Lab Director

1994 B.S. in Mechanical Design and Production Engineering, Seoul National University, Korea (Summa Cum Laude)

1996 M.S. in Mechanical Design and Production Engineering, Seoul National University, Korea

• • Inverse heat transfer method에 의한 열전달 계수 분포의 결정 (Advisor Prof. Sooik Oh)

2001 Ph.D. in Mechanical and Aerospace Engineering, Seoul National University, Korea

• • Finite element analysis of micro-forming process by crystal plasticity considering couple stress (Advisor Prof. Sooik Oh)

2018.8 - 2019.8 Visiting Scholar, Portland State University, USA

2003.4 - 2012.8 Senior/Principal Researcher, Korea Institute of Industrial Technology, Korea

2001.9 - 2003.4 Special Researcher, Institute of Advanced Machinery and Design, Seoul National University, Korea

한국자동차공학회 생산및재료부문 회장 (Chairman of manufacturing & materials division, The Korean Society of Automotive Engineers)

한국자동차공학회 국문논문편집위원

Journal of Computational Design and Engineering, Editorial Board Member

한국소성가공학회 편집이사 (Technical director, The Korean Society for Technology of Plasticity)

한국소성가공학회 금형가공부문위원회 (Committee member of dies & molds division, The Korean Society for Technology of Plasticity)

한국소성가공학회 박판성형부문위원회 (Committee member of sheet metal forming division, The Korean Society for Technology of Plasticity)

NUMISHEET 2011 벤치마크 위원회 (Committee member of bench mark committee, NUMISHEET 2011)

TUBEHYDRO 2013 조직위원회 (Committee member of organizing committee, TUBEHYDRO 2013)

FISITA 2016 조직위원회, 생산및재료 토픽리더 (Committee member of organizing committee, FISITA 2013)

한국금형공학회 프레스금형분과 위원장

FEM-based Investigation of Intra- and Inter-Granular Deformation of Crystalline Metals during Metal Forming Process based on Crystal Plasticity. Developed a FEM-based computer program, which can be applied to predict the grain-by-grain deformation of polycrystal as well as single crystal metals. Incorporated the couple stress into the crystal plasticity formulation to describe the microstructure evolutions as well as micro forming characteristics. Various simulations of single and bi-crystal deformation showed that the developed formulation is very effective in prediction of the intra- as well as inter-granular deformation and microtexture evolution of crystalline metals. The finite element simulation results were compared with the conducted compression test of aluminum specimens composed of a few grains to validate the predictability of grain-by-grain deformation.

Development of Warm Press Forming Technology for Magnesium Alloy Sheet. Designed and fabricated the warm press forming die system for magnesium alloy sheet. Optimized the process conditions (e.g., temperature, lubricant, forming velocity, blank holding force, etc.) for mass production of magnesium alloy sheet part and product. The non-isothermal deformation behavior during the magnesium alloy sheet forming was FE analyzed for die and forming process design.

Development of Temperature and Strain-Rate Incorporated Failure Model for Magnesium Alloy Sheet Forming. Formulated the temperature and strainrate incorporated failure model based on the ductile fracture criterion. Developed a FEM failure analysis module by implementing the failure model into user subroutine of a commercial FEM program. Validated the proposed failure model by comparison with the experimental fracture behavior of magnesium alloy sheet at various temperature and strain-rate conditions.

Optimization of Multi-Stage Deep Drawing Process of Low-Formability Metal Sheet. Carried out a FEM-based optimization of manufacturing process of cup-shaped Molybdenum electrode which is used for CCFL(Cold Cathode Fluorescent Lamp) to improve the optical performance. An optimum multistage deep drawing process was obtained through numerous nonlinear FEM calculations combined with a global as well as a local optimization algorithm.

Evaluation of Heat Transfer Coefficient during Heat Treatment by Inverse Analysis. Evaluated heat transfer coefficient distributions over metal surface during heat treatment processes. For that purpose, developed a computer program based on the inverse method, which provided heat transfer coefficient from the measured temperature data, and carried out experiments that simulate water quenching and air cooling process. Heat transfer coefficient data obtained from the developed inverse analysis program using the measured temperature were proved to be a reasonable evaluation by being compared with the experimental investigations.

Development of Hot Embossing and Molding Technique for High Precision Large Area Pattern Formability. Designed and fabricated a hot embossing machine with a robust structure based on a FEM structural analysis of machine frame and parts. A hybrid mold structure for hot embossing was also designed and fabricated to improve the conformal contact during large area embossing of micro pattern structures.

FEM-based Evaluation of Residual Stress Evolution during Cure Process of Silicone Resin for High-Power LED Encapsulant. Examined residual stress evolution behavior during silicone resin cure process which is composed of chemical curing and subsequent cooling. Evaluated a cure kinetics equation to model chemical curing of silicone based on the measurement by differential scanning calorimeter. Tested various elastic modulus and chemical shrinkage as a function of the degree of cure to examine the effect on residual stress evolution.