• Elastomers and Composites
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• 제46권4호
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• pp.324-328
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• 2011

신발 밑창용 CIIR에 BR, SBR 및 NBR을 다양한 조성으로 혼합하여 블렌드물의 내마모성과 마찰계수에 미치는 영향을 고찰하였다. CIIR이 BR에 블렌딩됨에 따라 CIIR이 BR의 결정 형성을 방해하며, 이것이 BR/CIIR 블렌드물의 내마모성을 급격히 감소하는 요인 중의 하나로 작용하는 것으로 이해된다. BR/CIIR 블렌드물에서 BR의 함량이 증가함에 따라 $tan{\delta}$ 피크 면적이 저하하였으며, 블렌드물의 마찰계수도 유사하게 저하하는 경향을 나타내었다. CIIR에 BR을 첨가함에 따라 블렌드물의 응력완화율 및 반발탄성이 감소하였으며, 블렌드물의 반발탄성에 영향을 미치는 것으로 추정된다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.19.1-19.1
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• 2011

Effects of particle size, crystal structures and multilayer structures of $ATiO_3$, $ATa_2O_6$, $ANb_2O_6$, $AWO_4$, and $AMoO_4$ (A=Ni, Mg, Zn, Co) ceramic fillers on the dielectric properties of polystyrene (PS), polypropylene (PP) and polytetrafluoroethylene (PTFE) polymer matrices were investigated at microwave frequencies. The microwave dielectric properties of $ATiO_3$ (ilmenite), $ATa_2O_6$ (tri-rutile), $ANb_2O_6$ (columbite), AWO4 (wolframite), and AMoO4 (wolframite) ceramics were largely dependent on the structural characteristics of oxygen octahedra. The dielectric constant (K) of the composites was increased with the ceramic content. However, the dielectric loss (tan ${\delta}$) of the composites was affected by the type of ceramics and the crystallinity of polymers. For the composites with same amount of ceramics, the K was decreased and the tan ${\delta}$ was increased with the particle size of ceramics. Also, the dielectric properties of the composites were dependent on the multilayer structures with different arrangements. Several theoretical models have been employed to predict the effective dielectric properties of the composites. The frequency dependence of dielectric properties and the temperature coefficient of resonant frequency (TCF) of the composites were also discussed.

• 전력전자학회논문지
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• 제8권3호
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• pp.247-252
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• 2003

전동기 절연열화와 파괴는 전동기에 가해지는 스트레스에 영향을 받는다. 즉 절연물의 수명은 주어지는 스트레스의 심한 정도에 따라서 좌우된다. 전동차용 견인전동기에서도 과도서지에 의한 전기적인 열화를 검토하는 것은 매우 중요한 요소이다. 본 논문에서는 인버터에서 발생되는 과도서지에 의한 고정자 코일의 절연특성을 고찰해 보았다. 전동기의 절연상태, 열화진전도, 열화발생 범위 등을 측정하는 유용한 비파괴시험 방법에는 여러 가지가 이용되고 있다. 누설전류, 유전손실(tan$\delta$), 정전용량, 성극지수(PI), 부분방전 등의 방법들을 통하여 고정자 코일의 절연상태를 분석하였다. 이러한 진단 방법들은 전동차의 견인전동기에 대한 열화상태와 수명예측에 유용한 방법이 될 것으로 여겨진다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.297-300
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• 2004

In this paper, we investigated insulation property of epoxy resin which includes elastomers to improve mechanical property, as varied to additive elastomer contents and to moisture absorption. There are four samples with 5[phr], 10[phr], 15[phr] and 20[phr]. we experimented to acquire insulation property(absorption rate, dissolution rate, apparent rate) and electrical property(perittivity, $tan\delta$, BDV) during respectively the time such as 6[h], 12[h], 18[h], 24[h] for moisture absorption. According to the experimental results, it is appeared that when the additive elastomer contents are increasing or when specimens remain more moisture, absorption rate, dissolution rate, permittivity and $tan\delta$ are slightly increasing but apparent rate and BDV(break-Down Voltage) strength are decreasing in particular, elastomer content [20]phr appeared remarkedly the more increase or decrease than others.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.293-294
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• 2005

We have investigated dielectric properties depending on frequency 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 impedance of characteristics. impedance characteristics was measured complex impedance Z and phase $\Theta$ in the frequency range of 40 Hz to $10^8$ Hz. 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.140-141
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• 2005

To measure elastic properties of semiconducting materials in power cable, we have investigated modulus of EVA/acetylene black composite showed by changing the content of acetylene black. The specimen was primarily kneaded in material samples of pellet form for 5 minutes on rollers ranging between 70[$^{\circ}C$] and 100[$^{\circ}C$]. Then this was produced as sheets after pressing for 20 minutes at 180[$^{\circ}C$] with a pressure of 200[kg/cm]. The contents of conductive acetylene black were 20, 30 and 40[wt%], respectively. The modulus experiment was measured by DMA 2980. The ranges of measurement temperature were from -50[$^{\circ}C$] to 100[$^{\circ}C$] and measurement frequency is 1[Hz]. The modulus of specimens was increased according to an increment of acetylene black content. And modulus was rapidly decreased at the glass transition temperature. The tan$\delta$ of specimens was decreased according to an increment of acetylene black content.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.136-137
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• 2005

To measure elastic properties of semiconducting materials in power cable, we have investigated modulus of EBA/carbon black composite showed by changing the content of carbon black. The specimen was primarily kneaded in material samples of pellet form for 5 minutes on rollers ranging between 70[$^{\circ}C$] and 100[$^{\circ}C$]. Then this was produced as sheets after pressing for 20 minutes at 180[$^{\circ}C$] with a pressure of 200[kg/cm]. The contents of conductive carbon black were 20, 30 and 40[wt%], respectively. The modulus experiment was measured by DMA 2980. The ranges of measurement temperature were from -50[$^{\circ}C$] to 100[$^{\circ}C$] and measurement frequency is 1 [Hz]. The modulus of specimens was increased according to an increment of carbon black content And modulus was rapidly decreased at the glass transition temperature. The tan$\delta$ of specimens was decreased according to an increment of carbon black content.

• 한국전자파학회논문지
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• 제13권3호
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• pp.301-307
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• 2002

본 논문에서는 종래 세라믹 칩 안테나의 단점인 협대역 특성을 개선하기 위해 헬리컬 구조를 갖는 적층형 세라믹 칩 안테나의 인덕턴스가 대역폭 향상에 미치는 영향을 3D 구조 시뮬레이션 결과에 의해 고찰하였다. 적층형 세라믹 칩 안테나를 고주파 구조 시뮬레이터인 HFSS에 의해 설계하였고, LTCC-MLC 공정 기술을 이용하여 유전 특성이 $\varepsilon$$_{r}$=7.8, tan $\delta$=0.0043인 유전체로 구현하였다. 또한, IMT-2000용 단말기에 적용 가능성을 보기 우하여 그 운용 주파수 (1,920~2,170 GHz)대에 설계된 안테나 제작하여, 주파수 응답 특성 및 복사 특성을 측정하였다.

• Preventive Nutrition and Food Science
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• 제13권3호
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• pp.245-248
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• 2008

The effects of native sweet potato starch (NSPS) and sweet potato starch modified by acetylation (MSPS) on dynamic rheological properties of surimi sols were investigated by small-deformation oscillatory measurements. Dynamic frequency sweeps of surimi sols at $10^{\circ}C$ showed that the addition of NSPS and MSPS resulted in a reduction of storage modulus (G') and loss modulus (G"). The tan $\delta$ values (ratio of G"/ G') of all samples were in the range of $0.15{\sim}0.54$ over a wide range of frequency, indicating that all surimi sols are more elastic than viscous. The characteristic G' thermograms of surimi sols during heating from 10 to $90^{\circ}C$ were influenced by the addition of starch. The tan $\delta$ values of all samples were maintained nearly constant above $45^{\circ}C$, showing that the G' is proportional to the G" irrespective of starch effects.

• Korean Chemical Engineering Research
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• 제46권1호
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• pp.76-81
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• 2008

아크릴계 점착제를 합성한 후 이관능성 혹은 육관능성 우레탄-아크릴레이트 올리고머를 혼합하여 자외선 경화형 점착제를 제조하였다. 올리고머 종류 및 함량을 변화시켜 그에 따른 접착력 변화와 재박리 특성을 조사하였다. 자외선 경화전에는 올리고머의 함량의 증가에 따라 박리력이 증가하였으나 자외선 경화 후에는 감소하는 경향을 보였다. 저장 탄성률(G')이 낮을수록 박리력은 증가하지만 점착제 내부의 상용성과 손실계수(tan ${\delta}$) 값에 따라 점착제의 박리정도와 접착력에 영향을 주는 것을 확인할 수 있었다.