• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.4
• /
• pp.158-163
• /
• 2002

The pulsed Power system has been widely used to many applications, such as E/P(Electrostatic Precipitator), DeNOx/DeSOx power system, often generator, etc. In this paper, we study EMTP analysis and characteristics of critical voltage and load in impedance on various electrode length of pulse corona. To obtain a stable pulse voltage, we designed a compact pulse generator switched MOSFET and tested their characteristics by adjusting electrode length and pulse repetition. As a re sult, critical voltage of pulse corona and load impedance on increasing electrode length were decreased. These results indicate we can control critical voltage of pulse corona and suppress arc discharging between two electrodes.

• Tribology and Lubricants
• /
• v.18 no.1
• /
• pp.16-23
• /
• 2002

For increasing the yield stress of ER fluids, the compressing ER electrode was developed and the compressing electrorheological (ER) behavior of anhydrous ER fluids in silicone oil of phosphorous ester cellulose powder was investigated. Under constant electric field, not only the current density but also the yield stress of anhydrous ER fluids were studied as varying the compressing length of ER electrode distance. From the experimental results the compressing of ER electrode had a large influence to the ER properties of anhydrous ER fluids. The current density was proportional to the compressing length of ER electrode under constant electric field and volume fraction also tile compressing yield stress was proportional to the volume fraction of dispersed particles under constant electric field and compressing length. When the ER electrode was compressed with 150mm after charging the electric field, 4 kV, tile yield stress of phosphoric ester cellulose ER fluids increased to thirteen times comparing with the yield stress measured at normal electrode.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.11a
• /
• pp.138-145
• /
• 2001

For increasing the yield stress of ER fluids, the compressing ER electrode was developed and the compressing electrorheological (ER) behavior of anhydrous ER fluids in silicone oil of phosphorous ester cellulose powder was investigated. Under constant electric field, not only the current density but also the yield stress of anhydrous ER fluids were studied as varying the compressing length of compressing ER electrode. From the experimental results, the compressing of ER electrode had a large influence to the ER properties of anhydrous ER fluids. The current density was proportional to the compressing length of ER electrode under constant electric field and volume fraction also the compressing yield stress was proportional to the volume fraction of dispersed particles under constant electric field and compressing length. When the ER electrode was compressed with 150mm after charging the electric field, 4 kV, the yield stress of phosphoric ester cellulose ER fluids increased to thirteen times comparing with the yield stress measured at normal electrode.

• Journal of Advanced Marine Engineering and Technology
• /
• v.23 no.5
• /
• pp.671-677
• /
• 1999

This study has been performed to investigate REW(relative electrode wear) in condition of vari-ous pulse-on duration using the copper and graphite electrode with change of the electrode size on the heat treated STD11 which is extensively used for metallic molding steel with the EDM. The results obtained are as follows; a) Graphite has much benefits than copper electrode when rapid machining is done without electrode wear, b) Neative REW result from the electrode that is very liable attach to decomposition carbide c)Increasing of machining time cause to increase wear length of the copper electrode and decrease wear length of the graphite electorde d)The more pulse-on duration copper electrode has the less REW. e) The edge portion of the electorde wears remarkably at the beginning of machining,.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1491_1492
• /
• 2009

The impedance of a vertical grounding electrode is not lowered by expanding the dimension of the grounding electrode, and the length of thr vertical grounding electrode which shows the minimum value of the grounding impedance for each condition of frequency and soil characteristics is existent, and it is defined as Critical length. In this paper, the critical lengths for the vertical grounding electrodes are calculated by using the distributed parameter circuit model. The adequacy of the simulations has been confirmed by comparing the simulated results with the measured results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.157-162
• /
• 2003

This Paper presents a robust design of an Electrorheological(ER) damper using Taguchi method. Taguchi method is a robust design method that determines control parameters in the presence of noise effect. Electrode length, electrode gap, base oil viscosity and the weight ratio of ER particles are chosen for the control parameters and the temperature is considered to be a noise factor. The sensitivity of each factor with signal-to-noise(S/N) ratio and analysis of variance are investigated. The analysis results show that the electrode length and base oil viscosity of the ER fluid mostly affect the damping force in the absence of electric field. On the other hand, when the voltage is applied to the ER damper, the electrode length and the weight ratio of ER fluid exhibit significant effect. Based on the Taguchi method, an optimal configuration was designed and the robustness of the designed ER damper was validated by comparing the analysis and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.53 no.5
• /
• pp.264-267
• /
• 2004

Recently the pulsed power systems have been widely used in many fields such as E/P(Electrostatic Precipitator), DeNOx/DeSOx power systems, ozone generators and power sources of the laser beam. In this paper, we studied various electrical characteristics for arc suppression of line-to-line electrodes in air and removal of the metaloxide using our pulsed power system. To obtain high efficiency of the pulsed power system, we repeatedly experimented and tested their characteristics. by adjusting electrode length of the load. As a result, when the value of the electrode length and pulse repetition rate were changed at the load, the value of the arc voltage changed at the electrode load. In conclusion, we controlled arc voltage of the load by ,changing electrode length and pulse repetition rate. Also. we stydied removal area of the metaloxide using area discharge according to pulse repetition rate.

• Journal of Welding and Joining
• /
• v.28 no.4
• /
• pp.73-80
• /
• 2010

In this work, the effect of welding variables on weldability of gas tungsten arc(GTA) welding was investigated with experimental analysis for a commercial pure(CP) titanium (Grade.1). The GTA welding tests on sheet samples with 0.5mm in thick were carried out at different process variables such as arc length, welding speed and electrode shape. In order to search an optimum arc length with full penetration, bead- on-plate welding before butt-welding were performed with different arc length conditions. From the bead- on-plate welding results, the optimum condition considering arc stability and electrode loss was obtained in the arc length of 0.8mm. Butt-welding tests based on the arc length of 0.8mm were carried out to achieve the optimum conditions of welding speed and electrode shape. Optimum conditions of welding speed and electrode shape were suggested as 10 mm/s and truncated electrode shape, respectively. It was successfully validated by the microstructural observation, tensile tests, micro-hardness tests and formability tests.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.12
• /
• pp.164-170
• /
• 2010

For the surge currents like lightning or ground fault currents containing high frequency components which cause the electromagnetic interferences for the electronic devices and communication equipment, the grounding impedances give the significantly composite characteristics which are dependent on the frequency of surge currents. In this paper, the analytical model and method for determining the optimal length of the newly developed coaxial type carbon ground electrode which has a little fluctuation in grounding impedance with frequency. The length of minimizing the fluctuation of grounding impedance by changing frequency from 100[Hz] to 1[MHz] was determined, and the validity of this proposed method was confirmed by comparing with the simulated and measured data.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.30 no.2 s.245
• /
• pp.95-100
• /
• 2006

Electrostatic precipitators(EPs) have low pressure drop and high dust collection efficiency and are widely used for industrial dust collectors. The current-voltage characteristics, which are important to maintain high dust collection efficiency, depend on several factor: discharge electrode shape, gas flow property, dust loading etc. In this study, experiments are performed to investigate the current-voltage characteristics of the corona discharge of various electrode geometries and an empirical model is proposed to predict current-voltage characteristics of the corona discharge. The corona onset voltage correction coefficient$(\alpha)$ and the geometry correction coefficient$(k_g)$ are used to the conventional equation for wire-plate type discharge electrode. The corona onset voltages are -6.3kV and almost constant when the numbers of discharge pins are varied from 3 to 9. The length of discharge pins has very sensitive effects on the corona onset voltage. They are increased from -6.3 to -7.8kV when the discharge pin length are 8.5 and 4.5mm, respectively. The empirical model shows good agreement with experimental results and can predict the effects of discharge pin length and number.