• Sleep Medicine and Psychophysiology
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• v.14 no.1
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• pp.42-48
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• 2007

Introduction: Detrended fluctuation analysis (DFA) is used as a way of studying nonlinearity of EEG. In this study, DFA is applied on sleep EEG of normal subjects to look into its nonlinearity in terms of EEG channels and sleep stages. Method: Twelve healthy young subjects (age：$23.8{\pm}2.5$ years old, male：female=7：5) have undergone nocturnal polysomnography (nPSG). EEG from nPSG was classified in terms of its channels and sleep stages and was analyzed by DFA. Scaling exponents (SEs) yielded by DFA were compared using linear mixed model analysis. Results: Scaling exponents (SEs) of sleep EEG were distributed around 1 showing long term temporal correlation and self-similarity. SE of C3 channel was bigger than that of O1 channel. As sleep stage progressed from stage 1 to slow wave sleep, SE increased accordingly. SE of stage REM sleep did not show significant difference when compared with that of stage 1 sleep. Conclusion: SEs of Normal sleep EEG showed nonlinear characteristic with scale-free fluctuation, long-range temporal correlation, self-similarity and self-organized criticality. SE from DFA differentiated sleep stages and EEG channels. It can be a useful tool in the research with sleep EEG.

• Anxiety and mood
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• v.6 no.1
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• pp.45-54
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• 2010

Objective : This study aimed to investigate and compare the prevalence of depression and suicidality among the elderly in a rural city according to their residence type. Methods : Participants were 311 elderly people (109 male and 202 female) in Icheon City, whom trained researchers interviewed and examined Geriatric Depression Scale, Social Support Scale, Instrumental Activities of Daily Living, Activities of Daily Living, Quality of Life Scale, and Mini International Neuropsychiatric Interview (MINI), module C. Using these data, we analyzed participants' risk factors associated with depression and suicidality. Results : The prevalence of depression was 28.0%. The prevalence in the elderly living alone and those admitted to residential facilities was significantly higher than that among the elderly living with family. Suicidality frequency was 19.6%. The suicidality frequency among the elderly living alone and those admitted to facilities was significantly higher than that among the elderly living with family. The risk factors for depression were age, admission to a facility, and low economic status. The suicidality risk factors were living alone, admission to a facility, poor social support, and a history of headache. Conclusion : These results showed the prevalence of depression and frequency of suicidality among the elderly in such a city was quite high. The results of this study remind psychiatrists of the importance of early detection and therapeutic intervention for the elderly with a high risk of depression and suicidality.

• The Journal of the Korea Contents Association
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• v.19 no.1
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• pp.47-59
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• 2019

The purpose of this study was to investigate the relationship between demographic characteristics, self - esteem, and attachment instability (attachment anxiety, attachment avoidance) in the college students' SNS addiction tendency. To investigate the influencing factors on SNS addiction tendency of college students, we surveyed 330 college students at universities in the metropolitan area through offline and online questionnaires, and analyzed 271 valid ones. Frequency analysis, descriptive statistics, variance analysis, Pearson correlation analysis and multiple regression analysis were performed. The results of the analysis are as follows. First, 87.4% of college students used SNS, and the most used SNS was 'Facebook (82.3%)'. The most frequent use of SNS per day was 'over 1 hour ~ less than 2 hours (24.7%)'. Second, women had a significantly higher SNS addiction tendency than men. Third, self-esteem and SNS addiction tendency showed significant negative correlation. Fourth, attachment anxiety and attachment avoidance were positively correlated with SNS addiction tendency. Fifth, the self-esteem of college students affects negatively on the SNS addiction tendency and only the attachment anxiety among attachment instability affects the addiction tendency. Finally, we discussed the risk of SNS addiction according to the characteristics of university students.

• Journal of Digital Convergence
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• v.20 no.4
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• pp.499-512
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• 2022

The purpose of this study was to first look at genderless concepts that are different from Unix, and by grasping the trend of genderless clothes in modern fashion and examining their characteristics, we looked at genderless trends and characteristics in modern fashion. To this end, this study conducted a theoretical review and collection case analysis through domestic and foreign literature and fashion websites. Based on this, the characteristics of genderless clothes expressed in the collection were derived by analyzing designs with strong genderless tendencies in modern collections. As a result of the study, genderless fashion in modern collections could be derived from three visible results: innovation, rebellion, and future-oriented. In addition, modern genderless fashion contains various needs for mental gender and physiological gender, not simply physiological gender, and this is seen by interacting with the current social phenomenon in which gender distinction becomes ambiguous. Understanding and studying the genderless phenomenon, which has become a cultural phenomenon and popularity, hopes that many follow-up studies related to genderless clothes will be conducted in the future.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.1023-1028
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• 2018

Mechanical gears driven by direct contact have problems including noise, vibration and heat. In order to, solve these problems, magnetic gears having a non-contact magnetic coupling have been proposed. Through various studies on magnetic gears, we found that losses are changed when the number of magnetic poles varies in the same gear ratio. For this reason, research team expect the iron loss of the magnetic gear and the Eddy current loss of the permanent magnet will have a certain tendency depending on the number of poles. This paper identified the magnetic gear's loss tendency according to the number of poles, and laid the basis for efficiency improvement design.

• The Korean Journal of Applied Statistics
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• v.36 no.5
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• pp.399-413
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• 2023

Recently, monitoring and detecting anomalies in social networks have become an interesting research topic. In this study, we investigate the detection of abnormal changes in a network modeled by the DCSBM (degree corrected stochastic block model), which reflects the propensity of both individuals and communities. To this end, we propose three methods for anomaly detection in the DCSBM networks: One method for monitoring the entire network, and two methods for dividing and monitoring the network in consideration of communities. To compare these anomaly detection methods, we design and perform simulations. The simulation results show that the method for monitoring networks divided by communities has good performance.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.13 no.6
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• pp.117-127
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• 2018

When we face an unexpected challenge, should we stick to the original plan and persevere through the series of challenges? Or shall we pivot and transform our original plan into something new by taking into account the newly acquired information? This perennial question of perseverance versus pivot as two competing problem-solving strategies has puzzled our every day lives. In this study, based on the large-scale, nation-wide survey on entrepreneurship, I found that individual entrepreneurial orientation, which consists of innovativeness, risk-taking, and proactiveness, promotes an individual's tendency to choose new problems to solve. Perseverance strategy was found to positively moderates the relationship between innovativeness and the tendency to choose new problems to solve, whereas the relationship between risk-taking and the tendency to choose new problems to solve was found to be negatively moderated by perseverance strategy. Pivot strategy, on the other hand, was found to be positively moderates the relationship between proactiveness and the tendency to choose new problems to solve. These findings contributes to the stream of individual entrepreneurial orientation research by empirically testing two competing problem-solving strategies of perseverance and pivot to show their interaction effects with entrepreneurial orientation. Also the findings of this study expand the potential outcome of entrepreneurial orientation by adding an individual's tendency to choose new problems to solve rather than what he or she has already experienced before.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1998.10a
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• pp.563-568
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• 1998

응용시스템 개발생산성에 대한 연구는 지금까지 프로그래머의 생산성이라는 미시적 수준에 그치는 경향을 보여왔으며 시스템개발 생명주기의 전반적 영향에 중점을 둔 거시적수준의 생산성의 개념으로 확대되지 못해왔다. 더욱이 그들의 생산성 측정은 미시적 측정단위를 사용함으로써 조직 내 응용시스템 개발요구의 백로그의 증가라는 거시적 문제 해결과는 거리가 있어왔다. 본 연구는 정보시스템 조직의 생산성 향상에 기여할 수 있는 도구 및 방법이 실무적으로 어떻게 사용되고 있고 그 효과가 어느 정도인지를 관찰하는 탐색적 연구로써 응용 시스템 개발 생산성에 기술적 방법과 관리적 방법을 거시적 생산성 향상의 관점에서 분석하고자 한다.

• Proceedings of the Korea Society of Design Studies Conference
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• 2000.11a
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• pp.100-101
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• 2000

본 연구는 현대의 다원화, 다양화되어가는 디자인의 경향을 사회의 변화에 비추어 그 원인을 찾아보고, 다각적인 분석을 통하여 앞으로 디자인의 변화, 전개방향을 예측해 보는 것을 목적으로 한다. 많은 동인(죄B3)들로부터 여러 가지 다양한 변화양태들이 드러나고 있지만, 본 연구에서는 그 중에서도 두드러진 양상인 비실제성과 감성에 초점을 맞추고, 이를 사회, 문화의 변화에 비추어 살펴보고자 한다.(중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.269-277
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• 2016

This study aims to grasp the influence of a college student's academic emotions and the ability of interpersonal relations according to gender on the SNS addiction tendency. Data were collected through a self-reported structured questionnaire from 130 college students using convenient sampling methods from September 1 to October 31, 2015. The research result showed that in the case of male college students, only the ability of interpersonal relations (${\beta}=-.41$, p=.009) was understood as a variable with an influence on the SNS addiction tendency, having approximately 16% power of explanation (F=2.26, p=.049) after controlling for age, daily average duration of using SNS, subjectively-perceived level of dependence on SNS, and one's own level of using SNS. In the case of female college students, it was understood that the daily average duration of using SNS (${\beta}=.42$, p<.001) and positive academic emotions(${\beta}=.27$, p=.010) were variables having an influence on the SNS addiction tendency, having approximately 28% power of explanation (F=5.19, p<.001). Accordingly, to solve the psycho-social health problems related to male and female students' SNS addiction based on this research, it might be helpful for planning a program by taking into account the differences between the related variables according to gender.