• Korean Institute of Interior Design Journal
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• v.18 no.2
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• pp.80-92
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• 2009

Natural history museums preserve and manage the creatures living in each country, so they play unique roles for bio-diversity, and in fact, their roles are really instrumental for the collection, preservation, research, exhibition and education of creatures in the 21st century. Therefore, this research has the purpose to survey the status of our country's existing natural history museums, analyze their visual perception space structural characteristics, and ultimately utilize their characteristics as basic data in planning out and designing spaces of natural history museums to be established later on. As for the research scope, the research selected as research subjects 7 natural history museums that currently have composite set of open type and mixed type and have been accommodating comparatively active exhibitions since 2000 among 10 or so natural history museums in our country. Research method is that the research analyzed the exhibition spaces of 7 natural history museums by using depthmap program which can analyze space with visual graph analysis function, and analyzed the visibility among unit areas by each natural history museum integration and exhibition contents composition. In such analysis method, the research was able to quantitatively analyze the visual characteristics of exhibition space that induces and adjusts the motion of audience. Visual perception quantitative analysis as in this research will enhance exhibition design by considering the correlation between audience and exhibited items when planning out natural history museums space to be established later on.

• Steel and Composite Structures
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• v.15 no.6
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• pp.585-603
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• 2013

Generally the required strength and stiffness of an I-shaped beam to the box-shaped column connection is achieved if continuity plates are welded to the column flanges from all sides. However, welding the forth edge of a continuity plate to the column flange may not be easily done and is normally accompanied by remarkable difficulties. This study was aimed to propose an alternative for box columns with continuity plates to diminish such problems. For this purpose a double-web I-shaped column was proposed. In this case the strength and rotational stiffness of the connection was provided by nearing the column webs to each other. Finite element studies on about 120 beam-column connections showed that the optimum proportion of the distance between two column webs and the width of the column flange (parameter ${\beta}$) was a function of the ratio of the beam flange width to the column flange width (parameter ${\alpha}$). Hence, based on the finite element results, an equation was proposed to estimate the optimum value of parameter ${\beta}$ in terms of parameter ${\alpha}$ to achieve the highest connection performance. Results also showed that the strength and ductility of post-Northridge connections of such columns are in average 12.5 % and 54% respectively higher than those of box-shaped columns with ordinary continuity plates. Therefore, a double-web I-shaped column of optimum arrangement might be a proper replacement for a box column with continuity plates when beams are rigidly attached to it.

• Computers and Concrete
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• v.26 no.2
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• pp.127-136
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• 2020

There is an inherent randomness for concrete microstructure even with the same manufacturing process. Meanwhile, the concrete material under the aqueous environment is usually not fully saturated by water. This study aimed to develop a stochastic micromechanical framework to investigate the probabilistic behavior of the unsaturated concrete from microscale level. The material is represented as a multiphase composite composed of the water, the pores and the intrinsic concrete (made up by the mortar, the coarse aggregates and their interfaces). The differential scheme based two-level micromechanical homogenization scheme is presented to quantitatively predict the concrete's effective properties. By modeling the volume fractions and properties of the constituents as stochastic, we extend the deterministic framework to stochastic to incorporate the material's inherent randomness. Monte Carlo simulations are adopted to reach the different order moments of the effective properties. A distribution-free method is employed to get the unbiased probability density function based on the maximum entropy principle. Numerical examples including limited experimental validations, comparisons with existing micromechanical models, commonly used probability density functions and the direct Monte Carlo simulations indicate that the proposed models provide an accurate and computationally efficient framework in characterizing the material's effective properties. Finally, the effects of the saturation degrees and the pore shapes on the concrete macroscopic probabilistic behaviors are investigated based on our proposed stochastic micromechanical framework.

• Elastomers and Composites
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• v.36 no.1
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• pp.22-29
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• 2001

For a purpose of recycling of waste tires, composites of 10-60wt% recycled tire crumb blended with high density polyethylene(HDPE) were prepared, and their mechanical properties such as tensile strength, elongation at break, tensile modulus and impact strength were investigated as a function of tire crumb content. Ethylene-acrylic acid(EAA) copolymer was introduced by 10phr as a compatibilizer and the mechanical properties of the composites were measured. For the blend composition of 40wt% tire crumb content showing improved impact strength, the mechanical properties were measured by varying the EAA content of 5-15phr. All blends, whether modified or unmodified, showed a gradual improvement in impact strength as the tire crumb content increased, but the other properties decreased compared with the pure HDPE. In particular, the addition of EAA copolymer to the tire crumb content over 30wt% showed substantial improvement in impact strength. There was no significant effect of tire crumb size on impact strength of the composites.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.28-33
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• 2011

This paper describes the fabrication of AlN thin films containing iron and iron nitride particles, and the magnetic and electrical properties of such films. Fe-N-Al alloy films were deposited in Ar and $N_2$ mixtures at ambient temperature using Fe/Al composite targets in a two-facing-target DC sputtering system. X-ray diffraction results showed that the Fe-N-Al films were amorphous, and after annealing for 5 h both AlN and bcc-Fe/bct-$FeN_x$ phases appeared. Structure changes in the $FeN_x$ phases were explained in terms of occupied nitrogen atoms. Electron diffraction and transmission electron microscopy observations revealed that iron and iron nitride particles were randomly dispersed in annealed AlN films. The grain size of magnetic particles ranged from 5 to 20 nm in diameter depending on annealing conditions. The saturation magnetization as a function of the annealing time for the $Fe_{55}N_{20}Al_{25}$ films when annealed at 573, 773 and 873 K. At these temperatures, the amount of iron/iron nitride particles increased with increasing annealing time. An increase in the saturation magnetization is explained qualitatively in terms of the amount of such magnetic particles in the film. The resistivity increased monotonously with decreasing Fe content, being consistent with randomly dispersed iron/iron nitride particles in the AlN film. The coercive force was evaluated to be larger than $6.4{\times}10^3Am^{-1}$ (80 Oe). This large value is ascribed to a residual stress restrained in the ferromagnetic particles, which is considered to be related to the present preparation process.

• Polymer(Korea)
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• v.27 no.2
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• pp.91-97
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• 2003

The effect of fluorination of nanoscaled silicas on mechanical interfacial properties and thermal stabilities of the silica/polyurethane composites was investigated. The surface properties of the silica were studied in X-ray photoelectron spectroscopy and contact angle measurements. Their mechanical interfacial properties and thermal stabilities of the composites were characterized by tearing energy and decomposition activation energy, respectively. As experimental results, the London dispersive component of surface free energy and fluorine functional groups of silica surfaces were increased as a function of fluorination temperature resulting in improving the trearing energy ($G_{IIIC}$) of the composites. Also, the thermal stabilities of the composites were increased as the treatment temperature increases. These results could be explained that the fluorine functional groups on silica surfaces played an important role in improving the intermolecular interactions at interfaces between silicas and polyurethane matrix in a composite system.

• Journal of Digital Contents Society
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• v.3 no.2
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• pp.245-254
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• 2002

Currently, communication field for automation system can be divided by simple serial communication for communication between each internal devices and network base remote control system that is based on TCP/IP. In spite of great development of network, communication part for internal control is using simple RS232 base until present. Also, development techniques of system developed by object oriented program in modular programming techniques of each function unit. Currently, it developed by component base development technique that is parts unit of software. This is presented by the new alternative of software development techniques as techniques to composition independent operation unit including business logic and is connected to development of new system. Therefore, this research implemented internal communication Emulate in RS232C based on GUI that apply development techniques of component base. that is, I maked component to commnication control part between receiving and sending and, as composite it, Control part did to handling between send and receive data.

• Culinary science and hospitality research
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• v.24 no.1
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• pp.140-150
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• 2018

In this study, effects of microground coffee on the quality characteristics and acceptability of instant coffee with probiotics were investigated. A central composite design with two factors (roasting degree and dose of microground coffee) was used and ranges of roasting degree and dose were 30~50 (L value) and 5~10% respectively. Aroma preference, sweetness intensity, bitterness intensity, acidity intensity, body intensity and overall acceptability were evaluated as sensory characteristics and quadratic regression models of all the properties were significant. Especially in aroma preference and overall acceptability, the higher roasting degree and dose of microground coffee, the more aroma preference and overall acceptability of the coffee increased. And this results accorded with the object of this study to increase aroma preference and overall acceptability by blending microground coffee with instant coffee. On the other hand, 129 of aroma compounds were detected in instant coffee with microground coffee but 2,5-dimethyl-pyrazine, ethyl-pyrazine and furfural were significant in quadratic regression models. The optimal conditions were predicted by response surface methodology and desirability function approach and the optimal conditions of roasting degree and dose of microground coffee were 30(L value), 8.4%(w/w) respectively to maximize 2 sensory characteristics (overall preference, aroma preference) and 3 aroma components (2,5-dimethyl-pyrazine, ethyl-pyrazine, furfural).

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.465-469
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• 2008

Mobile phone becomes composite product which the high technological multimedia functions of a Digital camera, MP3, MP4, Blue-tooth, DMB over basic functions of a calling and 3M3. By the view of user, many functions give a heavy burden rather than supporting convenient function itself because it is complex for user to use it. We want to evaluate how users feel using mobile phone according to age, comparing use frequency and necessity. So survey is tried to figure out the difference between use frequency and necessity by dividing three groups into 20s and 30s and 50s. As a result, difference of use frequency and necessity for functions of mobile phone between 20s and 30s and 50s. And the other users have the difference. Consequently, mobile phone development according to age is necessary to satisfy user's desire, evaluating elements research of user preference. We hope this paper can contribute to mobile phone development as a basic guidance.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.324-330
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• 1999

$Si_3N_4$-$TiB_2$ with 2 wt% $Al_2O_3$ and 4 wt% $Y_2O_3$ additives was hot pressed in a flowing $N_2$ environment with varying $TiB_2$ content from 10 to 50 vol%. Variations of mechanical (hardness, fracture toughness, and flexual strength), and tribological properties as a function of $TiB_2$ content were investigated. As the content of $TiB_2$ increased, relative density decreased due to the chemical reaction of $TiB_2$in $N_2$ environment. The reduction of density causes mechanical properties to be degraded with an increase of $TiB_2$ in $Si_3N_4$. Tribological properties were dependent of microstructure as well as mechanical properties, however, they were degraded strongly by the chemical reaction of $Si_3N_4$-$TiB_2$ during hot pressing in $N_2$ environment. SEM and TEM observations, and X-ray diffraction analysis that the chemical reaction products at the interface are TiCN, Si, and $SiO_2$. Also, the comparison of XRD patterns of the $Si_3N_4$-40 vol% $TiB_2$ composites hot pressed at $1,750^{\circ}C$ for 1 hour between in $N_2$ and in Ar gas was made. The XRD peaks of Si and $SiO_2$ were not found in Ar, but still a weak peak of TiCN was presented.