• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.335-336
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• 2010

본 논문에서는 Plug-in Hybrid Electric Vehicles (PHEVs)의 배터리 충전을 위해 필요한 추가적인 충전기 없이, 구동모터의 인덕턴스와 구동 드라이버인 3상 인버터를 이용하는 배터리 충전 기법을 소개한다. 모터의 인덕턴스를 승압용 에너지 저장장치로 사용하고 인버터의 스위칭 제어를 통해 부스트 컨버터로 사용하여 별도의 충전기를 제거함으로써 충전장치의 크기 및 단가를 저감할 수 있다. 상세한 유형별 이론적 분석과 시뮬레이션 결과를 제시하여 제안된 충전기법의 타당성을 검증한다.

• International Journal of Korean Welding Society
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• v.2 no.2
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• pp.47-50
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• 2002

Because of the environmental problems, automotive companies are trying to reduce the weight of car body. Therefore, TRIP(TRansformation Induced Plasticity) steels, which have high strength and ductility have been developed. Welding process is a complex process; therefore deciding the optimal welding conditions on the basis of experimental data is an effective method. However, trial-and-error method to decide the optimal conditions requires too many experiments. To overcome these problems, response surface methodology was used. Response surface methodology is a collection of mathematical and statistical techniques that are used in the modeling and analysis of problems in which a response of interest is influenced by several variables and the objective is to optimize this response. This method was applied to the resistance spot welding process of the TRIP steel to optimize the welding parameters.

• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.45-50
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• 2003

Welding using lasers can be mass-produced in high speed. In the laser welding, performing real-time monitoring system of the welding quality is very important in enhancing the efficiency of welding. In this study, the plasma and molten metal which are generated during laser welding were measured using the UV sensor and IR sensors. The results of laser welding were classified into five categories such as optimal heat input, little low heat input, low heat input, partial joining due to gap mismatch, and nozzle deviation. Also, a system was formulated which uses the measured signals with a fuzzy pattern recognition method which is used to perform real-time evaluation of the welding quality and the defects which can occur in laser welding.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.118-123
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• 1999

The recycle of the polycarbonate(PC)/acrylonitrile-butadiene-styrene(ABS) separated from the instrument panel (In-Panel) of the automotive was investigated. The small amount of polyurethane(PU) foam contained in the separated PC/ABS decreased the mechanical properties of the recycled PC/ABS. However, it is found that the PU foam formed the dispered phase of small particles at high temperature ($260^{\circ}C$) under high shear of the twin extruder, whereas it formed the big particles at low extrusion temperature ($220^{\circ}C$). The mechanical properties of the recycled PC/ABS extruded at high temperature was better than those at low temperature, which enabled the recycled PC/ABS seperated from In-Panel to be applied to the radiator grille without the addition of the compatibilizers or virgin PC/ABS. This was ascribed to the smaller particle sizes of the PU foam formed at high extrusion temperature under high shear.

• Journal of Welding and Joining
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• v.30 no.2
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• pp.59-64
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• 2012

Welding is an essential process in the automotive industry. Most welding processes that are used for auto body are spot welding and $CO_2$ welding are used in a small part. In production field, $CO_2$ welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in $CO_2$ welding process frequently. But $CO_2$ welding process should be used at robot interference parts and closed parts where spot welding couldn't. Because of the 0.65mm ~ 2.0mm thickness steel sheet were used in the automotive industry, poor quality of welding area such as burn through and under fill were happened frequently in $CO_2$ process. In this paper, we will study about the penetration depth which gives a huge impact on burn through changing a degree of base metal, welding position and torch angle. Voltage, current and welding speed were fixed but degree of base metal, welding position and torch angle were changed. And Cold- Rolled(CR) steel sheet was used. Penetration depth was analysed by multiple regression analysis to derive approximate calculations. And reliability of approximate calculations were confirmed through additional experiments. As the results of this research, we confirmed the effect of torch and plate angle to bead shape. And we present a possibility that can simulate more accurate to weld geometry, as deduced the verification equations that has tolerance of less than 21.69%.

• Journal of the Korean Ceramic Society
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• v.41 no.10 s.269
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• pp.777-782
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• 2004

In this research, $5\times5cm^2$ unit cells were fabricated via liquid condensation process and uniaxial pressing followed by the screen printing of electrolyte and cathode layer. The SOFC stack was assembled with unit cells, gasket-type sealant and metal interconnect. The stack was designed to have a single column with internal-manifold and cross-flow type gas-channels. The SOFC stack produced 15 W, which is $50\%$ of the maximum power being expected from the maximum power density of the unit cell. Controlling factors for the proper operation of the SOFC stack and other designing factors of stack manifold and gas channels were discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.491-498
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• 2010

Humidification of PEM fuel cells is necessary for enhancing their performance and lifetime. In this study, a humidification system was designed and tested; the system includes an air-supply tube (inner diameter: 75 mm) through which a nozzle can be directly inserted and a cyclonic separator for the removal of water droplets. Three types of nozzles were employed to study the influence of injection pressure, air flow rate, and spray direction on the humidification performance. To evaluate the humidification performance, the concept of humidification efficiency was defined. In the absence of an external heat source, latent heat for evaporation will be supplied by the own enthalpies of water and air. Thus, the amount of water sprayed from the nozzle is the most critical factor affecting the humidification efficiency. Water droplets were efficiently removed by a cyclonic separator, but re-entrainment occurred at high air flow rates. The absolute humidity and humidification efficiency were $21.29\;kJ/kg_{da}$ and 86.57%, respectively, under the following conditions: nozzle type PJ24; spray direction angle $90^{\circ}$; injection pressure 1200 kPa; air flow rate 6000 Nlpm.

• Elastomers and Composites
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• v.42 no.4
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• pp.249-258
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• 2007

In this study, the EPDM powder which was surface activated by high temperature and shear pulverization process was prepared and the mechanical properties and odor material analysis were investigated. Analysis for particle size and size distribution of waste of the EPDM powder has been performed. The waste EPDMs used in this study were 4 types of solid, sponge, solid+sponge, and solid+metal. According to the results, the solid type showed the smallest particle size among the 4 types of EPDM powder. Effective surface devulcanization of EPDM powder could be obtained by the addition of the reclaiming agent. The dicumyl peroxide was considered as the best crosslink agent for dynamic vulcanization when the surface activated EPDM powder was blended with polyolefin in order to make TPE. Also, the optimum amounts of DCP was 6 phr in terms of surface crosslink reaction and mechanical properties of EPDM powder. The processes of water adsorption and rose oil addition were employed to remove the odor of EPDM powder caused by reclaiming agent. The GC/MS was used to analyze the odor compounds.

• Elastomers and Composites
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• v.40 no.2
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• pp.93-103
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• 2005

In this study, surface treatment of the elastomeric matrix was investigated to develop a substituting material for steel dynamic damper of automobile. The key technology is to get ultra high density elastomeric compound in order to substitute steel dynamic damper. The optimum matrix material(chloroprene rubber) and filler(metal powder) were selected for this. The several properties of elastomeric compound were examined. According to the results, the $t_{s2}$ of filled elastomeric compound was decreased with increasing the filler loading whereas the $t_{90}$ was increased. Also, tensile strength and rebound resilience were decreased with filler loading. To solve the problem of high filler loading, the photo grafting technique was employed on elastomeric matrix. The degree of grafting was determined by FTIR-ATR. Also, the filler surface was modified by chemical etching and the surface morphology was examine by SEM. After chemical treatment of filler, the particle size analyzer was used to examined the particle size, size distribution, and morphology of the modified filler.

• Journal of the Korea Society for Simulation
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• v.29 no.4
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• pp.55-64
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• 2020

Since the European Union-South Korea Free Trade Agreement entered into force in 2011, the Korean automobile market has grown rapidly, resulting in intensifying competition among companies in the market. European automakers gained price competitiveness, which intensified competition with Korean automakers. In such a situation, various studies on the Korean automobile market have been conducted, but studies such as market influencing factor analysis and consumer analysis have mainly been conducted, and there is no research on the analysis of competitive dynamics in the market. In this study, the competitive dynamics between Hyundai Motors, Kia Motors, Mercedes-Benz, and BMW, which are major automakers in the Korean automobile market, are analyzed. The competitive relationship between major automakers are modeled using the Lotka-Volterra (LV) model and the competitive dynamics over time are analyzed by applying the Moving Window. In order to explain the competitive dynamics effectively, we analyze it by subdividing it based on various influencing factors.