• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.167-178
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• 2017

The steering wheel of a vehicle has a typical characteristic of automatically returning to its neutral state when the driver releases it. Steering returnability originated from the tire forces and kingpin moments. It is proportional to the reaction torque that is generated through the rack and column, which are dependent on suspension and steering geometry. It is also important to accurately predict and design it because steering returnability is related to steering performance. In this study, a detailed multibody dynamics model of a vehicle was designed by using ADAMS/Car and simulated for steering returnability. In addition, a tolerance analysis of the chassis system in terms of part dimension and properties has been performed in order to minimize the design parameters. The sensitivity of the selected design parameters was then analyzed via Design of Experiments(DOE). As a result, we were able to obtain the main parameters through a contribution analysis. It can be used to predict steering returnability and improve its performance, which is represented by the angle of restoration and laterality.

• Computers and Concrete
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• v.12 no.5
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• pp.651-668
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• 2013

Concrete structures need repairing due to various reasons such as deteriorative effects, overloading, poor quality of workmanship and design failures. Cement based repair mortars are the most widely used solutions for concrete repair applications. Various factors may affect the bond strength between concrete substrate and repair mortars. In this paper, the effects of polymer additives, strength of the concrete substrate, surface roughness, surface wetness and aging on the bond between concrete substrate and repair mortar has been investigated. Full factorial experimental design is employed to investigate the main and interaction effects of these factors on the bond strength. Analysis of variance (ANOVA) under design of experiments (DOE) in Minitab 14 Statistical Software is used for the analysis. Results showed that the interaction bond strength is higher when the application surface is wet and strength of the concrete substrate is comparatively high. According to the results obtained from the analysis, the most effective repair mortar additive in terms of bonding efficiency was styrene butadiene rubber (SBR) within the investigated polymers and test conditions. This bonding ability improvement can be attributed to the self-flowing ability, high flexural strength and comparatively low air content of SBR modified repair mortars. On the other hand, styrene acrylate rubber (SAR) modified mortars was found incompatible with the concrete substrate.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.33-44
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• 2006

As many scientific phenomena are now investigated using complex computer models, the effective use of Kriging on physical problems has been expanded to provide global approximations for optimization problems. This paper is focused on the two types of strategies to improve efficiency and accuracy of approximate optimization models using Kriging. These methods are performed by the stochastic process, stochastic-localization method(SLM), as the criterion to move the local domains and the design of experiments(DOE), the classical design and space-filling design. The proposed methodology is applied to the designs of 3-bar truss, Sandgren's pressure vessel, and honeycomb upper platform of a satellite structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.89-90
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• 2006

The bipolar plate is a major component of the PEM fuel cell stack, which takes a large portion of stack cost. In this study, as alternative materials fur bipolar plate of PEM fuel cells, graphite composites were fabricated by compression molding. Graphite particles mixed with epoxy resin were used as the main substance to provide electric conductivity. Flow channels were fabricated by compression molding, and design of experiments (DOE) was applied to the tests to evaluate moldability. Results showed that land width and channel depth were two significant factors for moldability, and channel width had little influence on the moldability.

• Journal of Korean Society for Quality Management
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• v.26 no.2
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• pp.106-117
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• 1998

The following study has been undertaken to build QIP (Quality Improvement Process) of an inner-layer process in a PCB (Printed Circuit Board) manufacturing plant. The objective of the study is stabilization and optimization of the process through quality improvement. To do that, defective factors in process are gathered by the cause and effect analysis and classified by PFD (Process Flow Diagram), key factors are found out by PFMECA (Process Failure Mode and Effect Criticalty Analisis), DOE(Design of Experiments) is a, pp.ied to those key factors to optimize the process, SPC (Statistical Process Control) chart is used to maintain the optimal conditions of the process and to improve quality continuously, and a quality management system is developed to improve quality mind and quality system for the PCB jmanufacturing plant. Overall, QIP is established to improve quality for the PCB manufacturing plant in the study.

• The KSFM Journal of Fluid Machinery
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• v.14 no.4
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• pp.45-51
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• 2011

The kimchi refrigerator is the electronic home appliance which is used for the maturing and a custody of the kimchi. In this paper, performance improvement of fan and duct system for kimchi refrigerator has been studied by using a commercial CFD code. In order to achieve a improved fan performance, three-dimensional computational fluid dynamics and the Design of Experiments method have been applied. Additionally, to know the optimized duct inlet shape with the optimized fan, the overall performances were calculated with various duct inlet shapes. The final fan and duct system for kimchi refrigerator showed improved performance in efficiency and total head compared with the existing model.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.125-128
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• 2009

LED칩 (발광 피크: 405nm)과 4 종의 형광체 (Blue, Green, OrangeRed, Red)를 이용하여 D65 표준광원r과 유사한 발광 스펙트럼을 가지는 광원을 제작하였다. 실험계획법을 활용하여 형광체간에 교호작용과 농도 변화에 따른 스펙트럼의 형상 변화 경향을 파악할 수 있었으며, 이들 결과를 실험계획법에 의해 최적화함으로서 D65 표준광원과 유사한 스펙트럼을 가지는 광원을 제작할 수 있었다.

• The KSFM Journal of Fluid Machinery
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• v.16 no.1
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• pp.24-31
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• 2013

The motion of living organisms such as birds, fishes, and insects, has been analyzed for the purpose of the design of MAV(Micro Air Vehicle) and NAV(Nano Air Vehicle). In this research, natural motion was considered to be applied to the determination of the geometry and motion of AUV(Autonomous Underwater Vehicle). The flapping motion of a number of hydrofoil shapes in AUV was studied, and at the same time, the optimization of the hydrofoil shape and flapping motion was executed that allow the highest thrust and efficiency. The harmonic motion of plunging and pitching of NACA 4 digit series models, was used for the numerical analysis. The meta model was made by using the kriging method in Optimization method and the experimental points of 49 were extracted for the OA(Orthogonal array) in DOE(Design of experiments). Parametric study using this experimental points was conducted and the results were applied to MGA(Micro Genetic Algorithm). The flow simulation model was validated to be an appropriate tool by comparing with experimental data and the optimized shape and motion of AUV was turned out to produce highest thrust and efficiency.

• Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.63-70
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• 2016

Deep drawing is a forming process in which a blank of sheet metal is radially drawn into a forming die by the mechanical action of a punch and converted to required shape. Deep drawing involves complex material flow conditions and force distributions. Radial drawing stresses and tangential compressive stresses are induced in flange region due to the material retention property. These compressive stresses result in wrinkling phenomenon in flange region. Normally blank holder is applied for restricting wrinkles. Tensile stresses in radial direction initiate thinning in the wall region of cup. The thinning results into cracking or fracture. The finite element method is widely applied worldwide to simulate the deep drawing process. For real-life simulations of deep drawing process an accurate numerical model, as well as an accurate description of material behavior and contact conditions, is necessary. The finite element method is a powerful tool to predict material thinning deformations before prototypes are made. The proposed innovative methodology combines two techniques for prediction and optimization of thinning in automotive sealing cover. Taguchi design of experiments and analysis of variance has been applied to analyze the influencing process parameters on Thinning. Mathematical relations have been developed to correlate input process parameters and Thinning. Optimization problem has been formulated for thinning and Genetic Algorithm has been applied for optimization. Experimental validation of results proves the applicability of newly proposed approach. The optimized component when manufactured is observed to be safe, no thinning or fracture is observed.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.370-376
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• 2011

Recently, the application range of plastic gears is widely expanding by the development of engineering plastics with good mechanical properties. Plastic gears have excellent performances such as light weight, water resistance and vibration absorbing ability for metallic gears. In this study, the optimization of injection molding process was done for the large disk type plastic gears of auto phoropter. Design Of Experiment (Taguchi method) was adopted to find a tendency of molding conditions that influence the flatness of disk type gear. Four main factors for molding conditions were selected based on injection temperature, filling time, packing pressure and mold temperature. Also, Filling, packing and cooling analyses were carried out to evaluate Z directional deflection of large disk type gear by using the simulation software (Moldflow) based on the DOE. From the results, it was found that the injection temperature and packing pressure are the most sensitive parameters for the Z directional deflection of large disk type gears.