• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.723-726
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• 2019

사람은 한 장소를 방문할 때 순환 패턴이 있으며, 이 패턴에 여러 싸이클의 경향이 있다. 요즘은 스마트폰 및 기타 휴대용 장치로 개인 이동성 데이터를 수집하는 것이 가능하다. 이러한 장치는 다양한 위치 데이터를 수집하고 여러가지 방법으로 분석할 수 있게 해준다. 위치 수집기를 기반으로 지구 위치 데이터에서 추출된 사람의 이동성 모델을 수립하고, 위치 클러스터를 방문자의 순환 패턴을 조사할 수 있다. 수년 동안 수집된 개인의 이동성 모델을 토대로 클러스터 재방문 시간을 계산 후 분석하여 그래프로 시각화하였다. 시간 순서의 위치 클러스터와 방문 클러스터에 대한 위치 데이터는 1 분 단위로 측정된다. 전체 데이터 방문 횟수는 15 분마다 정규화하고, 자원 봉사자의 다양한 지리적 위치 데이터 셋에 대해 방문의 순환 패턴은 자기 상관, 자기 공분산 및 재방문 시간으로 살펴볼 수 있다.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.403-408
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• 2005

The techniques of estimating angle of arrival(AOA) have played a key role for enhancement of wireless communications using array antennas. Among those techniques, the superresolution algorithms, such as MUSIC and ESPRIT, calculate the covariance matrix of the array output vectors which are observed at the array antennas, and then by using eigen-decomposition of the covariance matrix, they estimate AOAs of the received signals with high accuracy. However, superresolution algorithms based eigenvalue decomposition fails to estimate AOAs under multipath environments. Under multipath environments, it is difficult to estimate AOAs of the received signals due to coherency and high-correlation. To resolve coherent signals, the covariance matrix is calculated by using the conventional spatial smoothing technique, and then the techniques based on eigen-descomposition is applied. The result of the conventional spatial smoothing technique, however, is obtained at the cost of losing effective spatial aperture. Moreover, the conventional technique ignores any information in the cross-correlations of the array outputs the subarrays. As the result, the performance for AOA estimation is degraded. In this paper, we propose a new spatial smoothing technique, which consider the cross-correlation for subarrays. By computer simulation, the AOA estimation performance of the proposed method is compared with the conventional method and evaluated.

• The Korean Journal of Applied Statistics
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• v.36 no.1
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• pp.21-32
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• 2023

The amount of money processed in medicine from the Korea Consumer Agency was studied by the various time series models. The medical data set from the Korea Consumer Agency were consisted of counseling, damage relief and conciliation. For the analysis of time series, autoregressive moving average model, vector autoregressive model and the transfer function model were used. We considered the stationarity and cross correlation function for the identification and fitting. As a result, the transfer function model showed a better prediction. Whereas, the vector autoregressive model also provided good information for the degree and duration of the influence of variables.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2513-2515
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• 2004

본 논문에서는 주어진 데이터를 나누어 부분공간으로 구성하여 특성을 구분하거나 또다른 모델의 입력 파라미터로 제공하는 방법 중 하나의 클러스터링의 성능 개선과 이를 이용하여 퍼지 모델링을 실시하였다. 일반적인 클러스터링에서 볼 수 있는 초기 파라미터 결정 문제와 알고리즘의 수렴 문제에 대하여 문제점을 개선하였으며 클러스터링에 의하여 추정된 파라미터를 퍼지 모델에 적용하였다. 또한 일반적인 퍼지 모델의 경우 각 입력의 차원이 서로 독립적으로 구성되어 있어 데이터에서 존재하는 입력간의 상관관계를 고려하지 않았다. 제안된 퍼지 모델에서는 클러스터링에서 추정된 입력간의 상관관계(공분산)까지 고려하여 모델의 성능을 개선하였다. 제안된 논문의 유용성을 시뮬레이션을 통하여 보이고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.209-218
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• 2017

This study examined the influence of social support (social support from family, social support from friends), psychological behavioral characteristics (self-esteem, interpersonal dependency, locus of control), and stress on the depression levels of college students. The study subjects were 546 college students in D city. The survey was conducted using a self-administered questionnaire in October 2015. As a result, the depression levels were significantly higher in the group showing lower family and friends' social support, self-esteem, and locus of control, while it was significantly higher in the group showing higher interpersonal dependency and stress. The depression levels of the subjects showed a negative correlation with family and friends' social support, self-esteem, and locus of control, but a positive correlation with interpersonal dependency and stress. Covariance structure analysis revealed an increase in the depression levels of college students when the awareness of the stress source was higher, and when the awareness of social support or psychological behavioral characteristics was lower. These results suggest that the depression levels of college students would be increased when the social support and psychological behavioral characteristics are low, and when stress is high. In particular, it was influenced much more by stress than other factors. Therefore, to decrease the depression levels of college students, it would be necessary to put efforts to understand their main stress sources and then reduce them.

• 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.

• Journal of the Korean Chemical Society
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• v.56 no.5
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• pp.648-657
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• 2012

This study is examined for the effects of question generating strategy and feedback(teacher feedback and student peer reviews) on science achievement, self-efficiency and perception of the class in the middle school. Three classes of middle school 1st grade in a city were sampled for the study. The students in comparative group took traditional lessons and solved questions presented on worksheets distributed by a teacher. On the other hand, the students in the experimental groups 1 and 2 generated and solved questions by themselves after traditional lessons and then participated in the activity with peer's feedback and teacher's feedback, respectively. A self-efficiency test had been conducted before the treatments and the various tests such as achievement, self-efficiency and the perception of the class were carried out after treatments. The statistical results were analysed by ANCOVA, MANCOVA and t-test. The results of this study were as follows: First, there was significant difference between the control and experimental groups in the science achievement test (p<.01). But there was no significant difference between the experimental groups (p>.05). Second, both of the experimental groups showed enhanced self-efficiency compared with comparative group (p<.01). In sub-areas of self-efficiency, there were also meaningful results in the area of self-efficiency for control experimental group 1(p<.01), and in the area of difficulty preferences for experimental group 2 (p<.01). Third, the experimental group 1, given teacher's feedback, showed more positive perception of the class than the experimental group 2 that was given peer's feedback (p<.01).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7126-7137
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• 2015

This study explored the quality of nursing services in relation to a nurse's psychosocial factors (type A behavior pattern, self-esteem, locus of control, and anxiety), job stress, and fatigue. This study targeted 503 nurses who currently work at six different general hospitals in Daejeon city, The data was collected by self-administered questionnaire which was surveyed from April 1 to June 30, 2014. As the result of analysis of covariance, psychosocial factors affect the quality of nursing services more than job stress or fatigue. In addition to that, as parts of psychosocial factors, high self-esteem and low fatigue, job stress, and anxiety increase the quality of nursing services. The research above implies that the quality of nursing services of nurses who work at the general hospital has a correlation with not only the psychosocial factors but also job stress, and fatigue.

• Culinary science and hospitality research
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• v.16 no.4
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• pp.94-110
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• 2010

The purpose of this study is to how certain types of leadership of food and beverage employees in the super deluxe hotels in Seoul significantly affect self-efficacy, organizational efficacy and organizational effectiveness. The model was tested using SPSS 12.0 and AMOS 5.0 on a sample of 222 respondents with 74% of a usable response nate. The result of ANCOVA indicates idealized influence, individualized consideration and intellectual stimulation, which are the characteristics of transformational leaders, significantly and positively influence the organizational-efficacy, job satisfaction and organizational commitment Individualized consideration and intellectual stimulation significantly influence self-efficacy. Self-efficacy significantly influence. Organizational efficacy, and it also indirectly influence organizational commitment through job satisfaction. Organizational efficacy bas a significant relationship with organizational commitment through job satisfaction while it doesn't have a direct effect on organizational commitment.

• 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.