• 한국자동차공학회논문집
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• 제24권1호
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• pp.53-58
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• 2016

Modeling of engine coolant temperature was conducted for a series hybrid powertrain system. The purpose of this modeling was a simplification of complex heat transfer process inside a engine cooling system in order to apply it to the vehicle powertrain simulation software. A basic modeling concept is based on the energy conservation equation within engine coolant circuit and are composed of heat rejection from engine to coolant, convection heat transfer from an engine surface and a radiator to ambient air. At the final stage, the coolant temperature was summarized as a simple differential equation. Unknown heat transfer coefficients and heat rejection term were defined by theoretical and experimental methods. The calculation result from this modeling showed a reasonable prediction by comparison with the experimental data.

• 한국정밀공학회지
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• 제30권10호
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• pp.1111-1117
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• 2013

In this paper, the shape accuracy of the stamped hat-type product is quantified and analyzed with ultra high strength steel (UHSS) sheets. The shape of the hat-type product is designed in order to simplify the geometry of the side sill and the stamping methodology is proposed in order to verify the effect of the stamping procedure on the springback amount. Experiments and finite element analyses are conducted with four kinds of the forming sequences. The springback amounts are measured and compared according to the forming procedure with the embossing shape. Experimental result in company with analysis one illustrate that the springback amount is reduced with embossing in the padding operation. They also fully demonstrates the proposed forming procedure and the analysis method can be effectively applied to the process design for producing parts with ultra high strength steel.

• 동력기계공학회지
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• 제18권6호
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• pp.34-39
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• 2014

In this study, the structural analysis and the modal analysis are conducted to investigate the stress level, the deformation characteristics and the natural modes of the casing of a planetary gear reducer for a 800kW grade pulverizer mill. The casing is subjected to the load, 2800 kN, from the lump coals in the pulverizing process. Because of the symmetry, the half portion of the reducer casing is modeled for the stress analysis. But the full model is used to find out the eigenvalues and natural modes for the modal analysis. The contact conditions are applied between the thrust pad bearing and the adjacent contacting parts. The results shows that the casing structure has the sufficient strength and stiffness to support the load under consideration. ANSYS version 15 is employed to perform the numerical study.

• 산업경영시스템학회지
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• 제42권4호
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• pp.31-38
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• 2019

The purpose of this study is to provide the priority of the front-loading factors in the design stage of the automotive parts development process in order to efficiently and effectively respond to the demands of the car maker (customer). Front-loading is defined as a strategy in order to improve development performance by shifting the identification and solving of design problems to earlier phases of a product development process. Two approaches of the front-loading are project-to-project knowledge transfer and rapid problem solving. For the study, a survey was conducted on the R&D department in the automobile parts company and analyzed by AHP (Analytic Hierarchy Process) method. The result of the survey shows the cost savings is the highest weight in terms of front-loading effect and in terms of front-loading factors, it gives priorities as "the problems of past project" first, "Design Review" second, "CAE (Computer Aided Engineering)" third, "FMEA (Failure Mode and Effects Analysis)" fourth, "benchmarking" and SR (Sourcing of Requirements). The results of the study will be helpful to provide practical value for improving product design of component development.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권1호
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• pp.79-85
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• 2017

In this paper, several optimizations are proposed to enhance the quality of lane detection algorithms in automotive applications. Considering the diagonal directions of lanes, the proposed limited Hough transform newly introduces image-splitting and angle-limiting schemes that relax the number of possible angles at the line voting process. In addition, unnecessary edges along the horizontal and vertical directions are pre-defined and removed during the edge detection procedures, increasing the detecting accuracy remarkably. Simulation results shows that the proposed lane recognition algorithm achieves an accuracy of more than 90% and a computing speed of 92 frame/sec, which are superior to the results from the previous algorithms.

• The Korean Journal of Ceramics
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• 제5권1호
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• pp.50-54
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• 1999

$(Pb_xLa_{1-x}) (Zr_yTi_{1-y})O_3$ (PLZT) thin films with electrooptic effect are promising for the optical application such as display or light shutter. However, it is difficult to use inexpensive and transparent glass substrates because the conventional process for preparation of PLZT requires temperatures above $600^{\circ}C$. In order to deposit a perovskite PLZT thin films at low processing temperatures through alkoxide route, we have offered several seeding processes which reduce the activation energy for crystallization. In this study, we optimized the stacking structure of multilayered PLZT for obtaining single phase perovskite at lower temperatures. As a result, ferroelectric PLZT thin films with different compositions were successfully prepared at a temperature as low at $500^{\circ}C$.

• 한국주조공학회지
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• 제24권3호
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• pp.153-158
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• 2004

본 연구에서는 기존 고압주조법의 해결과제인 고속충진 시 혼입되는 금형 cavity 내부의 유해 gas에 의한 gas porosity를 제어하기 위한 고속 사출 전 진공시스템 설계와 응고과정에서 발생되는 응고수축에 의한 shrinkage를 효과적으로 제어하기 위한 국부가압 스퀴즈의 조합시스템의 설계로 최적의 기계적 성질을 갖는 부품을 제조할 수 있는 공법을 개발하였다. 또한 개발된 신공법으로 자동차용 고내마모성 요구부품인 Reaction Shaft Support에 기존의 주철제를 대체하는 Al-15wt.%Si 과공정합금을 적용하여 시제품을 제조하였으며, 기존의 공법과 비교한 결과, 내부 porosity가 없는 미세하고 균일한 공정 및 초정 Si의 미세조직을 얻을 수 있었고, 기계적 특성평가에서도 매우 우수한 결과를 얻을 수 있었다.

• Journal of Welding and Joining
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• 제27권6호
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• pp.9-16
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• 2009

In this paper, the coaxial monitoring system to capture image of weld pool was developed in laser-arc hybrid welding. In order to obtain the reliable image, green laser was used as a illumination system and measuring components such as band pass filter, ND (Neutral Density) filter and shutter speed was designed and optimized. Using this monitoring system, weld pool images were captured according to laser power, welding speed, welding current and interspace between laser and arc through the experiment. ANOVA (Analysis of Variation) was carried out to identify the influence of process variables on bead widths extracted from captured images of monitoring system. Welding speed and current were major factor to affect weld pool.

• 대한금속재료학회지
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• 제49권6호
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• pp.448-453
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• 2011

Pre-aging heat treatment after solution heat treatment (SHT) of Al-0.4 wt%Mg-1.2 wt%Si-0.1 wt%Mn alloy sheets for auto-bodies was carried out to investigate the effect of pre-aging and its conditions on the bake-hardening response. Mechanical properties were evaluated by a tensile and Vickers hardness test. Microstructural observation was also performed using a transmission electron microscope (TEM). It was revealed that pre-aging treatments play a great role in the bake-hardening response. In addition, it was found that the sphere-shaped nanosized clusters that can directly transit to the needle-shaped ${\beta}$" phase during the paint-bake process, not being dissolved into the matrix, are formed at 343 K. The result, reveals that the dominant factor of the bake-hardening response is the pre-aging temperature rather than the pre-aging time.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.148-156
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• 2013

Since the demand for new military vehicle to fulfill the necessary conditions such as multi-purpose, high-mobility, and survivability has raised continuously from the army, the prototype of a Korean light tactical vehicle was developed to meet these requirements using our own technology. In particular, the new tactical vehicle was equipped with a double wishbone independent suspension to improve ride and handling and maximize off-road driving performance. In this paper, a comprehensive virtual durability process to evaluate the service life of the prototype is presented. A reliability of the trimmed body model based on CATIA data was verified by comparison result between mode analysis and modal test. The dynamic model was constructed using ADAMS/Car, and then the weight distribution and lateral slope driving performance of it were compared with the results of static weight and lateral slope tests. The validity of the VTL(Virtual Test Lab) was checked with test results from the 3-inch spaced impact road. The durability performances of trimmed body and suspension components were evaluated through MSM(Modal Superposition Method) fatigue analysis. It is shown that the virtual durability process could be a helpful tool to find out the weak areas and improve their structures in developing new military vehicle.