• Structural Engineering and Mechanics
• /
• v.29 no.1
• /
• pp.113-116
• /
• 2008

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.441-442
• /
• 2002

Chemical mechanical polishing (CMP) is a manufacturing process that uses controlled wear to planarize dielectric and metallic layers on silicon wafers. CMP experiments revealed that a sub-ambient film pressure developed at the wafer/pad interface. Additionally, dishing occurs in CMP processes when the copper-in-trench lines are removed at a rate higher than the barrier layer. In order to study dishing across a stationary wafer during polishing, dishing maps were created. Since dishing is a function of the total contact pressure resulting from the applied load and the fluid pressure, the hydrodynamic pressure model was refined and used in an existing model to study copper dishing. Density maps, highlighting varying levels of dishing across the wafer face at different radial positions, were developed. This work will present the results.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.435-437
• /
• 2002

Polishing of copper, a process called copper chemical mechanical polishing, is a critical, intermediate step in the planarization of silicon wafers. During polishing, the electrodeposited copper films are removed by slurries: and the differential polishing rates between copper and the surrounding silicon dioxide leads to a greater removal of the copper. The differential polishing develops dimples and furrows; and the process is called dishing and erosion. In this work, we present the results of experiments on dishing and erosion of copper-CMP, using patterned silicon wafers. Results are analyzed for the pattern factors and properties of the copper layers. Three types of pads - plain, perforated, and grooved - were used for polishing. The effect of slurry chemistries and pad soaking is also reported.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.651-652
• /
• 2005

Chemical mechanical polishing (CMP) has emerged as the planarization technique of choice in integrated circuit manufacturing. Especially, polishing pad is considered as one of the most important consumables because of its properties. Generally, conventional polishing pad has irregular pores and asperities. If conditioning process is except from whole polishing process, smoothing of asperities and pore glazing occur on the surface of the pad, so repeatability of polishing performances cannot be expected. In this paper, CMP pad with microstructure was made using micro-molding technology and repeatability of ILD(interlayer dielectric) CMP performances and was evaluated.

• International Journal of Vascular Biomedical Engineering
• /
• v.2 no.1
• /
• pp.1-10
• /
• 2004

Circulatory disease is the number two cause of death next to cancer in Korea, while the cardiovascular disease alone is the number one cause of death in the US. In the present article, some background, current status and future prospects of biomedical engineering esearch on circulatory disorders are discussed in terms of the origin of atherosclerosis, computational fluid dynamics and medical imaging techniques, clinical treatments and fluid dynamics, advances in stents, hemodynamic analysis of artificial heart, and artificial blood. In particular, the importance of close collaboration of medicine and fluids engineering is emphasized.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2007.05a
• /
• pp.255.2-255.2
• /
• 2007

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.3
• /
• pp.356-363
• /
• 2014

This paper covers improvement of the humanoid robot platform HUBO2, known as the HUBO2+. As a necessity of the growth of the humanoid platform, a robust, reliable and user friendly platform is needed. From this standpoint, HUBO2+ is the most improved humanoid robot platform in the HUBO series. The mechanical design has been changed to increase the movable range and to stop joint compulsion. Additionally, all of the electrical parts are re-designed to be un-breakable in an unexpected situation. A smart power controller with robot status check panel is attached on the back. Additionally, a diagnosis tool, the HUBO-i, has been developed. Moreover, each joint motor controller of HUBO2+ has a Protection Function and a PODO system is provided for handling the robot easily.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.12
• /
• pp.1155-1159
• /
• 2014

Thermal barrier coating (TBC) which is used to protect the substrate of gas turbine is exposed to high temperature environment. Because of high temperature environment, thermally grown oxide (TGO) is grown at the interface of thermal barrier coating in operation of gas turbine. The growth of TGO critically affects to durability of TBC, so the evaluation about durability of TBC with TGOs of various thickness is needed. In this research, TGO was inserted by aging of TBC specimen to evaluate the effect of the TGO growth. Then thickness of TGO was defined by microstructure analysis, and thermal fatigue test was performed with these aging specimens. Finally, the relation between thermal fatigue life and the TGO growth according to aging time was obtained.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.25 no.4
• /
• pp.364-371
• /
• 2022

Surface state change of ammunition generated during the storage period increases the surface roughness and this affects the flight of ammunition, but there are no research results quantitatively indicating this. In this study, the drag force for each Mach number of howitzer shells was calculated through CFD to which the surface data of the howitzer shell was applied, and analysis of trajectory was performed using drag force values as an input of the 4th Runge-Kutta method, and the degree of decrease of the maximum range caused by the surface roughness of the howitzer shell was estimated. As a result, it was confirmed that the maximum range of howitzer shell with high surface roughness was 1.12 % shorter than that of howitzer shell without roughness. It was confirmed that the effect of surface roughness on the trajectory is not negligible.

• The Journal of Korea Robotics Society
• /
• v.17 no.2
• /
• pp.198-208
• /
• 2022

In this paper, an autonomous driving system is implemented for the Segye AI Robot Race Competition that multiple vehicles drive simultaneously. By utilizing the ERP42-racing platform, RTK-GPS, and LiDAR sensors provided in the competition, we propose an autonomous driving system that can drive safely and quickly in a road environment with multiple vehicles. This system consists of a recognition, judgement, and control parts. In the recognition stage, vehicle localization and obstacle detection through waypoint-based LiDAR ROI were performed. In the judgement stage, target velocity setting and obstacle avoidance judgement are determined in consideration of the straight/curved section and the distance between the vehicle and the neighboring vehicle. In the control stage, adaptive cruise longitudinal velocity control based on safe distance and lateral velocity control based on pure-pursuit are performed. To overcome the limited experimental environment, simulation and partial actual experiments were conducted together to develop and verify the proposed algorithms. After that, we participated in the Segye AI Robot Race Competition and performed autonomous driving racing with verified algorithms.