• 한국미생물·생명공학회지
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• 제27권1호
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• pp.1-7
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• 1999

A fungus, Penicillium sp. PS-113, isolated from soil showed the high phosphate-solubilizing activity in patato dextrose broth-rock phosphate to produce free phosphates to the culture broth with the concentrations of 585 ppm against rock phosphate. In this medium, the optimum temperature and initial pH to solubilize rock phosphate were 30$^{\circ}C$ and pH 7.5, respectively. In order to make the mass production of the conidia from this fungus, we cultured in on various solid-based media like barley, corn, wheat, rice, rice bran, and compost. As a result, the fungus highly produced conidia ranging from 2.1 to $5.1{\times}10_9$ conidia/g${\cdot}$media on these solid media except compost-based medium, which was 0 times less than others. Effects of inoculation of the phosphate solubilizing fungus as a biofertilizer were studied in perlite-based pot cropped with Zea mays Suwon 19. Inoculation of Penicillium sp. PS-113 increased in plant height (1.4 times), plant weight (5.2~8.1 times) and root length (1.1~1.2 times) at 60-day cultivation, compared to Hogland solution either without $NH_4H_2PO_4$ or displace $NH_4H_2PO_4$ to powdered rock phosphate, a phosphorus source for plant growth.

• 한국세라믹학회지
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• 제33권4호
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• pp.405-410
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• 1996

The partial substitution of LiTaO3 with Al2O3 caused the variation of dielectric properties and a lower melting temperature yielding an easier growth of single crystal. The lattice constants and Raman band broadening were measured for the LiTaO3 solid solution in which the cations of Li+ and Ta5+ were partially substituted by Al3+ cation. The LiTaO3 type limit phases were obtained. ; Li1.15Al0.45Ta0.7O3 for cationic excess Li1.15Al0.45Ta0.7O3 for stoichiometry Li0.85Al0.05TaO3 for cationic deficit. The second phase was formed beyond the solubility limit. The limit phase (Li0.85Al0.05TaO3) in the region of cationic deficit showed the lowest Cuire temperature of 61$0^{\circ}C$ and melting point of 152$0^{\circ}C$ compared to the solid solutions in other regions (TMp=1$650^{\circ}C$, Tc=69$0^{\circ}C$ for LiTaO3)

• Mycobiology
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• 제45권3호
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• pp.172-177
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• 2017

The genus Paxillus is characterized by the difficulty of species identification, which results in reproducibility problems, as well as the need for large quantities of fungal inoculum. In particular, studies of Paxillus ammoniavirescens have reported divergent results in the in vitro growth while little is known of its capacity to degrade organic matter. For all the above, and assuming that this variability could be due to an inappropriate culture media, the aim of this study was to analyse growth in different culture media (MMN, MS, and 1/2 MS) and in the case of MMN in presence/absence of two types of organic matter (fresh litter and senescence litter) to probe the saprophytic ability of P. ammoniavirescens. We also evaluated the effects of pH changes in the culture media. Growth kinetics was assessed by weekly quantification of the area of growth in solid culture media over 5 wk, calculating the growth curves and inflection points of each culture media. In addition, final biomass after 5 wk in the different culture media was calculated. Results showed that best culture media are MS and 1/2 MS. Moreover, an improvement in growth in culture media containing decomposing fall litter was observed, leading to confirm differences in the culture media of this species with others of the same genus. Further, we established that all growth media suffered a significant acidification after fungal growth.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.462-462
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• 2013

Gallium Oxide (Ga2O3) has been widely investigated for the optoelectronic applications due to its wide bandgap and the optical transparency. Recently, with the development of fabrication techniques in nanometer scale semiconductor materials, there have been an increasing number of extensive reports on the synthesis and characterization of Ga2O3 nano-structures such as nano-wires, nanobelts, and nano-dots. In contrast to typical vaporliquid-solid growth mode with metal catalysts to synthesis 1-dimensional nano-wires, there are several difficulties in fabricating the nanostructures by using sputtering techniques. This is attributed to the fact that relatively low growth temperatures and higher growth rate compared with chemical vapor deposition method. In this study, Ga2O3 chestnut burr were synthesized by using radio-frequency magnetron sputtering method. In contrast to typical sputtering method with sintered ceramic target, a Ga2O3 powder (99.99% purity) was used as a sputtering target. Several samples were prepared with varying the growth parameters, especially he growth time and the growth temperature to investigate the growth mechanism. Samples were characterized by using XRD, SEM, and PL measurements. In this presentation, the details of fabrication process and physical properties of Ga2O3 nano chestnut burr will be reported.

• 한국결정성장학회지
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• 제6권2호
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• pp.238-246
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• 1996

$\beta$-SiC와 AIN의 혼합분말로부터 열간가압소결에 의하여 고밀도의 SiC-AIN 고용체가 $1870^{\circ}C$에서 $2030^{\circ}C$ 사이의 온도범위에서 제조되어졌다. 온도와 SiC/AIN의 비 및 seed의 존재에 따라 AIN과 $\beta$-SiC(3C) 분말의 반응은 2 H (wurzite) 구조로의 전이를 나타내었다. 결정상들은 SiC-rich 및 AIN-rich 고용체로 구성되었다. $2030^{\circ}C$, 1시간에서 5 wt%의 $\alpha$-SiC seed를 첨가한 50 % AIN/50% SiC의 조성에 대하여 완전한 고용체가 얻어졌으며, 미세구조가 비교적 균일한 2 H상의 결정립 크기를 가지고균일한 성장경향을 나타내었다. SiC-AIN 고용체에 있어서 $\alpha$-SiC seed의 변수가 전이기구 및 결정립의 크기와 모양을 비롯한 결정립 크기의 분포, 조성의 불균일성과 구조적 결함 등에 영향을 미칠 수 있었다.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.587-590
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• 2013

N-vinyl-2-pyrrolidone (NVP)에 포함된 불순물인 2-pyrrolidone을 제거하기 위해 용융결정화가 이용될 수 있으며, 그 기본 연구로써 두 물질의 고-액 상평형을 측정하였다. 시차주사 열량계(DSC)와 결정화기를 이용하여 얻어진 두 실험결과는 비슷한 경향을 보였으며, NVP와 2-pyrrolidone으로 구성된 2성분계 혼합물이 공융계를 형성함을 보였다. 간단한 열역학 식을 이용하여 혼합물의 상평형과 공융점(eutectic point)을 계산하였으며 실험결과와 비교적 잘 일치하였다. 결정화 공정의 설계에 중요한 요소인 결정성장속도를 알기 위해 판형 결정화기를 이용하여 시간에 따른 NVP 결정의 두께를 측정하였다. 냉각온도가 낮을수록 NVP의 결정성장속도가 증가하였다. 실험데이터로부터 상관된 열전달계수는 결정의 성장 거동을 잘 설명하였다.

• 한국재료학회지
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• 제19권11호
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• pp.588-595
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• 2009

The knowledge of grain growth of carbide particles is very important for manufacturing micrograined cemented carbides. In the present study, continuous and discontinuous grain growth in WC-Co and WC-VC-Co cemented carbides is investigated using the Monte Carlo computer simulation technique. The Ostwald ripening process (solution/re-precipitation) and the grain boundary migration process are assumed in the simulation as the grain growth mechanism. The effects of liquid phase fraction, grain boundary energy and implanted coarse grain are examined. At higher liquid phase content, mass transfer via solid/liquid interfaces plays a major role in grain growth. Growth rate of the implanted grain was higher than that of the matrix grains through solution/re-precipitation and coalescence with neighboring grains. The results of these simulations qualitatively agree with experimental ones and suggest that distribution of liquid phase and carbide particle/carbide grain boundary energy as well as contamination by coarse grain are important factors controlling discontinuous grain growth in WC-Co and WC-VC-Co cemented carbides. The contamination by coarse grains must by avoided in the manufacturing process of fine grain cemented carbides, especially with low Co.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.125.2-125.2
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• 2016

Semiconductor nanowires are essential building blocks for various nanotechnologies including energy conversion, optoelectronics, and thermoelectric devices. Bottom-up synthetic approach utilizing metal catalyst and vapor phase precursor molecules (i.e., vapor - liquid - solid (VLS) method) is widely employed to grow semiconductor nanowires. Al has received attention as growth catalyst since it is free from contamination issue of Si nanowire leading to the deterioration of electrical properties. Al-catalyzed Si nanowire growth, however, unlike Au-Si system, has relatively narrow window for stable growth, showing highly tapered sidewall structure at high temperature condition. Although surface chemistry is generally known for its role on the crystal growth, it is still unclear how surface adsorbates such as hydrogen atoms and the nanowire sidewall morphology interrelate in VLS growth. Here, we use real-time in situ infrared spectroscopy to confirm the presence of surface hydrogen atoms chemisorbed on Si nanowire sidewalls grown from Al catalyst and demonstrate they are necessary to prevent unwanted tapering of nanowire. We analyze the surface coverage of hydrogen atoms quantitatively via comparison of Si-H vibration modes measured during growth with those obtained from postgrowth measurement. Our findings suggest that the surface adsorbed hydrogen plays a critical role in preventing nanowire sidewall tapering and provide new insights for the role of surface chemistry in VLS growth.

• 한국균학회지
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• 제23권2호통권73호
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• pp.105-113
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• 1995

한국교원대학교 주변의 아카시아림 및 상수리나무와 아카시아의 혼합림에서 민자주방망이버섯(L. nuda)을 채집하여 균사를 순수분리하였다. 분리된 균사와 농진청 균이과에서 분양 받은 균사를 시료로 수종의 기질에 따른 균사의 성장을 나무 건중량과 탄산가스 발생량으로 측정하였다. 이 결과 아카시아, 뽕나무, 느티나무 순으로 균사의 성장을 나타냈다. 아카시나무 톱밥, 조 및 옥수수를 이용한 고형발효를 한 결과 균사의 성장에 관련된 성장곡선은 그렸으나, 자실형성을 하지 못하였다. 그러나, 앞으로 유망한 식용버섯으로 다른 수종의 나무에 자라는 균사를 얻었으며, 자실체 형성을 위하여서는 많은 연구가 필요하다.

• 한국결정성장학회지
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• 제9권4호
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• pp.424-431
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• 1999

The reproducibility of successive growth of $Bi_{12}TiO_{20}$ (BTO) single crystlas using a top-seeded solution growth (TSSG) pulling method was evalutated by measuring the lattice constants and their standard deviations. A substantial phase diagram in the region close to the stoichiometric BTO was established expermentally for this purpose, and the existence of a retrograde solid solution close to a BTO was clarified. It was emphasized that a starting solution, with a 10.0~10.1 mol% $TiO_{2}$ concentration, results in large single crystals with a highly homogeneous lattice constant of within ${\pm}1{\times}10^{-4}\AA$, when the solidified fraction of the grown crystal is less than about 45 %. A wavelength dispersion of refractive index was measrued for the first time, and it was verified that the refractive index of BTO is larger than that of BSO($Bi_{12}TiO_{20}$), allowing the voltage sensitivity of EOS higher than the case with BSO as a probe head.