• Journal of Information Processing Systems
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• 제16권6호
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• pp.1271-1280
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• 2020

The yield and quality of a micromanufacturing process are important management factors. In real-world situations, it is difficult to achieve a high yield from a manufacturing process because the products are produced through multiple nanoscale manufacturing processes. Therefore, it is necessary to identify the processes and equipment that lead to low yields. This paper proposes an analytical method to identify the processes and equipment that cause a defect in the plastic ball grid array (PBGA) during the manufacturing process using logistic regression and stepwise variable selection. The proposed method was tested with the lot trace records of a real work site. The records included the sequence of equipment that the lot had passed through and the number of faults of each type in the lot. We demonstrated that the test results reflect the real situation in a PBGA manufacturing process, and the major equipment parameters were then controlled to confirm the improvement in yield; the yield improved by approximately 20%.

• 응용통계연구
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• 제18권2호
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• pp.435-443
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• 2005

로지스틱 회귀모형에서 결정계수는 선형 회귀모형보다 다양하게 정의되며 그 값들도 매우 작아 로지스틱 회귀모형 평가기준으로 사용되는 통계량이 라고 할 수 없다. Liao와 McGee(2003)는 부적절한 설명변수의 추가 또는 표본크기의 변화에 민감하지 않은 두 종류의 수정 결정계수를 제안하였다. 본 연구에서는 실제자료에 적용한 로지스틱 회귀모형에서 수정 결정계수를 포함한 네 종류의 결정계수들을 변수선택의 기준으로 사용하여 기존의 변수선택 방법인 전진선택, 후진제거, 단계적 선택방법, AIC 통계량 등을 사용한 방법들과 비교하여 그 적절함과 효율성을 토론한다.

• 운동영양학회지
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• 제24권1호
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• pp.9-13
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• 2020

[Purpose] This preliminary study aimed to develop a regression model to estimate the resting metabolic rate (RMR) of young and middle-aged Koreans using various easy-to-measure dependent variables. [Methods] The RMR and the dependent variables for its estimation (e.g. age, height, body mass index, fat-free mass; FFM, fat mass, % body fat, systolic blood pressure, diastolic blood pressure, mean arterial pressure, pulse pressure, and resting heart rate) were measured in 53 young (male n = 18, female n = 16) and middle-aged (male n = 5, female n = 14) healthy adults. Statistical analysis was performed to develop an RMR estimation regression model using the stepwise regression method. [Results] We confirmed that FFM and age were important variables in both the regression models based on the regression coefficients. Mean explanatory power of RMR₁ regression models estimated only by FFM was 66.7% (R²) and 66.0% (adjusted R²), while mean standard errors of estimates (SEE) was 219.85 kcal/day. Additionally, mean explanatory power of RMR₂ regression models developed by FFM and age were 70.0% (R²) and 68.8% (adjusted R²), while the mean SEE was 210.64 kcal/day. There was no significant difference between the measured RMR by the canopy method using a metabolic gas analyzer and the predicted RMR by RMR₁ and RMR₂ equations. [Conclusion] This preliminary study developed a regression model to estimate the RMR of young and middle-age healthy Koreans. The regression model was as follows: RMR₁ = 24.383 × FFM + 634.310, RMR₂ = 23.691 × FFM - 5.745 × age + 852.341.

• Structural Engineering and Mechanics
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• 제66권6호
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• pp.677-691
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• 2018

Reliability assessment of complex structures using simulation methods is time-consuming. Thus, surrogate models are usually employed to reduce computational cost. AK-MCS is a surrogate-based Active learning method combining Kriging and Monte-Carlo Simulation for structural reliability analysis. This paper proposes three modifications of the AK-MCS method to reduce the number of calls to the performance function. The first modification is related to the definition of an initial Design of Experiments (DoE). In the original AK-MCS method, an initial DoE is created by a random selection of samples among the Monte Carlo population. Therefore, samples in the failure region have fewer chances to be selected, because a small number of samples are usually located in the failure region compared to the safe region. The proposed method in this paper is based on a uniform selection of samples in the predefined domain, so more samples may be selected from the failure region. Another important parameter in the AK-MCS method is the size of the initial DoE. The algorithm may not predict the exact limit state surface with an insufficient number of initial samples. Thus, the second modification of the AK-MCS method is proposed to overcome this problem. The third modification is relevant to the type of regression trend in the AK-MCS method. The original AK-MCS method uses an ordinary Kriging model, so the regression part of Kriging model is an unknown constant value. In this paper, the effect of regression trend in the AK-MCS method is investigated for a benchmark problem, and it is shown that the appropriate choice of regression type could reduce the number of calls to the performance function. A stepwise approach is also presented to select a suitable trend of the Kriging model. The numerical results show the effectiveness of the proposed modifications.

• 한국멀티미디어학회논문지
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• 제17권7호
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• pp.858-865
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• 2014

In the case of system like MES, various sensors collect the data in real time and save it as a big data to monitor the process. However, if there is big data mining in distributed computing system, whole processing process can be improved. In this paper, system to analyze the cause of operation deviation was built using the big data which has been collected from deasphalting process at the two different plants. By applying multivariate statistical analysis to the big data which has been collected through MES(Manufacturing Execution System), main cause of operation deviation was analyzed. We present the example of analyzing the operation deviation of deasphalting process using the big data which collected from MES by using multivariate statistics analysis method. As a result of regression analysis of the forward stepwise method, regression equation has been found which can explain 52% increase of performance compare to existing model. Through this suggested method, the existing petrochemical process can be replaced which is manual analysis method and has the risk of being subjective according to the tester. The new method can provide the objective analysis method based on numbers and statistic.

• 한국작물학회지
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• 제59권3호
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• pp.341-349
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• 2014

경실로 인해 다른 두과작물에 비해 포장 입묘가 불량한 팥의 포장출현율의 효과적인 예측 방법을 개발하기 위해 인위로 노화 정도를 조절한 종자에 대해 실험실에서 몇 가지 종자세 검사를 실시하여 포장출현력과 비교하였다. 얻어진 종자세 지표들에 대해 포장출현력과의 상관분석을 통해 예측을 위한 효율적인 지표들을 도출하였다. 팥에서 종자세가 높을 경우에는 표준발아검사에서의 종자활력률이 포장출현력 예측에 효과적이며, 약간 노화된 종자의 경우에는 저온발아검사(CGT)에서의 비정상묘율과 배축의 길이는 포장출현력과 높은 상관관계를 보였으며, 전기전도도와 CSVT에서의 활력률과 테트라졸리움 검사에서 종자세와 예측발아율은 포장출현력과 5% 수준에서 상관관계가 인정되었다. 종자세가 낮은 종자에서는 CSVT에서 불발아종자율이 포장출현력과 5% 수준에서 상관을 보였다. 포장출현력 예측에 효과적인 몇 가지 종자세지수를 이용하여 stepwise multiple regression 분석을 실시한 결과 테트라졸리움(TZ) 검사에서의 예측발아율은 결정계수($R^2$)가 0.820으로 포장출현력 예측에 가장 효과적인 검사방법임을 알 수 있었다. 표준발아검사(SGT)에서의 종자활력률, 저온발아검사(CGT)에서의 정상묘율과 건물중을 회귀방정식에 추가함에 따라 86.9% 까지 포장출현력 예측효율을 증가시킬 수 있었다.

• 한국습지학회지
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• 제18권3호
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• pp.301-312
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• 2016

본 연구는 낙동강수계 중점관리하천인 35개 지류 지천 수질 및 유량을 모니터링하고 수질오염농도, 발생부하량, 계절별 오염특성과 수질항목 간 상관관계 및 다중회귀분석을 실시하여 지류중심의 오염특성을 확인하였다. 그 결과 COD, TP, TOC 및 TN을 제외한 대부분의 하천에서 $BOD_5$, Chl_a 및 Fecal E. Coli 등은 50% 이상이 하천수질항목 II(약간좋음)등급 이하에 속하였다. 비유량(Q)은 $0.05m^3/s/km^2$ 이상 지점이 54.4%(19지점)를 차지하였고, 이 가운데 달서천, 현지천, 석교천1, 의령천1 및 대산천2 지점 등은 오염농도 역시 높아 오염물질부하량을 고려한 상세조사가 필요할 것으로 판단된다. 35개 중점관리지천은 낙동왜관, 금호강, 낙동고령, 낙동창녕, 남강, 낙동밀양 및 낙동강하구언 등 7개 중권역에 속하였으며, 이 가운데 금호강과 남강 중권역은 영천댐, 가창댐, 공산댐 및 남강댐과 같은 인공댐의 영향을 받아 다른 중권역과 달리 일정한 하천 유지유량을 보임으로써 오염물질부하량도 높게 조사되었다. 계절적 오염특성을 살펴볼 때, 농도편차가 큰 수질항목은 $BOD_5$, TN, SS, 비유량(Q)이, 큰 편차가 없는 항목은 TP와 Chl_a가 관찰되었고 이는 강우특성 및 유 무기물의 분해특성이 다르기 때문으로 판단된다. 이러한 결과를 바탕으로 계절별/수질항목 간 상관관계는 피어슨 상관계수(Pearson correlation coefficient)를 이용하여 분석하였고, 일부 항목을 제외한 모든 계절에서 TOC와 COD의 상관성이 높음을 확인하였다. 계절별 상관관계가 높은($R2{\geq}0.5$) 수질항목들이 $BOD_5$에 미치는 영향력을 알아보기 위해 단계선택방법(Stepwise regression method)을 이용한 다중회귀분석(Multiple regression analysis)을 실시함으로써 계절별 영향력이 높은 수질인자 및 회귀식을 제시하였다. 그 결과 겨울철을 제외한 봄, 여름 및 가을에 다중회귀분석이 적합하였고 봄철에는 COD, TP가, 여름철에는 Chl_a, TOC가 가을철에는 TOC 및 COD가 $BOD_5$에 영향력이 높음을 확인하였다.

• 수산경영론집
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• 제22권2호
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• pp.101-148
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• 1991

The fisheries cooperative (FC) performs the economic and nonprofitable activity to get the fundamental objective of enhancing cooperative members' economic and social position. The internal control system fitted for a local FC should be required for not only solving the resulting problem from the complexity of FC environment nowaday but also delegating authorities and performance from FC Federation to a local FC by implementing the local autonomy. The methodology of this study is to empirically test and to analyze the condition of FC internal control system (FCICS) by the questionnaire survey. The actual condition of FCICS in Korea is analyzed by the questionnaire and the detailed contents are as follows : (1) sending 208 questionnaire consisting of 162 questions, and receiving 92 replies from 39 manufactures (business firms) and 15 banks in Gyungnam and Pusan area and 25 FC and 13 agricultural cooperative (AC) in Korea, (2) the analyzed results of FC and AC are treated simultaneously. In the fundamentals of above analyzed results, the evaluation model of FCICS is tried to construct from the relationship between the financial condition of FC and the internal control elements through the stepwise regression method. (1) By the stepwise regression method, the number of FC officials $(X_1)$, the experimental number of regular auditing $(X_7)$, and auditing duty years $(X_8)$ are finally accepted as independent variables, (2) and the final model becomes $Y=-1.53526+0.34455X_1+0.24513X_7+0.16585X_8$/ and this model explains to the extent of 47.826%. From the above study, following proposals are to be suggested: (1) The function and problem of internal control in FCICS is able to be improved by enforcing the function of FCICS and enriching the management's recognition of FCICS (2) The cooperative president can bring up good FC by the rational operation of FCICS according to the size and the performance pattern of FC, adding up to enhance members' economic and social position.

• 한국학교보건학회지
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• 제18권1호
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• pp.71-82
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• 2005

Purpose: This study was undertaken in order to examine relations of eating disorders, health locus of control of college women, and to determine factors affecting eating disorders of college women. Method: The subjects were 282 students at a university in Busan. The instrument used for this study was a questionnaire on general characteristics, eating disorders (24 items), health locus of control (11 items) and self-esteem (10 items). Data were analyzed using means, percentages, t-test, ANOVA, Pearson correlation coefficients and stepwise multiple regression with a SPSS WIN 11.0 program. Result: Depending on BMI, there was no obese subject, 62.0% of the subjects were underweight, and 37.9% were normal. Over 40% of the subjects perceived them to be overweight while 62.1% of the women were underweight as defined by BMI. The total mean score of anorexia was higher than bulimia nervosa. There were significant differences in eating disorders according to BMI, perceived view of appearance, body satisfaction, experienced weight-control, and predictors of weight control method. Eating disorders showed a significant negative correlation with health locus of control and self-esteem. Stepwise multiple regression analysis revealed that the most powerful predictor of eating disorders was BMI. Experienced weight control, health locus of control and self-esteem and body appearance had significant effects on eating disorders. These predictive variables of eating disorders explained 27% of variance. Conclusion: The result of this study showed that eating behaviors among college women developed into eating disorders or were seriously disturbed. Therefore, to prevent eating disorders, health education should be provided to college women in relation to eating behaviors for health management.

• 디지털융복합연구
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• 제17권7호
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• pp.147-156
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• 2019

본 연구는 간호대학생의 자기효능감, 진로정체감, 전문직자아개념의 관계를 파악하기 위해 실시되었다. 간호대학생 3, 4학년 175명에게 설문조사 방법으로 자료 수집을 진행하였고, 분석방법은 stepwise multiple regression을 사용하였다. 분석 결과, 일반적 특성에 따른 전문직자아개념은 성별, 건강상태, 대인관계, 대학생활 만족도, 전공에 대한 만족도, 학업성적에 따라 통계적으로 유의한 것으로 확인되었다. 전문직자아개념에 대한 영향요인은 자기효능감, 진로정체감, 전공에 대한 만족도로 나타났고, 56.4%의 설명력을 나타냈다. 그러므로 신입생 때부터 자기효능감, 진로정체감, 전공에 대한 만족도를 향상시킬 수 있는 단계적인 중재 프로그램을 실시하여 간호대학생의 전문직자아개념을 강화시켜나가야 할 것이다.