• Tribology and Lubricants
• /
• 제32권2호
• /
• pp.67-71
• /
• 2016

This study investigates the characteristics of the sapphire wafer chemical mechanical polishing (CMP) process. The material removal rate is one of the most important factors since it has a significant impact on the production efficiency of a sapphire wafer. Some of the factors affecting the material removal rate include the pressure, platen speed and slurry. Among the factors affecting the CMP process, we analyzed the trends in the material removal rate and surface roughness, which are mechanical factors corresponding to both the pressure and platen speed, were analyzed. We also analyzed the increase in the material removal rate, which is proportional to the pressure and platen speed, using the Preston equation. In the experiment, after polishing a 4-inch sapphire wafer with increasing pressure and platen speed, we confirmed the material removal rate via thickness measurements. Further, surface roughness measurements of the sapphire wafer were performed using atomic force microscopy (AFM) equipment. Using the measurement results, we analyzed the trends in the surface roughness with the increase in material removal rate. In addition, the experimental results, confirmed that the material removal rate increases in proportion to the pressure and platen speed. However, the results showed no association between the material removal rate and surface roughness. The surface roughness after the CMP process showed a largely consistent trend. This study demonstrates the possibility to improve the production efficiency of sapphire wafer while maintaining stable quality via mechanical factors associated with the CMP process.

• 대한가정학회지
• /
• 제23권1호
• /
• pp.19-24
• /
• 1985

The effect of temperature, washing time, mechanical agitation and concentration on the removal from cotton fabrics of tripalmitin labelled with C\sup 14\ were studied. In order to correlate the detergency with the removal mechanism, solubilization and suspending power of surfactants were observed. RESULTS : 1. The detergency from cotton fabric was increased with elevating temperature and over the temperature of maximum detergency, the rate of soil removal was rather decreased. 2. The effects of washing time and mechanical agitation on the removal of triplamitin were obvious at lower temperature. 3. The removal of tripalmitin was remarkably increased at higher concentration over cmc for all surfactants. The detergency of nonionic surfactant -NPPG- was best, this was resulted from its large solubilization and suspending power.

• Tribology and Lubricants
• /
• 제33권5호
• /
• pp.228-233
• /
• 2017

Chemical Mechanical Polishing of chemically stable sapphire substrates is dominantly affected by the mechanical processing of abrasives, in terms of the material removal rate. In this study, we investigated the effect of electrostatic force between the abrasives and substrate, on the polishing. If potassium chloride (KCl) is added to slurry, water molecules are decomposed into $H^+$ and $OH^-$ ions, and the amount of ions in the slurry changes. The zeta potential of the abrasives decreases with an increase in the amount of $H^+$ ions in the stern layer; consequently, the electrostatic force between the abrasives and substrate decreases. The change in zeta potential of abrasives in the slurry is affected by the slurry pH. In acidic zones, the amount of ions bound to the abrasives increases if the amount of $H^+$ ions is increased by adding KCl. However, in basic zones, there is no change in the corresponding amount. In acidic zones, zeta potential decreases as molar concentration of potassium increases; however, it does not change significantly in basic zones. The removal rate tends to decrease with increase in molar amount of potassium in acidic zones, where zeta potential changes significantly. However, in basic zones, the removal rate does not change with zeta potential. The tendencies of zeta potential and that of the frictional force generated during polishing show strong correlation. Through experiments, it is confirmed that the contact probability of abrasives changes according to the electrostatic force generated between the abrasives and substrate, and variation in removal rate.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.1655-1659
• /
• 2008

Using numerical models, we investigated the efficiency of toxin removal using pulsatile flow in blood purification systems that use semipermeable membranes. The model consisted of a three-compartmental mass transfer model for the inside body and a solute kinetics model for the dialyzer. The model predicted the toxin concentration inside the body during blood purification therapy, and the toxin removal efficiencies at different flow configurations were compared quantitatively. According to the simulation results, the clearances of urea and ${\beta}_2$ microglobulin (B2M) using a pulsatile pump were improved by up to 30.9% for hemofiltration, with a 2.0% higher urea clearance and 4.6% higher B2M clearance for high flux dialysis, and a 3.9% higher urea clearance and 8.2% higher B2M clearance for hemodiafiltration. These results suggest that using a pulsatile blood pump in blood purification systems with a semipermeable membrane improves the efficacy of toxin removal, especially for large molecules and hemofiltration treatment.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.664-667
• /
• 2008

Since the advent of pedicle screw fixation system, posterior spinal fusion has markedly increased This intemal fixation system has been reported to enhance the fusion rates, thereby becoming very popular procedure in posterior spinal arthrodesis. Although some previous studies have shown the complications of spinal instruments removal, i.e. loss of correction and spinal collapse in scoliosis or long spine fusion patients, there has been no study describing the benefit or complications in lumbar spinal fusion surgery of one or two level. In order to clarify the effect of removal of instruments on mechanical motion profile, we simulated a finite element model of instrumented posterolateral fused lumbar spine model, and investigated the change of mechanical motion profiles after the removal of instrumentation.

• International Journal of Automotive Technology
• /
• 제7권2호
• /
• pp.121-128
• /
• 2006

The interaction between adherent molecules and gas molecules was modeled in the molecular scale and simulated by the molecular dynamics method in order to understand evaporation and removal processes of adherent molecules on metallic surface using high temperature gas flow. Methanol molecules were chosen as adherent molecules to investigate effects of adhesion quantity and gas molecular collisions because the industrial oil has too complex structures of fatty acid. Effects of adherent quantity, gas temperature, surface temperature and adhesion strength for the evaporation rate of adherent molecules and the molecular removal mechanism were investigated and discussed in the present study. Evaporation and removal rates of adherent molecules from metallic surface calculated by the molecular dynamics method showed the similar dependence on the surface temperature shown in the experimental results.

• 한국전기전자재료학회논문지
• /
• 제17권2호
• /
• pp.156-161
• /
• 2004

We investigated the effects of oxidizer additive on the performance of Cu-CMP process using commonly used tungsten slurry. In order to compare the removal rate and non-uniformity as a function of oxidizer contents, we used alumina-based tungsten slurry and copper blanket wafers deposited by DC sputtering method. According to the CMP removal rates and particle size distribution, and the microstructures of surface layer by SEM image as a function or oxidizer contents were greatly influenced by the slurry chemical composition of oxidizers. The difference in removal rate and roughness of copper surface are believed to cause by modification in the mechanical behavior of $Al_2$O$_3$abrasive particles in CMP slurry.

• 한국전기전자재료학회논문지
• /
• 제20권4호
• /
• pp.303-307
• /
• 2007

This paper investigated the effect of the pad buffing process on the material removal characteristics and pad stabilization during silicon chemical mechanical polishing. The pads surface were controlled by the buffing process using a buffer made by the sandpaper. The buffing process is based on abrasive machining by using a high speed sandpaper. The controlled pad by the buffing process show less deformation deviation and stable material removal rate during the CMP process. In addition, the controlled pad ensure better uniformity of removal rate than comparative pads. As a result of monitoring, the controlled pad by the buffing process demonstrated constant and stable friction force signals from initial polishing stage. Therefore, the tufting process could control the pad surface to be uniform and improve the performance of the polishing pad.

• Journal of the Korean Wood Science and Technology
• /
• 제38권1호
• /
• pp.27-35
• /
• 2010

본 연구에서는 국내에서 생산 유통되고 있는 시판용 목탄(전통숯, 기계숯)의 기본물성과 흡착특성을 알아보기 위해 탄화물의 공업분석, 세공분석, 메틸렌블루 흡착량, 포름알데히드 제거율, 에틸렌가스 제거율 등을 분석하였다. 고정탄소는 전통숯의 흑탄이 51.8~76.6%, 백탄이 72.9~84.6%, 기계숯이 48.5~80.3%로 백탄이 높은 것으로 나타났다. 정련도는 흑탄의 경우 대부분 9였고, 백탄과 기계숯은 0으로 나타났다. 비표면적은 흑탄이 0.1~13.7 $m^2/g$, 백탄이 53.2~372.6 $m^2/g$, 기계숯이 224.3~464.6 $m^2/g$로 흑탄이 가장 낮은 것으로 나타났다. 메틸렌블루 흡착량은 흑탄이 0.53~1.97 mg/g, 백탄이 2.68~7.68 mg/g, 기계숯이 11.63~26.10 mg/g 범위로 흑탄이 아주 낮은 경향을 나타냈다. 포름알데히드 제거율은 흑탄이 11.4~26.7%, 백탄이 17.9~34.9%, 기계숯이 5.5~25.8% 범위로, 큰 차이를 나타내지 않았다. 에틸렌가스 제거율은 흑탄이 2.2~43.5%, 백탄이 21.7~39.1%, 기계숯이 21.7~39.1% 범위로, 큰 차이를 나타내지 않았다.

• 한국임상수의학회지
• /
• 제30권1호
• /
• pp.36-40
• /
• 2013

Caval syndrome은 감염된 다수의 심장사상충이 우심방, 우심실을 포함한 우심계와 대정맥으로 이동하여 삼첨판의 움직임을 물리적으로 방해하고 폐동맥으로 가는 혈류의 장애를 유발하여 생명을 위협하는 질환이다. 이 질환의 치료를 위해 외과적인 사상충의 제거가 필요하다. 본 증례는 modified extraction brushes를 이용한 새로운 방법의 심장사상충 제거 방법에 대한 보고이다. 본 연구에서 새롭게 만들어진 사상충 제거 카테터를 사용하여 caval syndrome에 감염된 두 마리의 개를 성공적으로 치료하였다. 비록 새로운 시술법의 적용이 단지 두 증례에 불과하지만, 본 시술법은 심장 사상충 치료를 위한 외과적 제거방법 중 하나로 선택할 수 있다.