STATCOM을 활용한 FIDVR 완화 방안에 대한 연구

이윤환(Yunhwan Lee),정승민(Seungmin Jung) 대한전기학회 2018 전기학회논문지 P Vol.67 No.4

In this paper, we studied the control strategy of applying STATCOM(static synchronous compensator) to mitigate the FIDVR(fault induced delayed voltage recovery) phenomenon. The proportion of motor loads is gradually increasing which might affect power system stability. Excessive reactive power consumption by the stall of the motor loads causes FIDVR phenomenon. In addition, the low inertia of the small HVAC(heating, ventilation and air conditioner) unit will not separate itself in the event of a contingency, causing system instability. For this reason, we have developed a control strategy that utilizes STATCOM efficiently through static and dynamic analysis. Case studies on a Korean power system have validated the performance of the proposed scheme under severe contingency scenarios. The results have verified that the proposed strategy can effectively mitigate FIDVR and improve the stability and reliability of the system.

전압 변동률을 고려한 수도권 전압 안정화 다단계 부하차단 적용 방안

이윤환(Yunhwan Lee),김태균(Taegyun Kim),김지훈(Jihun Kim),이병준(Byongjun Lee),강부일(Bu-il Kang),조종만(Jongman Cho) 대한전기학회 2009 전기학회논문지 Vol.58 No.12

High technique growth of modern times and high industrial facility in consequence of buildings demand for electric power of an extensive scale with stability supply and maintenance of high quality. But, power system always have risk of network contingency. When power system break out disturbance, it circumstantially happen like uncontrolled loss of load developing from of cascading. Severely which would be raised wide area blackout, plan to prevent, which make stability through a little of load shedding and multi-level UnderVoltageLoadShdding should work. This paper presents target, sensitivity of bus voltage have choose appropriating load shedding location and load shedding decision making logic with considering rate of change of voltage have studied multi-level under voltage load shedding scheme. Calculation of rate of change of voltage applied method of least square. As a result, we are studied an dynamic analysis of 2008 summer peak data. We have been known that network analysis is a little development and developing UnderVoltageLoadShedding scheme.

지역사회 노인에서 불안과 뇌졸중 경고증상의 관계

이수현(Su Hyun Lee),고상현(Sang Hyun Koh),이윤환(Yunhwan Lee),백종환(Joung Hwan Back),정영기(Young Ki Chung),김현정(Hyun Chung Kim),홍창형(Chang Hyung Hong) 대한노인정신의학회 2011 노인정신의학 Vol.15 No.1

Objectives:We aimed to investigate the relationship between anxiety and stroke warning signs in the elderly. Methods:Data obtained from 1,078 subjects (256 men and 822 women) aged above 65 years was analyzed from Suwon Project, which was a cohort comprising of nonrandom convenience samples. All the subjects completed the study questionnaire including their demographic characteristics, history of current and past illnesses, drug history, Korean version-Mini Mental State Examination (K-MMSE), SGDS-K (Korean version of the Geriatric Depression Scale-Short Form), BAI (Beck Anxiety Inventory). Stroke warning signs were defined as 5 stroke warning signs consistent with the American heart association public health message Results:There was significant relationship of anxiety and the number of stroke warning signs after adjusting age, sex, educational level and depression (β=2.145, p〈0.0001). On analysis of covariance, the interaction of the number of experienced stroke warning signs with sex on anxiety was observed after adjusting for the age, educational level, K-MMSE, and SGDS-K (p=0.011). Conclusion:These results suggest that there was significant relationship of anxiety and stroke the elderly.

후두양성점막질환의 유병률과 인구사회학 및 건강 관련 요인

변해원(Haewon Byeon),이윤환(Yunhwan Lee) 한국언어청각임상학회 2010 Communication Sciences and Disorders Vol.15 No.4

배경 및 목적: 한국인의 음성질환 유병률과 위험요인의 연구는 미흡한 실정이다. 이 연구에서는 제4기 2차년도(2008) 국민건강영양조사의 이비인후과 검진자료를 사용하여 후두양성점막 질환의 유병률 자료를 제시하고, 관련 요인을 분석하고자 하였다. 방법: 건강설문조사와 이비인후검사 설문 및 검진, 후두내시경 검사를 완료한 전국의 성인 3,141(남: 1,313, 여: 1,828)명을 대상으로 유병률을 조사하였다. 후두양성점막질환의 관련 요인을 파악하기 위해서 단변량 및 다변량 로지스틱 회귀분석을 사용하여 교차비(Odds Ratio: OR, 이하 OR)와 95% 신뢰구간을 제시하였다. 결과: 19세 이상 성인의 후두양성점막질환 유병률은 2.5%로, 50대와 60대에서, 여성보다 남성에서 유병률이 상대적으로 더 높았다. 단변량 분석 결과 후두양성점막질환관련 요인은 단순노무직, 주관적 음성문제 인지, 현재흡연, 음주빈도였다. 직업이 없는 사람에 비해 단순노무직인 사람은 후두양성점막질환에 걸릴 가능성이 60% 더 낮았다(OR = 0.40, 95% CI: 0.21∼0.75). 반면에 후두양성질환 관련성은 음성문제를 느끼지 않는 사람에 비해서 3주 이내에 스스로 음성문제를 인식한 경우는 4.4배(OR = 4.44, 95% CI: 1.85∼10.66), 3주 이상 음성문제를 인식한 경우는 9배(OR = 9.00, 95% CI: 5.34∼15.18), 비흡연자에 비해서 현재 흡연자는 1.8배(OR = 1.82, 95% CI: 1.13∼2.93), 주1회 이하 음주자에 비해 주 4회 이상 음주자는 2.1배(OR = 2.08, 95% CI: 1.07∼4.01) 더 높았다. 모든 변수(연령, 성, 교육수준, 직업, 주관적음성문제인지, 비만유병, 흡연여부, 음주빈도, 폭음)를 보정한 후에도 단순노무직, 주관적 음성문제 인지, 음주빈도는 후두양성점막질환과 독립적인 관련이 있었다. 결론: 이 결과는 후두양성점막질환의 예방 및 재발 방지를 위한 구체적인 근거자료로 활용될 수 있을 것이다. Background & Objectives: Studies on the prevalence and risk factors of voice disorders in Korean adults are rare. The purpose of the present study was to analyze the prevalence of benign laryngeal lesions and to identify variables associated with increased risk of benign laryngeal lesions. Methods: Data were taken from the 4th Korea National Health and Nutritional Examination Survey (2008). Subjects consisted of 3,141 people aged 19 years and older. Potential factors associated with benign laryngeal lesions were analyzed using chi-square tests and multiple logistic regression. Results: The prevalence of benign laryngeal lesions was 2.5% in the adult population. In the logistic regression analysis, being a manual worker was inversely associated with benign laryngeal lesions (OR=0.40, 95% CI: 0.21, 0.75). Subjective voice problems in the past 3 weeks (OR=4.44 95% CI: 1.85-10.66) and for more than 3 weeks (OR=9.00, 95% CI: 5.34-15.18), currently smoking (OR=1.82, 95% CI: 1.13-2.93), and frequent alcohol consumption (OR=2.08, 95% CI:1.07-4.01) were significantly associated with benign laryngeal lesions. Adjusting for covariates, being a manual worker, having subjective voice problems, and frequent alcohol consumption were independently associated with benign laryngeal lesions. Discussion & Conclusion: Benign laryngeal lesions are prevalent among adults. The findings of associated factors suggest potential ways of targeting counseling and prevention efforts to control benign laryngeal lesions.

노인의 사회활동이 신체기능에 미치는 영향

박경혜(Park, Kyunghye),이윤환(Lee, Yunhwan) 한국노년학회 2006 한국노년학 Vol.26 No.2

노인의 사회활동과 신체기능과의 관계에 대한 최근 연구들은 두 요인 사이에 강한 연관성을 제시하고 있다. 그러나 노인이 사회활동을 많이 하기 때문에 신체기능이 좋은 것인지, 신체기능이 좋기 때문에 사회활동에 많이 참여하는 것인지, 그 연관성의 방향에 대한 증거는 부족한 실정이다. 이에 본 연구는 노인의 사회활동과 신체기능의 두 요인 젓 어떤 요인이 선행요인인지를 밝히고자 하였다. 이를 위해 2001~2003년에 걸쳐 수행된 수원시 종적 노화연구의 1, 3차년도 자료를 이용하여 65세 이상 재가노인 537명의 사회활동(친척ㆍ친구ㆍ이웃과 접촉빈도, 종교 및 문화활동) 점수와 신체기능(PF 척도) 점수간의 관계를 살펴보았다. 먼저 시차적 교차패널기법(Cross-lagged panel technique)을 통해 1차년도 사회활동-3차년도 신체기능간의 상관과 1차 년도 신체기능-3차년도 사회활동간의 상관관계를 비교함으로써 선행요인을 알아보았다. 다음으로 각 변인들의 독립적인 효과를 알아보기 위하여 혼란변수들을 통제한 상태에서 각각 선형회귀분석을 실시하였다. 시차적 교차패널분석 결과, 1차년도 사회활동-3차년도 신체기능의 상관계수가 1차년도 신체기능-3차년도 사회활동의 상관계수보다 더 높았다. 회귀분석 결과 사회활동이 신체기능에 미치는 효과는 통계적으로 유의하였고, 그 효과는 인구사회학적 변인들(연령, 성, 교육수준, 수입)과 건강관련 변인들(주관적 건강인식, 인지건강, 만성질병의 개수, 운동빈도)을 통제한 후에도 유의하였다. 한편 대응되는 관계인 신체기능이 사회활동에 미치는 효과는 통계적으로 유의하였으나, 인구사회학적 변인들과 건강관련 변인들을 통제한 후에는 그 효과가 유의하지 않았다. 이 결과를 통해서 사회활동이 신체기능의 원인으로 작용하며, 노인의 사회활동이 많을수록 신체기능이 양호하다는 사실을 추론할 수 있다. 노인의 사회활동과 신체기능간 인과관계를 파악한 결과는 노인의 사회활동과 신체기능의 관계에 대해서 종전보다 깊이있는 이해를 가능하게 하며, 노인관련 임상분야나 정책부문에 있어서 노년기 건강상태 증진을 위해서도 노년기 사회활동 프로그램의 활성화가 필요함을 시사해준다. This study examined the temporal relationship between social activities and physical functioning in older adults. Two waves of 2001 and 2003 data, from the SLAS (Suwon Longitudinal Aging Study), of 537 people aged 65 years or over, were analyzed. Social activities were measured by using items related to the frequency of contact with relatives, friends, and neighbors, and religious and cultural activities. Physical functioning(PF) consisted of measures of mobility, activities of daily living(ADLs), and instrumental activities of daily living(IADLs). We examined the direction of the association by using cross-lagged panel technique to test causality through longitudinal study as a substitute for a controlled experiment. Then hierarchical regression models were fitted to examine if social activities affect physical functioning independently, or vice versa, adjusting for sociodemographic and health-related covariates. Cross-lagged panel design showed that the correlation between social activities ratings at Wave 1(2001) and PF 2 years later was higher than the correlation between PF at Wave 1 and social activities ratings 2 years later. After adjusting for sociodemographic and health-related covariates, the effect of social activities on PF remained significant, but not for PF on social activities. Results suggest that social activities contribute to older person's physical functioning. Further work, however, is needed to confirm the potential causal association by controlled experiments.

노인에서 주관적으로 지각한 신체 및 정신건강수준이 인지감퇴에 미치는 영향

권윤영(Yunyoung Kwon),손상준(Sang Joon Son),이윤환(Yunhwan Lee),백종환(Jong Hwan Back),노재성(Jai Sung Noh),고상현(Sang Hyun Koh),김현정(Hyun Chung Kim),김진주(Jinju Kim),박미애(Mi Ae Park),홍창형(Chang Hyung Hong) 대한노인정신의학회 2013 노인정신의학 Vol.17 No.1

Objectives:The aim of this study was to describe subjective physical and mental health assessed by the single item self-rated physical health (SRPH), and self-rated mental health (SRMH) had influence on the cognitive decline in community-dwelling elderly. Methods:This study was based on the Suwon Project, a cohort comprising of non-random convenience samples of ethnic Koreans aged 60 years and above. 1,356 individuals were assessed at 2 time points 2 years apart for questionnaire which included demographic characteristics, medical history, Korean Mini-Mental State Examination (K-MMSE), Korean version of Geriatric Depression Scale (SGDS-K), SRPH, and SRMH. Multiple logistic regression was used to assess K-MMSE score change from the SRPH, and SRMH. Results:At baseline, both SRPH (β=0.18, p<0.01) and SRMH (β=0.19, p<0.01) score positively associated with the K-MMSE score. At follow-up, subjects with baseline lower SRMH score had significantly greater decline in K-MMSE score (β=0.09, p=0.007). However, baseline SRPH score showed no effect to follow up K-MMSE score before and after adjusting age, sex, education, number of chronic disease, SGDS-K, and baseline K-MMSE score (p=0.89). Conclusion:Brief and easily collected subjective mental health may predict the risk of cognitive decline, but subjective physical health may not.

한국 지역사회 노인의 사회적 활동과 인지기능의 연관성

조우동(Woodong Jo),손상준(Sang Joon Son),이윤환(Yunhwan Lee),백종환(Joung Hwan Back),노재성(Jai Sung Noh),고상현(Sang Hyun Koh),김현정(Hyun Chung Kim),김진주(Jinju Kim),박미애(Mi Ae Park),홍창형(Chang Hyung Hong) 대한노인정신의학회 2012 노인정신의학 Vol.16 No.1

Objectives:Among non-pharmaceutical measures for preventing cognitive impairment, involving in social activities is known to be very effective. We tried to examine the correlation between social activity and cognitive function. Methods:This study was based on the Suwon Project, a cohort comprising of non-random convenience samples of ethnic Koreans aged 60 years and above. All the subjects completed the study questionnaire which included demographic characteristics, current and past history of illnesses, drug history, Korean version of Mini Mental State Examination (K-MMSE), Korean version of Short Form Geriatric Depression Scale, and Beck Anxiety Inventory. We checked the time consumed in each 9 social activities through the checklist. Results:On multiple logistic regression analysis, the total time spent in social activities wasinversely associated with the K-MMSE score after adjusting confounding variables like age, sex, education level, depression, anxiety and vascular risk factor (β= -0.041, p=0.024). On the other hand, correlation was found between K-MMSE score and time spent in participating in religious party (β=0.053, p=0.003) as well as time spent in elder’s university (β=0.040, p=0.025) after adjustingage, sex, education, depression, anxiety and vascular risk factor. Conclusion:Our results suggest that involving in quality social activities might be more effective in improving cognitive function than spending longer total time in any social activity.

발전기손실계수를 활용한 765kV 루트사고의 다년도 계통해석

오승찬(Seungchan Oh),박보현(Bohyun Park),이윤환(Yunhwan Lee),이병준(Byongjun Lee),한상욱(Sangwook Han),권영훈(Kwon Young-Hun) 대한전기학회 2013 대한전기학회 학술대회 논문집 Vol.2013 No.7

시뮬레이션 기반 유지관리계획 평가 기술 개발

조원정(WonJung, Cho),변지환(JiHwan, Byeon),이윤환(YunHwan, Lee),윤성현(SungHyun, Yoon) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.2

지역사회 노인의 인지기능과 정신적 활동의 연관성

여현철(Hyun Chul Yuh),고상현(Sang Hyun Koh),이윤환(Yunhwan Lee),백종환(Joung Hwan Back),임기영(Ki Young Lim),김현정(Hyun Chung Kim),홍창형(Chang Hyung Hong) 대한노인정신의학회 2011 노인정신의학 Vol.15 No.1

Objectives:The purpose of this study was to describe the status of mental activity participation in community-dwelling elderly and to evaluate the association between mental activity and cognitive function after adjustment for depression and anxiety. Methods:This study was based on the Suwon Project, which was a cohort comprising of nonrandom convenience samples of ethnic Koreans aged 60 years and above. All the subjects completed the study questionnaire including their demographic characteristics, current and past illnesses history, drug history, Korean version-Mini Mental State Examination (K-MMSE), Korean version of Short Form Geriatric Depression Scale (SGDS-K), Beck Anxiety Inventory (BAI). We checked how many hours per day are used for each items of 11 mental activities through the checklist. Results:Total time spent in 11 mental activities was 237.4±152.4 minutes per day. On multiple regression analysis, total time spent in 11 mental activities (MA-total), and time spent by watching television and reading book/newspaper showed statistically significant association with K-MMSE score after adjustment with age, sex, education, chronic medical illness, depression and anxiety. Conclusion:Our result suggested that mental activity may be associated with cognitive function in the elderly without cognitive impairment in the community after adjusting age, sex, education, chronic medical illness, depression and anxiety.