• 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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2344-2352
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• 2000

Mechanical joints such as bolted or riveted joints are widely used in mechanical components. The reliable determination of the stress intensity factors for cracks in bolted joints is needed to evaluate the safety and fatigue life of them. The weight function method is an efficient technique to calculate the stress intensity factors for various loading conditions because only the stress analysis of an uncracked model is required. In this paper the mixed-mode stress intensity factors for cracks in bolted joints are obtained by weight function method, in which the coefficients of weight function are determined by finite element analyses for reference loadings. Critical inclined angle that mode I stress intensity factor becomes maximum is determined and the effects of crack length and the magnitude of clearance on critical inclined angle are investigated.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.142-148
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• 2022

In this paper, the weight reduction design of the yaw gearbox for wind turbine was performed through the finite element analysis method, and the stability was checked by performing the critical speed analysis. The weight reduction product can improve engine efficiency, save parts materials, and earn economic benefits. The yaw gearbox is lightweighted with the goal of achieving a safety rate of 1.3 or higher for wind turbine as indicated by IEC61400-1. In order to reduce the weight of the carrier, a topology optimization method was performed. The safety factor was verified by performing finite element analysis on the carrier. In addition, the housing and carrier were modeled using the finite element method, and the gear train was modeled using MASTA. For the yaw gearbox, the housing and carrier FE model and the gear train model were connected by the partial structural synthesis method to perform the rotational vibration analysis. Vibration excitation sources are mass unbalance and gear mesh frrequemcy, and as a result of the critical speed analysis, it was found that there was no resonance within the operating speed range.

• Journal of Auto-vehicle Safety Association
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• v.13 no.4
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• pp.26-32
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• 2021

This study is intended to augment the Roof strength test being evaluated by IIHS (Insurance Institute for Highway Safety). In order to find solutions for increasing Roof Crashworthiness Evaluation SWR (Strengthto-weight ratio). This study introduces that Integrated Connection Structure Between Center Pillar and Roof Center Rail is proposed as a critical solution.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.269-276
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• 2004

This study tried to figure out the framework of safety culture in railway industry to analyze root causes of railway incidents and accidents at Korean National Railway. Through the literature survey, authors found some critical dimensions common to railway safety culture such as employees' belief in the managers' management weight on safety and productivity, recognition of safety importance, risk taking attitude, practice of safety meeting before and after doing work, communication between management and employees and among drivers, traffic managers and infrastructure maintenance workers, safety reporting practice, safety and performance appraisal, effectiveness of safety audit, safety training, work place arrangement, incidents and accidents investigation, and safety knowledge management.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.114-121
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• 1997

Helical anchors are foundation structure that designed to resist uplift loads are installed by applying in load to shaft while rotating it into the ground. These can be a cost effective means of proving tension anchorage for foundation where soil conditions permit their installation because of ease of installation. At present time, tapered helical anchors are commonly used to carry uplift loads. The uplift capacity includes the following factors : the height of overburden above the top helix, the resistant along a cylinder, the weight of the soil in the cylinder and suction force. In order to make clear behavior characteristics of helical anchors with pullout, model tests were conducted with respect to various embedment depth, space of helix, shape of helix. Based on the experimental study, the following conclusions are drawn. 1) The uplift capacity of multi helical anchors increase with embedment ratio of anchors The increase is smooth after critical uplift capacity. 2) Critical breakout factors and critical embedment ratio of multi helical anchor exist 7∼8, 4∼6 respectively. 3) Variation of uplift capacity with helix spaces show down after S/D=5. 4) Critical breakout factors of helical anchor in the laboratory test are similar to Das's theory.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.165-174
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• 2010

TTG-blocks are concrete blocks designed to be paved around the bridge piers in order to protect the channel bed from local scour. In this study roughness coefficient of T.T.G- blocks are investigated through the hydraulic model test. And critical safety weight of TTG-blocks is derived in terms of Reynolds number for each individual block and group of linked blocks. Flume experiments show that a performance of TTG-blocks is effective to protect the river channel bed from local scour at bridge piers if it is assessed using with geotextile mat under blocks or designated gravels for filling in holes of blocks.

• Journal of the Korean Society of Safety
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• v.18 no.4
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• pp.143-147
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• 2003

The present investigation examined hammering performance, physiological response, preceived exertion, and user preference with regard to hammering in vertical (wall) and horizontal (bench) orientations, and with regard to using two different hammers. Ten male subjects participated in the experiment. The results support previous findings that horizontally oriented hammering is faster than vertically oriented hammering. In addition, the results suggest that hammer differences can affect hammering performance and perceived exertion; although, the exact contributions of specific design characteristics could not be quantitatively determined. However, participants subjectively identified handle design, weight, and mass distribution as critical factors.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.22-26
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• 2013

The purpose of this study was to improve the design of a mooring line by attaching a lumped mass to it on the seabed. A numerical analysis of the redesigned mooring system is performed to analyze the effect of the weight of the attached lumped mass using the commercial software Orcaflex. The ultimate tension of the mooring system with the lumped mass is compared with that of a bare mooring line in the original design. An appropriately designed weight for the lumped mass is found to induce a critical lifted point in the mooring line by floater motion in the ultimate condition to move toward the floater position from the anchor point, while maintaining a similar safety factor for the mooring line. On the other hand, it is shown that excess weight for the lumped mass induces snapping in a mooring line, resulting in low safety factor for the mooring system. The distance between lumped weights is shown to be a minor parameter affecting the safety of a mooring line, although a shorter line has an advantage from an economic point of view. Using the optimal weight for the lumped mass attached to the mooring line on a seabed reduces the mooring line length and installation area occupied by a mooring system under real sea conditions.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 1992.07a
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• pp.33-45
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• 1992

The sanitation inspection is the most frequently used procedure to protect foods prepared in foodservice establishments. In order to enhance foodservioe inspections and to improve post-inspection remedial measures, more practical evaluation methods for sanitation are required. The HACCP approach is based upon factors which contribute to foodborne disease rather than on factors which relate to aesthetics. Contributing factors for foodborne disease from foodservice establishments reported in USA, Canada, and England were analyzed to identify potential hazards during practical foodservioe operations. Hazards were classified at critical control points by risk ranking. Twenty-two observable practical indicators relating to each contributing factor were selected and adjusted to standardized procedures and hazard determiners at critical contral points. The weights for each inspection item were ranked as 1, 2, 3, 4 or 5 according to the risk level of contributing factors. And also application for the inspection item in different 6 types of work procedures was suggested for the use of specialized foodservice establishment and cafeteria, and of manager's self inspection in each establishment.