• International Journal of Korean Welding Society
• /
• v.2 no.2
• /
• pp.19-25
• /
• 2002

In recent years, techniques for micro-assembly with high repeatability under a scanning electron microscope (SEM) are required to construct highly functional micro-devices. Adhesion phenomenon is more significant for smaller objects, because adhesional force is proportional to size of the objects while gravitational force is proportional to the third power of it. It is also known that adhesional force between micro-objects exposed to Electron Beam irradiation of SEM increases with the elapsed time. Therefore, mechanical manipulation techniques using a needle-shaped tool by adhesional force are often adopted in basic researches where micro-objects are studied. These techniques, however, have not yet achieved the desired repeatability because many of these could not have been supported theoretically. Some techniques even need the process of trial-and-error. Thus, in this paper, mechanical and adhesional micro-manipulation are analyzed theoretically by introducing new physical factors, such as adhesional force and rolling-resistance, into the kinematic system consisting of a sphere, a needle-shaped tool, and a substrate. Through this analysis, they are revealed that how the micro-sphere behavior depends on the given conditions, and that it is possible to cause the fracture of the desired contact Interfaces selectively by controlling the force direction in which the tool-tip loads to the sphere. Based on the acquired knowledge, a mode diagram, which indicates the micro-sphere behavior for the given conditions, is designed. By referring to this mode diagram, the practical technique of the pick and place manipulation of a micro-sphere under an SEM by the selective interface fracture is proposed.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1998.02a
• /
• pp.18-18
• /
• 1998

F First I will introduce our works how to improve the crystal growth t technique for Rare earth pnictides and chalcogenides. All these substances h have hi양1 vapor pressure and high melting print up to 3$\alpha$)()C. 까len we employ m the tungsten or molybden crucibles and enclose the sample by 빼e welding of m the lid with high current electron beam. We cannot elevate the temperature up t to 3$\alpha$)()C without suitable radiation shield because rate of radiation loss r rapidly increase in such a high temperature regions. There were no good r radiation shield but we discovered that the p-BN could work as an excellent r radiation shield after checking of the many substances. S Secondly I will show several interesting and unusual 뻐ysical properties of obtained crystals under high magnetic field, hi양1 pressure and also i including angle resolve photoemission spectroscopy. I will stress the p properties of the low carrier concentration with strong correlation on C댐, U USb and Yb4As3

• Transactions of Materials Processing
• /
• v.12 no.5
• /
• pp.487-492
• /
• 2003

Tension variations with heat treatment in shadow mask for flat braun tubes are investigated in this study. In CRT, landing shift of the electron beam due to thermal deformation of the tension mask made the color purity of screen worse. In order to get the final results of thermal deformation, the tensile force within the mask and the welding processes between the rail and the extended mask have to be analysed sequentially. In this study, the effect of heat treatment is studied in terms of tension variations of shadow mask during its manufacturing process.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.11a
• /
• pp.114-118
• /
• 2007

Design and fabrication of a 30-tonf-class full-scale regenerative cooling combustion chamber of a liquid rocket engine for a ground hot firing test are described. It has chamber pressure of 60 bar and nozzle expansion ration of 12 and manufactured to have a single welded structure of· the mixing head and the chamber. The material of the mixing head is STS316L which has excellent mechanical property in cryogenic condition. The chamber comprise of the cylinder, nozzle throat, and 1st/2nd nozzle parts. The material of the inner jacket is copper alloy/STS329J1/STS316L and that of the outer jacket is STS329J1. The components of· the combustor were manufactured by mechanical processing including lathing, milling, MCT, rolling and pressing. The machined components were integrated to a single body by means of general welding, electron beam welding(EBW), and brazing.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.720-725
• /
• 2002

In recent years, techniques for micro-assembly with high repeatability under a scanning electron microscope (SEM) are required to construct highly functional micro-devices. Adhesion phenomenon is more significant for smaller objects, becanse adhesional force is proportional to size of the objects while gravitational force is proportional to the third power of it. It is also known that adhesional force between micro-objects exposed to Electron Beam irradiation of SEM increases with the elapsed time. Therefore, mechanical manipulation techniques using a needle-shaped tool by adhesional force are often adopted in basic researches where micro-objects are studied. These techniques, however, have not yet achieved the desired repeatability because many of these could not have been supported theoretically. Some techniques even need the process of trial-and-error. Thus, in this paper, mechanical and adhesional micro-manipulation are analyzed theoretically by introducing new physical factors, such as adhesional force and rolling-resistance, into the kinematic system consisting of a sphere, a needle-shaped tool, and a substrate. Through this analysis, they are revealed that how the micro-sphere behavior depends on the given conditions, and that it is possible to cause the fracture of the desired contact interfaces selectively by controlling the force direction in which the tool-tip loads to the sphere. Based on the acquired knowledge, a mode diagram, which indicates the micro-sphere behavior for the given conditions, is designed. By refening to this mode diagram, the practical technique of the pick and place manipulation of a micro-sphere under an SEM by the selective interface fracture is proposed.