• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.1
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• pp.87-99
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• 1998

We have studied the effects of red ginseng root extract on the derease of MMS-induced gemotoxicity in cultured NIH3T3 cells. The increase in survival and the recovery from DNA synthesis inhibition in MMS-treated cells as a function of normal medium incubation time was potentiated, at a rate higher than those in UV-irradiated cells, by the presence of the ginseng extract. The extract also increased the MMS-induced excision repair as determined by unscheduled DNA synthesis. The amount of MMS-induced DNA single strand breads that are accumulated by polymerase inhibitors was increased, but as a rate lower rate than in UV-induced strand break, by the presence of the extract. These results suggest that the red ginseng extract increase MMS-induced repair and could be used as a reagent for protectiong alkylating agent-induced genotoxicity and cytotoxicity.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.2
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• pp.51-56
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• 1993

In this paper the affect an inorganic filler and a filling up water absorption in epoxy composite material was represented. The results are summarized as follows; 1. In the case of Sample 1, Sample 2 and a fillng up water absorption, the frequency depenence of ${\varepsilon}_\tau$ shows the straight characteristic under $140^{\circ}C$. 2. Between lOOHz and 3kHz, the frequency dependency of $tan{\delta}$ is dominated by the loss of a dipole relaxation than the conductive loss for movement of a career. The effect of water absorption, is increased as the frequency is decreased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.221-228
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• 1998

In this study, the $\beta$-Polyvinylidene fluoride(PVDF) thin films were fabricated by physical vapor deposition method. Also, the properties of dielectric relaxation were studied to understand carrier's behavior of PVDF thin films, to be regarded as the excellent piezo and pyroelectricity. In the process of vapor deposition, the $\beta$-PVDF thin films have been fabricated under the condition of the substrate temperature at 3$0^{\circ}C$, the applied electric field at 142.8kV/cm and the pressure at 2.0${\times}10^{-5}$torr. The dielectric properties of PVDF have been studied in the frequency range 10Hz to 1MHz at temperature from 30 to $100^{\circ}C$. The relative dielectric constant of $\alpha$ and $\beta$-PVDF were 6.8 and 9.8, respectively, under a frequency of 1kHz. Such a phenomenon was caused by the decrease in intermolecular forces originated by the phase-transition from the TGTG' molecular conformation to the TT planar zig-zag conformation. And the relative dielectric constant is increased as a measuring temperature increases, because of the reduction of relaxation time caused by the decrease of intermolecular force.

• Electrical & Electronic Materials
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• v.7 no.3
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• pp.187-199
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• 1994

In order to find an effect of structural changes due to variation of addition ratio of anhydride hardener and postcuring herat-treatments upon electrical properties of epoxy composites, the dielectric properties over a frequency range from 30[Hz] to l[MHz] were investigated in the temperature range of 20-180[.deg. C]. From the dielectric properties, the a peaks related with glass-transition phenomena of epoxy network appeared near 130[.deg. C], the conduction loss in high temperature region above 150[.deg. C] due to thermal dissociation of hardener started off with the low frequency side and the .betha. peak concerned with contribution of movable unreacted terminal epoxy groups and curing agents in the glass states concurred with the high-frequency side below 20[.deg. C]. And an effect of an hydride hardener upon structural changes and of postcuring heat treatments upon structural stability in epoxy composites would be explained through the estimation of the distribution of relaxation times and the activation energy for a .alpha. peak according to the WLF equations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.35-43
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• 1999

Microstructures and dielectric properties of (Sr$\_$1-x/Ca$\_$x/) TiO$_3$-0.006Nb$_2$O$\_$5/ (0.05$\leq$x$\leq$0.2) boundary layer ceramics were investigated. The samples fired in a reducing atmosphere(N$_2$) were painted on the surface with CuO paste for the subsequent grain boundary diffusion, and then annealed at 1100$^{\circ}C$ for 2 hrs. The metal oxide of CuO infiltrated by thermal diffusion from surface of sample presents continuously in not grain but only grain boundary, and makes up thin boundary phase. The SEM photo, and EDAX revealed that CuO was penetrated rapidly into the bulk along the grain boundaries during the annealing. The average grain sizes is continuously increased as the content of substitutional Ca is increased from 5[mol%] to 15[mol%], but the average grain size of the sample with content of 20[mol%] Ca is slightly decreased. In the samples with content of 10∼15[mol%] Ca, excellent dielectric properties were obtained as follows; dielectric constant <25000, dielectric loss <0.3[%], and capacitance change rate as a function of temperature <${\pm}$10[%], respectively. All samples in this study exhibited dielectric relaxation with frequency as a functior of the temperature.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.95-95
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• 2019

상추(Lactuca sativa L.)는 대표적인 쌈 및 샐러드 채소로 우리나라 기준(2016년) 3,387 ha의 면적에서 86,128톤을 생산하여 엽채류 중 배추, 양배추 다음으로 많이 생산되는 작물이다. 안토시아닌(Anthocyanins)은 열매, 꽃, 줄기, 잎 등 식물계에 널리 분포되어 있는 페놀 화합물 중 하나로 적색, 자색 등의 색을 나타내는 수용성 flavonoid계 색소이다. BSLs (Bitter sesquiterpene lactones)는 항암, 항균, 해열과 염증완화에 효과가 있는 것으로 알려져 있다. 본 연구는 농촌진흥청 농업유전자원센터에서 보유 중인 상추 66자원의 형태학적 특성 및 액체크로마토그래피(HPLC, UPLC)를 이용한 안토시아닌과 BSLs성분을 분석하여 함량이 높은 자원을 선발하고자 한다. 상추시료 0.05 g을 $MeOH/H_2O/AcAc$로 추출 한 후, UPLC를 사용하여 안토시아닌 함량을 분석하였으며, 상추시료 0.25 g을 100% MeOH로 추출 한 후 HPLC를 사용하여 BSLs 함량을 분석하였다. 연구 결과, 상추 유전자원의 안토시아닌 함량 범위는 0 mg/100 g에서 371.94 mg/100 g이고, BSLs성분 함량 범위는 $60.28{\mu}g/g\;DW$에서 $2821.92{\mu}g/g\;DW$ 이었다. 상추 66자원 중 안토시아닌함량이 200 mg/100 g이상인 자원은 IT217012, IT218395, IT231524, IT231525, IT260852이며, BSLs 함량이 $1700{\mu}g/g\;DW$이상인 자원은 IT231524, IT231525, IT231527, IT264971, IT271118이다. 두 성분의 함량이 모두 높은 자원 IT231524와 IT231525 이었다. 이 두자원의 형태적 특성은 초형이 잎상추로 잎이 넓은 타원형에 가장자리 결각이 강한 자주색이다. 따라서 본 연구는 다양한 상추 유전자원의 형태학적 특성 및 BSLs, 안토시아닌 성분이 높은 자원을 선발하여 육종소재로 활용하고자 한다.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.215-218
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• 1994

Dielectric properties of $(Sr_{l-x}{\cdot}Ca_x)_mTiO_3+0.006Nb_2O_5$($0.05{\leq}x{\leq}0.2$, 0.996$N_2$) were painted on the surface with CuO paste, and then annealed at $1100^{\circ}C$ for 2hr. Grain size increased with increasing substitutional contents of Ca up to 15[mol%], but decreased with further substitution. In the specimens with $10{\sim}15[mol%]$ of Ca and m=1, excellent dielectric properties were obtained as follows; dielectric constant <25000, dielectric loss($tan{\delta}[%]$) <0.3[%] and capacitance change rate with temperature <${\pm}10[%]$, respectively. All the specimens in this study exhibited dielectric relaxation with frequency as a function of the temperature. The dispersive frequency was over $10^6[Hz]$.

• Electrical & Electronic Materials
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• v.10 no.3
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• pp.239-246
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• 1997

The ZnO is stabilize dielectric constant over a broad temperature range because its addition makes the relaxation time short. In this study, the composite oxide material (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_{3}$ was mixed by ZnO additive material and the dielectric polarization characteristics was studied. The relative density was over 90[%] at all specimen in the structural characteristics. Among of the specimen, the relative density of (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_{3}$ with ZnO (0.4mol) has a 95[%]. The grain size of composite oxide material with an increasing ZnO increased and it was 1.0[.mu.m]-1.22[.mu.m]. In the electrical characteristics, the charge and discharge current was increased by ZnO addition. The dielectric relaxation time was increased by space charge polarization at above 110[.deg. C] and the dielectric relaxation time was fixed by space charge polarization of para-dielectric layer at below 110[.deg. C]. The dielectric relaxation time was maximum when the grain size was small. The dielectric relaxation time is decreased with an additive material ZnO and interface polarization, existing void at the grain and grain boundary. The remnant polarization is increased and the coercive electric field is decreased by ZnO.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.583-589
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• 2011

The dielectric breakdown of bone-like materials subject to purely electric fields is investigated. In general, these materials consist of some layers with stronger dielectric strength and others with weaker dielectric strength in a parallel staggered pattern. The growth of the conductive channel is impeded during penetration of the weaker layer in the bone-like material because the electric-field concentration is relieved. The electric-field distribution around the head of the tubular channel is obtained from finite element analysis. The dielectric strength of the bone-like material is evaluated using the J integral, and some parameters affecting the dielectric strength are determined. It is shown that the J-integral values are reduced with an increase in the breakdown area in the weaker layer. It is also found that the ratio of the permittivity of the weaker layer to that of the stronger layer can strongly affect the dielectric breakdown.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1063-1064
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• 2011

GIS에 이상전압이 흐를 때, 이를 계측하여 전력기기의 손상 및 고장을 미연에 방지하기 위해 SF6 계기용 변압기를 사용한다. 이러한 계기용 변압기는 절연 파괴가 일어나지 않도록 설계하여야 한다. 특히, 절연은 권선 부분이 중요한 구성 요소로, 권선간의 전기적 절연특성해석을 통하여 전계강도를 완화할 수 있는 절연 설계를 수행하여야 한다. SF6 계기용 변압기는 SF6가스의 유전율이 절연물에 비해 적기때문에 가스에서의 전계 집중 현상이 생기게 된다. 본 논문에서는 SF6 계기용 변압기의 권선간 절연특성해석을 수행하였다. 1차 권선과 2차 권선의 형상을 모델링하고 유한요소법을 사용하여 축대칭 2차원 전계해석을 수행한다. 이 때 발생하는 전계강도를 예측하고 최대전계강도가 발생하는 영역을 찾는다.