• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.437-440
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• 2000

In this study, the interfacial dielectric breakdown phenomenon of interface between Epoxy and Rubber was discussed, which affects the stability of insulation system of power delivery devices. The breakdown strength of specimens are observed by applying high AC voltage at the room temperature. The breakdown times under the constant voltage below the breakdown voltage were gained. As constant voltage is applied, the breakdown time is proportion to the breakdown strength. The life exponent n is gained by inverse power law and the long time breakdown life time can be evaluated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.190-193
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• 2010

Various power semiconductor devices have been developed and evolved since 1950s. Among them, IGBT is the most developed power semiconductor device which has high breakdown voltage, high current conduction and suitable switching speed which perform trade-offs between each other. In other words, there are trade-offs between a breakdown voltage and on-state voltage drop, and between on-state voltage drop and turn-off time. In this paper, the new structure is proposed to improve a trade-off between a breakdown voltage and on-state voltage drop. The proposed structure has a trench collector and this trench collector induces an accumulation layer at the bottom of an n-drift region during off-state. And this accumulation layer prevents expansion of depletion layer so that trapezoidal electric field distribution is performed in the n-drift region. As a result of this, breakdown voltage is increased without increasing on-state voltage drop. The electrical characteristics of the proposed IGBT is analyzed and optimized by using representative device simulator, TSUPREM4 and MEDICI. After optimization, the electrical characteristics of the proposed IGBT is compared with NPT IGBT which have the same device thickness. As a result of this, it can be confirmed that the proposed structure increases the breakdown voltage of 800 V than that of the conventional NPT IGBT without increasing the on-state voltage drop.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.359-362
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• 1998

Electrical breakdown characteristics of liquid nitrogen(LNd used as both coolant and insulator for high $T_c$ superconductor system is very important. This paper presents dynamic breakdown characteristics of liquid nitrogen by quench penomena of thermal bubble under high electric field. As the result, the breakdown mechanism of $LN_2$ depends on thermal bubble effect. The breakdown voltage decreases slightly with increasing heating. In the Electrode arrangement, electrical breakdown voltage of horizontal arrangement appears lower than that of vertical arrangement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.1039-1044
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• 2000

Breakdown voltage model and expertiments are compared for discharge cells of AC plasma display panel. In the model, discharge paths are assumed to be initial electric field lines and the one-dimensional continuity equation is applied to the charged particle transport at each field line. The comparisons are performed in the wide range of gas pressure (50-600torr), Xe partial pressure over total pressure (1-6%), sustain electrode gap(100-1000$\mu\textrm{m}$), wall height(130, 300$\mu\textrm{m}$), and voltage pulse width(2-6${\mu}$s). The presented breakdown voltage model well agree with experiments in the above wide range. The increase of breakdown voltage with the decrease of the width(L) of protruding electrode is also described by the model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.366-367
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• 2008

SF6 widely used as insulating gas is rising as the environment problem. For decreasing this greenhouse gas, electrical breakdown characteristics of vacuum with air are studied in non-uniform field. The gap of needle to plane was 0.5mm, 0.8mm. The pressure of vacuum the range of 10^-4-10^-5torr. The diameter of a plane made of the stainless steel is150mm. As a result of the experiment, the breakdown voltage is increased about electrode gap distance increased. The electrode material influenced breakdown voltage in vacuum.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.984-989
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• 2011

Electrical insulation is one of the most important part in a high voltage apparatus. Recently, researchers are interested in the environmental friendly vegetable oil from environmental viewpoint. Accelerated aging transformer insulating material in vegetable oil was compared to that of mineral oil. Accelerated aging oil samples produced in the oven at $140^{\circ}C$ for 500, 1000, 1500, 2000hours. And Real transformer insulation oils samples of vegetable oil and mineral oil were aged by thermal cycles repeating from $30^{\circ}C$ to $120^{\circ}C$. Samples were analyzed at 42, 63, 93, 143, 190, 240, 300 cycles. The mineral and vegetable insulating oils were investigated for breakdown voltage, water content, total acid number, viscosity, volume resistivity, insulating paper and oil permittivity, and dissolved gas analyses. The breakdown voltage of the vegetable insulating oil is higher than that found for the mineral oil; the accelerated aging progress decreased the breakdown voltage. The vegetable oil had a higher water saturation than the mineral oil; the vegetable oil has the superior water characteristics and breakdown voltage. And high viscosity of vegetable oil, care has to be taken, especially when designing the cooling system for a large transformer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.280-285
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• 2023

A breakdown voltage and breakdown electric field of the transformer insulating oil of liquid dielectric were studied in uniform electric field and non-uniform electric field and the transformer insulating oil was observed by the process reached breakdown. Insulation performance evaluation of the liquid dielectric was evaluated at the electrode spacing of 2.5 mm under the conditions of domestic and international standards (KS C IEC 60156), so a comparative review was conducted at the electrode spacing of 2.5 mm. When the electrode spacing is 2.5 mm, the average breakdown voltage is 38.5 kV for sphere-sphere electrodes, 26.6 kV for plate-plate electrodes, 22.9 kV for needle-needle electrodes, and 24.3 kV for sphere-needle electrodes. 23.7 kV for the sphere-plate electrode, and 20.7 kV for the needle-plate electrode. From these results, it can be seen that the average value of the breakdown voltage at the electrode spacing of 2.5 mm, in ascending order, is sphere-sphere, plate-plate, sphere-needle, sphere-plate, needle-needle and needle-plate. It was found that the breakdown voltage of the unequal field was lower than that of the equal field.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.363-369
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• 2017

This paper presents the experimental results related to soil ionization and electrical breakdown in a concentric hemispherical electrode system under lightning impulse voltages. Dynamic voltage-current and impedance-time characteristics of soil ionization were measured and analyzed. Also the electrical breakdowns of the soil gap were investigated. The time-lag to the peak current corresponds to the soil ionization propagation. The time of ionization propagation in wet sand is found to decrease with increasing the impulse currents. A drastic decrease in ground resistance was observed during the impulse current spreading in sand. The electrical breakdown appears at the wave tail of impulse voltage and results in a wide scatter in V-t curves. The voltage-current curves have a fan-like shape attributed to ionization processes which result in increasing current and decreasing voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.286-289
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• 2003

In the case of high voltage devices, junction termination plays an important role in determining the breakdown voltage of the device. The mesa junction termination has been demonstrated to yield nearly ideal breakdown voltage for 6H-SiC p-n junctions. However, such an approach may not be attractive because of the nonplanar surface, which is difficult to passivate. Moreover, In case of 4H-SiC, ideal breakdown voltage could not be achieved using mesa junction termination. For 4H-SiC planar junction termination technique is more useful one rather than mesa junction termination. In this paper, breakdown characteristics of the 4H-SiC device with planar junction termination, such as FLR(Field Limiting Ring), FP(Field Plate) and JTE(Junction Termination Extension), is presented. In the case of the FLR, breakdown voltage of 1800V is obtained. And breakdown voltage of 1000V and 1150V is also obtained for the case of FP and JTE case, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.4
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• pp.214-217
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• 2017

An IGBT (insulated gate bipolar transistor) device has an excellent current-conducting capability. It has been widely employed as a switching device to use in power supplies, converters, solar inverters, and household appliances or the like, designed to handle high power. The aim with IGBT is to meet the requirements for use in ideal power semiconductor devices with a high breakdown voltage, an on-state voltage drop, a high switching speed, and high reliability for power-device applications. In general, the concentration of the drift region decreases when the breakdown voltage increases, but the on-resistance and other characteristics should be reduced to improve the breakdown voltage and on-state voltage drop characteristics by optimizing the design and structure changes. In this paper, using the T-CAD, we designed the NPT-IGBT (non punch-through IGBT) and FS-IGBT (field stop IGBT) and analyzed the electrical characteristics of those devices. Our analysis of the electrical characteristics showed that the FS-IGBT was superior to the NPT-IGBT in terms of the on-state voltage drop.