• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.101-112
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• 2016

The characteristic analysis and fundamental test of a plasma generator is performed for drag reduction of a high speed vehicle. In high pressures, thermal plasmas is suitable for generating plasmas. The appropriate plasma torch is selected and used to generate thermal plasmas. The plasma torch, which can emit high-speed and high-pressure plasma jet, is suitable for generating plasma counterflow jet. In this study, the fundamental test and analysis for the plasma torch is summarized. Results show that supplying gas pressures and electrode gap of plasma torch are considered as critical parameters for generating plasma jets.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.73-80
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• 2016

The preliminary test for the dual mode plasma torch system was carried out to explore the operation properties in advance. The dual mode plasma torch system that is able to operate in transferred, non-transferred, or dual mode is very adequate for melting the mixed wastes including nonconductive materials such as concrete, asbestos, etc. since it exploits both the high efficiency of heat transfer to the melt in transferred mode and stable operation in non-transferred mode. Also, system operation including restarting is reliable and very easy. A stationary melter with a refractory structure was designed and manufactured considering the melting behavior of slags to minimize the refractory erosion. The power supply for the dual mode plasma torch system built with high power insulated gate bipolar transistor (IGBT) modules has functions for both current control and voltage control and is sufficient to suppress the harmonics during the operation of the plasma torch. The power supply provides two different voltages for transferred operation and non-transferred. It is confirmed that the operation voltage in transferred is always higher than non-transferred. The dual mode plasma torch system was successfully developed and is under operation for a melting experiment to optimize operation data.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.48-53
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• 2003

The high temperature melting test for nonflammable wastes using a plasma torch was conducted. The AP-200L hollow cathode type plasma torch was installed at the pilot plasma melting furnace in NETEC. The surrogates were prepared to simulate concrete, soil and their mixture with steel. The experimental conditions such as feeding rate, the distance between melts surface and torch nozzle, torch rotation speed, gas flow rate and pressure in the furnace were decided. Basic parameters such as temperatures of cooling waters, off-gas and torch power were measured. The vitrified samples were analyzed by SEM/EDS.

• Resources Recycling
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• v.14 no.1
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• pp.39-46
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• 2005

A solid-state high power torch with inter-electrode insert (IEI) was developed to treat solid waste (for example, incinerated ash), and it's operation characteristics were obtained in the plasma facility test for waste treatment. According to torch test from this study, at the non-transferred mode voltage is increased by gas volume proportionally, and at the transferred mode it is not affected to voltage change. Especially arc voltage is sustained stable at the range of 10% of total Fe in slag. In addition, Electrical conductivity is 0.05~0.25${\Omega}^{-1}cm^{-1}$, torch efficiency is 75~85% and Erosion rate is 2${\times}10^{-6}~6{\times}10^{-6}$ kg/s.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.537-540
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• 2010

An Enhanced Huels Type Plasma Torch that generates over $5000^{\circ}C$ plasma arc flow is the core equipment of arc-jet wind tunnel. It is applied to the high-tech areas such as a new materials development and eco-friendly industry. Although the Enhanced Huels Type Plasma Torch produce uniform flow of high purity, its complicated structure and operating condition makes the commercialization of it to be difficult. The 400kW arc-jet generator using the enhanced Huels type plasma torch was tested. The result of this study showed that the torch was operated in the range of 280~320 A and 250~1350 V.

• Journal of the Korean institute of surface engineering
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• v.29 no.1
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• pp.45-59
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• 1996

Ultrafine powders(UFPs) of aluminum nitride(AlN) have been synthesized by chemical reactions in the nitrogen atmosphere and the gaseous aluminum evaporated from Al powders in thermal plasmas produced by a DC plasma torch. A synthesis system consisting of a plasma torch, a finely-controllable powder feeder, a reaction chamber, and a quenching-collection chamber have been designed and manufactured, and a filter for gathering AlN UFPs produced by the quenching process subsequent to the synthesis is set up. The synthesis process is interpreted by numerical analyses of the plasma-particle interaction and the chemical equilibrium state, respectively, and a fully-saturated fractional factorial test is used to find the optimum process conditions. The degrees and ultrafineness of synthesis are evaluated by means of SEM, TEM, XRD, and ESCA analyses. AlN UFPs synthesized in the optimum process conditions have polygonal shapes of the size of 5-100 nm, and their purities differ depending on collecting positions and filter types, and the maximum purity obtained is 72 wt% at the filter.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.8-16
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• 2023

In this work, we report basic performance test results of a lab-scale three phase alternative current (AC) arc plasma torch system for plasma gas reforming applications. The suggested system primarily consists of three graphite electrodes inclined at 12.5° to the central axis, a 𝞥 150 mm cylindrical gas path and a three phase-60 Hz AC power supply. At air flow rate of 50 Lpm and arc currents of 100-175 A, test results revealed that plasma resistances were decreasing from 1.08 Ω to 0.53 Ω with the increase of plasma power from 9.3 kW to 13.8 kW, causing the decrease of power factor and increase of the line voltages. However, the injected air can be heated quickly up to the temperatures of >1,200℃ when injecting AC arc plasma powers of >10 kW.

• Clinical and Experimental Pediatrics
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• v.61 no.4
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• pp.114-120
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• 2018

Purpose: Routine screening for toxoplasmosis, rubella, cytomegalovirus (CMV), and herpes simplex virus (TORCH) in intrauterine growth restriction (IUGR) and small for gestational age (SGA) neonates has become a common practice. However, the incidence of TORCH varies across countries, and the cost of TORCH testing may be disadvantageous compared to disease-specific screening. To evaluate the efficacy of TORCH screening, the medical charts of IUGR or SGA neonates born in a single institution in Bucheon, Korea from 2011 to 2015 were reviewed. Methods: The clinical data of the 126 IUGR or SGA neonates were gathered, including gestational age, Apgar scores, neonatal sonographic findings, chromosome study, morbidities, developmental follow-up, and growth catch-up. Maternal factors including underlying maternal disease and fetal sonography were collected, and placental findings were recorded when available. TORCH screening was done using serum IgM, CMV urine culture, quantification of CMV DNA with real-time polymerase chain reaction, and rapid plasma reagin qualitative test for syphilis. Tests were repeated only for those with positive results. Results: Of the 119 TORCH screenings, only one was positive for toxoplasmosis IgM. This result was deemed false positive due to negative IgM on repeated testing and the absence of clinical symptoms. Conclusion: Considering the incidence and risk of TORCH in Korea, the financial burden of TORCH screening, and the single positive TORCH finding in our study, we suggest disease-specific screening based on maternal history and the clinical symptoms of the neonate. Regarding CMV, which may present asymptomatically, universal screening may be appropriate upon cost-benefit analysis.

• Journal of Powder Materials
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• v.18 no.3
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• pp.226-237
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• 2011

W-ZrC and W-HfC composite powders were fabricated by the Plasma Alloying & Spheroidization (PAS) method and the powders were sprayed into hybrid coating layers by using Low Vacuum Plasma Spray (LVPS) process, respectively. Microstructure, mechanical properties, and ablation characteristics of the fabricated coating layers were investigated. The LVPS process led to successful production of W-Carbide hybrid coatings, approximately 400 ${\mu}M$ or above in thickness. As the substrate preheating temperature increased from $870^{\circ}C$ to $917^{\circ}C$, the hardness of the W-ZrC coating layer increased due to decreased porosity. Vickers hardness showed higher value (about 108.4 HV) in W-ZrC hybrid coating material compared to that of W-HfC while adhesive strength was found to be similar in both coating layers. The plasma torch test revealed good ablation resistance of the W-Carbide hybrid coating layers. The relatively high performance W-ZrC coating layer at the elevated temperature is thought to be attributed to both the strengthening effect of ZrC particle remained in the layer and the formation of ZrO2 phase with high temperature stability.

• Corrosion Science and Technology
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• v.4 no.1
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• pp.23-28
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• 2005

Several plasma-sprayed ceramic coatings with two- and three-layers were characterized and tested for the application of cooling tube coatings of oxygen convert gas recovery system (OG cooling system) in the steel making plant. Thermal cycling tests using a torch heating with compressed air cooling were carried out and characterized before and after the tests. The effects of metallic bond coat as well as ceramic top coat were also studied. Possible failure mechanisms with low carbon steel substrate were assessed in term of microstructure, porosity, bond strength, thermal expansion coefficient, and the phase transformation. Finally, the results of field tests at the OG cooling system are presented and discussed their microstructural degradation. Test results have shown that three-layered coatings perform better than two-layered coatings.