• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.506-509
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• 2003

In this paper, the $\Phi$-q-n pattern and average discharge power of silicone rubber have investigated effect of inter impurities. It's changed impurities by silicone oil, water and copper. Applied voltage is AC 3, 4, 4.5, 5, 5.5[kV]. And data acquisition time is 10 second(600 cycles). These results suggest that partial discharge(PD) is shower negative polar than positive polar at 3[kV]. Positive polar's PD value increased with increase of applied voltage. The Conductivities expressed same $\Phi$-q-n pattern in positive polar and negative polar at phase region.

• 천문학회지
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• 제28권1호
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• pp.61-65
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• 1995

We discuss a model4-dimensional Friedmann cosmology which may have evolved from a model of 4+D dimensions which admits spontaneous compactification of D dimensions (or N-dimensional variants of the Brans-Dicke (BD) theory). The BD parameter appearing in dimensional reduction is negative $-1<\omega<0$ (for the N-dimensional variants of the BD theory, $-1.5{\leq}{\omega})$. We find that if there had been inflationary transtion to the standard big-bang model, the Universe can undergoe a polar-type expansion during when the gravitational coupling becomes negative. The unique feature is that for the negative w, the density parameter of the post-inflationary Universe falls in a range 0<0<1 even if the Universe is geometrically flat (k = 0).

• Journal of Astronomy and Space Sciences
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• 제37권1호
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• pp.69-75
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• 2020

We analyze the observations of temperature and ozone measured by the Microwave Limb Sounder (MLS) during the period of 2005-2016, to investigate the vertical structures of temperature and ozone in the stratosphere and mesosphere during stratospheric sudden warming (SSW). We compute the height profiles of the correlation coefficients between 55 height levels of MLS temperature anomalies and compare them with the results of Whole Atmosphere Community Climate Model simulations for three major SSWs. We also construct the temperature and ozone anomalies for the events to investigate the changes in the temperature and ozone distributions with height. There seems to always be a relatively weak but broad negative correlation between the temperature anomaly at 10 hPa and temperature anomalies over the entire mesosphere during the period before SSW events. However, this pattern gets stronger in the lower mesosphere but becomes a positive correlation in the upper mesosphere and lower thermosphere after the onset of SSW. We also found that the temperatures from the simulations show a similar trend to the observational results but with smaller variations and the transition height from negative to positive correlation in the mesosphere is much lower in the simulation than in the actual observations.

• Journal of Plant Biology
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• 제36권1호
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• pp.9-17
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• 1993

Seven dictyostelid cellular slime molds isolated from the forest soils of Mt. Halla were described and illustrated. Dictyostelium flavidum Hong et Chang and three unidentified Dictyostelium, HL-2, HL-3 and CJ-9 were compared and discussed. All the isolates were cultivated on low nutrient media, 0.1- L-P(pH6) with Escherichia coli at 20-22$^{\circ}C$. Seven unrecorded species were all polar granule (PG) negative. These were Dictyostelium crassicaule Hagiwara, D. sphaerocephalum (Oud.) Sacc. et March, D. macrocephalum Hagiwara, Yeh et Chien, D. capitatum Hagiwara, D. brefeldianum Hagiwara, D. aureum var. aureum Cavender, Worley and Raper, and D. giganteum Singh.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.157-162
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• 2007

Geophysical survey has been conducted on the continental margin off the South Shetland Islands aboard R/V Onnuri of KORDI in 1992/1993. About 800-line km of 96-channel reflection data have been acquired. On the seismic section, BSR with strong reflectivity and negative polarity has been found at 700 ms below the sea bottom. BSR is considered as the base of gas hydrates and AVO analysis was performed to study physical properties along BSR. True amplitude recovery and surface consistence amplitude were applied to seismic data and angle gathers were obtained. AVO gradient and AVO intercept are calculated on every CDP gather. Section of AVO intercept show strong reflectivity and negative polarity on BSRs and stronger continuity of BSR than stacked section. Cross plot of intercept-gradient indicates that the lower layer below BSR is filled with free gas.

• Ocean and Polar Research
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• 제24권3호
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• pp.301-311
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• 2002

We used diatom and porewater data of two piston cores from the central subbasin and one from the western subbasin in the Bransfield Strait in the northern Antarctic Peninsula to elucidate the depositional mechanism of the layered diatom ooze. The layered diatom ooze is characterized by an abundance of organic carbon, biogenic silica, sulfde sulfur, and lower porewater sulfate concentration. This lack of pore-water sulfate concentration in the diatom ooze interval may reflect development of reducing micro-environment in which bacterially mediated sulfate reduction occurred. The negative relationship between the total organic carbon and sulfate contents, however, indicates that sulfate reduction was partly taking place but does not control organic carbon preservation in this unit. Rather, well-preserved Chaetoceros resting spores in the layered diatom ooze indicate a rapid sedimentation of the diatom as a result of repetitive iceedge blooms on the Bransfield shelf during the cold period (around 2500 yrs BP) when the permanent seaice existed on the shelf, During this period, it is expected that the downslope-flowing cold and dense water was also formed on the Bransfield shelf as a result of sea ice formation, playing an important role for the formation of layered diatom ooze in the Bransfield subbasins.

• ALGAE
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• 제37권2호
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• pp.175-183
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• 2022

Polar microorganisms produce physiologically active substances to adapt to harsh environments, and these substances can be used as biomedical compounds. The green microalga Micractinium variabile KSF0031, which was isolated from Antarctica, produced phytol, a natural antimicrobial agent. Furthermore, several polyunsaturated fatty acids (PUFAs), including omega-3, exhibit antioxidant properties. Here statistical methods (Plackett-Burman design and Box-Behnken design) were used to optimize the culture medium of KSF0031 to improve biomass production, and K₂HPO₄, MgSO₄·7H ₂O, and ammonium ferric citrate green (AFCg) were selected as significant components of the culture medium. Changes in the concentration of K₂HPO₄ and MgSO₄·7H ₂O as positive factors and AFCg as a negative factor affected cell growth to a remarkable degree. The biomass production in a 100 L culture using the optimized medium for 24 d at 18℃ was improved by 37.5% compared to that obtained using the original BG-11 medium. The quantities of PUFAs and phytol obtained were 13 mg g^-1 dry cell weight (DCW) and 10.98 mg g^-1 DCW, which represent improved yields of 11.70% and 48.78%, respectively. The results of this study could contribute to an improved production of phytol and fatty acids from Antarctic microalgae in the biomedical industry.

• Asian Pacific Journal of Cancer Prevention
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• 제13권6호
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• pp.2729-2734
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• 2012

Despite clinical advances in anticancer therapy, there is still a need for novel anticancer metabolites, with higher efficacy and lesser side effects. Oroxylum indicum (L.) Vent. is a small tree of the Bignoniaceae family which is well known for its food and medicinal properties. In present study, the chemopreventive properties of O. indicum hot and cold non-polar extracts (petroleum ether and chloroform) were investigated with MDA-MB-231 (cancer cells) and WRL-68 (non-tumor cells) by XTT assay. All the extracts, and particularly the petroleum ether hot extract (PHO), exhibited significantly (P<0.05) higher cytotoxicity in MDA-MB-231 when compared to WRL-68 cells. PHO was then tested for apoptosis induction in estrogen receptor (ER)-negative (MDA-MB-231) and ER-positive (MCF-7) breast cancer cells by cellular DNA fragmentation ELISA, where it proved more efficient in the MDA-MB-231 cells. Further, when PHO was tested for anti-metastatic potential in a cell migration inhibition assay, it exhibited beneficial effects. Thus non-polar extracts of O. indicum (especially PHO) can effectively target ER-negative breast cancer cells to induce apoptosis, without harming normal cells by cancer-specific cytotoxicity. Hence, it could be considered as an extract with candidate precursors to possibly harness or alleviate ER-negative breast cancer progression even in advanced stages of malignancy.

• Ocean and Polar Research
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• 제33권3호
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• pp.281-290
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• 2011

This study examined the change in sea surface temperature (SST) around the Korean peninsula since industrialization at year 1880, and its possible causes using observation based data from the Hadley Center, the Goddard Institute of Space Studies, and National Climate Data Center. Since year 1880, There have been multi-decadal fluctuations with a gradual reduction from 1880 to around 1940, and from 1950-1980. There has then been a marked increase from 1940-1950, and from 1980 to the present. The ocean surface warming is larger during the boreal winter than summer, and greater in the south. The multi-decadal SST fluctuations around the Korean Peninsula are largely consistent with the negative phase of the Pacific Decadal Oscillation (PDO), which fluctuates with periods of about 20-50 years. Secondly, the El Ni$\tilde{n}$o-Southern Oscillation (ENSO), whose long period component moves along with the PDO, appears to influence the SST near the Korean Peninsula, especially in recent decades. Overall, the SST around the Korean Peninsula has warmed since year 1880 by about $1^{\circ}C$, which is about twice the global-mean ocean surface warming. This long-term warming is aligned with an increase in greenhouse gas concentration, as well as local factors such as the PDO.

• Journal of Astronomy and Space Sciences
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• 제27권3호
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• pp.205-212
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• 2010

To better understand the physical processes that maintain the high-latitude lower thermospheric dynamics, we have identified relative contributions of the momentum forcing and the heating to the high-latitude lower thermospheric winds depending on the interplanetary magnetic field (IMF) and altitude. For this study, we performed a term analysis of the potential vorticity equation for the high-latitude neutral wind field in the lower thermosphere during the southern summertime for different IMF conditions, with the aid of the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM). Difference potential vorticity forcing and heating terms, obtained by subtracting values with zero IMF from those with non-zero IMF, are influenced by the IMF conditions. The difference forcing is more significant for strong IMF $B_y$ condition than for strong IMF $B_z$ condition. For negative or positive $B_y$ conditions, the difference forcings in the polar cap are larger by a factor of about 2 than those in the auroral region. The difference heating is the most significant for negative IMF $B_z$ condition, and the difference heatings in the auroral region are larger by a factor of about 1.5 than those in the polar cap region. The magnitudes of the difference forcing and heating decrease rapidly with descending altitudes. It is confirmed that the contribution of the forcing to the high-latitude lower thermospheric dynamics is stronger than the contribution of the heating to it. Especially, it is obvious that the contribution of the forcing to the dynamics is much larger in the polar cap region than in the auroral region and at higher altitude than at lower altitude. It is evident that when $B_z$ is negative condition the contribution of the forcing is the lowest and the contribution of the heating is the highest among the different IMF conditions.