• 한국정밀공학회지
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• 제19권10호
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• pp.212-220
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• 2002

The finishing process for die and mold manufacturing is very important because it influences the final quality of products. Injection molds need higher quality surface than general purpose dies and molds. Conventional polishing can not make mold surface down to nanometer roughness efficiently because of their loading and glazing. This paper focused on the development of fixed abrasive pad using water swelling mechanism of polymer binder network. Self-conditioning was recognized as the long term polishing stabilization tool without any loading or glazing because water makes fixed abrasives free by swelling of the pad. Consequently, stable nano-polishing process has been applied on the injection mold, from the experimental results with polished surface roughness of Ra 15.1nm on STD-11 die steel.

• Tribology and Lubricants
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• 제30권5호
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• pp.265-270
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• 2014

Frictional heat greatly influences the friction behaviors during clutch engagement. Therefore, the engagement of a wet or dry clutch is frequently not under control by the frictional heat. In a wet clutch, the frictional temperature also specially needs to be controlled, and in many cases, the clutch material is selected to prevent a temperature rise from the friction between friction pad and separator. However, only the selection of the clutch material cannot ensure sufficient control of the temperature rise by the friction. The groove pattern on a friction pad is designed for more flow rates of transmission fluid between the contact gap of clutch pad and separator for the cooling effect. In this work, grove patterns are designed for more flow rates out of the contact gap between friction pad and separator plate. Selected groove design shows the improvement flow rates of transmission fluid through both inner and outer radius, where most of the transmission fluid flows through the outer radius when the clutch is engaged due to the centrifugal force in conventional wet clutch groove. Several comparisons of the amounts of frictional heat generated on clutch pads are made in order to verify the decrease of the temperature rise according to the flow rates along the groove patterns.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.356-357
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• 2005

Chemical mechanical polishing (CMP) allows the planarization of wafers with two or more materials at their surfaces. Especially, polishing pad is considered as one of the most important consumables because of its properties. Subject of this investigation is to apply CMP for planarization of shallow trench isolation structure using microstructure pad. Microstructure pad is designed to have uniform structure on its surface and fabricated by micro-molding technology. And then STI CMP performances such as oxide dishing and nitride corner rounding are evaluated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.366-367
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• 2005

The effect of benzotriazole (BTA) on the adhesion force of silica and pad particle on Cu/TEOS wafer surfaces was investigated with and without the addition of BTA. Cu-BTA had the isoelectric point (IEP) at around pH 4$\sim$8. Pad particles were more positive zeta potentials than silica. The adhesion force initially decreased of silica and pad particle on Cu surfaces when BTA was added. However, the more BTA was added, the more adhesion force gradually increased with the increase of BTA concentrations. Then the adhesion force of pad particle was higher than silica. And TEOS didn't resulted increasing adhesion force like Cu when BTA was added in DI water.

• Tribology and Lubricants
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• 제30권2호
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• pp.92-98
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• 2014

Transmission fluid film behaviors in the gap between the wet clutch pad and separator plate are analyzed using the CFD software ADINA. Three pattern groove designs are selected and are used to validate the fluid film behaviors based on the outlet flow in the gap when the wet clutch pad and separator plate are engaged. The main design goal for pattern grooves is faster engagement. In most cases, much of the outlet flow of transmission fluid in the gap occurs on the outer radius boundary due to the centrifugal force generated by the clutch pad circular motion. Groove patterns are created to ensure faster transmission fluid outlet flow in the direction of the inner radius boundary. Computational results of the selected groove patterns are compared.

• Tribology and Lubricants
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• 제30권2호
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• pp.77-85
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• 2014

This study set out to predict the load capacity and rotordynamic coefficients of tilting-pad journal bearings, taking the pivot stiffness into account. The analysis uses rocker-back (cylindrical) and ball in socket (spherical) pivot models, both of which are based on Hertzian contact stress theory. The models ascertain the non-linear elastic deformation of the pivots according to the applied load, pivot geometry, and material properties. At present, the Reynolds equation for an isothermal, isoviscous, and incompressible fluid is used to calculate the film pressure by using the finite-element method, after which the Newton-Raphson method is used to simultaneously find the journal center location, pad angles, and pivot deflections. The bearing analysis, excluding the pivot models, is validated using predictions those are readily available in the literature. As the rotor speed increases, the predicted journal eccentricity and damping coefficients decrease, but the stiffness coefficients increase, as expected. Most importantly, the implementation of the pivot models increases the journal eccentricity but significantly decreases the stiffness and damping coefficients of the tilting-pad journal bearings.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.481-482
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• 2006

Chemical-mechanical polishing, the dominant technology for LSI planarization, is trending to play an important function in micro-electro mechanical systems (MEMS). However, MEMS CMP process has a couple of different characteristics in comparison to LSI device CMP since the feature size of MEMS is bigger than that of LSI devices. Preliminary CMP tests are performed to understand material removal rate (MRR) with blanket wafer under a couple of polishing pressure and velocity. Based on the blanket CMP data, this paper focuses on the consumable approach to enhance MEMS CMP by the adjustment of slurry and pad. As a mechanical tool, newly developed microstructured (MS) pad is applied to compare with conventional pad (IC 1400-k Nitta-Haas), which is fabricated by micro melding method of polyurethane. To understand the CMP characteristics in real time, in-situ friction force monitoring system was used. Finally, the topography change of poly-si MEMS structures is compared according to the pattern density, size and shape as polishing time goes on.

• 한국정밀공학회지
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• 제23권5호
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• pp.59-67
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• 2006

Chemical Mechanical Polishing(CMP) in semiconductor production is characterized its output property by Removal Rate(RR) and Non-Uniformity(NU). Some previous works show that RR is determined by production of pressure and velocity and NU is also largely affected by velocity of flowfield during CMP. This study is about the direct measurement of velocity of slurry during CMP and whole flowfield upon the non-groove pad by Particle Image Velocimetry(PIV). Typical PIV system is modified adequately for inspecting CMP and slurry flowfield is measured by changing both pad rpm and carrier rpm. We performed measurement with giving some variation in the kinds of pad. The results show that the flowfield is majorly determined not by Carrier but by Pad in the case of non-groove pad.

• 한국염색가공학회지
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• 제28권3호
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• pp.175-182
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• 2016

To investigate dyeing behaviors in accordance with dye structure in cold pad batch dyeing of cotton knit, monochlorotriazine-vinylsulfone bifunctional dyes and monofluorotriazine-vinylsulfone bifunctional dyes were prepared. The spectral property and solubility of the dyes were tested and compared with the imported dyes. In addition, exhaustion behaviors of individual and mixed dye solutions were measured to examine the influence of dye structure on dyeing behavior in cold pad batch dyeing. The substantivity, fixation, migration index and half dyeing time were also calculated for further analysis of dyeing behavior of the prepared dyes. As a result, both dyes exhibited the superior solubilities and satisfactory light absorption properties. Also, monofluorotriazine-vinylsulfone bifunctional dyes showed moderate sensitivity to alkalinity and proper kinetic index values compared with the monochlorotriazine-vinylsulfone bifunctional dyes and the imported dyes. The results indicated monofluorotriazine-vinylsulfone bifunctional structure of the dye is suitable for cold pad batch dyeing.

• Clinical and Experimental Reproductive Medicine
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• 제23권3호
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• pp.293-301
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• 1996

In the present study, mouse follicular oocytes and 2-cell embryos(late -zygote stage embryos included) were cultured on the electric pad for electric stimulation in the culture incubator. In addition, follicular oocytes and embryos were tested for maturation and development under higher temperature condition($39^{\circ}C$).Mouse follicular oocyte maturation were not affected by anion electric stimulation and there is no significant difference in GBVD and MI between the control and experiment group after 4hr culture. In the embryo culture, it was found that more morula and blastocyst were found in the electric stimulation group rather than the control(96hr). This may seem to be caused with cytoplasmic $Ca^{2+}$ transient rise by electric stimulation(anion pad). On the other hand higher temperature incubation ($39^{\circ}C$) on the anion pad caused all the embryos degenerated within $12h{\sim}24hr$ culture. This was quite different from large animal embryos(bovine, pig, sheep), in which beneficial effect of high temperature incubation for oocyte maturation and embryo development were found.