• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.70-73
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• 2002

Using zirconium ceramics makes the ferrule, which is the part of optical communications. The quality of optical communications is directly affected by the concentricity of the optic ferrule. The products of optic ferrule should be meet the following general conditions which are the outer diameter of 2.5mm and the inner diameter of 0.125mm, and high quality conditions which are the concentricity of 0.1~$0.3\mu\textrm{m}$, the form accuracy of $0.2\mu\textrm{m}$, the roundness and the cylindricity of $0.1\mu\textrm{m}$ and the surface roughness of 10nm. Generally, the diamond wheel is used for the high efficiency and precision grinding of the materials. It is good for keeping the shape as it has little wear. Because of the loading phenomena, however, it is difficult to keep the fresh surface of the wheel. In grinding process, grinding fragments resemble fine powders rather than chips. It can easily get attached to the wheel surface and thus cause a loading. The loading takes place, in which the impurities stick to the wheel surface, and the grinding characteristics of wheel is deteriorated. To prevent all of these, a suitable dressing method should be used for the wheel. In this research, the dressing system fur co-axial grinding machine was designed and produced for the machining of ferrule, which is a high performance part. The performance of the developed dressing system was evaluated by measuring the form accuracy of ferrule, which is machined by the dressed wheel in developed dressing system.

• International Journal of Precision Engineering and Manufacturing
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• 제6권1호
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• pp.59-64
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• 2005

This paper describes an investigation about the fluid delivering method that minimizes the generation of hydrodynamic pressure and improves the grinding accuracy. Traditionally, grinding fluid is delivered for the purpose of cooling, chip flushing and lubrication. Hence, a number of conventional investigations are focused on the delivering method to maximize fluid flux into the contact arc between the grinding wheel and the work piece. It is already known that hydrodynamic pressure generates due to this fluid flux, and that it affects the overall grinding resistance and machining accuracy. Especially in the ultra-precision mirror grinding process that requires extremely small amount of cut per pass, its influence on the machining accuracy becomes more significant. Therefore, in this paper, a new delivering method of grinding fluid is proposed with focus on minimizing the hydrodynamic pressure effect. Experimental data indicates that the proposed method is effective not only to minimize the hydrodynamic pressure but also to improve the machining accuracy.

• 한국세라믹학회지
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• 제46권6호
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• pp.545-547
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• 2009

An immiscible Si/Sn (=7/3 by volume) powder mixture was subjected to simple grinding and subsequent leaching process to give Sn nanopowder reinforced or dispersed in Si powder. Crystallite and their agglomerates of Si were ca. 15 nm and 100 nm, respectively. Sn remained at 4.5 vol% in Si powder after aqueous HCl leaching, dispersively occluded in Si matrix as confirmed by ICP analysis and cross sectional TEM observation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.84-87
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• 2001

A demand for the aggregates is increasing in the field of civil and architectural industry and so on. In these industries, the particle size and shape of aggregates are important factors and especially spherical or rounded particles are desired. In Japan, waste glass is used as one of the aggregate materials for the pavement or the construction. In this study based on the frictional action of material on each other, an autogenous grinding of silica glass with a stirred mill were carried out in order to eliminate flakelike or squarish particles and get spherical or rounded ones for aggregate materials. The autogenous grinding experiments were conducted by applying loads to the particle layer of silica glass. The particle shape was evaluated by the shape index, N/T and the degree of circularity, Ψ$_{ci}$ . The unfractured particles (20~13mm) were evaluated by N/T and Ψ$_{ci}$ , and the products (finer than 10${\mu}{\textrm}{m}$) by Ψ$_{ci}$ . As a result, N/T of the unfractured particles decreased with an increase of grinding time. Ψ$_{ci}$ of the unfractured particles and the products increased with an increase of grinding time (; progress of grinding), and became almost constant in the long time grinding. These tendencies were not changed by the applied load on the particle layer, but the limit value of Ψ$_{ci}$ at the products were varied with the applied load.plied load.

• 한국식품영양과학회지
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• 제39권7호
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• pp.1005-1010
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• 2010

본 연구에서는 인삼의 유용성분 강화 및 인삼 전근 활용을 위한 증숙 및 습식분쇄 조건을 조사하였다. 그 결과 무처리(A), $95^{\circ}C$/3 hr(B) 및 $121^{\circ}C$/15 min(C)의 증숙조건에 의해 각각의 당도는 7.7, 10.7 및 $11.2^{\circ}Brix$, 갈색도 0.37, 1.97 및 1.50로 증숙구간에서 당도 및 갈색도가 높게 나타났다. 조사포닌 함량은 7.19(A), 6.99(B) 및 8.83 mg/g(C)으로 C 조건에서 가장 높게 나타났다. 관능검사를 실시한 결과 C 조건에서 쓴맛 감소, 단맛 강도 및 전반적 기호도가 가장 높게 나타나 증숙처리 조건에서 관능적인 특성을 향상시킬 수 있었다. 가수량에 따른 습식분쇄 조건을 조사한 결과 가수량 300%에서 입자가 가장 작게 나타났다. 인삼의 습식분쇄조건은 분쇄 30분 및 3회에서 분쇄효율이 높았으며 평균입자크기는 $67.66\;{\mu}m$로 미세화되었다. 분쇄시간 및 횟수에 따른 유효성분 함량은 큰 차이가 없었다. 이상의 결과 증숙처리($121^{\circ}C$/15 min) 및 습식분쇄는 인삼의 전근 활용 및 유효성분 강화에 효과적인 것으로 확인되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.19-22
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• 2005

As the optical communication industry is developed, the demand of optical communication part is increasing. $ZrO_2$ ceramic ferrule is very important part which can determines the transmission efficiency and information quality to connect the optical fibers. In general $ZrO_2$ ceramic ferrule is manufactured by grinding process because the demands precision is very high. And the co-axle grinding process of $ZrO_2$ ceramic ferrule is to make its concentricity all of uniform before centerless grinding. When co-axle grinding of ferrule supported by two pin, pin chucking alignment accuracy is very important. This paper deals with the analysis of the chucking alignment experiment with parallel error on the micro feeding equipment. Thus, if possible be finding highly good the chucking alignment of two pin.

• Journal of Welding and Joining
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• 제24권2호
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• pp.42-47
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• 2006

While it is known that the weld toe grinding method may give 3.4 times of fatigue strength improvement, this improvement may significantly vary according to weld bead shapes and loading modes. Although tremendous interest have been given in improving fatigue strength improvement for ship structures, quantitative results are yet in need. In this context, a series of fatigue tests is carried out for a type of test specimen that are typically found in ship structures. Weld burr grinding is carried out using a electric grinder in order to remove surface defects and improve the weld bead profile. The test results are compared with the same type of test specimen without applying the fatigue improvement technique in order to obtain a quantitative measure of the fatigue strength improvement. On the other hand, both hot spot stress and structural stress methods are employed to compare the effectiveness of the two methods in evaluating the fatigue strength improvement of welded structures.

• 반도체디스플레이기술학회지
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• 제16권3호
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• pp.47-52
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• 2017

Solar cell industry requires high technologies to stabilize apparatuses for the wafer manufacturing. Vibrations of squaring & grinding machines are one of the most critical factors for causing residual stresses of ingots, which are the main reasons of the breakage in the following processes such as wire sawing, cleaning, and modularity. In this study, the structure of a squaring & grinding machine has been analyzed through experiments and computer simulations to figure out the ways to suppress the vibrations effectively, and further to minimize the breakage of wafers. The result shows that simple design changes of applying a few ribs can improve the stability of the machine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.6-9
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• 2005

In this study, the ultra precision centerless grinder for ferrule grinding was designed. As the good-qualified ferrule is required a precise and fine grinding, grinding machine for ferrule must have a high accuracy and a sufficient stiffness. The centerless grinder is composed of the high damping concrete bed, grinding wheel spindle unit, regulating wheel spindle unit, feeding table and dressing unit. For a newly developed centerless grinder, hydrostatic system with high precision feeding and high stiffness was proposed. The grinding and regulating wheel spindle units were composed of hydrostatic spindle and feeding table was hydrostatic table. The prototype of hydrostatic table was manufactured and tested.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.246-251
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• 2000

In this paper, Wire electric discharge grinding(WEDG) method for manufacturing the micro shaft was introduced and the machining characteristics was investigated. from the experimental results, it was concluded that high surface integrity could be obtained by use of dielectric fluid spraying method and small capacitive condenser.