• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.211-220
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• 2002

Optical disk drives read information by replacing a laser beam on the disk track. As information has become larger, the more accurate position control of a laser beam is necessary. In this paper, we report the analysis and fabrication of the micro mirror for optical disk drivers. A coupled simulation of gas flow and structural displacement of the micro mirror using the Finite-Element-Method is applied to this. The mirror was fabricated by using MEMS technology. Especially, the process using the lapping and polishing step after the bonding of the mirror and electrode plates was employed for the Process reliability. The mirror size was 2.5mm${\times}$3mm and it needed about 35V for displacement of 3.2 ${\mu}$.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.161-168
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• 2000

In this paper, machining characteristics of glass for HDD media are researched. Nowadays HDD media are used globally as a data storage device. In generally, it is machined by the lapping. But the lapping process time is long and the productivity is low. In this reason, 1 examined the possibility of ELID grinding of glass fur HDD media. If the machining process of HDD media can be changed to ELID grinding, a product cost will be largely saved. The machines used in this experiment were a special rotary type grinder and a normal rotary grinder. The one has an air bearing spindle, the other has not. Experimental results show the possibility of highly efficient grinding and mirror surface can be achieved by the ELID grinding.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.33-33
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• 2004

Traditional bound abrasive grinding leaves the machine marks and subsurface damages ranging from 1 to few tens microns ms in height. These are removed typically by subsequent craftmen-based loose abrasive lapping, polishing and figuring. Using the multi-variable regression technique, we established a new automated grinding process control method for the removal of loose abrasive lapping from the traditional fabrication process. (omitted)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.425-428
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• 1997

Effectiveness of corrective machining algorithm is verified experimentally in this paper by performing corrective lapping work to single side and double sides hydrostatic tables. Lapping is applied as machining method. Machining information is calculated from measured motion errors by applying the algorithm, without information on rail profile. It is possible to acquire 0.13pm of linear motion error, 1.40arcsec of angular motion error in the case of single side table, and 0.07pm of linear motion error, 1.42arcsec of angular motion error in the case of double sides table. The experiment is performed by the unskilled person after he experienced a little of preliminary machining. Experimental results show that corrective machining algorithm is very effective, and anyone can improve the accuracy of hydrostatic table by using the algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.82-85
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• 2003

The sapphire wafers for blue light emitting devices were manufactured by the implementation of the surface machining technology based on micro-tribology. This process has been performed by Micro-lapping process. The sapphire crystalline wafers were characterized by DCXD(Double Crystal X-ray Diffraction). The sample quality of crystalline sapphire wafer at surface has a FWHM(Full Width at Half Maximum) of 250 arcsec. This value at the sapphire wafer surfaces indicated 0.12${\mu}{\textrm}{m}$ sizes. Surfaces of sapphire wafers were mechanically affected by residual stress and surface default. Also Surfaces roughness of sapphire wafers were measured 2.1 by AFM(Atom Force Microscope).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.155-158
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• 2000

Flow defect of a piston-pin for automobile parts is investigated in this study. In cold forging of piston-pin Lapping defect a kind of flow defect appears by the dead metal zone. This appearance evidently happens in products with a thin piercing thickness for the dimension accuracy and the decrease of material loss. The best method that can prevent flow defect is removing dead metal zone. The finite element simulations are applied to analyze the flow defect. This study proposed processes for preventing flow defect by removing dead metal zone. Then the results are compared with the experiments for verification. These FE simulation results are in good agreement with the experimental ones.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.132-137
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• 2001

Application of ceramics, carbide, ferrite has grown considerably due to their mechanical properties such as high degree hardness, chemical stability, super wear resistance. Despite these characters, the use of advanced material has not increased because of poor machinability. The application of metal bonded wheel was proposed. But it is difficult that metal bond wheel can be dressed. Recently, to solve this problem, the technology of in-process electrolytic dressing is developed. This method need wheel for electrolytic dressing, power supply and electrolyte. The aim of this study is development of CIB-D wheel for electrolytic and its evaluation of electrolytic characteristics, and achieve ultra-precision lapping of carbide, optic glass.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.33-33
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• 2004

래핑은 상하정반 사이에 공작물과 공작물을 지지할 수 있는 캐리어를 삽입하여 유성치차운동 방식으로 가공하는 것으로, 오래 전부터 산업전반에 걸쳐 널리 사용되어 왔다. 래핑의 특징은 한번에 많은 수의 공작물을 가공할 수 있어 가공능률이 우수하고, 높은 형상 정밀도를 확보할 수 있을 뿐만 아니라 가공부의 표면 거칠기가 양호하고 가공 변질층이 작다는 이점을 가지고 있다. 특히 박판 형상의 가공물이나 경도에 비해 강도가 취약한 경취성 재질의 가공물을 정밀하고 효과적으로 가공할 수 있기 때문에 최근에는 정밀 기계산업 분야 이외에도 광통신 산업, 반도체 산업, 디스플레이 산업 등에서 그 활용이 점차 증가하고 있는 추세이다.(중략)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.5
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• pp.350-355
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• 2000

The fabrication of sapphire wafer in C plane has been developed by horizontal Bridgeman method and GaN based semiconductor epitaxial growth has been carried out in metal organic chemical vapour deposition. The single crystalline ingot of sapphire has been utilized for 2 inch sapphire wafers and wafer slicing and lapping machines were designed. These several steps of lapping processes provided the mirror-like surface of sapphire wafer. The measurements of the surface flatness and the roughness were carried out by the atomic force microscope. The GaN thin film growth on the developed wafer was confirmed the wafer quality and applicability to blue light emitting devices.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.83-83
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• 2003