• Structural Engineering and Mechanics
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• 제77권2호
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• pp.231-243
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• 2021

In this paper, a dynamic response mapping model of the wheel-rail system is established by using the support vector regression (SVR) method, and the hierarchical safety thresholds of the subgrade void are proposed based on the reliability theory. Firstly, the vehicle-track coupling dynamic model considering the subgrade void is constructed. Secondly, the subgrade void area, the subgrade compaction index K30 and the fastener stiffness are selected as random variables, and the mapping model between these three random parameters and the dynamic response of the wheel-rail system is built by using the orthogonal test and the SVR. The sensitivity analysis is carried out by the range analysis method. Finally, the hierarchical safety thresholds for the subgrade void are proposed. The results show that the subgrade void has the most significant influence on the carbody vertical acceleration, the rail vertical displacement, the vertical displacement and the slab tensile stress. From the range analysis, the subgrade void area has the largest effect on the dynamic response of the wheel-rail system, followed by the fastener stiffness and the subgrade compaction index K30. The recommended safety thresholds for the subgrade void of level I, II and III are 4.01㎡, 6.81㎡ and 9.79㎡, respectively.

• 한국신뢰성학회지:신뢰성응용연구
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• 제10권1호
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• pp.73-91
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• 2010

All activities relate to railway traffic involve risk and that these arise from a combination of the nature of operating activities. Proper management system is required to provide the organizational capability to reveal, analyse and address these weaknesses over time and in reasonably practicable ways, which will determine the rate at which risks can be further reduced. This paper presents a systematic risk analysis approach to safety planning and decision making, informed by a range of risk assessment techniques. An railway organization's safety management system is also presented that shows the approaches taken to minimize the external risks, and identify the shared risks and explain how they will be controlled through collaboration with others.

• 한국환경보건학회지
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• 제36권6호
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• pp.510-517
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• 2010

Phthalates, such as di (2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) have been proved to be teratogenics and endocrine disruptors, metabolized rapidly and excreted in the urine. In this study, a simultaneous analytical method for 10 phthalate metabolites, MnBP, MiBP, MBzP, MCHP, MEHP, MEHHP, MEOHP, MnOP, MiNP and MiDP, in human urines, based on switching system with on-line pretreatment column using HPLC-MS/MS has been developed. This method was validated according to the guideline of bioanalytical method validation of National Institute of Toxicological Research. Limits of detection range between 0.2 and 0.9 ng/ml for 10 phthalate metabolites. The calibration curves showed linearity in the range 0.997~0.999, and the results of the intra- and inter-day validations were in the range from 0.4 to 14.7% RSD and from 0.3 to 9.4% RSD, respectively. Recoveries of phthalate metabolites varied from 87.0 to 116.1%. This analytical method showed high accuracy and stable precision for all metabolites, and seems to be suitable for biomonitoring of phthalates in human urine.

• Carbon letters
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• 제2권1호
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• pp.72-75
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• 2001

The performance of Li-ion system based on $LiCoO_2$ and Graphite is well optimized for the 3C applications. The charge-discharge mode, the manufacturing process, the cell performance and the thermal reactions affecting safety has been explained in the engineering point of view. The energy density of the current LIB system is in the range of 300~400 Wh/l. In order to achieve the energy density higher than 500 Wh/l, the active materials should be modified or changed. Adopting new high capacity anode materials would be effective to improve energy density.

• 동력기계공학회지
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• 제15권3호
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• pp.12-17
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• 2011

Gears are useful for power transmission due to excellent power transmission performance, low cost, and compactness. In addition, gears have constant speed ratio, compact structure, and excellent efficiency. In order to transmit higher power, the new multi-range transmission requires gears which have greater strength than the existing transmission. This study evaluates stability and durability through gear analysis of the multi-range transmission in commercial vehicles using ROMAX-DESIGNER program. Also, strength design evaluation is carried out by the analysis results which are compared with gear strength theory of AGMA standard. Bending stress and contact stress on gears are lower than their allowable stresses. Therefore, we can evaluate the safety of the gear strength design in multi-range transmission.

• 환경영향평가
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• 제12권1호
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• pp.23-34
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• 2003

The emergency response modeling system CARIS has been developed at CCSM (Center for Chemical Safety Management), NIER (National Institute of Environmental Research) to track and predict dispersion of hazardous chemicals for the environmental decision support in case of accidents at chemical or petroleum companies in Korea. The main objective of CARIS is to support making decision by rapidly providing the key information on the efficient emergency response of hazardous chemical accidents for effective approaches to risk management. In particular, the integrated modeling system in CARIS consisting of a real-time numerical weather forecasting model and air pollution dispersion model is supplemented for the diffusion forecasts of hazardous chemicals, covering a wide range of scales and applications for atmospheric information. In this paper, we introduced the overview of components of CARIS and described the operational modeling system and its configurations of coupling/integration in CARIS. Some examples of the operational modeling system is presented and discussed for the real-time risk assessments of hazardous chemicals.

• 대한조선학회논문집
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• 제42권2호
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• pp.98-104
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• 2005

The mathematical models of hydrodynamic force and moment acting on a ship at low speed range should be established differently from the ones at nominal cruising speed range since a ship moves with large drift angle or rotates in a stationary position. We modified widely used Yoshimura's cross flow model in order to apply the system identification method to estimate parameters in the model. The apparatus and the procedure of free running model test were suggested so that the parameters in the model be estimated. The validity of our proposing modified model and test procedure was confirmed by comparison with the results of simulated model test.

• 자동차안전학회지
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• 제9권2호
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• pp.13-19
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• 2017

This paper presents safety assessment scenarios for cyclist autonomous emergency braking(AEB) system. To assess the safety performance of AEB in real traffic situation with limited number of scenarios, scenario should reflect the characteristics of real traffic collision cases. For this, statistic data of real traffic car-to-cyclist collision in Korea are analyzed. Many types of accidents are listed and categorized based on the movement of vehicle and cycle just before the collision. Then, the characteristics, main issues and limitations of each scenarios are discussed. Not only the test scenario itself but also the cost and time for the test are very important issues for the test scenarios to actually repeat the test for various systems. Also, the performance of AEB can be effected by the algorithm of AEB and the technical limitation of the sensors and hardwares. Therefore, required number of tests, possibility of dummy destruction and other technical issues are discussed for each scenarios. Based on these information, typical scenarios are selected. Also, using this information, vehicle speed range, cyclist speed and collision point are established. Proposed scenarios are verified and modified based on the vehicle test results. vehicle test was evaluated 5 times for each scenarios. Based on this results, final test scenarios are modified and proposed.

• 대한안전경영과학회지
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• 제10권1호
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• pp.83-90
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• 2008

Development of human-system interfaces (HSI) supporting the interaction between human and automation-based systems, particularly safety-critical sociotechnial systems, entails a wide range of design and evaluation problems. To help HSI designers deal with these problems, many methodologies from traditional human-computer interaction, software engineering, and systems engineering have been applied; however, they have been proved inadequate to develop cognitively well engineered HSI. This paper takes a viewpoint that HSI development is itself a cognitive process consisting of various decision making and problem solving activities and then proposes a design requirements-driven process for developing HSI. High-level design problems and their corresponding design requirements for visual information display are explained to clarify the concept of design requirements. Lastly, conceptual design of software system to support the requirements-driven process and designers' knowledge management is described.

• 한국산업융합학회 논문집
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• 제26권1호
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• pp.15-26
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• 2023

In this study, an end-effector robot which is a two-axis delta robot type for upper-limb rehabilitation is designed. It is not only rehabilitation functions that has designed robot but also mechanical and electrical safety devices were constructed to ensure patient safety. By constructing the two-axis delta robot is combined with an LM guide, the operating range and rigidity required for rehabilitation were secured. The electrical safety system which is required for the medical robot was designed, and a safety strategy was established to ensure patient safety and it is applied in the integrated safety circuit. The safety is considered in whole design process from the robot's mechanical design to the electric control unit.