Changwoo Lee
Pohang University of Science and Technology
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Publication
Featured researches published by Changwoo Lee.
Journal of Micromechanics and Microengineering | 2007
Duk-Hyun Choi; Sangmin Lee; Changwoo Lee; Pyung-Soo Lee; Jung-Hyun Lee; Kun-Hong Lee; Hyunchul Park; Woonbong Hwang
Mechanical properties of nanohoneycomb structures are measured for varying porosity (or pore diameter) of the nanohoneycomb structure. The indentation modulus and hardness in the pore direction (or thickness direction) are obtained from indentation tests using a nano-indenter. The bending modulus of the nanohoneycomb structures in the vertical direction relative to the pore (generally along the beam length) is determined from bending tests in AFM. To determine the bending modulus of the nanohoneycomb structures, the area moment of inertia of the nanohoneycomb structure is determined according to the arrangement of the pores. The indentation moduli and the hardness are found to decrease nonlinearly with increasing porosity. The bending moduli of the nanohoneycomb structures also decrease nonlinearly as a function of porosity over a large range. It is made clear that the elastic modulus of a homogenous material can be controlled by changing the pore diameter.
Advances in Engineering Software | 2016
Changwoo Lee; Sungnam Lyu; Jae Wan Park; Woonbong Hwang
We performed Lattice Boltzmann simulations of droplet movement of patterned surface.Bond number and interparticle strengths are determined for the simulation.The critical angle which droplet starts to move is affected by Bond number and thickness of the stripes. A stripe-patterned surface with different wettability can be effective for the passive control of droplet movement on a vertical surface. We have performed three-dimensional Lattice Boltzmann (LB) simulations to investigate the effect of the pattern characteristics and liquid properties on the droplet movement. The simulation was initiated by imposing gravity on the droplet formed on the surface. The droplet moves along the direction of the pattern when the angle between the gravity and the pattern is small; however, it starts to overrun the stripes when the angle is greater than a certain value, i.e., critical angle. It is shown that the critical angle decreases as the Bond number increases while it increases as the strength of the adhesion/repulsion force increases. The droplet forms a curved asymmetric boundary on the stripe-patterned surface due to gravity and surface forces. The critical angle is also affected by the thickness of the stripes.
Current Applied Physics | 2013
Handong Cho; Dongseob Kim; Changwoo Lee; Woonbong Hwang
Applied Surface Science | 2014
Changwoo Lee; Handong Cho; Dongseob Kim; Woonbong Hwang
Journal of Power Sources | 2011
Hong-Yue Tang; Anthony D. Santamaria; Jae Wan Park; Changwoo Lee; Woonbong Hwang
The Korean Journal of Gastroenterology | 2002
Sung-Wook Kim; Jeong-Ill Suh; Nam-Il Kim; Goo Lee; Chang-Heon Yang; Changwoo Lee; Ki-Kwon Kim
Archive | 2012
Yonghyun Kim; Si-Yeon An; Changwoo Lee; Jaesung Park; Sangmin Lee; Woonbong Hwang
Archive | 2012
Yonghyun Kim; Siyeon An; Changwoo Lee; Jaesung Park; Sangmin Lee; Woonbong Hwang
Archive | 2012
Woon Bong Hwang; 황운봉; Wan Kyun Chung; 정완균; Jinsung Yoon; 윤진성; Dong Seob Kim; 김동섭; Sangmin Lee; 이상민; Changwoo Lee; 이창우
Archive | 2012
Woon Bong Hwang; 황운봉; Wan Kyun Chung; 정완균; Saejun Park; 박세준; Dong Seob Kim; 김동섭; Sangmin Lee; 이상민; Changwoo Lee; 이창우