• 한국건축시공학회지
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• 제21권2호
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• pp.113-119
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• 2021

고분자는 고유의 경량성 및 강성으로 인해 건축 자재에 두루 적용되는 소재이다. 그러나 건축 산업에서 빈번히 발생하는 화재 사고에서 대형 화재로의 확산을 일으키는 가장 큰 원인 중 하나가 가연 특성을 지니는 고분자라고 할 수 있다. 따라서 이를 해결하기 위한 방안으로 고분자 소재에 난연제를 첨가하여 난연 특성을 부여하는 연구가 활발히 진행되고 있는 추세이다. 이 중에서도 유기 인계 난연제는 고분자와의 혼화성이 우수하며, 독성이 낮은 장점을 가지고 있어 많은 주목을 받고 있다. 이에 따라 본 연구에서는 건축자재용으로 사용되는 친환경 고분자인 폴리락타이드의 난연성능을 확보하기 위하여 알콕시아민 기반의 유기 인계 난연제 구조를 설계 및 합성하여 이의 효과를 확인하는 것을 목적으로 둔다.

• 한국해양공학회지
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• 제33권3호
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• pp.259-271
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• 2019

It is important to obtain reasonable predictions of the extent of the damage during maritime accidents such as ship collisions and groundings. Many fracture models based on different mechanical backgrounds have been proposed and can be used to estimate the extent of damage involving ductile fracture. The goal of this study was to compare the damage extents provided by some selected fracture models. Instead of performing a new series of material constant calibration tests, the fracture test results for the ship building steel EH36 obtained by Park et al. (2019) were used which included specimens with different geometries such as central hole, pure shear, and notched tensile specimens. The test results were compared with seven ductile fracture surfaces: Johnson-Cook, Cockcroft-Latham-Oh, Bai-Wierzbicki, Modified Mohr-Coulomb, Lou-Huh, Maximum shear stress, and Hosford-Coulomb. The linear damage accumulation law was applied to consider the effect of the loading path on each fracture surface. The Swift-Voce combined constitutive model was used to accurately define the flow stress in a large strain region. The reliability of these simulations was verified by the good agreement between the axial tension force elongation relations captured from the tests and simulations without fracture assignment. The material constants corresponding to each fracture surface were calibrated using an optimization technique with the minimized object function of the residual sum of errors between the simulated and predicted stress triaxiality and load angle parameter values to fracture initiation. The reliabilities of the calibrated material constants of B-W, MMC, L-H, and HC were the best, whereas there was a high residual sum of errors in the case of the MMS, C-L-O, and J-C models. The most accurate fracture predictions for the fracture specimens were made by the B-W, MMC, L-H, and HC models.

• 교육녹색환경연구
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• 제18권1호
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• pp.38-48
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• 2019

본 연구는 대학 연구실 사고 예방을 위해서 실험 전 이루어지는 형식적인 일상점검을 보다 실효성 있는 일상점검표를 제시하는데 목적이 있다. 이를 위해 현재 실시중인 일상점검표와 선행연구자료를 재구성하여, 이를 토대로 2차에 걸친 전문가 델파이 조사로 연구를 실시하였다. 그 결과 연구실 정리정돈 등 일반안전 4개, 기계 및 공구 조임부 이상여부 등 기계기구안전 3개, 전기분전반 주변 적재금지 등 전기안전 3개, 유해인자취급 및 관리대장 비치 등 화공안전 6개, 소화기 점검 등 소방안전 3개, 가스용기 점점 등 가스안전 5개, 손 소독기 관리상태 등 생물안전 1개, 기타 1개, 총 26개 항목을 일상점검표로 제시하였다. 관련 전문가들의 의견을 종합해 보면, 실질적인 일상점검을 위해서는 쉽고 간소화 된 일상점검표가 필요한 것으로 나타났다.

• Safety and Health at Work
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• 제12권2호
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• pp.147-153
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• 2021

Background: In this study, the association of work and demographic characteristics with different traffic offenses committed by food delivery riders in Greece was examined. Previous research has identified various factors related to risky driving however, there is a need for exploring the complex interrelationship of work-related factors underlying risky driving behavior. Materials and Methods: A 2-items uestionnaire was used exploring delivery riders demographic characteristics, terms of employment, issues of concern during work and type of traffic offenses committed. In total, uestionnaires were analyzed using logistic regression in order to identify characteristics independently associated with serious traffic offenses, namely, red-light running and helmet non-use. Results: The analysis showed that: (i) typical health and safety measures had no effect on serious traffic offenses, (ii) young age was related to both offenses however (iii) different sets of work conditions were associated with reports of red-light running (i.e. low work experience, use of personal vehicle for work, and payment by hour) and helmet non-use respectively (i.e. intense work pace, high tip income per day and low concern about vehicle condition). Conclusion: The above findings provide evidence that serious traffic offenses are manifestations of underlying conflict experienced by the riders between safety and various performance criteria. Each one of the two offenses is related to different rider profiles aiming to satisfy different goals, namely, those mainly trying to maximize profit non-helmet users and those, mostly inexperienced ones, trying to cope with work pressure red light runners. Potential regulatory measures to alleviate risky practices are discussed.

• 대한조선학회논문집
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• 제59권6호
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• pp.439-446
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• 2022

Efforts to reduce carbon dioxide(CO₂) emissions are being carried out due to climate environmental problems. Eco-friendly ships are also being developed, and various energy saving measures have been developed and applied. In ships, researches have been conducted in various fields such as electric propulsion system and energy saving devices. In addition, the development of ships using various renewable energy, such as kite using wind power and wind power generation, has been carried out. This paper proposes a plan to use renewable energy for ships by applying wave generators to small ships. In 2016, 130 small domestic ships drifted by sea due to discharge of starting storage batteries, and discharge cases accounted for the largest portion of the causes of domestic ship accidents. This is due to the excessive use of storage batteries for starting the main engine by departing in a weak storage battery state for small ships. Accordingly, two type wave power generators - opened flow wave power generator and enclosed vibrator type wave power generator - are developed for charging a starting storage battery when the ships are stationary at sea or port. Opened flow wave power generator utilizes the flow of fluid in the ship by using wave induced ship motion. Enclosed vibrator type wave power generator utilizes the pendulum kinetic energy located in a ship due to wave induced ship motion.

• Wind and Structures
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• 제35권6호
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• pp.405-418
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• 2022

The aerodynamic behaviour of a CRH high-speed train under three infrastructure scenarios (flat ground, embankment, and viaduct) in the presence of a crosswind was simulated using a 1/8th scaled train model with three cars and the IDDES framework. The time-averaged and instantaneous flow field around the model were examined. The employed numerical algorithm was verified through a wind tunnel test, and the grid and timestep resolution analyses were conducted to ensure the reliability of the data. It was noted that the flow around the rail line was different under different infrastructure scenarios, especially in the case of the embankment, which degraded the aerodynamic performance of the train under the crosswind. The flow around the train on the flat ground and viaduct was different, although the aerodynamic performance of the train was similar in both cases. Moreover, the viaduct accidents were noted to have the most critical consequences, thereby requiring the most attention. The aerodynamic performance of the train on the windward track of the embankment under the crosswind was worse than that of the train on the leeward track. But for the other two infrastructure scenarios, the aerodynamic performance of the train on the windward track is relatively dangerous, which is mainly caused by the head car. These observations suggest that the aerodynamic behaviour of the train on an embankment under a crosswind must be carefully considered and that certain wind protection measures must be adopted around rail lines in windy areas.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.3990-4002
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• 2021

CSPACE (Core meltdown, Safety and Performance Analysis CodE for nuclear power plants) for a simulation of severe accident progression in a Pressurized Water Reactor (PWR) is developed by coupling of verified system thermal hydraulic code of SPACE (Safety and Performance Analysis CodE for nuclear power plants) and core damage progression code of COMPASS (Core Meltdown Progression Accident Simulation Software). SPACE is responsible for the description of fluid state in nuclear system nodes, while COMPASS is responsible for the prediction of thermal and mechanical responses of core fuels and reactor vessel heat structures. New heat transfer models to each phase of the fluid, flow blockage, corium behavior in the lower head are added to COMPASS. Then, an interface module for the data transfer between two codes was developed to enable coupling. An implicit coupling scheme of wall heat transfer was applied to prevent fluid temperature oscillation. To validate the performance of newly developed code CSPACE, we analyzed typical severe accident scenarios for OPR1000 (Optimized Power Reactor 1000), which were initiated from large break loss of coolant accident, small break loss of coolant accident, and station black out accident. The results including thermal hydraulic behavior of RCS, core damage progression, hydrogen generation, corium behavior in the lower head, reactor vessel failure were reasonable and consistent. We demonstrate that CSPACE provides a good platform for the prediction of severe accident progression by detailed review of analysis results and a qualitative comparison with the results of previous MELCOR analysis.

• 한국컴퓨터정보학회논문지
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• 제27권2호
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• pp.61-69
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• 2022

배달산업이 COVID-19 상황과 함께 요식업을 중심으로 크게 성장함에 따라 배달업 종사자가 크게 증가했다. 그와 함께 개인형 모빌리티(Personal Mobility: PM)를 활용한 새로운 배달 형태가 등장했으며, 이륜차 혹은 PM 관련 사고는 꾸준히 증가하고 있다. 본 연구는 안전 배달 모니터링 환경을 구축하기 위해 PM의 주행 분석 장치의 제작한다. 이를 위해 주행 분석 장치와 장치에서 수집된 데이터를 클라우드 서버를 통해 처리하는 시스템을 구성했으며, 이 시스템을 통해 PM의 운전상황에서 운전 중 발생할 수 있는 특수한 상황(가/감속, 과속방지턱 통과)을 인식하고 기록하고자 한다. 그 결과 장치 내 측정 센서(IMU)에서 수집한 각속도, 가속도, 지자기 값을 통해 운행 여부 및 인도 주행 여부, 경사로 주행 여부를 판단해 낼 수 있었다. 이 기술은 기존의 영상기반 기록장치보다 약 1600배 이상의 주행 정보 저장 효율을 달성할 수 있었다.

• International Journal of Computer Science & Network Security
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• 제22권9호
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• pp.183-188
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• 2022

Recently, more and more researches aimed at the development of automated and autonomous ships are appearing in the scientific environment. One of the main reason is the need to solve the problems of safe navigation and reducing accidents due to human factor, as well as the ever-increasing problem associated with the lack of qualified maritime personnel. Development of technologies based on application of artificial intelligence also plays important role, after all for realization of autonomous navigation concept and enhancement of ship automatic maneuvering processes, advancement of maneuvering functions and elaboration of specific algorithms on prevention of close quarter situations and dangerous approach of ships will be required. The purpose of this work is the review of preconditions of occurrence of the autonomous ship navigation conception, overview of introduction stages and prospects for ship remote control based on unmanned technologies, analysis of technical and intellectual decisions of autonomous surface ships, main research tendencies. The research revealed that the technology of autonomous ship navigation requires further development and improvement, especially in terms of the data transmission protocols upgrading, sensors of navigation information and automatic control systems modernization, which allows to perform monitoring of equipment with the aim of improving the functions of control over the autonomous surface ship operation.

• 항공우주시스템공학회지
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• 제16권1호
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• pp.40-48
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• 2022

최근 AR기술을 접목한 UAV 기반 재난구조 시스템이 연구되고 있다. 일반적으로 실제 재난 현장과 유사한 환경에서 재난 구조 훈련을 진행하는 것은 높은 비용과 사고 위험이 야기된다. 본 논문에서는 AR 기술을 접목한 UAV 기반 재난구조 시스템의 운용을 구조요원이 저렴하고 안전하게 훈련할 수 있도록 VR 기술을 이용한 훈련 시뮬레이션 소프트웨어를 제안한다. 기존 시스템의 분석을 통하여 훈련을 가상화하기 위한 요구사항을 도출하고 Unreal Engine 및 Airsim API를 이용하여 제안하는 시뮬레이션 소프트웨어를 개발한다. 모의실험은 제안하는 시뮬레이션 소프트웨어가 기존 재난구조 플랫폼의 동작을 효과적으로 모의할 수 있음을 보여준다.