• Transactions of the Korean hydrogen and new energy society
• /
• v.7 no.2
• /
• pp.165-171
• /
• 1996

The effect of rolling on the charge-discharge property was studied for metal hydride negative electrode. $(LM)Ni_{3.6}Al_{0.4}Co_{0.7}Mn_{0.3}$(pleateau pressure : below 1 atm at room temperature, volume expansion : 9%, entalpy : $8.7kcal/molH_2$) alloy was prepared by arc melting, and then it was coated with various copper weight percent. The copper coated alloys were then rolled with the different reduction ratio. From the results, it was found that the maximum discharge capacity increased with increasing reduction ratio, and 15wt% copper coated sample shows the highest discharge capacity, 324mAh/g, after rolling with 30% reduction ratio. In view of cycle life for the negative electrode, the 15wt% copper coated electrode which was rolled with 13% reduction ratio showed the longest cycle life compared with other electrodes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.3
• /
• pp.279-285
• /
• 2008

CNC (Carbon Nano Colloid) was used as an additive to the positive electrode to improve the discharge performance of sealed lead-acid batteries, The cathode active material ($PbO_2$) has a relatively low utility of less than 60 % compared with other kind of batteries, such as Ni-MH and Lithium ion, In this study, to overcome the above-mentioned problem we investigated the effects of CNC addition on the enhancement of electrical connection with not-utilized $PbO_2$ and resultantly electrical conductivity of electrode, We examined low rate discharge capacities, high rate discharge capacities and internal resistances of the batteries containing various amounts of CNC. From these results, we found out that the addition of CNC into the positive electrode made a significant improvement in high rate discharge capacity, We also suggested the optimum content of CNC material in positive electrode.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 1999.11a
• /
• pp.17-22
• /
• 1999

In this paper a new discharge type ozonizer comprising the superpose operation of silent and surface discharge is presented. The ozonizer consists of two concentric glass tubes with three type of discharge electrodes : the external electrode(EE), the internal electrode(IE) and the central electrode(CE). By varying the structure of IE and materials of CE, we analyzed the characteristics of ozone related different parameters including $O_{3con}$, $O_{3g}$, and $O_{3Y}$. Using Cu made CE it was found the O3con is higher with Cu tape than that with Cu coil wound IE. At Q = 1[l/ min] the values of O3con were found as 3000[ppm] with Cu tape wound IE and 1898[ppm] with Cu coil wound IE. Then using SUS wire made CE with Cu tape wound IE at Q = 1[ι/ min] the maximum value of O3con was found as 5632[ppm]. It was observed that both $O_{3con}$ and $O_{3y}$ are higher with SUS made CE than that with Cu made CE. The maximum values of $O_{3Y}$ were found as 79[g/kWh] with Cu made CE and 170[g/kWh] with SUS wire made CE.

• Journal of Korean Society for Atmospheric Environment
• /
• v.31 no.6
• /
• pp.530-537
• /
• 2015

The wet electrostatic precipitator (wet ESP) is an effective control device which removes submicron particles reentrained in a collection plate and water soluble gas. However, its collection efficiency decreases, as its operation is subject to water-induced distortion of the collection electrode. In order to make up for the limitation, we modified the wet ESP system by installing electrosprayed discharge electrodes. The modified wet ESP system can wash both the collection plate and discharge electrode. As a result, we were able to fabricate a compact wet ESP with a small specific collecting area ($0.18m^2(m^3/min)$) that can accomplish a high collection efficiency of fine particles (97.1%). In addition, the device obtained a relatively low specific corona power of approximately $10W/(m^3/min)$.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.4 no.3
• /
• pp.32-38
• /
• 2005

Electrical discharge machining is the method of using thermal energy by electrical discharge. Generally, if the material of workpiece has conductivity even though very hard materials and complicated shape which are difficult to cut such as quenching steel, cemented carbide, diamond and conductive ceramics, the EDM process is favorable one of possible machining processes. But, the process is necessarily required of finish cut and heat treatment because of slow cutting speed, no mirror surface, brittleness and crack due to the residual stress for manufactured goods. In this experimental thesis, the super EDM drilling was developed for high precision semiconductor die steel and for minimization of leadframe width. It was possible to development of EDM drilling machine for high precision semiconductor die with the electrode guide and its modelling and stress analysis. The development of electrode with the copper pipe type was conducted to drill the hole from the diameter of 0.1mm to 3.0mm with the error of from 0.02mm to 0.12mm. From the SEM and EDX analysis, the entrance of the EDM drill was found the resolidification of not only the component of tungsten but also the component of copper.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.31-36
• /
• 2001

As a part of micro engine development feasibility estimation was done through fabrication and test of down scaled combustor and MEMS fabricated spark electrode. In an experimental observation of the down scaled combustion phenomena where flame propagation was observed by optical method and pressure change in combustor which gives the information about the reaction generated thermal energy was recorded and analyzed. Optimal combustor scale was derived to be about 2mm considering increased heat loss effect and thermal energy generation capability. Through the fabrication and discharge test of MEMS electrode effects of electrode width and gap was investigated. Electrode was fabricated by thick PR mold and electroplating. From the result discharge voltage characteristic in sub millimeter scale electrode having thickness of $40{\mu}m$ was obtained. From the result base technology for design and fabrication of micro engine was obtained.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1999.05a
• /
• pp.245-250
• /
• 1999

The experimental study of die-sinking electrical discharge machining for alloy tool steel of STD-11 with circular electrode was conducted for various conditions of the peak current and duty factor with the change of internal size of electrode for distributing the amount of dielectric flow through the electrode. From this study, the material removal rate(MRR) was found to be increased with the peak current and duty factor. The more MRR was obtained for the case of electrode inside diameter of 10mm. The surface roughness and roundness values were analyzed regularity under various conditions, and these values were not affected by the inside diameter change of electrode.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.315-316
• /
• 2002

Electrochemical discharge machining is a very recent technique for non-conducting materials such as ceramics and glasses. ECDM is conducted in the NaOH solution and the cathode electrode is separated from the solution by $H_2$ gas bubble. Then the discharge is appeared and the non-conductive material is removed by spark and some chemical reactions. In the ECDM technology, the $H_2$ bubble control is the most important factor to stabilize the discharging condition. In this paper, we proposed the discharge peak monitoring/ discharging duty feedback algorithms for the discharge stabilization and the feasibility of this algorithm is verified by various pattern machining in the constant preload conditions for the cathode electrode.

• KSTLE International Journal
• /
• v.3 no.2
• /
• pp.95-100
• /
• 2002

Electrochemical discharge machining is a very recent technique for non-conducting materials such as ceramics and glasses. ECDM is conducted in the NaOH solution and the cathode electrode is separated from the solution by H$_2$ gas bubble. Then the discharge is appeared and the non-conductive material is removed by spark and some chemical reactions. In the ECDM technology, the H$_2$ bubble control is the most important factor to stabilize the discharging condition. In this paper we proposed the discharge peak monitoring/discharging duty feedback algorithms fur the discharge stabilization and the feasibility of this algorithm is verified by various pattern machining in the constant preload conditions for the cathode electrode.

• Journal of Korean Society for Atmospheric Environment
• /
• v.18 no.5
• /
• pp.337-344
• /
• 2002

In this study, we analyzed the NO removal efficiency by the pulsed corona discharge process and investigated the effects of several process variables such as initial concentrations of NO, $H_2O$, and NH$_3$, applied voltage, pulse frequency, diameter of the discharge electrode, and residence time. The removal efficiency of NO increased by the addition of $H_2O$ or NH$_3$, but the changes of initial NH$_3$ and $H_2O$ concentrations did not affect the removal efficiency of NO significantly. With the increases of the applied voltage or the residence time, the removal efficiency of NO increased. In addition, with the increases of the pulse frequency of applied voltage, or the diameter of the discharge electrode, the removal efficiency of NO increased. The experimental results can be used as a basis to design the pulsed corona discharge process to remove NO$_{x}$, SO$_{x}$ and VOCs.OCs.