• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.465-466
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• 2007

In electrode-less lamp, The key point in creating an efficient light source based on RF discharge is to minimize the RF power loss in the RF coupler which for Anderson's type of RF lamp is due to losses in the ferrite core. This loss depends on the particular ferrite material, its size, geometry, frequency in this kind of inductive lamp shows that the correct choice of discharge current has a crucial effect on the core loss. In this study, we measured Ferrite temperature in normal state, then analyzed electrical and optical characteristics according to ferrite shape. We were able to know that was ferrite of the antenna had relate closely with temperature and luminous of the lamp. Also we appraised temperature and electrical, optical properties during turn on the lamp.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.228.2-228.2
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• 2016

The triggered vacuum switch (TVS) discharges high current through two processes. In the first process, an igniting plasma is generated at a trigger system, and the next process that a main discharge is taken place sequentially at a six-gap rod electrode within a few microsecond. In general, a triggered voltage producing the igniting plasma is increased. However, after several hundred shots, it goes down and stable, in our experiment the trigger voltage is about 5 kV after 250 shots. This triggered characteristics comes from the ceramic insulator which is covered by an electrode material, therefore we have focused on the first igniting plasma process. The igniting plasma has been generated at the surface of a ceramic insulator under a strong electric field. The electric field can be increased through modifying geometries of trigger components which compose of a trigger pin, a ceramic insulator and an enclosed holder. We fabricated not only two types of trigger pin which are a plane head and an umbrella head type, but two different holders which are a concave and a convex type. In this paper the result that the dependency of geometries for these four combined types is included, but the study of the ceramic insulator is not. The research of the ceramic insulator will be announced in the other paper.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.254-257
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• 1997

In this paper, we investigated the effects of gap length and tip radius influenced in breakdown of mineral based insulation oil Electrode system was needle-plane geometry It is to model conductive extrusions in oil filled electrical power apparatus. The tip radius of needle electrode was 5, 10, 20 and 25${\mu}{\textrm}{m}$, respectively. We measured breakdown voltage for each of tip radius with increasing electrode gap, 2mm to 12mm. It was calculated electrical breakdown strength at tip using Mason\`s equation from breakdown voltage As gap lenght increased. breakdown strength increased linearly. But, as tip radius of needle increased, breakdown strength decreased exponentially. It can be explained by tole phenomenon that electron is easily injected, as tip radius increases, and effective work function decreases. When appling DC voltage. breakdown 7tr7ilgtll was higher wheal polarity of needle was negative than positive. It is because of the space charge effect ill accordance with the influence of liquid motion.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.184.2-184.2
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• 2014

Recent advances in the synthesis and characterization of nanoscale objects provided us with the atomistic understanding of charge transport through single molecular junctions. The representative examples are the mechanically controlled break junction technique and STM or conducting AFM junction techniques. Theoretical studies have been reported on the dependence of electronic charge transport on the geometry of molecule-electrode contacts, the critical element toward the realization of molecular electronics. In this report, we will clarify the puzzling discrepancies between theoretical predictions and experiments.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.333-336
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• 2009

A series of microcavity plasma devices having various electrode geometries were investigated for the display and lighting applications. Addressable, self-assembled Al/$Al_2O_3$ electrodes were fabricated in a thin, flexible single sheet of Al foil. And, enhanced luminance and efficient microplasmas are achieved by precise control of the cross-sectional geometry and surface morphology of the cavities within the microplasma devices. New microdischarge system fabricated in various substrates will be introduced.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1113-1116
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• 1998

A new graphite intercalation compound (GIC), n-octylammonium tetrachlorofeffate(Ⅲ)-graphite, has been derived from well-known ferric chloride graphite intercalation compound. X-ray diffration study shows that the basal spacing of this new GIC is 20.8 Å. In order to investigate the local geometry around the iron atom in the graphite layers, X-ray absorption spectroscopy experiments were performed. The first discharge capacity of its exfoliated form is found to be 862 mAh/g, which is more than double the value of pristine graphite (384 mAh/g). Such a drastic increase implies that the exfoliated graphite is a promising electrode material.

• Journal of Biosystems Engineering
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• v.41 no.1
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• pp.60-65
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• 2016

Purpose: The necessity for precise manipulation of bioparticles has greatly increased in the fields of bioscience, biomedical, and environmental monitoring. Dielectrophoresis (DEP) is considered to be an ideal technique to manipulate bioparticles. The objective of this study is to develop a DEP microfluidic device that can trap fluorescent beads, which mimic bioparticles, at the low voltage and frequency of the sinusoidal signal supplied to the microfluidic device. Methods: A DEP microfluidic device, which is composed of polydimethylsiloxane (PDMS) channels and interdigitated electrode networks, is fabricated to trap fluorescent beads. The geometry of the interdigitated electrodes is determined through computational simulation. To determine the optimum voltage and frequency of the sinusoidal signal supplied to the device, the experiments of trapping beads are conducted at various combinations of voltage and frequency. The performance of the DEP microfluidic device is evaluated by investigating the correlation between fluorescent intensities and bead concentrations. Results: The optimum ratio of the widths between the negative and positive electrodes was 1:4 ($20:80{\mu}m$) at a gap of $20{\mu}m$ between the two electrodes. The DEP electrode networks were fabricated based on this geometry and used for the bead trapping experiments. The optimum voltage and frequency of the supplied signal for trapping fluorescent beads were 15 V and 5 kHz, respectively. The fluorescent intensity of the trapped beads increased linearly as the bead concentration increased. The coefficient of determination ($R^2$) between the fluorescent intensity and the bead concentration was 0.989. Conclusions: It is concluded that the microfluidic device developed in this study is promising for trapping bioparticles, such as a cell or virus, if they are conjugated to beads, and their concentration is quantified.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.615-618
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• 2004

The piezoelectricity and polarization of multilayer ceramic actuators, being designed to stack ceramic layer and electrode layer alternately, were investigated under a consideration of geometry, the thickness ratio of the ceramic layer to electrode layer The actuators were fabricated by tape-casting of $0.42PbTiO_3-0.38PbZrO_3-0.2Pb(Mn_{1/3}Nb_{2/3})O_3$ followed by laminating, burn-out and co-firing process. The actuators of $5\times5mm^2$ in area were formed in a way that $60{\sim}200{\mu}m$ thick ceramics were stacked 10 times alternately with $5{\mu}m$ thick electrode. Increase in polarization and electric field-displacement with increasing thickness ratio of the ceramic/electrode layer and thickness/cross section ratio were attributed to the change of $non-180^{\circ}/180^{\circ}$ domain ratio which was affected by the interlayer internal stress and Poisson ratio of ceramic layer. The piezoelectricity and actuation behaviors were found to be dependent upon the volume ratio (or thickness ratio) of ceramic layer relative to ceramic layer. Concerning with the existence of internal stress, the field-induced polarization and deformation were described in the multilayer actuator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.3
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• pp.51-56
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• 2001

In this paper, the effect of magnetic field on corona discharge phenomena was experimentally investigated in the needle-plate electrode geometry. Needle-plate geometry discharge system with magnetic field at a right angle to the electric field was made. The corona discharge characteristics with magnetic field were investigated and compared with the corona characteristics without magnetic field in atmospheric pressure. As a result, in case of positive DC corona discharge with magnetic field, corona discharge zone was significantly wider, corona current was lower, and breakdown voltage was higher than those without magnetic field. However, in case of negative DC corona discharge with magnetic field, corona current was slightly higher and breakdown voltage was lower than those without magnetic field. It is thought that this result is due to cyclotron motion of charged particles such as electron and ion by magnetic field.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.12
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• pp.673-678
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• 2000

The dielectric barrier discharge(DBD) is a common method to create a nonthermal plasma in which electrical energy is used to create electrons with a high average kinetic energy. The unique aspect of dielectric barrier discharges is the large array of short lifetime(10ns) silent discharges created over the surface of the dielectric. A silent discharge is generated when the applied voltage exceeds the breakdown voltage of the carrier gas creating a conduction path between the applied electrode and grounded electrode. As charge accumulates on the dielectric, the electric field is reduced below the breakdown field of the carrier gas and the silent discharge self terminates preventing the DBD cell from producing a thermal arc. In fact, the most significant application of dielectric barrier discharges is to generate ozone for contaminated water treatment. Therefore, experiments were perfomed at 1∼2[bar] pressure using a coaxial geometry single dielectric barrier discharge for ozone concentrations and energy densities. The main result show that the concentration and efficiency of ozone are influenced by gas nature, gas quantity, gas pressure, supplied voltage and frequency.