• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.887-892
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• 2014

In a conventional magnetic abrasive polishing process, the polishing abrasives are mixed with ferrous particles and slight cutting oil to form a cluster of abrasives. However, when a tool rotates at a high revolution speed, most of the polishing abrasives are scattered away from it due to the increase in centrifugal force. This phenomenon directly reduces the polishing efficiency. The use of a highly viscous matter such as silicone gel instead of cutting oil for mixing is one method to solve this problem and increase abrasive adhesion. Another method to avoid high abrasive scattering is the application of wet magnetic abrasive polishing (WMAP). In WMAP, abundant mineral oil is preliminarily applied to the workpiece surface. This study experimentally evaluated the effect of WMAP on abrasive adhesion. The relationship between the amount of working abrasives and polishing conditions was characterized. Despite the lower adhesion ratio of polishing abrasives, the surface roughness was found to be significantly improved as the result of WMAP.

• Restorative Dentistry and Endodontics
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• v.32 no.2
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• pp.138-150
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• 2007

The purpose of this study was to evaluate the difference of surface roughness of composite resin according to composite resin type, polishing methods, and use of resin sealant. Two hundred rectangular specimens, sized $8{\times}3{\times}2mm$, were made of Micro-new (Bisco, Inc., Schaumburg, IL, U.S.A) and Filtek Supreme (3M ESPE Dental Products, St. Paul, MN, U.S.A.), and divided into two groups; Micronew-M group, Filtek Supreme-S group. Specimens for each composite group were subdivided into five groups by finishing and polishing instruments used; M1 & S1(polyester strip), M2 & S2 (Sof-Lex disc), M3 & S3 (Enhance disc and polishing paste), M4 & S4(Astropol) and M5 & S5 (finishing bur), Polished groups were added letter B after the application of resin surface sealant (Biscover), eg, M1B and S1B. After specimens were stored with distilled water for 24hr, average surface roughness (Ra) was taken using a surface roughness tester. Representative specimens of each group were examined by FE-SEM (S-4700: Hitachi High Technologies Co., Tokyo, Japan). The data were analysed using paired t-test, ANOVA and Duncan's tests at the 0.05 probability level. The results of this study were as follows ; 1. The lowest Ra was achieved in all groups using polyester strip and the highest Ra was achieved in M5, S5 and M5B groups using finishing bur. On FE-SEM, M1 and S1 groups provided the smoothest surfaces, M5 and S5 groups were presented the roughest surfaces and voids by debonding of filler on the polished specimens. 2. There was no significant difference in Ra between Micronew and Filtek Supreme before the application of resin sealant, but Micronew was smoother than Filek Supreme after the application of resin sealant. 3. There was significant corelation between Ra of type of composite resin and polishing methods before the application of resin sealant (p=0.000), but no significant interaction between them after the application of resin sealant. On FE-SEM, most of composite resin surfaces were smooth after the application of resin sealant on the polished specimens. 4. Compared with before and after the application of resin sealant in group treated in the same composite and polishing methods, Ra of M4B and M5B was statistically lower than that of M4 and M5, and S5B was lower than that of S5, respectively (p<0.05). In conclusion, surface roughness by polishing instruments was different according to type of composite resin. Overall, polyester strip produced the smoothest surface, but finishing bur produced the roughest surface. Application of resin sealant provided the smooth surfaces in specimens polished with Enhance, Astropol and finishing bur, but not provided them in specimens polished with Sof-Lex disc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.276-281
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• 2014

In this research, we describe a force feedback control for industrial robots has been proposed as a system which is suitable to work utilizing pressure sensitive alternative to human. Conventionally, polished surface of the workpiece are recognized, chamfer ridge, machining processes such as deburring, and it is most difficult to automate because of its complexity, has been largely dependent on the human. To aim to build automatic vacuum system robotic force control was gripping the grinding tool, the present study we examined the adaptability to the polishing process to understand the characteristics of the control system feedback signal obtained from the force sensor mainly. Furthermore, as a field, which holds the key to the commercialization, I went ahead with the application to robotic sweeping machine. As a result, the final sweeping utilizing a robot machine to obtain a very good grinded surface was revealed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.41.4-41
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• 2004

본 발표에서는, 초정밀 연마기의 고성능화와 자동화를 위한 개념설계, 적절한 요소부품의 선택, 그리고 연마공정제어 및 형상오차보정 기술에 대해 설명한다. 초정밀 Polishing 공정이 기존의 개념과는 달리 표면품질의 개선 외에 형상정밀도의 유지 또는 향상 측면에서 기술적 접근이 요구되는 사실에 대해 초점을 맞추었다. 이제 초정밀 연마기는 Nano-meter 수준의 표면 품질과 동시에 형상정밀도 달성의 가능성을 열고 있다.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.50-51
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• 2002

측면 연마된 광섬유 표면 위에 새로운 물질층을 형성시킨 후 광섬유 모드의 소산장(evanescent field) 결합을 유도하여 다양한 능동 및 수동 광섬유로 응용이 가능하다. 광섬유를 연마하기 위하여 쿼츠에 형성된 홈에 광섬유를 에폭시로 고정시키고 쿼츠와 함께 광섬유 클래딩을 연마하는 방법이 잘 알려져 있다. 이러한 방법은 측면 연마된 광섬유를 연마하는데 다소 긴 시간이 필요하다. 본 논문은 광섬의 클래딩을 연마휠로 제거하는 기법을 소개하고 연마된 광섬유의 클래딩 위에 금속이나 유전체층을 결합하여 기능성 광섬유 소자를 제작할 수 있음을 보인다. (중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.1
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• pp.47-49
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• 2003

The cost of material and slicing of silicon wafer occupied more than 30% of solar cell manufacturing cost. The substitution of silicon wafer into STS 304 stainless steel could be the promising solution to decrease the material cost. Moreover the stainless steel solar cell could have the advantage of low weight and durability. However, the highly polished surface is required to meet the characteristic of solar cell. The electropolishing process in phosphoric acid based solution was used to get the surface quality. The obtained result was 28 nm obtained in current density of 2Amfi/$cm^2$ at $80^{\circ}C$. The leveller effect of glycerine, ethylene glycol and propylen glycol was studied. When the 0.4 g/l of ethylene glycol was added to the electrolyte, the surface roughness was best, 15 nm.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.106.1-106.1
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• 2012

EBSD(Electron BackScattered Diffraction)분석은 주사전자현미경에서 관찰되는 비교적 넓은 영역의 결정 방위를 측정하여 집합조직을 해석하는 동시에 결정 방위의 변화를 기준으로 결정립계를 구분 지어 미세조직의 정량 분석도 가능하기 때문에 많은 연구자들이 사용하고 있다. 그러나 EBSD의 Kikuchi 패턴은 시편 표면으로부터 30~50nm 깊이 범위의 표면층으로부터 방출되기 때문에 EBSD 분석 결과는 시편의 표면 처리 상태에 크게 영향을 받아 적절한 시편준비법이 요구된다. 시편 준비 과정 중에 생기는 변형층, 산화층이나 오염층이 10nm 이내로 제어되지 못하면 명확한 패턴을 얻지 못하여 분석이 어려운 경우가 많으므로, 시료의 절단과 연마 과정 중에 변형층을 되도록 적게 만들고 표면의 산화나 오염을 최대한 방지해야 한다. 또한 EBSD 분석 특성상 시편을 70도로 기울이기 때문에 시편의 요철이 심하면 볼록한 영역에 의해 오목한 영역의 패턴이 가려져 결정방위 정보를 얻기 힘들다. 이런 이유로 시편을 최대한 평평하게 하고 요철이 생기지 않게 시편 준비를 하는 것이 관건이다. 금속재료의 EBSD 시편준비법으로는 일반적으로 기계적 연마법과 전해연마법이 주로 쓰인다. 경한 석출물이나 개재물이 연한 기지에 분산되어 있는 시편이나 이종 소재 접합재의 경우는 전해연마법을 사용하면 특정 상(혹은 합금)이 먼저 연마되어 큰 단차가 생기거나 석출물에 의해 요철이 심해져서 정량적인 EBSD 분석이 어렵게 된다. 이 연구에서는 시편 준비가 어렵다고 알려진 다상 금속재료에서의 EBSD 분석 사례를 소개한다. Ti-6Al-4Fe-0.25Si 시효처리합금, 알루미늄 기지 복합재료, 마찰교반용접한 알루미늄-타이타늄합금의 EBSD 시편준비법과 그 분석 결과를 고찰한다.

• Journal of the Korean Vacuum Society
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• v.10 no.3
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• pp.361-367
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• 2001

Recently, Chemical Mechanical Polishing(CMP) has become a leading planarization technique as a method for silicon wafer planarization that can meet the more stringent lithographic requirement of planarity for the future submicron device manufacturing. The SOI(Silicon On Insulator) wafer has received considerable attention as bulk-alternative wafer to improve the performance of semiconductor devices. In this paper, the objective of study is to investigate Material Removal Rate(MRR) and surface micro-roughness effects of slurry and pad in the CMP process. When particle size of slurry is increased, Material Removal rate increase. Surface micro-roughness is greater influenced by pad than by particle size of slurry. As a result of AM measurement, surface micro-roughness was improved from 27 $\AA$ Rms to 0.64 $\AA$Rms.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.42-49
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• 2020

This paper is a basic study to improve durability by imparting hydrophobicity to the surface and sphere of cement-based materials. A cement mortar to which a silane/siloxane-based mixed water repellent was added was prepared, and its initial hydration performance, flow performance, and compressive strength were measured. In addition, after the surface was abraded, the water contact angle and water absorption were measured. The flow of cement mortar to which the water repellent was added was found to decrease up to 1.5% in the addition amount of the water repellent agent, and increased at 3.0% in the addition amount. It was found that the setting time of the cement paste was delayed in both the initial setting and the termination when the water repellent was added. It was found that the compressive strength decreased from 3.0% of the maximum added amount of the water repellent to a maximum of 30%. The contact angle was found to increase when the water repellent was added to the cement mortar, and the contact angle after surface polishing was found to be larger than before surface polishing. The addition of the water repellent showed hydrophobicity not only on the surface but also on the surface and cross section damaged by polishing. The water absorption rate was found to decrease when the water repellent was added to the cement mortar, and the water absorption rate after surface polishing was found to be greater than before surface polishing.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.4
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• pp.195-203
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• 2023

Purpose: This study aimed to evaluate the influence of surface sealants on the surface roughness of composite resins. Materials and Methods: The study used microfilled composite resin (Metafil CX, Sun Medical Co.) and hybrid composite resin (Aelite^TM LS posterior, Bisco). Sixty specimens (8 mm in diameter and 4 mm in height) of each composite resin type were prepared and divided into 3 groups. Each specimen was ground with 600, 1000, and 2000-grit sandpaper. The Surface roughness (Ra) values were measured using a surface roughness tester (SJ-301, Mytutoyo) before and after surface sealant application. Surface sealants, BisCover^TM LV (Bisco), Optiguard^® (Kerr), and Seal-n-Shine^TM (Pulpdent), were applied to the specimens, as instructed and observed by scanning electron microscope (JSM-7500, JEOL) and atomic force microscope (MultiMode IV, Veeco Instruments). Results: Specimens ground with 600-grit sandpaper coated with surface sealants exhibited significantly lower Ra values than the untreated group (P < 0.05). Specimens ground with 1000 and 2000-grit sandpaper showed statistically no difference. There was no significant difference in surface roughness among BisCover^TM LV, Optiguard^®, and Seal-n-Shine^TM. SEM and AFM revealed remarkably decreased microdefects on the surfaces of composite resins after surface sealant application. Conclusion: Surface sealants can influence surface roughness when applied on the rough surface of composite resins but not on highly polished composite resins.