• Proceedings of the KSR Conference
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• 2008.11b
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• pp.93-99
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• 2008

The SeoulMerto, operating subway line No.$1{\sim}4$, was constructed in the metropolitan Seoul with the highest population. When it was built, the design was challenged to sharp curved tracks considering the protection of buildings, cultural assets, the connection to ground roads and rivers as well as to elevated railway in some parts. Lots of residential apartments and business complex have gradually increased in the area around subway stations and railway lines according to the urban development. Consequently, Requirements of better quality of life and comfortable environment caused the citizen complain for the noise. It has become one of serious social issues. In this paper, Noise level was analyzed using noise map measured in the running train of all routes. The analysis on the noise level was conducted according to railway type, track components type, seasonal type, retirement degree of the vehicle and subway station. Especially, Noise characteristics were analyzed by noise level data measured in the inside and outside of the train with geometry types of the concrete track. This study will contribute fundamental data for the "The Development of Sound-Absorbing Block on Concrete Track" promoted on The National R&D Project.

• Safety and Health at Work
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• v.1 no.1
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• pp.43-50
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• 2010

Objectives: The objective of this study was to investigate the effect of chain installation condition on stress distribution that could eventually cause disastrous failure from sudden deformation and geometric rupture. Methods: Fractographic method used for the failed chain indicates that over-stress was considered as the root cause of failure. 3D modeling and finite element analysis for the chain, used in a crane hook, were performed with a three-dimensional interactive application program, CATIA, commercial finite element analysis and computational fluid dynamic software, ANSYS. Results: The results showed that the state of stress was changed depending on the initial position of the chain that was installed in the hook. Especially, the magnitude of the stress was strongly affected by the bending forces, which are 2.5 times greater (under the simulation condition currently investigated) than that from the plain tensile load. Also, it was noted that the change of load state is strongly related to the failure of parts. The chain can hold an ultimate load of about 8 tons with only the tensile load acting on it. Conclusion: The conclusions of this research clearly showed that a reduction of the loss from similar incidents can be achieved when an operator properly handles the installation of the chain.

• Journal of ILASS-Korea
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• v.26 no.3
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• pp.135-141
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• 2021

High-efficient HEV Engine cooling systems reflects variable coolant temperature because it can decrease the hydrodynamic frictional losses of lubricated engine parts in light duty conditions. In order to safely raise the operating temperature of passenger cars to a constant higher level, and thus optimize combustion and all accompanying factors, a new thermostat technology was developed : the electronically map-controlled thermostat. In this work, various crystalline plastics such as polyphthalamide (PPA) and polyphenylenesulfide (PPS) mixed with various glass fiber amounts were introduced into plastic fittings of automotive electronic controlled thermostat for the purpose of suppressing influx of coolant into the element and undesirable opening during hot soaking. Skirt was installed around element frame of automotive electronic controlled thermostat for improving thermal sensitivity in terms of response time, hysteresis and melting temperature. To validate the effectiveness and optimum shape of skirt, thermal sensitivity test and three-dimensional CFD simulation have been performed. As a consequence, important improvement in thermal sensitivity with less than 3℃ of maximum coolant temperature between opening and engine inlet was obtained.

• Journal of Energy Engineering
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• v.27 no.4
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• pp.92-97
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• 2018

This study deals with the numerical analysis for hood development to improve the cooling effect of the engine related components in engine room. Reducing the component temperature in engine room caused by a sudden temperature deviation can minimize the durability degradation of components. Therefore, in this study, numerical analysis for the development of the hood in engine room was carried out in four parts such as generator, battery, ECU and power steel oil which are relatively easy to control temperature among the main components in engine room. In order to verify the numerical analysis, experiments were conducted under the same conditions as those assumed in the numerical analysis.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.513-518
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• 2019

The non-destructive testing equipment using an eddy current was developed to check for defect in the vehicle transmission component. A defect master sample was made to test all types of defects that occur in the component and also an eddy current detector was manufactured and used to test and detect all kinds of defects. In addition, testing was held against the actual defective items to investigate the cause and type of defects, and a comparative study was conducted based on results from the examination. The software system of the eddy current detector was developed so that even a non-specialist can make assessment of detect in the component from the test results displayed on the monitor.

• Transactions of Materials Processing
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• v.28 no.5
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• pp.266-274
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• 2019

Metal sealing is used to connecting the parts between valves and fuel pipes for a FCEV which utilizes hydrogen gas of 700 bar. Instead of general carbon steel, stainless steel is the primary material used to manufacture fuel pipes due to hydrogen embrittlement. The shape of deformation between metals is an important factor on the air-tightness of the metal to metal contact. Since the stainless steel pipe is hardened using the plastic forming during the tip shaping stage, this work hardening could have an effect on the deformed shape and characteristics of contact surfaces in fastening of pipes. In this paper, the deformation history of the pipe model was considered in order to analyze the hydrogen-tightness on the metal sealing part. The contact distance and the forward displacement for fastening were compared using experimental results and the simulation results. The simulation of the effect of material change on the fitting body demonstrated that the hardness or the strength of the formed tip of the pipe was designed to a proper valued level since the characteristics of the contact surface was exhibited better when the strength of the pipe was lower than that of the fitting body.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.11
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• pp.102-108
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• 2020

The demand for lightweight materials and high-strength steel has rapidly increased to help reduce the weight of a vehicle body; it improves the fuel efficiency of automobiles and provides passenger safety. Additionally, as the material becomes thinner, the demand for its resistance against corrosion becomes higher. Hence, the application of the surface-treated steel sheet has surged rapidly. In this study, a weld bonding experiment using a delta spot welding machine is performed on a thin sheet of a different material (Al6061-T6/GA440). The thickness of the material was kept at 1 mm to reduce the weight of the automobile body parts. Additionally, the purpose of this study is to control the heat input by applying the welding conditions of a multi-stage pressure pattern to improve corrosion resistance shear strength. The analysis of nugget diameter measurement, shear tensile test, and salt spray test was performed to achieve the aim.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.56-61
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• 2020

Fuel economy has always been a major issue in the automobile industry, especially owing to the associated environmental concerns. It is widely known that only 5-20% of the energy generated by automobiles running on internal combustion engine engines is used as power, while the rest is consumed because of friction between components. The main components of the reciprocating piston type compressor used in vehicles, such as the shaft, swash plate, piston, and cylinder, cause severe energy loss owing to frictional contact between each other. The wear contact between the main shaft and the other components is particularly severe. Most quality issues arise owing to the sticking phenomenon that occurs between these parts. In this study, a coating solution to reduce friction is prepared by mixing adhesive solid lubricant, organic binder-polyadimide, inorganic binder (Binder), and graphite in four different ratios, and the best combination is determined.

• Korean Journal of Metals and Materials
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• v.46 no.11
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• pp.713-724
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• 2008

The need to lower the weights of automotive vehicle and to improve the safety of cars has resulted in the development of high strength steels such as TRIP(Transformation Induced Plasticity) and DP (Dual Phase) steel. It is well known that the higher strength of steel shows the poorer press formability. Among the high strength steels, DP steel shows several good characteristics such as low yield ratio, high initial n value, high elongation, high bake hardenability and anti-aging property. However, there's a certain limit in application of DP steels to the automotive panel parts because their poor deep drawbility caused by martensite. In this study, the effect of alloying elements on the deep drawability and recrystallization texture in TS 440MPa grade DP steel with 0.015~0.02% carbon has been investigated on the base of SEM, TEM, XRD and EBSD analysis.

• Tribology and Lubricants
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• v.37 no.3
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• pp.112-116
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• 2021

Appropriate friction model usage is important for impact analysis because the relative motions between parts that are in contact for very short durations can vary greatly depending on the friction model. Vehicle seat components that have significant effects on impact analysis are also considered. This paper presents an experimental investigation of various material contact pairs to obtain the friction parameters of the Benson exponential friction model for impact simulation. The Coulomb friction model has limitations for impact analysis because of singularity at zero velocity. Metal/nonmetal materials are prepared, and friction tests are conducted for various sliding speeds, loads, and lubrication conditions. The obtained data are used in the friction model to implement finite element analysis. The parameters of the friction model are obtained by the curve-fitting method. The experimental results show that the friction coefficient with metal/nonmetal contact pairs is stable regardless of the working conditions. The friction model used in this study can also be applied for finite element analysis of the crash conditions, where the friction changes abruptly at the contact interface; the obtained friction parameters are also expected to be more accurate with more precise tests under different working conditions. These results can help improve the accuracy of the finite element analysis.