• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.10
• /
• pp.1264-1270
• /
• 2004

In this paper research on micro solid propellant thruster is reported. Micro solid propellant thruster has four basic components; micro combustion chamber, micro nozzle, solid propellant and micro igniter. In this research igniter, solid propellant and combustion chamber are focused. Micro igniter was fabricated through typical micromachining and the effect of geometry was evaluated. The characteristic of solid propellant was investigated to observe burning characteristic and to obtain burning velocity. Change of thrust force and the amount of energy loss following scale down at micro combustion chamber were estimated by numerical simulation based on empirical data and through the calculation normalized specific impulses were compared to figure out the efficiency of combustion chamber.

• Transactions of Materials Processing
• /
• v.14 no.5 s.77
• /
• pp.477-481
• /
• 2005

Wafer scale micro mirror array with high surface quality for small form factor (SFF) optical pick-up was fabricated by micro UV-molding. To replicate micro mirror array for SFF optical pick-up, a high- precision mold was fabricated using micro-machining technology. Wafer scale micro mirror array was UV-molded using the mold and then the process was optimized experimentally. The surface flatness and roughness of UV-molded micro mirror array were measured by white light scanning interferomety system and analyzed the transcribing characteristics. Finally, the measured flatness of UV-molded micro mirror away for SFF optical pick-up, which was fabricated in the optimum processing condition, was less than 70nm.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.8
• /
• pp.89-96
• /
• 2004

Micro-tensile testing system, consisting of a micro tensile loading system and micro-ESPI(Electronic Speckle Pattern Interferometry) system, has been developed for measurement of micro-tensile properties of thin micro-materials. Micro-tensile loading system had a load cell with the maximum capacity of 50N and micro actuator with resolution of 4.5nm in stroke. The system was used to apply a tensile load to the micro-sized specimen. During tensile loading, the micro-ESPI system acquired interferornetric speckle patterns in the deformed specimen and measured the in-plane tensile strain. The ESPI system consisted of a CCD-camera with a lens and the window-based program developed for this experiment. Using this system, stress-strain curves for 4 kinds of electrolytic copper foil 18$\square$m thick were obtained. From these curves, tensile properties, including the elastic modulus. yielding strength and tensile strength, were determined and also values of the plastic exponent and coefficient based on Ramberg-Osgood relationship were evaluated.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.623-624
• /
• 2005

Micro injection molding is a branch of micro system technology and has been under development for the mass manufacture of micro parts. Enhanced technological products like micro optical devices are entering the market. This paper presents fundamental research on the injection molding technique in micro fabrication. In order to successful manufacturing of micro plastic parts, it is necessary to research for development of micro-injection machine, machining of micro mold, decision of optimum injection conditions and the research for polymer material. Therefore in this study, in order to machining of micro mold, a mold core with microscopic V-shaped groove was tooled by ultra-precise tooling machine. The transcription experiments with a polymer, PMMA resin on the surface of core with Ni plating were carried out and surface profile of injected parts was measured with AFM.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.4
• /
• pp.97-101
• /
• 2002

Recently, the need for transporting and manipulating minute amount of fluids in microscale channels (so-called micro-fluidics) has been increasing, especially in biotechnology and biochemical processing. This work demonstrates that the so-called mechano-chemical process which consists of mechanical abrasive action combined with chemical process can be used to f뮤ricate micro-fluidic channels more rapidly and cost effectively than other methods. In this work, capillary filling of fluids in micro-channels was investigated by theoretical approaches and experiments. From the experimental results, it is expected that a complex micro-fluidic system can be fabricated using the micro-fabrication technique and microsystem packaging method described in this work.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1902-1906
• /
• 2003

Micro-milling is an efficient method for fabricating micro structures because of its high machining rate compared with other non-conventional micro machining processes. But it is not easy to make a micro milling tool with less than 50 $\mu\textrm{m}$ in diameter by conventional machining. In this study, the characteristics of a micro milling tool fabricated by wire electrical discharge machining (WEDM) were studied. The workpiece is copper and stainless steel. The effects of some machining conditions such as feed rate, depth of cut, and a shape of tool were studied. The tools with D-shape and square shape in cross section were tested for machining micro grooves and 3D structures.

• International Journal of Precision Engineering and Manufacturing
• /
• v.7 no.3
• /
• pp.56-59
• /
• 2006

UV laser micromachining is generally used to create microstructures for micro-products through a sequence of lithography-based photo-patterning steps. However, the micromachining process is not suitable for rapid realization of complex 3D micro-products because it depends on worker experience. In addition, the cost and time required to make many masks are excessive. In this paper, a more effective and rapid micro-manufacturing process, which was developed based on laser micromachining, is proposed for fabricating micro-products directly using UV laser ablation and phase-change filling. The filling process is useful for holding the micro-products during the ablation step. The proposed rapid micro-manufacturing process was demonstrated experimentally by fabricating 3D micro-products from functional UV-sensitive polymers using 3D CAD data.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.1061-1064
• /
• 1997

Micro injection molding technology is very important fiw mass product of micro structures or micro parts. And, it is so difficult that the molding technology of micro pole or thin wall(barrier rib) structures with high aspect ratio. In this stud). \vc intend to research on the basic technology of micro wall structure part:< with high aspect ratio by the inject~on moldins method. The mold for esperimenrs with micro multi-square structures was made by L, I(;A process. One square polc's size is 157 157pm. height 50011111. And the distance of each poles is 5011n1. 7'hus. molding products will be for~nctl like as the net structure with thin wall of about 50pn thickness.(aspect ratio 10) Ihrough the e~lxriment. \be obtained the prociuctr of micro multi-square slructure with bout 37.000 cell per a piece. 'Ihe micro injection molding process technolog for thin wall by multi-square structure mold was analy~cd.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.11 s.176
• /
• pp.196-201
• /
• 2005

UV laser micromachining are generally used to create microstructures for micro product through a sequence of lithography-based photopatterning steps. However, the micromachining process is not suitable for the rapid realization of complex 3D micro product because it depends on worker experiences, excessive cost and time to make many masks. In this paper, the more effective micro rapid manufacturing process, which is developed upon the base of laser micromachining, is proposed to fabricate micro products directly using UV laser ablation and phase change filling. The filling process is useful to hold the micro product during the next ablation step. The proposed micro rapid manufacturing process is also proven experimentally that enables to fabricate the 3D micro products of UV sensitive polymer from 3D CAD data to functional micro parts.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.3
• /
• pp.14-20
• /
• 2002

Recently, miniaturization and mass production are the main trends in manufacturing fields. Therefore, ultraprecision machining and MEMS technology have been taken more 7md more important position in machining of microparts. Micro endmilling is one of the prominent technology that has wide spectrum of application field ranging from duo parts to micro products, such as PDP md IT components, in precision products manufacturing. However, decreasing of burr is significant problem in making smooth and precise parts in micro endmilling. This paper shows removal characteristics of burr generated by micro endmilling process. This results satisfies micro endmilling for micro barrier ribs of heights is $50{\mu}m$, $100{\mu}m$, $200{\mu}m$, $300{\mu}m$, and observation from of burr. Additionally, it is necessary to understand the formation mechanism of burr of micro barrier ribs to iud proper decreasing method.