• 전기학회논문지P
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• 제62권4호
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• pp.198-203
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• 2013

There are conditions that can be unbalanced three phase currents in a large generator by untransposed lines, unbalanced loads, unsymmetrical faults, and open phases. The unbalanced conditions can producing negative sequence components of current that induce two times frequence current in the surface of the rotor, the retaining rings, the slot wedges in the field windings. These rotor currents make the rotor rapidly overheat, so the rotor can cause substantial damage in a very short time. This paper presents the digital negative sequence relay algorithm for unbalanced protection in a generator. The proposed algorithm was tested by using collected current signals on PSCAD/EMTDC considering a hydro turbine based generator control system. It can be seen that the proposed relaying by negative sequence current is useful for detection of unbalanced state of large generator.

• 한국조명전기설비학회지:조명전기설비
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• 제10권5호
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• pp.66-74
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• 1996

본 연구는 자계내에서 직류 차단설비의 아크소호 현상을 규명하기 위하여 침대 평판 전극에 부극성 직류 고전압 인가시 아크전압 및 전류 그리고 이들 파형특성을 자계세기의 변화에 따라 연구 검토하였다. 본 연구에서 얻은 중요한 결론은 다음과 같다. 자계가 인가되지 않았을 때는 아크동특성이 나타나지 않고 아크전압의 감소와 아트전류의 증가가 순간적으로 이루어진 후, 일정하게 유지되었을 뿐만아니라 전류 파형으로부터 아크방전이 연속적으로 발생됨을 알수 있었다. 자계가 인가되면 아크동특성이 나타난후, 서서히 아크전압이 감소되고 증가되고 아크전류는 감소되었다. 그리고 전류파형으로부터 아크방전은 단속적으로 됨에 따라 전류영점이 나타남을 알 수 있었고, 전류영점이 나타나는 주기와 아크방전의 단속 주기가 일치하였으며 자계가 증가될수록 주기도 증가되었다.

• 한국해양공학회지
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• 제20권3호
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• pp.1-6
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• 2006

Modulation theory describes propagation of surface waves with deep wave number and frequency modulation. Locally spectrally narrow wave packet can have accumulated large scale frequency shift of carrier wave during propagation. Some important nonlinear modulation effects, such as negative frequencies, phase kinks, crest pairing, etc., often observed experimentally at long fetch propagation of finite amplitude surface wave trains, are reproduced by the proposed theory. The presented model permits also to analyze the appropriately short surface wave packets and modulation periods. Solutions show the wave phase kinks to arise on areas' of relatively small free surface displacement in complete accordance with the experiments.

• 한국의류산업학회지
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• 제18권5호
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• pp.625-636
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• 2016

The purposes of this study were to investigate the effects of social appearance anxiety, negative body image, appearance importance on appearance management behavior and cosmetic surgery intention. For data collection, a questionnaire was administrated to 428 female college students in Gwangju City, Korea. The results were summarized as follows. To analysis the data, the SPSS 20.0 was used, and frequence analysis, descriptive statistical analysis, reliability analysis, regression analysis, F-test were conducted. The results were summarized as follows. First, social appearance anxiety turned out to have significant positive effect on appearance management behavior and cosmetic surgery intention. Second, negative body image had positive effect on appearance management behavior and cosmetic surgery intention. Third, appearance importance turned out to have significant effect on appearance management behavior and cosmetic surgery intention. The results of this study above suggest that it would be necessary to seek for measures to reduce individual's appearance anxiety, negative body image, and appearance importance. Especially, People should get the realization of the beautiful on the inside that includes personality is more important than having external beauty. And, it is considered that the requirements of the social effort and education through a school and a media as well as a family for reducing the individual's appearance anxiety, negative body image, and the serious consideration of the appearance as rejecting the discrimination based on appearance.

• 한국치위생학회지
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• 제7권3호
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• pp.231-245
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• 2007

This study aims to discuss plans to improve the satisfaction level of dental services by understanding characters of beliefs about dental manpower and analyzing its related factors. Data were collected by structured questionnaire whose subjects consist of 1607 persons from 13 years old to 69 years old, who have ever experienced dental institution. Both univariate and biovariate analyses were employed to analyze level of dentist and dental hygienist's beliefs and its related factors and the results gained from the surveys and search are as follows. 1. Among the questions to measure dentist's beliefs, 'Respect for patients' was evaluated as the best, and the lowest items were 'not-hopeful explanation about prognosis of dental treatment', 'satisfactory explanation' and 'whether treatments are stopped by pains or not'. In addition, among questions to measure dental hygienist's beliefs, 'kindly welcome' and 'detailed explanations about medical directions' are the items evaluated as the best and 'notice of waiting time' marked the lowest evaluation. 2. The factors related to beliefs about dentists were age, ache experiences, dental fear, self-reported dental health status, frequence and primary purposes of the visits dental institutions, elapsed time from recently visited, present of favorite dental clinic to visit regularly. 3. The factors related to beliefs about dental hygienists were age, education, occupation, ache experiences, frequence and primary purposes of the visits dental institutions, periodic check of teeth, present of favorite dental clinic to visit regularly. 4. Direct painful, painful treatment experience under insufficient local anesthetic, indirect painful experience and dental fear were positively correlated. And the relationships were positive between ache experiences, dental fear and self-reported dental health status, but relationships were negative between ache experiences, dental fear and dentist! dental hygienist's beliefs.

• 가정과삶의질연구
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• 제8권2호
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• pp.15-30
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• 1990

The purpose of this study are 1) to offer the basic data for consumer education by examining and analyzing housewife's Life Style. 2) to make the housewife lead for Life Style better and more resonable. Questionnaires were sent to 623 housewives in Pusan who have elementary , middle and high school students. Frequence, Factor analysis, Cluster analysis, One-way Anova, X 2-test were used to take statistics. The results were as follows. 1) Housewife's Life Style in independent house area were ' the economical seeking pattern' which takes up th high proportions, next 'the practical reserved seeking pattern' ,'the tradition and reservational fashion seeking pattern', and 'the negative neverlessness pattern' On the other hand, the Life-Style in apartment area were' the rapid purpose seeking pattern', next ' the economical seeking pattern', the fashion and pleasure seeking pattern' and 'the tradition and reservational fashion seeking pattern'. 2) By surveying the relationships the housewife's Life Style and the demographics, first, there was a difference in housewife's Life Style of the independent house area by the level of education, monthly mean income and husbands occupation. 3) Finally, as I studied th characterization of which they possessed thing, it usually appeared the characteristic possession by types.

• 한국ITS학회 논문지
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• 제18권3호
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• pp.1-13
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• 2019

이용객 감소, 고령화 등으로 어려움을 겪고 있는 농어촌버스의 대체수단으로 시범운영에 있는 수요응답형교통 콜버스에 대해 연구한다. 운영전 농어촌버스 대비 콜버스의 선호분석을 위해 로그선형모형을 구축하고 운영중의 콜버스 만족도를 조사하여 영향을 주는 요인을 순위회귀모형으로 실증 분석하였다. 연구결과로 문전서비스의 편리함으로 고령층과 이동수단에서 제약이 큰 것으로 예상되는 여성이 콜버스를 선호할 가능성이 높았다. 이동수단이 없거나 외출빈도가 낮은 경우에도 콜버스를 선호한다. 종속변수인 콜버스 만족도의 경중에 따른 순위분석에서 농어촌버스 선호자의 경우 연령, 가족수, 정류장거리, 외출횟수, 귀가시간에서 통계적 중요성을 보였고. 콜버스 선호자의 경우 성별, 이동수단, 정류장까지 거리, 버스만족도, 외출빈도, 출발시간, 귀가시간에서 통계적 중요성을 보였다. 전반적으로 운행전 콜버스에 긍정적 생각을 가진 대상자들이 콜버스 운행후에도 여전히 높은 만족도를 보였다.

• Journal of Periodontal and Implant Science
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• 제33권2호
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• pp.159-166
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• 2003

The purpose of this study was to investigate and compare the frequence of 4 periodontal pathogens in the supra- and subgingival plaque in periodontally healthy subjects. Twenty adult individuals aged 22 to 28 years (mean age 23.65 years) participated in this study. All subjects had no pocket sites more than 3 mm deep, and the sites selected for sampling were all negative for bleeding. After drying and isolation of the sites with cotton rolls, supragingival plaque was sampled using sterile periodontal curette. Each plaque sample was placed in individual tubes containing 500 ml of 1X PBS. After removal of the supragingival sample and any remaining supragingival plaque, subgingival plaque samples were taken from the same sites using sterile curette and placed in similar individual tubes. Identification of 4 putative periodontal pathogens from the samples was performed by polymerase chain reaction based on 16S rDNA. Chi-square test was employed to identify significant explanatory variables for the presence of the 4 periodontal pathogens. The data show that Actinobacillus actinmycetemcomitans, Porphyromonanas gingivalis, Bacteroides forsythus, and Fusobacterium nucleatum occurred in 16.9%, 14.4%, 52.5%, and 80.6%, respectively. No significant differences were noted in the periodontal pathogens between supra- and subgingival plaques according to the kind of teeth. However, the incisors were at higher risk for harboring F. nucleatum (p <0.05). Conclusion: These results reveal that anaerobic periodontal pathogens can be detected in supragingival plaques. Supragingival plaque may function as a reservoir of peri-odotopathogens.