• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.3
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• pp.93-98
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• 2005

The crystal growth of calcite at a low temperature range was carried out by the hydrothermal method using amorphous calcium carbonate which has excellent solubility in water. Amorphous calcium carbonate was prepared by the wet chemical reaction of a stoichiometric mixture of $CaCl_2\;and\;Na_2CO_3$. An important factor was the reaction temperature and time taken in preparation of the amorphous calcium carbonate. From the solubility results calculated by the weight loss method, $NH_4NO_3$ solutions were found to be the most promising solvents to grow calcite single crystals. The hydrothermal conditions for high growth rates of calcite single crystals were as follows: starting material: amorphous calcium carbonate, solvent: 0.01 m $NH_4NO_3$, temperature: $180^{\circ}C$, duration: 30 days. And properties of calcite single crystals were follows: dislocation density: $10^6{\sim}10cm^{-2}$, UV-visible transmittance: about 80% from 190 to 400 nm and birefringence: $0.17{\sim}0.18$. Also, it can be known from the FT-IR results that the absorption peak by injection of $HCO_3^-\;and\;OH^-$ ions was not shown.

• Clean Technology
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• v.20 no.4
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• pp.383-389
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• 2014

$CO_2$ absorption processes have a good potential for large scale capture of $CO_2$ but a large amount of absorbing solution has to be regenerated, undesirably increasing the consumption of energy such as sensible heat and latent heat of vaporization. In this study, a cooling crystallization process which would separate the $CO_2$-rich potassium bicarbonate crystals from $CO_2$-lean water was developed to reduce the energy penalty. Sterically hindered alkanolamine additives were used to enhance the $CO_2$ removal efficiency and their antisolvent effect on the crystallization was found in a continuous cooling crystallizer. The production yields of crystals were increased in the sequence of 2-amino-2-methyl-1-propanol (AMP) < 2-amino-2-methyl-1,3-propanediol (AMPD) < 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD), which are related to the number of hydroxyl groups in the additive molecules. Using $^{13}carbon$ nuclear magnetic resonance, the additives favored the formation of bicarbonate ions by steric hindrance effect and increased the supersaturation of $KHCO_3$. It is shown that the additives increase the mean size of crystals and crystal growth rate by increasing supersaturation. The additives are promising for enhancing the $CO_2$ removal efficiency and reducing the regeneration energy cost of $CO_2$ absorbing solution by promoting $KHCO_3$ crystallization.

• Food Science and Preservation
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• v.9 no.4
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• pp.418-424
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• 2002

This study was undertaken to develop the optimum baking formular and process in making the improved soy-wheat composite breads furtified with soy flour, which has been known for a source of biologically active phytochemicals and for more vegetable proteins as well. The effects of the addition of soy flour on a rheological properties of dough, on the sensory characteristics of breads, and on the possibilities of commercialization of these functional breads were investigated. As the added amount of soy flour increased, water absorption, development time and the weakness value of dough were increased, but dough stability were decreased in the farinograph. In the extensograph, the more soy flour was added, the less the extensibility and the resistance to extention were shown. As the amount of soy flour increased, gelatinazation point was increased in the amylograph, but the maxium viscosity was decreased. As the added amount of soy flour was increased, b value(yellowness) was obviously increased, L value(lightness) was slightly decreased. However, a value(redness) was not nearly changed in the color of cut loaves. In sensory evaluation, the more soy flour was added, the less the external, the internal characteristics and the eating qualities were shown. Accorting to the addition of soy flour, the toughness and the brittleness tended to be increased proportionally. The dough of 10% soy-wheat composite flour(SF10) was the most favorable on the baking performance.

• Food Science and Preservation
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• v.14 no.4
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• pp.369-377
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• 2007

This study investigated the effect of ginseng products on the baking properties of white breads. Flour was substituted by ginseng products (ginseng at levels 2, 4, 6, and 8%, all w/w, of flour levels). Both ginseng powder (GP) and red ginseng powder (RGP) were used. Similarly, red ginseng extract (RGE) was substituted at levels of 1, 2, 3, and 4% (all w/w) of flour. The physical properties of each dough were assessed using farinograms, extensograms, and amylograms. Water absorption increased as the proportions of ginseng products rose. The dough surface areas and R/E (resistance/extensibility) values decreased, as did peak viscosities, at the proportions of ginseng products increased. The pH values during fermentation decreased as the proportions of ginseng products increased. The fermentation power of dough with GP was lower than that of control, and higher than that of dough with RGP or RGE, but the addition of ginseng products beyond certain levels weakened the gas retention power: The specific loaf volumes of breads with 2% GP were the highest at 5.41 mL/g. In breads with RGE, the specificloaf volume increased from 5.52 mL/g to 5.82 mL/g as RGE levels rose from 0% to 4%. Hardness increased with rising GP and RGP levels in breads with GP and RGP, but decreased with RGE levels in breads with RGE. The moisture contents of breads during storage tended to be higher than control in breads with ginseng products. Lightness increased with addition of GP and decreased upon addition of RGP or RGE, while redness and yellowness increased after addition of any ginseng products. In sensory evaluation tests, the sensory scores for texture, color, mouth feel, and overall acceptability, were high, when any ginseng product (GP, RGP or RGE) was present at 2%. Of these breads, the bread with 2% RGE attained the highest sensory score.

• Food Science and Preservation
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• v.14 no.4
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• pp.337-344
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• 2007

Lentinus edodes (Shiitake mushroom) powder was added to Jeonbyeong dough in an effort to improve the quality and functional properties of the dough. The water absorption increased as the amount of L. edodes powder increased, while the time taken for gelatinization, and the valorimeter value of the final dough, both decreased. The temperature at gelatinization and the highest temperature attained during dough preparation were both similar to control values. The extensogram showed that the resistance of the dough to extension, and the maximum extensibility, both decreased with addition of L. edodes powder. The total contents of crude protein and ash increased with increasing amounts of L. edodes powder, while the dough carbohydrate levels decreased. Addition of the mushroom powder to Jeonbyeong (a kind of Korean traditional snack) decreased dough lightness, and decreased yellowness, as measured on Hunter's color scale. The hardness of Jeonbyeong was increased by adding 15% (w/v) L. edodes powder, but was decreased when 20% (w/v) L. edodes powder was used. The sensory score of Jeonbyeong containing 10% (w/v) L. edodes powder was the highest of all shack tested, in both overall quality characteristics and sensory evaluation.

• Korean Journal of Ichthyology
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• v.25 no.4
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• pp.200-207
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• 2013

We investigated developmental stages of egg and early life history of the Korean indigenous fish, Korean Chub Zacco koreanus from the South Han River in 2011 for phylogenetic study and conservation of this species. Eggs of Zacco koreanus were artificially fertilized by the dry method in the laboratory. The fertilized eggs were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk, and no oil globule and average $3.09{\pm}0.07$ mm (n=10) in diameter. The hatching of the embryo took place in about 68 hrs after fertilization under water temperature of $20.0{\sim}23.0^{\circ}C$ and the newly hatched larvae were average $10.30{\pm}0.40$ mm (n=10) in total length (TL). Six days after hatching, the larvae grew up to $16.12{\pm}0.42$ mm (n=8) in TL and york sac absorption, mouth and anus opening were shown postflexion larvae stage. 17 days after hatching, most of fin-rays appeared at $18.21{\pm}0.38$ mm (n=6) in TL and brown spot appeared on the abdomen. 27 days after hatching, the larvae were brought up to $20.01{\pm}1.12$ mm(n=5) in TL and all their fin-rays were formed. 120 days after hatching, the larvae (juvenile) were $23.29{\pm}3.12$ mm (n=10) in TL and their body shape and color pattern were similar to the adult fish.

• Journal of Plant Biology
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• v.7 no.2
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• pp.9-13
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• 1964

As to the up-lnd bamboos, I have reported, in my previous works, that Korea has two species in the genus of Pseudosasa, four in Pleioblastus, and other four in Sasa. In the present work, I dealt with Sasamorpha Purpurascens Nakai var. Borealis Nakai which proved the strongest vitality of all up-land bamboo yet found in various up-lands of Korea, and which might be most important from the utility view-point. This report is chiefly on its procreation. Sasamorpha Purpurascens Nakai var. Borealis Nakai can be found almost everywhere throughout the country, and its leaves and stems are much used in farms in various forms of manufacture. It is also welcomed as the feed for livestocks and as cover plants for aforestation, especially as the excellent means of errosion control on devastated hill sides. It is also widely accepted that it will provide, in the immediate future, abundant sources for the up-land bamboo pulp. As the first phase of my research plan on the subject, I undertook to determine the possible best way of its procreation, for which were included the experiments of inducing the growth of subterranean stems, the entire stand cutting, transplanting, reclaimed planting after burning etc. in order to observe the plant elongation, growing conditon, climatical effect etc. What has been fuond out so far given here as follows: 1) Of the various sections of the country, Mt. Odae area gives out the most excellent Sasamorpha Purpurascens Nakai var. Borealis Nakai(the leaf weight of which is 450 gr.) and Taekwanryong area comes the next class. This species can be transplanted anywhere in the South Korea. 2) The elongation of S.P. Nakai var. Borelais begins at around the middle of May and almost completely stops by the 20th of August. 3) The best studied transplanting season is supposed to be Feb. -April, for those transplanted during that period proved 100% of success. The next best transplanting season may be October. Rain fall does not have so much effect on transplanting as the growing season does. 4) In inducing the subterranean stems, the growing season can be ignored. The root expnsion is most animated during the months of April-June, the most active season for water absorption. Those stems induced during the winter proves more rapid growth. 5) The entire stand cutting shows greater growth than the reclaimed planting after burning and that, the growth is most vigorous during May-July, whereas during the hottest months of Aug-Sept. the growth shows only 5 cm. The new shoots grow slower both in the field of entire stand cutting and in the field of reclaimed planting after burning than in the otherwise fields.

• Korean Journal of Agricultural Science
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• v.24 no.2
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• pp.182-193
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• 1997

The normal cement concrete is widely used material to build the construction recently, but it has a fault to increase the dead load on account of its unit weight is large compared with strength. Therefore, many engineers are continuously searching for new materials of construction to provide greater performance at lower density. The main purpose of the work described in this paper were to establish the physical and mechanical properties of synthetic lightweight aggregate concrete using perlite on fine aggregate and expanded clay, pumice stone on coarse aggregate. The test results of this study are summarized that the water-cement ratio was shown 47% using expanded clay, 56% using pumice stone on coarse aggregate, unit weight was shown $l,622kgf/m^3$ using expanded clay, $l,596kgf/m^3$ using pumice stone on coarse aggregate, and the absorption ratio was shown same as 17%. The compressive strength was shown more than $228kgf/cm^2$, tensile and bending strength was more than $27kgf/cm^2$, $58kgf/cm^2$ at all types, and rebound number with schmidt hammer was increased with increase of compressive strength. The static modulus was $1.12{\times}10^5kgf/cm^2$ using expanded clay, $1.09{\times}10^5kgf/cm^2$ using pumice stone on coarse aggregate, and stress-strain curves were shown that increased with increase of stress, and the strain on the maximum stress was shown identical with $2.0{\times}10^{-3}$, approximately.

• Polymer(Korea)
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• v.36 no.2
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• pp.216-222
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• 2012

We synthesized microcapsule absorbent with crosslinked poly(styrene-$alt$-maleic anhydride) (PSMA) as a core and PSMA as a shell by a precipitation polymerization method for the delayed absorption of excess water in cement mortar. cPSMA-PSMAs with core-shell structure were synthesized with ratios of 1/1, 1/2 and 1/3 as core monomer mass to shell monomer mass to control shell thickness. We observed the hydrolysis of PSMA in cement-saturated aqueous solution by a FTIR spectrometer. We observed good core-shell structure microcapsules for 1/2(cPSMA #3), but observed incomplete core-shell structure for 1/1(cPSMA #2) and 1/3(cPSMA #4) of core/shell monomer ratios. The swelling ratio of cPSMA #3 in cement-saturated aqueous solution was increased until 20 min. After that it was decreased until 2 hrs swelling time, and they started to increase again. The viscosities of cement paste with cPSMA #3 microcapsules were very slowly increased until 1 hr and increased fast after 1.5 hrs. Cement mortar with 0.5 wt% cPSMA #1 having only core part showed about 5% increase in compressive strength compared to that of plain cement mortar. cPSMA #3 added cement mortar showed the highest compressive strength with 7% increase.

• Polymer(Korea)
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• v.36 no.2
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• pp.208-215
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• 2012

To study the effect of surface crosslinked layer on the crosslinked poly(sodium acrylate) (cPSA) absorbent, we synthesized several surface crosslinked cPSAs with 5, 10 and 20 g of ethylene glycol dimethacrylate (EGDMA) by an inverse emulsion polymerization method to delay the absorption of excess water in concrete. We measured the compressive and flexural strength of mortars having 0.5, 1.0 and 1.5 wt% cPSA-EGDMA. We observed the increase of compressive and flexural strength of the cPSA-EGDMA added cement mortars except for the 0.5 wt% cPSA-EGDMA (20 g) added cement mortar. 1.0 wt% cPSA-EGDMA (5 g) added cement mortar showed about 16% and 10% increased compressive and flexural strength than those of plain cement mortar. To study the effect of porosity on compressive and flexural strength, we used FE-SEM and porosimeter. FE-SEM analysis showed swollen cPSMAEGDMA (5 g) filled between calcium silicate hydrate (C-S-H) crystals. We observed the decreased porosity of the cPSA-EGDMA added cement mortars than that of plain cement mortar. 1.0 wt% cPSA-EGDMA (5 g) cement mortar showed the lowest porosity of 16.5%.