• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.117-119
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• 2005

Voltage Flicker는 다른 전력품질 요소들과는 달리, 전압의 흔들림이 사람의 눈과 뇌에 미치는 영향을 고려한 지수이다. IEC 61000-4-15에서는 이러한 플리커의 평가 알고리즘을 제시하고 있으며, 제한치를 $Pst{\leq}1$, $Plt{\leq}0.65$로 정의하고 있다. 이 제한치는 다양한 비선형 부하들의 경우에도 만족시켜야 하며, 계통의 설계 시 미리 고려를 할 필요성이 있다. 본 논문에서는 Fortran을 이용하여 IEC61000-4-15의 플리커미터 알고리즘을 구현하고 이를 PSCAD/EMTDC의 Module로 적용시켜, 시험 계통이 플리커 제한치를 만족시키는가에 대한 테스트가 가능하도록 하였다.

• 전기의세계
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• v.10
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• pp.55-61
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• 1963

본 논문에서 취급한 제동권선이 없는 철극선의 3상단락현상을 해명하는데 있어 우선 임의력율의 전류를 횡축분과 직축분으로 분리해서 취급하는 소위 Blonde의 2반작용법(two reaction method)를 썼고, 각종 Reactance를 표시하는데는 편리한 단위법(perunit notation)을 사용했으며, 전기자의 1상저항은 각종 Reactance ( $X_{x}$, $X_{q}$ )의 어느것 보담도 극소치임으로 실제계산에는 무시했으나 과도전류의 변화를 좌우하는 감쇠정수[decrement factor)에는 큰 영향을 준다는 것이 규명되었다. 해석결과로서 3상단락전류의 초기치는 특수치보다 훨씬 큰 이유로서 단락전류가 계자자속을 약하게 만들어 그 반동으로 계자회로에 일정자속을 유지하기 위하여 부문적으로 개자전류가 증대함을 알게되었고, 단락전류의 직축분과 횡축분의 구성분이 규명검토되었고, 발전기의 돌발단락저류는 일반적으로 직류분, 기본파교류분 및 제2조파등을 포함하나 그 전부가 시정수의 역수인 감쇠정수에 지배되어서 지수함수곡선에 따라 감쇠되어 결국에는 지속단락전류에 귀착한다는 사실과 3상단락은 평형단락사고임으로 영상전류는 영이며 각상과도전류의 위상차가 120.deg.라는 것엔 변함이 없다는 것과 끝으로 철극기를 정격속도로 운전해 놓고 이것을 여자해서 무부하전압을 수기시켜 그의 3상전단자를 돌연 단락해서 그의 과도전류의 파형을 Oscillograph로 촬영하면 본론에서 해석한 결과식의 그것과 일치하게 됨을 알 수 있을 것이다.것이다.

• Proceedings of the Korea Society for Simulation Conference
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• 1996.05a
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• pp.9-9
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• 1996

광대역 종합정보 통신망의 핵심요소라 할 수 있는 ATM 스위치의 성능척도 중 가장 중요하게 다루어지고 있는 것은 셀 손실확률과 셀 전달지연시간이다. 이 중에서도 샐 손실확률기 추정에 대한 연구가 활발히 진행되고 있는데, ATM 스위치는 손실에 민감한 트래픽까지도 제대로 다루기 위하여 정도까지의 샐 손실확률을 보장할 수 있어야 한다. 이와같은 희소사건(rare event)의 확률 추정에 있어 원하는 정도의 precision을 가능한한 적은비용으로 얻어내기 위한 분산축소기법은 필수적이라 할 수 있다. Homogeneous 입력원을 갖는 ATM 스위치의 셀 손실확률 추정에 관련된 이전의 연구결과는 시뮬레이션과 분석적기법을 혼합시켜 얻어지는 새로운 개념의 추정치, 즉 hybrid 시뮬레이션 추정치의 도입을 통하여 상당한 정도의 분산축소 효과를 거둘 수 있음을 나타내주고 있다. 본 연구는 이에 대한 확장으로, 각각의 도착 프로세스가 서로 다른heterogeneous 입력원을 갖는 ATM 스위치의 셀 손실화률 추정에 적용될 수 있는 hybrid 시뮬레이션 기법을 개발하고자 한다. 사용된 모델은 이산시간대기모델()로 각입력원의 도착 프로세스는 Interrupted Bernoulli Process로 가정하였으며, 분석적 기법의 적용을 위한 입력원 통합(aggregation) 알고리듬과 실제 시뮬레이션 방법 등을 제시하였다. 또한 제시된 기법의 성능은 기존의 일반적인 시뮬레이션 추정치를 이용하여 얻어진 결과와의 비교를 통하여 분석되었다.

• Journal of the Korea Computer Industry Society
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• v.2 no.7
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• pp.967-974
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• 2001

This paper aims at deriving an equivalent finite dimensional discrete-time system for $H{\infty}$ type problem for sampled-data control systems. A widely used approach is based on the lifting technique, but it needs somewhat complicate computation. Instead, this paper derives an equivalent finite-dimensional discrete-time system directly from a description of the sampled-data system which is achieved via a closed-loop expression of the worst-case intersample disturbance.

• Journal of Korean society of Dental Hygiene
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• v.6 no.1
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• pp.13-23
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• 2006

A number of studies are beginning to show that oral disorders can have a significant impact on the functional, social and psychological well-being of adult. The aim of this study was to measure, the Oral Health Impact Profile(OHIP), which has recently been tested in studies of oral health of adult aged 55 years and older. The sample consisted of 380 adults The measure proved to be reliable and valid, while data collected using this measure indicated that oral conditions have negative impact on the daily, this impact was particularly marked among both edentulous and dentulous individuals who did not make regular visits for dental care. The relationship between the OHIP 7 demention compared with the group based on their dental state and age group was statistically Signification(pE0.01) people with denture were more likly to report having many problems in all seven dimention corvered by OHIP scale than those with natural teeth only These results indicated that the OHIP has a negative impact on the daily lives of a substantial proportions of older people. This impact was particularly noticeable among the edentulous and denture wearers.

• Journal of Korean society of Dental Hygiene
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• v.14 no.5
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• pp.757-764
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• 2014

Objectives : The purpose of this study was to investigate the oral health impact profile (OHIP) in the industrial accident injury patients, and the effect of subjective perception and attitude of oral health on the oral health-related quality of life in industrial injury patients. Methods : A self-reported questionnaire was filled out by 496 industrial accident injury patients from October 29 to November 30, 2013. Data were analyzed using SPSS ver 20.0 program for chi-square test, t-test, ANOVA, Scheffe test, and Pearson's correlation coefficient. Results : The OHIP-14 was higher oral health-related quality of life in young people, women, highly educated persons, and those having high income and frequent scaling service. The subjective perception and attitude of oral health was closely correlated to the OHIP-14. The factors influencing on the oral health-related quality of life were the subjective perception and attitude toward oral health. Conclusions : It is necessary to emphasize the oral health promotion program for industrial injury patients. The government should pay more attention to the policy for the improvement of the oral health of industrial accident injury patients in the future.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.5-17
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• 2000

The physical and mechanical properties of the sedimentary rocks deposited in Taegu and Kyongbuk region have been measured in the laboratory and at the field. Four kinds of rocks such as the shale, the mudstone, the siltstone and the sandstone were the object of this study. In sedimentary rock joint, bedding made it impossible to extract cores for uniaxial compressive test. Some correlations between the uniaxial compressive strength and the other characteristic values such as Point load index, Schmidt hammer rebound, Brazilian strength, P-wave velocity and Absorption ratio are made. The chemical and mineral compositions are also investigated by the XRF and XRD analysis. In addition, the weathering grade of rocks are classified by the quantitative indices of Point load index, Schmidt hammer rebound and Absorption ratio.

• Journal of Korean society of Dental Hygiene
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• v.10 no.6
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• pp.1015-1024
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• 2010

Objectives : This study was to investigate the level of health risk behavior, athletes stress, quality of life(WHOQOL-BREF) and oral health related quality of life(OHIP-14) and the clinical factors influencing quality of life in athletes Methods : Data were obtained from a cross-sectional survey of 202 university athletes. Data was obtained by means of questionnaire from October 11 to October 15, 2010. Health risk behaviors(Q-F index and smoking), athletes stress, WHOQOL-BREF and OHIP-14 were measured. The data was analysed with t-test, one-way ANOVA, Pearson correlation coefficient and multiple regression using the SPSS program. Results : The prevalence of alcohol drinking, smoking were 84.2% and 37.9%, respectively. Alcohol drinking and cigarette consumption were not related to quality of life though there were the negative correlation between athletes stress and quality of life. Powerful predictors of quality of life were athletes stress, OHIP-14 and perceived health for athletes. Conclusions : Based on the findings, quality of life has a significantly impact on athletes stress, OHIP-14 and perceived health. These results suggest that the implementation of health promotion program should be considered which was decreased athletes stress and was increased level of oral health and perceived health in athletes.

• Journal of Korean society of Dental Hygiene
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• v.9 no.2
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• pp.221-228
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• 2009

The purpose of this study was to evaluate the impact of oral health impact profile in two urban area The respondents enrolled in this study were elderly people aged 65years from Gwang-ju city, Sunchon city. A total of 371 participants(Gwang-ju city 161, Sunchon city 210) analyzed. The contents of the research were social demographic characteristics, self perceived need for dental care, attributes related to denture, dental visiting pattern, the perceptions regarding dental health condition, and OHIP-14. 1. In the comparison Two urban area, the perceptions regarding dental health condition, self perceived need for dental care, dental visiting pattern was statistically significant difference(p<0.05). 2. Among the 7 OHIP-14 subscales, the mean scores of physical disability were significantly higher in two urban area(p<0.05). 3. The Social demographic characteristics, OHIP-14 represented a statistically significant difference related to gender, age and denture use(p<0.05). Through this research, Both Gwang-ju city and Sunchon city was found that elderly people was more negative impact of physical disability on oral health related quality of life. Therefore need to oral health program for improving oral health in the elderly people.

• Journal of Korean society of Dental Hygiene
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• v.15 no.6
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• pp.991-997
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• 2015

Objectives: The purpose of the study is to investigate the relationship between body mass index(BMI) and periodontal disease in Korean adult from the data of the fifth Korea National Health and Nutrition Examination Survey(KNHANES). Methods: The subjects were 3,309 adults from 25 ro 45 years old in the fifth KNHANES. The subjects were divided into three BMI categories: normal weight 1,549(BMI ${\leq}22.9kg/m^2$), overweight 792(BMI $23.0-25.0kg/m^2$) and obesity 968(BMI ${\geq}25.0kg/m^2$). Periodontal disease was assessed by community periodontal index(CPI) and periodontitis was defined as ${\geq}$ code 3. Results: Increased BMI adults had no significantly higher prevalence of periodontitis than those having normal body weight after adjusting for variables; the odds ratio(OR) was 1.06 in overweight and 1.23 in obesity. BMI and periodontitis had no significant relation to increased age, but the age increase tended to have high odds ratio. Women had a higher OR than men. Conclusions: Through this study, it is necessary to analyze the relationship between the obesity index and periodontitis in the further study.