• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.12
• /
• pp.835-840
• /
• 2016

In this study, the electrostatic capacity and dielectric loss tangent for $20{\mu}m$ thick thermal conductivity silicone rubber which is heated at 80 degrees for 8 hours has been measured at temperature of $30^{\circ}C{\sim}170^{\circ}C$, frequency of 0.1~1 MHz. The results of degradation evaluation by this study are as follows. In low frequency, it found that the electrostatic capacity decreased with increasing temperature. On the other hand, it confirmed that the range of the electrostatic capacity narrowed with increasing frequency. It confirmed that there are the carboxylic acid structure and C-O bonding at range of wave number 1,000cm-1 to 1,300cm-1.

• 대한공업교육학회지
• /
• v.30 no.2
• /
• pp.115-122
• /
• 2005

For an analysis of dynamic behavior in carbon nanotube(CNT) which is widely used as micro and nano-sensors, an electrostatic force of CNT was investigated. For larger gaps in between sensor and electrode the van der Waals force can be ignored. The boundary condition in the CNT was assumed to clamped-clamped case at both ends. In this paper electrostatic force is expressed as linear equation along deflection using Taylor series. The first and second terms(${\zeta}_0$ and ${\zeta}_1$) of the linear equation are analyzed. Based on the simulation results nondimensional number ${\Phi}_0$ and ${\Phi}_1$ which came from ${\zeta}_0$ and ${\zeta}_1$ were decreased according to the increment of the gap. Reduction ratio of the second term ${\zeta}_1$ is increased up to 99% along to the increment of the gap. The higher order terms can be ignored and therefore, electrostatic force can be expressed using the first two terms of the linear equation. This results play an important role in analyzing the nonlinear dynamic behavior of the CNT as well as the pull-in voltage of simply supported switches.

• International Journal of Aeronautical and Space Sciences
• /
• v.16 no.2
• /
• pp.247-253
• /
• 2015

The components of an aero-engine gas path cannot be monitored in a timely way due to a lack of real-time monitoring technologies. As an attempt to address this problem, we have conducted research on a condition monitoring technology based on the charging characteristics of particles in an aero-engine gas path, and emphatically analyze the formation of particles in an aero-engine gas path, the charging mechanism of carbon particles and the factors that influence the charge quantity and polarity. The verification experiments are performed on the simulated experiment platform and a turbo-shaft engine test bench. The results show the carbon particles' carry charge, and an obvious change in the total electrostatic charge level in the aero-engine gas path due to the increased carbon particles produced by burning or abnormal metal particles; the charge number is related to the size of particles, and the bigger carbon particles carry a negative charge and metal particles carry a positive charge; the change in engine power can lead to an obvious change in the level of electrostatic charge in the gas path, and the change in electrostatic charge results from the extra carbon particles formed in the rich-oil burning process. The research provides a reference for establishing the baseline of electrostatic charge while the engine runs on different power. The study also demonstrates the validity of the electrostatic monitoring technology and establishes a base for developing the application of electrostatic monitoring technology in aero-engines.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.12
• /
• pp.1-7
• /
• 1997

Serious troubles may occur in electromagnetic equipments due to electrostatic discharge (ESD). The number of the damaging incidents are significantly increasing with the increased use of integrated semiconductor elements with loer operation pwoer. In order to examine the phenomena theoretically, this paper anlyzes properties of the transient electromagnetic fields rdiated by ESD. A new model is presented using the Rompe-weizel formula for the spark resistance. The numerical results of ESD fields are compared with the experimental data that were given by wilson-Ma.

• Journal of Advanced Marine Engineering and Technology
• /
• v.19 no.4
• /
• pp.34-41
• /
• 1995

The structure of premixed tubulent flames in a constant-volume vessel was investigated using a schlieren method and microprobe method. The schlieren method was used to observe the flame structure qualitatively. The microprobe method, which detects a flamelet by detecting its flame potential signal, was used to investigate the deeper flame structure behind the flame front. The flame potential signal having one to six peaks was obtained in the case of turbulent flames, each of them being regarede as a flamelet existing in the flame zone. Based on this consideration, the flame propagation speed, the thickness of the flame zone, the number of flamelets and the separation distance between adjacent flamelets in the flame zone were measured. Moreover, the thickness of flamelet which could not be attempted in the conventional electrostatic probe method was also investigated. The experimental results of this work suggest the existence of "reactant islands" in the reaction zone, and show that the averaged number of flamelets increases with an increase in the turbulence intensity and/or a decrease in the Damkohler number. The mean thickness of flamelet in the case of turbulent flames was found to be about two times compared to laminar values.ar values.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.10
• /
• pp.1442-1449
• /
• 2003

We investigated the amount of the toxic gases emitted from the Electrostatic Precipitators(ESPs), which are currently used as the indoor air cleaners. The existing wire-to-plate(WTP) and neddle-to-plate(NTP) types of ESP designs are considered as the experimental corona dischargers. Using the voltage, the polarity of wire, the number of needles of NTP as the input variables, we studied the generation characteristics of ozone and $NO_{x}$ and the particle removal efficiency in the ESPs. As the results, we found out that the concentration of ozone, $NO_{2}$ and $NO_{x}$ is increased with increasing the voltage and the number of needles, but the amount of NO is decreased. And we observed that the generation rates of ozone and $NO_{x}$ are mainly related with the corona region through the photographs. Finally the experimental results showed that the particle removal efficiency of ESP with WTP type charger is more superior to that with NTP type chargers at the same voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.04a
• /
• pp.133-138
• /
• 2000

MgO thin films were deposited using $Mg(tmhd)_2$ as a precursor dissolved in a solvent by electrostatic spray pyrolysis. When a pure tetra hydro furan was used as a solvent, a large number of particles appeared on the MgO thin film surface due to homogeneous nucleation. However, by adding 1-butyl alcohol or 1-octyl alcohol to THF, homogeneous nucleation was restricted and the number density of the large particles was also drastically reduced. X-ray diffraction analysis showed that the MgO films had a (100) preferred orientation regardless of the type of solvents used. Characterization using Fourier Transformed-Infrared and spectroscopic photometer revealed that the crystallized MgO thin films on the glass substrate had a high optical transmittance (> 85 %) in the visible range. Discharge characteristics of MgO thin films deposited by ESP method on an alternating-current plasma display panel were compared with a MgO thin film prepared by reactive radio-frequency planar magnetron sputtering.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.11
• /
• pp.1542-1547
• /
• 2003

Although dielectric barrier discharge (DBD) in air has been applied to a wider range of aftertreatment processes for HAPs (Hazardous Air Pollutants), due to its high electron density and energy, its potential use as precharging dust particles is not well known. In this work, we measured size distributions of bimodal aerosol particles and estimated collection efficiency of the particles by an electrostatic precipitator (ESP) using DBD as particle charger. To examine the particle collection with DBD charger, nano size particles of NaCl(20∼100nm) and DOS (50∼500nm) were generated by a tube furnace and an atomizer, respectively. For experimental conditions of 60㎐, 11㎸ and 60 lpm, the particle collection efficiency for the hybrid system was over 85%, based on the number of particles captured.

• Journal of Korean Society for Atmospheric Environment
• /
• v.10 no.1
• /
• pp.49-56
• /
• 1994

Electrostatic Precipitators( EP ) are widely used in industry for controlling the emission of particulate pollutant Recently, a number of researches have been conducted to solve performance and reliability problems of EP, As a result of researches in the laboratory and of pilot scale, a technology of wide-pitch-spacing has been successfully applied to full scale units. It has been known that the wide-pitch-spacing can reduce the capital cost of newly installed precipitators, and the cost of rebuilding existing uints. In this paper, a systematic study was performed to develop a wide-pitch electrostatic precipitator. The study includes experimental and numerical work on the following : Particle collection characteristics for a bench-scale unit; gas flow characteristics( temperature and velocity distributions): other EP operating variables such as electric Power supply/control. The results are applied directly to design of wide-pitch-spacing EP and the developed numerical model was found to be a good argreement with the experimental results. The EHD simulation program is necessary to design the high efficiency EP.

• Journal of Korean Society for Atmospheric Environment
• /
• v.18 no.5
• /
• pp.345-353
• /
• 2002

A study of polydispersed aerosol dynamics by Electrostatic Precipitator (ESP) was carried out. The log-normal particle size distribution was assumed and moment method was considered. In order to apply moment method in Deutsch-Anderson equation, Cunningham slip correction factor and Cochet's charge equation were simplified for certain range of particle size. The three parameters, which explain the particle size distribution, such as total number concentration, geometric mean diameter, and geometric standard deviation were considered to derive the analytic solution. The obtained solution was compared with available numerical results (Bai et al., 1995). The comparison of the numerical and analytic results showed a good agreement.