• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.59-66
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• 2003

This study suggests the new ultraprecision finishing techniques for micro die and mold parts using magnetic field-assisted polishing. Conventional magnetic abrasives have several disadvantages, which are missing of abrasive particle and inequal mixture between magnetic particle and abrasive particle. Therefore, bonded magnetic abrasive particles are fabricated by several method. For example, plasma melting and direct bonding. Carbonyl iron powder is used as magnetic particle there silicon carbide and alumina are abrasive particles. Developed magnetic abrasives are analyzed using SEM. Feasibility of magnetic abrasive and polishing performance of this magnetic abrasive particles also have been investigated. After polishing, surface roughness of workpiece is reduced from 85.4 ㎚ Ra to 9 ㎚ RA.

• Textile Coloration and Finishing
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• v.12 no.5
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• pp.273-279
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• 2000

Interlace textured yarn was developed in order to increase weaving process efficiency. Today, interlace texturing is very useful method of manufacturing the high added value compound yarns for new synthetic fabrics. In this research, new silky type high added value compound yarns were. manufactured by interlace texturing technology and tested their properties. The object of this research is to investigate the relationship between interlace textured yarn properties and processing parameters that is air pressure, yarn tension and take-up speed. The original filament yarns used were TTD(Thick & Thin Semi-Dull) 110d/72f and SCD(Semi-Dull Cation Dyeable) 75d/36f. 27 specimens were manufactured and tested for their physical properties-nip density, tensile properties, multi-step shrinkage test and surface structure by SEM. The air pressure was main process condition to change properties of interlace textured yarns. And interlace textured process had influence on weaving preparation process, weaving, knitting and so on. It has some influence on shrinkage properties of dyeing and finishing processes.

• The Journal of Advanced Prosthodontics
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• v.16 no.1
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• pp.25-37
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• 2024

PURPOSE. To investigate the effect of sintering programs and surface treatments on surface properties, phase transformation and flexural strength of monolithic zirconia. MATERIALS AND METHODS. Zirconia specimens were sintered using three distinct sintering programs [classic (C), speed (S), and superspeed (SS)] (n = 56, each). One sample from each group underwent scanning electron microscopy (SEM) and grain size analysis following sintering. Remaining samples were divided into five subgroups (n = 11) based on the surface treatments: control (CL), polish (P), glaze (G), grind + polish (GP), and grind + glaze (GG). One sample from each subgroup underwent SEM analysis. Remaining samples were thermally aged. Monoclinic phase volume, surface roughness, and three-point flexural strength were measured. Monoclinic phase volume and surface roughness were analyzed by Kruskal-Wallis and Dunn tests. Flexural strength was analyzed by two-way ANOVA and Weibull analysis. The relationships among the groups were analyzed using Spearman's correlation analysis. RESULTS. Sintering program, surface treatment, and sintering × surface treatment (P ≤ .010) affected the monoclinic phase volume, whereas the type of surface treatment and sintering × surface treatment affected the surface roughness (P < .001). Type of sintering program or surface treatment did not affect the flexural strength. Weibull analysis revealed no significant differences between the m and σ_o values. Monoclinic phase volume was positively correlated with surface roughness in the SGG and SSP groups. CONCLUSION. After sintering monolithic zirconia in each of the three sintering programs, each of the surface treatments can be used. However, for surface quality and aging resistance, G or GG can be recommended as a surface finishing method.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.12
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• pp.1749-1755
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• 2002

본연구의 목적은DP가공에 의한 가교화를 통해 텐셀의 피브릴화를 조절할 때 DP가공 방법 및 NaOH전처리 효과를 물성, 표면형태, 역학적 성질 및 태의 변화의 관점에서 고찰하는데 있다. SEM 분석결과DP가공에 의해 피브릴 발생 정도는 감소하였다. DP가공 방법에 있어 서 WF법과 PDC법에 따른 물성의 차이는 나타나지 않았다. 역학적특성의 경우 DP가공은 DP가공 방법에 상관없이 효소처리한 직물의 인장선형성에는 큰 영 향을 주지 않았으나 인장에 너지, 굽힘 강성, 압축선형성, 압축 레질리언스, 기하학적 거칠기는 감소시켰고 인장 레질리언스, 굽힘이력, 압축에너지는 증가시켰다. 전단특성은 WF법에서는 증가한 반면, PDC법에서는 감소하여 DP가공 방법에 따른 차이를 나타내었다. WF법이 PDC법보다 더 높은 Koshi, Numeri, Fukurami 값을 보였으며, 종합태 값은 비슷하게 나타났다. NaOH 전처 리에 의해 수지부착량은 감소하였으나 감량률은 증가하였으며, DP성/물성은 더 낮게 나타났다. NaOH 전처리에 의해 인장선형성, 인장에너지, 압축 레질리언스, 전단 및 굽힘특성은 증가하였으나 인장레질리언스와 압축선형성, 압축에너지, 표면특성은 감소하였다. NaOH 전처리한 경우 Koshi는 증가하였고, Numrei와 Fukuramil는 감소하였으며, 종합태 값은 가장 낮았다. 처리한 시료들은 각각 다른 감성과 촉감을 나타냈다.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.59-65
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• 1996

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 methods 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 grindability by comparision with 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 colleagues. This paper also aims to improve the efficiency of polishing by introducing the easily-polished shape surface cutting method equalizing the tool feed per revolution to the pick feed. This cutting method was experimentally confirmed to have sufficient grindability to polish milled surface (with $10{{\mu}m}$Rmax surface roughness) into mirror surface (with $0.4{{\mu}m}$Rmax surface roughness).

• Design & Manufacturing
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• v.13 no.1
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• pp.13-18
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• 2019

The size and prospects of the domestic semiconductor equipment market are increasing every year. In the case of various parts used inside semiconductor equipments, high durability such as high strength and abrasion resistance is demanded. Particularly, the gases used in semiconductor production processes are toxic. In order to prevent such toxic gas leakage, a precision processing technique and a surface treatment technique for preventing corrosion are required. Electro-polishing is an electro-chemical method of polishing a metal surface to make it smooth and polished. Electro-polishing is mainly used in the finishing process of metal surface. Unlike mechanical polishing, electro-polishing is used in many fields, such as fine chemical etching equipment, since no damaged layer or burr, fine polishing groove and particles are generated. However, in order to withstand the gas used in the semiconductor equipment, the parts must have high corrosion resistance. However, the surface hardness generally become lowered through electro-polishing. Therefore, in this study, surface hardness were experimentally observed before and after electro-polishing. Then, a method of improving hardness by preparing a nitrided layer by plasma ion nitriding treatment.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.293-305
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• 2005

Statement of problems. Conventional feldspathic porcelain is used extensively as a restorative material and it is subjected to grinding and polishing during fabrication and delivery procedures. There is still considerable controversy concerning the best methods to achieve the strongest porcelain restorations after such adjustments. Purpose. The objective of this study was to investigate the effects of (1) overglazing, (2) selfglazing, and (3) fine polishing on the flexural strength and fracture toughness of feldspathic dental porcelain. Material and method. Ninety porcelain disks were prepared for flexural strength test and sixty porcelain disks were fabricated for fracture toughness test. Specimens were divided into three groups for each test as follows: 1) overglazed 2) self-glazed 3) polished. The flexural strength of feldspathic porcelains was determined by ring-on-ring biaxial flexural strength test. The fracture toughness values of three experimental groups were obtained by indentation fracture toughness test. Results. The flexural strength of overglazed group was significantly higher than that of selfglazed and polished group (P<0.05), while the difference between self-glazed and polished group was not significant (P>0.05). The fracture toughness values of overglazed and polished group were significantly higher than that of self-glazed group (P<0.05), while the difference between overglazed and polished group was not significant (P>0.05). Conclusions. This results supported the use of polishing as an alternative to glazing metal ceramic restorations, as it was not detrimental in flexural strength and fracture toughness. But, under the conditions of this study, overglazing was the ideal surface finishing method of feldspathic dental porcelain.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.89-96
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• 2006

In this study, fabrication of the large area silicon mirror is accomplished by anisotropic wet etching using micromachining technology for implementation of integrated slim optical pickup and the process condition is also established for improving the mirror surface roughness. Until now, few results have been reported about the production of highly stepped $9.74^{\circ}$ off-axis-cut silicon wafers using wet etching. In addition rough surface of the mirror is achieved in case of tong etching time. Hence a novel method called magnetorheolocal finishing is applied to enhance the surface quality of the mirror plane. Finally, areal peak to valley surface roughness of mirror plane is reduced about 100nm in large area of $mm^2$ and it is applicable to optical pickup using infrared wavelength.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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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.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.488-502
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• 2020

In this study, the moisture absorption and desorption properties presented by the Health-Friendly Housing Construction Standards of South Korea were compared using the wood of three tree species (Douglas-fir, Hinoki, Larch) and two types of wood-based materials(Plywood, WML Board^Ⓡ). The national standards for functional building materials present that the amounts of moisture absorption and desorption should be at least 65g/㎡ on average, respectively according to the test method under KS F 2611:2009. Therefore, in this study, the moisture absorption/desorption properties of materials with no treatment (Control), with punching, and with surface stain finishing and the moisture absorption/desorption property improvement effects of the treatments were compared and analyzed. According to the results of this study, it was evaluated that all five types of wood and wood-based materials tested did not satisfy the amount of moisture absorption/desorption of at least 65g/㎡, which is the performance standard for moisture absorption/desorption functional building materials, indicating that untreated wood and wood-based materials cannot be applied as functional finishing materials according to the Health-Friendly Housing Construction Standards. The surface stain finishing greatly reduced the moisture absorption and desorption rates of the materials, and the amounts of moisture absorbed and desorbed were also shown to decrease by at least two times on average. When the surfaces of the materials were punched with Ø4mm holes at intervals of 20 mm, the moisture absorption/desorption areas increased from 18% to 51%, and this increase was shown to be capable of increasing the amounts of moisture absorbed/desorbed by 29% on average at the minimum, and 81% on average at the maximum. The effects of punching were shown to be identical even in cases where the materials were stain finished. For the application of wood or wood-based materials as eco-friendly, health-friendly, and moisture absorption/desorption functional building materials hereafter, it is judged that new physical and chemical improvement studies should be conducted, and treatment methods should be developed.