• Journal of The Korean Society of Grassland and Forage Science
• /
• v.12 no.3
• /
• pp.30-40
• /
• 1992

The area of grassland established and the arable land in forage production have been decreased recently in Korea. As a result, forages available from the grassland and the arable land provided only 40% of the total roughage consumed by cattle in 1991, compared with 54% in 1989. The decreasing trend of the forage production has been impinged on by a number of legislative. socio-economic. technical and other constraints negatively affecting grassland and forage development. Consequently. effective systems and strategies are quite necessary to have sustainable grassland farming in Korea. In spring and autumn, temperatures are too low for subtropical forage crops, and the summer monsoon climate is another serious limitation to the use of cool-season species. Therefore it is an imperative that not only the research-based grassland development but also the forage crop production should be strongly supported by the government authorities to overcome such climatic limitations. Private forest land holdings are of relatively small units in Korea. Accordingly. it is necessary and important to enlarge the forest land holdings per farm to develop as economic units of grassland. For this the government should introduce new policy measures such as for example: long-term leases of Sorest land and the idle arable land of absentee owners ; rational rental system of national and public forest lands; integrating livestock and forest production. All the laws and regulations standing in the way of the grassland development in forest lands should be modified and revised to open the way for much easier development of grassland. It is also proposed that a high level of financial incentives -hould be provided for structural improvements for the grassland development. They may be: mechanization facilitation, construction of new roads relating to grassland, and land exchange and consolidation. And it is basically necessary that financial enumeration or profits must be garanteed in order to motivate farmers to keep up farming continuously. For more efficient grassland development in mountainous areas, reorganization of Alpine Experiment Station and NAB1 Namwon Branch Station may be needed. Research should be strengthened for completion of pasture mixtures, development of maximum forage production methods with a view to saving labor and reducing production costs, introduction of grazing and forage conservation techniques. and utilization of rice straw as more palatable and nutritious forage source. In order to have more efficient and effective transfer of advanced forage production technologies to livestock farmers the user-clients. it is also essential that special training measures should be given to livestock farmers through making greater use of specialized research and extension workers.

• Food Science and Preservation
• /
• v.14 no.5
• /
• pp.526-530
• /
• 2007

The effects of kwamaegi (0, 6, 12 and 18%, all w/w) on the quality characteristics of Kimchi during fermentation at $10^{\circ}C$ were investigated. The mixtures are denoted KK. The late of decrease in pH during KK fermentation was lower than that of control. The number of total microbes (T) in Kimchi controls fermented for 14 days did not differ, and were in the range of $8.64{\sim}8.68\;log\;CFU/g$, whereas the numbers of lactic acid bacteria (L) in KK were higher than in controls. The L/T(%) was 78.41 in control, 85.76 in 6% KK and $93.68{\sim}94.25%$ in the 16% or 18% KK samples. The hardness of tissue ($2.98{\sim}3.66{\times}10^7\;dyne/cm^2$) in KK fermented for 14 days was higher than that of control ($2.67{\times}10^7\;dyne/cm^2$). The content of alcohol-insoluble substances in KK juice (1.281.08 g/100 g) was lower than that of control (1.45 g/100 g). In sensory evaluation, the appearance and texture of KK were better than those of control. Although some fishy flavor was noted in KK, this did not affect acceptability. Sourness was less, whereas ripened taste and overall acceptability were higher in KK (especially 12% KK) compared to control.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.7
• /
• pp.779-784
• /
• 2011

This study was carried out on the crack healing of three types of SiC ceramics based on a $SiO_2$ additive, taking into account the roughness of the polishing plate used for polishing the specimens. The mixtures were subsequently hot-pressed in $N_2$ gas for one hour under 35 MPa at 2053 K. In these specimens, the optimized crack-healing condition was 1373 K for one hour in air. The crack-healing material of the cracked part was the glassy phase of $SiO_2$ that was formed by the oxidation of SiC. In the optimum healing condition, the bending strength of non-polished SiC ceramics was not completely recovered. However, the bending strength of the SAY specimen was excellent, considering the economic aspects of SAY, SAYS-1, and SAYS-2. The SAY specimen is definitely superior to the others after an hour of heat treatment. There was a decrease in the number and size of defects in the specimen polished by using a $125-{\mu}m$ polishing plate; however, the micro-surface defects were not completely repaired. The specimen polished by using a 40-${\mu}m$ polishing plate showed little voids or surface defects after an hour of heat treatment. The bending strength of the specimen mirror-polished by using a 6-${\mu}m$ polishing plate was completely recovered.

• Journal of the Korean Applied Science and Technology
• /
• v.34 no.4
• /
• pp.1066-1075
• /
• 2017

This study was carried out to determine the functional works and basic ingredients of Sagoonja-Tang on sponge cake. The experimental groups consisted of 6% mixtures of five (Ed-confirm the number) kinds powders : S1 for Sagoonja-Tang powder, S2 for Panax ginseng, S3 for Poria cocos, Koidz, S4 for Atractylodes macrocephala, and S5 for Glycyrrhiza uralensis Fisch. The volume of sponge cake somewhat decreased after adding the ingredients, and the volume differences in order from highest to lowest, were control>S1>S3>S2>S4>S5. In the microbiological quality test, viable cell counts were high in control groups of sponge cake, and the numbers of viable cell for control sponge cake reached to $9{\times}10^7CFU/g$ on the 7th day of storage, and decreased to $2.5{\times}10^5CFU/g$ on the 10th day of storage. All sponge cakes added with ingredient's powder showed pretty low viable cell counts. Especially, the group S5 showed the lowest counts of $1.2{\times}10^2CFU/g$ on the 7th day of storing. In the texture analyses of sponge cake, All groups showed higher degree of hardness, gumminess and chewiness than SC. The antioxidative activity of the Sagoonja-Tang's ingredients was measured. The POV value measured was S5>S4>S3>S2 >S1>control in order of highest to lowest. In sensory test, the overall acceptability of sponge cake was from highest to lowest S3>SC S2>S1>S5>S4.

• Journal of the Korea Concrete Institute
• /
• v.16 no.1 s.79
• /
• pp.70-78
• /
• 2004

Although set accelerating agents are used generally in New Austrian Tunneling Method, the standards for test methods and quality of set accelerating agents are not prescribed domestically. In this study, the proprieties of the various standards and the characteristics of set accelerating agents for shotcrete were evaluated. The alkali contents of set accelerating agents based on silicate, aluminate and cement were higher than those of alkali-free ones. From the result, it is thought that the quality control of aggregate should be enhanced and that the number of test cycle of alkali-aggregate reaction should be increased. The setting times of cement paste with set accelerating agents based on silicate and alkali-free ones were different largely with mixing methods. Compressive strength of mortar with set accelerating agents based on silicate, aluminate and cement at one day satisfied the specifications of Korea Concrete Institute. However, the strength ratio compared to control mix at 28 days showed as $50{\~}65\%$ except for the alkali-free set accelerating agents. As a results of setting time and strength test, the establishment of domestic standards that can reflect the characteristics of materials and construction methods of tunnels and that can increase quality of set accelerating agents is required immediately.

• The Korean Journal of Nuclear Medicine
• /
• v.7 no.2
• /
• pp.1-12
• /
• 1973

The most commonly used methods for determining thyroxine binding globulin(TBG) concentration as the total thyroxine-binding capacity utilize electrophoretic seperation of serum. Although technically simple, the electrophoretic method is time consuming and is limited in the number of samples which can be run in a single assay. The author presented a single $T_4$ load ion exchange resin method as an approach to simplify the technique as with clinical practicability and results were analyzed. For construction of the standard curves, serum mixtures were diluted with barbital buffer.which effectively blocked $T_4$-binding to TBPA. For each serum dilution, a constant amount of $T_4-^{125}I$ and increments of unlabelled $T_4$ were added. After incubation in water bath, resin beads were dispensed to the samples which binded all $T_4$ not bound to TBG. The radioactivity in the supernatant was counted in the gamma scintillation counter. Each standard curve was plotted from the percent counts in the supernatant and total $T_4$ in each tube. Unknown samples were diluted to 1:40 and ran at a single $T_4$ loading concentration, and the TBG capacity of the samples was able to be read on the standard isobars. The following results were obtained. 1) Mean and standard deviation for TBG capacity in normal population was $28.6{\pm}5.09{\mu}g\;T_4/100ml$. 2) $24.9{\pm}3.87{\mu}g\;T_4/100ml$ in hyperthyroidism showed low TBG capacity comparing to normal population.(p<0.025) 3) $31.0{\pm}2.40{\mu}g\;T_4/100ml$ in hypothyroidism showed high TBG capacity tendency comparing to normal population. 4) Reversed correlationship existed between TBG capacity and $T_3$ resin uptake(r=-0.624), TBG capacity and serum $T_4$ value (r=-0.859), and TBG capacity and free thyroxine index(r=-0.623). The author assumes that this method of assay is considerably simpler in instrumentation and technique than any other assays traditionally being used, and seems to be more practical for routine clinical laboratory use.

• Journal of the Korea Concrete Institute
• /
• v.26 no.4
• /
• pp.507-515
• /
• 2014

Although the construction joints of a concrete structure are properly treated with some measures, leakage has frequently occurred. A series of tests on the bond characteristics between new and old concrete were carried out in this study, assuming that the leakage at the construction joints has certain relationship with the bond of concrete. To assess the bond characteristics under various conditions, a number of specimens were made that have an interface between new and old concrete and bond strength, flexural strength and splitting tensile strength were measured. Main test variables are type and amount of mineral admixtures, treatment method of the interface and type of waterstops. In addition, the effects of placing interval between the concrete and of the age of the strength tests were investigated. The test results showed a slightly increased bond strength when applying mineral admixtures, which can be attributed to the interface filled with the calcium silicate hydrate that is formed by pozzolanic reaction. On the other hand, the bond strength was higher when the interface was treated rough and dry, and the roughness of a waterstop affected the bond capacity of the waterstop. Also, an assessment is required that considers the type of strength test because the bond strength varied according to the test methods.

• Analytical Science and Technology
• /
• v.19 no.5
• /
• pp.369-375
• /
• 2006

Calibration gas mixtures were prepared using dynamic volumetric method according to ISO 6145-5 and the uncertainty was evaluated. Ten identical capillaries with 0.25 mm in inner diameter and 50 cm in length were applied in this system. Dilution ratio of parent gas was determined by the number of capillaries that passes parent gas and that passes balance gas through. Capillaries were made of Teflon which had good chemical stability against adsorption of gaseous substances. Mechanical valves were introduced in this system in order to minimize the thermal effect of solenoid valves. Concentration of prepared gases were compared with master grade standard gases in cylinders made by RiGAS Co. and calibration of the instrument were completed using comparison method according to ISO 6143. Experimental results showed that the coefficient of variance of diluted oxygen standard gases showed less then 0.2% in most dilution range, that of diluted hydrogen sulfide standard gases showed less then 1.0%. Therefore, it is proven that the standard gases prepared by this system are appropriate to be used as a calibration standards in ambient monitoring, etc.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.2
• /
• pp.179-188
• /
• 2011

Experiments were conducted in a constant-pressure combustion chamber to investigate the effects of hydrocarbon addition on cellular instabilities of syngas-air flames. The measured laminar burning velocities were compared with the predicted results computed using reliable kinetic mechanisms with detailed transport and chemistry. The cellular instabilities that included hydrodynamic and diffusional-thermal instabilities of the hydrocarbon-added syngas-air flames were identified and evaluated. Further, experimentally measured critical Peclet numbers for fuel-lean flames were compared with the predicted results. Experimental results showed that the laminar burning velocities decreased significantly with an increase in the amount of hydrocarbon added in the reactant mixtures. With addition of propane and butane, the propensity for cell formation was significantly diminished whereas the cellular instabilities for methane-added syngas-air flames were not suppressed.

• Journal of the Korea Concrete Institute
• /
• v.22 no.5
• /
• pp.617-624
• /
• 2010

This paper reports on a comprehensive study on the mechanical properties of expansive fiber-reinforced strainhardening cement composite (SHCC) materials containing various replacement levels (0, 8, 10, 12 and 14%) of an expansive admixture and 1.5% polyethylene (PE) fibers volume fraction. A number of experimental tests were conducted to investigate shrinkage, compressive strength, flexural strength, and direct tension behavior. Test results show that as expected, the different replacement levels of an expansive admixture have an important effect on the evolution of the free shrinkage of SHCC with a rich mixture. At the volume fraction of 1.5%, PE fibers in normal SHCC reduce free shrinkage deformation by about 30% in comparison to plain mortar. The replacement of an expansive admixture in SHCC material has led the SHCC to a better initial cracking behavior. Enhanced cracking tendency improved mechanical properties of SHCC materials with rich mixtures. Note that an increase in the replacement of expansive admixture from 10% to 14% does not lead to a significant improvement for mechanical properties; this implies that the replacement of 10% expansive admixture is sufficient.