• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.515-519
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• 2009

"Sangok", is a new japonica rice variety (Oryza sativa L.), which is a midium maturing ecotype developed by the rice breeding team of National Yeongnam Agricultural Experiment Station (NYAES) in 2003. This variety was derived from the cross of Milyang 101/YR8697Acp97 (in 1988/1989 winter) and selected by combination of the bulk and pedigree breeding. The pedigree of Sangokbyeo, designated as Milyang 182 in 2000, was YR12950-B-B-B-19-2-4-2-2. It has about 79cm stature in culm length and is medium maturing. This variety is resistant to bacterial blight ($K_1$, $K_2$, and $K_3$), stripe virus and moderately resistant to leaf blast disease. Milled rice kernels of "Sangok" is translucent, clear in chalkness and good at eating quality in the panel test. The yield potential of "Sangok" in milled rice is about 5.16MT/ha at ordinary fertilizer level of local adaptability test. This cultivar would be adaptable to the southern plain of Korea below the Chungnam province by latitude from ordinary transplanting to transplanting after barley harvest.

• Korean Journal of Breeding Science
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• v.42 no.3
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• pp.272-275
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• 2010

'Geumyoung' is a new early maturing rice cultivar developed from the cross between Sambaegbyeo and Iksan423/Sangju22 at Sangju Substation, NICS, RDA, Korea in 2009. It needs about 116 days from seedling to harvest in mid-mountainous areas. This cultivar has about 72 cm long culm and 19 cm long panicle, which are similar to Odaebyeo. It has higher panicle number per plant, medium to small grains and sometimes has a few awned spikelets. It shows tolerance to cold and resistance to blast but is susceptible to bacterial blight, virus diseases, and insects and pests. Milled rice of 'Geumyoeng' is translucent with non-glutinous endosperm and medium short grain. It has about 18.0% amylose and 6.6% protein content with good palatability of cooked rice. The milled rice yield of this cultivar was 5.53 MT/ha under standard fertilizer level of ordinary transplanting cultivation. 'Geumyong' would be adaptable for ordinary transplanting cultivation in the northern plains, and northern and southern mid-mountainous areas of South Korea.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.4
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• pp.251-265
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• 2013

The emergence of social network services, is changing the foundation of human relationship formation and method of communication of individuals through sharing of free information. Social network service is a service to support or facilitate an on-line extension of off-line network among people by helping them to share personal profile. History of social network services very short. But users of the various layers is increasing rapidly and ripple effect social as a result is very large. The focus of existing research was mainly devoted to motivation of use and acceptance of social network services. Currently the use of SNS was maturing. Thus, in-depth research on the use pattern of SNS users is needed. The purpose of this study is that, for Facebook in social network services, to analyze the changes in the initial stage of use, medium-term, usage patterns at the current time. Results of the study by analyzing the characteristics of the change in the pattern of usage of user of Facebook, it can be used as basic materials for SNS researchers and service provider.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.344-352
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• 2019

Drought stress caused by global climate change is a serious problem for rice cultivation. Increasingly frequent abnormal weather occurrences could include severe drought, which could cause water stress to rice during the seedling stage. This experiment was conducted to clarify the effects of drought during the seedling period on yield and quality of rice. Drought conditions were created in a rain shelter house facility. The drought treatment was conducted at 3, 10, and 20 days after transplanting. Soil water content was measured by a soil moisture sensor during the whole growth stage. In this study, we have chosen 3 rice cultivars which are widely cultivated in Korea: 'Haedamssal' (Early maturing), 'Samkwang' (Medium maturing), and 'Saenuri' (Mid-late maturing). The decrease in yield due to drought treatment was most severe 3 days after transplanting because of the decrease in the number of effective tillers. The decrease in grain quality due to drought treatment was also most severe 3 days after transplanting because of the increased protein content and hardness of the grains. The cultivar 'Haedamssal' was the most severely damaged by water stress, resulting in about a 30% yield loss. Drought conditions diminished the early vigorous growth period and days to heading in early-maturing cultivars. The results show that drought stress affects yield components immediately after transplanting, which is a decisive factor in reducing yield and grain quality. This study can be used as basic data to calculate damage compensation for drought damage on actual rice farms.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.4
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• pp.440-448
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• 1989

The present experiment was conducted to investigate the effects of seeding date on agronomic characters including seed weight of soybean (Glycine max (L.) Merr.) at Sunchon, the southern coastal area of Korea. One hundred eighteen native and improved varieties were used in this study. As the seeding date was delayed, the number of days to flowering for the cultivars was reduced. This trend was more obvious in late maturing cultivars(LMC) than in early and medium maturing cultivars (EMC and MMC). Late seeding also resulted in decrease in the number of leaves, stem length, and number of nodes. The heaviest seed weight was obtained with EMC and MMC planted on May, and seed weight decreased with delayed seeding date. Seed weight was positively correlated with number of days to flowering, number of total leaves at flowering, stem length and number of nodes on main stem at maturity. Based on seed weight the cultivars was classified into five types: Type I; Seed weight of the cultivars decreases with delayed seeding date. Type II; Seed weight of the cultivars does not vary with seeding date. Tyep III; Seed weight of the cultivars increases with delayed seeding date. Type IV; Seed weight of the cultivars increases when the seeding date approached the appropriate seeding date, but decreases thereafter. Type V; The reversed type IV. Type I, II, III, IV and V occupied 37, 16, 17, 10 and 20％ of the tested cultivars, respectively.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.1
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• pp.26-39
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• 2013

Yield reduction in major cereal grains seems unavoidable with the existing cropping systems under the projected climate change in Korea. Crop models were used to predict the effects of planting date shift on grain yields of rice, winter barley and soybeans at 64 agroclimatic zones in Korea. The shift of planting date by 7, 14, and 21 days before and after the recommended planting dates were incorporated in DSSAT experiment files to simulate growth, development and grain yields of major cereal crops. These included 3 rice cultivars representing early-, medium- and late-maturity groups, 1 winter barley and 1 soybean cultivars. Partial mitigation in yield reduction was found with earlier planting in the early maturing rice cultivar and with delayed planting in the late maturing rice cultivar under the RCP8.5 projected climate change in Korea. Additional yield increase in winter barley was expected by earlier planting treatments. Soybean showed a positive effect on grain yield with earlier planting. However, the rate was much lower than the case with winter barley and delayed planting caused yield reduction.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.256-262
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• 2012

This experiment was conducted to determine the agronomic characteristics for selection of the excellent barnyard millet and the herbicidal response for their weediness prevention in paddy rice. IT170609, IT195422 and EV2012 have produced more dry matter compared to other barnyard millets tested. In varietal characteristics by heading date, IT170609 showed medium maturing type and IT195422 and EV201 had late maturing type. The germination rate of IT170609, IT195422 and EV2012 on temperature was higher than Echnochloa oryzicola of native species, and it was definitely distinctive at 20 and $25^{\circ}C$. In the herbicidal response for their weediness prevention in paddy rice, imazosulfuron+benzobicyclone+penoxsulam SC showed control effect the extend of over 90% to IT170609, IT195422 and EV2012. Cyhalofop-butyl EC, penoxsulam SC and metamifop EC were very effective by 6~7 leaf stage of barnyard millets tested.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.4
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• pp.309-316
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• 2004

This experiment was carried out to assess the growth and development of five rye(Secale cereale L.) cultivars based on the Feekes scale in relation to sowing date at the Experimental Livestock Farm, Seoul National University(SNU), Suwon from 30 September 2001 to 4 May 2002. The experiment was conducted in split plot design with three replications. The main plots consisted of two sowing date such as early(30 September) and late(15 October). The subplots consisted of rye cultivars of five different maturity groups such as 'Kodiak', 'Koolgrazer', 'Danko', 'Homil22' and 'Olhomil'. The plant height of early sowing rye cultivars was higher than that of late one. Among the rye cultivars tested, plant heights of early maturing cultivars were higher than those of the other cultivars. The tiller number at early sowing(48.0) was higher than that of late(24.3), however, late maturing cultivars were higher than those of the other cultivars among the rye cultivars tested. Growth and development in the early sowing were generally three days earlier than those of late sowing cultivars. Growth and development in 'Olhomil' rye cultivars was earlier than 'Danko' rye cultivars when sown in early, but 'Olhomil' and 'Koolgrazer' rye cultivars showed an early maturity than 'Danko' rye when sown in late. Therefore, the developmental stages of winter rye cultivars could be categorised the following maturity; 'Olhomil' and 'Koolgrazer' are early in maturity, 'Homil22' is medium, and 'Kodiak' and 'Danko' are late in maturity.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.4
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• pp.327-337
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• 1996

A field experiment was conducted at SNU Experimental Livestock Farm, Suweon in 1995 to determine effect of planting date on forage performance of wm hybrids of four different maturity groups. A split-plot design replicated three times was used, with com hybrids representing four maturity groups (115, 118, 121 and 125 days) being the main plots and planting dates (3124, 415, 415, 425, 515 and 5/15) the sub-plots. 1. Days to emergence and percent emergence from the March 24 planting were, on the average, 36 days and 58%, respectively, but those from the April 5 to May 15 planting averaged 12 days and 92%, respectively. 2. Plant and ear heights increased gradually as the dates of planting were delayed except the May 15 planting, however, percent ear was decreased as the dates of planting were delayed. There was a trend for the mean lodging percentage of the hybrids to be higher as the planting date was delayed. 3. The 115-and 118-day mediumearly maturing hybrids harvested on August 18 produced silages with a dry matter content between 27 and 30% at all planting dates except the May 15 planting, while the 121-and 125-day medium-late maturing hybrids produced silages with a dry matter wntent less than 27% regardless of any planting dates. 4. There were no significant differences in mean dry matter yield among the hybrids, but significant mean TDN yield differences were found. The 115-, 118- and 125-day hybrids had significantly higher mean TDN yield than the 121-day hybrid. There were significant differences in mean dry matter and TDN yields among the planting dates. The mean dry matter and TDN yields from the April 5, 15 and 25 plantings were significantly higher than those of other plantings, however, there were no significant differences in mean TDN yield among the April 5, April 15 and April 25 plantings. No significant planting date $\times$ maturity interactions were found for both the dry matter and TDN yields. 5. Mean stover NDF and ADF contents of the 115- and 118day hybrids were higher than those of the 121- and 125-day hybrids, but the reverse was true for mean stover IVDMD and RFV. Mean stover NDF an ADF contents increased with earlier plantings, but mean stover IVDMD and RFV increased when planting was delayed. Results of this experiment indicate that for corn planting in central and northern areas of Korea, early to mid-April may be the right time with the 115-to 118-day maturity hybrids when silage making before August 20 is taken into consideration.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.1
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• pp.39-44
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• 2001

Growth characters and productivities of corn varieties were compared to provide the basic data to the famers that in order to select the good corn varieties at Deakwanryoung district of Korea. Currently cultivated 8 recommended corn varieties and Suwon 19ho as check variety were used in this experiment and experimental design was randomized complete block with three replications. Resarch results obtained at Deakwanryoung branch (sea love 800m) of National Livestock Research Institute in 1999 are summarized as follows. Culm lengths of DK501 and GL4899 among corn varieties were shorter as 180cm and 198cm, respectively and rest of varieties were more or less 230cm and no difference among varieties. Inflorescence height was lower in varieties showing low culm length, and inflorescence heights of PK3525 and DK729 were higher about 10～15cm than those of other varieties. Stem diameters of all varieties except DK501 were thicker compared to check variety, Suwon 19ho and P3144W was thickest. Leaf numbers of late maturing DK729 and G4743 were higher as average 12 and 12.3 per plant, respectively. Silking dates among varieties were ranged from August 10 to 20 showing 10 day difference and DK501 was earliest as August 10 and G4743 was latest as August 20. Ear rates of early silking varieties were more than 46% and late silking varieties were less than 40%(P>0.1). Dry matter and TDN yield of P3351 was highest as 24,710 and 17,470kg/ha respectively, and DK729 and G4743 were second and third in order. In conclusion. early and medium maturing variety. P3352 with high yield and good growth characters was desirable at Deakwanryoung district of Korea.