• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.288-288
• /
• 2009

We have studied polarity effects of dielectric anisotropy effects on electro-optical characteristics of a twisted nematic mode driven by fringe electric field, which has wide viewing angle characteristics. Our device is designed as normally black mode between parallel polarizers. The perfect polarization conversion of incident light, which passes through a polarizer, is achieved, when it passes through the twisted liquid crystal (LC) layer. If an electric field is applied, the LC molecules with a positive (or negative) dielectric anisotropy rotate parallel (or perpendicular) to the horizontal component of a fringe electric field as increasing transmittance. From the calculated results, enhanced transmittance of the fringe field-twisted nematic (FF-TN) mode with positive dielectric anisotropy of + 8.2 can be obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.410-413
• /
• 2002

In this paper, the performance of high-k dielectric is modeled by observing electrical characteristics through the process and device simulation. ZrO$_2$ on Si substrate is used as test structures to characterize the current-voltage and the capacitance-voltage profiles. In order to verify the simulation results, the experimental results are used as a reference. Based on the modeling results, the methodology can be a potential tool to predict the characteristics of the ZrO$_2$ dielectric.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.49-49
• /
• 2010

In this paper, a full scaled gas discharge chamber was designed and fabricated for evaluating the dielectric performance of SF6/N2 mixture gases. And it describes work on AC and lightning impulse dielectric characteristics of SF6/N2 mixture insulation gas from experiments and full scale models.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.479-481
• /
• 1995

This paper presents a method witch tan improve the dielectric recovery characteristics of UHV class gas circuit breakers by changing the nozzle shape. To calculate the dielectric recovery voltage between electrodes, the flow field and electric field analysis in a 362kV model interrupter has been performed with the commercial programs, RAMPANT and FLUX2D, respectively. As a result, we found that the nozzle shape affects the characteristics of dielectric recovery between electrodes and obtained great improvement of it by the changing the downstream nozzle shape.

• Proceedings of the KIEE Conference
• /
• 1993.07a
• /
• pp.24-26
• /
• 1993

The dielectric properties of pressboard depend on the chemical and fine structures as well as on the macroscopic structure of pressboard. The investigate on the dielectric characteristics of pressboard therefore, provides an important approach to an understanding of the correlation between the characteristics and the structure of pressboard. The purpose of this research is to investigate the dielectric properties of pressboard.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.65-68
• /
• 2000

Polyethylene, has long history and is widely used, was researched due to good electrical properties by many authors. But PE under stress has the critical defects of space charge accumulation and tree growth, so various methods such as catalyst, additives and blend to improve these problems have been execute, of which we selected blending method. As in our previous papers we investigated electrical conduction, dielectric and AC dielectric breakdown characteristics, we did DC dielectric breakdown characteristics in this paper. We selected pure LLDPE, pure EVA and LLDPE films mixed with EVA as specimens, which were mixed with the weight percentages of 50, 60, 70 and 80[wt%] to be thin film. DC applying voltage speed was 500[V/sec]. The relation between dielectric breakdown characteristics and the variations of super structure due to mixing was investigated, and especially trap level at amorphous region, threshold energy increment of conductive electron at free volume were considered.

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.558-560
• /
• 1993

The dielectric properties of pressboard depend on the chemical and fine structures as well as on the macroscopic structure of pressboard. The investigate on the dielectric characteristics of pressboard, therefore, provides an important approach to an understanding of the correlation between the characteristics and the structure of pressboard. The purpose of this research is to investigate the dielectric properties of pressboard.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.08a
• /
• pp.64-68
• /
• 2002

According to the increasing power demand for the future construction of many underground cables will be required. However, construction of new ducts for power cables will be more difficult. Therefore, research work for realizing the high temperature superconducting(HTS) cable has advanced, where the development of electrical insulating system at cryogenic temperature is one of the major researches. For an electrical insulation design of HTS cable, it is important to understand not only breakdown but also partial discharge and dielectric loss($tan{\delta}$) in liquid nitrogen/paper composite insulation system. In this paper, we investigated breakdown characteristics in liquid nitrogen/paper composite insulation system for the application to HTS cable. And, we studied the breakdown characteristics of the multi-layer and butt gap of the insulation papers in liquid nitrogen. Also, we measured dielectric loss($tan{\delta}$) of the mini-model Cable made of TERLAM IPP.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.4
• /
• pp.54-59
• /
• 2003

In this paper, a cylindrical dielectric antenna with dielectric clad is designed and analyzed. Design parameters of a cylindrical dielectric resonator antenna are calculated from the wave equation of cylindrical dielectric. The variations of characteristics of the antenna are analyzed as varying the thickness and the relative permittivity of its clad. From the results, when the ratio of the outside radius of the dielectric clad to the radius of the cylindrical dielectric is 1.3 and the relative permittivity of the dielectric clad is one-third of the cylindrical dielectric resonator antenna, the relative bandwidth of the antenna is 49%, which is improved by 2.3 times than the cylindrical dielectric resonator antennas. However, the thickness and the relative permittivity of the dielectric clad have not effect on the radiation pattern, beamwidth and gain of the antenna.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.3
• /
• pp.978-983
• /
• 2014

The polymer nano composite possess good priority recently for engineering applications. Especially the electrical insulating materials attract the high performance of nano composites. In this work the ballmill synthesiation process of nano sized Alumina ($Al_2O_3$), the preparation of new nano composite material with an content of enamel and synthesized Alumina as 1wt%, 3wt% and 5wt%. Experimental investigation has been carried out for the prepared nano composites materials with respect to dielectric parameter measurements such as dielectric loss (tan ${\delta}$), dielectric constant (${\varepsilon}$), dielectric strength under various temperature. The partial discharge level also measured for all the samples and the PD inception voltage is also observed and compared. Weight loss of the material has been analyzed through TGA. It has been experimentally proved that 3wt% of Alumina nano filler added enamel has significant improvement in the dielectric and thermal properties.