• The Korean Journal of Rheology
• /
• v.10 no.4
• /
• pp.195-201
• /
• 1998

We have studied the rheological and electrical properties of two types of electrorheological (ER) fluids based on semi-conductive polymers (poly(p-phenylene) and polyaniline). These semi-conductive polymer-based suspensions showed a dramatic increase in viscosity on the application of the static electric field due to the large value of conductivity ratio between particle and medium. The dynamic yield stresses of these ER suspensions exhibited a quadratic dependence on electric field strength at low electric fields and a linear one for high fields. They showed a maximum and then decreased with increasing bulk conductivity of particles. These yield stress behaviors under the static electric field were found to be closely related to the dielectric properties, which is in accord with Maxwell-Wagner interfacial polarization induced by the conductivity effects. In order to achieve better understanding of interfacial polarization effect on ER response and to improve the stability of ER suspension, different kinds of surfactants were employed for controlling the ER activity as well as for enhancing the colloidal stability of suspensions.

• Journal of Plant Biotechnology
• /
• v.32 no.1
• /
• pp.51-55
• /
• 2005

Chinese leymus (Leymus chinensis Trin.) is a perennial grass that is widely distributed at high pH sodic and arid soil in the northeastern Asia. An efficient regeneration system was established through somatic embryogenesis of mature seeds to understand its high adaptability to harsh environmental conditions on the basis of molecular biology. The calli were efficiently induced (about $70\%$) from mature seeds on MS medium supplemented with $1.5\;\cal{mg/L}$ 2,4-D. Somatic embryos were formed from the surface of embryogenic callus on MS medium supplemented with $2.0\;\cal{mg/L}\;kinetin\;and\;0.5\;\cal{mg/L}$ NAA after 3 weeks of culture. Roots were induced from the shoot when transferred to MS medium without plant growth regulator for 1 week. Plant regeneration rate was $36\%$ and regenerated plantlets were grown to normal mature plants in pot. An efficient plant regeneration system in this study will be useful for molecular breeding of L. chinensis.

• Korean Journal of Food Science and Technology
• /
• v.36 no.3
• /
• pp.490-500
• /
• 2004

Brown rice grains were coated by spraying aqueous protein solution extracted from rice bran using 10% ethanol, and dried at room temperature. Coating procedure was repeated 1-5 times to determine effect of repeated coating, Quality changes in coated brown rice grains were observed during 8 weeks storage. Most coated rice grains gave lower peroxide and acid values, which indicate antioxidative effects of coating. Lipase and lipoxygenase activities generally decreased in grains coated more than three times. Microscopic images of whole kernel and longitudinal section revealed cracking on all brown rice grains including control, and hydration rate constants were not significantly different among treated grains. Compared to non-coated brown rice grains, those coated more than three times, after 8 week storage, showed better quality retention observed in (meaning not clear) higher water-binding capacity, lower gel consistency decrease, less browning, and better textural properties in cooked rice, resulting in better sensory quality.

• Korean Journal of Environmental Agriculture
• /
• v.4 no.2
• /
• pp.102-107
• /
• 1985

A pot experiment was conducted to find out the effects of water management, slaked lime and wollastonite on growth and Cu uptake of rice at Cu added soil. The soil was adjusted to 0, 50, 100 and 200 ppm concentration of Cu. The application amount of slaked lime was the lime requirement plus 150 ㎏/l0a and wollastonite 200 ㎏/10a, respectively. The copper concentration in soil which reduced yield significantly was 133.1 ppm for submersion and 136.8 ppm for intermittent irrigation. The application of lime and wollastonite reduced Cu content in brown rice as well as increased rice yields compared to that of no lime. The copper content in plant was increased with increasing soil Cu concentration, however, reduced with submersion and application of slaked lime, and increased with increasing the ratio of Cu/Ca+Mg equivalent in soil.

• Proceedings of the Korea Technology Innovation Society Conference
• /
• 2004.11a
• /
• pp.101-113
• /
• 2004

본 연구는 기술혁신파급경로를 결정하는 국가 간 무역역할에 대한 실증적인 분석을 목적으로 한다 이 연구목적을 위하여, 최근 자료인 1980년부터 2003년까지 15개 OECD국가를 대상으로 자국의 기술혁신을 결정하는 중요한 변수로 알려진 자국 R&D축적 및 무역대상국의 R&D축적자료를 구축하였으며, 이를 무역지수인 쌍방간에 수출 및 수입량을 경제규모로 나눈 가중지수를 이용하여 유입된 R&D축적량을 구축하였다. 또한 대상변수들의 기술혁신파급역할에 대하여 최근 논의되고 있는 비정상적 패널기법을 이용하여 분석하였다. 최근 제안되고 있는 비정상적 패널기법을 이용하여 국제 간에 기술혁신파급경로를 분석한 결과를 간단하게 요약하면, 다음과 같다. 첫째, 분석대상변수들은 비정상성을 갖는 것으로 나타났다. 둘째, 그러나 장기적으로 분석대상변수들이 서로 균형상태를 나타내는 공적분관계에 있음을 알 수 있었다. 셋째, 국가 간에 기술혁신파급경로의 방향과 정도를 파악하기 위하여 패널 공적분계수를 추정하였으나, 설정함수형태에 따라서 여러 가지 상반된 실증결과가 나타났다. 따라서 기존 연구Coe et al., 1995, Keller, 1998, Kao, et al., 1999 그리고 Funk, 2001]의 분석결과 및 그 시사점들이 서로 다른 이유는 분석대상변수들의 선택차이뿐만 아니라, 기술혁신경로에 대한 설정함수형태에 따라서 서로 다른 분석결과가 나타날 수 있는 가능성을 보여준다. 본 연구에서 나타난 분석결과의 시사점을 보면, 국가 간에 기술혁신파급경로분석은 기술혁신파급을 결정하는 매개변수선정도 중요하지만, 결정된 설명변수들 사이에 어떤 기술혁신파급에 관한 연관관계가 존재하는지에 대한 실증분석 즉 파급경로분석도 매우 중요함을 보여준다. 이러한 파급경로분석에는 기존의 선형가정뿐만 아니라 비선형가정을 이용한 기술파급경로분석을 통한 시사점제안이 요구된다.관적인 시스템을 제공하는 것이다.가 생성된다. $M_{C}$에 CaC $l_2$를 첨가한 경우 $M_{C}$는 완전히 $M_{Cl}$ 로 전이를 하였다. $M_{Cl}$ 에 CaC $l_2$를 첨가하였을 경우에는 아무런 수화물의 변화는 발생하지 않았다. 따라서 CaS $O_4$.2$H_2O$를 CaC $O_3$및 CaC $l_2$와 반응시켰을 때의 AFm상의 안정성 순서는 $M_{S}$ < $M_{C}$< $M_{Cl}$ 로 된다.phy. Finally, Regional Development and Regional Environmental Problems were highly correlated with accommodators.젼 공정을 거쳐 제조된다는 점을 고려할 때 이용가능한 에너지 함량계산에 직접 활용될 수는 없을 것이다.총단백질 및 AST에서 시간경과에 따른 삼투압 조절 능력에 문제가 있는 것으로 보여진다.c}C$에서 5시간 가열조리 후 잔존율은 각각 84.7% 및 73.3%였고, 질소가스 통기하에서는 잔존율이 88.9% 및 81.8%로 더욱 안정하였다.8% 및 12.44%, 201일 이상의 경우 13.17% 및 11.30%로 201일 이상의 유기의 경우에만 대조구와 삭제 구간에 유의적인(p<0.05) 차이를 나타내었다.는 담수(淡水)에서 10%o의 해수(海水)로 이주된지 14일(日) 이후에 신장(腎臟)에서 수축된 것으로 나타났다. 30%o의 해수(海水)에 적응(適應)된 틸라피아의 평균 신사구체(腎絲球體)의 면적은 담수(淡水)에 적응된 개체의 면적보다 유의성

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.3
• /
• pp.302-308
• /
• 2005

Nitrate is one of common contaminants frequently found in the bank filtrate. Biological autotrophic denitrification into permeable reactive barrier(PRB) system to reduce nitrate concentration in bank filtrate was implanted. The objectives of research are to investigate effect of inoculation, to evaluate alternative alkalinity sources, and to determine effect of hydraulic characteristics, such as retention time, flow rate on the performance of semi-pilot PRB system. Semi-pilot scale biological PRB system was installed using elemental sulfur and limestone/oyster shell as reactive materials near Nakdong River in Kyoungnam province, Korea. Nitrate concentration in bank filtrate was reduced by indigenous microorganisms in oyster shell as welt as by inoculating microorganisms isolated from the sludge of an anaerobic digester in a wastewater treatment plant. Oyster shell as well as limestone can be used as an alkalinity source. However, oyster shell resulted in suspended solids of effluent. As the flow rate in the system increased from 66 to 132 mL/min and accordingly the residence time decreased from 15 to 7.5 hours, nitrate concentration in effluent increased and nitrate removal efficiencies decreased from 75 to 58% at the fixed thickness of 80 cm of PRB.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.24 no.6
• /
• pp.268-273
• /
• 2014

$Y_2O_3$ ceramic specimens were fabricated from the granular powder, obtained by spray drying process from the slurry. The slurry was prepared by mixing PVA binder, NaOH for Ph control, PEG and $Y_2O_3$ powder. The $Y_2O_3$ specimen was shaped in size of ${\phi}14mm$ and then sintered at $1650^{\circ}C$. The characteristics, microstructure, densities and plasma resistance of the $Y_2O_3$ specimens were investigated with the function of forming pressure and sintering time. $Y_2O_3$ specimens were exposed under the $CHF_3/O_2/Ar$ plasma, the dry etching treatment of specimens was carried out by the physical reaction etching of $Ar^+$ ion beam and the chemical reaction etching of $F^-$ ion decomposed from $CHF_3$. With increasing sintering time, $Y_2O_3$ specimens showed relatively high density and strong resistance in plasma etching test.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.12
• /
• pp.1712-1717
• /
• 2009

Capsaicin has been shown to affect lipid metabolism. However, it is currently not known whether capsaicin would lower the intestinal absorption of cholesterol. Thus, this study was conducted to investigate the effect of intraduodenally infused capsaicin on the lymphatic absorption of cholesterol and lipids in rats. Male Sprague-Dawley rats weighing 300-350 g were starved for 16 hr and the mesenteric lymph duct was cannulated. Each rat was infused at 3.0 mL/hr for 8 hr via the duodenal catheter with a lipid emulsion, which contained 33.3 kBq [$^{14}C$]-cholesterol, 20.7 μmol cholesterol, 452 μmol triolein, 3.1 μmol $\alpha$-tocopherol, and 396.0 μmol Na-taurocholate without (control) or with 5.0 mg capsaicin in 24 mL PBS buffer (pH 6.4). Simultaneously, lymph was collected hourly for 8 hr. There was no significant difference in lymph flow between the groups. However, the lymphatic absorption of 14C-cholesterol for 8 hr was significantly lower in rats infused with capsaicin than in those infused with no capsaicin. Also, the output of oleic acid for 8 hr was significantly decreased by capsaicin. However, the intestinal absorption of $\alpha$-tocopherol did not differ between the groups. The results indicate that the luminal infusion of capsaicin inhibits the intestinal absorption of cholesterol and lipids in rats.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.10 no.1
• /
• pp.17-22
• /
• 1977

In the present paper, the effect of sodium sulfite treatment on tile inhibition of browning reactions occurring in the storage of dried oyster was tested and the supplementary effect of antioxidantsaddedwasalsomentioned. Dried oysters treated with sodium sulfite solutions as described in the previous paper(Lee and Choi, 1977) were stored in the bottles with silica gel bags at room temperature with or without the application of antioxidants. The ethanol solution of an antioxidant mixture(BHA, BHT, plus, synergists) was sprayed on the surface of cooked oyster before drying. The density of brown pigment was determined spectrophotometrically by measuring the absorbance at 420 and 440 nm of both fractions of pigment extract, namely chloroform-methanol and water soluble fractions, which represent the brown color developed by fat oxidation and Maillard reactions respectively. TBA value was also measured for the oxidative rancidity in oysters during the storage. It appeared from the results that the 0.5 M sodium sulfite-60minute treated samples showed better effect after 150 day storage at room temperature. Controlling tile pH of treating solutions, did not reveal so much different in inhibitory effect in the aspect of color but a more reduction of tyrosine and reducing sugar was resulted with acidic solution than with alkaline solution. The development of brown color in dried oyster seemed to be leaded rather by the oxidative rancidity of lipids than sugar-amino reactions particularly in a long-term storage since the browning of chloroform-methanol fraction progressed more rapidly than of water. soluble fraction. The application of antioxidant, therefore, could largely retard the browning of the product as appeared in the results that sodium sulfite treated oyster with addition of antioxidant kept the best color during the storage.

• Korean Journal of Ecology and Environment
• /
• v.33 no.4 s.92
• /
• pp.358-365
• /
• 2000

To evaluate the influences of stocking and removal of silver carp on plankton communities and physicochemical parameters, fish biomanipulation was conducted in six enclosures constructed on the coast of a hypertrophic lake during the summer of 1997. Of these, three enclosures were established for the fish-stocking experiment; one fishless enclosure used as a control and two enclosures with high and low densities of fish. The other three enclosures for the fish-removal experiment were prepared in an entirely converse process compared to that for fish stocking. The results of randomized intervention analysis (${\alpha}=0.05$) showed significant changes in several physicochemical parameters and plankton communities after fish stocking and removal. Fish stocking decreased water transparency, DO, pH and chi-a (> $40\;{\mu}m$), while increasing the concentration of nitrogen and chi-a (<$2\;{\mu}m$). However, water transparency did not increase by fish removal. Small plankton communities, such as picocyanobacteria, eukaryotic picoplankton and ciliates (<$2\;{\mu}m$) showed significant reciprocal changes after both fish treatments: increase by the presence of fish and decrease by the absence of fish. No count of large sized phytoplankton and zooplankton showed significant change in the presence of fish, while large zooplankton, Diaphanosoma, Cyclopida and nauplii were significantly increased by fish removal. Although the frequent heavy-winds and endless supply of phosphorus from the lake sediment strongly disturbed the fish behavior and enclosure management, the stocking and removal of silver carp showed an obvious reciprocal influences on plankton communities and its physico-chemical parameters in a shallow-hypertrophic lake.