• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.407-408
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• 2006

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.616-619
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• 2003

Photochemical and photothermal effects have correlation with each other and depend on laser wavelength. Multi-scanning laser ablation process of polymer with DPSS(Diode Pumped Solid State) 3rd harmonic Nd:YVO$_4$ laser with wavelength of 355nm is applied to fabricate three-dimensional micro shape. The DPSSL photomachining system can rapidly and cheaply fabricate 2D pattern or 3D shape with high efficiency because we only use CAD/CAM software and precision stages instead of complex projection mask. Photomachinability of polymer is highly influenced by laser wavelength and its own chemical structure. So the optical characteristics of polymers for 355nm laser source is investigated by experimentally and theoretically.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1764-1767
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• 2003

It is widely used in composite materials like several mechanical parts. aerospace industries. internal and structural materials of cars, building structures. ship materials and sporting goods. but it is insufficient to apply in field of mechanical processing. Therefore. GFRP which is possible to use in industrial field was examined about cutting force. tool wear condition of cutting, chip shape. surface roughness and inlet or outlet shape of processing parts with changing cutting condition and using HSS drill which is in vertical machining center in this paper.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.573-576
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• 2003

In this paper the following conclusions were obtained after examining and analyzing data through the various experiments by adopting automobile's piston as the experimental materials among the automobile materials which are being commercialized. The various experiments have been carried out with the object of presenting the selection of rational. economic materials and criterion according to the improvement of machining characteristics by grasping the strength and weakness of existing various materials and using the effects of metallic structure variables as well as satisfying the required conditions.

• 대한기계학회논문집
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• 제19권3호
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• pp.680-687
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• 1995

In recent years, grinding techniques for precision machining of brittle materials used in electric, optical and magnetic parts have been improved by using superabrasive wheel and precision grinding machine. The completion of optimum dressing of superabrasive wheel makes possible the effective precision grinding of brittle materials. But the present dressing system cannot have control of optimum dressing of the superabrasive wheel. This study has proposed a new optimum in-process electrolytic dressing system. This system can carry out optimum in-process dressing of superabrasive wheel, and give very effective control according to gap increase.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.414-419
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• 1997

Linear motor feature a direct connection to the machine tool, therefore a direct route for heat transfer. The heat dissipation of linear motor machine is affected by the maximum temperature rise of the primary part, coil and the cooling method. To minimize temperature induced dimension changes and decrements of performance, linear motor machine require effective cooling mechanism. 1'0 evaluate cooling performance of existing linear motor machine, some experiments about temperature profile are performed and evaluated using thermocouple recorder. Due to the lack of information about internal structure. only some finite element modelling is prepared and analyzed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.180-183
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• 1997

The forming process of metal matrix composites by the die casting and squeeze casting process are limited in size and dimension in term of final parts without machining. The thixoforming process for metal matrix composites has numerous advantages compared to die casting, squeeze casting and compocasting. The characteristics of thixoforming process can decrease the liquid segregation because of he improvement in fluidity in a globular microstructure state and utilizes flow without air entrapment. Therefore, in order to obtain the sound parts of metal matrix composites by using thixoforming process which as co-existing solidus-liquidus pahse, it si very important to obtain reheating condition. However, for he thixoforming process, the billet with the desired volume fraction must be heated to obtain a uniform temperature distribution over the entire cross-sectional areas. To obtain the reheating conditions of composites, the particulate reinforced metal matrix composites for thixoforming were fabricated by combined stirring process which is simultaneously performed with electro-magnetic stirring process which is simultaneously performed with electro-magnetic stirring and mechanical stirring process.

• 한국정밀공학회지
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• 제21권10호
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• pp.50-56
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• 2004

Finishing is the final process in molds manufacturing and consumes much process time. Also, it influences on surface quality of molds. But, there are few systematic methods to control the process. In this work, basic experiments were carried out to study the machining characteristics of the finishing tools. From the experiments, critical surface roughness and wear coefficient are suggested to reduce the number of finishing steps and to plan a systematic finishing procedure. Comparison experiments were carried out between the expert's method and the new method, which is based on the results of this research. From the experiments, it is verified that the systematic method takes less time and generates less form error in the machined surface than the worker's method.

• 한국정밀공학회지
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• 제24권2호
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• pp.33-40
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• 2007

In this study, presintered and full sintered low purity alumina ceramics were machined with various tools to clarify the effect of cutting fluid in machinability. The main conclusions obtained were as follows. When the presintered ceramics were wet machined with sintered diamond tool, the tool wear becomes extremely large, and higher cutting speed can be used than in the case of full sintered ceramics. The productivity of wet cutting with the sintered diamond tool is much higher than that of dry cutting. In the case of the CBN and ceramic tools, the tool wear were smaller at wet cutting than at dry cutting, especially exhibiting considerably larger grooved tool wear in wet cutting with ceramic tool.

• International Journal of Precision Engineering and Manufacturing
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• 제9권1호
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• pp.19-24
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• 2008

We propose a new miniature air-bearing stage with a moving-magnet slotless linear motor. This stage was developed to achieve the precise positioning required for submicron-level machining and miniaturization by introducing air bearings and a linear motor sufficient for mesoscale precision machine tools. The linear motor contained two permanent magnets and was designed to generate a preload force for the vertical air bearings and a thrust force for the stage movement. The characteristics of the air bearings, which used porous pads, were analyzed with numerical methods, and a magnetic circuit model was derived for the linear motor to calculate the required preload and thrust forces. A prototype of a single-axis miniature stage with dimensions of $120\;(W)\;{\times}\;120\;(L)\;{\times}\;50\;(H)\;mm$ was designed and fabricated, and its performance was examined, including its vertical stiffness, load capacity, thrust force, and positioning resolution.