• International Journal of Fuzzy Logic and Intelligent Systems
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• 제5권3호
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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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• 제9권4호
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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.

• 응용통계연구
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• 제15권1호
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• pp.165-177
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• 2002

이 논문은 과학기술을 진흥시키기 위한 국가적 차원의 연구사업들이 과학기술자를 양성하기 위하여 어느 정도 기여하고 있는가를 평가하기 위한 인력양성지수를 제안하는 것이 주요 내용이다. 인력양성지수에 영향을 주는 요인으로는 대학원생(연구조원) 수, 연구조원 중에서 석·박사 학위 취득자 수와 취업자 수, 발표논문 수 등이다. 제안된 인력 양성지수에 의하여 과학재단의 우수연구센터 사업, 지역협력 연구센타 사업, 목적기초 연구 사업 등의 인력양성 기여도를 분석하였다. 이 사업들은 전반적으로 약간의 차이는 있으나 상당부분 인력양성에 기여하고 있음을 보여주고 있다.

• Communications for Statistical Applications and Methods
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• 제10권2호
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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,$\rho$).

• 한국CDE학회논문집
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• 제18권5호
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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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• 제18권3호
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• pp.377-389
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• 2011

공정능력지수는 공정능력을 측정하고 분석하기 위하여 매우 중요한 역할을 하는 측도로, 품질수준과 밀접한 관계가 있을 뿐만 아니라 보다 높은 품질수준은 고객들에게 더 큰 만족을 가져다 준다. 제3세대 공정 능력지수 $C_{pmk}$는 gms히 6시그마 산업현장에서 공정능력을 평가하기 위하여 유용하게 사용되는 두 가지 지수 $C_p$와 $C_{pk}$보다 이론적으로 강력한 지수이다. 실제로 제조현장에서 두 가지 이상의 서로 연관이 있는 품질특성치들과 제품에 대한 규격한계들을 사용하여 보다 정확한 공정능력 분석이 필요할 것이다. 이러한 경우에 단순히 하나의 일변량 공정능력지수를 통하여 공정능력분석을 하기 보다는 벡터 공정능력지수나 다변량공정능력지수를 통하여 분석을 수행하는 것이 바람직할 것이다. 본 논문에서는 3세대 공정능력지수 $C_{pmk}$를 고려하여 2차원 벡터 공정능력지수 $C_{pmk}$ = ($C_{pmkx}$, $C_{pmky}$)$^t$에 대하여 연구하였다. 우선, $C_{pmk}$에 대한 플러그-인(plug-in) 추정량 $\hat{C}_{pmk}$과 관련하여 핵심내용인 극한 확률분포를 유도하였다. 나아가 이러한 결과를 기초로 이변량 정규분포하에서 공분산 행렬 $V_{pmk}$을 구체적으로 계산하였다. 또한 이 행렬의 추정을 통하여 벡터 공정능력지수 $C_{pmk}$에 대한 근사적인 공동 신뢰영역을 제시함으로써, 본 논문에서의 극한분포 연구결과가 벡터 공정능력지수 $C_{pmk}$에 대한 통계적 추론에 유용하게 활용될 수 있음을 보여주었다.

• 한국식품영양과학회지
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• 제32권8호
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• pp.1270-1277
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• 2003

두유박과 옥분 혼합물의 압출성형물을 제조하기 위한 공정 조건의 위하여 스크류 속도 150∼250 rpm, 혼합물의 수분함량 20∼30%, 온도 100∼15$0^{\circ}C$의 조건에서 압출 성형하고, 반응표면분석법 (RSM)을 이용하여 최적 조건을 분석하였다. 공정 조건에 따른 팽화율에서는 스크류 속도가 높고 수분함량이 낮을수록 팽화가 크게 일어났고, 수분함량이 많을수록 용적 밀도를 높이는 것으로 나타났다. 절단강도의 경우 수분 함량에 따라 감소하다 증가하는 추세를 보여주었고, WSI는 스크류 속도와 수분함량에 WAI는 수분함량과 온도에 많은 영향을 받았다. 색도에서는 b＊ 값을 제외하고는 유의적인 차이를 보이지 않았다. 각 조건별 실험결과를 반응표면분석을 한 결과 팽화율과 용적 밀도, WSI, b＊ 값은 linear모델로 결정되었고, 절단강도와 WAI는 quadratic 모델이 유의성을 나타내었다. 압출 성형 공정의 최적화는 결정된 반응식과 반응표면 그래프를 이용한 결과 수치 최적화에서는 스크류 속도 250 rpm, 수분함량 22.43%, 온도 128.16$^{\circ}C$이었고, 모형적 최적화에서는 desirability가 0.727인 스크류 속도 250 rpm, 수분함량 22.43%, 온도 128.02$^{\circ}C$로 결정되었다.

• 대한치과교정학회지
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• 제43권1호
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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.

• 한국치위생학회지
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• 제10권2호
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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.

• 한국의류학회지
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• 제41권4호
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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.