• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.1
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• pp.8-17
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• 1987

Four foreign pasture cultivars such as Lotus corniculatus cv. Maitland, Trifolium pratense cv. Deben, Lolium perenne cv. $S_{23}$ and .Dactylis glomerata cv. $S_{26}$ were tested with "Kwisan" series, a common upland soil in Southern part of Korea. The cultivars in single or mixture were grown in pot with two levels of light intensity, i.e. a full sun light condition and 50% interception. Dry matter yield of top and root and their seasonal changes, the number of tillers or branches per plant and finally competative effects of mixtures were evaluated by estimating the expected yield, relative yield totals and compensation index. The results are summarized as follows: 1. Maitland showed a significant decrease in dry matter yield in shade condition, but the number of branches of Maitland was higher than those of Deben. 2. Maitland showed higher dry matter yield than Deben during the mid-summer period, while $S_{23}$, showed higher dry matter yield than $S_{26}$ during early season. 3. Mixtures of $S_{23}$ and Maitland, and $S_{26}$ and Deben gave better response to grasses by increasing the number of tillers in shade condition. 4. Combinations of Lotus corniculatus cv. Maitland and Dactylis glomerata cv. $S_{26}$ and Trifolium pratense cv. Deben and Dactylis glomerata cv. $S_{26}$ gave higher relative yield totals and higher compensation index, which envisages that the pasture establishment rates can be enhanced when those mixtures were sown by the oversowing method in the upland soil where phosphate level is very low and infertile in general.n general.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.314-321
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• 2005

Objectives. The purpose of this study was to compare the shade changes in wet and dry conditions of natural teeth using two different intra-oral colorimeters. Materials and methods. Twenty volunteer subjects have no restorations and fillings in the maxillary central incisors were involved in this clinical study. The color of tooth was measured by two different instruments that were a Shade $Scan^{TM}$ System and a VITA $Easyshade^{(R)}$, Five times consecutive measurements were done for each subject with both instruments. Groups of measurement are an initial wet condition as control, dry in 5 minutes, 15 seconds after re-wetting with saliva, re-wetting after 5minutes and re-wetting after 30 minutes. Using ShadeScan $System^{TM}$, tooth image was captured and converted to the mapping image of Vitapan 3D master. Three main shades were chosen from each subject and calculated the area in Global Lab Image software. Data were analyzed using paired T-Test and Wilcoxon Signed Ranked Test. Using VITA $Easyshade^{(R)}$, color differences($\Delta$E) between measurements were analyzed with one sample T-test. Results. Using ShadeScan $System^{TM}$, there were significant differences between control group and dry(P=.023), dry and re-wetting 15 seconds, 5 minutes, 30 minutes as well(P=.021, P=.017, P=.030) in comparison of primary shade. However, comparing three main shades, there was no significant difference between control and dry(P=.105). Using VITA $Easyshade^{(R)}$, color differences($\Delta$E) between control and dry, dry and re-wetting 30 minutes were statistically different(P=.002, P=.022). Conclusion. Primary shade could be changed in dry and wetting procedure in time, however there was no significant shade changes in overall.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.294-300
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• 1985

This experiment was carried out to study the root and the other major agronomic traits of barley cultivars at the greenhouse and natural conditions for the accelerating of breeding generation. The barley cultivars tested in this experiment were Kangbori, Olbori and Suwon 18. In early stages, total dry weight of barley was vigorously increased at the greenhouse condition, whereas it was less increased than that of natural condition after heading stages. In dry root weight, it was decreased at natural condition rather than greenhouse condition. The appearance of harvest dry root weight was at four weeks after heading at natural condition and seven weeks after heading at greenhouse condition, respectively. It showed different tendency in T/R ratio, indicating the continuous increased at natural and greenhouse condition, even if there is more or less decrease until tillering stage at greenhouse condition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.4
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• pp.412-420
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• 2015

Even though phosphorus (P) is essential element for plant growth and development, it is not enough for crop production in soil. To breed more P deficient tolerance rice, screening and selection in rice population is needed. We tried to develop more simple and rough screening method for breeding of P deficient tolerance rice. In P deficient condition, tiller number was dramatically decreased among yield components in rice. Though this result, we confirmed tiller number could be the best marker in screening of P deficient tolerance rice. 480 rice genetic resources were cultivated in rice bed tray filled with P deficient soil for four weeks and each dry weight was measured. Among them, the 55 kinds of genetic resource were selected then cultivated in paddy field with 3 fertilizer conditions. Plant dry weight and tiller number in ripening stage were shown significant difference according to P condition. Plant dry weight and tiller number in ripening stage was highly correlated especially in P deficient condition. Furthermore, the tiller number in ripening stage and plant dry weight in rough screening were shown high degree correlation. Though these results, we might expect measuring of plant dry weight after cultivation in rice bed tray filled with P deficient soil could be a simple and effective screening method in selection of P deficient tolerance rice.

• Tribology and Lubricants
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• v.13 no.1
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• pp.21-27
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• 1997

The friction and wear behavior of undulated surfaces made of tin base babbit are examined experimentally at the low sliding speed with severe loading condition. Steel is used as counterface disk material under pin-on-disk type sliding condition. Undulated surfaces can improve the friction and wear properties under dry friction condition since undulated surfaces trap wear particles in their cavities and prohibit wear particles from agglomerating. However, under boundary lubrication condition, friction and wear properties of undulated surfaces are inferior to those of flat surfaces. It is shown that land width and the ratio of wear volume to cavity volume are the most important factors in friction behavior of undulated surfaces under dry friction condition, and there exists optimum land width minimizing friction and wear of undulated surfaces.

• Water Engineering Research
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• v.5 no.1
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• pp.1-16
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• 2004

The purpose of this study is to understand the characteristics of hourly PET(Potential Evapo Transpiration) variation estimated using Penman ET model. The estimated PET using Penman model was compared with measured ET. For this study, two subwatersheds were selected, and fluxes, meteorological data and soil moisture data were measured during the summer and winter days. During the winter days, the aerodynamic term of Penman ET is much greater than that of energy term of Penman ET for dry soil condition. The opposite phenomena appeared fer wet soil condition. During the summer days, energy term is much more important factor for ET estimation compared with aerodynamic term regardless of soil moisture condition. Penman ET, measured ET, and energy term show the similar hourly variation pattern mainly because the influence of net radiation on the estimation of Penman ET is much more significant compared with other variables. Even though there are much more soil moisture in the soil during the wet days, the estimated hourly ET from Penman model and measured hourly ET have smaller values compared with those of dry days, indicating the effect of cloudy weather condition.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.111-116
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• 2006

Tribologcal property of the ceramics used in severe condition was investigated and both $Al_2O_3$ ball and Al/SiC composite made by thermal spray process[TSP] were used as a specimen in this study. Four kinds of material couple in ball and disk specimens were tested in the dry condition by using ball-on-disk type tribo-tester. Friction coefficient, surface roughness, wear rate, and photograph of the worn surface were investigated. Generally, High SiC contents[$40{\sim}50%$] specimens showed very low friction coefficient below 0.05 and little wear rate in dry condition. And also, low SiC contents[0%] specimens showed a moderate wear rate and high coefficient of friction at the same condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.521-522
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• 2010

• Tunnel and Underground Space
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• v.7 no.2
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• pp.91-99
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• 1997

To stabilize the energy price, the more storage facilities of energy are required and among the storage methods of LPG and LNG, the method of storage at low temperature under normal confining pressure is considered. It is needed to understand the mechanical and thermal characteristics of rock under temperature variation so that the behaviors of rock can be predicted. In this paper, the variation of the rock charateristics of the Hwangdeung granite and the Boryung sandstone is studied at low temperature. The mechanical characteristics of rock under low temperatures are that as temperature decreased, unaxial compression strength and Young's modulus increased for Hwangdeung granite; strength and Young's modulus in wet condition were greater than those in dry condition. In the case of Boryung sandstone, as temperature decreases unaxial compression strength and Young's modulus increase but decrease below -10$0^{\circ}C$ in dry condition and below -16$0^{\circ}C$ in wet condtion. The mechanical characteristics of rock after cooling to previous temperature and thawing are that uniaxial compression strength and Young's modulus decrease as temperature decreases. Uniaxial compression strength and Young's modulus in wet conditon decrease more than those in dry condition. Brazilian tension strength decreases as temperature decreases.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.69-77
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• 2012

Relative density, used to express dynamics condition of sand quantitatively, is measured by RI Test, Standard Penetration Test and Cone Penetration Test. Each measurement method has demerits, which is complicated or needs a specific analysis instrument and an analysis of expert. Also the ground is in wet condition commonly because of an unsaturated zone between a saturated zone and a surface, so the behaviour of the ground has different engineering properties unlike the dry ground and it diminishes accuracy of measuring relative density. In this study, the correlation between relative density and penetration of fall cone test in dry condition and wet condition with variation of water content was analyzed and a simple measuring method for relative density was suggested. As a result, there were difference of penetration between dry sands and wet sands, the correlation between relative density and penetration showed linear expression and relative density could be measured by the linear relation.