• Korean Journal of Crystallography
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• v.1 no.1
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• pp.29-34
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• 1990

Single crystals of the peritectic compound MgTiO3 up to 8 m diameter and 100mm long along the [1010] axis. were yon by the travelling solvent floating zone technique using a halogen lamp image furnace. The grown single crystal. which shows a solid solution range at high temperature, exsolves TiO2 component if it is annealed very slowly to room termperature. Grown boules were black but become translucent with pinkish brown color after tempering at 1100 t for 8-10 hours in oxygen atmosphere and showed distint chatoyancy along the (0001) plane. The grown crystal can be used as a new modified cat's eye gemstone. The optimum conditions were as follows ;Sintering temperature of the charge rod, 1300℃ the growth rate, 2-2.5mmh and the composition of the charge rod in molar ratio. MgO : TiO2 : 1:1.05.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.5
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• pp.359-362
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• 2001

The production of an extracellular polysaccharide, EPS-R, from the marine bacterium Hahella chejuensis was investigated at various aeration rates in a batch culture. Higher aeration rate resulted in enhanced EPS production and increased the viscosity of the culture broth. At an aeration rate of 1.5 vvm, EPS-R (12.2 g/L) was obtained with a yield (Y$\_$p/s) of 0.6 from the STN medium after 72 h of cultivation. The H. chejuensis cells changed rod morphology to a short-rod form in the stationary growth phase.

• 연구논문집
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• s.33
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• pp.123-135
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• 2003

Using the residence time calculated by computer simulation for temperature and gas velocity distribution in CVC reactor, the kinetics on the formation of $TiO_2$ nano powder was analyzed for coagulation process, After abrupt increase of particle size at initial growth stage (< 0.2 $\mus$ ), the particle grew in proportion of cubic root to time. The numerically calculated particle sizes well agreed with the experimental results. However, the coarse rutile $TiO_2$ powders having the particle size of over 40 nm were formed on the surface of quratz rod in the reactor. it is thought that the fine anatase particles condensed on quratz rod were sintered in a heated CVC reactor to grow and transform to coarse rutile phase, and the critical size for phase transformation anstase-to-rutile was around 25 nm tn this study.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.318-331
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• 1995

The c - axis oriented single crystal of $LiNbO_3$ and $LiNbO_3$ : 5mol%MgO was success-fully grown by Floating zone method using halogen lamp as a heat source. The effects of the sintering condition of the feed rod and the atmosphere gas during the crystal growth on the be havior of the feed rod/melt interface were studied for growing crystal with the high quality, and then, the optimum growth conditions were determined by studying the experimental param eters, such as gas flow rate, pulling rate, rotation speeds of the feed rod and the seed. The grown crystals were analyzed using the chemical etching to observe the tch pattern and the ICP (Inductively Coupled Plasma) to determine the composition uniformity and the impurity content of Fe. The effects of additive (5 mol % MgO) on the transmittance and refractive index was, also, analyzed. In order to compare the nonlinear optical oharacteristics of $LiNbO_3$ with those of the other optical materials, the nonlinear optical refractive index ($n_2$) was calcu l lated using the measured refractive index.

• Journal of Microbiology
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• v.35 no.4
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• pp.284-289
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• 1997

A Gram (-), rod-shaped bacterium $2.3{\sim}2.8{\times}0.45{\mu}m$ in size which exhibited growth-inhibiting effects against a cyanobacterium (Anabaena cylindrica) was isolated from Daechung Dam Reservoir. This isolate was identified as Moraxella sp. and designated Moracella sp. CK-1. Hollow zones formed around bacterial colonies on the cyanobacterial lawn. In a mixed-culture of A. cylindrica and the isolate, each microorganism grew inverse-proportionally, and the cyanobacterial vegetative cells completely disappeared within 24 hours. On treatment with Moraxella sp. CK-1, cell walls of A. cylindrica disappeared, but sheathes remained in a more electron dense form. The unit membrane such as thylakoidal membrane was stable to bacterial lysing activity. This bacterium showed a broad action spectrum against cyanobacteria. The growth-inhibiting activity of Moracella sp. CK-1 against A. cylindrica is believed to be performed through the excretion of active substances.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.6
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• pp.229-233
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• 2005

Novel process was tried to obtain micro-porous ceramic body containing continuous pore channel. $MgAl_2O_4/MgO$ eutectic fibers and rods have been grown successfully by the micro-pulling-down method, and the microstructures and optical characterizations of grown crystals were performed. $MgAl_2O_4/MgO$ eutectic fibers of $0.3{\sim}1mm$ in diameter and about 500 mm in length, and the rods having 5 mm in diameter with approximately 60 mm in length have been grown with the $6{\sim}120mm/hr$ of growth speed. The eutectic fibers showed homogeneous microstructure in which MgO fiber aligned to the growth direction in the $MgAl_2O_4$ (spinel) matrix. The grown crystals looked semitransparency under naked eyes. Optical and orientational characterizations were performed. The second phase of MgO (periclase) was easily removed by selective etching with hydrochloric acid, and then porous bodies were obtained.

• Korean Journal of Materials Research
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• v.31 no.9
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• pp.481-487
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• 2021

ZnO particles are successfully synthesized at 150 ℃ for 30 min using zinc acetate as the Zn source and 1,4-butanediol as solvent using a relatively facile and convenient glycol process. The effect of ammonium hydroxide amounts on the growth behavior and the morphological evolution of ZnO particles are investigated. The prepared ZnO nanoparticle with hexagonal structure exhibits a quasi-spherical shape with an average crystallite size of approximately 30 nm. It is also demonstrated that the morphology of ZnO particles can be controlled by 1,4-butanediol with an additive of ammonium hydroxide. The morphologies of ZnO particles are changed sequentially from a quasi-spherical shape to a rod-like shape and a hexagonal rod shape with a truncated pyramidal tip, exhibiting preferential growth along the [001] direction with increasing ammonium hydroxide amounts. It is demonstrated that much higher OH^- amounts can produce a nano-tip shape grown along the [001] direction at the corners and center of the (001) top polar plane, and a flat hexagonal symmetry shape of the bottom polar plane on ZnO hexagonal prisms. The results indicate that the presence of NH⁴⁺ and OH^- ions in the solution greatly affects the growth behaviors of ZnO particles. A sharp near-band-edge (NBE) emission peak centered at 383 nm in the UV region and a weak broad peak in the visible region between 450 nm and 700 nm are shown in the PL spectra of the ZnO synthesized using the glycol process, regardless of adding ammonium hydroxide. Although the broad peak of the deep-level-emission (DLE) increases with the addition of ammonium hydroxide, it is suggested that the prominent NBE emission peaks indicate that ZnO nanoparticles with good crystallization are obtained under these conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.57-62
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• 1994

$YbFeCoO_4$ single crystal was grown by floating zone method. The atmospheric condition of the growth was controlled in air and the growth rate was 1~2 mm/hr. After melting the feed rod of the composition of $YbFeCoO_4$, $YbFeCoO_4$ was decomposed to $YbFeCoO_4$ and CoO phase in the initial state of the growth. The liquid composition, however, changed to the direction of the eutectic point along the liquidus line and then stopped at the point in which $YbFeCoO_4$ single crystal could be grown. The growth direction of the crystal was preferred orientation [110], perpendicular to the c-axis in the hexagonal system due to using the polycrystalline seed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.11a
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• pp.55-62
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• 2001

An electrolytic copper rod was drawn up to $90\%$ in area reduction and annealed under various conditions. The EBSD measurement of the drawn wire showed that in the center region the <111> + <100> fiber duplex texture was dominant, while in the middle and surface regions relatively defused textures developed with a little higher density in <11w>//wire axis. The inhomogeneous texture in the deformed wire gave rise to the inhomogeneous microstructure and texture after annealing. The annealing texture could be classified into the recrystallization texture developed during low temperatures and at the early stage at a high temperature and the growth texture developed after a prolonged annealing at the high temperature. The recrystallization temperature could be explained by the strain energy release maximization model and the growth texture was discussed based on the grain boundary mobility anisotropy.

• The Microorganisms and Industry
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• v.18 no.3
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• pp.23-33
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• 1992

The general characteristics of campylobacters and related organisms (e.g., species of the genera Helicobacter and Wolinella, Bacteroides ureolyticus, and Bacteroides gracilis) are as follows: slender, non-sporeforming, gram-negative, vibroid bacteria (helical- or spiral- shpaed; except that B. ureolyticus and B. gracilis are straight-rod), 0.2-0.5 .mu.m in width and 0.5 .mu.m in length. (Smibert, 1984; Penner, 1988). The species of genus Campylobacter and related organisms are chemoorganotrophs; however, they neither oxidize nor ferment carbohydrates and instead obtain energy from amino acids, the salts of tricarboxylic acids (TCA) cycle intermediates, the salts of organic acids, or, in some species, H$\_$2/. With regard to their oxygen responses for growth, they all are microaeophilic i.e., they are capable of oxygen-dependent growth (respiring with oxygen as a terminal electron acceptor) but can not grow in the presence of a level of oxygen equivalent to that present in an air atmosphere (21% oxygen). This review will take interests in how these microorganisms response to oxygen for growth and what repiratory types they have.