• Journal of Electrical Engineering and Technology
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• v.2 no.4
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• pp.532-536
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• 2007

Carbon nanotube (CNT) properties, produced using a magnetic null discharge (MND) plasma production technology, were investigated. We firstly deposited the Fe layer 200 nm in thickness on Si substrate by the magnetic null discharge sputter method at the substrate temperature of $300도C$, and then prepared CNTs on the catalyst layer by using the magnetic null discharge (MND) based CVD method. CNTs were deposited in a gas mixture of CH4 and N2 at a total pressure of 1 Torr by the MND-CVD method. The substrate temperature and the RF power were $650^{\circ}C$ and 600W, respectively. The characterization data indicated that the proposed source could synthesize CNTs even under relatively severe conditions for the magnetic null discharge formation.

• Vacuum Magazine
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• v.2 no.3
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• pp.11-15
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• 2015

Particle characteristics diagnosis system (PCDS) was developed to measure submicron particle characteristics by modulation of particle beam mass spectrometry (PBMS) with scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). It is possible to measure the particle size distribution in real-time, and the shape, composition can be measured in sequence keeping vacuum condition. Apparatus was calibrated by measuring the size classified NaCl particle which generated at atmospheric pressure. After the calibration, particles were sampled from the exhaust line of plasma enhanced chemical vapor deposition (PECVD) process and measured. Result confirms that PCDS is capable for analyzing particles in vacuum condition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.263-268
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• 1998

(100) ZnSe crystals with twin and grain free were grown by vapor transport method. The defect in (100) ZnSe crystals was investigated by FWHM of X-ray Rocking Curve. The growth rate and seed quality are the main parameters of the growth process to obtain the high quality ZnSe crystals. The geometric shape of the grown (100) ZnSe crystal is dependent on the shape of seed, isothermal line in furnace and the growth rate of each surface in crystal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.93-93
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• 2008

This paper presents the Raman scattering characteristics of poly (polycrystalline) 3C-SiC thin films deposited on AlN buffer layer by atmospheric pressure chemical vapor deposition (APCVD) using hexamethyldisilane (MHDS) and carrier gases (Ar + $H_2$).The Raman spectra of SiC films deposited on AlN layer of before and after annealings were investigated according to the growth temperature of 3C-SiC. Two strong Raman peaks, which mean that poly 3C-SiC admixed with nanoparticle graphite, were measured in them. The biaxial stress of poly 3C-SiC/AlN was calculated as 896 MPa from the Raman shifts of 3C-SiC deposited at $1180^{\circ}C$ on AlN of after annealing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.37-39
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• 1996

A hydride vapor phase epitaxy (HVPE) method was performed to prepare the GaN thick-films on c-plane sapphire substrates. The full-width at half maximum of double crystal X-ray rocking curve from 350${\mu}{\textrm}{m}$ thick GaN was 576 arcsecond. The photo- luminescence spectrum measured (at room temperature) show the narrow bound exciton(I$_2$) line and weak donor-acceptor pair recombination peak, however, there was not observed deep donor-acceptor pare recombination indicate the GaN crystals prepared in this study are of high purity and high crystalline quality.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.6
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• pp.326-332
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• 2009

The purpose of the study is to decrease the refrigerant temperature at the outlet of the compressor under high thermal load conditions for air cooled vapor compression refrigeration system. The subcooling bypass line called subcooling bypass technology(SBT) is installed to the window type A/C system to investigate the performance test. The standard air calorimeter test method is applied to measure the refrigerant temperature at the outlet of the compressor, cooling capacity, power consumption, and system EER. The refrigerant temperature at the outlet of the compressor decreases as the bypass rate increases. When the bypass rate is 8.2%, the refrigerant temperature at the outlet of the compressor decreases $2.8^{\circ}C$ while the cooling capacity and EER are the same as the conventional A/C unit.

• Corrosion Science and Technology
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• v.4 no.1
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• pp.33-38
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• 2005

Some feasibility studies are conducted to produce an advanced ceramic coating, which reveals superior chemical and mechanical strength, on metal base structure used in chemical plant. This advanced coating on metallic frame can replace ceramic delivery pipe and reaction chamber used in chemical plant, which are operated in hi-temperature and corrosive/erosive environment. An dual spraying is adopted to reduce the residual stress in order to increase the coating thickness and the residual stress is estimated by in-situ manner. Then new methodology is tried to form special coating of yttrium aluminum garnet(YAG), which reveals hi-strength and low-creep rates at hi-temperature, superior anti-corrosion property, hi-stability against Alkali-Vapor corrosion, and so on, on iron base structure. To verify the formation of YAG during thermal spraying, XRD(X ray diffraction) technique was used.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1225-1230
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• 2004

In this paper, the pressure drops were investigated according to the sintered porous wick structure in loop heat pipe(LHP) by theoretical analysis. LHP has the wick only in evaporator for the circulation of working fluid, so utilizes porous wick structure which pore diameter is very small for large capillary force. This paper investigates the effects of different parameters on the pressure drops of the LHP such as particle diameter of sintered porous wick, wick porosity, vapor line diameter, thickness of wick and heating capacity. Working fluid is water and the material of sintered porous wick is copper. According to the these different parameters, capillary pressure, pressure drop in wick were analized by theoretical design method of LHP.

• Journal of the Korean Ceramic Society
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• v.37 no.4
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• pp.376-380
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• 2000

Carbon nanofibers with an average diameter of 100nm were reacted with SiO vapor generated from a mixture of Si and SiO2 to produce silicon carbide nanofibers at temperature ranging 1200∼1500$^{\circ}C$ under vacuum. The nanofiber reacted at 1200$^{\circ}C$ for two hours consisted of silicon carbide with an average crystallite size of 10-20nm, amorphous silica and a significant amount of unreacted carbon. The surface area of silicon carbide nanofiber, obtained after removal of amorphous silica and unreacted carbon from converted carbon nanofibers at 1200$^{\circ}C$, was as high as 150㎡/g. With increasing reaction temperature to 1500$^{\circ}C$, the surface area was decreased to 14㎡/g. Growth of SiC crystallite size with increasing conversion temperature of carbon nanofiber was confirmed from Scherrer formula using the (111) diffraction line and TEM images of converted carbon nanofibers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.194-197
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• 1997

A hydride vapor phase epitaxy (HVPE) method was performed to prepare the thick-fi lm GaN on AIN/Si substrates. We obtained substrate-free GaN. The foul t-width at half maximum of double crystal X-ray rocking curve from 350 ${\mu}{\textrm}{m}$ thick substrate-free GaN was ~1000 arcsec. The photoluminescence spectrum (at 20 K) shows the narrow bound exiton (I$_2$) line and wealth donor-acceptor pair recombination however. there was not observed deep donor-accepter pair recombination indicate the substrate-free GaN crystal prepared in this study are of high purity and high crystalline quality.