• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.208-217
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• 2018

This study was designed to examine the influence of academic stress, anxiety, interpersonal dependency, and hopelessness on female high school students and their level of depression. The study subjects were 684 students attending an all-female high school in C city. Data were collected by self-administered questionnaires between November 1st, 2016 and December 31st, 2016. The data were analyzed using the SPSSWIN(ver. 21.0) program. The mean values of the level of depression were analyzed by the t-test and ANOVA. The correlation coefficientswereobtained by Pearson correlation analysis and acovariance structure analysis was performed on the factors affecting the level of depression. It was found that the level of depression among all of the subjects was significantly higher within the group with a higher level of academic stress, anxiety, interpersonal dependency, and hopelessness. Thus, the level of depression was positively correlated with the levels of academic stress, anxiety, interpersonal dependency, and hopelessness. The factor that had the most influence on depression was the anxiety factor, followed by interpersonal dependency and academic stress. This result suggests that the level of depression in female high school students has a causal relationship with academic stress, anxiety, interpersonal behavioral characteristics, and hopelessness. Therefore, the most effective strategy to reduce the level of depression among female high school students would appear to be efforts to decrease their academic stress, anxiety, and interpersonal dependency.

• The Korean Journal of Applied Statistics
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• v.17 no.1
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• pp.1-12
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• 2004

In this paper, we consider choosing the appropriate covariance structure for analyzing repeated measures data with three repeat factors from a study of blood pressure data, which is collected from the local residents of Yangpyeong, Gyeonggi-do (2001) and fitted linear mixed models to find the significant covariates on outcome variable(Blood Pressure)

• Management & Information Systems Review
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• v.12
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• pp.247-266
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• 2003

최근 인터넷 쇼핑몰에서 고객의 충성도에 관한 연구가 다양하게 이루어지고 있다. 또한 쇼핑몰 사용자의 경험적인 측면의 중요성이 제기되면서 많은 연구에서 이를 플로우란 개념으로 설명하고 있다. 본 연구는 인터넷 쇼핑몰에서의 최적 경험으로서의 플로우와 그 동안 인터넷 쇼핑몰 관련 연구에서 고객 충성도와의 긍정적 관계에 대해 논의가 있어온, 신뢰와 만족과의 관계를 공분산 구조 분석을 통해 경쟁 모델화 하여 비교함으로써 우수 모델을 도출하였다. 그 결과 플로우와 신뢰, 만족, 충성도간의 관계를 모두 고려한 포화모델이 우수한 모델로 도출되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4995-5004
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• 2011

This study was performed to determine the levels of depressive symptoms among community elderlies and to reveal its related factors, specifically aimed at revealing factors such as social support, family support and physical function. The interviews were performed, during the period from April 1st, to June 30th, 2010, to 995 elderlies in Daejeon city. As a results, social support, family support, ADL and IADL was found to be in a positive correlation with depressive symptoms. With the analysis of covariance structure, social support was more influential on the level of depressive symptom than family support and physical function. It was found to have the inter-relational effects that the greater the social support, family support and physical function, the lower the level of depressive symptoms.

• Korean Journal of Optics and Photonics
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• v.30 no.3
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• pp.87-93
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• 2019

Phase screens are widely used to simulate the effects of atmospheric turbulence on the phase fluctuations of a light beam. We compare three sampled-based phase-screen-generation methods (the fast-Fourier-transform, subharmonic, and covariance-matrix methods), in terms of accuracy and simulation time. We show that the covariance method generates the phase screens most accurately, with simulation time comparable to the other sampled-based methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.629-640
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• 2016

This study was conducted to investigate the influence of job stress, fatigue symptoms and job satisfaction on turnover intention among dental hygienists. Overall, 516 dental hygienists who work in dental clinics were surveyed using a standardized self-administered questionnaire from April 1 to June 30, 2015. Mean turnover intention was compared to each independent variable tested by t-tests and ANOVA, correlation among turnover intention, job stress, fatigue symptoms and job satisfaction was calculated by Pearson's correlation coefficient, and covariance structure analysis was used to evaluate whether turnover intention was associated with job stress, fatigue symptoms and job satisfaction. Turnover intention was significantly higher among subjects with higher job stress and fatigue, as well as those with lower job satisfaction. Additionally, turnover intention was significantly positively correlated with job stress and fatigue symptoms, while turnover intention was negatively correlated with job satisfaction. Covariance structure analysis revealed job stress had a greater impact on turnover intention than fatigue and job satisfaction, high job stress and fatigue, the lower the job satisfaction showed that the effect of increasing the turnover intention. Overall, these results indicate that turnover intention of dental hygienists are more heavily influenced by job satisfaction and job stress than fatigue. Therefore, efforts are needed to reduce job stress and fatigue, as well as to improve job satisfaction to reduce the degree of turnover intention among dental hygienists.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.256-256
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• 2022

레이놀즈 분해법은 유속을 비롯한 변수를 평균 성분과 변동 성분으로 분해하는 분석 방법으로, 난류 분석의 기본이 되는 방법이다. 그러나 유체 내에 장애물이 존재할 경우, 흐름에 큰 와류가 존재하여 난류 변동 성분과 구분되는 고유 구조가 형성되는데, 이러한 경우에 레이놀즈 분해법을 적용하면 고유 구조의 변동 성분이 난류로 처리되어 난류 강도가 과다하게 책정될 수 있다는 한계점이 있다. 이에 대한 대안으로 제안된 것이, 변수를 평균 성분, 파동 성분, 변동 성분으로 분해하는 삼중 분해법이다. 삼중 분해법은 흐름 내의 고유 구조를 추출하는 것을 가능하게 하여 다양한 연구에서 사용되어왔다. 삼중 분해법을 구현하기 위해 이용되는 방법론 중 하나로, 공분산 행렬을 이용하여 유속장을 분해하는 방법인 적합 직교 분해법이 많이 사용된다. 본 연구에서는 원기둥 후류에 적합 직교 분해법을 사용하여 삼중 분해법을 시행하고, 후류의 흐름 구조를 분석하는 것을 목표로 하였다. 영상 유속계를 사용하여 실험을 통해 원기둥 후류의 수평 유속장을 측정하였고, 측정 자료에 적합 직교 분해법을 적용한 결과, 첫 두 모드에서 큰 규모의 와류가 파동 형태로 전파되는 것이 관찰되어 고유 구조의 존재를 확인할 수 있었다. 해당 성분을 삼중 분해법의 파동 성분으로 상정하였고, 푸리에 분석을 적용한 결과에서도 원기둥 후류의 고유 진동수가 뚜렷하게 나타나는 것을 확인하였다. 또한, 원기둥 후류의 에너지 전달 구조를 확인하기 위하여 에너지 방정식에 삼중 분해법을 적용하여 식을 유도하고, 실험 자료로부터 각 항을 계산하여 비교해보았다.

• The Korean Journal of Applied Statistics
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• v.21 no.2
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• pp.291-299
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• 2008

This paper discusses model building for repeated binary response data with different time-dependent covariates each occasion. Since repeated measurements data are having correlated structure, weighed least squares(WLS) methodology is applied. Repeated measures designs are usually having different sizes of experimental units like split-plot designs. However repeated measures designs differ from split-plot designs in that the levels of one or more factors cannot be randomly assigned to one or more of the sizes of experimental units in the experiment. In this case, the levels of time cannot be assigned at random to the time intervals. Because of this nonrandom assignment, the errors corresponding to the respective experimental units may have a covariance matrix. So, the estimates of effects included in a suggested logit model are obtained by using covariance structures.

• Proceedings of the Korea Contents Association Conference
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• 2012.05a
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• pp.213-214
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• 2012

항공규제완화법과 더불어 항공 협정에 의한 자유경쟁 체제의 돌입과 함께 급성장한 항공운송시장에서 항공사간의 경쟁이 불가피해졌고 이에 각 항공사들은 경쟁력을 갖추기 위해 고객의 유치뿐만 아니라 경쟁사와의 차별화를 둔 새로운 경영 전략을 수립 및 추구해 나가고 있는 실정이다. 본 연구에서는 충성 고객 증진 및 그 보유 방안을 모색하기 위하여 국내 저비용항공사 이용 고객을 대상으로 항공사 선택 속성에 영향을 미칠 수 있는 요인들 중 가격, 서비스, 금전 가치, 감정가치, 만족, 신뢰 및 충성도라는 변수들에 대하여 실증 연구를 통한 분석으로 그 유의성을 알아보고자 한다. 가설 및 연구 모형 검증을 위해 SPSS와 AMOS 프로그램의 활용 및 빈도 분석, 요인 분석, 신뢰도 검정 그리고 공분산 구조 방정식 분석 등의 통계기법을 이용하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.17-27
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• 2014

As the importance of Cooperative Engagement Capability and network-centric warfare has been dramatically increasing, it is necessary to develop distributed tracking systems. Under the development of distributed tracking systems, it requires tracking filters and data fusion theory for nonlinear systems. Therefore, in this paper, the problem of nonlinear track fusion, which is suitable for distributed networks, is formulated, four algorithms to solve the problem of nonlinear track fusion are introduced, and performance of introduced algorithms are analyzed. It is a main problem of nonlinear track fusion that cross-covarinaces among multiple platforms are unknown. Thus, in order to solve the problem, two techniques are introduced; a simplification technique and a approximation technique. The simplification technique that help to ignore cross-covariances includes two algorithms, i.e. the sample mean algorithm and the Millman formula algorithm, and the approximation technique to obtain approximated cross-covariances utilizes two approaches, by using analytical linearization and statistical linearization based on the sigma point approach. In simulations, BCS fusion is the most efficient scheme because it reduces RMSE by approximating cross-covariances with low complexity.