Jin-Gyu Kim

An EHD Gas Pump Utilizing a Wet Porous Point Electrode

A point-to-mesh type electrohydrodynamic (EHD) gas pump, utilizing a wet porous point electrode, has been proposed, and the effect of the wet porous point electrode on the gas flow velocity and flow generation yield of the EHD gas pump was investigated. The wet porous point is used as a corona discharge electrode, and the mesh is used as an ion collecting electrode. It was observed that the EHD gas pump with the wet porous point electrode can generate a higher gas flow velocity and flow generation yield than the same design EHD gas pump with a non-porous metal point electrode. As a result with the wet porous electrode, a peak gas flow velocity of VW = 2.54, 2.74, and 1.93 m/s has been obtained for positive, negative, and ac corona discharges. This is 1.95, 1.31, and 1.30 times higher than the velocity VW = 1.30, 2.09, and 1.49 m/s measured with the same design EHD gas pump and a non-porous metal point electrode. At 0.1 W of input corona power for dc and ac powers, the flow generation yields of Y = 13.88, 12.80, and 11.70 m/s/W were obtained with the wet porous point electrode for the positive, negative, and ac corona discharges, which are 1.23, 1.24, and 1.15 times higher as compared with those of the metal point electrode with Y = 11.32, 10.29, and 10.20 m/s/W, respectively. These enhancements may be due to the elevated input corona powers and the water particles generated from the wet porous point electrode.

A sliding discharge-type EHD gas pump utilizing a saw-toothed-plate discharge electrode

A sliding discharge-type electrohydrodynamic (EHD) gas pump, utilizing a discrete saw-toothed-plate electrode as a discharge electrode instead of a smooth conventional-plate electrode, has been developed. The effect of the saw-toothed-plate electrode on the gas flow velocity and yield of flow generation of the EHD gas pump were investigated. It was observed that the EHD gas pump can generate a higher gas flow velocity and yield of flow generation than the same design EHD gas pump with the conventionalplate electrode. As a result, a peak gas flow velocity of VG=1.65 m/s from the EHD gas pump with the saw-toothed-plate electrode can be obtained for VP=12.0 kV, which is 2.39 times higher than that of VG =0.69 m/s of the same design EHD gas pump with the conventional-plate electrode. With the saw-toothed-plate electrode, the yield of flow generation of YG=0.435 m/Ws can be obtained for V=8.0 kV, which is 4.53 times higher than that of the same design EHD gas pump with the conventional-plate electrode of YG=0.096 m/Ws. These enhancements are due to the effect of the saw-toothed-plate electrode being utilized instead of the conventional-plate electrode.

Development of wireless wind chill temperature measurement system

The paper presents the wireless wind chill temperature measurement system that is composed of IEEE 802.15.4 standard wireless communication devices, hot film anemometer and serial communication temperature sensor. It`s sometimes very difficult for a person, who lives in a high-rise apartment, to see the outside wind chill temperature due to harsh outside weather. The wind chill temperature is calibrated from an air velocity and air temperature. IEEE 802.15.4 standard wireless communication is ZigBee compatible, and consumes low power in communication. Under the air temperature of 5 and air velocity ranging from 0 to 50 km/h, the experimental result of wind chill temperature shows good accuracy within 5%.

A Study on the Electrostatic Precipitation Using Electric Charged Carbon Filter

Air purifiers generally have used air filter, but the long time operation of the air purifier causes deterioration of the dust collecting efficiency of the air filter. Application of electrostatic force can be one of the effective method for this case. In this study, two conductive carbon filters have a function as dust collecting electrode. The two carbon filters charged with HVDC are installed across the air duct in fairs. And the dust collection and power consumption characteristics of the proposed electric precipitator are investigated experimentally. As the applied voltage was increased, the dust collection efficiency was improved. The dust collection efficiency of about 98.9% was obtained at the case 28kV applied, in this experiment. It is possible to improve the dust collection efficiency by simply applying DC voltage without power consumption.

The Study of Wind Blower Characteristics Using a Blade Type Corona Motor

In this paper, a corona motor with blade type electrodes has been employed as a wind blower. The rotation speed was influenced significantly by the polarity of applied voltage and the number of blades. Therefore the effect of polarity of applied voltage and the number of blades on the electrical and mechanical fundamental properties of corona motor were investigated experimentally. The rotation speed decreased for increasing of number of blades, because the mass of blades increased. But the amount of air blow increased despite decreasing of the rotation speed, because air volume is not only influenced by rotation speed but also the number of blades and ionic wind which generated between blade tips and a induction electrode. Although space occupied by blades of the corona motor is smaller than the whole area of the blast pipe, wind rises a whole range of a wind blower for such reasons.

Characteristics of Ozone Generation by Diameter and Polarity Variation of Corona Wire Electrode

In this paper, it was investigated experimentally that diameter and polarity variation of corona wire electrode affected to ozone generation of the ozone generator using a wire-to-plate type electrode. The change in the diameter(D) of the corona wire electrode has a great effect upon ozone generation, higher influence appears in the positive corona discharge than the negative corona discharge. In the case of D

Electrohydrodynamic Characteristics of AC Corona Discharge for the Frequency

In this paper, EHD(electrohydrodynamics) characteristics of AC corona discharge for the various frequency was investigated. Ionic wind velocity is controlled by the frequency of applied ac high voltage, and maximum velocity of the ionic wind is obtained at 1.2kHz. Maximum velocity are 1.90 m/s by metal corona electrode and 2.72m/s by wet porous corona electrode, These attain 91~99% of the maximum velocity in the DC corona discharge by adjusting the frequency through the experiments. In this paper, wet porous corona electrode has high possibility of cooling methode because a AC corona discharge using wet porous corona electrode is able to eject more water droplets than DC corona discharge.

A Study of Power Source for Wireless Sensor Node Using Supercapacitors

This paper presents the power source of wireless sensor node (WSN) using supercapacitors and a solar cell. Supercapacitors have high lifetime cycling compared to that of batteries. Supercapacitors are connected in series to achieve higher voltage and a voltage balancing circuit is required to ensure that no individual cell goes overvoltage. We employ an active balancing circuit that draws minimal current by using transistors. A diode is connected in series with each supercapacitor. A new balancing circuit that equalize the cells-voltage reduces energy consumption of supercapacitors. Voltage of operating WSN is applied 2.2-3.3V by DC/DC converter and supercapacitor voltage 2.2-5.1V. Maximum operating time of wireless sensor node is about 16 hours in full charging.