• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.124-129
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• 2018

A forklift is used to lift materials above a height of 2 m. The width of the fork determines the weight of the material it can carry. In this paper, three models of fractured forklifts were analyzed to determine if the fracture was caused by load fatigue due to the width of the fork. The position of the fork was fixed on each model, and a 2.5 ton load was placed at the upper part of the fork. The width distances on each of three models were 500 mm, 750 mm and 1000 mm, and the maximum equivalent stresses were 237.5MPa, 227.62MPa and 230.99MPa, respectively. This analysis demonstrated that as the load increased with use of the wider fork, the fatigue life remained to be nearly equivalent irrespective of fork width among all three models. The results of this study contribute to the durability and safety design of forklifts.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.525-531
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• 2012

This study aims at the structural analysis of vibration and fatigue according to the configuration of engine mount. Maximum equivalent stress or deformation is shown at bracket or case respectively. As harmonic vibration analysis, the maximum displacement amplitude is happened at 4,000Hz. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' or 'Saw tooth' becomes most stable. In case of 'Sample history' or 'Saw tooth' with the average stress of 4,200MPa or 0MPa and the amplitude stress of -3,000MPa or 7MPa, the possibility of maximum damage becomes 70%. This stress state can be shown with 7 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design on engine mount by investigating prevention and durability against its damage.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.4
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• pp.673-679
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• 2013

This study investigates the strength durability of an automotive front bumper subjected to vibrations during driving. Through structural analyses,the maximum equivalent stresses of models 1 and 2 were found to be 187.09 and 278.4 MPa, respectively. The maximum deformations of models 1 and 2 were 1.3772 and 2.675 mm, respectively. As model 1 shows less deformation than model 2, itis stronger than model 2. Models 1and 2 show natural frequencies within 230 Hz as the range of the maximum harmonic response frequency. Models 1 and 2 have maximum amplitude displacements of 0.105 and 0.154 mm at critical frequencies of 159 and 110 Hz, respectively. As model 1 has a higher critical frequency than model 2, it has more strength durability than model 2. This study result can be effectively utilized for the design of a front bumper by investigating prevention against damage and its strength durability.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.68-74
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• 2014

This study analyzes structural stress and fatigue about three types of automotive wheels. As maximum equivalent stresses at 1, 2 and 3 types become lower than the yield stress of material and deformations become minute, theses types are thought be safe on durability. Type 2 model has the most fatigue life among three kinds of types and the rest of models with fatigue lives are shown in the order of type 1 and 3. As the most fatigue frequency of type 2 model happens at the state of average stress and amplitude stress on the stress range narrower than type 1 or 3, type 2 model becomes most stable. In case of type 2 with the state near the average stress of 0 MPa and the amplitude stress of 300MPa, the possibility of maximum damage becomes 30%. This stress state can be shown as the most damage possibility. These study results can be effectively utilized with the design on automotive wheel by anticipating and investigating prevention and durability against its damage.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.128-133
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• 2014

In this study, Two kinds of pad models with different configurations as the part of brake system are investigated by structural and fatigue analyses. As the maximum equivalent stress of model 2 becomes higher to the extent of 60% than that of model 1, model 2 can endure more load than model 1. In cases of two kinds of models, the maximum fatigue life at 'Sample history' becomes longer 60 times than 'SAE bracket history' and this life in case of 'SAE transmission' becomes longer 3.5 times than the case of 'SAE bracket history'. Maximum fatigue damages in cases of 'SAE bracket history', 'SAE transmission' and 'Sample history' at model 1 become higher than model 2. Model 2 is thought to have more fatigue durability than model 1. These study results can be effectively utilized with the design of brake pad by anticipating and investigating prevention and durability against its fatigue damage.

• Journal of Welding and Joining
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• v.6 no.3
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• pp.43-55
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• 1988

An experimental study was carried out to identify the fatigue fractue behavior of weld zone in generally rolled steel for marine structure. The bending an shear loads were applied simultaneously on the specimens to simulate real load condition for marine structure. The effect of the stress intensity factor under mode I with II loading condition on the initiation and the propagation of a crack were investigated, with particular emphaiss on mode II. When the $K_{II}$ stress intensiy factor in mode II was applied under mode I load condition, the growth behavior of a crack seems to be affected mainly by the anisotropic characteristic of materials. Especially, when the crack was located in and near the weld zone and parallel to th weld line, the propagation behaviour was turned out to be quite different from that of the base metal along the direction transverse to the weld line. In general, the propagation veiocity of the cracks in and near the weld zone was found to be slower that the velocity in base metal.

• Journal of Environmental Science International
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• v.5 no.3
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• pp.317-327
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• 1996

This study was performed to develop the biological treatment technology of wastewater polluted with heavy metals. Zinc-tolerant microorganism, such as Pseudomonas chlororaphis which possessed the ability to accumulate zinc, was isolated from industrial wastewaters polluted with various heavy metals. The characteristics of zinc accumulation in the cells, recovery of the zinc from the cells accumulating zinc, were investigated. Removal rate of zinc from the solution containing 100 mall of Zinc by zinc-tolerant microorganism was more than 90% at 48 hours after inoiulation of the microorganisms. A large number of the electron-dense granules were found mainly on thIn cell wall and membrane fractions, when determined by transmission electron microscope. Energy dispersive X- ray spectroscopy revealed that the electron-dense granules were zinc complex with the substances binding Heavy metals. The zinc accumulated into cells was not desorbed by distilled water, but more than 80% of the zinc accumulated was desorbed by 0.1M-EDTA. The residues of the cells after combustion at 55$0^{\circ}C$ amounted to about 21% of the dry weight of the cells. EDS analysis showed that the residues were comparatively pure zinc compounds containing more than 79% of zinc.

• Journal of Korean Neurosurgical Society
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• v.29 no.8
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• pp.995-1000
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• 2000

Objective : The authors reviewed 280 cases with intracranial arteriovenous malformations(AVMs) to identify risk factors of hemorrhage. Patients and Methods : From 1983 to 1997, a total 280 patients with AVMs were treated. Among them, 64% had a history of hemorrhage. Angiograms were retrospectively analyzed with particular attention to the size of the AVM, venous drainage, the location of the AVM and presence of associated aneurysm or varix. These characteristics were statistically analysed in relation to occurrence of hemorrhage. Results : A single variate analysis demonstrated that small size(p=0.0003), deep venous drainage(p=0.025) and periventricular location(p<0.0001) had a strong positive correlation. Associated aneurysms and varices were not found as hemorrhagic risk factors. A multivariate analysis revealed that the size of the AVM was most significant hemorrhagic factor(p=0.0003) followed by deep venous drainage(p=0.025). AVMs with small size and deep venous drainage bled more frequently regardless of their locations. Conclusion : These data would be useful in identifying patients at higher risk for developing hemorrhage of intracranial AVMs.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.100-107
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• 2013

This study aims to improve the heat performance of motor cycle disk due to the number of holes by analyzing 6 kinds of disk models. This disk performance depends on the efficiency at emitting the heat. To raise the efficiency of heat emission, holes with circle or another configuration are made on disks to emit heat fast. The distribution of temperature, heat flux, deformation and stress are analyzed. As the number of holes on disk increases, the performance of heat emission is improved. Equivalent stress is decreased and durability is improved as the number of holes on disk increases. Though the number of holes on disk is increased, the performances of heat emission and durability do not become better. The optimal model can be found by comparing models each other through this analysis result. Through this study result, the configuration of motor cycle disk is designed with optimal heat emission and durability by comparing models.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.3
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• pp.21-27
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• 2013

This study is investigated on flow analysis according to grill configuration of radiator. The stream of flow which pass through radiator grill in car body and the contour of pressure distribution are estimated by the basis. As the magnitude of resistance force which flow affects the car body is investigated so that the power reduction can be reduced. As the pressure inside radiator grill is assessed, more efficiency can be investigated in order that the flow rate inside car body can be increased. Model 2 has the most air resistance and model 1 has the least among model 1, 2 and 3. Model 1 has the most air flow rate at inside. There are model 3 and 2 simulated according to flow rate. As the curved surface at radiator grill configuration increases in number, air flow rate becomes distributed uniformly. By considering the effect on air resistance and air flow rate at radiator grill, model 3 becomes the most effective configuration.