• 한국안전학회지
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• 제37권1호
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• pp.70-77
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• 2022

The total number of Korean restaurants using delivery applications has substantially increased from 7.6% in 2018 to 11.2% in 2019. In 2020, the gross sales in the food delivery service market reached approximately 17 trillion won; this amount is virtually six times that in 2017 (i.e., 2 trillion won). Meanwhile, the annual average death toll of motorcycle riders increased by 3.5%, whereas the number of deaths due to other traffic accidents decreased by 8.2%. Consequently, the foregoing has become a critical social problem. Despite the continuing increase in the number of delivery riders due to the rapid expansion of the delivery industry, no appropriate safety management system has been established. Moreover, the government is experiencing difficulties in assessing the exact situation because of the absence of competent authority. In this study, fundamental data on the characteristics of delivery work and motorcycle accidents were collected through surveys and interviews; then, the influencing factors of traffic accidents were analyzed. Different influencing factors were identified: work experience as a rider; number of deliveries; whether to accept delivery requests in transit; manner of accepting delivery requests; and traffic law violations, such as speeding (for faster delivery) and running a red light. Because the motorcycle delivery industry has a relatively low job-entry barrier (i.e., special qualifications are not required), the riding skills of riders must be improved, and delivery companies must be technically developed to achieve a safe working environment. The results of this study can be utilized as fundamental data for system development or structural improvement of the delivery industry.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2757-2772
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• 2023

The fluid retention effect of the Volume Control Tank (VCT) leads to a long time delay in Reactor Coolant System (RCS) concentration during the boration process. A coupled model combining a lumped-parameter sub-model and a computational fluid dynamics sub-model is currently used to investigate the concentration dynamic characteristic of RCS during the boration process. This model is validated by comparison with experimental data, and the predicted results show excellent agreement with experimental data. We provide detailed fields in VCT and concentration variations of RCS to study the interaction between mixing in VCT and the transient responses of RCS. Moreover, the impacts of the inlet flow rate, inlet nozzle diameter, original concentration, and replenishing temperature of VCT on the RCS concentration characteristic are studied. The inlet flow rate and nozzle diameter of VCT remarkably affect the RCS concentration characteristic. Too-large or too-small inlet flow rates and nozzle diameters will lead to unacceptable long delays. In this work, the optimal inlet flow rate and nozzle diameter of VCT are 5 m³/h and 58.8 mm, respectively. Besides, the impacts of the original concentration and replenishing temperature of VCT are negligible under normal operating conditions.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.457-463
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• 2009

The earthwork is essential procedure for all civil engineering projects. Because of its importance in terms of cost and time, it should be managed effectively. In light of this, The Intelligent Excavating System (IES) research consortium has established to improve the productivity, quality and safety of current excavating/earthwork system by the Ministry of Land, Transportation and Maritime Affairs (MLTM) of Korea. This paper summarizes ongoing research aimed at development knowledge and presents a framework of task planning and visualization system for IES. The task planning and visualization system consists of three functions. 1) Using digital terrain model which created by 3D laser scanner, the system can divide it and generates global/local work area so that the excavator can work through the area. 2) In order to operate and/or control the excavator, the system exports the location, paths of boom, arm and bucket data of the excavator to control center. 3) The task planning system is visualized on the computer programming aided-graphic interface which simulates the planned work processes and eventually assists the operator for the control of the excavator. The case study which we have performed, demonstrates the effectiveness of the proposed system.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.3068-3084
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• 2021

Investigations of large commercial aircraft impact effect on nuclear power plant (NPP) buildings have been drawing extensive attentions, particularly after the 9/11 event, and this paper aims to experimentally assess the damage and vibrations of NPP buildings subjected to aircraft crash. In present Part I, two shots of reduce-scaled model test of aircraft impacting on NPP building were carried out. Firstly, the 1:15 aircraft model (weighs 135 kg) and RC NPP model (weighs about 70 t) are designed and prepared. Then, based on the large rocket sled loading test platform, the aircraft models were accelerated to impact perpendicularly on the two sides of NPP model, i.e., containment and auxiliary buildings, with a velocity of about 170 m/s. The strain-time histories of rebars within the impact area and acceleration-time histories of each floor of NPP model are derived from the pre-arranged twenty-one strain gauges and twenty tri-axial accelerometers, and the whole impact processes were recorded by three high-speed cameras. The local penetration and perforation failure modes occurred respectively in the collision scenarios of containment and auxiliary buildings, and some suggestions for the NPP design are given. The maximum acceleration in the 1:15 scaled tests is 1785.73 g, and thus the corresponding maximum resultant acceleration in a prototype impact might be about 119 g, which poses a potential threat to the nuclear equipment. Furthermore, it was found that the nonlinear decrease of vibrations along the height was well reflected by the variations of both the maximum resultant vibrations and Cumulative Absolute Velocity (CAV). The present experimental work on the damage and dynamic responses of NPP structure under aircraft impact is firstly presented, which could provide a benchmark basis for further safety assessments of prototype NPP structure as well as inner systems and components against aircraft crash.

• 해양환경안전학회지
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• 제18권5호
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• pp.461-467
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• 2012

$500{\mu}m$의 수력직경을 가진 마이크로 채널에서 유동 비등 시 물에 대한 마찰 압력 강하를 측정하기 위한 실험적 연구를 수행하였다. 실험은 열 유속 $100-400kW/m^2$, 증기건도 0-0.2 그리고 질량 유속 $200-600kg/m^2s$의 범위에서 이루어졌다. 유동 비등 시 마찰 압력 강하는 두 가지 모델을 사용하여 예측된다. 즉, 두 상의 속도가 동일하다고 가정한 균질 모델과 두 상 사이에 서로 다른 속도를 가지는 분리류 모델로 분류된다. 실험결과 이상 마찰 승수는 질량 유속이 증가함에 따라 감소한다는 것을 알 수 있었다. 측정된 압력 강하 데이터는 매크로 스케일과 미니/마이크로 스케일에서 제안된 기존의 여러 상관식들과 비교하였다. 균질 모델은 본 연구에서 고려한 실험 조건에서 29.4 %의 평균 오차내에서 마찰 압력 강하를 예측하였다.

• 한국안전학회지
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• 제30권3호
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• pp.135-140
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• 2015

Individuals who are vulnerable during disaster - including elderly, people with disabilities, children, pregnant women and etc - have a strong desire to protect themselves when disaster strikes since they are less capable to deal with the impact of disaster. Their experience and effort to keep them safe can be used as a resource to reduce the impacts of disaster not only for them but also for the community as a whole. Therefore, voluntary disaster management program will contribute to our society as a tool to respond effectively to disaster not only to meet the vulnerable's special needs but also to enhance community safety and public interest. This paper suggests a model that able "disaster vulnerable population" to take a leadership role in identifying risk and vulnerability factors, recommending disaster management strategy, and through that, contributing to enhance society's disaster plan. Therefore, this study aimed to surveyed individuals including "disaster vulnerable population" in order to assess the vulnerable's participation in disaster related volunteer work and surveyed associated institutions(volunteer centers, community centers) in order to research currently existing relevant programmes and the participation of "disaster vulnerable population" in such programmes. Also conducted focus group interview to explore voluntary program which will possibly integrate "disaster vulnerable population" into disaster management activities. As a result, three types of voluntary disaster management programs - education, public-relations, and activity - were suggested.

• Safety and Health at Work
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• 제11권1호
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• pp.61-70
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• 2020

Background: This study aims to assess whether the TSI PortaCount (Model 8020) is a measuring instrument comparable with the flame photometer. This would provide an indication for the suitability of the PortaCount for determining the workplace protection factor for particulate filtering facepiece respirators. Methods: The PortaCount (with and without the N95-Companion^TM) was compared with a stationary flame photometer from Moores (Wallisdown) Ltd (Type 1100), which is a measuring instrument used in the procedure for determining the total inward leakage of the particulate filtering facepiece respirator in the European Standard. Penetration levels of sodium chloride aerosol through sample respirators of two brands (A and B) were determined by the two measuring systems under laboratory conditions. For each brand, thirty-six measurements were conducted. The samples were split into groups according to their protection level, conditioning before testing, and aerosol concentration. The relationship between the gauged data from two measuring systems was determined. In addition, the particle size distribution inside the respirator and outside the respirator was documented. Linear regression analysis was used to calculate the association between the PortaCount (with and without the N95-Companion^TM) and the flame photometer. Results: A linear relationship was found between the raw data scaled with the PortaCount (without N95-Companion^TM) and the data detected by the flame photometer (R² = 0.9704) under all test conditions. The distribution of particle size was found to be the same inside and outside the respirator in almost all cases. Conclusion: Based on the obtained data, the PortaCount may be applicable for the determination of workplace protection factor.

• 응용통계연구
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• 제27권7호
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• pp.1243-1255
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• 2014

본 연구에서는 업종에 따른 다양한 근로환경 요인들을 파악하고 관련 분야의 산업안전보건 정책을 판단할 수 있도록 근로환경조사 기초자료를 분석하여 사회요인을 고려한 지수 및 지표 개발을 목표로 하였다. 지표개발을 위해 OECD에서 제시하는 지표개발 가이드라인과 해외의 지표개발 사례들을 벤치마킹하여 수행되었다. OECD의 압력-상태-대응 모형을 벤치마킹하여 건강과 관련 있는 지표들을 제시하였다. 근로환경조사의 압력-상태 건강관련 지표는 압력은 물리적 위험환경, 노동시간, 업무환경, 사회 환경으로 구성되었고, 이에 따른 상태 항목은 건강관련 항목으로 정신건강, 신체건강, 건강문제로 인한 결근, 업무 만족으로 구성되었다. 그 결과 임금근로자, 상용근로자, 관리자, 사무종사자, 전문가 및 관련 종사자, 50세 미만 근로자의 압력-상태 지표가 상대적으로 양호하였다. 반대로, 50세 이상, 자영업자, 일용 직, 농림어업 숙련직, 단순노무, 장치 기계 조립 근로자의 압력-상태 지표가 상대적으로 취약한 것으로 나타났다.

• 한국안전학회지
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• 제27권4호
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• pp.90-95
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• 2012

To prevent similar accidents with the basis of industrial accidents already occurred in industrial plants, it would be possible only after true causes are grasped. Unfortunately, however, most accident investigation carried out with the basis of legal regulation failed to grasp them so that similar accidents have been repeated without cease. This research aimed to find out differences between results from conventional accident investigation and those from human error analysis, and to draw out effective and practical counter-plans against industrial accidents occurred repeatedly in an autoglass manufacturing company. As for analysis, about 110 accident cases that occurred for last 7 years were collected, and by adopting the Comprehensive Human Error Analysis Technique developed by the previous researchers, not direct causes but basic fundamental causes that might induce workers to human errors were sought. In consequence, the result showed that facility factors or environmental factors such as improper layout, mistakes in engineering design, and malfunction of interlock system were authentic major accident causes as opposed to managerial factors such as personal carelessness or failure to wearing personal protective equipments, and/or improper work methods.

• Safety and Health at Work
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• 제3권4호
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• pp.294-297
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• 2012

Previous studies on the vast increase in suicide mortality in Southeast Asia have indicated that suicide rates increase in parallel with a rise in unemployment or during periods of economic recession. This paper examines the effects of economic recession on suicidal rates amongst agriculture, fisheries, and forestry workers in Korea. Monthly time-series gross domestic product (GDP) data were linked with suicidal rates gathered from the cause of death records between1993-2008. Data were analyzed using generalized additive models to analyze trends, while a polynomial lag model was used to assess the unconstrained time lag effects of changes in GDP on suicidal rate. We found that there were significant inverse correlations between changes in GDP and suicide for a time lag of one to four months after the occurrence of economic event. Furthermore, it was evident that the overall relative risks of suicide were high enough to bring about social concern.