• Journal of Korea Foundry Society
• /
• v.27 no.4
• /
• pp.179-183
• /
• 2007

The TiC layer was formed on Ti and Ti alloys by plasma carburizing method. The main experimental parameters for plasma car boozing were temperature and time. XRD, EDX, hardness test and corrosion test were employed to analyze the evolution and material properties of the layer. The preferred orientation of TiC layers is (220) at treated temperature of $700^{\circ}C\;and\;880^{\circ}C$ However, it is changed to (200) at temperature of $800^{\circ}C$ The thickness of carbide layer increase with increasing carburizing temperature. Highest hardness of hardened layer formed on CP-Ti was obtained at the carburizing condition of processing temperature $880^{\circ}C$ and processing time 1080min. The corrosion potential of carburizing specimen was higher than untreated CP-titanium, and corrosion potential increased as carburizing temperature and time increased. Thus the corrosion resistance of CP-Ti was greatly enhanced after plasma carburizing treatment.

• Applied Chemistry for Engineering
• /
• v.31 no.6
• /
• pp.624-629
• /
• 2020

For more effective temperature control of atmospheric plasma sprayed (APS) zirconia thermal barrier coating, understanding of the parameters, which influence the substrate temperature, is essential and also more numerical results based on the experimental data are required. This study aims to investigate the substrate temperature control during an APS process. The APS process deals with air-cooled systems, plasma-gas flow, powder feed rate, robot velocity, and substrate effect on the substrate surface temperature control during the process. This systematic approach will help to handle the temperature control, and thus lead to better coating quality.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.3
• /
• pp.577-582
• /
• 2007

The plasma display panel is an image expression display using gas discharge plasma. However, gas discharge characteristics vary with temperature as gas discharge is sensitive to temperature. The discharge time lag extends a lot in low temperature and it is known as the cause which hinders high speed addressing which is essential for the size enlargement of the panel. Accordingly this research aims at identifying the temperature-dependent discharge characteristic. The lower temperature becomes, the longer addressing discharge time lag becomes. Particularly the statistical time lag extends much in low temperature. The increasing of electric field shortens discharge time lag in low temperature. Also, when priming particles are sufficiently supplied, stable discharge can be performed regardless of the influence of temperature.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.10
• /
• pp.1706-1711
• /
• 2016

Electromagnetic wave simulation was performed to predict characteristics of manufactured cutoff probe at low temperature magnetized plasma medium. Microwave cutoff probe is designed for research the properties of magnetized inductively coupled plasma. It was shown that the cutoff probe method can safely be used for weakly magnetized high density plasma sources. Cutoff probe system with two port network analyzer has been prepared and applied to measure electron density distributions in large area, 13.56MHz driven weakly magnetized inductively coupled plasma source. The results shown that, the plasma frequency confirmed cut-off characteristics in low temperature plasma. Especially, cut-off characteristics was found at upper hybrid resonance frequency in the environment of the magnetic field. In case of a induced weak magnetic field in inductively coupled plasma, plasma density estimated from the cutoff frequency in the same way at unmagnetized plasma due to nearly same plasma frequency and upper hybrid resonance frequency. The plasma density is increased and uniformity is improved by applying a induced weak magnetic field in inductively coupled plasma.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.748-751
• /
• 2003

The electron temperature and plasma density in coplanar alternating-current plasma display panels (AC-PDPs) have been experimentally investigated by a micro Langmuir probe and the high speed discharge images in this experiment.

• Fisheries and Aquatic Sciences
• /
• v.26 no.2
• /
• pp.117-132
• /
• 2023

Chum salmon (Oncorhynchus keta) is a species of anadromous salmonid inhabiting coastal rivers in the North Pacific and the Arctic in the Bering and is the most widely distributed among Pacific salmon species. It is an important fish species in Korea as the salmon releasing project is being actively carried out. This study was conducted to investigate changes in the physiological activity of O. keta according to water temperature. Three experiments were conducted according to the water temperature and period, and the plasma concentrations of cortisol and glucose were analyzed from the blood samples of the experimental groups. Experiment I is a short-term water temperature experiment, in which water temperature stimulation was given for 4 hours at water temperatures of 12℃, 16℃ (control), 20℃, and 24℃, and a recovery period was given for 4 hours. Experiment II is an experiment in which water temperature stimulation was given for 24 hours, 48 hours, and 72 hours at a high temperature of 24℃, and a recovery period was given for 12 hours, respectively. Experiment III is a long-term water temperature experiment, in which the water temperature was 12℃, 16℃ (control), 20℃, and 24℃ for 8 weeks. As a result of the experiment, in Experiment I, there was no significant difference in the survival rate between the experimental groups, but the concentration of cortisol and glucose in the plasma according to the set water temperature showed a significant difference. In Experiment II, there was no significant trend according to the maintenance time of the high-temperature state, but as the temperature increased, the plasma cortisol and glucose levels significantly increased compared to the control group. In Experiment III, all of the experimental group C (24℃) died in the 1st week, and there was no significant difference in the plasma glucose at the 1st and 8th weeks among the remaining experimental groups.

• Journal of the Korean Ceramic Society
• /
• v.30 no.12
• /
• pp.1059-1065
• /
• 1993

The sliding wear behavior of the plasma sprayed zirconia containing 8wt% yttria was investigated over a range of room temperature to 800℃. Both of the friction coefficient and the wear loss increased reaching its maximum at about to 499℃. and then decreased again with increasing temperature up to 800℃. The worn surface at elevated temperature were observed and analyzed by scanning electron microscopy and X-ray diffractometer to study the mechanisms of high temperature wear behavior. Surface morphology of the worn samples changes with temperature. Monoclinic (m)/tetragonal (t) x-ray peak intensity ratio of wear debris and worn surface decreased with increasing temperature. Non-transformable tetragonal (t') to metastable tetragonal (t) phase transformation of worn surface increased with increasing temperature. The results indicate that dehumidification and above phase changes are contributing to the high temperature wear behavior of the plasma sprayed ZrO2-Y2O3 coatings.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.95-95
• /
• 2010

An apparatus for generating flames and more particularly the microwave plasma burner for generating high-temperature large-volume plasma flame was presented. The plasma burner was composed of micvrowave transmission lines, a field applicator, discharge tube, coal and gas supply systems, and a reactor. The plasma burner is operated by injecting coal powders into a 2.45 GHz microwave plasma torch and by mixing the resultant gaseous hydrogen and carbon compounds with plasma-forming gas. We in this work used air, oxygen, steam, and their mixtures as a discharge gas or oxidant gas. The microwave plasma torch can instantaneously vaporize and decompose the hydrogen and carbon containing fuels. It was observed that the flame volume of the burner was more than 50 times that of the torch plasma. The preliminary experiments were carried out by measuring the temperature profiles of flames along the radial and axial directions. We also investigated the characteristics for coal combustion and gasification by analyzing the byproducts from the exit of reactor. As expected, various byproducts such as hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, etc. were detected. It is expected that such burner cab be applied to coal gasification, hydrocarbon reforming, industrial boiler of power plants, etc.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.737-744
• /
• 2011

The success of continuous aluminum powder combustion with steam plasma is different from hydrocarbon ignition source. Ignition characteristics of aluminum powder with high temperature thermal plasma is studied with oxidizer-free environment. Experiment with argon plasma has same temperature conditions at 4500 K and particle feeding condition for previous combustion test with steam plasma and swirl combustor. The temperature of the plasma was measured using Optical Emission Spectroscopy method. Ignition characteristics were analyzed by SEM image and EDS. Aluminum powder with plasma has rapid evaporation mechanism contrast to hydrocarbon ignition source. It enhances to aluminum powder effective ignition characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.1
• /
• pp.39-44
• /
• 2014

Silicon nitride thin film deposited with Plasma Enhanced Chemical Vapor Deposition was treated by a nitrogen plasma generated by Inductively Coupled Plasma at room temperature. The treatment was investigated by Fourier Transform Infrared Spectroscopy and Atomic Force Microscopy on the surface at various RF source powers at two RF bias powers. The amount of hydrogen was reduced and the surface roughness of the films was decreased remarkably after the plasma treatment. In order to understand the causes, we analyzed the plasma diagnostics by Optical Emission Spectroscopy and Double Langmuir Probe. Based on these analysis results, we show that the nitrogen plasma treatment was effective in the improving of the properties silicon nitride thin film for flexible display.