• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.45-48
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• 2001

SL(Stereolithogrphy) part is made by piling up thin layers which causes the stair stepping effect at the surface of SL parts. This effect causes excessive surface roughness and requires additional postprocess finishing such as abrasive basting which is detrimental to part geometry and time consuming. Hence paraffin coating and grinding postprocess is proposed to raise the surface quality of SL part. The paraffin which has suitable properties for the proposed postprocess is coated all over the part surface. By grinding the thin layer of coated on the SL part only, the surface roughness can be improved without any damage on the part. From the experimental result, It is verified as very practical for die casting with silicon rubber mold.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.8-13
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• 1996

A relatively new non-traditional finishing process called Abrasive Flow Machining(AFM) is being used to deburr, polish and radius workpiece or produce compressive residual stresses by flowing an abrasive-laden viscoelastic compound across the surface to be machined. This paper presents the effects of AFM on surfaces of tool steel produced by EDM and W-EDM. Using AFM, white layer produced by EDM is erased almost equally and the amount of metal removal is significantly affected the initally machined surface condition of workpiece. The dimension of workiece is enlarged and its surface roughness is improved as AFM time is increased. The optimal AFM time can be established from the experimental results. It is considered that the grinding method lide AFM is useful to grind complex or slim geometry of workpiece even. Scanning Electron Microscopy(SEM) was used to study the surface characteristics of the workpiece before and after AFM.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.943-946
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• 1997

Electropolishing is the controlled electrochemical removal of surface metal, resultmg in a brilliant appearance andimproved properties. Sometimes described as "reverse plating," the process has a leveling effect, which produces smoothnessand increased reflectivity. Unlike conventional mechanical finishing systems, the electropolishing does not smear, bend,stress or fracture the crystalline metal surface to achieve smoothness. Instead, electropolishing removes metal from thesurface producing a unidirectional pattern that is stress-free, microscopically smooth and often highly reflective. In addition,improved corrosion resistance and passivity are achieved on many ferrous and some non-ferrous alloys. Pure aluminium doesnot electropolish well, if at all, but most other alloys of aluminum electropolish excellently.Therefore, the aim of this study is to determine the characteristics of electropolishing aluminium alloy in term of currentdensity, machining time, temperature, electrode gap and workpiece surface measurementkpiece surface measurement

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.565-568
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• 2003

In this paper we deal with behavior of the magnetic abrasive using Ba-Ferrite on polishing characteristics in a new internal finishing of STS304 pipe applying magnetic abrasive polishing. The magnetic abrasive using Ba-Ferrite grain WA was used to resin bond fabricated at low temperature. And Ba-Ferrite of magnetic abrasive powder was crused into 200 mesh. The previous research made an experiment in the static and the dynamic state on the movement of magnetic abrasive grain. In this paper. We investigated into the changes of the movement of magnetic abrasive grain. In reference to this result. we have made the experiment which is set under the condition of the magnetic flux density. polishing velocity according to the form of magnetic brush.

• International Journal of Precision Engineering and Manufacturing
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• 제2권4호
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• pp.47-53
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• 2001

This study is to investigate the problem of the SPM(Skin Pass Mil7) system which is a finishing treatment of steel sheet. and to develop a PID control scheme to minimize process instability. An electrohydraulic servo system with conventional proportional controller used to regulate the force on the strip works inadequately to yield very undesirable transient responses at the moments welding parts of the strip conte into and pass through the rolls. Both linearized and nonlinear models of a typical SPM system ware simulated first by using Simulink. Then Ziegler-Nichols ultimate cycling method was used for an initial reference guide to tune PID gains, and further fine tuning was performed to get desirable response. The test result in the plant show that proposed PID control scheme successfully improves the process instability in a SPM system.

• 한국정밀공학회지
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• 제12권12호
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• pp.5-18
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• 1995

연삭 가공은 인류가 생존을 위한 도구를 만들 때 사용한 2,000년 이상의 가장 긴 역사를 가지는 가공법이며 다른 기계에서 가공된 것을 마지막으로 마무리(Finishing)작업을 하는 가공이다. 연삭 공작기계 발달은 숫돌(Grinding wheel) 기술 발달과 연삭가공 기술 발달과 더불어 진행되어 왔다. 기록에 의하면 1846년 미국에서 선반에 숫돌을 붙인 장치가 등장했으며 이것이 세계 최초의 연삭반이라고 볼 수 있다. 미국 Brown & Sharp사는 1876년 만능 연삭기를 제작했고 미국 Norton사가 평면 연삭기(Surface Grinding Machine)를 제작하였다. 숫돌(Grinding wheel)의 원료인 Carborundum의 제조 방법을 1891년에 Norton사에서 발명하였으며 원통 연삭반은 그 회사가 1901년에 제작하였다. 1924년 Swiss에서 Lead screw 연삭기를 제작하였으며 1930년에 독일 Berlin 대학의 Schesinger 교수가 연삭이론의 기초가 되는 연삭력에 대한 이론을 발표하였다.

• International Journal of Precision Engineering and Manufacturing
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• 제3권1호
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• pp.5-12
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• 2002

The grinding process has been mainly used fur finishing metal products as final machining stage. But chatter vibration and bum of a workpiece have a bad effect on the machined surface and should be detected in modern grinding process. This paper deals with a fault detection of the cylindrical plunge grinding process by power parameters. During the grinding process the power signals of an induced motor were sampled and used to determine the relationship between fault and change of power parameters. A neural network was used far detecting the grinding fault and an influence of power parameters to the grinding fault was analyzed.

• 한국정밀공학회지
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• 제18권10호
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• pp.178-183
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• 2001

Abrasive jet machining(AJM) process is similar to the sand blasting and effectively removes hard and brittle materials. AJM has applied to rough working such as debarring and rough finishing. As the need for machining of ceramics, semiconductor, electronic devices and LCD are increasing, micro AJM is developed, and has become the inevitable technique to micromachining. This paper describes the performance of the micro AJM in micro grooving of glass. Diameter of hole and width of line in grooving is 80${\mu}{\textrm}{m}$. Experimental results showed good performance in micro grooving of glass, but the size of machined groove increased about 2~4${\mu}{\textrm}{m}$. With the fine tuning of masking process and compensation of film wear. this micro AJM could be effectively applied to the micro machining of semiconductor, electronic devices and LCD.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.98-102
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• 1994

There are many difficulties in automatic polishing for die & mold surfaces. Even though the process has been studied in the past 15 years, it has not been achieved yet, but by the process of actual hand work of well-skilled workers. A new magentic assisted polishing process, which is one of the potential method for automation of surface finishing has been studied in the past 10 years by colleagues. The process has many merits, but on the other hand also has demerits, one being low efficiency of gridability by comparision with grinding wheel polish. Therefore, some attempts were tried to improve the grindability by adopting electropolishing, ultra-high speed milling, 5-axis controlled machine etc... most recently by collegues. This study also aims to improve the efficiency of polishing by introducing the easily-polished shape surface milling method equalizing the tool feed per tooth to the pick feed. This milling method was experimentally confirmed to have sufficient grindability to polish milled surface (with 10 .mu. mRmax surface roughness) into mirror surface (with 0.4 .mu. mRmax surface roughness).

• International Journal of Precision Engineering and Manufacturing
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• 제8권3호
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• pp.24-44
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• 2007

Cylindrical grinding is one of the important metal cutting processes used extensively in the finishing operation of discrete components. The inherent high cutting temperature in grinding if not controlled may lead to rapid tool wear, which in turn will lead to dimensional inaccuracy. The very nature of the grinding mechanism in material removal impairs the grounded surfaces by inducing residual stress, micro cracks and other thermal damages at the machined surface. This paper is an attempt to review some of the surface integrity issues in cylindrical grinding taken up and reported by number of researchers over the years. This review may have been planned to be useful to the researchers and other professionals interested to work on grinding.