• 대한화학회지
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• 제55권4호
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• pp.570-574
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• 2011

최대 0.20 mm 크기를 가진 아날심 단결정은 $3.00SiO_2$ : $1.50NaAlO_2$ : 8.02NaOH : $454H_2O$ : 5.00TEA의 겔 조성으로부터 합성되어졌다. $Na^+$ 이온으로 완전히 이온교환 된 아날심은 0.1 M 농도의 NaCl 수용액으로부터 준비하였다(이온교환용액의 pH는 NaOH 용액을 첨가하여 6에서 11로 맞추었다). $|Na_{0.94}(H_2O)|[Si_{2.06}Al_{0.94}O_6]-ANA(a=13.703(3){\AA})$의 분자식을 가지는 수화된 아날심 단결정의 구조는 294 K에서 Ibca의 orthorhombic 공간군으로 단결정 X-선 회절기법에 의해 결정되었다. 결정 구조의 최종 에러값은 $R_1/wR_2$= 0.054/0.143에 수렴되었다. 약 15개의 $Na^+$ 이온이 팔면체 배위로 3군데의 비동등한 위치에서 발견되었다. 합성된 아날심의 화학적 조성은 $Na_{0.94}(H_2O)Si_{2.06}Al_{0.94}O_6$ 확인되었으며, Si/Al 비는 단결정 구조 정밀화를 통하여 찾은 양이온의 점유수인 14.79개에 의해 2.19로 결정되었다.

• International Journal of Vascular Biomedical Engineering
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• 제3권2호
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• pp.1-9
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• 2005

Flow-induced dilation of blood vessel is the result of a series of bioreaction in vascular endothelial cells(VEC). Shear stress change by blood flow in human artery or vein is sensed by the mechanoreceptor and responsible for such a chain reaction. The inositol(1,4,5)-triphophate($IP_3$) is produced in the first stage to elevate permeability of the intercellular membrane to calcium ions by which the cytosolic calcium concentration is consequently increased. This intracellular calcium transient triggers synthesis of EDRF and prostacyclin. The mathematical model of this VEC calcium dynamics is reproduced from the literature. We then use the Computational Fluid Dynamics(CFD) technique to investigate the blood stream dictating the VEC calcium dynamics. The pulsatile blood flow in a stenosed blood vessel is considered here as a part of study on thrombogenesis. We calculate the pulsating shear stress (thus its temporal change) distributed over the stenosed artery that is implemented to the VEC calcium dynamics model. It has been found that the pulsatile shear stress induces larger intracellular $Ca^{2+}$ transient plus much higher amount of EDRF and prostacyclin release in comparison with the steady shear stress case. It is concluded that pulsatility of the physiological shear stress is important to keep the vasodilation function in the stenosed part of the blood vessel.

• 문화기술의 융합
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• 제9권3호
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• pp.81-94
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• 2023

본 연구는 2022년 Skytrax가 실시한 항공사 평가 중 최상위 등급에 해당하는 카타르 항공, 싱가포르 항공, 에미레이트 항공, ANA 항공과 9위인 대한항공을 대상으로 Twitter 상의 소셜 네트워크 구조를 비교 분석하여 그 차이점을 규명하는 데 목적이 있다. 이를 위해 본 연구는 소셜 네트워크 분석 프로그램인 NodeXL를 활용하였다. 항공사별 소셜 네트워크의 차이를 비교하기 위한 지표로 Vertex, Unique Edges, Single-Vertex Connected Components, Maximum Geodesic Distance, Average Geodesic Distance, Average Degree Centrality, Average Closeness Centrality, 그리고 Average Betweenness Centrality를 활용한 결과, 종합적으로 싱가포르 항공의 소셜 네트워크가 다른 항공사의 것이 비해 강한 연결망을 형성하고 있는 것으로 나타났다. 또한, 항공사별 소셜 네트워크내에서 정보 및 자원의 흐름뿐만 아니라 상호작용에 큰 영향을 미치는 유력자(Influencer)가 누구이며, 어떤 역할을 하는지를 확인 결과에서도 카타르 항공과 싱가포르 항공이 다른 항공사에 비해 우수한 것으로 평가되었다. 본 연구는 이런 분석 결과를 토대로, 항공사의 소셜 네트워크 활용 필요성과 유용성 제고 차원에서 시사점을 제시하였다.

• 한국식품과학회지
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• 제32권2호
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• pp.317-322
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• 2000

전통 유과의 저장성을 증진하기 위한 시도의 일환으로써 Al증착필름 질소치환포장(AN포장군), PE필름 함기포장(PE포장군) 및 ${\gamma}-oryzanol$첨가 질소치환포장(ANA포장군)을 적용하여 $60^{\circ}C$에 20일 동안 저장하면서 유과의 품질 변화를 살펴보았다. 과산화물가, 산가 및 공액이중결합지방산 함량의 경우, PE포장군과 AN포장군은 저장일수가 늘어남에 따라 점차 증가하였고, 세 포장군 가운데 ANA포장군이 가장 낮은 값을 나타내었다. 반면, hexanal 함량은 AN포장군이 PE포장군보다 높았고, 색도에 있어서도 AN포장군이 PE포장군보다 황색도, 적색도가 더 높았다. 유과의 색도 결과와 관련이 있는 것으로 보이는 저장 중 수분함량은 AN포장군이 PE포장군보다 약 3배 정도 높았다. 유과의 질소치환포장시 완전탈기할 경우 제품의 변형 또는 파손이 일어났고 형태를 유지할 경우 잔존 산소량이 높게 나타났으며, 저장기간이 늘어남에 따라 포장지내 잔존 산소량이 증가하였다. 따라서 유과의 경우 질소치환포장의 적용은 완전 탈기가 어려워 일반 유탕스낵에 비해 효과가 낮으며, 유과의 저장성 증진을 위해서는 항산화제를 병용하는 것이 바람직할 것으로 사료된다.

• Environmental Engineering Research
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• 제17권3호
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• pp.167-174
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• 2012

In situ particle size spectra are obtained from two sequent cruises in order to evaluate the physical consequences of suspended particulate matters caused by episodic storm runoff from the Santa Ana River watershed, an urbanized coastal watershed. Suspended particles from various sources including surface runoff, near-bed resuspension, and phytoplankton are identified in empirical orthogonal function (EOF) analysis and an entropy-based parameterization (Shannon entropy). The first EOF mode is associated with high turbidity and fine particles as indicated by the elevated beam attenuation near the Santa Ana River and Newport Bay outlets, and the second EOF mode explains the suspended sediment dispersal and particle coarsening at the near-surface plume. Chlorophyll particles are also distinguished by negative magnitudes of the first EOF mode, which is supported by the relationship between fluorescence and beam attenuation. The integrated observation between the first EOF mode and the Shannon entropy index accentuates the characteristics of two different structures and/or sources of sediment particles; the near-surface plumes are originated from runoff water outflow, while the near-bottom particles are resuspended due to increased wave heights or mobilizing bottom turbidity currents. In a coastal pollution context, these methods may offer useful means of characterizing particle-associated pollutants for purposes of source tracking and environmental interpretation.

• International Journal of Vascular Biomedical Engineering
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• 제3권1호
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• pp.23-29
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• 2005

We developed a three dimensional cardiac tissue model based on human cardiac cell and mono-domain approximation for action potential propagation. The human myocyte model proposed by ten Tusscher et al. (TNNP model) (2004) for cell electrophysiology and a mono-domain method for electric wave propagation are used to simulate the cardiac tissue propagation mechanism using a finite element method. To delineate non-homogeneity across cardiac tissue layer, we used three types of cardiac cell models. Ansiotropic effect of action potential propagation is also considered in this study. In this 3D anisotropic cardiac tissue with three cell layers, we generated a reentrant wave using S1-S2 protocol. Computational results showed that the reentrant wave was affected by the anisotropic properties of the cells. To test the reentrant wave under pathological state, we simulated a hypertopic model with non-excitable fibroblasts in stochastic manner. Compared with normal tissue, the hypertropic tissue result showed another center of reentrant wave, indicating that the wave pattern can be more easily changed from regular with a concentric focus to irregular multi-focused reentrant waves in case of patients with hypertrophy.

• 대한약리학회지
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• 제3권1호
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• pp.1-4
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• 1967

A colorless needle crystal mass is isolated from rhizom of Cimicifuga heracleifolia Komarov which is used as antipyretic ana antiinflammatory drug. This substance is ientified as 3-hydroxy 4-methoxy cinnamic acid.

• 한국재료학회지
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• 제15권12호
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• pp.756-759
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• 2005

A lead free piezoelectric material, bismuth sodium barium titanate $(Bi_{0.5}Na_{0.5})_{0.94}Ba_{0.06}TiO_3$ (BNBT), was considered as an environment-friendly alternatives for the current PZT system. A perovskite BNBT was synthesized by conventional bulk ceramic processing technique. In order to improve piezoelectric properties, $La_2O_3$ as a dopant was incorporated into the BNBT system up to 0.025 moi, ana the effects on subsequent the piezoelectric ana dielectric properties were systematically investigated. With increasing $La_2O_3$ contents, the equilibrium grain shape was remarkably evidenced and sintered density was increased. Piezoelectric and dielectric properties were s]town to have maximum values at the $La_2O_3$ contents of 0.02 mol. $La^{3+}$ ions seemed to act as a softener in the BNBT system and to enhance dielectric and piezoelectric properties in this study.

• International Journal of Industrial Entomology and Biomaterials
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• 제5권2호
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• pp.189-194
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• 2002

Silkworm diseases are major constraint in silk cocoon production. Among silkworm diseases, white muscar-dine is highly contagious and most common in winter and rainy seasons. It is suggested that hemocytes involve in defense against invasion of Beauveria bassi-ana and systemic fungicide/chemicals prevent the proliferation of fungi in the hemolymph or preventing the growth of the fungi in the body cavity through enhancing the hemocyte mediated defense response. In the present study the influence of systemic fungicide on hematological changes in silkworms infected with Beauveria bassiana was reported. It is observed that the total hemocyte counts increased in the hemolymph up to 5 days post inoculation in systemic fungicide treated batches while in the inoculated control the increase was up to 3 days indicating the positive hemocyte mediated response in silkworm treated with systemic fungicide. After 2 days in the inoculated control as the multiplication and growth of mycelia increased, defense capacity of the silkworm was decreased. The biochemical changes were also observed in the hemolymph of silkworm infected with B. bassiana. In silkworm infected with Beauveria bassi-ana, the total protein content increased whereas total carbohydrate and total lipids decreased as the infection progresses. In the case of systemic fungicide treated batches the increase in total protein content was comparatively higher and decrease in total carbohydrate and lipids were comparatively lower than the inoculated control.

• 한국재료학회지
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• 제15권12호
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• pp.773-779
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• 2005

Properties of Ni-base superalloys of Nimonic 80A alloy system were investigated by the observation of microstructures, precipitates ana hardness as a function of the chemical compositions ana the paths of heat treatment. The higher hardness values showed, the higher Ti/Al ratio among high compositions of Cr and Co element. The lower (Ti+Al) and Fe contents decreased in the same Ti/Al ratio, the higher hardness values showed. This results are considered that coherent deformation was increased with increasing Ti/Al ratio. Hardness showed higher value when Cr contents was $18 wt\%$ less than $21wt\%Cr$. In $3.15 wt\%$Co alloy, $\gamma'$ phase was very fine as around 50nm and, its volume fraction and hardness showed the highest value by 2step-aging treatment.