• Journal of KSNVE
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• v.5 no.4
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• pp.503-514
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• 1995

In the case of performing experimental modal analysis(EMA) and finite- element analysis(EFA) for a whole structure of automotive body that is composed of many complex parts, a trouble may arise from the calculation time, the capacity of memory in computers and the experimental conditions, etc. In this paper, for the vibrational analysis of automotive body model, the efficient modal synthesis method by means of dividing the whole structure into two parts and performing EMA and FEA for each part is studied. In addition, the method based on Lagrange interpolation is proposed for approximating rotational degrees-of-freedom information and linking FEA with EMA. In result, by measuring translational degrees-of-freedom information of only few points and adopting only few modes, the linking method based on Lagrange interpolation turned out to be efficient and accurate in the low frequency range.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.50-59
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• 1996

The computer simulation program that calculates the transient heat load transferred to a passenger vehicle has been developed. Method for modeling mathematically various kinds of the heat load was presented and the derived equations were solved numerically. To find out the accuracy of the simulation program, the correlation of experimental and analytical results was demonstrated. By using this program, the typical characteristics about temperature distribution and instantaneous or of vehicle body color, material of glass, air-conditioning capacity, driving direction, and speed. Under a steady-state condition, the ratios of the heat load, resulting form vehicle body, glass, and interior part, were 35%, 29%, and 36%, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.31-36
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• 1997

Various methods of finite element modeling for welded part are examined and the stamping simulation of automotive body is presented by using the explicit finite element code PAM-STAMPTM. The process of stamping simulation is suggested step by step, and then the gravity, binder wrap, forming, trimming and springback of front door inner are analyzed. It shows good agreements with real product in the aspects of deformed shape and failure area. The door inner with laser-tailor welded blank is simulated, in which deformed shape, movement of welde line and formability are predicted.

• Transactions of Materials Processing
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• v.9 no.6
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• pp.624-630
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• 2000

Typical automotive opening parts, i. e. hood trunk lid and door, are made through the press operations such as drawing, trimming, flanging, and hemming. The dimensional accuracy of stamped panels is mainly dependent on the drawing operation. However, the gap between outer panels and opening parts, which is important to the appearance quality of the assembled body, is directly influenced by the flanging and hemming operation. In this study, the relation between the design parameters of the hemming operation and the defect of roll-in is shown. The effects of some design parameters on the gap are examined using CAE. furthermore, the simulated results of the hemmed part of tailgate comer are shown and discussed.

• Korean Journal of Computational Design and Engineering
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• v.16 no.5
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• pp.323-330
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• 2011

Large number of part design such as for aircraft and automotive development is preceded by functional or sectional design groups for efficiency. With the assembly development of large number of parts, interferences and gaps can be found when the parts and sub-assemblies by those design groups are to be assembled. When rainwater come into the space among parts and is not be drained sufficiently, rainwater within the structure can backflow to gaps or unexpected outlets, which may cause severe problems of part corrosion and electric shock. This research has developed a method and a program to simulate backflow of rainwater within space among parts, which can find unexpected outlets and gaps as in real situation. The developed program can not only simulate up and downstream of liquid, but also the flow with multiple channels of division and joining. The developed method can also be applied to aircraft and ship design process.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.21-29
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• 2003

Boosting of engine power by using Turbo- or Super-charger is a solution to comply with $CO_2$-regulation in Europe. Turbo-charger is now playing a major role in the field of charging system thank to its technical advantages such as no demand of operation power from engine. A mechanically driven Super-charger, however, is now popular due to quick speed response to change of the driving mode-high engine torque even at low engine speed. Since Super-charger needs operation power from engine, it is difficult to improve its relatively higher fuel consumption than that of Turbo-charger. This negative point is still an obstacle to the wide use of Super-charger. This study aims to develop power control concept to achieve the minimization of operation power when it is not necessary to charge at idling or part load driving condition. A screw type Super-charger was modified in design partially and adapted an internal bypass valve and a bypass tube to control charging pressure at part load. The various control concepts show a possibility to reduce operation power of Super-charger and result in improvement of fuel consumption.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.85-94
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• 2014

Tolerance accumulation has serious effect on the performance of an assembled body. This paper proposes the method which analyzes tolerance accumulation using Monte Carlo Simulation. This method can predict tolerance distribution of fully assembled body using the dimensional tolerance distribution of each part to be assembled. In this analysis, it is assumed that the tolerance of each part has the nominal distribution or uniform distribution. This analysis method is applied to ECV(External Control Valve), and the accumulated tolerance of the fully assembled ECV is obtained from the analysis. The results show that initial tolerance given to each part do not meet the design requirement of ECV. Hence, the tolerances of each part are modified and the additional analysis with the modified tolerances yields the results which satisfy the design requirements of ECV.

• Transactions of Materials Processing
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• v.19 no.1
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• pp.32-37
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• 2010

Hydroforming has attracted a great deal of attention in the manufacturing industries for vehicles and transportation systems. Hydroforming technology contributes to weight reduction, increased strength, improved quality and reduced tooling cost. Hydroformed automotive parts used as structure components in vehichle body frame often have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. For a given flange shape, a parting plane for the dies is established relative to which the various surfaces of the flange shape, in cross section, have no significant reverse curvature. In this study, hydroforming process for flange forming was proposed. FE analysis to form flanged circular shape and flanged rectangular shape was preformed with Dynaform 5.5. To accomplish successful hydroforming process design, thorough investigation on proper combination of process parameters such as tool geometry and hydraulic pressure has been performed and optimized. The results show that flanged automotive parts can be successfully produced with tube hydroforming.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.109-118
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• 2012

Large number of part design for aircraft and automobile is preceded by functional or sectional design groups for efficiency. However, interferences and gaps can be found when the parts and sub-assemblies by those design groups are to be assembled. These interferences and gaps cause design changes and additional repair processes. While interference problem has been resolved by digital mockup and concurrent engineering methodology, gap problem has been covered by temporary treatment of filling gap with sealant. This kind of fast fix causes fatal problem of leakage when the gap is too big for filling or the treatment gets old. With this research, we have developed a program to find the gap automatically among parts of assembly so that users can find them to correct their design before manufacturing stage. By using decomposition model representation method, the developed program can search the gap among complex car body parts to be visualized with volumetric information. It can also define the boundary between the gap and exterior empty space automatically. Though we have proved the efficiency of the developed program by applying to automobile assembly, application of the program is not limited to car body only, but also can be extended to aircraft and ship design of large number of parts.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.364-370
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• 2011

Currently, there are two main issues regarding the development of core technologies in the automotive industry: the development of environmentally friendly vehicles and securing a high level of safety in the event of an accident. As part of the efforts to address these issues, research into alternative materials and new car body manufacturing and assembly technologies is necessary, and this has been carried out mainly by the automotive industries. Large press molds for producing car body parts are made of cast iron. With the increase of automobile production and various changes of design, the press forming process of car body parts has become more difficult. In the case of large press molds, high hardness and abrasive resistance are needed. To overcome these problems, we attempted to develop a combined heat treatment process consisting of local laser heat treatment followed by plasma nitriding, and evaluated the characteristics of the proposed heat treatment method. From the results of the experiments, it has been shown that the maximum surface hardness is 864 Hv by the laser heat treatment, 953 Hv by the plasma nitriding, and 1,094 Hv by the combined heat treatment. It is anticipated that the suggested combined heat treatment can be used to evaluate the durability of press mold.