• Journal of the Korea Concrete Institute
• /
• v.19 no.5
• /
• pp.639-646
• /
• 2007

This study performed several tests for the durability of the concrete coated with nano synthesis ceramics which do not contain volatile organic compounds harmful to environment. The tests were adhesion test on dry and humid concrete, SEM test, MIP analysis, carbonation, chloride diffusion by electronic facilitation, freezing-thawing resistance, alkaline resistance, and brine resistance test. In the adhesion test on dry and humid concrete, nano synthesis ceramics coating produced the highest results among all the coatings tested. Nano synthesis ceramics adhered solidly on the concrete surface. The adhesive strength seemed to result from the hydrogen bond between nano synthesis ceramics which are inorganic and generated by hydrolysis and re-condensation reaction and the concrete's hydrates such as calcium silicate aluminate or calcium silicate hydrate. SEM test and MIP analysis results show surface structure with finest crevices pore in the nano synthesis ceramics coating applied concretes. In the carbonation, chloride diffusion, and freezing-thawing resistance tests, the concretes with nano synthesis ceramics coating indicated the best results. Based on these test results, further progress in application of nano synthesis ceramics coatings to various concrete structures including costal structures and sewerage arrangements can be expected.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.8 no.2
• /
• pp.107-117
• /
• 1975

Alaska pollack caught in the Northern Pacific Ocean and frozen aboard vessel are skipped to the plant and processed into frozen fillets. In the present paper quality changes during thwaing, refreezing and storage at $-20^{\circ}C$ are discussed. Natural, running-water, vacuum and steam thawing were employed as thawing methods. And contact plate, air blast, immersion in dry ice-alcohol solution freezing and storage at $-5^{\circ}C$ were applied to refreeze the thawed fillets. As quality factors content of drip released, salt-extractable protein, VBN, DNA in the drip and pH were determined. In addition, bacteriological tests were also carried out along with the whole process. In thawing of round material, the vacuum thawing was more effective than any other method, resulting in drip, salt-extractable protein $(N\%)$, VBN and DNA as $4.4\%,\;1.82\%,\;16.21mg\%$ and $13.70\;{\mu}g/ml$, respectively. Storage at $-5^{\circ}C$ as refreezing method yielded lower in drip and DNA content but similar to or slightly higher in both salt-extractable protein and VBN, which might postulate that the quality of the frozen fillet depends not largely on the secondary freezing but on the conditions of thawing and primary freezing. It seemed that most of the bacterial flora in thawed fillet came from skin and viscera of fish, worker's hands, utensils and other processing facilities, since sanitary indicative bacteria were not detected in the frozen flesh of round Alaska pollack. Bacterial quality of fillet varied with thawing methods, vacuum thawing appeared more sanitative compared with other methods as natural, running-water, and steam thawing. Bacterial colonies isolated from the thawed fillet were composed of $73.8\%$ Gram negative rod shape, $4.9\%$ Gram positive rod shape, $18.0\%$ cocci, and $3.3\%$ yeast. Decreasing rate of coliform group of the fillet during the storage at $-20^{\circ}C$ for 30 days was more than $70\%$ and that of plate count was less than of coliform group.

• Journal of Conservation Science
• /
• v.34 no.3
• /
• pp.143-155
• /
• 2018

In this study, we investigated the properties and manufacturing methods of soil mural finishing layers fabricated using animal glue, starch adhesive(wheat paste), and Dobak glue. We assessed the workability and weatherproofing properties of the earthen plaster and finishing layers fabricated using concentrations of 3%, 5%, 7% and 10% for each adhesive. The results showed that a mixture using 3% or 5% starch adhesive or 3% Dobak glue was suitable for constructing the finishing layer. For finishing layers made with animal glue, earthen plaster had poor workability. It was dry and easily broken as the concentrations of animal glue increased. However, specimens made with low concentrations of animal glue did not exhibit surface deterioration after a freezing-thawing test. Therefore, animal glue mixtures could possibly be used for constructing finishing layers in concentrations lower than 3%. Mixtures containing starch adhesive produced plasters with good workability. Additionally, starch adhesive enhanced compression strength. However, when starch adhesive was mixed at concentrations above 7%, the surface exhibited roughening and staining in freezing-thawing tests. When Dobak glue was used in mixtures, it enhanced compression strength, but concentrations above 5% produced specimens with surface cracking. For concentrations of 3%, there were no cracks and the specimens were stable after freezing-thawing tests, so concentrations below 3% of Dobak glue are suitable for constructing finishing layers. We expect this study will be useful for restoring the traditional technology of soil mural finishing layers and suggest using adhesives to construct the finishing layer.

• CELLMED
• /
• v.2 no.4
• /
• pp.36.1-36.4
• /
• 2012

This study was carried out to investigate the neurobehavioural effects of the smoking of Carica papaya leaves based on ethnopharmacological information. Twenty -four rats used for the study were grouped into four groups namely; Groups 1 (Control, unexposed to any smoke) and Groups 2 - 4 (exposed to smoke from varying amount of pawpaw leaf powder). Groups 2, 3, and 4 were exposed to smoke from 6.25 g (low dose), 12.50 g (medium dose), and 18.75 g (high dose) of dry pawpaw leaves respectively in a smoking chamber twice daily for 21 one days with each exposure lasting 3 min. The spontaneous motor activities and locomotory behaviour of the animals were assessed using an open field maze and hole board maze test. The results showed that the smoking of Carica papaya leaves led to a significant (p < 0.05) increase in locomotory activities from $33.36{\pm}3.36$ (control) to $66.50{\pm}6.16$ (high dose), number of head dips (from $8.50{\pm}0.36$, to $12.83{\pm}0.87$) and rearing behaviour (from $14.83{\pm}0.74$, to $27.0{\pm}1.46$). However, the freezing durations as animals were introduced into the maze and grooming behaviour were significantly (p < 0.05) reduced in the treated groups. In conclusion, the increased ambulations and exploratory behaviours imply that the anxiety level is low in the treated groups compared to the control group which thus confirms that dry Carica papaya leaf may possibly contain psychoactive substance(s) that become active when smoked.

• Macromolecular Research
• /
• v.12 no.4
• /
• pp.367-373
• /
• 2004

We have developed a rigorous heat treatment method to improve the biocompatibility of chitosan as a tissue-engineered scaffold. The chitosan scaffold was prepared by the controlled freezing and lyophilizing method using dilute acetic acid and then it was heat-treated at 110$^{\circ}C$ in vacuo for 1-3 days. To explore changes in the physicochemical properties of the heat-treated scaffold, we analyzed the degree of deacetylation by colloid titration with poly(vinyl potassium sulfate) and the structural changes were analyzed by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffractometry (WAXD), and lysozyme susceptibility. The degree of deacetylation of chitosan scaffolds decreased significantly from 85 to 30% as the heat treatment time increased. FT-IR spectroscopic and WAXD data indicated the formation of amide bonds between the amino groups of chitosan and acetic acids carbonyl group, and of interchain hydrogen bonding between the carbonyl groups in the C-6 residues of chitosan and the N-acetyl groups. Our rigorous heat treatment method causes the scaffold to become more susceptible to lysozyme treatment. We performed further examinations of the changes in the biocompatibility of the chitosan scaffold after rigorous heat treatment by measuring the initial cell binding capacity and cell growth rate. Human dermal fibroblasts (HDFs) adhere and spread more effectively to the heat-treated chitosan than to the untreated sample. When the cell growth of the HDFs on the film or the scaffold was analyzed by an MTT assay, we found that rigorous heat treatment stimulated cell growth by 1.5∼1.95-fold relative to that of the untreated chitosan. We conclude that the rigorous dry heat treatment process increases the biocompatibility of the chitosan scaffold by decreasing the degree of deacetylation and by increasing cell attachment and growth.

• Journal of Korean Society of Forest Science
• /
• v.110 no.3
• /
• pp.406-418
• /
• 2021

This study was conducted to evaluate optimal storage techniques for bare root plants and container seedlings of Quercus variabilis and Zelkova serrata in order to maintain high quality of seedlings until planting. Refrigerated storage treatments were given at two temperatures (-2℃ [freezing] and 2℃ [cooling]) for nine different durations (0, 15, 30, 60, 120, 180, 240, 300, and 360 days after storage). We analyzed total nonstructural carbohydrate (TNC) content and measured shoot moisture content (SMC) during the storage stage and survival rate (SR) and dry weight during the planting stage of seedlings. The TNC content and SMC of the seedlings of the two species decreased with an increase in storage duration. The TNC content of seedlings rapidly decreased after 180~240 days of storage. The TNC reduction rate in the freezing treatment was lower than that in the cooling treatment. Also, with an increase in the storage duration of the two species, the SMC reduction rate in the cooling treatment increased in comparison with that in the freezing treatment. In both the species, the SR after planting decreased rapidly after 60 days of cooling storage and 180 days of freezing storage, respectively. The SR after planting was less than 60% when the TNC content for both the species dropped below 20 mg g^-1. In addition, the SR was lower than 80% when SMC measured before storage decreased by approximately 30% and 20% for Q. variabilis and Z. serrata, respectively. Our results suggest that cooling (1~2℃) storage is recommended for a short-term period (2 months or less), whereas freezing (-2~-4℃) storage is suitable for longer periods (2~6 months). These optimal storage techniques, allied with seedling harvesting and handling systems, will improve the quality of seedling production in nursery stages and increase seedling growth performances in plantations.

• Journal of the Korea Institute of Building Construction
• /
• v.5 no.4 s.18
• /
• pp.115-120
• /
• 2005

In recent years, polymer-modified mortars using polymer dispersions have been widely used as finish and repair materials in the construction industry because of their excellent properties compares to those of ordinary cement mortar. Especially, the adhesion improvement of ordinary cement mortar and concrete has attracted a great deal of attention from researchers, and several unique and simply applicable techniques for the adhesion improvement have been developed. The purpose of this study is to evaluate the abrasion resistance of polymer-modified mortar according various curing methods. The polymer-modified mortar are prepared with various polymer-cement ratios, and are subjected to three curing methods such as dry rure, standard cure and freezing and thawing cure after two curing methods, and then tested for abrasion. From the test results, the polymer-modified mortars with various polymer-cement ratios have some superior abrasion resistance compared with plain mortar. The abrasion resistance of polymer-modified mortars increase with an increase in the polymer-cement ratio, and is better under water cure than any other curing methods. It is concluded that the abrasion resistance of cement mortar is markedly improved by modifying of polymer dispersion.

• The Korean Journal of Food And Nutrition
• /
• v.8 no.3
• /
• pp.239-252
• /
• 1995

The results which were examined changes In contents of constitutive lipid and fatty acid during the natural drying of Pacific Saury were as follows. During the natural drying of Pacific Saury, offal lipid and moisture contents gradually decreased. In the survey of rancidity degree extracted lipid of Pacific Saury, peroxide value was gradually Increased, TBA and acid value were radically increased thereafter 9 days of drying. Neutral lipid, phospholipid and glycolipid contents of total lipid were 95%, 4% and 2%, respectively, and in the neutral lipid, content of TG was more than 90%, and in the phospholipid, contents of PC and PE were 45∼85%, 27∼34%, respectively. Fatty acid composition of total lipid was substantially higher in C18:0 and C20:1, C22:1, C22:6 contents and fatty acid composition of neutral lipid was higher In C22:1, C22:1, contents and fatty acid composition of phospholipid was the highest in C22:6 content. In the fatty acid composition of glycolipid, monounsaturated fatty acid content has substantially higher, C16:0 content was gradually Increased In saturated fatty acid and C22:1 content was gradually decreased in monounsaturated fatty acid. It showed that fatty acid composition of triglyceride has higher in monounsaturated fatty acid content and contents of C20:1, C22:1 was gradually decreased.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.17 no.2
• /
• pp.3778-3783
• /
• 1975

The objective of this study is to determine an appropriate cement of soil-cement in which silty soil of salty tidal flat with low plasticity was used. Physical, chemical and mechanical tests were conducted to find out the standard properties of the soil to be used. Various cement contents used in this test were 8%, 10%, 12%, and 14%, and the compressive strength was tested after 7 days and 28 days of standard curing in the above each cement content respectively. The results obtaind are summarized as follows. 1. As the cement content was increased from 8% to 14%, Maximum dry density (M.D.D.) and optimum moisture content (O.M.C.) were not changed remarkably. 2. Density of soil-cement was directly proportional to cement content and inversely proportional to water content. 3. OMC was generally decreased in proportion to the increase of cement content. 4. Compressive stranth was directly proportional to centent and inversely proportional to water content. 5. In freezing and thawing test, maximum loss of 10% in the total Weight was found on the 8% cement mixture. and This loss was rapidly decreased to 2% when the Cement content of the mixture was more than 10%.

• Corrosion Science and Technology
• /
• v.16 no.3
• /
• pp.141-150
• /
• 2017

Impregnating with quality silicone water repellent on the concrete surface is an effective method of protecting concrete. Quality silicone water repellent has been widely used in the engineering profession because of its desirable properties such as hydrophobicity, keeping concrete breathable and preserving the original appearance of the concrete. The companies in China that produce silicone water repellent are listed. Test methods in the specifications or standards about silicone water repellent in China are summed. The test methods relative to durability of concrete impregnated with silicone water repellent (such as resistant to chloride ion penetration, resistant to alkali, resistance to freezing and thawing and weatherability etc.) and the constructive quality (such as water absorption rate, impregnating depth and the dry velocity coefficient etc.) are compared and analyzed. The results indicate that there are differences among test methods relative to different specifications with the same index and therefore, confusion has ensued when selecting test methods. All test methods with the exception of the method of water absorption rate by using a Karsten flask are not non-destructive methods or conducted in a laboratory. Finally, further research on silicone water repellent during application is proposed.