• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.539-550
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• 2021

In this study, Zn and Zn-15Al were coated on general carbon steel by plasma arc metal spraying and then immersed in a 3.5wt.% NaCl solution similar to the seawater environment to evaluate the corrosion resistance properties. Through the surface shape analysis test by SEM and XRD, it was found that the Zn coating was porous and needle-shaped, so the penetration of the electrolyte was easy, and thus the corrosion rate was rapid. On the other hand, the Zn-15Al coating had a uniform and dense shape and was shown to suppress corrosion.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.108-111
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• 2014

Low arc weldability of aluminum alloy is enhanced by applying variable polarity TIG and the result is theoretically investigated to figure out the mechanism. Conventionally, it is well known fact that DCEP (reverse polarity) arc is effective on aluminum welding. The reason is due to oxide layer removal by plasma ion bombardment and therefore it is named as cleaning effect. Another fact of polarity characteristic is that DCEN shows higher heat input efficiency therefore conventional variable polarity arc used to apply DCEP portion as small as possible. However, higher DCEP portion shows bigger weldment in this research and it is explained by adopting a theory of arc concentration on oxide layer with tunneling effect which was not clearly mentioned before in several variable polarity TIG welding research. Disagreement between variable polarity TIG welding result and conventional arc polarity theory is rationally explained for the first time with help of electron emission theory.

• Journal of Powder Materials
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• v.15 no.5
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• pp.352-358
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• 2008

The present study focused on the synthesis of a bismuth-antimony-tellurium-based thermoelectric nanopowders using plasma arc discharge process. The chemical composition, phase structure, particle size of the synthesized powders under various synthesis conditions were analyzed using XRF, XRD and SEM. The powders as synthesized were sintered by the plasma activated sintering. The thermoelectric properties of sintered body were analyzed by measuring Seebeck coefficient, specific electric resistivity and thermal conductivity. The chemical composition of the synthesized Bi-Sb-Te-based powders approached that of the raw material with an increasing DC current of the are plasma. The synthesized Bi-Sb-Te-based powder consist of a mixed phase structure of the $Bi_{0.5}Sb_{1.5}Te_{3}$, $Bi_{2}Te_{3}$ and $Sb_{2}Te_{3}$ phases. This powder has homogeneous mixing state of two different particles in an average particle size; about 100nm and about 500nm. The figure of merit of the sintered body of the synthesized 18.75 wt.%Bi-24.68 wt.%Sb-56.57 wt.%Te nanopowder showed higher value than one of the sintered body of the mechanically milled 12.64 wt.%Bi-29.47 wt.%Sb-57.89 wt.%Te powder.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.707-714
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• 2003

Plasma Arc Curing(PAC) units operate at relatively high intensity and claimed to result in optimum properties of composite resin in a short curing time, so the interest of pediatric dentists about PAC units have been increased recently. But PAC units used for polymerizing restorative resins produce heat during operation. The purpose of this study was to evaluate temperature transmission through dentin of various depths using two types of PAC units(Flipo, Q-Lux plasma 100). The results from the present study can be summarized as follows : 1. When PAC be used continuously, temperature on tip was increased as curing times, and Q-Lux showed greater temperature rising(p<0.001). 2. Compared temperature transmission as dentin depth, temperature rising rate was decreased as dentin thickened(0.5, 1.0, 1.5, 2.0mm)(p<0.05). 3. Compared temperature transmission as resin depth, temperature rising rate was also decreased as resin thickened(1.0, 2.0mm)(p<0.05).

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.457-457
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• 2012

We presented plasma processing using a DC Arc Plasmatron for diamond deposition on Al2O3 ceramic substrates. Plasma surface treatments were conducted to improve deposition condition before processing for diamond deposition. The Al2O3 ceramic substrates deposited, $5{\times}15mm^2$, were investigated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). Properties of diamond (111), (220) and (311) peaks were shown in XRD. We identified nanocrystalline diamond films on substrates. The results showed that deposition rate was approximately $2.2{\mu}m/h$ after plasma surface treatments. Comparing the above result with a common processing, deposition rate was improved. Also, the surface condition was improved more than a common processing for diamond deposition on Al2O3 ceramic substrates.

• Journal of Welding and Joining
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• v.9 no.4
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• pp.69-74
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• 1991

The Plasma Arc Cutting Method using high density and hight temperature beam is well applicable to the cutting of the nonferrous metal (Al alloy ) and stainless steel which are unable to be cut by the use of the oxy-fuel gas. This study focalizes on the cutting phenomena of the plate of (mm) thickness, since the cutting phenomena of thick plates have been rather thoroughly studied. In this study the cutting groove, adhesive phenomena of dross, surface roughness were measured according to the variation of cutting speed and compared with the case of mild steel plates. The result showed that the kerf width variation of Al alloy was similar to the case of mild steel, while that of the stainless steel differed from the mild steel. In the adhesive phenomena of dross, 6(mm) thick plates of Al alloy showed a difference from those of thick plates, but the stainless steel was similar to thick plates. The surface roughness variation of Al alloy wias minimum at 67 cm/min, while that of stainless steel was at 30cm/min.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.269-269
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• 2012

A new ion source has been designed, fabricated, and installed at the NBTS (Neutral Beam Test Stand) at the KAERI (Korea Atomic Energy Research Institute) site. The goalis to provide a 100 keV, 2MW deuterium neutral beam injection as an auxiliary heating of KSTAR (Korea Super Tokamak Advanced Research). To cope with power demand, an ion current of 50 A is required considering the beam power loss and neutralization efficiency. The new ion source consists of a magnetic cusp bucket plasma generator and a set of tetrode accelerators with circular copper apertures. The plasma generator for the new ion source has the same design concept as the modified JAEA multi-cusp plasma generator for the KSTAR prototype ion source. The dimensions of the plasma generator are a cross section of $59{\times}25cm^2$ with a 32.5 cm depth. The anode has azimuthal arrays of Nd-Fe permanent magnets (3.4 kG at surface) in the bucket and an electron dump, which makes 9 cusp lines including the electron dump. The discharge properties were investigated preliminarily to enhance the efficiency of the beam extraction. The discharge of the new ion source was mainly controlled by a constant power mode of operation. The discharge of the plasma generator was initiated by the support of primary electrons emitted from the cathode, consisting of 12 tungsten filaments with a hair-pin type (diameter = 2.0 mm). The arc discharge of the new ion source was achieved easily up to an arc power of 80 kW (80 V/1000 A) with hydrogen gas. The 80 kW capacity seems sufficient for the arc power supply to attain the goal of arc efficiency (beam extracted current/discharge input power = 0.8 A/kW). The accelerator of the new ion source consists of four grids: plasma grid (G1), gradient grid (G2), suppressor grid (G3), and ground grid (G4). Each grid has 280 EA circular apertures. The performance tests of the new ion source accelerator were also finished including accelerator conditioning. A hydrogen ion beam was successfully extracted up to 100 keV /60 A. The optimum perveance is defined where the beam divergence is at a minimum was also investigated experimentally. The optimum hydrogen beam perveance is over $2.3{\mu}P$ at 60 keV, and the beam divergence angle is below $1.0^{\circ}$. Thus, the new ion source is expected to be capable of extracting more than a 5 MW deuterium ion beam power at 100 keV. This ion source can deliver ~2 MW of neutral beam power to KSTAR tokamak plasma for the 2012 campaign.

• Special Issue of the Society of Naval Architects of Korea
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• 2006.09a
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• pp.122-127
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• 2006

In case of lap joint fillet welds of thin plate, the example which is applicable to Plasma Welding increases substituting for the exiting TIG Welding but the quality of Plasma arc welding has a special feature influenced sensitively by the condition of welding caused by controlling the various parts of welding torch. This research is purposed to improve lap joint fillet welds of thin plate in high quality and attain the high productivity and it is examined that how the change of electrode tip angle and Setback has an effect on the quality of welding and it is investigated how the change of Setback and Standoff has an effect on Melting efficiency using Response Surface Analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.669-673
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• 2011

This study explores the numerical analysis method of fluid dynamics in the reaction section to improve the gas processing efficiency in the hazardous gas removal by atmospheric thermal plasma. This study also intends to contribute in technology advance to improve the processing efficiency and make the process more stable. Numerical analysis of temperature distribution in the reaction section dependent on the change in flow velocity of Ar and plasma temperature change, which are major control variables in the cracking process of HFC-23 using arc plasma, was done. The characteristic of incoming oxygen by temperature suggested that when temperature increased to 1600K, 1700K, 1800K respectively, the range of cracking temperature 1500K increased to 75.0%, 83.3%, 90.2% respectively. The temperature change of Ar by velocity change was widest in the area higher than 1500K when the velocity was 2.5m/s; however, since there was no big difference when the velocity was 2m/s, it is believed that 2 m/s would be most proper.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.220-223
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• 1988

A the dependent model for wail-stabilized local thermodynamic equilibrium (LTE) arcs has been used to examine the high-pressure sodium vapor arc. Arc properties including temperature, electrical conductivity, and optically thick and optically thin radiation fluxes were calculated as functions of radius and time.