• 한국지진공학회논문집
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• 제3권3호
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• pp.33-44
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• 1999

지진의 시간적인 요인, 즉 반복하중효과와 이에 따른 누적소성변위를 고려하기 위하여 에너지 평형에 근거한 해석방법이 개발되었다 본 논문에서는 내진 설계되지 않은 골조 기둥의 파괴유형에 주목하고자 한다. 이를 위하여 기둥의 휨강도저감모델이 제안되는데 파괴유형별로는 콘크리트에의한 파괴 주근의 부착/정착강도 파괴 및 저사이클피로에 의한 주근의 파단등을 고려하였다 에너지에 근거한 모델에 의하여 예측된 응답과 실험결과를 비교하였으며 이론과 실험간의 응답과 파괴유형이 서로 매우 가까움을 확인하였다.

• Journal of Welding and Joining
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• 제32권1호
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• pp.71-78
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• 2014

Although the fatigue design curve of ASME Code has enough margin with respect to alternating stress and cycles, the welding residual stress(WRS) should be included in fatigue analysis. In this paper, WRS distribution in a nozzle with dissimilar metal weldment was obtained by finite element analysis and was added in fatigue analysis. The fatigue analysis was performed by following the ASME Code including thermal and stress analysis applying with postulated 30 transient conditions. The calculated results of a cumulative fatigue usage factors(CUF) were compared for the case of the models with or without WRS effects. The results showed that the CUF at weldment and heat affected zone was affected by the WRS.

• Steel and Composite Structures
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• 제10권4호
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• pp.331-348
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• 2010

Ample research effort has been oriented into developing damage indices with the aim of estimating in a reasonable manner the consequences, in terms of structural damage and deterioration, of severe plastic cycling. Although several studies have been devoted to calibrate damage indices for steel and reinforced concrete members; currently, there is a challenge to study and calibrate the use of such indices for the practical evaluation of complex structures. The aim of this paper is to introduce an energy-based damage index for multi-degree-of-freedom steel buildings that accounts explicitly for the effects of cumulative plastic deformation demands. The model has been developed by complementing the results obtained from experimental testing of steel members with those derived from analytical studies regarding the distribution of plastic demands on several steel frames designed according to the Mexico City Building Code. It is concluded that the approach discussed herein is a promising tool for practical structural evaluation of framed structures subjected to large energy demands.

• Communications for Statistical Applications and Methods
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• 제30권1호
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• pp.1-19
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• 2023

Observational data with missing or incomplete data are common in biomedical research. Multiple imputation is an effective approach to handle missing data with the ability to decrease bias while increasing statistical power and efficiency. In recent years propensity score (PS) matching has been increasingly used in observational studies to estimate treatment effect as it can reduce confounding due to measured baseline covariates. In this paper, we describe in detail approaches to competing risk analysis in the setting of incomplete observational data when using PS matching. First, we used multiple imputation to impute several missing variables simultaneously, then conducted propensity-score matching to match statin-exposed patients with those unexposed. Afterwards, we assessed the effect of statin exposure on the risk of heart failure-related hospitalizations or emergency visits by estimating both relative and absolute effects. Collectively, we provided a general methodological framework to assess treatment effect in incomplete observational data. In addition, we presented a practical approach to produce overall cumulative incidence function (CIF) based on estimates from multiple imputed and PS-matched samples.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.379-379
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• 2020

The influence of drought has increased due to global warming. In addition, forest fires have occurred more frequently due to droughts and resulted in property losses and casualty. In this study, the effects of drought on Goseong-Sokcho Forest Fire in 2019 were analyzed using high-resolution synthetic precipitation data. In order to determine the severity of drought, the average, 20%tile and 80%ile values were calculated using the synthetic precipitation data of the past 30 years and compared with the current climatology. We have investigated the multi-year accumulated precipitation data to determine the persistence of drought. In Goseong-Sokcho forest fire case, the two-year cumulative synthetic precipitation data shows a similar value to the climate, but the three-year cumulative synthetic precipitation data was close to the 20%ile lines of the climate value. It may expose that the shortage of precipitation in 2017 had persisted until 2019, despite abundant precipitation during the summer in 2018. Therefore, Goseong-Sokcho forest fire might be spread more rapidly by drought which has been persisted since 2017.

• Asian-Australasian Journal of Animal Sciences
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• 제22권4호
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• pp.459-464
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• 2009

Data and pedigree information for Lori-Bakhtiari sheep used in this study were 6,239 records of lamb mortality from 246 sires and 1,721 dams, collected from 1989 through 2007 from a Lori-Bakhtiari flock at Shooli station in Shahrekord. The traits investigated were cumulative lamb mortality from birth up to 7 days, up to 14 days, up to 21 days, and up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 months of age. The models included fixed factors that had significant effects and random direct genetic, maternal genetic and maternal permanent environmental effects. Variance components were estimated using the restricted maximum likelihood procedure applying three animal models with and without maternal and common environmental effects. The overall mean of cumulative lamb mortality rate was 22.95% from birth to 1 year of age, while the overall mortality rate up to 3 and from 3 to 6 months of age was 6.14% and 12.76%, respectively. The mortality rate after 6 months of age declined as the lambs grew older. The age of dam had no important effect on lamb mortality. The type of birth was more important during the preweaning period than at later ages, and lamb mortality rate was higher in twins. The year of birth, month of birth and sex of lamb significantly (p${\leq}$0.01) affected the cumulative lamb mortality rate at all ages. The least square mean of mortality during the final one-third of the lambing period was higher than the first and middle onethird of the lambing period. Male lambs were found to be at a higher risk of mortality than females. Birth weight of the lamb had a highly significant (p${\leq}$0.01) effect on lamb mortality at all ages as a quadratic regression. Direct and maternal heritability estimates of lamb mortality ranged from 0.01 to 0.13 and 0.01 to 0.05, respectively. Direct heritability increased with age of lamb, while maternal effects (genetic and common environmental) were important in the preweaning period. These results indicate that lamb mortality can be reduced first through farm management practices and secondly by genetic selection. Both animal and maternal effects should be considered in breeding programmes for reducing lamb mortality at preweaning.

• 정신신체의학
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• 제28권2호
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• pp.108-115
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• 2020

연구목적 본 연구는 한국 기혼 여성에서 만성적인 친밀한 관계에서의 폭력이 자살사고에 미치는 영향에 대해 조사하였다. 방 법 2014년부터 2018년까지의 한국복지패널의 자료를 사용하였으며 매년 조사된 설문을 이용하여 언어폭력 및 신체폭력이 우울증상 및 자살사고에 미치는 영향을 분석하였다. 나이, 교육수준, 경제수준, 음주, 종교, 만성질환, 가족관계 만족도, 사회관계 만족도 등을 공변량으로 하였다. 결 과 5년 간의 언어폭력 노출지수는 우울을 1.180배, 자살사고를 1.276배 높였으며 이는 우울증상의 영향을 보정해도 유의하였다. 반면, 5년 간의 신체폭력 노출지수는 우울을 1.486배, 자살사고를 1.362배 높였으며 우울증상의 영향을 배제하였을 때는 자살사고에 유의미한 영향을 주지 않았다. 결 론 이전에는 자살 사고가 없었던 여성에게 IPV가 장기적으로 지속되었을 때 우울증상의 유무와 상관없이 자살 사고를 높일 수 있다는 것을 밝혀낸 것에 의의가 있다. 위와 같은 결과를 고려하면 IPV를 경험한 여성에 대한 정신과적 개입이 자살률을 줄이는 데 도움이 될 것이다.

• Journal of Preventive Medicine and Public Health
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• 제53권5호
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• pp.293-301
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• 2020

Objectives: At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, some countries imposed entry bans against Chinese visitors. We sought to identify the effects of border shutdowns on the spread of the COVID-19 outbreak. Methods: We used the synthetic control method to measure the effects of entry bans against Chinese visitors on the cumulative number of confirmed cases using World Health Organization situation reports as the data source. The synthetic control method constructs a synthetic country that did not shut down its borders, but is similar in all other aspects. Results: Six countries that shut down their borders were evaluated. For Australia, the effects of the policy began to appear 4 days after implementation, and the number of COVID-19 cases dropped by 94.4%. The border shutdown policy took around 13.2 days to show positive effects and lowered COVID-19 cases by 91.7% on average by the end of February. Conclusions: The border shutdowns in early February significantly reduced the spread of the virus. Our findings are informative for future planning of public health policies.

• 한국전통조경학회지
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• 제32권3호
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• pp.183-190
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• 2014

경관의 가치를 보호하기 위한 문화재인 명승은 계곡이나 산악 등이 포함되므로 보호구역과 역사문화환경보존지역이 광범위하게 지정된다. 그러므로 명승의 지정에 따른 경관보호 효과의 검토가 수반되어야 한다. 이에 본 연구는 명승의 경관보호를 위한 효율적인 구역 설정 방법의 제시를 목적으로 하였다. 연구 대상으로 지정 비율이 가장 높은 계곡 중에서 '봉화 청암정과 석천계곡(명승 제60호)'을 선정하였다. GIS의 누적가시도 분석기법을 이용한 연구결과는 다음과 같다. 첫째, 계곡의 중요한 경관자원에서 역방향 누적가시도를 작성하여 조망점을 선정하는 방법을 제시하였다. 역방향 누적가시도는 명승에 대한 합리적인 조망점 선정에 활용될 수 있다. 둘째, 사람의 시야각과 경관자원의 배경에 대한 가시성을 고려한 경관분석 방법을 개발하였다. 셋째, 누적가시도를 활용하여 위계적인 명승의 경관보호 방안을 제시하였다. 넷째, 현장검증을 통해서 본 연구에서 제시한 구역 설정 방법의 실용성을 규명하였다.

• 한국ITS학회 논문지
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• 제15권6호
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• pp.138-149
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• 2016

본 연구는 가상주행 시뮬레이터 실험을 통해 악천후시 가변 제한속도 표출 효과를 검토하였다. 본 연구는 기상변화 없이 제한속도를 낮추어 표출한 경우와 기상이 변화되었는데도 제한속도를 낮추어 표출하지 못한 경우는 운전자의 기대심리를 위배한 것으로 기상 변화에 따라 속도를 감속 표출하는 것에 비해 상대적으로 안전 측면에서 바람직하지 못하다고 가정하고 이를 가상주행 시뮬레이터 결과를 통해 검토하였다. 본 연구는 운전자의 기대심리에 부합되는 정도를 나타내는 지표로 운전자 순응도를 선택하였고, 이를 정량화하기 위한 수단으로 표출 제한속도를 포함한 일정 속도구간 내 누적확률밀도를 이용하였다. 검토결과, 운전자의 기대심리를 위배하였다고 가정한 조건들이 비교그룹에 비해 상대적으로 운전자의 주행행태적 측면에서 부정적인 것으로 평가되었다.