• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.723-735
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• 2019

The power-train is the most important component of an agricultural tractor. In this study, the strength of the driving gear transmission of an 82 kW-class tractor was analyzed using equivalent torque during plow tillage. The load measurement system consisted of an engine revolution speed sensor, torque-meters, revolution speed sensors for four axles, and pressure sensors for two hydraulic pumps. The load data were measured during plow tillage for four speed stages: F2 (2.78 km/h), F5 (5.35 km/h), F7 (7.98 km/h), and F8 (9.75 km/h). Aspects of the gear-strength such as bending stress, contact stress, and safety factors were analyzed under two torque conditions: the equivalent torque at the highest plow load for the F8 speed stage and the maximum engine torque. The simulation results using KISSsoft showed that the maximum engine torque conditions had a lower safety factor than did the highest equivalent torque condition. The bending safety factors were > 1 at all gear stages, indicating that gear breakage did not occur under actual measured operating conditions, nor under the maximum torque conditions. However, the equivalent torque condition in the contact stress safety factor was > 1, and the maximum torque condition was < 1 at the first gear pair. The method of analysis using the equivalent torque showed lower stress and higher safety factor than did the method using maximum torque. Therefore, when designing a tractor by applying actual working torque, equivalent torque method would support more reliable product development.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.248-255
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• 2009

After several damages by PWSCC were found in the world, USNRC and PNNL(Pacific Northwest National Laboratory) started the research on PWSCC under the project name of PINC. The aim of the project was 1) to fabricate representative NDE mock-ups with flaws to simulate PWSCCs, 2) to identify and quantitatively assess NDE methods for accurately detecting, sizing and characterizing PWSCCs, 3) to document the range of locations and morphologies of PWSCCs and 4) to incorporate results with other results of ongoing PWSCC research programs, as appropriate. Korea nuclear industries have also been participating in the project. Thermally and mechanically cracked-four mockups were prepared and phased array and manual ultrasonic testing(UT) techniques were applied. The results and lessons learned from the preliminary RRT are summarized as follows: 1) Korea RRT teams performed the RRT successfully. 2) Crack detection probability of the participating organizations was an average 87%, 80% and 80% respectively. 3) RMS error of the crack sizing showed comparatively good results. 4) The lessons learned may be helpful to perform the PINC RRT and PSI /ISI in Korea in the future.

• Journal of the Korean Society of Safety
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• v.21 no.4 s.76
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• pp.55-59
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• 2006

The radiation effects on electrical and mechanical properties of LDPE/EVA blends with various vinyl acetate contents were investigated. Radiation degradation of LDPE/EVA blends were studied by using gelation, volume resistivity, permittivity, dissipation factor, elongation at break, and E-modulus. As vinyl acetate contents increased in LDPE/EVA blends, electrical insulation characteristics were deteriorated, but flexibility was improved. As irradiation doses increased, electrical insulation characteristics were improved, but flexibility was deteriorated.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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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.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.495-503
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• 2016

Regulation for the testing and operation of autonomous vehicles on public roadways has been recently developed all over the world. For example, the licensing standards and the evaluation technology for autonomous vehicles have been proposed in California, Nevada and EU. But specific safety evaluation scenarios for autonomous vehicles have not been proposed yet. This paper presents safety evaluation scenarios for extraordinary service permission of autonomous vehicles on highways. A total of five scenarios are selected in consideration of safety priority and real traffic situation. These scenarios are developed based on existing ADAS evaluation and simulation of autonomous vehicle algorithm. Also, Safety evaluation factors are developed based on ISO requirements, other papers and the current traffic regulations. These scenarios are investigated via computer simulation.

• Journal of the Korean Society of Safety
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• v.31 no.6
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• pp.1-5
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• 2016

A bicycle is one of the most popular sporting goods in view of a sport activity and a human health. Metallic materials such as steel, aluminum, etc. were mainly used to the bicycle fork in the past. Nowadays, the carbon fiber reinforced composite materials are widely used to the manufacturing of a bicycle fork to reduce the weight and to increase the efficiency. Safety is a most important design parameter of a bicycle fork even if the weight and cost reduction are important. Bicycle failure may happen at the critical spot of a bicycle fork and cause the accident. In this paper, the composite bicycle fork will be analyzed to secure the safety and detect a critical spot by using the finite element method with Tsai-Wu failure criterion. The stress data were obtained for the laminated composites with various number of plies and fiber orientation under the bending load. Thus, design concept of a bicycle fork was proposed to secure the safety of a bicycle. The finite element analysis results show that the connection area between a steer tube and a fork blade is critical spot, and 75 or more layers of 0 degree are needed to secure the safety of a bicycle fork.

• Korean Journal of Agricultural Science
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• v.47 no.2
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• pp.327-335
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• 2020

The purpose of this study was to analyze the load distribution and contact safety factor for the power take off (PTO) gear of a 71 kW class agricultural tractor. In this study, a simulation model of the PTO gear-train was developed using Romax DESGINER. The face load factor and contact safety factor were calculated using ISO 6336:2006. The simulation time was set at 2,736 hours considering the lifetime of the tractor, and the simulation was performed for each PTO gear stage at the engine rated power conditions. As a result of the simulation, the face load factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.644, 1.632, and 1.341, respectively. The contact safety factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.185, 1.216, and 1.458, respectively. As the PTO gear stage was increased, the face load factor decreased, and the contact safety factor increased. The load distributions for all the PTO gears were concentrated to the right of the tooth width. This causes stress concentrations and shortens the lifespan of the gears. Therefore, it is necessary to improve the face load factor and the contact safety factor with macro-geometry and micro-geometry.

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.329-334
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• 2006

This paper presents the evaluation of LPG (Liquefied petroleum gas) regulators for home use. For the evaluation, several properties of the regulators were experimentally analyzed, such as the operation of safety device, the adjusting and lock-up pressure, the adjusting spring and the diaphragm, with respect to the used time of the regulators. Experimental results showed that the initial operation performances of regulators were degraded with increase of the service time and also showed that the degradation of the performance and material property could become serious after about six-year-use of the regulators.

• 한국가스학회:학술대회논문집
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• 2004.11a
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• pp.164-172
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• 2004

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.100-107
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• 2013

Although automotive safety technologies have been developed steadily, the efforts for pedestrian protection still seems to be insufficient. In a car-pedestrian accident, the structures such as the engine under a hood, the lower part of a windshield and the A-pillar are the major causes of fatal pedestrian injuries. Recently, there have been several studies on the active safety system to reduce the pedestrian injuries. The safety system consists of an active hood lift system and a pedestrian airbag. In this research, the safety performance of the active hood lift system and the pedestrian airbag is investigated by using the finite element method. The finite element model of the system is set up based on the head impact test, and the impact analyses are performed. The necessity and the usefulness of the safety system are verified.