• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.243-244
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• 2008

The Velocity Autocorrelation Function (VAF) of the sodium ions is calculated for a range of temperature from 250K to 1000K and converted into the linear ac-conductivity and ac-susceptibility response via Fourier transformation. A peak is found in the conductivity around $6{\times}10^{12}Hz$ that has some of the character of a Poley absorption. Here it is shown to be due to an harmonically coupled site vibrations of the sodium atoms, which extend only over a limited range. At frequencies below the peak the conductivity tends towards a constant i.e. dc value corresponding to a constant flow of ions through the simulation cell. At high temperatures the conductivity due to this ion transport process behaves like a metal with an insulator to metal transition occurring around a specific temperature.

• 한국결정성장학회지
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• 제30권6호
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• pp.215-219
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• 2020

A-자리 결함 이중 Perovskite La1/3TaO3 단결정 시편을 제작하여 10~800 K 온도범위에서 유전특성을 조사하였다. 500 K 이하에서는 상유전성 거동이 나타났으며, 550 K 이상에서 유전이상과 유전상수의 열이력(thermal hysterisis)가 나타났다. 교류전도도 측정에 의한 활성화 에너지는 560 K 이하 영역에서 1.83 eV로 가장 크며, 560~690 K 영역에서 0.35 eV, 690 K 이상인 고온 영역에서 0.28 eV로 나타났다 이러한 결과로부터 500 K 이하 영역에서는 La3+-이온과 공공-자리가 무질서하게 배열하여 상유전상을 유지하며, 가장 높은 활성화 에너지를 나타낸 560 K 부근 영역에서는 La3+-이온이 공공-자리로의 전도 혹은 점프에 의한 재배열에 기인하여 유전이상이 나타난 것으로 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.322-325
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• 1991

An induction type small size electrostatic actor has been fabricated and tested using different rotor dielectric sheet type materials and 3 phase ac various frequencies ans volatages. It's maximum no-load speed was about 2800rpm at the applied voltage of 3030V and frequency of 47Hz for the rotor material of polypropylene sheet. The motor speed was increased linearly by increasing with an applied volatage and frequency, and it also influenced greatly by the electrical properties of rotor dielectric material of relative dielectric constant, resistivity and relaxtion time

• Composites Research
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• 제18권3호
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• pp.14-20
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• 2005

본 논문에서는 카본 블랙/에폭시 복합재료 적층판의 유전율에 대한 연구를 수행하였다. 유전율 측정은 $1\;GHz\~18\;GHz$의 주파수 영역에서 수행하였으며, 복합재료의 유전율은 카본 블랙 함유율의 주파수의 함수로 얻을 수 있었다. 유전율 및 전기 전도도의 주파수 특성은 Percolation 이론에서 제시된 경향을 만족하였다. 측정에 사용된 주파수 영역은 전기 전도도가 주파수의 함수관계를 가지는 최소 주파수인 임계주파수보다 크며, 복합재료의 유전율과 전기 전도도는 카본 블랙의 함유량과 일정한 관계를 가졌다. 본 연구에서는, 카본 블랙의 함유율에 따른 복합재료의 유전율을 모사하는 혼합법칙을 얻기 위하여 Lichteneker-Rother 방정식에 기초한 새로운 방법이 제시되었으며, 혼합법칙으로 계산된 복합재료 유전율 모사 결과는 실험적으로 얻은 유전율을 비교적 잘 모사하는 결과를 얻을 수 있었다.

• 전자공학회논문지A
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• 제31A권9호
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• pp.121-127
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• 1994

The capability for application of rf magnetron sputterred and post annealed BaTiO$_{3}$ thin films in dielectrics AC drived TFELD(thin film electroluminescent device) was investigated. The dielectric constant of the thin films slightly increased up to about 25 with increase fothe post annealing temperature in the range of 210$^{\circ}C$-480$^{\circ}C$. The dielectric loss was about 0.005-0.01 except for the high frequency range above 100kHz and nearly independent on post annealing temperature. The BaTiO$_{3}$ thin film used for TFELD was annealed at 480.deg. C and Si$_{3}$N$_{4}$ thin film was inserted between BaTiO$_{3}$, lower dielecrics and ZnS:Mn, phosphor layer for stable driving of the device and for fear of interdiffusion. Regardless of the frequency of the applied sine wave voltage, the threshold voltage of the prepared TFELD was 65volt and saturated brightness was about 3000cd/m$^{2}$ at 130volt(2kHz sine wave), 65volt above V$_{TH}$.

• 한국조명전기설비학회지:조명전기설비
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• 제5권2호
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• pp.77-83
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• 1991

비스페놀 A형 에폭시 수지에 $SiO_2$를 충진한 에폭시 복합재료의 단시간 절연파괴 특성을 충진제 첨가 함량의 변화, 주위온도(상온~[$190^{\circ}C$])의 변화 및 인가 전원의 종류별로 연구, 검토하였다. 연구결과, 절연파괴강도는 충진제 함량의 증가에 대해 일반적으로 감소하는 경향을 보였으며, 입자간 중심거리 d가 충진제함량이 증가함에 따라 감소하여 평균입자간격이 [$7.5\mu\textrm{m}$]이하가 되면 절연파괴 강도가 거의 일정한 값이 됨을 확인하였다. 또한, 교류전압을 인가하는 경우는 고온영역 ([$130^{\circ}C$]) 이상에서 충진된 에폭시수지가 무충진 에폭시수지보다 절연파괴강도가 증가하였다.

• Transactions on Electrical and Electronic Materials
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• 제8권6호
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• pp.278-282
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• 2007

In the complex insulation system that is used in extra high voltage(EHV) devices, according to the trend for electric power equipment of high capacity and reduction of its size, macro interfaces between two different bulk materials which affect the stability of insulation system exist inevitably. In this paper, the dielectric strength decrease of the macro interfaces between epoxy and ethylene propylene diene terpolymer(EPDM) was estimated by using the applied voltage to breakdown time characteristics. Firstly, the AC short time dielectric strength of specimens was measured at room temperature. Then, the breakdown time was measured under the applied constant voltage which is 70% of short time breakdown voltage. With these processes, the life exponent n was determined by inverse power law, and the long time breakdown voltage can be evaluated. The best condition of the interface was LOS(low viscosity(350 cSt) silicone oil spread specimen). When 30 years last on the specimens, the breakdown voltage was estimated 44% of the short time breakdown voltage.

• 대한전기학회논문지
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• 제45권2호
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• pp.235-241
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• 1996

In this paper dielectric and electrostrictive strain properties of (1-y-x)Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$-PbTiO$_{3}$$-yPbTiO_{3}-xSrTiO_{3}[(1-y-x)PMN-yPT-xST]$ ceramics fabricated by using columbite precursor method have been investigated with the substitution of SrTiO$_{3}$(ST). Dielectric constant of the specimens increased with the increase of ST content up to 5[m/o] and decreased with further substitution of ST. And the pyrochlore phase decreased with the increase of ST content up to 5[m/o] in XRD analysis. The elimination of the pyrochlore phase improved dielectric constants. The electrostrictive strains generated by AC electric field have the highest value at 5[m/o] SrTiO$_{3}$ addition and the hysteresis of strain ranged from 12 to 20[%]. The electrostrictive strain at various temperature investigated in the temperature range of $-50[^{\circ}C]~74[^{\circ}C].$ In higher temperature than phase transition region, it showed paraelectric property which shows very small hystersis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.227-232
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• 1991

Silicone resin which is made from silicone(Si) is well known by its heat-resistant property. Its good heat-resistant enables silicons resin being used in high temperature (up to $200^{\circ}C$) heavy-dury environment for electric insulation. This paper has dealed with the electrical properties of silicone resin such as dielectric constant and tan ${\delta}$ with heat treatment temperature $(200^{\circ}C{\sim}450^{\circ}C)$. To investigate the electrical insulation of silicone resin, dielectric strength by A.C and anti-tracking properties under both AC and D.C have been performed.

• 전기의세계
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• 제20권3호
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• pp.27-31
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• 1971

The main focus of this paper is on the study of the radiation effect upon the electrical property of a A-Kind insulator which is one of the organic insulators. The varnished cloth is so typical of the A-Kind insulators as to be selected for a sample. AC and Impluse voltage is applied to the variable Gamma ray irradiated dose samples with the constant time duration and the dielectric breakdown voltage are measured from the sample. The experimental data of the dielectric breakdown voltage are considerably decreased. The above conclusion is useful for the selection and application of the orgainc insulators under the irradiation effects.