• International Journal of Naval Architecture and Ocean Engineering
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• 제10권6호
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• pp.762-781
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• 2018

This paper presents the ballistic armor performance examination and thickness estimation for the latest naval ship structure materials in the Republic of Korea. Up to date, research regarding methods of ballistic experiments establishing database on the latest hull structure materials as well as a precise method of estimating required thickness of armor against specific projectiles have been rarely researched. In order to build a database and estimate proper thicknesses of structure materials, this study used four structure materials that have been widely applied in naval ships such as AH36 steel, AL5083, AL5086, and Fiber Reinforced Plastics (FRP). A $7.62{\times}39mm$ mild steel core bullet normally fired by AK-47 gun was considered as a threat due to its representativeness. Tate and Alekseevskii's penetration algorithm was also used to calculate a correction factor (${\alpha}$) and then estimate the armor thickness of naval ship hull structure materials with a given impact velocity. Through live fire experiments, the proposed method performance difference was measured to be 0.6% in AH36, 0.4% in AL5083, 0.0% in AL5086, and 8.0% in FRP compared with the experiment results.

• 한국안전학회지
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• 제20권4호
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• pp.20-28
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• 2005

In this paper, the methodology for the reliability estimation of buried pipeline with longitudinal gouges and dent is presented and the limit state of buried pipeline is formulated by failure assessment diagram(FAD). The reliability of buried pipeline with defects has been estimated by using a theory of failure probability. The failure probability is calculated by using the FORM(first order reliability method) and Monte Carlo simulation. The results out of two procedures have been compared each other. It is found that the FORM and Monte Carlo simulation give similar results for varying boundary conditions and various random variables. Furthermore, it is also recognized that the failure probability increases with increasing of dent depth, gouge depth, gouge length, operating pressure, pipe outside radius and decreasing the wall thickness. And it is found that the analysis by using the failure assessment diagram gives highly conservative results than those by using the theory of failure probability.

• 동력기계공학회지
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• 제18권4호
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• pp.78-84
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• 2014

The estimation of deformation and strain for the twill-weave carbon fiber reinforced plastic composite(CFRP) during the test with a digital image correlation system were implemented experimentally. The carbon fiber reinforced plastic composites have been developed as the edge technology materials. The plain, twill and satin weave types are commonly used for the CFRP composites. Thus, it is essential to find the deformation characteristics for those types of CFRP more easily. Especially the DIC method can express the visual strain distributions at the full range of the interested areas in the structures. In this study, the mechanical properties of twill-weave CFRP composite and the variation of strains in a full field of the specimen were estimated. The experiments were performed under a tensile loading and 3-point bending test with strain gages. Futhermore the DIC deformation results were estimated for the comparison. The results showed the deformation and strain contours visually well in all region of the interested areas and so usefulness for the safety control of the structures.

• Structural Engineering and Mechanics
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• 제50권5호
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• pp.653-664
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• 2014

Wind fragility analysis provides a quantitative instrument for delineating the safety performance of civil structures under hazardous wind loading conditions such as cyclones and tornados. It has attracted and would be expected to continue to attract intensive research spotlight particularly in the nowadays worldwide context of adapting to the changing climate. One of the challenges encumbering efficacious assessment of the safety performance of existing civil structures is the possible incompleteness of the structural appraisal data. Addressing the issue of the data missingness, the study presented in this paper forms a first attempt to investigate the feasibility of using the expectation-maximization (EM) algorithm and Bayesian techniques to predict the wind fragilities of existing civil structures. Numerical examples of typical linear or hysteretic shear frames are introduced with the wind loads derived from a widely used power spectral density function. Specifically, the application of the maximum a posteriori estimates of the distribution parameters for the story stiffness is examined, and a surrogate model is developed and applied to facilitate the nonlinear response computation when studying the fragilities of the hysteretic shear frame involved.

• 대한임베디드공학회논문지
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• 제18권6호
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• pp.303-310
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• 2023

A single vision system limits the ability to accurately understand the spatial constraints and interactions between robots and dynamic workers caused by gantry robots and collaborative robots during production manufacturing. In this paper, we propose a 3D pose registration method for dynamic workers based on a multi-domain vision system for safety monitoring in manufacturing environments. This method uses OpenPose, a deep learning-based posture estimation model, to estimate the worker's dynamic two-dimensional posture in real-time and reconstruct it into three-dimensional coordinates. The 3D coordinates of the reconstructed multi-domain vision system were aligned using the ICP algorithm and then registered to a single 3D coordinate system. The proposed method showed effective performance in a manufacturing process environment with an average registration error of 0.0664 m and an average frame rate of 14.597 per second.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.19-33
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• 2024

In nuclear thermal-hydraulic system codes, most correlations used for vertical pipes, under downward two-phase flow, have been developed considering small pipes or pool systems. This suggests that there could be uncertainties in applying the correlations to accident scenarios involving large vertical pipes owing to the difference in the characteristics of two-phase flows, or flow conditions, between large and small pipes. In this study, we modified the Multi-dimensional Analysis of Reactor Safety KINS Standard (MARS-KS) code using correlations, such as the drift-flux model and two-phase multiplier, developed in a plant-scale air-inflow experiment conducted for a pipe of diameter 600 mm under downward two-phase flow. The results were then analyzed and compared with those based on previous correlations developed for small pipes and pool conditions. The modified code indicated a good estimation performance in two plant-scale experiments with large pipes. For the siphon-breaking experiment, the maximum errors in water flow for modified and original codes were 2.2% and 30.3%, respectively. For the air-inflow accident experiment, the original code could not predict the trend of frictional pressure gradient in two-phase flow as / increased, while the modified MARS-KS code showed a good estimation performance of the gradient with maximum error of 3.5%.

• 스마트미디어저널
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• 제12권11호
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• pp.57-66
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• 2023

본 논문에서는 시내버스 내 CCTV 시스템을 활용, 비전AI 기반의 승하차 승객 의도를 예측하여 사고방지가 가능한 시스템에 대해 연구한 내용을 기술한다. 본 시스템은 YOLOv7 Pose 모델과 Object Tracking 기술을 활용하여 버스 내부의 승객을 감지하고 추적하며, LSTM 모델을 활용하여 승객의 승하차 여부를 예측한다. 시스템은 버스 내 CCTV 단말기 상에 설치 가능하여 운전 중 어느 때에나 승하차 여부 예측 결과를 시각적으로 확인할 수 있으며, 운전자에게 자동 알람을 주어 승하차 시 일어날 수 있는 사고를 예방할 수 있다. 테스트 결과, 승객의 승차 의도를 분석하는 채널 A와 하차 의도를 예측하는 채널 C에서 각각 0.81과 0.79의 정확도를 달성하였으며, 실시간성을 보장하기 위해 GPU 환경에서 초당 최소 5 프레임 이상의 분석이 가능하다는 것을 확인하였다. 본 알고리즘을 통해 시내버스 운행 중의 승객 승하차 과정을 모니터링하고, 그 안전과 편의성에 도움을 줄 것으로 생각된다. 추후 하드웨어가 발전하고, DB를 통해 데이터가 많이 수집된다면, 이 또한 다양한 안전 관련 지표로의 확장이 가능할 것이다. 더불어 본 알고리즘은 추후 자율주행 버스 상용화 시, 인간을 대신하여 승객 안전에 더욱 핵심적인 역할을 수행할 것이라 생각되며, 기타 지하철 및 승객이 내리고 탈 수 있는 모든 대중교통 환경에의 확장 또한 가능하여 대중교통의 안전화에 도움을 줄 것으로 생각한다.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.376-380
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• 2006

Temperature distribution measured to estimate the condition of an electrical apparatus is an absolute reference for the apparatus conditions and the difference between the reference temperature and the current temperature. Because of passive thermography, without the external thermal stimulation, the difference in surface temperature between the region of interest and back ground shows that the results can apply only to the estimation or the monitoring for the condition of loose terminal and the overload pertaining to the rise in temperature. However, a thermal diffusion in the active thermography is differently generated by the structure and condition of the surface and subsurface. This paper presents a nondestructive test using this behavior and deals with the results by heat injection and cooling to the apparatus. The buried discontinuity of subsurface could be detected by these techniques.

• International Journal of Human Ecology
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• 제6권2호
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• pp.63-72
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• 2005

This paper considered the impact of changing the product liability rule from consumer to producer liability on product safety under asymmetric information. In particular, it has been attempted to remove several constraints on antecedent studies. The main results of the study are as follows: under the misperception of the risk on a product, consumers may underestimate the probability of product failure. In this case, the accident rate can be lowered under the producer's liability rule. However, even under the asymmetric information, a consumer's estimation on the probability may be converged with the expected risk level, which could be called the 'rational expectation.' In this situation the probability of product failure can be lowered under the strict liability with contributory negligence. Additionally, it is possible to reduce the probability of product failure when a legal rule that imposes liability on cheapest cost avoider is admitted.

• 한국안전학회지
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• 제22권4호
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• pp.37-42
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• 2007

Flash points for the flammable binary systems, n-propanol+acetic acid and n-propanol+n-propionic acid, were measured by Cleveland open cup tester. The Raoult's law, the van Laar equation and the UNIQUAC equation were used for predicting flash points and were compared with experimentally-derived data. The calculated values based on the van Laar and UNIQUAC equations were found to be better than those based on the Raoult's law. And the predictive curve of the flash point prediction model based on the UNIQUAC equation described the experimentally-derived data more effectively than was the case when the prediction model was based upon the the van Laar equation.