• Korean Journal of Environmental Agriculture
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• v.18 no.4
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• pp.361-365
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• 1999

This atudy was conducted to determine the growth characteristics and photosynthesis of soybean (Glycine max L. cv. Keumjongkongl) 30 day old seedling to 100mM NaCl concentration containing 1/2 Hoagland`s nutrient solution in sand culture. The nodule formation of root is not found perfectly with NaCl stress. The leaf dry matter weight (g/plant) of stressed plant is more reduction in 77% to control than any other characters. The water content (%) is tend to increase but water potential (MPa) is tend to decrease at NaCl stress. The chlorophyll content (SPAD) is tend to increase at growing leaf age of control but decrease at NaCl stress. The photosynthesis, stomatal conductance and transpiration are tend to decrease sharply at NaCl stress.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.758-762
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• 1998

Electrical conduction property of insulator surface is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the materials to be used for outdoor insulator such as porcelain, EPDM, silicone rubber was discussed by measuring properties of average leakage current and scintillation discharge pulses under salt fog conditions. The fog was applied by nozzle in chamber and fogging fluids were deionized distilled water, 0.5wt% NaCI solution and 2wt% NaCl solution. The average leakage current showed linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage were much different to those in case of dry and clean condition with 2wt% salt fog. In case of slat fog pollution condition, the leakage current was increased above critical voltage. the scintillation discharges were also activated at the level. The leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.7
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• pp.929-934
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• 2001

The physiological role of brain somatostatin in the central regulation of feed intake in sheep was investigated through a continuous intracerebroventricular (ICV) infusion of somatostastin 1-28 (SRIF) at a small dose of $5{\mu}g/0.2ml/hr$ for 98.5 hours from day 1 to day 5. Sheep (n=5) were fed for 2 hours once a day, and water and 0.5 M NaCI solution were given ad libitum. Feed, water and salt intake were measured during ICV infusion of artificial cerebrospinal fluid (CSF) and SRIF. The feed intake during SRIF infusion on days 2 to 5 increased significantly compared to that during CSF infusion. Water intake, when compared to that during CSF infusion, only increased significantly on day 4. NaCI intake during SRIF infusion was not different from that during CSF infusion. Mean arterial blood pressure (MAP) and heart rate during SRIF infusion were not different from those during CSF infusion. The plasma concentrations of Na, K, Cl, osmolality and total protein during SRIF infusion were also not different from those values during CSF infusion.There are two possible mechanisms, that is, the suppression of brain SRIF on feed suppressing hormones and the direct actions on brain mechanisms controlling feed intake, explaining how SRIF works in the brain to bring about increases in feed intake in sheep fed on hay. The results indicate that brain SRIF increases feed intake in sheep fed on hay.

• YAKHAK HOEJI
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• v.36 no.6
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• pp.538-547
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• 1992

Optimal synthetic condition of barium sulfate were investigated from the viewpoint of yield and bulkiness according to a randomized complete block design proposed by G.E.P. Box and K.B. Wilson. Barium chloride and magnesium sulfate were utilized as reactants in order to prepare barium sulfate in this study. It was found that optimum temperature range of reactant solutions was $60{\sim}100^{\circ}C$ and the optimum concentration range of the reactant solutions was $10{\sim}17.3%$ and $10{\sim}20%$ respectively, on the viewpoint of yield and bulkiness. The optimum mole ratio of $BaCI_2$ to $BaSO_4$ was in the range of $1.50{\sim}2.0$ and the optimum mole ratio of $BaCI_2$ to $BaSO_4$ was in the range of $1.50{\sim}2.0$ and the optimum reacting time range was $15{\sim}20$ minutes. The optimum drying temperature range was $110{\sim}130^{\circ}C$ from the viewpoint of yield, but it was $90{\sim}110^{\circ}C$ on the basis of bulkiness. Apparent viscosity of barium sulfate suspensions dispersed in various concentrations of Na. CMC was measured by using Brookfield synchrolectric viscometer model LVT, the relative equation, log ${\eta}_{sp}=A+B.{\phi}$ was examined and the equation was found to agree fairly well. 1 w/v% Na. CMC aqueous solution and 0.1 volume fraction of $BaSO_4$ powder were optimum in the preparation of $BaSO_4$ suspension showing highest viscosity at infinite shearing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.1
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• pp.105-113
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• 1995

Procedures for isolatin of chitin have been developed from crab(Chionoecetes opilio) shell waste with 26. 65% chitin on a dry basis. Optimal conditions for demineralization of crab shell were 1N HCl at ambient temperature for 30min with a solids to solbent ratio of 1 : 15(w/v). Optimal deproteinization involved treatment with 5% NaOH at $65^{\circ}C$ for 1 hr with a solids to solvent ratio of 1 : 15(w/v). Effective decoloration was achieved by bleaching with 0.32% sodium hypochlorite solution for 3min with a solids to solvent ratio of 1 : 10(w/v). Particular attentin was given to characterization of the physicochemical properties of the crab chitin. Chitins, from four different mesh sizes of crab shell, did not show significant differences in nitrogen and ash compositions. Bleaching decreased the viscosity of chitin but did not affect its solubility.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.867-876
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• 1987

Corrosion fatigue fracture with change in the grain size of M.E.F. dual phase steel is investigated in 3.5% NaCI aqueous solution at pH 2, 4, 6, 9, and 11. Generally speaking, decrease in corrosion fatigue life is strongly dependent on decrease in pH and slightly on the grain size. For the B material with the big grain size, the fatigue life is small due to its large reduction ratio of corrosion fatigue life. The influence of grain size on the reduction ratio of corrosion fatigue life is large at pH 11-6. Whi9le at pH 4-2 the reduction ratio of corrosion fatigue life only depends on the corrosion effect. The larger grain size and the lass pH result in the greater influence on corrosion fatigue crack propagation rate. As pH decreases, the plateau portion in the crack propagation rate curves of the B material are distinct. Crack propagation rate curves become slow down at high .DELTA.K range because crack closure effect by minute corrosion products inside crack causes the oxidation corrosion action less effective for a certain period of time. In A material with small grain size, fatigue life is increased in proportion with increase of martensite intergranular which brings forth restraining the crack propagation decreases crack propagation rate. Corrosion pit which is created in the surface of specimen is found at pH 6,4 and 2 which is noticeable and the unevenness of the surface of the specimen becomes severe as pH decreases. The unevenness of corrosion fatigue fracture surface is severe as the effect of pH increases i.e. as pH decreases. In proportion with increase in the grain size and decrease in pH, the aspect of brittle fracture becomes evident.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1404-1411
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• 1993

This study was undertaken to investigate the corrosive wear charateristics upon various transformation condition of austempered low-alloy ductile cast iron in corrosive environments against mating specimen made of the hardened SM45C. The corrosive wear test was carried out by rubbing the annular surface of two test pieces in distilled water and aqueous solution at constant sliding speed of 0.5m/s. In severe wear region, the corrosive wear rate Wc increased hastily with NaCl concentration owing to intermetallic adhesion but Wc went down slowly in mild wear region due to lubricating effect of the corrosion product. The critical sliding distance decreased with increasing NaCl concentration due to increased generation rate of the corrosion product and the specific corrosive wear rate has maximum in 1% NaCl aqueous solution at mild wear region. With the variation of matrix, the corrosive wear resistance of the fine acicular bainite was higher than that of coarse upper bainite because of reducing the local cell reaction by carbides. A growth in volume fraction of retained austenite in matrix increased the Wc due to soften surface, but has a declining tendency of Wc in mild wear region.

• Korean Journal of Materials Research
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• v.6 no.10
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• pp.1025-1033
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• 1996

본 연구에서는 0.5M NaCI 용액내에서 일어나는 고분자재료로 피복된 강의 퇴화현상을 광학현미경 관찰 및 A.C. impedance spectroscopy를 이용하여 연구하였다. 강의 부식은 고분자재료로 피복된 강의 경우 국부부식(localized corrosion)의 형태로 나타난 반면, 피복되지 않은 강의 경우에는 전면부식(uniform corrosion)의 형태로 진행되었다. 고분자재료로 피복된 강의 부식이 국부적으로 진행되는 것은 피복층내에 존재하는 기공이나 크랙과 같은 결함 등에서 부식이 선택적으로 일어나기 때문으로 사료된다. 피복층의 박리(delamination) 현상은 고분자재료로 피복된 강/구리 갈바닉쌍(galvanic couple)의 경우 구리표면 위의 피복층에서만 관찰되었다. 이는 캐소드(cathode)로 작용하는 구리의표면에서 산소의 환원반응에 의해서 형성된 수산화이온(OH-)이 피복층의 박리를 조장하고 있음을 보여준다. 또한, 고분자재료 피복층의 파손 현상은 고분자재료/강의계면에서 석출된 부식생성물에 의해서 크게 조장되고 있음을 알 수 있다.

• Journal of the Korean Ceramic Society
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• v.42 no.7 s.278
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• pp.461-468
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• 2005

Transparent TiO$_{2}$ sols were prepared by hydrothermal synthesis to heat Ti precursor solutions, from Ti hydroxides obtained with neutralizing aqueous TiOCl$_{2}$ solutions having various concentrations of NaCI by aqueous NaOH solution, in the autoclave at 120$^{\circ}C$ The photocatalytic abilities of glass beads coated with the sol for gaseous benzene were evaluated. As a result, it was found that due to the increase of brookite phase in TiO$_{2}$ by controlling the concentration of Na ion the optical absorption of TiO$_{2}$ increases toward long wavelength but that in the area of short wavelength becomes relatively low and consequently the photocatalytic performance of TiO$_{2}$ thin film for benzene gas rather decreases, compared to that of composite film of anatase and brookite phases. These results suggest that in order for coated TiO$_{2}$ thin film to have high dissociation performance for benzene gas it is effective to form anatase and brookite phases compositely in TiO$_{2}$.

• Environmental Engineering Research
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• v.22 no.3
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• pp.312-319
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• 2017

The treatment of dyeing wastewater is not easy because dyes are mainly aromatic, heterocyclic compounds. The most effective technologies and methods to treat dyeing wastewater are costly and involve materials that are difficult to regenerate after use. Therefore, it is necessary to develop cost-effective, eco-friendly technologies to treat dyeing wastewater. The aim of this study was to investigate the removal of sulfur blue 11 (CI 53235) anionic dye using methyl esterified sericite (ME-sericite) adsorbents in an aqueous solution. The results are discussed in terms of the ME-sericite particle size, temperature, pH value and initial sorption rate according to the initial sulfur blue concentration. In addition, we analyzed the adsorption kinetics using a Pseudo-second-order model with the desorption and reusability. The methyl esterification caused a considerable increase in the specific surface area from 4.45 to $17.62m^2/g$. The ME-sericite adsorbents successfully removed > 98% of the sulfur dye in the aqueous solution. For the adsorption of 1 mg of sulfur dye, approximately 4.6 to 6.6 g/L ME-sericite were required. The desorption process was carried out by mixing a NaOH eluent to desorb 90.56% of the sulfur dye with 2 h of contact time. Thus, the ME-sericite is a promising adsorbent to treat dyeing wastewater due to its low dose requirement, high removal efficiency and inexpensive material.