• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.85-90
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• 2003

Removal rate and Within Wafer Non-Uniformity (WIWNU), the most critical issues in Chemical Mechanical Polish (CMP) process, are related to the pressure distribution, wafer shape, slurry flow, mechanical property of pad and etc. Among them, wafer warp generated by other various manufacturing process of wafer may induce the deviation of pressure distribution on the backside of wafer. In the convex shaped wafer the pressure onto the backside of wafer is higher than that of perfectly flat shaped wafer. Besides, such an added pressure is in proportion to the curvature of wafer. That is, the bigger the curvature of wafer becomes the higher the removal rate goes. And the WIWNU is known to be directly related to the pressure distribution on the wafer as well. In other words, the deviation of pressure distribution is in proportion to the WIWNU. In this paper, it is found that the wafer shape may be modified through heating the backside of it and thus properly changed pressure onto the backside of it may improve the WIWNU.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.2
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• pp.92-99
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• 2018

A numerical analysis of a compressor dehumidifier has been conducted focusing on the air side heat transfer, which is a part of a series research on the dehumidifier. The moving reference frame was applied to the fan modeling, and the porous model was used for the evaporator and condenser modeling. Curve fitting obtained the inertial and viscous resistances parameters to the results of the physical model of the unit cell with actual shape of a fin tube. The porous model was validated within a reasonable computation time for the range of practical inlet velocity of a dehumidifier. A parametric study has been conducted for fin number, fan speed (i.e., air flow rate), and evaporator/condenser tube arrangement. ANOVA analysis showed the dependency of each parameter on the velocity and temperature uniformity, which are desirable for high performance of the dehumidifier.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.4
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• pp.268-273
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• 2000

Plasma models are crucial to equipment design and process optimization. A radial basis function network(RBFN) in con-junction with statistical experimental design has been used to model a process plasma. A 2$^4$ full factorial experiment was employed to characterized a hemispherical inductively coupled plasma(HICP) in characterizing HICP, the factors that were varied in the design include source power, pressure, position of shuck holder, and Cl$_2$ flow rate. Using a Langmuir probe, plasma attributes were collected, which include typical electron density, electron temperature. and plasma potential as well as their spatial uniformity. Root mean-squared prediction errors of RBEN are 0.409(10(sup)12/㎤), 0.277(eV), and 0.699(V), for electron density, electron temperature, and Plasma potential, respectively. For spatial uniformity data, they are 2.623(10(sup)12/㎤), 5.704(eV) and 3.481(V), for electron density, electron temperature, and plasma potential, respectively. Comparisons with generalized regression neural network(GRNN) revealed an improved prediction accuracy of RBFN as well as a comparable performance between GRNN and statistical response surface model. Both RBEN and GRNN, however, experienced difficulties in generalizing training data with smaller standard deviation.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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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.

• Progress in Superconductivity
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• v.7 no.2
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• pp.174-178
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• 2006

For the practical application on SCFCL, Bi2212 tubes were fabricated by Centrifugal Forming Process (CFP) in terms of many different processing parameters. Typical sizes of tubes were 60, 150 mm in length and 2.5, 3.5, 4.8 mm in thickness. Initially powder was melted by induction heating. The optimum range of melting temperatures and preheating temperature were $1100^{\circ}C$ and $500^{\circ}C$ for 30min respectively. The nominal mold rotating speed was around 1000 RPM. A tube was annealed at $840^{\circ}C$ for 80 hours in oxygen atmosphere. The tube of 50mm x 70mm x 2.5mm, rotated with 1000 RPM showed $I_c=890\;A\;and\;T_c=80$. It was found that the tube processed with faster rate of mold rotation speed, thinner tube thickness and shorter tube length shows better electric characteristics as compared with the tube normally processed. In order to study the uniformity heat and fluid flow analysis tool was adopted along tube.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.3
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• pp.157-168
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• 1993

Pipe network of hot water heat supply system in an apartment house was analyzed. Flowrate and supply heat capacity of each household in which constant flowrate balancing valve is installed in a single zone system were calculated and the results were investigated. In the existing piping system, the non-uniformity of heat supply with floors due to the static pressure and temperature difference between supply main and return main can not be avoided and this tendency get intense with the increase of the height of building. The non-uniformity of heat supply can be prevented by the installation of balancing valve at each household, however if the performance of supply pump is not sufficient to overcome the energy loss due to the installation of balancing valve for constant flow rate or if the selection of the valve capacity is not adequate, the valves will may lose their controllability.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.2
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• pp.86-95
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• 2023

This paper explained the equipment and process development to secure the source technology of controlled nitrification technology. The nitriding potential in the furnace was controlled only by adjusting the flow rate of ammonia gas introduced into the furnace. In addition, a control system was introduced to automate the nitriding process. The equipment's hardware was designed to enable controlled nitriding based on the conventional gas nitriding furnace, and an automation device was attached. As a result of measuring the temperature and quality uniformity for the equipment, the temperature and compound uniformity were ±1.2℃ and 14.3 ± 0.2 ㎛, respectively. And, it was confirmed that nitriding potential was controlled within the tolerance range of AMS2759-10B standard. In addition to parts for controlled nitriding, it was applied to products produced in existing conventional nitriding furnaces, and as a result, gas consumption was reduced by up to 80%.

• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.543-552
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• 1987

The effects of deposition variables on SnO2 CVD were investigated for SnCl4＋O2 reaction at 300∼700$^{\circ}C$, Psncl4=1${\times}$10-5∼1${\times}$10-3 atm, and Po2=5${\times}$10-4∼1 atm. A thermodynamic equilibrium study on Sn-Cl-O system has been performed with the computer calculation. The calculation indicates that major species participating the reaction in SnCl4 and not intermediate species, SnCl2. Good uniformity of the film thickness was obtained at the flow rate of 11cm/sec, which resulted from the stable gas flow in our cold wall reactor. The experimental results showed that apparent activation energy of the deposition was about 13.5Kcal/mole below the temperature of 500$^{\circ}C$ and the deposition mechanism was controlled by surface reation. The behavior of deposition rate on the reactant partial pressures could be explained with the Langmuri-Hinshelwood mechanism. X-ray study demonstrated that SnO2 film deposited at temperatures above 400$^{\circ}C$ were polycrystalline with tetragonal rutile structure and grew with (211) and (301) preferred orientations.

• YAKHAK HOEJI
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• v.34 no.3
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• pp.161-165
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• 1990

An automated, simple, and reliable method was developed for determining in vitro drug release rate from transdermal delivery dosage forms. The patch is held in position in the heating block by sandwiching it between the middle plate and the bottom plate of diffusion cell. The dissolution profile of the commercially available transdermal scopolamine patch was determined over a 72-h period, and the results were compared with those obtained with other methods; paddle-over-disk method, reciprocating method, and diffusion cell method. It was demonstrated that the flow-through method is equivalent in terms of release rate profile and accumulated released drug amount over the lifetime of the dosage form tested. Also this method is simple, reliable and reproducible. Therefore, this technique can be used in a quality control for assuring product uniformity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.3 s.234
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• pp.330-339
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• 2005

An experimental study on the behavior of droplets impinging on a solid flat surface was carried out in the present study. Breakup of a liquid droplet impinging on a solid surface has been investigated experimentally for various liquids with different properties. The liquid droplet temperature and incident angle were chosen as major parameters. Liquid droplet temperature and incident angle varied in the range from $-20{\circ}C\;to\;30{\circ}C\;and\;from\;30{\circ}\;to\;60{\circ},$ respectively. It was found that the variation of droplet temperature influences upon the mean diameter and uniformity of droplets which were bounced out from the solid surface. With increase of incident angle the dispersion mass fraction increases, causing the decrease of liquid film flow rate. As the liquid temperature increases, dispersion mass fraction increases since the surface tension decreases.