• Elastomers and Composites
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• 제18권2호
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• pp.51-59
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• 1983

고분자물질의 유전특성은 고분자의 분자구조를 연구하는데 대단히 중요하다. 황가황에 의한 천연고무의 유전흡수특성을 25[$^{\circ}C$]의 온도에서 주파수영역 10[KHz]부터 32[KHz] 사이에서 연구하였는데, 결과로서 황 4phr 이하의 가황 천연고무에서는 계면분극과 쌍극자 분극에 의한 두종류의 유전손실이 나타났고 황 7phr 이상의 가황 천연고무에서는 쌍극자분극에 의한 손실만이 존재함을 확인하였다. 더욱이 황의 증가로 저주파수쪽으로 이동되는 유전 손실스펙트럼의 최대치 $tan{\delta}$는 황에 의해 변화되며 체적고유저항은 황의 첨가와는 무관하였고 그 크기는 $10^{7}{\sim}10^{11}[{\Omega}{\cdot}cm}]$이였다.

• E2M - 전기 전자와 첨단 소재
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• 제1권1호
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• pp.54-61
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• 1988

This paper was a study on dielectric phenomena of the specimen, Polypropylene films which were annealled in air and quenched in liquid nitrogen after aging for 5[hr] in water of 100[.deg.C]. The specimen was measured in temperature range of 15-120[.deg.C] and in frequency range of 30-1x 10$^{6}$ [HZ]. As the results of the study, it was confirmed that the tacticity of specimen was isotactic structure, and the degree of cryatallinity of the specimens calculated by means of Natta's method from XRD (X-ray Diffraction) spectrum was 55[%]. And for dielectric relaxation, .betha. peak-the tan .delta. (spectrum around 20[.deg.C])-attributed due to amorphous regions, and .alpha. peak - the tan .delta. spectrum around 90[.deg.C]-due to crystalline regions. It was identified that the degree of crystallinity of the specimen quenched in the liquid nitrogen was increased to 55-65[%], and that of the specimen annealled in the air was decreased to 55-50[%]. And activation energy from dielectric loss spectra was obtained 34.5[kcal/mole] for .alpha. peak and 80.5[kcal/mole] for .betha. peak, respectively.

• 한국안전학회지
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• 제18권4호
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• pp.64-70
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• 2003

The thermal properties of chloroprene rubber (CR) with $^{60}Co\;{\gamma}$-ray irradiation has been investigated. The prepared CR was irradiated up to 1000kGy radiation dose by $^{60}Co\;{\gamma}$-ray and the radiation degradation of CR was investigated by thermogravimetric analysis and differential acanning calorimetry. Dynamic mechanical properties measurement and FT-IR observation are carried out as well. From these analyses results, the glass transition temperature($T_g$), decomposition onset temperature(DOT), oxidative induction time(OIT), the peak temperature of loss modulus and mechanical tan ${\delta}$ values were compared for the radiation degradation level of CR. The tendency between $T_g$ and peak temperature of loss modulus and mechanical tan ${\delta}$ agreed well with radiation doses. Decomposition temperature, OIT and DOT showed the same tendencies as increasing radiation doses. It was verified that these analyses are available to estimate the degradation level of CR.

• 한국조명전기설비학회지:조명전기설비
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• 제11권2호
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• pp.110-118
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• 1997

본 논문은 DSP를 이용한 주상변압기 유전정접($tan\;delta$) 활선 측정기법을 제안하였다. 변압기 내부에 콘덴서를 삽입한 후 센서에 전압을 인가하고, 인가된 전압과 콘덴서에 흐르는 전류를 측정하여 본 논문에서 제안한 상호 상관 함수 기법을 이용하여 유전정접을 구하였다. 측정의 성능 향상을 위해 TMS320C31 DSP 보드를 사용하였으며 상호 상관 함수 기법을 사용하였다. 또한 노이즈 영향을 검토하기 위해 컴퓨터 시뮬레이션을 수행하였다. 본 연구의 검증을 위해 본 논문에서 구현한 측정장치와 Schering bridge을 사용하여 비고 실험을 하였다. 실험 결과 주상 변압기 절연진단에 충분히 활용할 수 있음을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.60-63
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• 1997

Dieletric ailed piezoelectric properties of Pb[$Zr_{0.45}$/ $Ti_{0.5-x}$/L $u_{x}$ (M $n_{1}$3//S $b_{2}$3)$_{0.05}$] $O_3$(0$\leq$x $\leq$0.03) were investigated. The partial substitution of $Ti^{4+}$ by a L $u^{3+}$ permitted improvement of the piezoelectric constant( $d_{33}$ ), electromechanical coupling factor ( $k_{p}$ ) and dielectric constant($\varepsilon$$_{33}$ /Sup T/). The dielectric loss(tan $\delta$ ) increased and mechanical quality factor(Qm) decreased with an increase of x were observed. A new piezoelectric material for actuator application was developed at x=0.02 with $d_{33}$ =370$\times$10$^{-2}$ /C/N, $k_{p}$ =58.5%, $\varepsilon$$_{33}$ $^{T}$ =1321, $Q_{m}$ =714 and tan $\delta$ =0.98%.%..%.%.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.462-463
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• 1996

This study describes the dissipation factor measuring techniques of insulating oil on the operating, transformer by using digital signal processing. After applying voltage to the sensor which is installed in a transformer, acquiring source voltage and current of sensor and using cross-correlation techniques, we can check the dissipation factor of insulating oil. To improve measuring accuracy and the speed of process, we use hardware such as TMS320C31 DSP board and analog filter and software such as fast cross-correlation techniques, rectangular window, and digital filtering techniques. We simulated the measuring accuracy and the degree of the noise effect of this new measuring techniques by computer simulation, and compared the simplified measuring devices with Schering Bridge on degraded insulating oil. The result showed that this measuring technique can be used as diagnostic method on the pole transformers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.270-272
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• 1996

This paper describes the dissipation factor measuring techniques of insulating oil on operating pole transformer by using digital signal processor. After applying voltage to the electrodes which is installed in a transformer, acquiring source voltage and current of electrodes and using cross-correlation techniques, we can check the dissipation factor of insulating oil. To improve measuring accuracy and the speed of process, we use hardware such as TMS320C31 DSP board and software such as cross-correlation techniques and rectangular window techniques. We simulated the measuring accuracy and the degree of the noise effect of this new measuring techniques by using computer simulation, and compared the simplified measuring devices with schering bridge on degraded insulating oil. The result showed that this measuring technique can be used as diagnostic method on the pole transformers.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2003년도 춘계공동학술대회논문집
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• pp.97-101
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• 2003

우수한 휴대폰용 전파흡수체를 개발하기 위해 실리콘을 지지재로 한 Mn-Zn 페라이트를 개발하여 전파흡수능을 조사하였다. 본 연구에서는 시편의 제작온도가 전파흡수능에 미치는 영향을 연구하였으며 온도가 증가함에 따라 tan $\delta$ > 1을 나타내는 주파수가 저주파로 이동하는 경향을 나타내었고 이로 인해 70 $^{\circ}C$에서 제작한 1 mm 두께의 전파흡수체가 휴대전화의 중심사용 주파수인 1.8 GHz 부근에서 3.4 ㏈인 우수한 흡수능을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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• pp.74-75
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• 2006

We have investigated dielectric properties depending on temperature in organic light-emitting diodes using 8-hydroxyquinoline aluminum ($Alq_3$) as an electron transport and emissive material. We analyzed the dielectric properties of organic light-emitting diodes using characteristics of impedance. he Impedance characteristics was measured complex impedance Z and phase $\theta$ in the temperature range of 10 K to 300 K. We obtained complex electrical conductivity, dielectric constant and loss tangent ($tan{\delta}$) of the device at room temperature. From these analyses, we are able to interpret a conduction mechanism and dielectric properties contributed by an interfacial and orientational polarization.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1321-1328
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• 2005

The characteristics of the diesel spray have affected certain aspects of engine performance, such as the power, fuel consumption, and emissions. Therefore, this study was performed to investigate the effects of various injection parameters. In order to obtain the effect of injection parameters on diesel spray characteristics, the experiment is performed by using a high temperature and pressure chamber. The behaviors of the spray are visualized by using a high speed video camera, spray angle, penetration, and various other things. The results of the experiment are summarized as follows. (1) The correlation of the spray penetration can be expressed as follows. $$0< t $$t_{b} (2) The correlation of the spray angle can be expressed as follows $$T_a=293K\;tan({\theta}/2)=0.59({\rho}a/{\rho}f)^{0.437}$$ $$T_a=473K\;tan({\theta}/2)=0.588({\rho}a/{\rho}f)^{0.404}$$ (3) The measured macro characteristics that include the spray tip penetration and spray angle corresponded with the established correlations.