• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.62-67
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• 1999

In this letter, a scheme for increasing the input power dynamic range of wavelength converters based on cross-gain modulation (XGM) in semiconductor optical amplifiers (SOA/s) is proposed. We investigate the effect of input pump and probe powers on the power penalty, the measure of performance for the wavelength converters. As a result, we show that the optimal bit error rate (BER) performance can be obtained when the probe power is kept 3 dB weaker than the pump power. Using this characteristic, we propose the wavelength converter scheme that controls the probe power level by monitoring the input pump power and adjusting the bias current of probe source accordingly. Consequently, the wavelength converter for wide input power dynamic range can be implemented. We show that an input power dynamic range of more than 20 dB at 2.5 Gb/s is achievable.

• Sleep Medicine and Psychophysiology
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• v.17 no.2
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• pp.100-108
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• 2010

Objectives: "Internet-addiction" came into common use not only in clinical setting but also in everyday life. But, pathophysiology and diagnostic criteria of the internet addiction remain unknown. Because adolescents are in developing period, they might be vulnerable to the internet addiction, depression and sleep-related problem. The objectives of this study were to investigate the characteristics of internet addiction and its association with sleep pattern and depression in Korean adolescence. Methods: Subjects were 799 middle and high school students in Seoul, Korea. We administered a self-reported questionnaire including socio-demographic data, Korean versions of Young's Internet Addiction Scale (YIAS), Pittsburgh Sleep Quality Index (PS-QI), the Center for Epidemiologic Studies for Depression Scale (CES-D) and questions about internet using patterns. Data of 696 subjects were included in analysis. Chi-square tests were used to analyze proportional differences, and ANOVA with post-hoc tests were used to analyze differences among groups. Partial correlation analyses were performed to analyze the correlation of internet addiction with other variables (two-tailed, p<0.05). Results: Of the 696 participants (grade 2 of middle school; M2 135 vs. grade 1 of high school; H1 238 vs. grade 2 of high school; H2 323), 2.0% (n=14) were internet-addicted (IA), 27.7% (n=193) were over-using (OU) and 70.3% (n=489) were not-addicted (NA). The mean scores of YIAS, PSQI and CES-D scores were 35.24${\pm}$12.78, 5.53${\pm}$3.04 and 16.72${\pm}$8.69, respectively. In higher grade students, average total sleep time was shorter (M2 426.20${\pm}$67.68 min. vs. H1 380.47${\pm}$62.57 min. vs. H2 354.67${\pm}$73.37 min., F=51.909, p<0.001), and PSQI (4.69${\pm}$3.14 vs. 5.42${\pm}$3.15 vs. 5.97${\pm}$2.83, F=8.871, p<0.001) CES-D (13.53${\pm}$8.37 vs. 16.96${\pm}$8.24 vs. 17.87${\pm}$8.84, F=12.373, p<0.001) scores were higher than those of lower grade students. Comparing variables among IA, OU and NA groups, computer using time not for study (96.36${\pm}$63.31 min. vs. 134.92${\pm}$86.79 min. vs. 213.57${\pm}$136.87 min., F=34.287, p<0.001) and portable device using time not for study (84.22${\pm}$79.11 min. vs. 96.97${\pm}$91.89 min. vs. 152.31${\pm}$93.64 min., F= 5.400, p=0.005) were different among groups. PSQI (5.26${\pm}$2.97 vs. 6.08${\pm}$2.97 vs. 7.50${\pm}$4.41, F=8.218, p<0.001) and CES-D scores (15.40${\pm}$8.08 vs. 19.05${\pm}$8.42 vs. 30.43${\pm}$13.69, F=32.692, p<0.001) were also different among groups. YIAS score were correlated with computer using time not for study (r=0.356, p<0.001) and portable device using time not for study (r= 0.136, p<0.001). PSQI score (r=0.237, p<0.001) and CES-D score (r=0.332, p<0.001). YIAS score and PSQI score (r=0.131, p= 0.001), YIAS and CES-D score (r=0.265, p<0.001), PSQI score and CES-D score (r=0.357, p<0.001) were correlated each other. Conclusion: These results suggested that adolescents' internet-addiction was correlated with not only computer and portable device using time not for study but also depression and sleep-related problems. We should pay attention to depression and sleep-related problems, when evaluating internet-addiction in adolescents.

• Journal of Digital Convergence
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• v.14 no.5
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• pp.485-491
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• 2016

The purpose of this study was to compare of the fall risk factors for elderly in the city. 62 people aged 65 years or older were classified as fallers and nonfallers based on experience of their falls in the previous year. By comparing the difference between the groups via evaluations of general characteristics, health related behavior and chronic disease, balance-related psychological (K-ABC) and physical measurement (BBS), depression (SGDS), and the correlations between the significant differences in variables were identified. According to the results, K-ABC, BBS, and SGDS are statistically significant differences between fallers and nonfallers (P<0.05). Also it has positive correlations between BBS and K-ABC (r=0.499) whereas negative correlation between K-ABC and SGDS(r=-0.472).

• Korean Journal of Psychosomatic Medicine
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• v.29 no.2
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• pp.191-198
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• 2021

Objectives : This study was designed to investigate the correlation between defense mechanism and posttraumatic stress disorder in burn patients. Methods : We recruit 40 burn patients and we evaluate sociodemographic characteristics, characteristics related to burn, korean version of Impact of Event Scale-Revised (IES-R), Korean Version of Center for epidemiologic studies depression scale (CES-D) and Ewha Defense Mechanisms Test (EDMT). Multiple regression analysis was performed to evaluate the correlation between EDMT score and IES-R score. Results : Factor 2 of EDMT which consists of Ego-expansion subjects was significantly correlate with IER-S score. In factor 2, Controlling (β=-0.299, p<0.05), Sublimation (β=-0.276, p<0.05) is significantly correlate with IER-S score. Conclusions : Some subjects of defense mechanism was significantly correlate with IES-R score. it might be helpful to understand defense mechanism for the posttraumatic stress disorder in burn patients.

• Journal of the Korea Institute of Building Construction
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• v.20 no.2
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• pp.171-181
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• 2020

Recently, free-formed construction technology is becoming a new measure of representing technological superiority and sociocultural ingenuity. However, the CNC processing technology utilizing the existing wood and iron form has limitations in terms of the manufacturing time and material cost. Therefore, in this study, the method and process of manufacturing free-formed EPS form using S-LOM-based 3D printing technology were suggested. Furthermore, through the mock-up test, a comparative analysis of the manufacturing time and precision with CNC milling technology was conducted. The results show that S-LOM-based 3D printing technology has reduced manufacturing time about 57.4% compared to CNC milling technology during the free-formed EPS form manufacturing process. In addition, compared to the design drawings, the maximum error value was 20.5mm, proving the applicability of S-LOM-based 3D printing technology. The results of this study are expected to contribute to the improvement of S-LOM method and the activation of S-LOM method by verifying the applicability of S-LOM-based 3D printing technology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.490-496
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• 2017

This study targeted college students to determine the moderating effect of immersion in the relationship among stress, satisfaction with life, and satisfaction with college life. To this end, the level of stress, satisfaction with life, satisfaction with college life, and immersion were measured in353 students attending S University. First of all, correlation analysis showed that stress had a negative correlation with immersion, satisfaction with life, and satisfaction with college life and immersion had a positive correlation with satisfaction with life and satisfaction with college life. Hierarchical regression analysis was conducted to determine the moderating effects of immersion in the relationship among stress, satisfaction with life, and satisfaction with college life. The results showed that immersion had a moderating effect on the relationship between stress and satisfaction with life, while immersion did not have a mitigating effect on the relationship between stress and satisfaction with college life. Based on these findings, this paper suggests raising the ability of immersion as a measure of intervention in handling the stress of college students and discusses the significance and limitations of this study.

• Korean Journal of Environment and Ecology
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• v.11 no.4
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• pp.506-522
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• 1998

Visitors to Naesorak in Soraksan National Park were surveyed from July to December. During this time, 452 visitors were contacted. Of those individuals, 57.08% were males, 30.97% of respondents reported that they had gone beyond highschool, and almost one-half(49.12%) had gone as for as college, 40.93% were 10\cdot 20 years of age. The purpose of this is to suggest objective basic data for the use development and conservation management of the national park through the quantitative analysis of the visual quality included in the physical environment of the Naesorak in Soraksan National Park, for this, spatial images strusture of physical elements have been analyzed by factor analysis algorithm and degree of visual quality have been measured mainly by questionnaries. Result of this thesis can be summarized as follows. Factors covering the spatial image of the Naesorak in Soraksan National Park landscape have been found to be the overall spatial, potentiality, synthetic evaluation, physical and natural quality factors. As for the factors determining the degree of visual quality of clear of valley, peculiarity of configuration, natural of trail, harmony of suitable artificial planting and temple.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.2 no.1
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• pp.160-175
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• 1991

The purpose of this study is to investigate the parental marital relationships and the parent-child relationships of child psychiatric parents and its control group. This study was carried out two questionnaire instruments ; The marital satisfaction inventory(MSI) and the dyadic adjustment scale(DAS). The subjects are parents of the child psychiatric patients. A matched control group and parents of child psychiatric parents in Seoul area which were collected from July 1987 to September 1987, and classified into five subgroups : 1 Psychiatric disorder 2) Neurotic disorder 3) Tic disorder 4) Autistic disorder 5) Mental retardation. The results are as following ; 1) M.S.I scale scores of parents of patients group are lower than that of control group. 2) D.A.S scale score of parents of patients group is significantly lower than that of the control group(P<0.01). 3) The global distress scale(GDS) of the M.S.I. was most positively correlated with affective communication(AFC) and problem-sloving communication(PSC). 4) Female shoed more modern concept of role identification than male but tend to have heavier role assignment especially in child rearing practices which could be characterized by maternal domination. 5) Affective communication and sexual relationship between married couple and child rearing practices are influenced by their own family history of distress. 6) The marital global distress scale(GDS) score was highest in the parents of psychosis, the next in the parents of neurosis, autism, mental retardation, and tic disorder in descending order of severity. 7) The dyadic maladjustment score was highest in the parents of psychosis, the next in the parents of neurosis, tic, autism and mental retardation in descending order of severity. 8) Conflict in child rearing and parenting problems were particularly prominent in parents of the tic patients, and their marital relationship was not significantly disturbed. The above finding suggested that couple adjustment and marital dissatisfaction were closely related with child rearing problems and the children's disorder. So marital dissatisfaction and marital maladjustment seem to play a significant role in the genesis of psychosis and neurosis not much in autism and mental retardation.

• Journal of Korea Technology Innovation Society
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• v.13 no.1
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• pp.124-139
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• 2010

This study analyzes determinants of innovation in Korea manufacturing industries from 2005 to 2007. In order to do this, we use raw data from 'Korea Innovation Survey 2008: Manufacturing Sector' conducted by STEPI, and also collect financial statement data from Korea Investors Service. As an analytical method for the empirical test, we utilize Probit model. Empirical results show that firm size and market concentration have positive relationship with firm's innovation activities. These support the ‘Schumpeterian hypothesis’. This would be the most distinguished feature of this study compared to previous literatures.Our study also shows that R&D personnel ratio, R&D intensity, and advertising intensity have positive effects on firms' innovation. Thus, we can say that R&D activities and consumer orientation are the main determinants of innovation. However, profit ratio and growth rate do not have any statistically significant effect on firms' innovation.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.49-59
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• 2012

Although 3D stereoscopic movies had been paid attention to a few times since the 1900's, the interest had not been last. Most researchers pointed out the reason came from human factors because the early in the 3D technology growth had to develop technological possibility to realize 3D videos and ignore the importance viewers' perspective. In the 2D video research, many studies have explored the factors which make people got immersed or involved and felt visual fatigue, but they have not been the main issues in the 3D research until now. The present research believes human factor issue is one of the most important parts to accelerate 3D industry and thus, we try to make reliable and valid assessments to evaluate 3D video which are perceived characteristics, impression, and presence.