• 한국자동차공학회논문집
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• 제14권5호
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• pp.1-8
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• 2006

The Steer-By-Wire(SBW) system replaces complex mechanical linkages of the current steering system with electric motors, sensors, and electronic control units. However, the SBW system should guarantee its safety and reliability before commercialization, and therefore, a reliable and robust fault-tolerant technology has to be implemented. This paper proposes a fault-tolerant control algorithm for the SBW system. Based on careful analysis on propagation effects of sensor faults, a reliable fault-tolerant control strategy has been developed. The fault-tolerant controller consists of a fault detection part that monitors and detects faults in the steering wheel and road wheel sensors, and a reconfiguration part that switches to normal sensor signal based on fault detection information. It has been demonstrated by simulation that the proposed algorithm detects sensor faults accurately and enables reliable steering control under various dynamic fault situations.

• 한국안전학회지
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• 제28권6호
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• pp.42-48
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• 2013

Forensic engineering is the application of engineering principles covering the investigation of constructed facilities and systems that fail to perform as intended, causing personal injury or damage to property, environmental, economy etc. In the year 2012, two collapsed accidents of the large scaffolding system in national thermal power station occurred one after another, causing many casualties. In this study, we had performed to investigate the collapsed accident of scaffolding system occurred in the a thermal power station of two accidents. First, the investigation about the collapsed accidents site had performed to understand collapsed state and structures of the scaffolding system. Second, reviewing the materials concerning about the applied weight on the scaffolding system had performed. The applied weight is sum of the weights of the 15 workers, additional materials for coating work and dispersed and loaded shot ball on the foothold etc. the applied weight that calculated exceed more three times than the safe working load. Third, we had confirmed the install state of the materials of the scaffolding system by reviewing the quantity of the materials on the manual and the real system. Last, structural analysis had performed to evaluate structural integrity of the scaffolding system using Ansys. Through a series of this processes, the definite accidents causes of the collapsed scaffolding system revealed. Through these studies, the collapse accident that may occur in the scaffolding system in thermal power station can be minimized by performing specialized and systematic investigation on the accidents in terms of Forensic engineering.

• 대한임베디드공학회논문지
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• 제13권6호
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• pp.289-296
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• 2018

Drone detection in FMCW radar system needs complex techniques because a drone beat frequency is highly dynamic and unpredictable. Therefore, the current static signal processing algorithms cannot show appropriate detection accuracy. With dynamic signal fluctuation and environmental clutters, it can fail to detect a drone or make false detection. It affects to the radar system integrity and safety. Constant false alarm rate (CFAR), one of famous static signal process algorithm is effective for static environment. But for drone detection, it shows low detection accuracy. In this paper, we suggest neural network based FMCW radar system for detecting a drone. We use recurrent neural network (RNN) because it is the effective neural network for signal processing. In our FMCW radar system, one transmitter emits FMCW signal and four-way fixed receivers detect reflected drone beat frequency. The coordinate of the drone can be calculated with four receivers information by triangulation. Therefore, RNN only learns and inferences reflected drone beat frequency. It helps higher learning and detection accuracy. With several drone flight experiments, RNN shows false detection rate and detection accuracy as 21.1% and 96.4%, respectively.

• 한국응급구조학회지
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• 제1권1호
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• pp.71-86
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• 1997

This study is to suggest some developmental policies by analyzing the activities of first aid party in Kwangju and Chonnam regions for two years from Jan. 1, 1991 to the end of December, 1995. First, the residents in Kwangju and Chonnam regions have the sufficient benefits of emergency medical center, but it will be desirable that general hospital should be established and managed in Kohung peninsula which forms the wide island area far away from big cities. Second, the classification of the degree of severe case in the field by rescue members should be strengthened as the means which can reduce the number of patients transferred to the emergency room and the legal method which rescue members can select the medical agency. Third, children less than 10 are most frequent emergent patients and it is due to parent's indifference and children's in sensibility to safety. So the safely education in the course of infant and elementary education should be strengthened and the method which can keep the self safety through the legal system. Fourth, to increase the rate of emergency measure by rescue members, the reasons of fail of emergency treatment are suggested, the treatment results of each rescue member are analyzed every year and it is desirable that the system which can evaluate the personal ability should be introduced. Fifth, the medical accidents occurred in the case of medical act, by rescue members must lake the legal responsibility, but such a problem can he solved with the compensation of insurance system by government. Sixth, to reduce the time required for transfer, traveling service system for the fixed period in beach should be complemented and extended more and service system at ordinary times should be examined at mountains, the area of traffic jams and large special industrial park. Seventh, since service system with one team of two members of 119 rescue party in expressway cannot be mobilized when multiple accidents occur at the same time, it is considered that service system of two teams of four members should be extended. Eighth, first-aid service in expressway is conducted with rescue and emergency treatment by the rescue party at the same time, but the professional rescue lacks and it may result in the injury of patients. Therefore the creation of rescue party in expressway is the urgent problem.

• 한국가스학회지
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• 제22권1호
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• pp.78-85
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• 2018

본 연구를 통하여 반도체 FPD 제조설비 및 클린룸에 관련한 설비의 위험성분석과 그에 대한 근원적인 안전대책을 연구하고, 설비 및 환경의 특수성을 고려한 방폭 설계 모델링화를 검토하여 관련 설비의 설계 및 제작에 기술적인 기준과 근거로 활용하고자 하며, 아래와 같은 성과로서 향후 반도체 FPD 산업의 기술적 기준 수립 및 관련 산업에 기여할 것으로 생각한다. 1) 관련 국제 기술규격과 법령, 설비의 특성을 반영한 FAB 장비의 최적화된 폭발위험장소의 모델링 도출 2) FAB 장비 및 클린 룸의 특성을 고려한 위험설비의 안전성 확보 (Fool-Proof와 Fail Safe)를 위한 안전시스템 구축방안과 안전기준 및 대책 도출 3) 향후 FAB 장비의 방폭 설계에 대한 가장 효율적인 기준 적용을 통한 신규 FAB 장비의 방폭 성능의 유연성 확보하고 수립된 안전기준을 통한 설비와 안전시스템의 신뢰성 검증 절차 운영을 위한 "안전인증제도"의 자율적 향상화.

• 한국분말재료학회지
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• 제11권4호
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• pp.288-293
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• 2004

The application concept of using a fail safety filter on the filtering system is to prevent the particle leakage when the main filter element is broken at high temperature. In this study, the metal filters were fabricated by pressureless sintering method. The mixture of stainless steel powders and filler metal binder solved in the water solutions of 5% PVA was compacted to form the cylindrical filter without pressure. The compacted filter were sintered in the vacuum sintering furnace at 120$0^{\circ}C$ for 1 hour. The metal filter(produced with powder of 640-840 ${\mu}m$ size) having more than above 50% porosity, 500${\mu}m$ pore size, and permeability of 7.3${\times}$10$^{-11}$m$^{2}$ plugged within 2.5 minute to prevent the leakage of maximum slip particle size of less than 3${\mu}m$.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.139-144
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• 2003

This study was aimed to establish failure management plan of the rubber-tired AGT light rail vehicle for its safety case, which was developed according to the Korean standardized specifications for the light rail vehicle. Vehicular 9 failure modes anticipated during the system operation were considered, which are single malfunction of redundant equipment, malfunction of train radio, public address and air compressor, battery, main circuit NFB trip, on-board ATO control device malfunction, on-board ATP control device malfunction, fail of brake release, flat tire, train emergency door open.

• International Journal of Computer Science & Network Security
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• 제21권12spc호
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• pp.636-642
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• 2021

Vehicular Ad hoc Networks (VANET's) are gaining popularity in research community with every passing year due to the key role they play in Intelligent Transportation System. Their primary objective is to provide safety, but their potential to offer a variety of user-oriented services makes them more attractive. The biggest challenge in providing all these services is the inherent characteristics of VANET itself such as highly dynamic topology due to which maintaining continuous communication among vehicles is extremely difficult. Here comes the importance of routing solutions which traditionally are designed using strict layered architecture but fail to address stringent QoS requirements. The paradigm of cross-layer design for routing has shown remarkable performance improvements. This paper aims to highlight routing challenges in VANET, limitations of single-layer solutions and presents a survey of cross-layer routing solutions that utilize the information from the MAC layer to improve routing performance in VANET.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2292-2306
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• 2024

This study addresses cracks and fracture problems in engineering structures that may cause significant challenges and safety concerns, with a focus on pressure vessels in nuclear power plants. Comprehensive parametric three-dimensional mixed mode fracture analyses for inclined and deflected nozzle corner cracks with various crack shape aspect ratios and depth ratios in nuclear reactor pressure vessels are carried out. Stress intensity factor (SIF) solutions are obtained using FRAC3D, which is part of Fracture and Crack Propagation Analysis System (FCPAS), employing enriched finite elements along the crack front. Also, improved empirical equations are developed to allow the determination of mixed mode SIFs, K_I, K_II, and K_III, for any values of the parameters considered in the study. This study provides practical solutions to assess the remaining life and fail-safe conditions of nuclear reactors by providing accurate SIF determination.

• Earthquakes and Structures
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• 제18권3호
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• pp.285-296
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• 2020

Dams are important structures for management of water supply for irrigation or drinking, flood control, and electricity generation. In seismic regions, the structural safety of concrete gravity dams is important due to the high potential of life and economic loss if they fail. Therefore, the seismic analysis of existing dams in seismically active regions is crucial for predicting responses of dams to ground motions. In this paper, earthquake response of concrete gravity dams is investigated using the finite element (FE) method. The FE model accounts for dam-water-foundation rock interaction by considering compressible water, flexible foundation effects, and absorptive reservoir bottom materials. Several uncertainties regarding structural attributes of the dam and external actions are considered to obtain the fragility curves of the dam-water-foundation rock system. The structural uncertainties are sampled using the Latin Hypercube Sampling method. The Pine Flat Dam in the Central Valley of Fresno County, California, is selected to demonstrate the methodology for several limit states. The fragility curves for base sliding, and excessive deformation limit states are obtained by performing non-linear time history analyses. Tensile cracking including the complex state of stress that occurs in dams was also considered. Normal, Log-Normal and Weibull distribution types are considered as possible fits for fragility curves. It was found that the effect of the minimum principal stress on tensile strength is insignificant. It is also found that the probability of failure of tensile cracking is higher than that for base sliding of the dam. Furthermore, the loss of reservoir control is unlikely for a moderate earthquake.