• 한국전기전자재료학회논문지
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• 제20권3호
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• pp.234-239
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• 2007

This paper describes the TiW ohmic contact characteristics under the surface treatment of the polycrystalline 3C-SiC thin film grown on $SiO_2/Si(100)$ wafers by APCVD. The poly 3C-SiC surface was polished by using CMP(chemical mechanical polishing) process and then oxidized by wet-oxidation process, and finally removed SiC oxide layers. A TiW thin film as a metalization process was deposited on the surface treated poly 3C-SiC layer and was annealed through a RTA(rapid thermal annealing) process. TiW/poly 3C-SiC was investigated to get mechanical, physical, and electrical characteristics using SEM, XRD, XPS, AFM, optical microscope, I-V characteristic, and four-point probe, respectively. Contact resistivity of the surface treated 3C-SiC was measured as the lowest $1.2{\times}10^{-5}{\Omega}cm^2$ at $900^{\circ}C$ for 45 sec. Therefore, the surface treatments of poly 3C-SiC are necessary to get better contact resistance for extreme environment MEMS applications.

• Journal of Welding and Joining
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• 제35권3호
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• pp.28-34
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• 2017

The authors derived the criteria on the process parameters of laser depositions with metal powers(SUS316L & IN718) by evaluating the surface and cross-section properties of the deposition layers. The surface characteristics of the deposition layer are investigated through optical microscopy by controlling the process parameters of laser output, powder feeding rate and gas feeding rate. The cross-section characteristics were also analyzed after polishing and chemical etching process. As the gas feeding rate increased, the amount of powder loss increased and the difference in the dilution ratio and heat affected zone depending on laser outputs was observed. In addition, the powder feeding rate used in the experiment did not interfere with the energy absorption of the base material.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.162-165
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• 2003

The corrosion characteristics of diffusion barrier in Copper CMP has been investigated. Key experimental variables that has been investigated are the corrosion rate by different agents containing slurry of Cu CMP. Whenever Cu and Ta films were corroded adding each oxidizer, the corrosion rate of Ta was much lower than that of Cu. That is, the difference in the corrosion rates of Ta by oxidizer was not larger as compared with Cu. As corroded by complexing agents, the corrosion rate of Ta was close to O. The corrosion rate of Ta increased as added $HNO_3$ and $CH_3COOH$ compared with the reference slurry; on the other hand, it decreased with addition of HF. In addition, resulting corrosion rate went up with lower pH of agent. The corrosion rates by agents were however significant small; hence, it doesn't affect on the removal rate of Cu CMP practically. Consequently, this can be explained by assuming that the mechanical effect dominates than the chemical effect on the polishing rate of Ta(TaN).

• Journal of Welding and Joining
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• 제19권1호
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• pp.33-39
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• 2001

The welding quality by Gas Tungsten Arc Welding shows very high level, but the welding speed is lower than that of gas metal arc welding. Also, the welding quality by automatic GTAW is variable as the arc characteristics is changed by the consumption of electrode tip. The purpose of this study is to investigate the relation between the properties of tungsten electrode tip and the various arc characteristics at high current region. In this study, the high welding current 200A was applied to the repeated arc start test and long term arcing test using the $\phi$3.2 tungsten electrodes with cone angle 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$sharp tip, and 60$^{\circ}$surface polished (S.P.) sharp tip. It was confirmed that the maximum arc pressure by the initial electrode condition was highest in 45$^{\circ}$sharp tip, and the next in 60$^{\circ}$sharp tip, the last was in 30$^{\circ}$sharp tip and 60$^{\circ}$S.P.. But, the maximum arc pressure after the repeated arc start test and long term arcing test was decreased considerably. But, the maximum arc pressure was highest also in 45$^{\circ}$ sharp tip after the tests, the next was in 30$^{\circ}$sharp tip, and the last was in 60$^{\circ}$sharp tip and 60$^{\circ}$S.P.. The arc start characteristics was the most excellent in 60$^{\circ}$S.P., By long term arcing test, the lanthania included in tungsten electrode was extinguished at tip surface preferentially, therefore the arc characteristics of electrode tip got worse.

• Restorative Dentistry and Endodontics
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• 제24권2호
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• pp.299-309
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• 1999

The composite resin, due to its esthetic qualities, is considered the material of choice for restoration of anterior teeth. With respect to shade control, the direct-placement resin composites offer some distinct advantages over indirect restorative procedures. Visible-light-cured (VLC) composites allow dentists to match existing tooth shades or to create new shades and to evaluate them immediately at the time of restoration placement. Optimal intraoral color control can be achieved if optical changes occurring during application are minimized. An ideal VLC composite, then, would be one which is optically stable throughout the polymerization process. The shade guides of the resin composites are generally made of plastic, rather than the actual composite material, and do not accurately depict the true shade, translucency, or opacity of the resin composite after polymerization. So the numerous problems associated with these shade guides lead to varied and sometimes unpredictable results. The aim of this study was to assess the color changes of current resin composite restorative materials which occur as a result of the polymerization process and to compare the color differences between the shade guides provided with the products and the actual resin composites before- and after-polymerization. The results obtained from this investigation should provide the clinician with information which may aid in improved color match of esthetic restoration. Five light activated, resin-based materials (${\AE}$litefil, Amelogen Universal, Spectrum TPH VeridonFil-Photo, and Z100) and shade guides were used in this study. Three specimens of each material and shade combination were made. Each material was condensed inside a 1.5mm thick metal mold with 10mm diameter and pressed between glass plates. Each material was measured immediately before polymerization, and polymerized with Curing Light XL 3000 (3M Dental products, USA) visible light-activation unit for 60 seconds at each side. The specimens were then polished sequentially on wet sandpaper. Shade guides were ground with polishing stones and rubber points (Shofu) to a thickness of approximately 1.5mm. Color characteristics were performed with a spectrophotometer (CM-3500d, Minolta Co., LTD). A computer-controlled spectrophotometer was used to determine CIELAB coordinates ($L^*$, $a^*$ and $b^*$) of each specimen and shade guide. The CIELAB measurements made it possible to evaluate the amount of the color difference values (${\Delta}E{^*}ab$) of resin composites before the polymerization process and shade guides using the post-polishing color of the composite as a control, CIE standard D65 was used as the light source. The results were as follows. 1. Each of the resin composites evaluated showed significant color changes during light-curing process. All the resin composites evaluated except all the tested shades of 2100 showed unacceptable level of color changes (${\Delta}E{^*}ab$ greater than 3.3) between pre-polymerization and post-polishing state. 2. Color differences between most of the resin composites tested and their corresponding shade guides were acceptable but those between C2 shade of ${\AE}$litefil and IE shade of Amelogen Universal and their respective shade guides exceeded what is acceptable. 3. Comparison of the mean ${\Delta}E{^*}ab$ values of materials revealed that Z100 showed the least overall color change between pre-polymerization and post-polishing state followed by ${\AE}$litefil, VeridonFil-Photo, Spectrum TPH, and Amelogen Universal in the order of increasing change and Amelogen Universal. Spectrum TPH, 2100, VeridonFil-Photo and ${\AE}$litefil for the color differences between actual resin and shade guide. 4. In the clinical environment, the shade guide is the better choice than the shade of the actual resin before polymerization when matching colors. But, it is recommended that custom shade guides be made from resin material itself for better color matching.

• 대한소아치과학회지
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• 제50권1호
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• pp.65-74
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• 2023

본 연구는 "Smart chromatic technology"를 기반으로 새롭게 개발된 복합 레진인 Omnichroma의 폴리싱 이후 표면 거칠기와 우식원성 미생물 부착을 서로 다른 필러 조성을 가진 기존의 2가지 복합 레진과 비교 평가하였다. 세 종류의 복합 레진: Omnichroma (nano-spherical), Filtek Z350XT (nano-fill), Tetric N-Ceram(nanohybrid)을 사용하여 한 군 당 48개, 총 144개의 시편을 디스크 형태로 제작한 후, 텅스텐 카바이드 버를 이용하여 피니싱 처리하였다. 이후 대조군과 SofLex 디스크, PoGo 버에 따른 3가지 하위군으로 분류하였다. 표면 관찰은 원자 힘 현미경과 주사 전자 현미경을 이용하여 정량적, 정성적으로 분석하였다. 우식원성 미생물 부착은 Streptococcus mutans를 시편에 24시간 배양 후 표면에 부착한 집락 형성 단위를 측정하여 평가하였다. Omnichroma는 피니싱 처리만으로도 매끄러운 표면을 얻을 수 있었으며, 다른 두 가지 복합 레진보다 유의하게 낮은 표면 거칠기를 보였다. 그러나, 폴리싱 후에는 연마 방법과 상관없이 세 종류의 복합 레진의 표면 거칠기 사이에 유의한 차이가 없었다. 세 종류의 복합 레진 모두에서 SofLex 하위군은 대조 하위군에 비해 훨씬 매끄러운 표면을 나타냈다. 그러나, Tetric N-Ceram을 제외한 다른 두 복합 레진에서 대조 하위군과 PoGo 하위군의 표면 거칠기는 통계적으로 유의한 차이가 없었다. 미생물 부착은 세 종류의 복합 레진 각각의 하위군 사이에서 유의한 차이가 없었다. 그러나, Omnichroma는 다른 두 종류의 복합 레진에 비해 전반적으로 더 높은 미생물 부착을 보였다.

• 한국표면공학회지
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• 제37권5호
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• pp.249-252
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• 2004

Effects of HA and TiN coating on the electrochemical characteristics of Ti-6AI-4V alloys for bone plates were investigated using various test methods. Ti-6AI-4V alloys were fabricated by using a vacuum induction furnace and bone plates were made by laser cutting and polishing. HA was made of extracted tooth sintered and then tooth ash was used as HA coating target. The TiN and HA film coating on the surface were carried on using electron-beam physical vapor deposition (EB-PVD) method. The corrosion behaviors of the samples were examined through potentiodynamic method in 0.9% NaCI solutions at $36.5\pm$$1^{\circ}C$ and corrosion surface was observed using SEM and XPS. The surface roughness of TiN coated bone plates was lower than that of tooth ash coated plates. The structure of TiN coated layer showed the columnar structure and tooth ash coated layer showed equiaxed and anisotrophic structure. The corrosion potential of the TiN coated specimen is comparatively high. The active current density of TiN and tooth ash coated alloy showed the range of about $1.0xl0^{-5}$ $A\textrm{cm}^2$, whereas that of the non-coated alloy was$ 1.0xl0^{-4}$ $A\textrm{cm}^2$. The active current densities of HA and TiN coated bone plates were smaller than that of non-coated bone plates in 0.9% NaCl solution. The pitting potential of TiN and HA coated alloy is more drastically increased than that of the non-coated alloy. The pit number and pit size of TiN and HA coated alloy decreased in compared with those of non-coated alloy. For the coated samples, corrosion resistance increased in the order of TiN coated, tooth ash coated, and non-coated alloy.

• 한국식품과학회지
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• 제15권2호
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• pp.160-163
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• 1983

1. ${\alpha}$화 보리쌀의 끓는 물중에서의 수분흡수율은 호화도의 증가에 따라 증가하는 경향이며, 열탕처리구에서 현저하게 증가하고 가압솥처리구에서 가장 낮았으나 모두 무처리구 보다는 증가하였다. 2. ${\alpha}$화 보리쌀로 취반하고 그의 물성을 측정한 결과, 경도는 정백도가 높을수록 낮았으며, 가압솥 처리구가 가장 낮았고, 무처리구는 모두 높았다. 3. ${\alpha}$화 보리쌀 20%와 쌀 80%로 혼합취반하여 관능 검사한 결과 질감은 S-60에서 현저히 높았고 색깔에서는 모든 ${\alpha}$화 시료가 낮게 평가되었으나 총점에서는 무처리구와 유의적인 차이가 없었다.

• 한국세라믹학회지
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• 제46권3호
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• pp.288-294
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• 2009

The platelet AlO(OH) nano colloids were prepared by hydrothermal reaction of the $\gamma-Al_2O_3$ obtained with dehydration of $\gamma$-AlO(OH) and dilute $CH_3COOH$ solution. In hydrothermal reaction process, reversible reaction was accompanied between $\gamma-Al_2O_3$ and AlO(OH), and hydrothermal reaction temperature, hydrothermal reaction time and $CH_3COOH$ concentration had an effect on the crystal structure, surface chemical property, surface area, pore characteristics and crystal morphology of the AlO(OH) nano colloid particles. In this study, it was investigated to the hydrothermal reaction condition of the AlO(OH) nano colloid for using catalyst support, heat resisting agent, adsorbents, binder, polishing agent and coating agent. The crystal structure, surface area, pore volume and pore size of the platelet AlO(OH) nano colloids were investigated by XRD, TEM, TG/DTA, FT-IR and $N_2$ BET method in liquid nitrogen temperature.

• Tribology and Lubricants
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• 제23권6호
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• pp.298-300
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• 2007

Frictional characteristics of mesoporous $SiO_2$ thin films were evaluated with different pore sizes. The films were manufactured by sol-gel and self-assembly methods to have a porous structure. The pores on the surface may play as the outlet of wear particle and the storage of lubricant so that the surface interactions could be improved. The pores were exposed on the surface by chemical mechanical polishing (CMP) or plasma-etching after forming the porous films. The ball-on-disk tests with mesoporous $SiO_2$ thin films on glass specimen were conducted at sliding speed of 15 rpm and a load of 0.26 N. The results show considerable dependency of friction on pore size of mesoporous $SiO_2$ thin films. The friction coefficient decreased as increasing the pore size. CMP process was very useful to expose the pores on the surface.