• Food Engineering Progress
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• v.21 no.4
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• pp.341-350
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• 2017

The relationship of in vitro starch digestibility and gel strength was investigated at various concentrations (10-30%) of rice cultivars with different amylose contents (27.9, 17.9, and 5.2%). As the rice flour concentration increased, predicted glycemic index decreased, but gel strength increased regardless of amylose contents. Gel strength correlated strongly with amylose content, whereas in vitro starch digestibility was more highly affected by rice flour concentration than by amylose contents. Moreover, the impact of degree of gelatinization on in vitro starch digestibility of high amylose rice was also examined in terms of structural features and rheological properties. The digestion rate of fully gelatinized flour was 1.7 times higher than that of native flour, while the disrupted structure with a different gelatinization degree during starch digestion was visually demonstrated through the X-ray diffraction and molecular distribution analysis. The rice flour changed from an A-type to a V-type pattern and showed difference in crystalline melting. The low molecular weight distribution increased with increasing degree of gelatinization during starch digestion. The apparent viscosity also increased with degree of gelatinization. These results demonstrated that the starch digestibility of rice was more affected by concentration than by amylose content, as well as by the degree of gelatinization due to structural difference.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.403.2-403.2
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• 2016

Porous materials play a significant role in energy storage and conversion applications such as catalyst support for polymer electrolyte membrane fuel cell. In particular, hierarchical porous materials with both micropores (poresize, ${\delta}$ < 2 nm) and regularly arranged mesopores (2 nm < ${\delta}$ < 50 nm) are known to greatly enhance the efficiency of catalytic reactions by providing enormous surface area as well as fast mass transport channels for both reactants and products from/to active sites. Although it is generally agreed that the microscopic structure of the porous materials directly affects the performance of these catalytic reactions, neither detailed mechanisms nor fundamental understanding are available at hand. In this study, we propose an atomistic model of hierarchical nanostructured porous carbons (HNPCs) in molecular dynamics simulations. By performing a systematic study, we found that structural features of the HNPC can be independently altered by tuning specific synthesis parameters, while remaining other structures unchanged. In addition, we show some structure-property relations including mechanical and gas transport properties.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.705-712
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• 2008

Sweet potato starch was modified using Thermus aquaticus $\alpha$-1,4-glucanotransferase ($Ta{\alpha}GT$), and its structural and rheological properties were investigated. $Ta{\alpha}GT$-modified starch had a lower amylose level and molecular weight than raw starch. The chain length distribution showed an increased number of short and long branched chains and the formation of cycloamyloses. Compared with raw starch, $Ta{\alpha}GT$-modified starch displayed a lower gelatinization enthalpy and a wider melting temperature range. The X-ray diffraction of $Ta{\alpha}GT$-modified starch was a weak V-type pattern with distinct sharp peaks at 13 and $20^{\circ}$. Scanning electron micrographs of modified starch exhibited big holes on the surface and the loss of granular structure. The frequency sweep measurement revealed that the gel of $Ta{\alpha}GT$-modified starch was more rigid than raw starch gel. However, the structure of modified starch gel was destroyed by heating at $75^{\circ}C$, and a firm gel was re-formed by subsequent storage at $5^{\circ}C$, indicating thermoreversible property.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.197-200
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• 1999

The polyacene materials prepared from phenol resine at relatively low temperature(550~75$0^{\circ}C$) show a highly Li-doped state up to $C_2$Li state without liberation of Li cluster. We prepared each polyacenic materials various temperature and investigated electrochemical property. We tried to change the mole ratio of [H]/[C] that was 0.24~0.4 range and finally found that the further discussion of improvements of battery materials. The X-ray structural analyses have shown that this material is essentiallly amorphous with loose structure in molecular size order. This structure ensures that the PAS battery has both reliability on repetitive doping-undoping processes and higher energy density than other batteries. The PAS electrode has been confirmed to show good stability and reversibility.

• Korean Journal of Metals and Materials
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• v.48 no.2
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• pp.101-108
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• 2010

The local structural states of amorphous alloys have been depicted previously via short-range orders (SROs). However, the concept of SROs alone is inadequate and sometimes insufficient to explain the structure-property relation of the amorphous alloys. In this study, we propose new types of medium-range building structures that affect the mechanical properties, plasticity in particular. Using a combination of molecular dynamics simulations and the Voronoi tessellation method, we demonstrate a three-dimensional configuration of icosahedral medium-range orders (I-MROs) and elucidate how these icosahedral orders evolve by the application of shear deformation. It was observed that the structural stability of the icosahedral orders relies largely on how they are linked via percolation and this linking is explained in detail.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.123-124
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• 2008

We investigate characteristics of J-aggregation as take advantage of LB technic. In order to confirm the applications possible for the molecular electronic device, the morphological properties of merocyanine dye were investigated by AFM. $\pi$-A curves investigated the surface pressure of the LB film from a liquid to a solid state ranged between 90 and 100 mN/m. We observed aggregation and it's characteristics by using visible reflection spectroscopy. This paper focuses on results obtained in mercocyanide dye. When LB films of merocyanine dye are mixed with arachidic acid, J-aggregate formation is exhibited. J-aggregate formation has been serving as typical systems in revealing the physical and structural aspects of nano-sized molecular aggregates constructed as muiltilayers.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.568-569
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• 2003

Functional cosmetic ingredients such as L-ascorbic acid, retinoic acid, indole-3-acetic acid, salicylic acid, acidic dye(indigo carmine) are intercalatively encapsulated by skin-friendly metal hydroxides and oxides matrices. Such functional organic-inorganic nanohybrids are realized via chemical coprecipitation and surface coating reactions. The hetero-structural nature of these nanohybrids, their particle morphology and textural characterizations are mainly discussed on the basis of powder X-ray diffraction, electron microscopies, and high performance liquid chromatographic analyses. The cosmetic ingredients encapsulated in inorganics show greatly improved storage stability, sustained releasing property as well as higher transdermal transfer efficiency.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.660-661
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• 2008

Nanotubes fabricated with diverse materials show different hydrophobic properties. The hydrophobic property is one of key properties for possible applications to ion channels due to their affinity. This study focuses on the structures of water molecules inside nanotubes with varying hydrophobicity using molecular dynamics simulation. Hydrophobicity here is determined by varying the attraction term in Lennard-Jones potential. The number of water molecules inside hydrophilic nanotubes increase, as expected, and their mobilities also increase. This trend is rather discrete with increasing number of water molecules and this discreteness is attributed to hydrogen bond. We plan to perform energy analysis to understand these structural results.

• Korean Journal of Computational Design and Engineering
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• v.14 no.6
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• pp.404-414
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• 2009

In the computational molecular analysis, 3D structural comparison for protein searching plays a very important role. As protein databases have been grown rapidly in size, exhaustive search methods cannot provide satisfactory performance. Because exhaustive search methods try to handle the structure of protein by using sphere set which is converted from atoms set, the similarity calculation about two sphere sets is very expensive. Instead, the filter-and-refine paradigm offers an efficient alternative to database search without compromising the accuracy of the answers. In recent, a very fast algorithm based on the inter-atomic distance has been suggested by Ballester and Richard. Since they adopted the moments of distribution with inter-atomic distance between atoms which are rotational invariant, they can eliminate the structure alignment and orientation fix process and perform the searching faster than previous methods. In this paper, we propose a new 3D shape descriptor. It has properties of the general shape distribution and useful property in screening the molecular database. We show some experimental results for the validity of our method.

• Applied Science and Convergence Technology
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• v.26 no.4
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• pp.86-90
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• 2017

We have reported structural and optical properties of self-assembled InAs/GaAs quantum dot (QD) grown by molecular beam epitaxy with different arsenic to indium flux ratios (V/III ratios). By increasing the V/III ratio from 9 to 160, average diameter and height of the InAs QDs decreased, but areal density of them increased. The InAs QDs grown under V/III ratio of 30 had a highest-aspect-ratio of 0.134 among them grown with other conditions. Optical property of the InAs QD was investigated by the temperature-dependent photoluminescence (PL) and integrated PL. From the temperature dependence PL measurements of InAs QDs, the activation energies of $E_{a1}$ and $E_{a2}$ for the InAs QDs were obtained $48{\pm}3meV$ and $229{\pm}23meV$, respectively. It was considered that the values of $E_{a1}$ and $E_{a2}$ are corresponded to the energy difference between ground-state and first excited state, and the energy difference between ground-state and wetting layer, respectively.