• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1991.10a
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• pp.7-9
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• 1991

$\prod$-A characteristics of N-docosylquinolium-TCNQ complex were investigated with the following variations. I> $\prod$-A characteristics with a variation of spreading amount. ii> $\prod$-A characteristics with a variation of barrier speed. iii> $\prod$-A characteristics with a variation of subphase temperature. An optimum surface pressure for a deposition of Langmuir-Blodgett(LB) layer was found to be a 40∼50 mN/m in pure water subphase (pH 5.4, $25^{\circ}C$).

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.167-170
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• 2016

Various piezoelectric nanostructures have been extensively studied for competitive energy harvesting applications. Here, GaN nanowires grown by a nonconventional magnetic field-assisted chemical vapor deposition process were investigated to characterize the piezoelectric energy harvesting characteristics. As a controlling parameter, only the growth time was changed from 15 min to 90 min to obtain different crystallinity and morphology of the nanowires. Energy harvesting characteristics were found to depend largely on the growth time. A longer growth time tended to lead to an increased output current, which is reasonable when considering the enhanced charge potentials and crystallinity. A maximum output current of ~14.1 nA was obtained for the 90 min-processed nanowires.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.451-456
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• 2004

The Titanium has many superior characteristics Which are specific strength, heat resistance, corrosion resistance, organism compatibility, non-magnetic and etc. and their quantity are abundant this study performed turning operation of Ti-6Al-4V alloy using the TiAlN Coate Tool which treated PVD (Physical Vapor Deposition). Experimental works are also executed to measure cutting force, chip figuration and surface roughness for different cutting conditions. As a result of study. Tool wear was serious at over 100m/min of cutting speed and cutting condition was excellent at 1.0mm of cutting depth.

• Journal of the Korean Applied Science and Technology
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• v.7 no.1
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• pp.77-80
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• 1990

Using $CdCl_2$ buffer solution as subphase for LB films deposition, it was achieved successively to fabricate the Y-type mixed LB films of (N-eicosyl pyridinium)-TCNQ(1:2) complex and arachidic acid. By measure of U.V spectra and capacitance, deposition status was confirmed. Electrical conductivity was measured on a perpendicular direction of the LB films and in consequence of calculated was average $2.5\;{\times}\;10^{-13}$ - $2\;{\times}\;10^{-14}$ S/cm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.104-108
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• 2015

Al thin films were deposited on TiN/Si(100) via metal-organic chemical vapor deposition using N-methylpyrrolidine alane as a precursor. Characterization of the deposited films were investigated with SEM, XRD, ${\alpha}$-step, AFM, 4-point probe. The early stage of Al thin film deposition was analyzed by in-situ surface reflectance measurement with laser and photometer apparatus. The surface reflectance were changed greatly during the initial 30~40 seconds. There were two increases and two decreases in the surface reflectance, thus the sequence of Al films were deposited at 8 significant points of the surface reflectance change. Surface topograph and cross-sectional view of each film were analyzed with SEM. Al films were grown in the complex mechanism of Volmer-Weber and Stranski-Krastanov process.

• Journal of the Korean institute of surface engineering
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• v.24 no.2
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• pp.73-79
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• 1991

Recent studies son surface coatings have shown that the change of physical, chemical and crystallographic structure analysed and observed according to the deposition process variables has the effects on the resultant film properties. Under the same preparation condition conditions of the substrate and process variables, physical morphology variations characterized by substrate temperature and bias which offect the surface mobility of adatom and adhesion variations related to the formation of Ti interlayer were considered in the present study. Microhardness showed the highest value around 40$0^{\circ}C$ of the substrate temperature and increased with the substrate bias. Adhesion was improved with the increase of substrate temperature and bias. An interlayer of pure titanium formed prior to deposition of TiN improves the adhesion at its optimum thickness. These results were explained by the change of physical morphology and phase analysis.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3764-3771
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• 2021

Based on the convolutional neural network (CNN), a novel technique is investigated for lost gamma source detection in a room. The CNN is trained with the result of a GEANT4 simulation containing a gamma source inside a meshed room. The dataset for the training process is the deposited energy in the meshes of different n-step paths. The neural network is optimized with parameters such as the number of input data and path length. Based on the proposed method, the place of the gamma source can be recognized with reasonable accuracy without human intervention. The results show that only by 5 measurements of the energy deposited in a 5-step path, (5 sequential points 50 cm apart within 1600 meshes), the gamma source location can be estimated with 94% accuracy. Also, the method is tested for the room geometry containing the interior walls. The results show 90% accuracy with the energy deposition measurement in the meshes of a 5-step path.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.597-609
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• 2020

Accident Tolerant Fuels have been widely studied since the Fukushima-Daiichi accident in 2011 as one of the options on how to further enhance the safety of nuclear power plants. Deposition of protective coatings on nuclear fuel claddings has been considered as a near-term concept that will reduce the high-temperature oxidation rate and enhance accidental tolerance of the cladding while providing additional benefits during normal operation and transients. This study focuses on experimental testing of Zr-based alloys coated with Cr-based coatings using Physical Vapour Deposition. The results of long-term corrosion tests, as well as tests simulating postulated accidents, are presented. Zr-1%Nb alloy used as nuclear fuel cladding serves as a substrate and Cr, CrN, Cr_xN_y layers are deposited by unbalanced magnetron sputtering and reactive magnetron sputtering. The deposition procedures are optimized in order to improve coating properties. Coated as well as reference uncoated samples were experimentally tested. The presented results include standard long-term corrosion tests at 360℃ in WWER water chemistry, burst (creep) tests and mainly single and double-sided high-temperature steam oxidation tests between 1000 and 1400℃ related to postulated Loss-of-coolant accident and Design extension conditions. Coated and reference samples were characterized pre- and post-testing using mechanical testing (microhardness, ring compression test), Thermal Evolved Gas Analysis analysis (hydrogen, oxygen concentration), optical microscopy, scanning electron microscopy (EDS, WDS, EBSD) and X-ray diffraction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.276-279
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• 2004

Plasma enhanced chemical vapor deposition (PECVD) of silicon nitride (SiN) is a proven technique for obtaining layers that meet the needs of surface passivation and anti-reflection coating. In addition, the deposition process appears to provoke bulk passivation as well due to diffusion of atomic hydrogen. This bulk passivation is an important advantage of PECVD deposition when compared to the conventional CVD techniques. A further advantage of PECVD is that the process takes place at a relatively low temperature of 300t, keeping the total thermal budget of the cell processing to a minimum. In this work SiN deposition was performed using a horizontal PECVD reactor system consisting of a long horizontal quartz tube that was radiantly heated. Special and long rectangular graphite plates served as both the electrodes to establish the plasma and holders of the wafers. The electrode configuration was designed to provide a uniform plasma environment for each wafer and to ensure the film uniformity. These horizontally oriented graphite electrodes were stacked parallel to one another, side by side, with alternating plates serving as power and ground electrodes for the RF power supply. The plasma was formed in the space between each pair of plates. Also this paper deals with the fabrication of multicrystalline silicon solar cells with PECVD SiN layers combined with high-throughput screen printing and RTP firing. Using this sequence we were able to obtain solar cells with an efficiency of 14% for polished multi crystalline Si wafers of size 125 m square.

• Korean Journal of Materials Research
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• v.24 no.4
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• pp.194-200
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• 2014

Metallic Cr film coatings of $1.2{\mu}m$ thickness were prepared by DC magnetron sputter deposition method on c-plane sapphire substrates. The thin Cr films were ammoniated during horizontal furnace thermal annealing for 10-240 min in $NH_3$ gas flow conditions between 400 and $900^{\circ}C$. After annealing, changes in the crystal phase and chemical constituents of the films were characterized using X-ray diffraction (XRD) and energy dispersive X-ray photoelectron spectroscopy (XPS) surface analysis. Nitridation of the metallic Cr films begins at $500^{\circ}C$ and with further increases in annealing temperature not only chromium nitrides ($Cr_2N$ and CrN) but also chromium oxide ($Cr_2O_3$) was detected. The oxygen in the films originated from contamination during the film formation. With further increase of temperature above $800^{\circ}C$, the nitrogen species were sufficiently supplied to the film's surface and transformed to the single-phase of CrN. However, the CrN phase was only available in a very small process window owing to the oxygen contamination during the sputter deposition. From the XPS analysis, the atomic concentration of oxygen in the as-deposited film was about 40 at% and decreased to the value of 15 at% with increase in annealing temperature up to $900^{\circ}C$, while the nitrogen concentration was increased to 42 at%.