• Journal of Plant Biotechnology
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• 제7권3호
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• pp.203-209
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• 2005

This study was conducted to improve tocopherol (vitamin E) composition in soybean (Glycine max) by introducing a gamma-tocopherol methyl transferase (${\gamma}$-TMT) gene via Agrobacterium tumefaciens-mediated transformation. Immature cotyledon explants were cocultivated with Agrobacterium tumefaciens. Putative transgenic embryos were selected from immature cotyledons on MS medium supplemented with 40 mg/L 2,4-D containing 100 mg/L kanamycin, 500 mg/L carbenicillin and 250 mg/L cefotaxime. Plantlets were developed from somatic embryos, and then transferred to soil. Nineteen regenerated plantlets obtained on the selection medium from 1,460 cotyledons. However, only 9 plantlets were confirmed as transformed plants. Integration of the transgene into the soybean genomic DNA was confirmed by PCR and Southern blot analysis. HPLC analysis showed that the content of ${\alpha}$-tocopherol in transgenic soybean seeds (AT-1) was approximately 4-fold higher than that of non-transgenic plants. Conclusively, we obtained the transgenic soybean having increased ${\alpha}$-tocopherol content by the overexpression of ${\gamma}$-TMT transgene.

• Journal of Korean Neurosurgical Society
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• 제30권sup2호
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• pp.273-280
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• 2001

Objectives : The purpose of this study is to assess the long-term outcome and delayed complications of Gamma Knife radiosurgery for low grade glioma(LGG). Methods : Among 31 patients of LGG who had been treated by using Leksell Gamma Knife between March 1992 and December 1996, we could follow up more than 5 years(range 5-9 years) in 17 patients and evaluated their clinical feature, changes of tumor volume and post-radiosurgical complications. Results : During the mean follow-up period of 7.6 years, the tumor was decreased in 5 patients(29.4%), unchanged in 4(23.5%), increased in 4(23.5%) and recurred in 4(23.5%). The tumor control rate was 52.9%(9/17). We have experienced eighteen postradiosurgical complications in 10 patients(58.8%). Early complication was none and delayed complications included radiation necrosis with cyst in ten cases, bleeding in five, radiation-induced edema in one and malignant transformation in one. Two patients ultimately died as a result of tumor progression during the follow-up period. The mortality rate was 11.7%. Conclusion : Gamma Knife radiosurgery may be useful as an adjunctive therapy for small volume, deep-seated LGG. Although radiosurgery can effectively prevent growth of solid tumor, several delayed complications such as radiation necrosis, cyst formation, bleeding or malignant transformation can develop during the long-term followup period. Because of the possible slow growth rate of LGG and development of the delayed complications, the long-term efficacy of radiosurgery requires further analysis.

• 한국세라믹학회지
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• 제38권10호
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• pp.876-880
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• 2001

The supported and unsupported boehmite ($\gamma$-AlOOH) membranes were prepared using a boehmite sol. The supported membrane was consisted of a porcelain support, two intermediate $\alpha-{Al_2}{O_3}$ layers, and a top boehmite membrane. XRD patterns showed that the supported top membrane had a higher $\theta-$ to $\alpha-{Al_2}{O_3}$ transformation temperature compared to the unsupported membrane. This result was also confirmed from microstructural study of the membrane. The shift in the phase transformation temperature should be explained by difference of a stress generated in the supported top membrane due to interaction between the support layers and the top membrane.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.879-880
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• 2006

Effect of phase transformation and grain-size variation of hot-pressed cobalt on its dry sliding wear was investigated. The sliding wear test was carried out against glass (83% $SiO_2$) beads at 100N load using a pin-on-disk wear tester. Worn surfaces, cross sections, and wear debris were examined by an SEM. Phases of the specimen and wear debris were identified by an XRD. Thermal transformation of the cobalt from the hcp $\varepsilon$ phase to the $\gamma$ (fcc) phase during the wear was detected, which was deduced as the wear mechanism of the sintered cobalt.

• Kyungpook Mathematical Journal
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• 제58권1호
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• pp.19-35
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• 2018

Motivated mainly by certain interesting recent extensions of the generalized hypergeometric function [30] and the second Appell function [6], we introduce here the incomplete Lauricella functions ${\gamma}^{(n)}_A$ and ${\Gamma}^{(n)}_A$ of n variables. We then systematically investigate several properties of each of these incomplete Lauricella functions including, for example, their various integral representations, finite summation formulas, transformation and derivative formulas, and so on. We provide relevant connections of some of the special cases of the main results presented here with known identities. Several potential areas of application of the incomplete hypergeometric functions in one and more variables are also pointed out.

• Nuclear Engineering and Technology
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• 제33권2호
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• pp.184-191
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• 2001

The effects of ${\gamma}$-irradiation on the crosslinking of high density polyethylene (HDPE) was investigated for the purpose of obtaining a suitable formulation for heat shrinkable materials. In this study the HDPE specimens were prepared by blending with cross linking agents and pressed into a 0.2 mm sheet at 18$0^{\circ}C$. ${\gamma}$-irradiation was conducted at 40 to 100 kGy in nitrogen. The heat shrinkable property and thermal mechanical property of the HDPE sheets have been investigated. It was found that the degree of crosslinking of the irradiated HDPE samples were increased with irradiation dose. Compared with the HDPE containing triallylisocyanurate, the HDPE containing trimethylol propane triacrylate shows a slight increase in crosslinking density. The heat transformation and dimension change of HDPE decreased with increasing radiation dose. The heat shrinkage of the samples increased with increasing annealing temperatures. The thermal resistance of HDPE increased upon the crosslinking of HDPE.

• 한국결정성장학회지
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• 제24권2호
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• pp.59-64
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• 2014

전해질로 $Na_2SiO_3$을 사용하여 A1050 알루미늄 판재를 pulse 폭 $ 2000{\mu}sec$, impulse 420 V, 400 ${\mu}$sec의 unipolar pulse로 플라즈마 전해 산화 코팅(plasma electrolytic oxidation coating)을 하여 산화 피막을 2, 5, 15, 30분에 따라 형성시킨 다음 산화피막을 분석하였다. 표면에 형성된 산화물의 결정상은 ${\alpha}-alumina$와 ${\gamma}-Alumina$로서 시간에 따른 변화는 없었다. 반응 초반에는 ${\gamma}-Alumina$가 많이 생성되었지만 시간이 갈수록 ${\gamma}-Alumina$의 양에는 변화 없이 ${\alpha}-alumina$가 많이 생겨남을 알 수 있었다. 이런 결과는 micro plasma에 의해서 ${\gamma}-Alumina$가 우선 생성되고, 이후 계속되는 micro plasma의 열에 의해서 ${\alpha}-alumina$로의 전이가 일어나기 때문으로 판단된다.

• 열처리공학회지
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• 제13권2호
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• pp.85-90
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• 2000

The influence of transformation cycles (${\alpha}^{\prime}{\leftrightarrow}{\gamma}^{\prime}$) on the microstructure and mechanical properties of lath and lenticular martensites has been studied in Fe-Ni alloys. The width of lath in Fe-15%Ni alloy decreased with increasing the number of transformation cycles, while no appreciable change in dislocation density inside the lath was observed. In case of Fe-31%Ni alloy, a number of dislocations were additionally introduced into the martensite plate after the transformation cycling. Tensile strength and Vickers hardness of lath martensite decreased with the increase in number of transformation cycles, whereas those of lenticular martensite increased up to 1 cycle and then remained constant. Elongation of two alloys was deteriorated after 1 transformation cycling, corresponding to the tensile strength. But the decrement of elongation in Fe-31%Ni alloy was smaller than that in Fe-15%Ni alloy.

• 한국결정성장학회지
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• 제7권3호
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• pp.428-436
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• 1997

0.8$\mu$의 평균입자크기와 63$m^2/g$의 비표면적을 갖는 소질성이 뛰어난 hexacelsian분말이 so;ution-polymerization 방법에 의해 제조되어졌다. polymerization 경정을 통한 분말합성을 위하여 PVA 용액이 사용되었다. 소결후 치밀화된 hexacelsian은 $\alpha$,$\beta$,$\gamma$ 간의 상전이 거동을 보였고, 상대밀도 98.5% 의 치밀화ㄱ된 celsian 소결체가 $1600^{\circ}C$에서 72시간의 서냉공정을 거쳐hexacelsian의 상전이에 의하여 얻어졌다.

• 한국재료학회지
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• 제8권4호
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• pp.354-358
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• 1998

Inconel 719 선재의 경도에 미치는 냉간신선가공량과 시효시간의 영향을 경도측정과 전자현미경을 사용하여 조사하였다. 고용화처리된 재료의 경도는 245Hzv이었으나 50% 냉간신선가공으로 450Hv까지 증가했다. 경도값은 시효시간이 증가함에 따라 초기에 증가하다 감소하는 것으로 나타났으며, 시효 초기 경도증가는 $\gamma^{"}$과 $\gamma^{'}$ 상의 석출에 의한 것이며, 최고경도 이후의 경도감소는$\gamma^{'}$상이 $\delta$상으로 변태되었기 때문이다. 냉간가공도가 증가함에 따라 최고경도에 이르는 시간은 감소되어 0, 30, 50%가공재들에 대해 각각 30, 10, 5분으로 나타났다. 이는 냉간가공으로 인해 $\gamma^{'}$ / $\gamma^{'}$ 상의 석출이 촉진되었기 때문이다. 50%가공재의 경우 1116K에서 5분 시효로$\Upsilon^{'}$ 및 $\Upsilon^{'}$상들이 석출되었다. 또한 50%가공재에서는 초기경도 이하로 경도값이 감소되었는데, 이와 같은 경도값의 큰 감소는 재결정이 일어났기 때문이다.