• Journal of computational fluids engineering
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• v.21 no.2
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• pp.54-61
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• 2016

When spent fuel assemblies from the reactor of nuclear power plants(NPPs) are transported, the assemblies are exposed to short-term operations that can affect the peak cladding temperature of spent fuel assemblies. Therefore, it needs to perform the analysis of heat transfer on spent fuel dry cask during the operation. For 3 dimensional computational fluid dynamnics(CFD) simulation, it is proposed that the short-term operation is divided into three processes: Wet, dry, and vacuum drying condition. The three processes have different heat transfer mode and medium. Metal transportation cask, which is Korea Radioactive Waste Agency(KORAD)'s developing cask, is evaluated by the methods proposed in this work. During working hours, the boiling at wet process does not occur in the cask and the peak cladding temperatures of all processes remain below $400^{\circ}C$. The maximum peak cladding temperature is $173.8^{\circ}C$ at vacuum drying process and the temperature rise of dry, and vacuum drying process occurs steeply.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.91-96
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• 2013

The present paper focuses on the fabrication of materials with higher thermal conductivity. Nanofluid is a novel transfer prepared by dispersing nanometer-sized solid particles in traditional heat transfer fluid to increase thermal conductivity and heat transfer performance. The purpose of this study is making the nano-size particle. The experiment of MWCNT and $Al_2O_3$ was carried out using a planetary ball mill at several rotation speeds: 200 ~ 400 rpm. The results were examined using scanning electron microscope(SEM). In the case of the MWCNT, it could be more grinding into the small particle in the dry condition and it confirm in the case of the $Al_2O_3$ to be more grinding into the small particle contrary to the MWCNT in the wet condition. In the mixture grinding result of MWCNT and $Al_2O_3$, the dry condition showed the good result in low rotation speed than the wet condition.

• Composites Research
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• v.24 no.5
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• pp.34-38
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• 2011

Carbon nanotubes (CNTs) have been widely investigated as reinforcements of CNT/polymer nanocomposites to enhance mechanical and electrical properties of polymer matrices since their discovery in the early 90's. Furthermore, the number of studies about incorporating CNTs into carbon fiber reinforced plastics (CFRP) to reinforce their polymer matrices is increasing recently. In this study, single-walled carbon nanotubes (SWNT) were dispersed in epoxy with 0.2 wt.% and 0.5 wt.%. Then, the SWNT/epoxy mixtures were processed to carbon fiber composites by a vacuum assisted resin transfer molding (VARTM) and a wet lay up method. The processed composite samples were tested for the interlaminar shear strength (ILSS). The relationship between the interlaminar shear strengths and processing, and the reinforcement mechanism of carbon nanotubes were investigated. CNT/epoxy nanocomposite specimens showed the increased tensile properties. However, the ILSS of carbon fiber composites was not enhanced by reinforcing the matrix with CNTs because of processing issues caused by increased viscosity of the matrix due to addition of CNTs particularly for a VARTM method.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.62-64
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• 2015

We have investigated zinc tin oxide (ZTO) thin films under various silicon ratios. ZTO TFTs were fabricated by solution processing with the bottom gate structure. Furthermore, annealing process was performed at different temperatures in various annealing conditions, such as air, vacuum and wet ambient. Completed fabrication of ZTO TFT, and the performance of TFT has been compared depending on the annealing conditions by measuring the transfer curve. In addition, structure in ZTO thin films has been investigated by X-ray diffraction spectroscopy (XRD) and Scanning electron microscope (SEM). It is confirmed that the electrical performance of ZTO TFTs are improved by adopting optimized annealing conditions. Optimized annealing condition has been found for obtaining high mobility.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.05a
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• pp.157-162
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• 2005

The wafer's size has been increased up to 300mm according as the devices have been integrated sophisticatedly. For this process to make 300mm-wafer, it is required strict level which removes the particulates on the surface of wafer. Therefore we need new type wet-station which can reduce DI water and chemical in the cleaning process. Moreover, it is very important to control the temperature and the concentration of chemical wet-stat ion. The chemical supply system which is used currently is not only difficult to make a fit mixing rate of chemical in cleaning process, but also it is difficult to make fit quantity and temperature. We propose new chemical supply system, which overcomes the problems via analysis of fluid and thermal transfer on chemical supply system,

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.22-28
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• 2001

Heat transfer and pressure distribution for heat exchanger type of domestic gas boiler are different from shape, pitch, thickness of fin and array of pipe respectively. In order to measure the pressure distribution across the heat exchanger, a suction type wind tunnel was constructed and velocity distribution was measured for pilot tube(4 point) of rack type. The experiments were performed for 5 different air flow mass, rpm=3,6,9,12,15 and transverse axis of heat exchanger(x-length) is 5cm respectively. Results showed that above 9.5m/s, pressure distribution dispersion for wet type of heat exchanger is on the increase and above 5.5m/s, pressure distribution dispersion for dry type of heat exchanger is on the increase. Also, pressure distribution dispersion by comparing two different types heat exchanger, dry type of heat exchanger showed a higher augmentation than wet type of heat exchanger.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.123-128
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• 2004

Semiconductor Wet Station has a very important place in semiconductor process. It is important that to discharge chemical with fit concentration and temperature using chemical supply system for clean process. The chemical supply system which is used currently is not only difficult to make a fit mixing rate of chemical which is need in clean process, but also difficult to make fit concentration and temperature. Moreover, it has high stability but it is inefficient spatially because its volume is great. We propose In-line System to improve system with implement analysis of fluid and thermal transfer on chemical supply system and understand problem of system.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.1
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• pp.62-67
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• 2016

This paper presents a silicon nanostructure array embedded in a polymer film. The silicon nanostructure array was fabricated by using basic microelectromechanical systems (MEMS) processes such as photolithography, reactive ion etching, and anisotropic KOH wet etching. The fabricated silicon nanostructure array was transferred into polymer substrates such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polycarbonate (PC) through the hot-embossing process. In order to determine the transfer conditions under which the silicon nanostructures do not fracture, hot-embossing experiments were performed at various temperatures, pressures, and pressing times. Transfer was successfully achieved with a pressure of 1 MPa and a temperature higher than the transition temperature for the three types of polymer substrates. The transferred silicon nanostructure array was electrically evaluated through measurements with a semiconductor parameter analyzer (SPA).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1766-1775
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• 2001

A theoretical analysis on the heat and mass transfer in an evaporative cooler is presented in this work. The evaporative cooler is modeled as a channel filled with porous media the interstitial surface of which is covered by thin water film. Assuming that the Lewis number is unity and the water vapor saturation curve is linear, exact solutions to the energy and vapor concentration equations are obtained. Based on the exact solutions, the characteristics of the heat and mass transfer in the evaporative cooler are investigated. The comparison of the cooling performance between the evaporative cooler and the usual sensible heat exchanger is also carried out. Obviously, the evaporative heat exchanger shows better cooling performance than the sensible heat exchanger. This is due to the latent heat of water vaporization, which results in apparent increases both in the interstitial heat transfer coefficient and the specific heat of the air stream in the evaporative cooler.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.597-602
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• 2008

The experiment of performance about closed-wet cooling tower(CWCT) was conducted in this study. The test section has the cooling water that flows from top part of a heat exchanger that has an entrance of cooling water with one and multi path. The heat exchanger consists of 15.88mm tubes with ten rows and ten columns and staggered arrangement. In this experiment, heat and mass transfer coefficients and range are calculated with variations of cooling water and path. The results indicated that operating CWCT using two path have the high values of heat and mass transfer coefficients and range than one path.