• Applied Biological Chemistry
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• v.10
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• pp.107-112
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• 1968

In order to study the effect of potash on the growth and yields of Soybean at different level of soil fertility and application of fertilizer (nitrogen, phosphate and calcium), $2^3$factorical experiment was carried out by pat culture with variety 'Chang-dan-baec-muc' which is most spreaded variety in Korea. The experiment consisted of five replications in a randomized block experiment with three factors (soil, fertilization and potash). Treatment were at two levels; infertile and fertile soil, none and some of fertilization and potash. Thus, the experiment comprised eight treatment combinations which consisted of all combinations. The results of this experiment are as follows: 1. No effect of each of three factors on flowering date was found. 2. Leaf-yellowing and maturing date was quickened on the fertile soil but no effect of fertilization and potash was found. 3. More premature leaf-yellowing was found on the fertile soil. 4. Deeper leaf colour cuss showed on the fertile soil and in the case of fertilization but no effect of potash was found. 5. Increasing tendency of following character: length and width of leaf, height and dia of stem, number of branches and pods; was most remarkable on the fertile soil. Application of fertilizer showed also remarkable tendency of increasing, while increasing tendency of potash was the least. 6. Same tendency was found with following charactors; weight of total plant. stem and shell, and commercial grains, weight of 100 grain and number of commercial grains. 7. As the results of analysis of variance for weight of commercial grain it, was found the teach of the three factors increased soybean yields significantly (weight of commercial grain) but the effect of potash was less than the other two factors. No significant interaction was found among three factors. 8. Greater effect of potash on increasing soybean yields was found on the fertile soil, and in the case of fertilization.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.3
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• pp.174-183
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• 2014

Seabed beneath and near coastal structures may undergo large excess pore water pressure composed of oscillatory and residual components in the case of long durations of high wave loading. This excess pore water pressure may reduce effective stress and, consequently, the seabed may liquefy. If liquefaction occurs in the seabed, the structure may sink, overturn, and eventually increase the failure potential. In this study, to evaluate the liquefaction potential on the seabed, numerical analysis was conducted using the expanded 2-dimensional numerical wave tank to account for an irregular wave field. In the condition of an irregular wave field, the dynamic wave pressure and water flow velocity acting on the seabed and the surface boundary of the composite breakwater structure were estimated. Simulation results were used as input data in a finite element computer program for elastoplastic seabed response. Simulations evaluated the time and spatial variations in excess pore water pressure, effective stress, and liquefaction potential in the seabed. Additionally, the deformation of the seabed and the displacement of the structure as a function of time were quantitatively evaluated. From the results of the analysis, the liquefaction potential at the seabed in front and rear of the composite breakwater was identified. Since the liquefied seabed particles have no resistance to force, scour potential could increase on the seabed. In addition, the strength decrease of the seabed due to the liquefaction can increase the structural motion and significantly influence the stability of the composite breakwater. Due to limitations of allowable paper length, the studied results were divided into two portions; (I) focusing on the dynamic response of structure, acceleration, deformation of seabed, and (II) focusing on the time variation in excess pore water pressure, liquefaction, effective stress path in the seabed. This paper corresponds to (II).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.3
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• pp.160-173
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• 2014

Seabed beneath and near coastal structures may undergo large excess pore water pressure composed of oscillatory and residual components in the case of long durations of high wave loading. This excess pore water pressure may reduce effective stress and, consequently, the seabed may liquefy. If liquefaction occurs in the seabed, the structure may sink, overturn, and eventually increase the failure potential. In this study, to evaluate the liquefaction potential on the seabed, numerical analysis was conducted using the expanded 2-dimensional numerical wave tank to account for an irregular wave field. In the condition of an irregular wave field, the dynamic wave pressure and water flow velocity acting on the seabed and the surface boundary of the composite breakwater structure were estimated. Simulation results were used as input data in a finite element computer program for elastoplastic seabed response. Simulations evaluated the time and spatial variations in excess pore water pressure, effective stress, and liquefaction potential in the seabed. Additionally, the deformation of the seabed and the displacement of the structure as a function of time were quantitatively evaluated. From the results of the analysis, the liquefaction potential at the seabed in front and rear of the composite breakwater was identified. Since the liquefied seabed particles have no resistance to force, scour potential could increase on the seabed. In addition, the strength decrease of the seabed due to the liquefaction can increase the structural motion and significantly influence the stability of the composite breakwater. Due to limitations of allowable paper length, the studied results were divided into two portions; (I) focusing on the dynamic response of structure, acceleration, deformation of seabed, and (II) focusing on the time variation in excess pore water pressure, liquefaction, effective stress path in the seabed. This paper corresponds to (I).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.352-361
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• 1990

The reducing effect of wind injury was investigated using several wind-break nets in Youngdeok province where cold-wind damage is often occurred during rice growing season. The white-head damage of rice have been often occurred by typhoon during the period between August 15 to September 10 in the cold wind area of the eastern coastal during the last 11 years (1979-1989). This may suggest that the critical period for heading will be by August 15 in the regions. High evaporation coefficient, more than 250 due to typhoon passage over the regions resulted high injury of white head. Generally, the wind injury have been caused by warm and dry westerlies through Fohn apperance in Taebaeg mountains and by cool-humid wind which blows from coast to inland. The frequency of occurrence of the two types of typhoons were 25, 20%, respectively during rice cultivation. The instalation of wind-break net significantly reduced the wind blowing speed, depending on the net mesher with the higher effect in dence net. The distances between the net and cropping area also affect the wind speed: 23% reduction at 1m distance. 34% at 10m and 28% at 20m, respectively. The reducing effect was also observed even at 10 times height of the wind-break net. The instalation of wind-break net gave several effects on climate factor, showing that temperature increased by 0.8$^{\circ}C$(maximum), 0.7$^{\circ}C$(minimum), 0.6$^{\circ}C$(average) : water temperatures increased by 0.5$^{\circ}C$(maximum), 0.6$^{\circ}C$(minimum), 0.5$^{\circ}C$(average) : soil temperature increased 0.4$^{\circ}C$. The earlier heading and increasing growth rate, use of light, culm length, panicle number per hill, spikelet number per panicle, fertility and 1,000 grain weight were observed in the fields with the wind-break nets resulting in 10-15% increase in rice yield using 0.5${\times}$0.5cm nets. The increasing seedlings per hill gave higher grain yield by 13% in the cold wind damage regions of eastern coastals. and the wind-break was more significant in the field without the wind-break net. Wind injury of rice plant in the cold wind regions of eastern coastals in korea could be reduced by selection of tolerant varieties to wind injury, adjustment of transplanting time, and establishment of wind-break nets.

• Horticultural Science & Technology
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• v.29 no.5
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• pp.474-481
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• 2011

Potato late blight caused by the fungus Phytophthora infestans is one of the most vital diseases damaging the potato plant. It is for this reason that breeding potato cultivars resistant to late blight is now becoming a major concern around the world. The B3C1 clones has been introduced by the Highland Agriculture Research Center, RDA. The clones which came from International Potato Center in 2005 have a durable resistance to late blight. The clones were bred under a short-day condition in Peru. However, there was still no report on the adaptability of these clones to the long-day condition in Korea. Therefore, this study was conducted to evaluate the late blight resistance and major agronomic characteristics of B3C1 clones under Korea's long-day condition. This study was also done to generate genetic resources for developing new varieties resistant to late blight. In this study it was found out that in naturally infested field with P. infestans, AUDPC (area under disease progress curve) values of all B3C1 clones were significantly lower than those of the control varieties, 'Superior', 'Atlantic', and 'Haryeong'. It was found out that B3C1 clones had a high level of resistance to late blight and that they could be used as genetic resources to breed potato varieties with late blight resistance. However, several undesirable characteristics such as extremely late maturity, excessive growth of stems and stolons, and production of tubers that cannot easily be removed from the stolons were also observed. Among the twenty B3C1 clones, two clones, LB-8 (CIP393077.159) and LB-11 (CIP393371.159), were selected for cultivating at the highland area of Korea. Two B3C1 clones were crossed with Korean breeding lines and clonal selection for the progenies is still in progress.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.2
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• pp.116-120
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• 1991

Silage productivity of two sorghum hybrids. Pioneer(P) 931 and P 956, and green fodder productivity of a sorghum-sudangrass hybrid, P 988, were tested at four levels of seeding rates (1, 2, 3, and 4 kg/lOa). The 1st-cut of sorghum hybrids of P 931 and P 956 was made at milk ripe stage for silage on July 22 and 31, respectively and regrowth was harvested on Oct. 13. The 1st-and 2nd-cut of a sorghum-sudangrass hybrid were made at flag leaf emerging stage for green fodder on July 26 and Aug. 16 and 3rd-cut was harvested on Oct. 13. The results obtained are summarized as follows:1. Growth stage, culm length or plant height, and percent dry matter (DM) were similar among the seeding rates. Percent DM of sorghum hybrids ranged 26.9-31.2% regardless hybrids and t ~ m e of harvest. However, in the sorghum-sudangrass hybrid percent DM of the 1st-cut. 2nd-cut, and 3rd-cut ranged 10.0-10.7% 18.2-19.97% and 24.6-27.8% respectively.2. In sorghum hybrids crude(C) fiber content of P 931 was higher, but nitrogen free extract (NFE) was lower compared with those of P 956 and C. protein and C. fat were similar between two hybrids. However, C. protein and C. ash of sorghum hybrids were lower, but C. fiber and NFE were higher compared with those of a sorghum-sudangrass hybrid and C. fat was similar between two crops.3. Total DM yield was greater in the order of P 931>P 956>P 988. The optimum seeding rate for both silage yield of sorghum hybrids and green fodder of a sorghum-sudangrass hybrid was 2-4 kg/lOa. However, yield of the 1st-cut tended to increase as seeding rate increased.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.4
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• pp.257-267
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• 1993

Optimum pasture management during the summer season is an important factor to maintain good regrowth and persistence of pasture. The field experiment was carried out to investigate the effects of cutting management on growth and reserve carbohydrates in stubble. and on dry matter yield of orchardgrass dominated pasture during the mid-summer season. Three different cutting times(July 15, 25 and August 5) as a main plot and three cutting heights(3, 6 and 10cm) as a sub plot were disigned with three replications. The experiment was done at pasture of Changsung Agricultural High School in 1988. The results obtained were summarized as follows: 1. Temperature of soil surface and underground in the cutting of July 15 and July 25 was not showed significantly different, because of low intensity of radiation with a run of wet weather, and that of August 5 cutting tends to be lowed in high cutting height during the mid-summer season. 2. Amount of soil moisture against cutting height showed that high cutting had a low content. 3. Growth rate against regrowth of plant height, lear length and leaf area showed to be fast in high cutting. 4. Rapid recovery period of carbohydrate content after cutting and large amount of carbohydrate accumulation were showed in the cutting of July 15 and 25 compared with August 5 cutting in the reserve carbohydrate content against cutting of time and height during the mid-summer season. 5. Dry matter yield of the 4th and 5th cutting showed to be remarkable in July 15 cutting compared to those of July 25 and August 5. From the above results, it is suggested that the 10cm cutting height during the mid-summer season is the most effective for good regrowth, reserve carbohydrates and dry matter yield of orchardgrass.

• Journal of The Korean Society of Grassland and Forage Science
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• v.22 no.4
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• pp.265-272
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• 2002

Forage breeding laboratory of National Livestock Research Institute, R.D.A. has made interspecific hybrids of Lolium multiflorum $\times$ L. pratensis and intergeneric hybrids of Lolium $\times$ Festuca since 1984, and has collected ecotypes of Italian ryegrass since 1991. Growth characteristics of these hybrids and ecotypes were researched, and then these clone lines were named. Among these clone lines, the several clones that have polen fertility, high cold-tolerance, and similar heading time were used for making synthetics, Naehan 6, 7, 8, 9, with polycrossing method in 1997. Field experiments were carried out to compare the mophological and agronomical characteristics and forage productivity and quality of the synthetics with those of Italian ryegrass varieties, Barmultra and Hwasan 101. in Suwon and Yonchun from 1999 to 2000. Heading time of the synthetics were 22th to 24th May that belong to late-mature types to be similar to that of Barmultra and Hwasan 101 in Suwon. The synthetics were 101 to 106 c3n in plant length, medium or thick in thickness of stem, dark peen in leaf color, broad and long in flag leaf, strong in lodging resistance, and excellent in regrowth. Winter survivals of the synthetics were no different from that of Barmultra or Hwasan 101 in Suwon, but better than that of Barmultra or Hwasan 101 in Yonchun where was -10 to -12$^{\circ}C$ of minimum average air temperature in January or February. Dry matter(DM) yields of the synthetics were similar to DM 8,238kg per ha of Barmultra in Suwon, but in Yonchun, were more 7 to 13% than DM 7,291kg per ha of Barmultra. Forage qualities, IVDMD, ADF, NDF and TDN of the synthetics were lower than those of Hwasan 101, but higher than those of Barmultra.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.2
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• pp.100-105
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• 1985

To find out the optimum level of nitrogen fertilization and better distribution of application time for seed production of Festuca arundianacea S. (var. Alta), this filed experiment was performed at Livestock Experiment Station in Suweon, during 1979 to 1981. The treatments used in this study were three nitrogen fertilizing levels (120, 180 and 240kg/ha) and four different methods of nitrogen distribution (i. single application of whole amount in early Spring, ii. 50 percent each in Autumn and early Spring, iii. 50 percent each in early Spring and at begin of heading stage and iv. 50 percent in Autumn and 25 percent in early Spring and at begin of heading stage respectively). The experiment was arranged as a split-plot design with 4 replications and performed at the experimental field of the Livestock Experiment Station in Suweon, during 1979 to 1981. The results obtained are summarized as follows: 1. Date of heading stage of Festuca arundinacea was about May 21 and that of flowering stage was June 1 to 3. The optimum stage for the seed harvesting of Festuca arundinacea (var. Alta) was June 25 about 22 to 23 days after full flowering stage. Average plant height was about 127cm and the panicle length, 24cm. 2. 1000 grain weight was 2.72g and the number of panicles were 85 to 107 per square meter. 3. The mean seed wield for two years was 678.8kg/ha with the average of whole treatments and 781.9kg/ha with the best treatment (50 percent in Autumn and 25 percent in early Spring and at begin of heading stage with 240kg/ha respectively). 4. The average germination rate of harvesting seeds was 87.0 percent and it was increasing trend according to frequent application of fertilizer. 5. The average DM yield of aftermath seed harvesting was 6155kg/ha with two cut, and it was the largest DM yield from the higher nitrogen level and also from the single application in early Spring.

• Journal of The Korean Society of Grassland and Forage Science
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• v.30 no.2
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• pp.151-158
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• 2010

This study was conducted to evaluate the feed value and growth characteristics of Sasa quelpaertensis Nakai by horse grazing in the woodland of Jeju. Crude protein (CP), NDF, ADF and minerals contents at different growth stages of Sasa quelpaertensis were analyzed. The apparent digestibilities of DM, CP, NDF and ADF were determined by total collection method using 5 Jeju horses. The yield and growth characteristics of S. quelpaertensis Nakai by horse grazing were investigated. CP contents in the currentand the previous-year-sprouted leaves of S. quelpaertenisis were $16.6{\pm}1.0%$ and $12.2{\pm}1.1%$, respectively. The digestibility of DM, CP, NDF and ADF in the current-year-sprouted leaves of S. quelpaertenisis were $47.2{\pm}1.2$, $67.8{\pm}1.0$, $47.0{\pm}1.3$ and $47.1{\pm}1.1%$, respectively. The current-year-sprouted S. quelpaertenisis tended to have high nutritional values and digestibilities compared to those of the previous-year-sprouted. The dry matter yield, plant length, leaf width and density of S. quelpaertensis Nakai were clearly decreased by horse grazing. These results show that considering the feed value and growth characteristics, the natural S. quelpaertenisis Nakai can be used as a feed source for horses.