• Journal of the Korean Operations Research and Management Science Society
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• v.41 no.1
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• pp.127-143
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• 2016

This study applied DEA analysis to measure the relative efficiency of 35 companies that produce automobile body components. First, the input and output, the improvement target value of the calculated variables, and the reference group for benchmarking for inefficient groups to become efficient groups were established through DEA analysis. In addition, whether inefficiency was due to technical inefficiency or size was analyzed in connection with the cases of the actual companies through the measurement of scale efficiency. Second, a route for efficiency improvement was derived through DEA-Tier analysis by defining the possible group for benchmarking in actuality within the production industry of automobile body components where the primary cooperative company belonged. Third, the financial variables that generate the difference between efficient and inefficient groups were derived through logistic regression analysis. Financial strategies that determine the direction the indices should be improved to allow the inefficient group to become an efficient one were recommended. This research is expected to provide diagnostic methods for management efficiency and the direction of improvement to enhance the management efficiency of automotive parts makers by identifying the causes of the inefficiency of domestic automotive parts makers empirically. The study also provides financial strategies together with the target values of efficiency improvement for each individual company.

• Journal of the Korean institute of surface engineering
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• v.42 no.2
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• pp.79-85
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• 2009

We aimed to develop a Fe-($16{\sim}19$)Cr-($0.1{\sim}0.6$)Ti-($0.1{\sim}0.6$)Nb stainless steel for automotive exhaust parts with high corrosion resistance. The alloys with high Cr content showed high resistance to general corrosion and also localized corrosion. The increase of Ti and Nb contents resulted in a linear increase in the general corrosion resistance, while the pitting potential was improved by addition of these elements up to about 0.4 wt.%. The low-carbon Fe-17Cr-0.4Ti-0.4Nb alloy annealed at $850^{\circ}C$ and air-cooled was considered to be the optimum alloy for our purpose with the critical anodic current density of $247{\mu}A/cm^2$ in 0.05 M $H_2SO_4$ solution and the pitting potential of 310 mVSCE in 0.2 M NaCl solution.

• Korea Trade Review
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• v.44 no.6
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• pp.303-325
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• 2019

The purpose of this study is to determine optimal transportation routes through the comparison of Korean - European transportation routes of automotive parts and to suggest information that can be utilized in Korea - Europe trade activities or trade route selection by establishing multipath. This study analyzed the direct transportation cost, inventory cost, and warehouse inventory cost of the sea and TSR / TCR railroad transport based on characteristics of automotive parts logistics and multimodal transportation. Also, this study identifies the most effective transportation route from the viewpoint of total logistics cost. In addition to the economic factors, we conducted an in-depth analysis through interviews with corporate executives to identify the importance of the factors with the behavioral factors, and the reliability was further secured through interviews. Through this study, it is possible to understand various aspects of international logistics by analyzing the factors of transportation choice in terms of economic and behavioral perspectives concurrently by differentiating from existing research.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.103-116
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• 1993

Recently, engineering ceramics called as the 3 material have been concerned significantly with some excellent mechanical properties and many functions as new materials for high precision mechanical components and engineering parts for at large. Then, for designing engineering parts using engineering ceramics, bending strength value data with high reliability is more essential than any other mechanical properties. But, because of brittleness and structural characteristic, it is very hard to grind with conventional tools, and the generation of cracks and various defects of engineering ceramics parts during grinding machining process are serious problems. Thus, in present study, surface grinding experiments with various machining conditions using resin bond diamond wheels are carried out to obtain the most excellent guality of testpiece surface and optimum step of grinding process for the high efficient stock removal rate to save running time. As the results from grinding experiments and 3-points bending strength test of ground Al2O3 ceramics parts on Korean Standard, manufactured in our country and Japan, basic technology and know-how to develop the optimum grinding machining conditions and also high bending strength values with high reliability are obtained.

• Transactions of Materials Processing
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• v.29 no.5
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• pp.241-250
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• 2020

In this study, the methodology of the springback prediction of automotive parts applied 3rd generation AHSS was investigated using the response surface model analysis based on a regression model, and the meta model analysis based on a Kriging model. To design the learning data set for constructing the springback prediction models, and the experimental design was conducted at three levels for each processing variable using the definitive screening designs method. The hat-shaped member, which is the basic shape of the member parts, was selected and the springback values were measured for each processing type and processing variable using the finite element analysis. When the nonlinearity of the variables is small during the hat-shaped member forming, the response surface model and the meta model can provide the same processing parameter. However, the accuracy of the springback prediction of the meta model is better than the response surface model. Even in the case of the simple shape parts forming, the springback prediction accuracy of the meta model is better than that of the response surface model, when more variables are considered and the nonlinearity effect of the variables is large. The efficient global optimization algorithm-based Kriging is appropriate in resolving the high computational complexity optimization problems such as developing automotive parts.

• Transactions of Materials Processing
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• v.32 no.6
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• pp.311-320
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• 2023

Recently, lightweight of automotive parts has been required to solve environmental problems caused by global warming. Accordingly, research and development are proceeded on manufacturing of parts using aluminum that can replace steel for lightweight of the automotive parts. In addition, high strength aluminum can be applied to body parts in order to meet both requirements of lightening and improving crash safety of vehicle. In this study, hot blow forming of roof side rail is employed to manufacturing of the automotive parts with high strength aluminum tube. In hot blow forming, longer forming times and excessive thinning can be occurred as compared with conventional manufacturing processes. So optimization of process conditions is required to prevent excessive thinning and to uniformize thickness distribution with fast forming time. Mechanical properties of high strength aluminum are obtained from tensile test at high temperature. These properties are used for finite element(FE) analysis to investigate the effect of strain rate on thinning and thickness distribution. Variation of thickness was firstly investigated from the result of FE analysis according to tube diameter, where the shapes at cross section of roof side rail are compared with allowable dimensional tolerance. Effective tube diameter is determined when fracture and wrinkle are not occurred during hot blow forming. Also FE analysis with various pressure-time profiles is performed to investigate the their effects on thinning and thickness distribution which is quantitatively verified with thinning factor. As a results, optimal process conditions can be determined for the manufacturing of roof side rail using high strength aluminum.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.3
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• pp.1-6
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• 2012

This paper developed the chassis part as micro-alloyed steel with high toughness. The performance of micro-alloy steels are superior to similar heat treated steels. The strengthening effects of vanadium make micro-alloyed steels particularly suited for high-strength-steel applications. The disadvantages are that ductility and toughness are not as good as quenched and tempered (Q&T) steels. Precipitation hardening increases strength but may contribute to brittleness. Toughness can be improved by reducing carbon content and titanium additions. dispersed titanium nitrides (TiN) formed by titanium additions effectively prevents grain coarsening. Grain refinement increases strength but also improves toughness. For the chassis parts using high toughness micro-alloy steel, it had proven superior to a plain steel forging by static strength test and endurance test.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.5
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• pp.60-75
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• 1990

Advanced Ceramics have some excellent prosperities as the material for the mechanical component. It is, however, very difficult to grind ceramics with high efficiency because of their high strength, hardness and brittleness. In this study, various machining experiments are carried out to obtain the basic knowledge of grinding High Strength Ceramics with high efficiency and precision for the purpose of application to Automobile parts. Advanced Engineering Ceramics such as Si$_{3}$N$_{4}$, SiC, ZrO$_{2}$, $Al_{2}$O$_{3}$ are ground with diamond wheels using conventional grinding machine. Results obtained in this study provide some useful informations to attain the high efficiency grinding of Advanced Ceramics.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.79-85
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• 2009

Low temperature combustion regime for the simultaneous reduction of nitrogen oxides ($NO_x$) and paticulate matter (PM) is demonstrated in single cylinder engine at various operating parameters, such as EGR rate, injection timing, EGR temperature, amount of fuel and swirl rate. Low temperature combustion is accomplished by high exhaust gas recirculation (EGR) rate in this study. Generally, the emission of $NO_x$ almost completely disappears and PM significantly increases in the first decreasing regime of oxygen concentration but after peaking about 10~12% oxygen concentration, PM then decreases regardless of fuel injection quantity. Low temperature combustion regime was extended by low EGR temperature, high injection pressure and low amount of fuel.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.15-20
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• 2014

The stereolithography(SL) process is a type of fabrication technology which relies on photopolymerization. It has a relatively simple fabrication process and a resolution of several tens of ${\mu}m$. Recently, SL technology has been applied to various areas, such as bioengineering and MEMS devices, due to the development of advanced materials. This technologycan be divided intothe scanning(SSL) and projection (PSL) types. In this paper, in stereolithography, parts are fabricated by curing photopolymeric resins with light. The application of stereolithography can now include fabricated parts. This process, called stereolithography, can fabricate parts by taking into account theirdegrees of geometry complexity. In particular, UV-LED stereolithography can perform quite rapid fabrication in which specific cross-sections are cured upon exposure to light.