• 한국결정성장학회지
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• 제14권4호
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• pp.174-186
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• 2004

Striations are growth-induced inhomogeneities which hamper the applications of solid-solution crystals and of doped crystals in numerous technologies. Thus the optimized performance of solid solutions often can not be exploited. The inhomogeneity problem can be solved in specific cases by achieving a distribution coefficient one in growth from melts and from solutions. Macrostep-induced striations can be suppressed by controlling the growth mode, by achieving growth on facets thereby preventing step bunching. Thermal striations are commonly assumed to be caused by convective instabilities so that reduced convection by microgravity or by damping magnetic fields was and is widely attempted to reduce such inhomogeneities. Here it will be shown that temperature fluctuations at the growth interface cause striations, and that hydrodynamic fluctuations in a quasi-isothermal growth system do not cause striations. The theoretically derived conditions were experimentally established and allowed the growth of striation-free crystals of $KTa_{1-x}Nb_xO_3$"KTN" solid solutions. Hydrodynamic variations from the accelerated crucible rotation technique ACRT did not cause striations as long as the temperature was controlled within $0.03^{\circ}$ at $1200^{\circ}C$ growth temperature. Alternative approaches to solve or reduce the segregation and striation problems in growth from melts and from solutions are discussed as well.

• Korean Journal of Mathematics
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• 제17권4호
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• pp.507-519
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• 2009

We give a theorem of the existence of the multiple solutions of the Hamiltonian system with the square growth nonlinearity. We show the existence of m solutions of the Hamiltonian system when the square growth nonlinearity satisfies some given conditions. We use critical point theory induced from the invariant function and invariant linear subspace.

• 대한수학회지
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• 제57권6호
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• pp.1573-1590
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• 2020

In this paper, we classify all solutions bounded from below to uniformly elliptic equations of second order in the form of Lu(x) = a_ij(x)D_iju(x) + b_i(x)D_iu(x) + c(x)u(x) = f(x) or Lu(x) = D_i(a_ij(x)D_ju(x)) + b_i(x)D_iu(x) + c(x)u(x) = f(x) in unbounded cylinders. After establishing that the Aleksandrov maximum principle and boundary Harnack inequality hold for bounded solutions, we show that all solutions bounded from below are linear comb_inations of solutions, which are sums of two special solutions that exponential growth at one end and exponential decay at the another end, and a bounded solution that corresponds to the inhomogeneous term f of the equation.

• 한국버섯학회지
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• 제4권3호
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• pp.122-127
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• 2006

4가지 물질의 분말을 10배액, 100배액, 500배액, 1000배액, 1500배액, 2000배액을 농도별로 처리하여 목이버섯 균사생장과 균사밀도를 조사한 결과는 다음과 같다. Senna은 대조구에 비하여 10배액, 100배액, 500배액, 1000배액, 1500배액 2000배액의 6가지 처리 모두가 균사생장과 밀도가 좋았으며 그중 100배액이 가장 좋았다. L-citrulline 분말은 처리농도 500배액이 대조구에 비해 같은 기간 내에 7.86mm/15일이 더 빨리 자랐으며 균사밀도도 좋아 최적 희석배수를 나타내었다. L-carnitine 분말은 100배액은 대조구에 비해 균사생장이 3.4 mm/15일로 촉진되었으며 균사밀도도 촉진되었다. Garcinia cambogia 분말은 대조구에 비해 6가지 희석배수 모두 균사생장이 억제되는 경향을 나타내었다. 10배액의 가장 진한 희석배수에서 가장 균사생장이 억제되었고 1000배액은 거의 대 조구와 비슷한 경향을 나타내었다. 따라서 L-citrulline, L-carnitine, Senna, Garcinia cambogia 순으로 균사생장과 균사밀도에 촉진적으로 작용하였다.

• Journal of Information Processing Systems
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• 제19권1호
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• pp.118-129
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• 2023

The expansion of smart cities drives the growth of data generated from sensor devices, benefitting citizens with enhanced governance, intelligent decision-making, optimized and sustainable management of available resources. The exposure of user data during its collection from sensors, storage in databases, and processing by artificial intelligence-based solutions presents significant security and privacy challenges. In this paper, we investigate the various threats and attacks affecting the growth of future smart cities and discuss the available countermeasures using artificial intelligence and blockchain-based solutions. Open challenges in existing literature due to the lack of countermeasures against quantum-inspired attacks are discussed, focusing on postquantum security solutions for resource-constrained sensor devices. Additionally, we discuss future research and challenges for the growing smart city environment and suggest possible solutions.

• 한국결정성장학회지
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• 제13권2호
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• pp.51-55
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• 2003

The interrelation into nucleation and thermodynamic parameters of solutions has been established by plotting of various dependencies: the enthalpy of dissolution, solubility product and super-solubility on ionic salt radii and also the extent of deviation from an ideal Debye -Huckel model of electrolyte solution on solubility product. The possible methods of perfect crystal growth from aqueous solution have been found a priori by separating of known set of pair values of solubility and super-solubility into no less than six-nine characteristic and distinctive sub-sets.

• 한국결정성장학회지
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• 제1권1호
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• pp.60-65
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• 1991

The hydrothermal growth of $GaPO_{4}$ Single Crystals was carried out by the horizontal temperature gradient method. The most promising solvents for the crystal growth of $GaPO_{4}$ are $H_{3}PO_{4}$ and HCl solutions. Single crystals have been hydothermally grown at temperatures over the range $210-290^{\circ}C$ in these solutions with seed crystals. The glowth rates in HCl solution were higher than that for comparable conditions in $H_{3}PO_{4}$ solution. Morphologies of crystals grown at temperatures below $200^{\circ}C$ tended to be bounded by small major rhombohedral(10$\bar{1}$1) faces. In the temperature range from 200 to $430^{\circ}C$, the single crystals have morphologies bounded by prism (10$\bar{1}$0), small major rhombohedral(10$\bar{1}$1) and minor rhombohedral(01$\bar{1}$1) faces at the early stage, and grew with well developed basal(0001) faces by increasing the growth temperature.

• Restorative Dentistry and Endodontics
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• 제24권2호
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• pp.330-336
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• 1999

In biological systems, the mineral that forms hard tissue is of an apatitic nature, and hydroxyapatite($Ca_5OH(PO_4)_3$: HA) is generally considered as the prototype for such a mineral. Thus, the precipitation of HA, having biological implications, has been the subject of several investigations. Crystal growth studies using HA seeds in supersaturated solutions have enhanced our understanding of the process and mechanism involved in seeded crystal growth. From these studies, it has become apparent that the precipitation rate of HA onto the seed crystals depends on the various conditions, especially on the additives. The relation between the supersaturated solution containing fluoride and the process of HA crystal growth enhances the understanding of mechanism of HA crystal growth. Until recently, the studies have been on the crystal growth of enamel minerals and synthetic HA seeds in the supersaturated solution containing 1~2 ppm fluoride. The purpose of the present investigation is to study the effect that fluoride of high concentration has on the crystal growth kinetics of HA. In order to produce the composition found in the secretory enamel fluid, experimental solutions of 1mM Ca, 3mM P, and 100mM Tris as background electrolyte were used. Then this experimental solutions were added to 0, 2, 4, 6, 8, 10 ppm fluoride. The effect of fluoride at high concentrations on the precipitation was examined in a bench-top crystal growth model adopting a miniaturized reaction column. Chemical analysis was employed for characterization of working solutions before and after the experimentation. Remarkable findings were : 1) the amount of crystal growth was gradually accelerated as the fluoride concentration increased until 6 ppm, but decreased in 8 and 10 ppm fluoride; 2) the amount of fluoride ion consumed in crystal formation was constant despite the increase in fluoride concentration.

• Journal of Plant Biology
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• 제11권1호
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• pp.1-6
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• 1968

The effects of the different temperatures on the amylase activity and growth rate of the rye seedling grown in the solutions containing radioactive sulfur- 35 were studied. The amylase activity of the coleoptiles obtained from the seedlings grown in the solutions of S-35, at 14$^{\circ}C$, appeared to be strongly stimulated in comparison to the control, but the culture temperatures of 22$^{\circ}C$ and 3$0^{\circ}C$ showed the decrease in the amylase activity. The amylase activity of the grains treated with the low intensity of the ratioactive material didn't show clear changes, at any culture temperatures, but the amylase activity of the grains treated with the high intensity of S-35, 50$\mu$c, showed definite decline at the elevated culture temperature, 3$0^{\circ}C$. Similar effects was also found in the growth of the seedlings. However, we would consider the effects of the radioactive materials on the acticity of the amylase and the growth of the seedlings are resulted from the accumulation of the much amount of the radioactive materials, and this accumulation rate depends upon actually the elevation of the culture temperature.

• 한국표면공학회지
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• 제17권2호
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• pp.29-40
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• 1984

The structure of rapidly solidified Al-Si-based alloys and its relationship to subsequent anodic film growth in near neutral and acid solutions have been investigated. Solidification of the alloys proceeds via pre-dendritic nuclei, associated with rugosity of the casting surface, from which cellular-type growth, comprised of aluminium-rich material surrounded by silicon-containing material, emanates. Observation of ultramicrotomed sections of the alloys and their anodic films reveals the local oxidation of the silicon-rich phase and its incorporation into the anodic alumina film, formed in near neutral solutions. Such incorporation occurs but resultant isolation of the silicon-rich phase is not possible for anodizing in phosphoric acid, and a three-dimensional network of the oxidized silicon-containing phase, with continuing development of porous anodic alumina, is observed.