• Proceedings of the Korean Society of Crop Science Conference
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• 1994.10a
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• pp.22-23
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• 1994

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.69-76
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• 1995

Cold acclimation involves changes in gene expression. BN28 and BN115 are two genes which are regulated by cold temperature and assumed having roles in cold acclimation. The objectives of this experiment was to explore the expression of BN28 and BN115 under field conditions. Six winter cultivars were planted at three different dates during the fall. The expression of the genes was determined by northern blot analysis of total RNA taken from leaves 15 to 30 day-intervals after planting. The expression of the two genes was detected within 15 days after planting well before onset of freezing tolerance in plants. This suggestes either their expression was a prerequisite of the freezing tolerance or their expression was regulated by other environmental factors as well as temperature. Two genes showed a different expression pattern suggesting they had a different regulatory system. Although timecourse increase in expression of the cold-regulated genes was matched with increase in freezing tolerance, the difference of expression in cultivar level at specific times of measurement was not correlated with freezing tolerance at the moment.

• Korean Journal of Plant Resources
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• v.28 no.6
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• pp.675-681
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• 2015

β amyloid protein (Aβ) plays a critical role in the pathogenesis of Alzheimer's disease (AD) and possibly in Aβ-induced mitochondrial dysfunction and oxidative stress. Aβ can directly cause reactive oxygen species (ROS) production. Overproduction of ROS is considered to be involved in the pathogenesis of neurodegeneration of AD. Here, we investigated 9 kinds of ramie (Boehmeria nivea, (L.) Gaud., BN; hereafter denoted as BN) for their protective action against oxidative stress in a cellular system using C6 glial cells. We observed loss of cell viability and high levels of ROS generation after treatment with hydrogen peroxide (H₂O₂) and Aβ_25-35. However, treatments with BN extracts led to an increase in cell viability and decrease in ROS production induced by H2O2 and Aβ25-35. In particular, the extracts of BN-01 (seobang variety from Seocheon) and BN-09 (local variety from Yeonggwang) showed excellent anti-oxidative properties. This indicates that BN extracts could prevent neurodegeneration by reducing oxidative stress in cells.

• BMB Reports
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• v.42 no.1
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• pp.28-34
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• 2009

To understand the molecular mechanism underlying proline accumulation in Brassica napus, cDNAs encoding ${\Delta}^1$-pyrroline-5-carboxylate synthetase (BnP5CS), ornithine $\delta$-aminotransferase (BnOAT) and proline dehydrogenase (BnPDH) were isolated and characterized. Southern blot analysis of BnP5CSs in B. napus and its diploid ancestors suggested a gene loss may have occurred during evolution. The expression of BnP5CS1 and BnP5CS2 was induced, while the expression of BnPDH was inhibited under salt stress, ABA treatment and dehydration, prior to proline accumulation. The upregulation of BnOAT expression was only detected during prolonged severe osmotic stress. Our results indicate that stress-induced proline accumulation in B. napus results from the reciprocal action of activated biosynthesis and inhibited proline degradation. Whether the ornithine pathway is activated depends on the severity of stress. During development, proline content was high in reproductive organs and was accompanied by markedly high expression of BnP5CS and BnPDH, suggesting possible roles of proline during flower development.

• Korean Journal of Breeding Science
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• v.51 no.4
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• pp.395-403
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• 2019

Rice blast caused by the fungus Magnaporthe grisea (anamorphic: Pyricularia oryzae) is an important disease in rice and development of resistant varieties to blast is one of the most important goals in rice breeding programs. A japonica rice variety, Palgong, has shown resistance to the Korean blast pathogen since it was developed in 1996. Nine blast resistance quantitative trait loci (QTLs) in Palgong alleles were identified on chromosomes 2, 4, 7, and 11. Four QTLs of qBn2.3, qBn4.2, qBn11.1, and qBn11.2 explained 28-56.7% of total phenotypic variation, while five QTLs of qBn2.2, qBn2.4, qBn4.1, qBn7.1, and qBn7.2 explained 9.7-18.8%. In a previous study, one to four resistance genes were located on the loci qBn2.2, qBn2.3, qBn4.2, qBn11.1, and qBn11.2, however, resistance genes were not located on the loci qBn2.4, qBn4.1, and qBn7.1. A major QTL, qBn11.2, explaining 56.7% of total phenotypic variation was related to the durable resistance of Palgong. Additionally, rice stripe virus resistance of Palgong was assumed to be based on the Stvb-i gene, which is located on a major QTL qBn11.2.

• Composites Research
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• v.28 no.5
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• pp.270-276
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• 2015

Polyvinylidene fluoride (PVDF)-based nanocomposites are fabricated by incorporation of boron nitride (BN) nanosheets with anisotropic orientation for a potential high thermal conducting ferroelectric materials. The PVDF is dissolved in dimethylformamide (DMF) and homogeneously mixed with exfoliated BN nanosheets, which is then cast into a polyimide film under application of high magnetic fields (0.45~10 T), where the direction of the filler alignment was controlled. The BN nanosheets are exfoliated by a mixed way of solvothermal method and ultrasonication prior to incorporation into the PVDF-based polymer suspension. X-ray diffraction, scanning electron microscope and thermal diffusivity are measured for the characterization of the polymer nanocomposites. Analysis shows that BN nanosheets are exfoliated into the fewer layers, whose basal planes are oriented either perpendicular or parallel to the composite surfaces without necessitating the surface modification induced by high magnetic fields. Moreover, the nanocomposites show a dramatic thermal diffusivity enhancement of 1056% by BN nanosheets with perpendicular orientation in comparison with the pristine PVDF at 10 vol % of BN, which relies on the degree of filler orientation. The mechanism for the magnetic field-induced orientation of BN and enhancement of thermal property of PVDF-based composites by the BN assembly are elucidated.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.215-217
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• 2007

철계 피삭재 가공 시 적용되는 cBN(cubic Boron-Nitride)의 경우 열적/구조적 안정성으로 인해 융착 시 계면에서 화학적 결합이 어려워, 지립이 단일층으로 형성되어야 하는 융착 공구의 경우 적용되질 못하고 있다. 이러한 문제를 해결하기 위해 세라믹과의 젖음성이 우수한 Ti 성분이 포함된 67Ag+28Cu+5Ti(wt.%) 조성의 합금분말을 이용하여 cBN을 접합을 하였으며, 이때 융착조건은 진공 분위기($6{\times}10^{-6}$Torr), $900^{\circ}C$ 온도에서 5분간 유지하여 융착을 실시하였다. 본 연구의 주목적은 Ti 합금화 된 Ag계 합금분말 및 cBN의 융착 계면에서의 융착 계면거동해석을 통한 건전한 접합공정을 찾는데 있다. 이에 온도 $900^{\circ}C$, 유지시간 5분에서 건전한 융착층을 형성함을 알 수 있었다. 또한 결합력 측정기를 이용하여 결합력을 측정한 결과 diamond와 융착하였을 때가 123N, cBN을 융착하였을 때 107N으로써, cBN 융착이 diamond 융착의 87%정도의 결합력을 보임을 알 수 있었다. 한편 cBN과 Ag-Cu-Ti계 브레이징 필러의 계면에서의 미세조직 및 화학반응의 메커니즘은 SEM, EDS를 이용하여 분석하였다.

• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.637-639
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• 2010

Hexagonal boron nitride (BN) films were prepared. The process involved, spraying BN powder-dispersed $H_3BO_4-BCl_3$-ethyl alcohol solution on quartz plates, and the drying off quartz plates before, and annealing at $1070^{\circ}C$ in a nitrogen atmosphere. The optical energy band gap of the BN films was 5.28 eV. Photoluminescence peaks with energies of 3.44, 3.16, 2.97, and 2.35 eV at 10 K were observed and analyzed. Accordingly, these have resulted from donor-acceptor pair recombinations.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.28-29
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• 1998

• Composites Research
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• v.34 no.1
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• pp.63-69
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• 2021

In order to develop an integrated heat dissipating material and gas barrier film for electronics, new polymer was designed and synthesized for preparing composites containing hexagonal boron nitride (hBN) filler. Depending on the size and content of the hBN filler, both thermal conductivity and oxygen transmission rate can be adjusted. The composite achieved a high thermal conductivity of 28.0 W·m-1·K-1 at most and the oxygen transmission rate was decreased by 62% compared to that of the filler free matrix. Effective filler aspect ratios could be estimated by comparing thermal conductivity and oxygen transmission rate with values predicted by theoretical models. Discrepancy on the aspect ratios extracted from thermal conductivity and oxygen transmission rate comparisons was also discussed.