• Journal of Sericultural and Entomological Science
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• v.48 no.1
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• pp.11-15
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• 2006

Antheraea yamamai silk fibroin powder was prepared by treatment with HCl. The prepared A. yamamai fibroin hydrolysate was characterized by gel filtration chromatography, amino acid analysis, X-ray diffractometry, circular dichroism analysis, differential thermal analysis, and thermogravimetry. The average molecular weight of A. yamamai powder was about 430 and the major amino acids composed of the powder were Ala and Ser. According to XRD analysis, A. yamamai silk powder showed sharp diffraction peaks at $2{\theta}=20.34^{\circ}\;and\;31.5^{\circ}$. CD spectrum showed a peak around 220 nm and a should 215 nm, assigned to ${\alpha}-helix\;and\;{\beta}-sheet$ structure, respectively. DSC and TGA showed that the maximum degradation temperature of powder was around $250{\sim}270^{\circ}C$. Moreover, no harmful heavy metal was contained in the A. yamamai silk fibroin hydrolysate.

• Food Science and Preservation
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• v.13 no.3
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• pp.382-388
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• 2006

Physicochemical properties of chufa starch were investigated The result are summarized as follow: Moisture content crude protein and crude fat were 10.10%, 0.31% and 0.41,% respectively. Amylose content of chufa starch was 41.6% and blue value was 0.49. Lightness and whiteness of chufa starch was 96.36 and 92.23 of Hunter's color value. In iodine reaction, maximum absorbance wavelength (${\lambda}max$) was 628 nm. Water binding capacity was 83% and swelling power and solubility of chufa starch were increased slowly to $60^{\circ}C$, but increased rapidly after $60^{\circ}C$. Scanning election microscope(SEM) showed that granule type of chufa starch was round or elliptic type, and average granule size was $10{\mu}m$. The results by differential scanning calorimetry(DSC) revealed that gelatinization patterns were similar to those of potato or rice starch. In rapid viscoanalyzer(RVA) examination, pasting temperature was $79.95^{\circ}C$ and peak viscosity of chufa starch was 385.08.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.135-141
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• 2013

Mechanical alloying was carried out to produce $CrSi_2$ thermoelectric compound using a mixture of elemental $Cr_{33}Si_{67}$ powders. An optimal milling and heat treatment conditions to obtain the single phase of $CrSi_2$ compound with fine microstructure were investigated by X-ray diffraction and differential scanning calorimetry measurement. $CrSi_2$ intermetallic compound with a grain size of 70 nm could be obtained by MA of $Cr_{33}Si_{67}$ powders for 70 hours and subsequently annealed at $650^{\circ}C$. Consolidation of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies at $600{\sim}1000^{\circ}C$ under 60 MPa. The shrinkage of MA samples during SPS consolidation process increased gradually with increasing temperature up to $1000^{\circ}C$ and relatively significant at about $600^{\circ}C$. We tend to believe that these behaviors are deeply related to form a $CrSi_2$ compound during heating process, as can be realized from the DSC measurement. Electrical conductivity and Seebeck coefficient of sintered bodies were measured up to $900^{\circ}C$. Seebeck coefficient and power factor of $Cr_{33}Si_{67}$ compact prepared by MA and SPS at $1000^{\circ}C$ showed the maximum value of $125{\mu}V/K$ at $400^{\circ}C$ and $4.3{\times}10^{-4}W/mK^2$ at $350^{\circ}C$, respectively.

• Korean Journal of Ichthyology
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• v.30 no.1
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• pp.36-45
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• 2018

The temporal and depth-related variations in the species composition and abundance of demersal fish assemblage were studied in the coastal waters off Hupo, East Sea. Fish samples were collected seasonally between 2011 and 2017 at two stations of study area using trammel net and bottom gill net. In total, 46 fish species belonging to 17 families were collected during study period, with 36 and 22 species occurring in depths of ~80 m (site A) and ~140 m (site B), respectively. Glyptocephalus stelleri, Cleisthenes pinetorum and Gymnocanthus herzensteini were abundant at shallower site, and Dasycottus setiger at deeper site. The number of species, abundance, biomass and diversity fluctuated with water depth, but not temporally (both seasonally and annually). Analysis of similarity (ANOSIM) revealed that the fish assemblage structures were significantly different with water depth, but not by year or season. Non-metric multidimensional scaling (MDS) ordination plot emphasized visually in spatial difference of fish assemblages, and it was due to differential contributions of dominant species in relation to water depth and temperature.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.453-460
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• 2004

To prevent penetration of rainwater into the landfill site is the main purpose of the final cover in landfill sites. Conventional designs of landfill covers uses geotextiles such as geomembrane and GCL, and clay liners to lower the permeability of final covers of landfill sites. However, differential settlement and the variation of temperature in landfill sites cause the development of cracks or structural damage inside the final cover and it is also difficult to obtain clay - the main material of the compacted clay liner in Korea. Thus the former final cover system that suggests geomembrane and GCL or compacted clay liner has several limitations. Therefore, an alternative method is necessary and one of them is the application of SRSL(self-Recovering Sustainable Liner) material. SRSL is two different layers consist of individual materials that react with each other and form precipitates, and with this process lowers the permeability of the landfill final cover. SRSL generally is made up of two layers, so that when a internal crack occurs the reactants of the two layers migrate towards the crack and heal it by forming another liner. In this study the applicability of SRSL material for landfill final cover was examined by performing; (1) jar test to verify the formation of precipitate in the mixture of each reactants, (2) falling head test considering the field stress in order to confirm the decrease of permeability or prove that the hydraulic condctivity is lower than the regulations, (3) compression tests to judge weather if the strength satisfies the restricts for landfills, (4) freeze/thaw test to check the applicability of SRSL for domestic climate. In addition, the application of waste materials in the environmental and economical aspect was inspected, and finally the possibility of secondary contamination due to the waste materials was examined by performing elution tests.

• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.698-705
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• 2015

Two series of symmetric dimesogenic compounds containing a butylene or 1-methylbutylene spacer as a flexible group were synthesized. The mesogenic groups of synthesized compounds consist of an azobenzene group with a terminal substituent. Chemical structures as well as, thermal, mesomorphic, and photochemical properties of the synthesized compounds were investigated using FT-IR, $^1H-NMR$, differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and UV-visible spectrometry. P-H, P-F, and $P-OC_6H_{13}$ showed monotropic liquid crystal phases, whereas the others showed enantiotropic liquid crystal phases. Compounds with butylene group as a flexible spacer exhibited wider mesophase temperature ranges and higher thermal transition temperatures than compounds containing a 1-methylbutylene group. Compounds with a high absolute value of the Hammett substituent constant exhibited high thermal transition temperatures and improved stability in the liquid crystal phase. Furthermore, in the absence or presence of UV light illumination, terminal substituents of the azomesogenic group were important factors in deciding the maximum absorbance wavelength (${\lambda}_{max}$) and the rate of photoisomerization (K).

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.721-727
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• 2002

In order to overcome trade-off among compositions, process and properties of the glasses with high PbO-base composition for PDP Rib, we studied glass crystallization and crystallization kinetics by Differential Thermal Analysis(DTA). Glass powder was obtained through melting/cooling/grinding, with 3 wt%TiO2 addition for the crystal nucleation and growth in $62PbO-19B_2O_3-10SiO_2-9(Al_2O_3-K_2O-BaO-ZnO)$(in wt%) composition glass. This powder was heat-treated for 1 to 10 h at $445^{\circ}C$ for nucleation. DTA measurements were performed to obtain the crystallization peak with $5∼25^{\circ}C/min$ heating rates. DTA crystallization peak temperature increased with increasing the heating rate and decreased with increasing the heating time. Because the Avrami parameter (n) was approximately 1, the surface crystallization occurred. The maximum nucleation time was 2 h.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.183-190
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• 2012

Conventional physical activity monitoring systems, which use accelerometers, global positioning system (GPS), heartbeats, or body temperature information, showed limited performances due to their own restrictions on measurement environment and measurable activity types. To overcome these limitations, we developed a portable exercise analysis system that can analyze aerobic exercises as well as isotonic exercises. For bioelectric signal acquisition during exercise, waist belt with two body contact electrodes was used. For exercise analysis, the measured signals were firstly divided into two signal groups with different frequency ranges which can represent respiration related signal and muscular motion related signal, respectively. After then, power values, differential of power values, and median frequency values were selected for feature values. Selected features were used as inputs of support vector machine (SVM) to classify the exercise types. For verification of statistical significance, ANOVA and multiple comparison test were performed. The experimental results showed 100% accuracy for classification of aerobic exercise and isotonic resistance exercise. Also, classification of aerobic exercise, isotonic resistance exercise, and hybrid types of exercise revealed 92.7% of accuracy.

• Polymer(Korea)
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• v.24 no.6
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• pp.737-743
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• 2000

Polyquinonediimines (PQDI) which have stable structure on heat and contains mono-azobenzene in the side chain were synthesized by means of condensation polymerization under TiCl$_4$. The synthesized monomers and polymers were identified by FT-IR, $^1$H-NMR, and elementary analysis. Especially, PQDI was comfirmed by the double-bonding peak of >C=N appeared near 1625 $cm^{-1}$ / by means of FT-IR spectrum. PQDI containing mono-azobenzene group in both side chains wat not soluble in non-polar solvents at all but partially soluble in the polar solvents having small dielectric constant, and dissolved in the strong acid such as sulfuric acid and $CH_3$SO$_3$H. Molecular weight distribution of PQDI measured by GPC showed 1.74. It was confirmed through X-ray diffraction analysis that the polymer was partially crystalline at the low angle region, but amorphous after heat treatment at 1$25^{\circ}C$. The glass transition temperature (T$_{g}$ ) of synthesized polymer was measured as 1$25^{\circ}C$ by differential scanning calorimetry. The SHG value for $\chi$$^{(2)}$ after poling at 1$25^{\circ}C$ was 8.6 pm/V (λ=1.542 ${\mu}{\textrm}{m}$). The SHG value slowly decreased with time from the start but appeared temporal stability after 100 hours.

• Membrane Journal
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• v.21 no.3
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• pp.222-228
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• 2011

Poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer was synthesized via atom transfer radical polymerization (ATRP) and used as an electrolyte for electrochromic device. Plasticized polymer electrolytes were prepared by the introduction of propylene carbonate (PC)/ethylene carbonate (EC) mixture as a plasticizer. The effect of salt was systematically investigated using lithium tetrafluoroborate ($LiBF_4$), lithium perchlorate ($LiClO_4$), lithium iodide (LiI) and lithium bistrifluoromethanesulfonimide (LiTFSI). Wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) measurements showed that the structure and glass transition temperature ($T_g$) of polymer electrolytes were changed due to the coordinative interactions between the ether oxygens of POEM and the lithium salts, as supported by FT-IR spectroscopy. Transmission electron microscopy (TEM) showed that the microphase-separated structure of PVC-g-POEM was not greatly disrupted by the introduction of PC/EC and lithium salt. The plasticized polymer electrolyte was applied to the electrochromic device employing poly(3-hexylthiophene) (P3HT) conducting polymer.