• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1497-1499
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• 1997

This paper dealt with the surface aging characteristics of silicone rubber used as the surface material of outdoor polymer insulators under accelerated aging condition. There are many aging factors in natural environment. In this paper, the silicone rubber were accelerated to evaluate their performance against salt fog, that is, they were dipped in pure water and salt water under boiling condition. Then, contact angle and SEM(Scanning Electron Microscope) were used to estimate surface hydrophobicity, and dielectric loss($tan{\delta}$) and surface leakage current were measured to observe the electrical characteristics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.420-422
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• 2003

Aging and failure of motor insulation depend on the stresses imposed on it. The insulation life time depends on the severity of the stresses. The electrical aging by transient surge is very important to traction motor in EMU(electric multiple unit). This paper Presents the insulation characteristics of stator coil by transient surge from inverter. There are several nondestructive tests available for checking the condition of motor insulation, the probable extent of aging,. and the rate of which aging is taking pace. So the insulation characteristics of stator coil were each analyzed by measurement of leakage current, dielectric loss($tan{\delta}$), capacitance, polarization index(PI) and partial discharge. The method of diagnosis is able to analyze the aging condition and Predict the life of the traction motor in EMU.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.406-408
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• 1999

캐패시터(capacitor)의 고주파(수십MHz) 전기장에서 유전손실(dielectric loss)에 의한 유리의 용융 및 합성에 관한 이론적 고찰이 수학적 모델에 의하여 이루어졌다. 유전 가열법에 있어서 캐패시터에 놓여진 유전체가 흡수하는 에너지는 용융인자(전압, 주파수)와 피시물(유리)의 전기, 물리적 성질[유전율(${\epsilon}$). power factor($tan{\delta}$)]에 의존한다. 본 연구에서는 이러한 물성들의 온도 의존성뿐만 아니라 외부로의 열손실 등이 조사되었으며, 특성 분석을 통해 최적의 용융 모델을 설계하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.623-627
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• 2003

Aging and failure of motor insulation depend on the stresses imposed on it. The insulation life time depends on the severity of the stresses. The electrical aging by transient surge is very important to traction motor in EMU(electric multiple unit). This paper presents the insulation characteristics of stator coil by transient surge from inverter. There are several nondestructive tests available for checking the condition of motor insulation, the probable extent of aging, and the rate of which aging is taking place. So the insulation characteristics of stator coil were each analyzed by measurement of leakage current, dielectric loss($tan{\delta}$), capacitance, polarization index(PI) and partial discharge. The method of diagnosis is able to analyze the aging condition and predict the life of the traction motor in EMU.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1285-1287
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• 2003

The aging of the insulation reduces the electrical and mechanical strength of the insulation. At same point, a voltage surge or mechanical shock from a traction motor start will fracture or break down the insulation. To achieve the expected life usually requires extensive laboratory evaluation of the insulation systems and the use of accelerated aging tests. There are several nondestructive test available for checking. the condition of motor insulation, the probable extent of aging, and the rate of which aging is taking place. So the insulation characteristics of stator coil were each analyzed by measurement of dielectric loss($tan{\delta}$), capacitance and partial discharge. The method of diagnosis is able to analyze the aging condition and predict the life of the traction motor.

• 한국세라믹학회지
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• 제43권2호
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• pp.92-97
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• 2006

Dolomite type $BaSn(BO_3)_2$ ceramics with rhombohedral crystal structure has been synthesized via solid state reaction route. Dielectric properties were measured for the samples sintered at $1050\~1200^{\circ}C$ for 2 h in air. Dielectric constant, loss tangent, and temperature coefficient were increased with sintering temperature due to the evolution of $BaSnO_3$, secondary, phase. Optimum dielectric properties were obtained at the $BaSn(BO_3)_2$ ceramics sintered at $1100^{\circ}C.\;CuO/Bi_2O_3$ was added to $BaSn(BO_3)_2$ ceramics to lower the sintering temperature for LTCC application, then Co and Fe-based coloring agents were added for colorizing the LTCC tape. Typical dielectric properties of $BaSn(BO_3)_2$ ceramics with $5 wt\%\;CuO/Bi_2O_3\;and\;3wt\%$ Co-coloring agent that sintered at $900^{\circ}C$ were $\varepsilon_r=9.89,\;tan{\delta}=0.92\times10^{-3},\;and\;TCC=112ppm/^{\circ}C$. Thus obtained LTCC tape was co-fired with Ag paste for compatibility test and revealed no sign of Ag reaction with the ceramics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.30-30
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• 2008

Lead-free piezoelectric ceramics 0.97$(Na_{0.5}K_{0.5})NbO_3$-0.03Ba$(Ti_{1-x}Sn_x)O_3$ [NKN-BTS-x] ceramics doped with 1 mol% $MnO_2$ have been fabricated by a sintering technique with muffling. The $MnO_2$-doped NKN-BTS-x ceramics with x$\leq$0.2 have pure orthorhombic perovskite structure at room temperature. The dense microstructure was developed with grain growth as an increase of amount of Sn. Moreover, the addition of Sn was found to have a significant influence on piezoelectric properties. In particular, the $MnO_2$-doped NKN-BTS-0.1 ceramics showed improved piezoelectric properties of piezoelectric constant ($d_{33}$=145pC/N), relatively large electromechanical coupling factor ($k_p$=43%), dielectic constant (${\varepsilon}^T_{33}/{\varepsilon}_0$=676) dielectric loss (tan$\delta$=1.3%).

• 한국전자파학회논문지
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• 제23권2호
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• pp.159-168
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• 2012

본 논문에서는 IR-UWB(Impulse Radio Ultra Wideband) 시스템 응용을 위한 앤티포달 비발디 안테나를 설계하고, 시간 및 주파수 영역에서 나노 초 단위의 초광대역 임펄스 신호 전송을 위한 IR-UWB 안테나 성능 평가를 수행하였다. 설계된 앤티포달 비발디 안테나는 저가 생산이 가능한 두께 1.6 mm, 유전율 ${\epsilon}_r=4.7$, $tan{\delta}=0.002$인 FR-4 기판을 이용하여 제작하였다. 제작된 안테나는 무반사실에서 주파수 영역 파라메타인 반사 손실, Far 필드방사 패턴을 측정하였다. 또한, 시간 영역에서 나노 초 단위의 임펄스 신호 전송에 따른 펄스 충실도 분석을 수행하여 UWB 대역에서 안정적으로 초광대역 신호 전송이 가능함을 증명하였다. 본 논문에서 설계/제작된 앤티포달 비발디 안테나는 낮은 왜곡과 양호한 방사 특성을 갖고, 나노 초 단위의 초광대역 임펄스를 방사 또는 수신할 수 있다.

• 한국항행학회논문지
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• 제12권2호
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• pp.122-131
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• 2008

본 논문에서는 마이크로스트립 헤어핀 형태의 링 공진기를 이용하여 저위상 잡음을 개선한 소형화된 S 대역에 사용가능한 발진기를 설계 및 제작하였다. 기판은 고조파 특성이 우수한 유전율 ${\varepsilon}_r$=3.5 기판두께 h=20mil 금속두께 t=17um 손실 탄젠트 $tan{\delta}$=0.0025 인 TACONIC사의 RF-35를 사용하였다. 측정된 결과 발진 주파수는 2.45 GHz에서 출력전력은 20.9 dBm으로서 기존의 발진기에 비하여 상당히 높은 출력을 얻었고, 위상 잡음 특성은 100 kHz offset에서 -100.5 dBc/Hz 로서 기존의 발진기 성능과 비교하면 우수한 특성이 있음을 확인할 수 있었고, 고조파 억압 특성은 32 dBc 이상으로서 우수한 특성을 갖는 발진기임을 보여주었다. 본 논문에서 제안된 발진기의 형태를 이용하여 RFIC, MIC, MMIC 형태로 제작한다면 발진기를 소형화할 수 있을 것이며, 이 제작된 발진기는 S-밴드의 주파수원으로 이용 가능할 수 있을 것으로 사료된다.

• 전기학회논문지
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• 제65권5호
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• pp.819-824
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• 2016

The accelerated thermal aging of CSPE (chlorosulfonated polyethylene) was carried out for 33.64 and 67.27 days at 110[$^{\circ}C$], equivalent to 40 and 80 years of aging at 50[$^{\circ}C$], respectively. These samples were referred to as CSPE-0y, CSPE-40y and CSPE-80y, respectively. As the accelerated thermally aged years of the CSPE increase, the insulation resistance[$\Omega$] at 20[Hz], 500[Hz], and 2[KHz], and the percent elongation [%EL] of the CSPE decrease. However, the dissipation factor($tan{\delta}$) at 20[Hz], 500[Hz], and 2[KHz], the apparent density[$g/cm^3$], the glass transition temperature and the melting temperature of the CSPE were increased. The period of time that the voltage has to be applied until electric breakdown of the CSPE-0y is longer than that of the CSPE-40y, and the CSPE-80y, but the dielectric strength of the CSPE-80y is lower than that of the CSPE-0y and the CSPE-40y. The differential temperatures after the AC and DC voltages are applied to CSPE-0y, CSPE-40y and CSPE-80y are 0.026~0.028[$^{\circ}C$], 0.030~0.042[$^{\circ}C$], 0.018~0.045[$^{\circ}C$], respectively. The variations of temperature for the AC voltage are higher than those for the DC voltage when an AC voltage is applied to CSPE-0y, CSPE-40y and CSPE-80y. It is found that the dielectric loss owing to the dissipation factor[$tan{\delta}$] is related to the electric dipole conduction current. It is ascertained that the ionic (electron or hole) leakage current is increased by the separation of the branch chain of CSPE polymer from the main chain of the polyethylene as a result of thermal stress due to accelerated thermal aging as well as by conducting ions such as $Na^+$, $Cl^-$, $Mg^{2+}$, $SO_4^{2-}$, $Ca^{2+}$ and $K^+$ after seawater soaking.