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Growth of Crack-Free GaN Films on Si(111) Substrates with AlN Buffer Layers
Doek Kyu Kim,Choon Bae Park 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
The characteristics of GaN epitaxial layers grown on silicon (111) substrates with AlN buffer layers by using metalorganic vapor phase epitaxy were investigated for various values of the buffer layer’s thickness. The AlN thickness was found to decrease the stress sufficiently to avoid crack formation in an overgrown, thick (2.6 μm) GaN layer. X-ray diffraction and photoluminescence measurements were used to determine the effect of the AlN thickness on the strain in subsequent GaN layers. For 80-nm-thick AlN, a strong band-edge emission from GaN on Si (111) was observed, and the full width at half maximum of the bound exciton line was as low as 17 meV at 13 K. The 437-arcsec linewidth on the (002) X-ray rocking curve attests to the highly crystalline quality of GaN on Si (111).?
Diversity of Fungal Endophytes in Various Tissues of Panax ginseng Meyer Cultivated in Korea
Park, Young-Hwan,Lee, Soon-Gu,Ahn, Doek-Jong,Kwon, Tae-Ryong,Park, Sang-Un,Lim, Hyoun-Sub,Bae, Han-Hong The Korean Society of Ginseng 2012 Journal of Ginseng Research Vol.36 No.2
Endophytic fungi were isolated from various tissues (root, stem, petiole, leaf, and flower stalk) of 3- and 4-year-old ginseng plants (Panax ginseng Meyer) cultivated in Korea. The isolated endophytic fungi were identified based on the sequence analysis of the internal transcribed spacer (ITS), 1-5.8-ITS 2. A morphological characterization was also conducted using microscopic observations. According to the identification, 127 fungal isolates were assigned to 27 taxa. The genera of Phoma, Alternaria and Colletotrichum were the most frequent isolates, followed by Fusarium, Entrophospora and Xylaria. Although 19 of the 27 taxa were identified at the species level, the remainder were classified at the genus level (6 isolates), phylum level (Ascomycota, 1 isolate), and unknown fungal species (1 isolate). Endophytic fungi of 13 and 19 species were isolated from 3- and 4-year-old ginseng plants, respectively, and Phoma radicina and Fusarium solani were the most frequently isolated species colonizing the tissues of the 3- and 4-year-old ginseng plants, respectively. The colonization frequency (CF%) was dependant on the age and tissue examined: the CFs of the roots and stems in the 3-year-old ginseng were higher than the CF of tissues in the 4-year-old plants. In contrast, higher CFs were observed in the leaves and petioles of 4-year-old plants, and endophytic fungi in the flower stalks were only detected in the 4-year-old plants. In conclusion, we detected diverse endophytic fungi in ginseng plants, which were distributed differently depending on the age and tissue examined.
이상배,박민용,가민호,김현덕,이창훈 연세대학교 산업기술연구소 1991 논문집 Vol.23 No.1
Autonomous action, which corresponds actively to the change of conditions in complicated circumstances, is a fundamental function equired to an intelligent mobile robot. To develop a control system for a mobile robot having such ability adaptable to the circumstances, it is necessary to establish the self-tracing technology which enabies the mobile robot to locate itself in its surrounding circumstances and manipulate its driving part with fiexibility. In this paper, to enable the mobile robot to find its location, the method of representing the route, necessary to make the route map which is used to move from the current position to the destination, is suggested. But the flexible navigation control is required for the mobile robot to navigate along the route map. So fuzzy control algorithm is suggested as navigation control algorithm. Such basic operations in navigation of the mobile robot as going straight, turning, avoiding obstacles are tested.
Diversity of Fungal Endophytes in Various Tissues of Panax ginseng Meyer Cultivated in Korea
Young-Hwan Park,Soon-Gu Lee,Doek Jong Ahn,Tae Ryong Kwon,Sang Un Park,Hyoun-Sub Lim,Hanhong Bae 고려인삼학회 2012 Journal of Ginseng Research Vol.36 No.2
Endophytic fungi were isolated from various tissues (root, stem, petiole, leaf, and fl ower stalk) of 3- and 4-year-old ginseng plants (Panax ginseng Meyer) cultivated in Korea. The isolated endophytic fungi were identifi ed based on the sequence analysis of the internal transcribed spacer (ITS), 1-5.8-ITS 2. A morphological characterization was also conducted using microscopic observations. According to the identification, 127 fungal isolates were assigned to 27 taxa. The genera of Phoma, Alternaria and Colletotrichum were the most frequent isolates, followed by Fusarium, Entrophospora and Xylaria. Although 19 of the 27 taxa were identifi ed at the species level, the remainder were classifi ed at the genus level (6 isolates), phylum level (Ascomycota, 1 isolate), and unknown fungal species (1 isolate). Endophytic fungi of 13 and 19 species were isolated from 3- and 4-year-old ginseng plants, respectively, and Phoma radicina and Fusarium solani were the most frequently isolated species colonizing the tissues of the 3- and 4-year-old ginseng plants, respectively. The colonization frequency (CF%) was dependant on the age and tissue examined: the CFs of the roots and stems in the 3-year-old ginseng were higher than the CF of tissues in the 4-year-old plants. In contrast, higher CFs were observed in the leaves and petioles of 4-year-old plants, and endophytic fungi in the fl ower stalks were only detected in the 4-year-old plants. In conclusion, we detected diverse endophytic fungi in ginseng plants, which were distributed differently depending on the age and tissue examined.
Kim, Sang-Cheol,Park, Soo-Young,Hyoun, Jae-Hee,Cho, Hee-Yeong,Lee, Young-Jae,Kang, Ji-Hoon,Lee, Young-Ki,Park, Doek-Bae,Yoo, Eun-Sook,Kang, Hee-Kyoung Korean Society of ToxicologyKorea Environmental Mu 2004 Toxicological Research Vol.20 No.4
The present study was undertaken to investigate the effects of mistletoe (Viscum album var. coloratum) growing on Carpinus laxiflora BL. on proliferation and differentiation of HL-60 acute promyelocytic leukemia cells. Aqueous extract and its $(NH_2)_2SO_4$ saturated fractions of the mistletoe exhibited potent anti-proliferation activity against HL-60 cells. Moreover, when HL-60 cells were treated with 0~30% and 30~70% $(NH_2)_2SO_4$ saturated fractions of the mistletoe, HL-60 expressed CD 66b or CD 14 cell surface antigens and showed activity to reduce nitroblue tetrazolium, indicating that mistletoe induces the differentiation of HL-60 into granulocytes or monocytes. To understand how mistletoe induces the differentiation, we investigated the expression of molecules for modulating the proliferation and differentiation of leukemia cells, such as c-Myc and myeloblastin. The 0~30% $(NH_2)_2SO_4$ saturated fraction of the mistletoe reduced the mRNA levels of c-Myc and myeloblastin in a time-dependent manner. The results indicate that the mistletoe induces the differentiation of HL-60 cells via the decrease of c-Myc and myeloblastin expressions. Thus, it is suggested that mistletoe has a therapeutic potential for the treatment of acute promyelocytic leukemia.
Sang-Cheol Kim,Soo-Young Park,Jae-Hee Hyoun,Hee-Yeong Cho,Young-Jae Lee,Ji-Hoon Kang,Young-Ki Lee,Doek-Bae Park,Eun-Sook Yoo,Hee-Kyoung Kang 한국독성학회 2004 Toxicological Research Vol.20 No.4
The present study was undertaken to investigate the effects of mistletoe (Viscum album var. coloratum) growing on Carpinus laxiflora BL. on proliferation and differentiation of HL-60 acute promyelocytic leukemia cells. Aqueous extract and its (NH₄)₂SO₄ saturated fractions of the mistletoe exhibited potent anti-proliferation activity against HL-60 cells. Moreover, when HL-60 cells were treated with 0~30% and 30~70% (NH₄)₂SO₄ saturated fractions of the mistletoe, HL-60 expressed CD 66b or CD 14 cell surface antigens and showed activity to reduce nitroblue tetrazolium, indicating that mistletoe induces the differentiation of HL-60 into granulocytes or monocytes. To understand how mistletoe induces the differentiation, we investigated the expression of molecules for modulating the proliferation and differentiation of leukemia cells, such as c-Myc and myeloblastin. The 0~30% (NH₄)₂SO₄ saturated fraction of the mistletoe reduced the mRNA levels of c-Myc and myeloblastin in a time-dependent manner. The results indicate that the mistletoe induces the differentiation of HL-60 cells via the decrease of c-Myc and myeloblastin expressions. Thus, it is suggested that mistletoe has a therapeutic potential for the treatment of acute promyelocytic leukemia.
Kim, Jo-Heon,Alam, Morshedul,Park, Doek Bae,Cho, Moonjae,Lee, Seung-Hong,Jeon, You-Jin,Yu, Dae-Yeul,Kim, Tae Du,Kim, Ha Young,Cho, Chung Gu,Lee, Dae Ho The Korean Society of Pharmacology 2013 The Korean Journal of Physiology & Pharmacology Vol.17 No.5
Retinoids regulate not only various cell functions including proliferation and differentiation but also glucose and lipid metabolism. After we observed a marked up-regulation of cellular retinol-binding protein-I (CRBP-I) in the liver of hepatitis B virus x antigen (HBx)-transgenic (HBx Tg) mice which are prone to hepatocellular carcinoma (HCC) and fatty liver, we aimed to evaluate retinoid pathway, including genes for the retinoid physiology, CRBP-I protein expression, and retinoid levels, in the liver of HBx Tg mice. We also assessed the effect of chronic metformin treatment on HCC development in the mice. Many genes involved in hepatic retinoid physiology, including CRBP-I, were altered and the tissue levels of retinol and all-trans retinoic acid (ATRA) were elevated in the liver of HBx Tg mice compared to those of wild type (WT) control mice. CRBP-I protein expression in liver, but not in white adipose tissue, of HBx Tg mice was significantly elevated compared to WT control mice while CRBP-I protein expressions in the liver and WAT of high-fat fed obese and db/db mice were comparable to WT control mice. Chronic treatment of HBx Tg mice with metformin did not affect the incidence of HCC, but slightly increased hepatic CRBP-I level. In conclusion, hepatic CRBP-I level was markedly up-regulated in HCC-prone HBx Tg mice and neither hepatic CRBP-I nor the development of HCC was suppressed by metformin treatment.