• 제어로봇시스템학회논문지
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• 제15권8호
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• pp.823-830
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• 2009

For developing automotive parts and telematics devices the real car test often shows limitation because it needs high cost, much time and has the possibility of the accident. Therefore, a Vehicle Driving Simulator (VDS) instead of the real-car test has been used by some automotive manufactures, research centers, and universities. The VDS is a virtual reality device which makes a human being feel as if one drives a vehicle actually. Unlike actual vehicle, the simulator has limited kinematic workspace and bounded dynamic characteristics. So it is difficult to simulate dynamic motions of a multi-body vehicle model fully. In order to overcome these problems, a washout algorithm which restricts workspace of the simulator within the kinematic limits is needed, and analysis of dynamic characteristics is required also. However, a classical washout algorithm contains several problems such as time delay and generation of wrong motion signal caused by characteristics of filters. Specially, the classical washout algorithm has the simulator sickness when driver hardly turns brakes and accelerates the VDS. In this paper, a new washout algorithm is developed to enhance the motion sensitivity and improve the simulator sickness by using the vehicle tilt signal which is generated in the real time vehicle dynamic model.

• 한국게임학회 논문지
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• 제10권3호
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• pp.25-35
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• 2010

본 논문은 제품의 고장모드를 예측하고 제거하는 FMEA를 체감형게임의 안전성 평가척도에 적용함으로써 체감형게임의 사용가능성을 증진시키는 방법에 대한 논문이다. 체감형게임이 제공하는 작동화된 인터랙션이라는 특징 때문에 사용자들은 예상치 못한 사고들을 겪게 되었다. 이에 본 논문은 Wii 사고사례들 중 게임기기와 신체상해부위의 두 가지 분류 내의 위험요인(고장모드)들을 FMEA를 사용해 우선순위를 매겨보았다. 그 결과 게임기기에서는 TV가, 신체상해 부위에서는 손열상 및 타박상이 가장 큰 위험요인으로 나타났다. 이를 바탕으로 FMEA를 활용한 체감형게임 안전성 평가모델에서 가장 우선적으로 고려해야 할 안정성 평가 순위를 제공하고, 상이한 체감형게임 기기들 간의 일관성 있는 평가 가이드라인을 제공할 수 있는 기초를 마련하였다.

• 한국안전학회지
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• 제34권2호
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• pp.22-27
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• 2019

Bikers can be subjected to accidents during their bicycling. Helmets are only good, if any, for their head protection. A wearable airbag can protect the human neck area if it is properly designed. This airbag system is composed of an inflater and an airbag. The inflater contains a pressurized gas cylinder and a piercing device. The airbag is an inflatable fabric surrounding the human neck. When a bicycle accident happens, a sensor captures the motion of the biker and a microcomputer sends a signal to open a valve in the inflator to supply the pressurized gas to the airbag. An important issue of this system is that the airbag should be quickly inflated to protect the human neck. This paper deals with the airbag inflation time simulation and some issues to design a wearable airbag system. Also, a prototype was tested to show its feasibility using a human dummy mounted on a running cart.

• Nuclear Engineering and Technology
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• 제51권1호
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• pp.104-115
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• 2019

Since the Fukushima Daiichi accident, there has been an emphasis on the risk resulting from multi-unit accidents. Human reliability analysis (HRA) is one of the important issues in multi-unit probabilistic safety assessment (MUPSA). Hence, there is a need to properly identify all the human and organizational factors relevant to a multi-unit incident scenario in a nuclear power plant (NPP). This study identifies and categorizes the human and organizational factors relevant to a multi-unit incident scenario of NPPs based on a review of relevant literature. These factors are then analyzed to ascertain all possible unit-to-unit interactions that need to be considered in the multi-unit HRA and the pattern of interactions. The human and organizational factors are classified into five categories: organization, work device, task, performance shaping factors, and environmental factors. The identification and classification of these factors will significantly contribute to the development of adequate strategies and guidelines for managing multi-unit accidents. This study is a necessary initial step in developing an effective HRA method for multiple NPP units in a site.

• 센서학회지
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• 제31권1호
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• pp.64-68
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• 2022

Herein, we propose a LoRaWAN-based small draft system that can measure the ocean current flow (speed, direction, and distance) in real time at the request of the Coast Guard to develop a device that can promptly find survivors at sea. This system has been implemented and verified in the early stages of rescue after maritime vessel accidents, which are frequent. GPS signals often transmit considerable errors, so correction algorithms using the improved triangulation method algorithm are required to accurately indicate the direction of currents in real time. This paper is structured in the following manner. The introduction section elucidates rescue activities in the case of a maritime accident. Chapter 2 explains the characteristics and main parameters of the GPS surveying technique and LoRaWAN communication, which are related studies. It explains and expands on the critical distance error correction algorithm for GPS signals and its improvement. Chapter 3 discusses the design and analysis of small draft buoys. Chapter 4 presents the testing and validation of the implemented system in both onshore and offshore environments. Finally, Section 5 concludes the study with the expected impact and effects in the future.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1483-1490
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• 2021

Many studies are undertaken into nuclear power plants (NPPs) in preparation for accidents exceeding design standards. In this paper, we analyze the applicability of various wireless communication technologies as accident countermeasures in different NPP environments. In particular, a commercial wireless communication module (WCM) is investigated by measuring leakage current and packet error rate (PER), which vary depending on the intensity of incident radiation on the module, by testing at a Co-60 gamma-ray irradiation facility. The experimental results show that the WCMs continued to operate after total doses of 940 and 1097 Gy, with PERs of 3.6% and 0.8%, when exposed to irradiation dose rates of 185 and 486 Gy/h, respectively. In short, the lower irradiation dose rate decreased the performance of WCMs more than the higher dose rate. In experiments comparing the two communication protocols of request/response and one-way, the WCMs survived up to 997 and 1177 Gy, with PERs of 2% and 0%, respectively. Since the request/response protocol uses both the transmitter and the receiver, while the one-way protocol uses only the transmitter, then the electronic system on the side of the receiver is more vulnerable to radiation effects. From our experiments, the tested module is expected to be used for design-based accidents (DBAs) of "Category A" type, and has confirmed the possibility of using wireless communication systems in NPPs.

• 한국건축시공학회지
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• 제23권1호
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• pp.81-92
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• 2023

According to the 2020 industrial accident reports of the Ministry of Employment and Labor, the number of fatal accidents in the construction industry over the past 5 years has been higher than in other industries. Of these more than 50% of fatal accidents are initially caused by fall accidents. The central government is intensively managing falling/jamming protection device and the use of personal protective equipment to eradicate the inappropriate factors disrupting safety at construction sites. In addition, although efforts have been made to prevent safety accidents with the proposal of the Special Act on Construction Safety, fatalities on construction sites are constantly occurring. Therefore, this study developed a model that automatically detects the wearing state of the worker's safety helmet and belt using computer vision technology. In considerations of conditions occurring at construction sites, we suggest an optimization method, which has been verified in terms of the accuracy and operation speed of the proposed model. As a result, it is possible to improve the efficiency of inspection and patrol by construction site managers, which is expected to contribute to reinforcing competency of safety management.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.132-137
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• 2018

2015년 화학물질관리법 시행 이후 화학 사고 발생 수는 감소 추세에 있으나, 최근 인쇄회로기판(PCB) 제조시설에서 유사한 유형의 사고가 반복적으로 발생함에 따라 실험을 통해 사고 원인을 조사 분석하였다. 해당 사고는 인쇄회로기판 제조공정 내 에칭용액으로 사용한 유해화학물질인 염산과 과산화수소가 월류하여 발생한 사고로 작업자 부주의와 시설 관리 미흡이 주된 사고 원인으로 조사되었다. 사고 원인을 규명하기 위해 실시한 $Cl^-$의 함량 분석 결과 과산화수소 시료에서 66.85 ppm로 측정되어 사고 물질인 염산과 과산화수소의 혼합경로를 확인할 수 있었으며, 반응실험을 통해 반응열이 $50.5^{\circ}C$까지 발생함에 따라 PVC 저장탱크의 변형과 유독가스인 염소가스 발생을 확인하였다. 본 연구를 통해 인쇄회로기판 제조시설의 에칭공정에서의 과충전, 역류방지, 누출감지장치와 혼합방지를 위한 저장탱크 분리 설계 등 시설 안전 관리 방안과 해당 장치의 장외영향평가 검토 필요성을 제시하고자 하였다. 또한 동일 유형의 사고 재발 방지를 위하여 주기적인 시설 안전점검과 작업자의 안전교육 강화의 필요성에 대하여 논의하였다.

• 대한토목학회논문집
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• 제31권5D호
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• pp.679-687
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• 2011

시내버스 준공영제 시행이 시민들의 수송에 좋은 성과를 거두고 있지만 교통사망사고 증가에 따른 부작용이 발생하고 있다. 따라서 본 연구에서는 시내버스 준공영제 시행에 따른 교통사고 저감대책의 의사결정 모델 개발을 시도하였으며, 자료조사 및 분석방법은 교통전문가 설문과 계층분석법(AHP)을 활용하였다. 계층분석법(AHP)의 상위평가항목으로는 정량적 대책과 정성적 대책을 제시하였다. 하위평가항목 중 정량적 대책으로는 버스증차 및 안전장치 설치, 정류소 시설물 보완, 보행자 보호 시설물 보완, 교통안전 진단평가 및 보완으로 구성되어 있으며, 정성적 대책으로는 제도정비, 노선설계 보완, 교육 캠페인강화, 단속강화로 구성되었다. 분석결과를 살펴보면 첫째, 정성적 대책보다 정량적 대책에서 더 높은 가중치 결과가 나타났으며, 둘째, 정량적 대책으로는 정류소 시설물보완, 교통안전 진단평가 및 보완 순으로 나타났고, 셋째, 정성적 대책으로는 제도정비, 노선설계 보완 순으로 나타났다. 이런 결과는 향후 타시도의 교통사고 저감대책을 수립 시행할 경우 참고할 수 있는 기초 자료가 될 것이라고 사료된다.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.9-18
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• 2024

In-vessel retention through external reactor vessel cooling (IVR-ERVC) is a severe accident management (SAM) strategy that has been adopted and used in many nuclear reactors such as AP1000, APR1400, and light water reactor etc. Some reactor accidents have raised concerns about nuclear reactors among residents, leading to a decrease in residents' acceptability and many studies on SAM are being conducted. Experiments on IVR-ERVC are almost impossible due to its specificity, so fluid characteristics are analyzed through BALI experiments with similar condition. In this study, computational fluid dynamics (CFD) via Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) for BALI experiments were performed. Steady-state CFD analysis was performed on three turbulence models, and SST k-ω model was in good agreement with the experimental measurement temperature within the maximum error range of 1.9%. LES CFD analysis was performed based on the RANS analysis results and it was confirmed that the temperature and wall heat flux for depth was consistent within an error range of 1.0% with BALI experiment. The LES CFD analysis results were compared with those of the Lagrangian-based solver. LES matched the temperature distribution better than SOPHIA, but SOPHIA calculated the position of boundary between stratified layer and convective layer more accurately. On the other hand, Lagrangian-based solver predicted several small eddy behaviors of the convective layer and LES predicted large vortex behavior. The vibration characteristics near the cooling part of the BALI experimental device were confirmed through Fast Fourier Transform (FFT) investigation. It was found that the power spectral density for pressure at least 10 times higher near the side cooling than near the top cooling.