• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1454-1456
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• 2013

The fluctuations in concentrations of reactants dominate the long-time dynamics of the single (A + A ${\rightarrow}$ 0) and two species (A + B ${\rightarrow}$ 0) diffusion-influenced annihilation reactions. Although hierarchical Smoluchowski approaches can provide a systematic and flexible framework to deal with the fluctuation effects, their results are too complicated to be analytically solved. For the efficient numerical calculation of the complicated fluctuation effect terms, we show that the presented point particle approximation is not only practical but also quite accurate for most conditions in diffusion-influenced reaction systems.

• 멤브레인
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• 제7권2호
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• pp.49-56
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• 1997

In order to understand the formation of polymeric membranes or microcellular foams, phase separation phenomena in polymer solutions should be understood. The present review examines the progress made in the understanding of these phenomena, with emphasis on selected polymer-solvent systems. In the case of polymer-solvent systems, coarsening is of particular importance as it may come to dominate or overshadow spinodal decomposition effects within the first minute or few minutes of phase separation. In this article, some of the most important theoretical models of late stage of phase separation are reviewed, and recent experimental studies on coarsening in polymer-solvent systems are studied.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
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• pp.607-607
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• 2003

The purpose of this presentation is to investigate whether the certain therapy resistant bacteria can impair the immune defense system in the pariapical tissue. Recent studies have reported that the facultative or obligatory anaerobic bacteria such as Fusobacterium nucleatum, Enterococcus faecalis and Actinomyces species and Gram positive facultative bacteria Enterococcus faecalis have been shown to dominate in persistent periapical lesion and usually recovered from failed root canal treated cases. Moreover, E. faecalis has been reported to withstand the antimicrobial agent and endure potential starvation and resist the antibacterial effect of calcium hydroxide intracanal medication.(omitted)

• Advances in materials Research
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• 제2권4호
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• pp.195-208
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• 2013

A comprehensive theory of the spin coating technique has been reviewed and the basic principles and parameters controlling the process are clearly highlighted, which include spin speed, spin time, acceleration and fume exhaust. The process generally involves four stages: a dispense stage, substrate acceleration stage, a stage of substrate spinning at a constant rate and fluid viscous forces dominate fluid thinning behaviour and a stage of substrate spinning at a constant rate and solvent evaporation dominates the coating thinning behaviour. The study also considered some common thin film defects associated with this technique, which include comet, striation, chucks marks environmental sensitivity and edge effect and possible remedies.

• 한국전산구조공학회논문집
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• 제28권6호
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• pp.659-666
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• 2015

본 논문에서는 콘크리트 구조물의 층상박리균열 위에서의 손상탐지에 효율적인 충격반향기법에 대해 영향을 끼치는 다양한 영향요소들에 대한 분석을 수행하였다. 충격반향기법에서의 균열 가시화를 위해 층상박리균열위의 동적거동 및 두께를 나타내는 휨 모드 및 충격반향모드(두께 모드)에 영향을 끼치는 균열의 폭/두께(a/h) 비, 균열위의 상대적 가진 점, 측정 점의 위치 등의 시험설정 변수 등을 매개변수적 유한요소해석을 통하여 조사하였다. a/h비는 2보다 클 경우 휨 모드가 지배적이었으며 작을 경우 두께 모드가 지배적이었다. 또한 가진 점, 측정 점 중 어느 하나만 균열 위에 존재할 때도 휨 모드가 지배적이었으며 균열 밖의 범위의 건전한 영역에는 가진 점, 측정 점이 모두 위치하여야 두께 모드가 지배적이었다.

• 한국축산식품학회지
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• 제35권2호
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• pp.171-178
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• 2015

This study aimed to investigate the effects of Lactobacillus plantarum FH185 on the reduction of adipocyte size and gut microbial changes in mice with diet-induced obesity. The strain was found to have a lipase inhibitory activity of 70.09±2.04% and inhibited adipocyte differentiation of 3T3-L1 cells (18.63±0.98%) at a concentration of 100 µg/mL. To examine the effect of the strain supplementation on gut microbial changes in mice with diet-induced obesity, male C57BL/6J mice were fed on four different diets (i.e., A, normal diet (ND); B, high-fat diet (HFD); C, HFD with ABT-3 (10⁹ CFU/day); and D, HFD with L. plantarum FH185 (10⁹ CFU/day)) for 6 wk. According to the results of fecal pyrosequencing, the ratio of Firmicutes to Bacteroidetes in groups C and D was lower than in the control groups at the phylum level. At the family level, Lactobacillaceae in groups C and D was observed to dominate, while Lachnospiraceae in groups A and B was observed to dominate. At the genus level, Lactobacillus in groups C and D was comparatively higher than in groups A and B. To examine the effects of strain supplementation on the reduction of adipocyte size, the left and right epididymal fat pads were quickly isolated after the animals were sacrificed, and the adipocyte sizes were measured. In groups A, C and D, the percentage of 2,000 m² of adipocyte was higher than in the other size of adipocyte, while the percentage of over 5,000 m² of adipocyte was highest in group B. The mean adipocyte size of group D was significantly larger than that of group A, but smaller than that of group B.

• Journal of Forest and Environmental Science
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• 제32권1호
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• pp.74-81
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• 2016

Classified into sub-tree of the growth-form, Acer pseudosieboldianum and Carpinus cordata hardly reach the uppermost canopy with limited height growth potentiality in the natural deciduous forest. However, the two species usually dominate lower stories of the forest, playing an important role in overall ecological characteristics in the forest. Based on the vegetation data of 106 $20m{\times}20m$ sample plots in Mt. Jumbong area, this study was carried out to evaluate ecological constitution by several quantitative analysis so as to understand the mechanism of the natural deciduous forest. The results indicated that individuals of A. pseudosieboldianum and C. cordata were absent or few in overstory, but emerged the most dominant species in midstory and understory, providing adequate proof of the ecological importance. The comparison of indices of succession between presented and predicted values in midstory did not make much difference, suggesting that the species composition would not change much and come close to steady state in midstory and understory. The pair combination of species association noted that A. pseudosieboldianum had significant positive association with C. cordata, Quercus mongolica, and Tilia amurensis had significant positive association with A. pseudosieboldianum, A. pictum subsp. mono and Fraxinus mandshurica but negative association with F. rhynchophylla. Being compared with other major canopy tree species in the study forest, the target species of A. pseudosieboldianum and C. cordata had strong regeneration strategies, partially characterized by large number of saplings and pole sized trees and high ratio of live crown, which indicated high shade tolerance to survive in the limited amount of light under the canopy. Even though A. pseudosieboldianum and C. cordata do not reach and occupy the canopy layer mainly due to the inherent growth form, they would have highest competitive potentiality to prosper and dominate in the midstory of the natural deciduous forest.

• 대한기계학회논문집
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• 제18권7호
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• pp.1713-1721
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• 1994

Intermetallic-matrix composites(IMCs) have the potential of combing matrix properties of oxidation resistance and high temperature stability with reinforcement properties of high specific strength and modulus. One of the major limiting factors for successful applications of these composite at high temperatures is the formation of interfacial reactions between matrix and ceramic reinforcement during composite process and during service. The purpose of the present investigation is to develop a better understanding of the nature of creep fracture mechanisms in a $Ni_{3}Al$ composite reinforced with both $TiB_{2}$ and SiC particulates. Emphasis is placed in the roles of the products of the reactions in determining the creep lifetime of the composite. In the present study, creep rupture specimens were tested under constant ranging from 180 to 350 MPa in vacuum at $760^{\cric}C$. The experimental data reveal that the stress exponent for power law creep for the composite is 3.5, a value close to that for unreinforced $Ni_{3}Al$. The microstructural observations reveal that most of the cavities lie on the grain boundaries of the $Ni_{3}Al$ matrix as opposed to the large $TiB_{2}/Ni_{3}Al$ interfaces, suggesting that cavities nucleate at fine carbides that lie in the $Ni_{3}Al$ grain boundaries as a result of the decomposition of the $SiC_{p}$. This observation accounts for the longer rupture times for the monolicthic $Ni_{3}Al$ as compared to those for the $Ni_{3}Al/SiC_{p}/TiB_{2} IMC$. Finally, it is suggested that creep deformation in matrix appears to dominate the rupture process for monolithic $Ni_{3}Al$, whereas growth and coalescence of cavities appears to dominate the rupture process for the composite.

• 한국수자원학회논문집
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• 제43권4호
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• pp.399-408
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• 2010

본 연구에서는 지형학적 분산을 고려한 특성유속에 따른 Nash 모형 매개변수의 민감도 분석을 실시하였다. 또한 이러한 특성유속의 변동에 따른 순간단위도의 형상의 변화를 수치실험을 통해 비교 분석하였다. 대상유역은 보청천 유역 중 본류에 위치하고 있는 4개의 소유역을 선정하였다. 각 대상유역에 대해 지리정보체계를 이용하여 지표면과 하천의 배수경로길이에 대한 평균과 분산을 산정하였다. 산정된 배수경로길이와 특성유속에 의한 Nash 모형 매개변수를 추정하였다. 추정된 매개변수에 의해 순간단위도를 유도하여 형상의 변화를 비교하였다. 이러한 연구를 통해 도출된 주요 결과는 다음과 같다. Nash 모형 매개변수는 지표면 특성유속에 민감하게 반응함을 알 수 있었다. 또한 순간단위도의 감수부의 형상과 첨두유량은 지표면 특성유속에 지배적인 영향을 받으며, 순간단위도의 상승부의 형상과 첨두시간은 하천 특성유속에 지배적인 영향을 받음을 알 수 있었다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2007년도 춘계학술발표회 논문집
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• pp.413-416
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• 2007

To construct road spatial information database, it is the main object of this study that an analysis of road factors and furthermore this is used to the rescue activities in case of urban disasters. When urban disasters such as earthquake or explosion cause fire and collapses people of the affected region happen to evacuate. But only to manage roads and monitor traffic volume, the road data is designed and managed using digital topographic map so it is short that the design of road spatial data to prevent disasters. In this study, we tried to suggest the evaluative factors of evacuation to design database : road width, traffic volume, the fixed or movable obstacles installed, the surrounding environments that dominate the land-use planning, the uses, materials, structures, sizes, and densities of the buildings. Thus, these could provide fundamental data to determine the disasters management planning for evacuation and rescue activities, to evaluate the riskiness, and to draw up hazard information map.