variables is very effective in optimizing press forming condition of low arm. In addition, the modified blank shape shows high yield of slitting coil.

• 산업공학
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• 제15권4호
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• pp.426-431
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• 2002

In many cases, the result of a road traffic accident can be described with more than one response variables. Nonetheless, most of the existing road accident data analysis deal with only one response variable and try to explain why it occurs. In this paper, we train association rules for a set of more than two response variables conditional on personal, environmental and vehicular/behavioral aspects of accident. Association rules are derived at 8% support and 70% confidence from the 1996 data of three police stations in Korea. We expect that these rules can contribute to effective safety practice in Korea.

• 품질경영학회지
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• 제40권1호
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• pp.25-38
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• 2012

Service FMEA may yield several possible corrective actions for each failure mode with large RPN. Corrective actions for each service failure are usually interrelated with the customers and environmental elements of the service system. SWOT analysis can provide an effective way to analyze the inner and outer environmental impacts for each corrective action. In this paper, we suggest a way for selecting and ranking corrective strategy in service operation based on SWOT analysis. Every candidate of corrective action strategy is ranked and evaluated on the basis of the impact factors of the SWOT variables, correlations between possible corrective actions and SWOT variables, and RPNs of service failures. The most desirable set of corrective actions is selected considering the preference score of each corrective action, required resources and budgetary allowance. The proposed methodology is demonstrated with an illustrative example.

• 한국학교보건학회지
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• 제15권2호
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• pp.167-182
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• 2002

The purpose of this study was to examine the factors related to adolescence' post-sexual assault attitudes and behaviors. 906 students from 5girls high schools completed self-reported questionnaires. Independent variables are sexual attitudes, rape myth acceptance, perceived importance of sexuality education, parent sexuality education, parent closeness, parent superintendence, family functioning and socioeconomic variables. The data were analyzed by Factor Analysis, Correlation Analysis, Stepwise Multiple Regression Analysis using SPSS program. The significant influencing factors were home sexuality education, perceived necessity & importance of sexuality education, parent closeness, parent superintendence, family functioning, grade, vocational school, rape myth(rapists are mentally ill, dating partner would not be rapist. rapists are stranger), sexual attitudes(sexual permissiveness, gender equality, family planning, STDs & prostitution, marriage and divorce and abortion), and dating experience. Examination of barriers to post-sexual assault coping behaviors and attitudes is critical component of victim recovery and rape prevention. This study would gives basic information to the effective prevention and coping program development related to sexual assault.

• Management Science and Financial Engineering
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• 제10권1호
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• pp.97-106
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• 2004

In this paper, we propose an effective cut generation method based on the Chvatal-Gomory procedure for a variable-capacity (0,l)-Knapsack problem with two general integer variables. We first derive a class of valid inequalities for the problem using Chvatal-Gomory procedure, then analyze the associated separation problem. Based on the results, we show that there exists a pseudo-polynomial time algorithm to solve the separation problem. By analyzing the theoretical strength of the inequalities which can be generated by the proposed cut generation method, we show that generated inequalties define facets under mild conditions. We also extend the result to the case in which a nontrivial upper bound is imposed on a general integer variable.

• 대한물리치료과학회지
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• 제16권3호
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• pp.1-9
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• 2009

Background: The purpose of this study is to have examined the influence on the blood circulation by comparing the differences between stimulating the sympathetic ganglion and the muscle group among the stimulation variables in interferential current stimulation. Method: The object of the study is the twenties(M=8, F=12), who are in great condition and have no pathological report for the blood circulation influence. The intensity of the inferential current stimulation is the medium degree, 100 bps constant current, which is the comfort and degree to confirm the muscle contraction. The areas stimulated are the stellate ganglion area in the seventh cervical vertebrae and the forearm muscle area. Results: We have made sure that there is no change in blood pressure and pulse and that the change in the skin temperature occurred highly. Conclusion: In considering the change of the blood circulation in case of stimulation area by the inferential current stimulation, we have seen that stimulating the sympathetic ganglion area is more effective than stimulating muscle area directly.

• Structural Engineering and Mechanics
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• 제36권1호
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• pp.19-36
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• 2010

The load and resistance factors are generally obtained using the First Order Reliability Method (FORM), in which the design point should be determined and derivative-based iterations have to be used. In this paper, a simple method for estimating the load and resistance factors using the first four moments of the basic random variables is proposed and a simple formula for the target mean resistance is also proposed to avoid iteration computation. Unlike the currently used method, the load and resistance factors can be determined using the proposed method even when the probability density functions (PDFs) of the basic random variables are not available. Moreover, the proposed method does not need either the iterative computation of derivatives or any design points. Thus, the present method provides a more convenient and effective way to estimate the load and resistance factors in practical engineering. Numerical examples are presented to demonstrate the advantages of the proposed fourth moment method for determining the load and resistance factors.