• 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 Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.4
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• pp.26-33
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• 1993

The acoustic emission automatic detection system is developed to observe tree deterioration phenomena. Applying an alternating voltage of 15(kVnns) toXLPE tree specimens, many pulses of small amplitude are detected when the bush type tree developes branch type and a few pulses of high amplitude prcxluced as branch type propagated to bush type tree. Therefore, it is known that pulses having small amplitude operates as a destructive factor. It is observed that the skewness of the amplitude and the number of average pulses as distribution tendency of three dimension are characteristic quantity of AE pulses. As the trajectory of skewness is farther from the origin on the S-plane, it is more likely to breakdown.

• The Journal of Korean Physical Therapy
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• v.15 no.3
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• pp.153-165
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• 2003

This study was carried out to evaluate the body fat breakdown during topical seaweed extract treatment and in combination with the iontophoresis method to enhance skin absorption of lipolytic compounds. Of 14 female obesity subjects, 7 treated a gel types of seaweed extract only(control group) and 7 treated in combination with the iontophoresis(experimental group). Topical treatment of each sample was designed for 2 weeks, treated with 2 times a day about $10m{\ell}$ on the abdomen, triceps and thigh, respectively. Experimental group treat with the iontophoresis during 5 minutes immediately after topical treatment. After one and two weeks of topical treatment, measured body fat, skinfolds thickness, body circumference respectively. Then venous blood samples were taken and analyzed serum lipids. The results were as follows; 1) There were decrement of body weight, $\%$ of body fat, abdomen, triceps and thigh circumference and abdomen, triceps and thigh thickness between pre and post treatment in both group. These decrement were predominant in the iontophoresis treated group. Especially, there were $16\%$ of body fat decrement in the experimental group after two weeks iontophoresis treatment(control group VS experimental group = $33.54{\pm}2.70$ VS $28.37{\pm}3.38$, p<0.01). 2) There were decrement in total CHOL, LDL, TRIG and increment in HDL in both group. These phenomena were predominant in the iontophoresis treated group. CHOL decrement in the experimental group were significant after two weeks iontophoresis treatment(control group VS experimental group = $190.24{\pm}34.36$ VS $157.76{\pm}24.45$, p<0.001). These results suggest that the topical treatment of seaweed extract effective for fat breakdown and maximized in the combination with the topical seaweed extracts treatment and the iontophoresis.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.131-136
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• 2015

In this paper, prior to the flight model X-band dual-mode circular cavity filter required for the high power transmission of the observation payload in the geostationary satellite, the development model are designed and analyzed to show the analytical multipactor requirement margin. First of all, the multipaction breakdown power sensitivities were analyzed by changing the iris width and thickness within the filter, and through that the iris width and thickness was selected and then the multipaction threshold powers over the frequencies within the bandwidth were analyzed and the required margin of 8 dB was obtained. Also for the high power transmission filter, another important phenomena known as corona breakdown are analyzed for the iris width and thickness changes. Finally the development model manufactured was tested and the results met the key requirements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1175-1179
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• 2009

We analyze voltage characteristics of charged particle type display according to particle layers and cell gap between two electrodes and ascertain the aging effects by measuring the response time of particles with and without aging process. The threshold/driving/breakdown voltage is proportional to layers of charged particles and cell gap and the response time at driving voltage is faster than that of threshold and breakdown voltage because of different q/m of color and black particles. The analysis of response time is a method of estimation of optical characteristics, driving voltage and particle lumping and these results are promoted by aging process. We use the laser and photodiode to measure response time and optical properties. It has not been studied and reported to analyze the relationship of response time, threshold/driving/breakdown voltage, lumping phenomena, cell gap, and aging process for charged particle type display.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.3
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• pp.24-32
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• 2011

[ $SF_6$ ]gas, which has an excellent dielectric strength and interruption performance, is used in various applications such as gas insulated switchgear (GIS) in substations. However, since $SF_6$ has a high global warming potential (GWP), it is necessary to find an eco-friendly alternative insulation gas. In order to examine the possibility of using alternative insulation gases for $SF_6$ in power distribution system equipment, the dielectric strength and physical phenomena of dry air in a quasi-uniform electric field are investigated experimentally in this paper. As a result, the breakdown voltages for positive polarity are higher than those for negative polarity under impulse voltage applications. The negative 50[%] flashover voltage, $V_{50}$ of dry air under conditions above 0.4[MPa] gas pressure, is higher than 150[kV], that is the basic impulse insulation level of distribution equipment. The $V_{50}$ increases linearly with increasing the gas pressure, regardless of the waveform and polarity of the applied impulse voltages. The voltage-time curves are dependent on the rise time of the impulse voltage and gas pressure. Furthermore, streamer discharge was observed through light emission images by an ICCD camera under impulse voltage applications.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.117-122
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• 2007

LB method is one of the most interesting technique to arrange certain molecular groups at precise position relative to others. Also, the LB deposition technique can fabricate extremely thin organic films with a high degree of control over their thickness and molecular architecture. In this way, new thin film materials can be built up at the molecular level, and the relationship between these artificial structures and the properties of materials can be explored. In this paper, evaluation of physical properties was made for dielectric relaxation phenomena by the detection of the surface pressures and displacements current on the monolayer films of phospolipid monomolecular DLPC. Lipid thin films were manufacture by detecting deposition for the accumulation and the current was measured after the electric bias was applied across the manufactured MIM device. It is found that the phospolipid monolayer of dielectric relaxation takes a little time and depend on the molecular area. When electric bias is applied across the manufactured MIM device by the deposition condition of phospolipid mono-layer, it wasn't breakdown when the higher electric field to impress by increase of deposition layers.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.7
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• pp.331-337
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• 2001

With the increasing reliability of analysis schemes and the dramatically increased calculating speed, the computer simulation has become and indispensable process to predict the interruption capacity of circuit breakers. Generally, circuit breakers have to possess both the small current and large current interruption abilities and the circuit breaker designers need to evaluate its capacities to save the time and the expense. The analysis of small current and the large current interruption performances have been considered separately because the phenomena occurring in a interrupter are quite different. To analyze the dielectric recovery after large current interruption many physical phenomena such as heat transfer, convection and arc radiation, the nozzle ablation, the ionization of high temperature SF(sub)6 gas, the electric and themagnetic forces and so forth mush be considered. However, in the analysis of small current interruption performance only the cold gas flow analysis needs to be carried out because the capacitive current is to small that the influence from the current can be neglected. In this paper, an empirical equation which is obtained from a series of tests to estimate the dielectric recovery strength has been applied to a real circuit breaker. The results of analysis have been compared with the test results and the reliability has been investigated.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1699-1701
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• 1998

This paper was studied on the surface discharge characteristics on the solid insulators in the Liquid Nitrogen($LN_2$) at atmospheric pressure. Liquid Nitrogen has been widely used as a tooling and insulating materials for superconducting and cryogenic cable. Considering the effect of bubbles, we observed tracking Phenomena on the surface of solid insulators and investigated surface breakdown characteristics of several solid insulators.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.1
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• pp.1-12
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• 2001

Based on mixed-mode transient analyses utilizing a 2-dimensional device simulator, we have suggested the methodology to analyze the HBM ESD phenomena in CMOS chips utilizing NMOS transistors for ESD protection, and have analyzes the HBM discharge mechanisms in detail. Also the second breakdown characteristics in the protection device have been successfully simulated based on mixed-mode simulations, to explain the discharge mechanisms leading to device failure. To analyze the effects of the device structure changes on the discharge characteristics, we have compared the results of DC analyses and mixed-mode transient analyses, and have discussed about more robust designs of NMOS transistor structures against HBM ESD based on the analyses.