• Journal of the Korean Society of Safety
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• v.26 no.6
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• pp.26-30
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• 2011

Experimental investigations were performed to examine the effects of different electrostatic discharge ignition energies on LPG/air mixture explosions in an explosion chamber. The chamber consisted of 500 mm in length, with a $100{\times}100mm^2$ cross section. Three different ignition energies were used: 0.30 mJ, 46 mJ and 98 mJ. Flame propagations were recorded by a high speed video camera. The results of flame speed and pressure obtained from the different ignition energies were discussed. It was found that as the energy increased, different flame initiations occurred. This caused the time interval in both the flame and pressure developments. It was also found that the flame speed and the pressure were less sensitive to both 0.30 mJ and 46 mJ, except for the ignition energy of 98 mJ.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.37.2-37.2
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• 2010

Electrostatic spray deposition is an innovative coating technique that produces fine, uniform, self-dispersive (due to the Coulombic repulsion), and highly wettable, atomized drops. Copper-indium salts are dissolved in an alcohol-based solvent, which is then electrostatically sprayed onto a moderately heated, molybdenum-coated substrate. Solvent flowrates range from 0.02 to 5 ml/hr under applied voltages of 1 to 20 kV yielding drop sizes around a few hundred nanometers. By comparing the scanning electron miscrscope images of coated samples, the substrate temperature, applied voltage, solvent flowrate, and nozzle-substrate distance are demonstrated to be the primary parameters controlling coating quality. Also, the most stable electrostatic spray mode that reliably produces uniform and fine drops is the cone-jet mode with a Taylor cone issuing from the nozzle.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.154-160
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• 2008

We investigated molecular polarity by using theoretical means and comparing empirical solvent polarity. Our approach employed electrostatic potentials at the molecular surface calculated by density functional methods. A number of molecular descriptors related to molecular polarities were computed from molecular surface electrostatic potentials. Among computed molecular descriptors, the most positive electrostatic potential provided the best correlation with the empirical solvent polarities. A regression equation was developed in order to predict molecular polarities of molecules whose experimental solvent polarities were unknown. The new regression equations were utilized in estimating solvent polarities of cubane derivatives which are considered important precusors of high-energy density meterials.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1819-1823
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• 1997

When flammable gases are mixed with air or oxygen in the explosion concentration range and are ignited by sufficiently large electrostatic discharge energy, they may explode causing severe disaster in workplaces. The minimum ignition energy (MIE) of single gas-air mixtures has been already investigated by many researchers, but the MIE of mixtures of more than three substances is not examined yet. The purpose of this study is to investigate the MIE of several three-component gas mixtures experimentally. The result of our experiment shows that the MIE of some gas mixtures is quite different from that we expected based on the characteristics of individual gas-air mixture.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.27-34
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• 2010

In a test duct with closed configuration, particle removal performance of an edge-plate type electrostatic precipitator (ESP) was evaluated at a high flow rate in $CO_2$ rich environments by changing gap distances between collection plates, concentrations of $CO_2$, particle sizes, types of electrodes, and types of power supplies. At the same experimental conditions, collection efficiency of particles with the mean particle size, 300 nm, decreased as the gap distance and $CO_2$ concentration increased because of low electrostatic force and low discharged current. In addition, as the particle size increased, the efficiency increased because of high charging rate of the large particles. With the electrode type which has higher surface area of a discharging plate and with the power supply which applied 25 kHz-pulsed DC voltages, the removal efficiency was high even in rich $CO_2$ condition due to high electrostatic force at the same power consumption.

• Journal of the Korean Vacuum Society
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• v.22 no.4
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• pp.198-203
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• 2013

Energy harvesting refers to converting ambient energy from our surroundings, which would be otherwise wasted, into useful electrical energy. A triboelectric energy harvester is a self-charged device for harnessing mechanical energy based on a coupled process of contact charging and electrostatic induction. In this research, we demonstrate simple fabrication of prototype triboelectric energy harvester using soft lithography and its electrical characterization. Triboelectric generation occurs between the two micro patterned layers of Au and PDMS. A micro pattern is simply replicated directly from the bottom layer to the top layer using soft-lithography without an extra transfer process. This generator can produce an output voltage of 2 V and output current of 20 nA.

• Applied Science and Convergence Technology
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• v.25 no.2
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• pp.36-41
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• 2016

Similarity and diversity of various quantum ring structures are investigated by classifying energy dispersions of three different structures: an electrostatic quantum ring, a magnetic quantum ring, and a magnetic-electric quantum ring. The wave functions and the eigenenergies of a single electron in the quantum ring structures are calculated by solving the Schrdinger equation without any electron-electron interaction. Magnetoconductance is studied by calculating a two-terminal conductance while taking into account the backscattering via the resonance through the states of the quantum rings at the center of a quasi-one dimensional conductor. It is found that the energy spectra for the various quantum ring structures are sensitive to additional electrostatic potentials as well as to the effects of a nonuniform magnetic field. There are also characteristics of similarity and diversity in the energy dispersions and in the single-channel magnetoconductance.

• Applied Science and Convergence Technology
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• v.25 no.6
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• pp.154-157
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• 2016

The energy dispersion and magnetization of a modified magnetic dot are investigated numerically. The effects of additional electrostatic potential, magnetic field non-uniformity, and Zeeman spin splitting are studied. The modified magnetic quantum dot is a magnetically formed quantum structure that has different magnetic fields inside and outside of the dot. The additional electrostatic potential prohibits the ground-state angular momentum transition in the energy dispersion as a function of the magnetic field inside the dot, and provides oscillation of the magnetization as a function of the chemical potential energy. The magnetic field non-uniformity broadens the shape of the magnetization. The Zeeman spin splitting produces additional peaks on the magnetization.

• Bulletin of the Korean Space Science Society
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• 1993.10a
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• pp.22-22
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• 1993

We developed the low energy electron detector (LEED) for KITSAT-B which was launched on September 26, 1998. The sensor head is mounted on the top of the satellite so that it can measure the precipitating electron flux along the Magnetic field line in the auroral zone at 820 km altitude. The detector system is composed of 4 parts : the electrostatic analyzer, the spira10on detector, the discriminator / Preamplifier, and the interface to the spacecraft. The analyzer limits the access to the spiraltron only to the electrons of certain energies which are determined by the electrostatic field across the two coaxial cylindrical analyzer plates. The energy spectrum of the detector in consideration is about 100 eV to 6.7 KeV, which is swept in 1.6 seconds and divided into 16 bins. It 81so is 1.6 second reset period after each swept, We will discuss the technical features of the system as well as the future observational schedule.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.625-626
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• 2008