• 한국건설관리학회논문집
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• 제17권3호
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• pp.71-80
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• 2016

대규모 복합 프로젝트(complex project) 또는 메가 프로젝트(mega project)들에서 확률적으로 공정계획을 수립하는 대표적인 방법이 PERT (Project Evaluation and Review Technique)기법이다. PERT기법은 작업공기의 불확실성에만 중점을 두고 작업간 연결관계는 Finish-to-Start(FS)관계로 제한되기 때문에 작업간 중복관계가 존재할 경우 작업간 연결관계의 불확실성에 대한 확률적인 추정이 불가능하다. PERT기법의 이러한 한계를 극복하기 위해, 작업간 다양한 중복관계들의 불확실성을 고려하여 사업전체 공기를 추정하는 방법으로 PLET (Probabilistic Linkage Evaluation Technique)기법을 제안되었다. 그러나 PLET 기법에 의한 사업공기 추정은 작업간 연결관계의 불확실성만을 고려할 뿐, PERT기법에서의 작업공기에 대한 불확실성은 고려하지 않으므로, 완전한 사업공기 추정방법이라 할 수 없다. 본 논문은 작업공기의 불확실성을 고려하는 PERT기법과 작업간 연결관계의 불확실성을 고려하는 PLET기법을 결합시켜 사업공기를 추정하는 통합 모델을 제안하고 확률적 타당성을 검증한다. 그리고 통합 모델의 일정계산방법을 제시하고 이를 실제사례에 적용하여 검증함으로써, 고위험 건설사업의 공정계획을 수립할 때 보다 폭넓고 다양한 위험요인들을 통합적으로 고려하는 확률적 사업공기 추정 방법을 제안하는 것이다.

• 대한토목학회논문집
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• 제38권6호
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• pp.839-850
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• 2018

집중호우에 의한 도시 유역의 침수 피해가 도시화에 따라 증가하는 추세이며, 이에 따라 정확하면서도 신속한 홍수예보 및 침수 예상도 표출이 필요하다. 특정 강우량에 따른 미지의 침수 범위를 예상하는 것은 도시 유역의 홍수에 대한 사전 대비에 매우 중요한 사안이며, 이를 위해 현재 홍수 예보와 관련된 정부기관에서 침수 피해 예상도를 주민들에게 제공하고자 하고 있다. 하지만, 특정 강우에 따른 정확한 침수 범위를 정량화하여 표출하는데 부족함이 있으며, 강우량과 지속시간에 따른 홍수의 크기에 대한 분석을 실시하고 수리학적 연계를 통한 준 실시간 침수범위 표출 방안을 고찰해야할 시기이다. 제시된 물리적 해석기반 자료를 이용하여 강우량-지속시간-침수량 관계곡선(Rainfall-Duration-Flooding quantity relationship curve, RDF)을 제시하고, 자율학습을 수행하는 자기조직화 특징 지도와 연계하여 미지의 침수 지도를 예측하였다. 예측한 침수 지도와 2차원 침수모형을 통한 결과를 비교하여, 제시된 방법론의 타당성을 검토하였다. 연구 결과를 통하여 중규모의 강우량 또는 빈도의 사상에 따른 미지의 침수범위를 제시하는데 용이할 것으로 판단된다. 더욱이 다양한 강우-월류량-홍수 양상을 내포하는 RDF 관계 곡선과 최적 침수예상도 데이터베이스를 구축함으로서 추후에 홍수예보의 기초자료로서 사용될 것이다.

• 한국콘텐츠학회논문지
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• 제9권10호
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• pp.159-167
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• 2009

방송에서 TV 드라마의 비중과 영향력이 커지면서, TV 드라마에 대한 많은 연구들이 이루어지기 시작했다. 그러나 이들 연구들은 시청률에 영향을 주는 시청동기, 수용행태 등에 관한 수용자 연구와 드라마 서사구조의 사회적 의미를 분석한 것들이 대부분이었고, TV 드라마의 영상제작기법과 연관된 연구는 시청률과 영상제작기법의 상관성, 시대별 영상제작기법 변천과정, 영화와 TV드라마의 영상제작기법 비교 등과 같은 제한된 수의 연구들이 이루어졌지만, 드라마의 내용과 영상제작기법의 관계를 조명한 연구는 전문한 실정이다. 따라서 본 연구에서는 텔레비전 편성에서 뿐만 아니라 산업적 가치 측면에서도 그 비중이 커지고 있는 텔레비전 드라마의 내용상의 장르와 영상제작기법의 상관성을 분석해보고자 한다. 표본 추출을 위하여 TNS 미디어 코리아에서 제시한 2004년부터 2008년까지의 연간 '시청률 톱 100' 자료를 바탕으로, 이 기간 동안 방송된 역사드라마, 멜로드라마, 홈드라마 중 가장 시청률이 높은 드라마를 각 장르별로 5편씩 총 15편의 드라마에서 8,210개 샷들을 추출하여 이들의 영상제작기법을 비교 분석하였다. 분석결과 역사드라마에서는 홈드라마나 멜로드라마에 비해 클로즈업과 롱샷 그리고 트래킹을 상대적으로 많이 사용하였으며, 샷의 지속시간은 짧은 반면 장면의 지속시간은 긴 것으로 나타났다. 반면 홈 드라마와 멜로드라마에서는 역사드라마에 비해 웨이스트샷이 상대적으로 많이 사용되었으며, 샷의 지속시간은 긴반면, 장면의 지속시간은 상대적으로 짧게 나타났다.

• International Journal of Precision Engineering and Manufacturing
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• 제9권3호
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• pp.82-84
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• 2008

A surface encoder based on the Half-shaded square pattern (HSSP) is presented. The HSSP working as reference grid is composed of the straight lines which are easy to be fabricated and make measuring time short. Since the periodic cell is separated in ON/OFF by the $45^{\circ}$ straight line, the duration from the starting point of scanning to the first rising edge and the duty cycle of the pulse train vary with respect to the position of the starting point. And the relationship between X and Y position and the duration, and duty cycle is described in the simple linear equation. Therefore, it is possible to measure X and Y position with the measured duration and duty cycle without calculating load. Through the test set-up, the feasibility of the proposed surface encoder was verified. Also the future works for improvement of performance were suggested.

• 한국경영과학회지
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• 제19권3호
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• pp.139-149
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• 1994

In many project-oriented production systems, e. g., shipyards or large-scale steel products manufacturing, resource loading by an activity is flexible, and the activity duration is a function of resource allocation. For example, if one doubles the size of the crew assigned to perform an activity, it may be feasible to complete the activity in half the duration. Such flexibility has been modeled by Weglarz [13] and by Leachman, Dincerler, and Kim [7[ in extended formulations of the resource-constrained poject scheduling problem. This paper presents a new algorithmic approach to the problem that combines the ideas proposed by the aforementioned authors. The method we propose involves a two-step approach : (1) solve the resource-constrained scheduling problem using a heuristic, and (2) using this schedule as an initial feasible solution, find improved resource allocations by solving a linear programming model. We provide computational results indicating the superiority of this approach to previous methodology for the resource-constrained scheduling problem. Extensions to the model to admit overlap relationship of the activities also are presented.

• 보건의료산업학회지
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• 제12권4호
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• pp.219-228
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• 2018

Objectives : This study was conducted to examine the relationships between Korean adult's daily hours of sleep, depression, and suicidal thoughts using data from the 7th National Health and Nutrition Survey. Methods : This study utilized a depression screening tool, the 9-item Patient Health Questionnaire (PHQ-9), for the 6,355 participants of the health and mental health survey. T-tests, cross analysis, correlation analysis, and logistic regression analysis were used. Results : The results showed that sufficient hours of sleep decreased depression. The depression score for females (3.19) was significantly higher than for males (2.10; p<.001). The participants in the depression group slept less than 7 hours per day (p<.01). Conclusions : The study results showed a significant correlation between sleep duration and depression when health-related factors and social factors influencing sleep were controlled. The results also indicated that this correlation may vary based on gender. This study implies that further studies are necessary to identify the causal relationship between sleep duration and depression.

• Journal of Nutrition and Health
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• 제31권4호
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• pp.747-755
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• 1998

In order to study the relationship between body core temperature and adiposity , the core temperatures of normal weight female college students were measured during an instant-noodle lunch eaten in a laboratory at the ambient temperature of 22-24.8$^{\circ}C$. Ambient temperature was positively correlated with meal-start core temperature and meal duration. The difference between the peak postprandial and the meal-start core temperature was negatively correlated with body weight and BMI. This means that the thermogenic response induced by meal consumption was negatively associated with adiposity. Meal duration also showed a negative correlation with body weight, BMI, and hip girth. Thus, the obese eating style characterized by a rapid rate of food intake was also associated with adiposity in normal weight women. It was possibly a contributing factor in the development of obesity. In conclusion, adiposity is negatively associated with the difference between the peak postprandial and the meal-start core temperature and meal duration during a meal.

• Safety and Health at Work
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• 제12권1호
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• pp.102-107
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• 2021

Background: This study was conducted to identify the association between sleep duration and suicidal ideation among farmers in Korea. Methods: We used Safety for Agricultural Injuries of Farmers cohort data collected from September 2015 to June 2018, which was an agricultural survey on the health and behaviors of adult farmers in Jeju island, Korea. Results: A total of 964 participants were included in the analysis, and 3.7% of them were identified with having suicidal ideation. The frequencies of average daily sleep duration of <6 h (short sleep), 6-8 h (normal sleep), and >8 h (long sleep) were 24.4%, 70%, and 5.6%, respectively. Multivariate analyses revealed that short sleep duration was significantly associated with suicidal ideation compared with normal sleep duration (odds ratio = 2.49, 95% confidence interval = 1.07-5.77). Conclusion: Our findings suggest that short sleep duration in farmers result in higher suicidal ideation. Because individuals who have suicidal ideation often commit suicide, careful monitoring is required to prevent suicide in farmers with short sleep duration.

• Journal of Preventive Medicine and Public Health
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• 제56권5호
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• pp.458-466
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• 2023

Objectives: The association between long sleep duration and mortality is frequently attributed to the confounding influence of comorbidities. Nevertheless, past efforts to account for comorbidities have yielded inconsistent outcomes. The objective of this study was to evaluate this relationship using a large prospective cohort in Korea. Methods: The study included 114 205 participants from the Health Examinees Study, who were followed for a median of 9.1 years. A composite comorbidity score was developed to summarize the effects of 21 diseases. Using Cox proportional hazards regression, hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause, cancer, and cardiovascular mortality associated with sleep duration were estimated. These estimates were adjusted for socio-demographic factors, lifestyle factors, body mass index, and comorbidity score. Additionally, a stratified analysis by subgroups with and without comorbidities was conducted. Results: Throughout the follow-up period, 2675 deaths were recorded. After all adjustments, an association was observed between a sleep duration of 8 hours or more and all-cause mortality (HR, 1.10; 95% CI, 1.01 to 1.20). However, no such association was detected in the stratified analysis for the subgroups based on comorbidity status. Conclusions: Long sleep duration was found to be associated with all-cause mortality among Koreans, even after adjusting for comorbidities. Additional studies are required to explore the mechanism underlying the association between sleep duration and major causes of mortality.

• 대한의생명과학회지
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• 제9권4호
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• pp.223-229
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• 2003

The welding workers are frequently exposed to heavy metals such as manganese. Manganese is well evaporated into the air while welding. This study had been carried out to investigate the relationship of the blood manganese level to age, work duration, and smoking status among 128 welding workers in Gyeongnam and Jeonnam province from May to November, 2003. They showed high manganese level in the first health examination. Subjects were also classified for the investigation according to their smoking status as smokers and nonsmokers, work duration ($\leq$9, 10~9, 20$\leq$years), and ages ($\leq$29, 30~39, 40~49, 50$\leq$years). Blood manganese Jevels were analyzed by atomic absorption spectrophotometer (AAS). Mean blood manganese level was 1.62$\pm$0.56 $\mu\textrm{g}$/dl. In the comparison of blood manganese levels by age and smoking status, mean blood manganese levels of smokers in age of 20's, 30's, and 50's were 2.09$\pm$0.44 $\mu\textrm{g}$/dl, 1.94$\pm$0.33 $\mu\textrm{g}$/dl, and 2.l5$\pm$0.33 $\mu\textrm{g}$/dl, respectively. Blood manganese levels of smokers were significantly higher than those of non-smokers, showing no significant difference in the 40's. In the comparison of blood manganese levels by work duration, the blood manganese levels of smokers were the highest in the case of 10 to 19 years work duration. This study showed that the blood manganese levels were related to the smoking status, work duration, and age. Mean manganese levels of smokers showed higher than those of nonsmokers. It also showed that the length of work duration was related to the elevation of blood manganese levels. Among the welding workers, blood manganese levels of smokers were the highest over their age of 50's. In conclusion, smoking was the most significant risk factor to increase blood manganese levels. The further study will need analysis of the other factors related to manganese level elevation.