• Journal of Powder Materials
• /
• v.11 no.4
• /
• pp.328-332
• /
• 2004

Fe nanopowders were successfully synthesized by plasma arc discharge (PAD) process using Fe rod. The influence of chamber pressure on the microstructure was investigated by means of X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The prepared particles had nearly spherical shapes and consisted of metallic cores (a-Fe) and oxide shells (Fe$_{3}$O$_{4}$), The powder size increased with increasing chamber pressure due to the higher dissolution and ejection rate of H$_2$ and gas density in the molten metal.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.544-546
• /
• 2008

An improved dual-path energy recovery circuit (ERC) using a current source and a voltage source for plasma display panel (PDP) is proposed. The proposed ERC uses the voltage source to charge a panel and the current source to discharge the panel. Thus, the proposed circuit can make the panel charge to $V_S$ and discharge to 0V, fully and it is possible to achieve zero voltage switching (ZVS) of all switches in H-bridge inverter and zero current switching (ZCS) of all switches in the ERC. Moreover, it has less conduction and switching loss in ERC devices by the dual energy recovery paths for charging and discharging the panel. Furthermore, it has features of canceling the gas discharge current, high performance and the low cost ERC components. The operation principle and features of the proposed ERC are presented in detail and verified with 42-inch SD PDP.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.4
• /
• pp.381-385
• /
• 2005

The plasma temperature of Ar gas in hollow cathode discharge were measured. This is done by measuring the line profile of the 1s/sub 8/-2p/sub 8/ transition in Ar, using a single-frequency diode laser. Low power diode lasers have been successfully used for investigation of the line profiles of Ar transitions in hollow cathode discharges. It turns out that the plasma temperature of Ar is 640∼783 K in the discharge current range at 7∼10 mA.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.1
• /
• pp.43-47
• /
• 2001

Plasma polymerized hexamethyldisiloxane thin film was fabricated by employing an inter-electrode capacitively coupled type apparatus under the following conditions : carrier gas flow rate of 11 sccm, reaction pressure of 0.1 torr, discharge frequency of 13.56 MHz and discharge power of 30∼90 W. Polymerization rate of thin film fabricated at the discharge power of 90W is 32.5nm/min. Relative dielectric constant and dielectric loss tangent of thin film shows 3.2∼3.8 and 2.6x10$\^$-3/∼4.51x10$\^$-3/ respectively in the frequency range of 1 kHz∼1 MHz. As the annealing temperature is increased, the relative dielectric constant gradually decreases while the dielectric loss tangent increases. The current density increase gradually with increasing annealing temperature and electric field. The electric conduction of the heaxamethyldisiloxane thin film shows Schottky effect.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.12
• /
• pp.1039-1044
• /
• 2000

Breakdown voltage model and expertiments are compared for discharge cells of AC plasma display panel. In the model, discharge paths are assumed to be initial electric field lines and the one-dimensional continuity equation is applied to the charged particle transport at each field line. The comparisons are performed in the wide range of gas pressure (50-600torr), Xe partial pressure over total pressure (1-6%), sustain electrode gap(100-1000$\mu\textrm{m}$), wall height(130, 300$\mu\textrm{m}$), and voltage pulse width(2-6${\mu}$s). The presented breakdown voltage model well agree with experiments in the above wide range. The increase of breakdown voltage with the decrease of the width(L) of protruding electrode is also described by the model.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.12
• /
• pp.3565-3569
• /
• 2013

A home-made pinhole-type glass nozzle was employed to generate vibronically excited but jet-cooled benzyl-type radicals from precursor 2-fluoro-4-chlorotoluene with a large amount of carrier gas He, from which the visible vibronic emission spectrum was recorded with a long-path monochromator. From an analysis of the spectrum observed, it was found that two benzyl-type radicals, 2-fluorobenzyl and 2-fluoro-4-chlorobenzyl radicals, were formed from the precursor in corona discharge. The possible pathway for the production of benzyl-type radicals that can explain the spectroscopic observation is herein proposed. In addition, the electronic energy of the $D_1{\rightarrow}D_0$ transition and the vibrational mode frequencies in the $D_0$ state of the 2-fluoro-4-chlorobenzyl radical were determined for the first time.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 1999.02a
• /
• pp.26-29
• /
• 1999

Superconducting $YBa_{2}$$Cu_{3}$ $O_{7-x}$(YBCO) thin films were deposited on MgO(100) substrates using a hollow cathode discharge sputtering system. Influence of the sputtering conditions such as substrate temperature and discharge sputtering gas pressure on electrical and structural properties were investigated. It was found that YBCO thin films with zero resistance temperature higher than 85 K were obtained to the pressure 200 mToorr(Ar/O2=0.9), substrate temperature of $760^{\circ}C$, and target-substrate distance of 10 mm during film deposition. Homogeneous large area YBCO films with 2 inch diameter were also sucessfully fabricated by this method.

• The Korean Journal of Ceramics
• /
• v.1 no.2
• /
• pp.101-105
• /
• 1995

Electrical discharge machinable $Si_3N_4$ was fabricated with the addtion of 20-60 vol% TiN by gas pressure sintering. Their sinterability, microstructure, mechanical and electrical properties were characterized as a function of the TiN content. The addition of TiN up to 20 vol% increased the flexural strength and fracture toughness as compared with those of the monolithic Si3N4. For the TiN content higher than 40 vol%, the electrical resistivity was lower than $1062\Omega$.cm. The $Si_3N_4$ with the addition of 40 vol% of TiN appears to have the optimum considerable sinterability, mechanical and electrical properties, and machinability. A microstructural analysis showed that the enhanced toughening was due to the crack deflection.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.760-763
• /
• 2003

We have investigated the electro-optical characteristics of image sticking in AC PDP. Although Image sticking is one of major factors to determine display quality in AC PDP, so far, it has not being reported why it is occurred and how we can prevent it. In this experiment, we have analyzed the effect of MgO protective layer and phosphor on the image sticking and we have measured the difference of firing voltage, brightness and discharge current between sticking image and normal image in AC PDP. As a result, Phosphor degradation is a more major factor than MgO protective layer and the firing voltage of gas discharge in sticking image is higher than that of normal discharge.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.98.3-98
• /
• 2001

The research for detecting of insulating deterioration in transformer has been studied from long ago. Analysis method of combustible gas, which is included in insulating oil, has been widely used in detection of transformer pre-fault detection due to the effectiveness of its method. Recently the fault effect of the large transformer is very critical in a power system, therefore the on-line monitoring and diagnostic system is needed. In addition, the more accurate method of detecting a Partial Discharge (PD) location should be developed. For preventive maintenance against discharge failures, it is important not only to detect the discharges, but also to accurately estimate their positions. However ...