• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.3
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• pp.183-188
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• 2005

Although it is widely used to find an optimum setting of manufacturing process parameters in a variety of engineering fields, the Taguchi method has a difficulty in dealing with multi-response situations in which several response variables should be considered at the same time. For example, electrode wear, surface roughness, and material removal rate are important process response variables in an electrical discharge machining (EDM) process. A simultaneous optimization should be accomplished. Many researches from various disciplines have been conducted for such multi-response optimizations. One of them is a fuzzy logic approach presented by Lin et al. [1]. They showed that two response characteristics are converted into a single performance index based upon fuzzy logic. However, it is pointed out that information regarding relative importance of response variables is not considered in that method. In order to overcome this problem, a desirability function can be adopted, which frequently appears in the statistical literature. In this paper, we propose a novel approach for the multi-response optimization by incorporating fuzzy logic into desirability function. The present method is illustrated by an EDM data of Lin and Lin [2].

• Asia pacific journal of information systems
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• v.9 no.4
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• pp.181-201
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• 1999

This study presents an information security level index and a quantification scheme. A comprehensive survey on previous researches in information security checklists has been performed. A candidate indicator list for information security level has been developed, Desirability of each indicator has been tested by 4 criteria, They are general validity, relative importance, probability of accident and impact of accident. 67 experts' opinion has been collected and analysed. The result shows that selected indicators are a very good candidate set for the determination of information security level. A factor analysis shows indicators are well structured. There exists strong correlation between validity and probability, validity and impact, and importance and probability. A quantification scheme of information security index has been developed by experts' judgement and statistical tests.

• The Korean Journal of Applied Statistics
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• v.15 no.1
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• pp.165-177
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• 2002

This poper proposes a manpower cultivation index(MCI) which can be used for evaluating how much a research project contributes for manpower cultivation. The four factors which are considered to influence the manpower cultivation are the number of participated graduate students(research assistants) , the number of graduate students who obtain master or Ph. D. degrees among the participated graduate students in the research project, the number of research papers published by participated graduate students, and the number of graduate students who get jobs. By the proposed MCI, three major research projects of KOSEF are analysed in terms of manpower cultivation. These are SRC/ERC(Science research center/Engineering research center) and RRC(Regional research center) and OBR(Objective based research) . The computed MCls show that the three major research projects enjoy satisfactory manpower cultivation to some extent.

• Communications for Statistical Applications and Methods
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• v.10 no.2
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• pp.399-422
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• 2003

In actual manufacturing industries, process capability analysis often entails characterizing or assessing processes or products based on more than one engineering specification or quality characteristic. Since these characteristics are related, it is a risky undertaking to represent variation of even a univariate characteristic by a single index. Therefore, the desirability of using vector-valued process capability index(PCI) arises quite naturally. In this paper, some vector-valued ${PCI}_p$ ${C}_p$=(${C}_{px}$, ${C}_{py}$),${C}_{pk}$=(${C}_{pkx}$, ${C}_{pky}$) and ${C}_{pm}$=(${C}_{pmx}$, ${C}_{pmy}$) considering univariate PCIs ${C}_p$,${C}_{pk}$ and ${C}_{pm}$ are studied. First, we propose some asymptotic confidence regions of our vector-valued PCIs with bootstrap. And we examine the performance of asymptotic confidence regions of our vector-valued PCIs ${C}_p$ and ${C}_{pk}$ under the assumption of bivariate normal distribution BN($\mu_{x}$, $\mu_{y}$, $\sigma_{x}^{2}$, $\sigma_{y}^{2}$, $\rho$) and bivariate chi-square distribution Bivariate $x^2$(5,5,$\rho$).

• Korean Journal of Computational Design and Engineering
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• v.18 no.5
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• pp.359-366
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• 2013

In the lower arm design process, a tolerance optimization of the variance of design variables should be preceded before manufacturing process, since it is very cost-effective compared to a strict management of tolerance of products. In this study, a design of experiment (DOE) based on response surface model (RSM) was carried out to find optimized design variables of the lower arm, which can meet a given requirement of probability constraint for the process capability index (Cpk) of the weight and maximum stress. Then, the design space was explored by using the central composite design method, in which the 2nd order Taylor expansion was applied to predict a standard deviation of the responses. The optimal solutions satisfying the probability constraint of the Cpk were found by considering both of the mean value and the standard deviation of the design variables.

• Communications for Statistical Applications and Methods
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• v.18 no.3
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• pp.377-389
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• 2011

A higher quality level is generally perceived by customers as improved performance by assigning a correspondingly higher satisfaction score. The third generation index $C_{pmk}$ is more powerful than two useful indices $C_p$ and $C_{pk}$ that have been widely used in six sigma industries to assess process performance. In actual manufacturing industries, process capability analysis often entails characterizing or assessing processes or products based on more than one engineering specification or quality characteristic. Since these characteristics are related, it is a risky undertaking to represent the variation of even a univariate characteristic by a single index. Therefore, the desirability of using vector-valued process capability index(PCI) arises quite naturally. In this paper, we consider more powerful vector-valued process capability index $C_{pmk}$ = ($C_{pmkx}$, $C_{pmky}$)$^t$ that consider the univariate process capability index $C_{pmk}$. First, we examine the process capability index $C_{pmk}$ and plug-in estimator $\hat{C}_{pmk}$. In addition, we derive its asymptotic distribution and variance-covariance matrix $V_{pmk}$ for the vector valued process capability index $C_{pmk}$. Under the assumption of bivariate normal distribution, we study asymptotic confidence regions of our vector-valued process capability index $C_{pmk}$ = ($C_{pmkx}$, $C_{pmky}$)$^t$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1270-1277
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• 2003

The extrusion conditions of the soymilk residue and corn grits mixtures were optimized. The experiment was designed according to the D-optimal design of response surface methodology (RSM), which shows 18 experimental points including 4 replicates for three independent variables (screw speed, water content and die temperature). The responses variables such as bending force, expansion ratio, bulk density, water solubility index (WSI), water absorption index (WAI), and color values (L＊, a＊, b＊) were evaluated using response surface analysis. Expansion ratio and WSI decreased with increasing water content, whereas bulk density tended to increase with increasing water content. While greater screw speeds enhanced WSI and yellowness, higher moisture contents decreased the expansion ratio and WSI value. However, die temperature did not influence upon the response variables. The optimum extrusion conditions by numerical and graphical methods were similar: the screw speed, water content, and die temperature were 250 rpm, 22.43% and l28.16$^{\circ}C$ by the numerical method; 250 rpm, 22.43%, and 128.02$^{\circ}C$ by graphical method.

• The korean journal of orthodontics
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• v.43 no.1
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• pp.35-41
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• 2013

Objective: To assess the prevalence of malocclusion and its relationship with dental caries among school children in southern India. Methods: This cross-sectional study included 1,800 students aged 11 - 15 years whose Dental Aesthetic Index (DAI) and dentition status were recorded and analyzed. The chi-square test, ANOVA, and Spearman's correlation tests were carried out. Results: The mean DAI score ${\pm}$ the standard deviation was $18.61{\pm}6.1$. Approximately 85% of the students (83.0% males, 86.8% females) had DAI scores of < 26 and were classified as not requiring orthodontic treatment. One tenth of the sample had mean DAI scores between 26 - 30 (indicating definite malocclusion and elective treatment), while about 3% had mean scores between 31 - 35 (indicating severe malocclusion and treatment desirability). Only 29 children (1.6%; 16 boys, 13 girls) had a DAI score of > 35, which suggested very severe or handicapping malocclusion requiring mandatory treatment. The mean decayed, missing, filled teeth (DMFT) was $2.28{\pm}1.47$. A DMFT of > 0 was observed in 91.8% of the study subjects. Children with a DAI score of > 35 were found to have significantly (p < 0.001) higher caries experience as compared to other children. Moreover, the DAI scores showed a significant correlation with the mean DMFT scores (r = 0.368, p < 0.05). Conclusions: A positive correlation was found between the severity of malocclusion and dental caries.

• Journal of Korean society of Dental Hygiene
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• v.10 no.2
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• pp.345-359
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• 2010

Objectives : The purpose of this study was to correlation between the index of dental caries in primary teeth and the habits of diet and snack which are expected to influence on the index. The subjects of this study were 165 parents of the children who visited a pediatric dental hospital located in Gyeong-gi do from Jun. 15th to Sep. 26th, 2009, and the self-report questionnaire survey was performed. Methods : A questionnaire used in a previous study was revised and completed for this study and it consisted of 15 items on general characteristic, nine items on dietary habit, and five items on snack intake habit. The collected data was analyzed using SPSS program and findings are as follows Results : 1. The index of dental caries in primary teeth by ages was that children of four years old has 4~5 with 27.5%, children of five years old has 2~3 and 4~5 with 33.3% and children of six years old has 1 and 8~9 with 25.6%, showing a statistically significant(${\chi}^2$=37.72, p<.01). 2. The frequency of brushing teeth was found to have statistically significant negative correlation with the number of primary teeth with dental caries (${\chi}^2$=61.20, p<.001). 3. The frequency of taking snack was found to have statistically significant positive correlation with the number of primary teeth with dental caries (${\chi}^2$=51.42, p<.001). 4. The desirability of dietary habit was found to have statistically significant negative correlation with the number of primary teeth with dental caries (${\chi}^2$=36.51, p<.001). 5. The frequency of taking biscuit was found to have statistically significant positive correlation with the number of primary teeth with dental caries (${\chi}^2$=67.74, p<.001). 6. The frequency of taking bread was found to have statistically significant positive correlation with the number of primary teeth with dental caries (${\chi}^2$=29.63, p<.01). 7. The frequency of taking caramel and candy was found to have statistically significant positive correlation with the number of primary teeth with dental caries (${\chi}^2$=38.85, p<.001). 8. The frequency of taking soft drinks was found to have statistically significant positive correlation with the number of primary teeth with dental caries (${\chi}^2$=52.92, p<.001). 9. The frequency of taking ice-creams was found to have statistically significant positive correlation with the number of primary teeth with dental caries (${\chi}^2$=75.07, p<.001). Conclusions : Those findings show that the children with undesirable dietary habit and higher frequency of taking snack have higher index of dental caries in primary teeth, therefore, it is considered that the regular brushing teeth and establishment of desirable dietary habit are very important for keeping health oral cavity. It is recommended that the continuous concern and repeated learning are needed in house and group of rearing infants so that the children take foods of fruits which have function of self-purification than the food of carbohydrates which has high adhesion and level of sweetness.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.4
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• pp.575-584
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• 2017

Previous research has investigated the influence of explicit self-esteem and depression. These studies did not examine the implicit self-esteem and depression that exist in the internal unconscious of humans that are not influenced by prejudice and social desirability. This study identifies that fashion competency (FC) encourages the implicit self-esteem and relieves the implicit depression. Implicit self-esteem and depression were measured by Implicit Association Test (IAT) utilizing reaction; FC was surveyed based on questionnaires. The data collected were analyzed using factor analysis. FC was then composed of three factors of fashion involvement, fashion innovativeness and self-confidence in fashion coordination. The results of comparing the index values that indicate IA SE (implicit association self-esteem) and IA DE (implicit association depression) of each FC group indicated that a higher FC results in a higher IA SE and lower IA DE; therefore, individuals with a higher fashion competence have a higher implicit self-esteem and a sense of well-being. The findings support previous studies in that the FC tends to be positively related to quality of life in young people.