• Applied Microscopy
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• v.42 no.1
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• pp.17-26
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• 2012

Histologic and microstructural changes during the postembryonic development of the wolf spider Arctosa kwangreungensis were studied using light and scanning electron microscopy to examine the relationship between a morphological differentiation and behavioral properties. The postembryo with abdominal yolk sac was stayed inactive in the egg case because its muscular and visual systems were not fully developed to a functional level. The first instar spiderlings, developed from the postembryo by a first molting process, started to exhibit its pigmentation on their body cuticles. In particular, undifferentiated cell clusters of central nervous system (CNS) were densely distributed within the cephalothorax, and highly differentiated abdominal ganglion was observed. They had a characteristic visual system looks more like its adult counterpart, and had segmented appendages looks more like the tiny spiders containing well oriented muscular system. After 3rd instar, spiderlings grew more rapidly with accordance to their consistent growth and periodical molting processes. Thus, the relative area of CNS with respect to cephalothorax was gradually decreased, instead a pair of venom glands, musculature, and connectives occupied the residual area. It has been revealed that the early development of spider can be controled by the feeding condition of larval period, since histologic and microstructural differentiations in both appendages and optic system were completed at the second instar. In particular, behavioral properties of the wandering spiders that depend on vision and their running ability were deeply related to physiological differentiation of the microstructural development.

• Korean Journal of Food Science and Technology
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• v.47 no.3
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• pp.321-327
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• 2015

The optimal condition for preparation of powdered calcium acetate (LCCA) which has high solubility, from calcined powder (LCCP) of the littleneck clam shell by response surface methodology (RSM) was examined. Increased molar ratio of LCCP led to reduced solubility, yield, color values, and overall quality. The critical values of multiple response optimization of independent variables were 2.57 M of acetic acid and 1.57 M of LCCP. The actual values (pH 7.0, 96.1% for solubility, and 220.9% for yield) under the optimized condition were similar to the predicted values. LCCA showed strong buffering capacity between pH 4.89 and 4.92 on addition of ~2 mL of 1 N HCl. The calcium content and solubility of LCCA were 21.9-23.0 g/100 g and 96.1-100.1%, respectively. The FT-IR and XRD patterns of LCCA were identified as calcium acetate monohydrate, and FESEM images revealed an irregular and rod-like microstructure.

• The Korean Journal of Food And Nutrition
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• v.23 no.3
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• pp.405-410
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• 2010

The effect of microwave treatment on Korean ginseng was studied by measuring the changes in moisture, crude lipid, crude ash, crude protein, total dietary fiber and saponin contents, as well as changes in density, color and microstructure. Korean ginseng was treated with 100 or 200 watts of microwaves for 1 or 3 hrs, respectively, followed by drying using an oven at $60^{\circ}C$ for 96 hrs. The moisture contents decreased to 13.12~10.77% from an initial 76.26%. The amounts of lipid and ash were reduced in proportion to the time of microwave treatment and level of microwave power. The amount of protein in ginseng after microwave treatment did not significantly change. The amount of total dietary fiber increased after microwave treatment and the color of dried ginseng became dark. The amounts of ginsenoside-$Rb_1$, $Rb_2+Rb_3$, Rc, Rd, Re, Rf, $Rg_1$, $Rg_2+Rh_1$ and $Rg_3$ were reduced after treatment with 100 watts of microwave radiation for 1 and 3. The amounts of ginsenoside-$Rb_1$, Rd, Re, Rf, $Rg_1$, $Rg_2+Rh_1$ and $Rg_3$ after treatment with 200 watts of microwave radiation for 1 and 3 hr also reduced. On the other hand, the amounts of ginsenoside-$Rb_2+Rb_3$ and Rc after treatment of ginseng with 200 watts of microwave radiation for 1 and 3 hrs were increased.

• Journal of Biomedical Engineering Research
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• v.24 no.3
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• pp.203-208
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• 2003

The effect of indium on the microstructure and hardness of a Au-Pt-Cu ternary alloy was investigated using optical microscopy, differential scanning calorimeter, scanning electron microscopy x-ray diffractometry, electron probe microanalizer and vickers hardness tester. A hardness of the solution floated Au-Pt-Cu-0.5In quarternary alloy with 0.5 wt.% was reached a maximum value (162 Hv) in 30 min at 550$^{\circ}C$ in the range of 150 to 950$^{\circ}C$ but that of the alloy was rapidly increased until 30 min with increasing aging time at 550$^{\circ}C$ and after that was remained almost constant value. Also, the microhardness of the matrix Au-Pt-Cu ternary alloy aged at 550$^{\circ}C$ for 30 min was continuously increased with indium contents and the grain size of Au-Pt-Cu ternary alloy decreased as increased indium contents. Analyses of EPMA and XRD revealed that the matrix Au-Pt-Cu-In quarternary alloy is composed of fcc structure and intermetallic InPt$_3$ precipitate with Ll$_2$ structure. Based on this investigation, it can be concluded that an increase in microhardness of Au-Pt-Cu-In quarternary alloy is due to precipitation hardening InPt$_3$ and grain size refinement.

• Journal of the Korean institute of surface engineering
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• v.38 no.2
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• pp.65-68
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• 2005

The effect of crystal orientation and microstructure on the mechanical properties of $TaN_x$ was investigated. $TaN_x$ films were grown on $SiO_2$ substrates by ultrahigh vacuum unbalanced magnetron sputter deposition in mixed $Ar/N_2$ discharges at 20 mTorr (2.67 Pa) and at $350^{\circ}C$. Unlike the Ti-N system, in which TiN is the terminal phase, a large number of N-rich phases in the Ta-N system could lead to layers which had nano-sized lamella structure of coherent cubic and hexagonal phases, with a correct choice of nitrogen fraction in the sputtering mixture and ion irradiation energy during growth. The preferred orientations and the micro-structure of $TaN_x$ layers were controlled by varing incident ion energy $E_i\;(=30eV\~50eV)$ and nitrogen fractions $f_{N2}\;(=0.1\~0.15)$. $TaN_x$ layers were grown on (0002)-Ti underlayer as a crystallographic template in order to relieve the stress on the films. The structure of the $TaN_x$ film transformed from Bl-NaCl $\delta-TaN_x$ to lamellar structured Bl-NaCl $\delta-TaN_x$ + hexagonal $\varepsilon-TaN_x$ or Bl-NaCl $\delta-TaN_x$ + hexagonal $\gamma-TaN_x$ with increasing the ion energy at the same nitrogen fraction $f_{N2}$. The hardness of the films also increased by the structural change. At the nitrogen fraction of $0.1\~0.125$, the structure of the $TaN_x$ films was changed from $\delta-TaN_x\;+\;\varepsilon-TaN_x\;to\;\delta-TaN_x\;+\;\gamma-TaN_x$ with increasing the ion energy. However, at the nitrogen fraction of 0.15 the film structure did not change from $\delta-TaN_x\;+\;\varepsilon-TaN_x$ over the whole range of the applied ion energy. The hardness increased significantly from 21.1 GPa to 45.5 GPa with increasing the ion energy.

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.207-212
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• 2002

This study was to examine the characteristics in the texture of acorn Mooks (acorn starch jelly) with different conditions to prepare acorn starch. By texture profile analysis, hardness and chewiness with 50% deformation were increased with increasing soaking days. Hardness of acorn Mook, measured by texture analyzer, showed significantly difference between the samples, and was closely related to the content of non-starchy substances and their intrinsic viscosity. The observation of microstructure through a scanning electron microscope (SEM) showed that acorn Mook showed finer and more fibrous structure than control(0-0), sample without soaking of acorn and sediments. Sensory characteristics of acorn Mook were affected by soaking treatment. The result of acceptance test on acorn Mooks indicated that the color and hardness increased with the increase of soaking days of acorn nuts and soaking times of sediments. There was a little difference between the samples in astringency taste. Their overall acceptability also increased except for 4-2 sample (i.e., soaking of acorn, 4 days; soaking of sediments, 2 times) and 4-3 sample (i.e., soaking of acorn nuts, 4 days; soaking of sediments, 3 times). As the results, the color, light brown, and the taste, a little astringency with consistency, were important factors of acorn Mook.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.604-609
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• 2000

This study was carried out to investigate the possibilities of adopting xanthangum, guargum and ${\kappa}-carrageenan$ as cryprotectant by examining the rheological and structural properties of dough. Results of farinography showed that water absorption, development time and mechanical tolerance index in dough with the gums increased more than those of the control. It was also found that resistance in dough with the gums increased greatly, but extensibilities were similar to that of the control, resulting in increasing R/E values in the dough with the gums through extensograph. According to amylogram, gelatinization temperature of dough was $59.5^{circ}C$ and those of the dough with the gums were $58^{circ}C$. Even though maximum viscosity of the dough was 550 B.U in the control, those were 690 B.U, 780 B.U and 760 B.U in the dough with xanthangum, guargum, and ${\kappa}-carrageenan$, respectively. The control deeply increased the pH during frozen storage but the addition of ${\kappa}-carrageenan$ and xanthangum increased the pH slightly. The dough with the gums had more stable spaces than control in the microstructure through SEM.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.799-805
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• 2001

Two commercial alumina powders having different particle size of $0.5{\mu}m$ and 3${\mu}$m were presintered at 1120$^{\circ}$C for 2h and then lanthanum aluminosilicate glass was infiltrated at 1100$^{\circ}$C for up to 4h to obtain the densified glass-alumina composites. The effect of alumina particle size on packing factor, microstructure, wetting, porosity and pore size, and mechanical properties of the composite was investigated. The optimum mechanical properties and compaction behavior were observed for the 3${\mu}$m alumina particle dispersed composite. The 3${\mu}$m alumina particle size and distribution for he preform were within 0.1 to 48${\mu}$m and bimodal and random orientation. The strength and the fracture toughness of the composite having 3${\mu}$m alumina particles were 519MPa and $4.5MPa{\cdot}m^{1/2}$, respectively.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.853-859
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• 2001

The dispersion stability of nano $Y_2O_3-CeO_2$ system was investigated using colloid surface chemistry. Green body of $Y_2O_3$ doped $CeO_2$ was prepared by slip casting in and aqueous system. The dispersion stability of suspension between powders and organic additive was accomplished through electrokinetic behavior of suspension, which was done by ESA apparatus. The dynamic mobility of particles was enhanced when the anionic dispersant of the amount of 1wt% was added. The dissolution of $Y^{3+}$ ion in suspension occurred in the acidic region so that pH value in slurries did not move to below 7.0. In the $CeO_2-Y_2O_3$ system, optimal preparation of suspension was made after adding the anionic dispersant as the amount of 1wt% and pH value of 11.0, and then slip-cast and sintered at 1400$^{\circ}$C, 2 hrs. It appeared relative density of >98% and homogeneous distribution of Y element in depth direction as well as in the microstructure of surface.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.943-948
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• 2003

The microstructure and electrical characteristics of Zn-Pr-Co-Cr-Dy oxides-based varistors were investigated with Dy$_2$ $O_3$ content in the range of 0.0∼2.0 ㏖%. As Dy$_2$ $O_3$ content is increased, the average grain size was decreased in the range of 18.2∼4.6 $\mu\textrm{m}$ and the ceramic density was decreased in the range of 5.49∼4.64 g/㎤. The incorporation of Dy$_2$ $O_3$ markedly enhanced the nonlinear properties of varistors more than 9 times in nonlinear exponent, compared with the varistor without Dy$_2$ $O_3$ The varistor with 0.5∼1.0 ㏖% Dy$_2$ $O_3$ exhibited the high nonlinearity, in which the nonlinear exponent is above 55 and the leakage current is below 1.0 ${\mu}\textrm{A}$. The donor concentration and the density of interface states were decreased in the range of (4.66∼0.25)${\times}$10$\^$18//㎤ and (5.70∼1.39)${\times}$10$\^$12//$\textrm{cm}^2$, respectively, with increasing Dy$_2$ $O_3$ content. The minimum dielectric dissipation factor of 0.0023 was obtained for 0.5 ㏖% Dy$_2$ $O_3$, but further addition of Dy$_2$ $O_3$ increased it.