• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.27 no.4
• /
• pp.462-469
• /
• 1982

Since 1962, varietal development and dissemination for summer upland crops have been actively initiated by the Crop Experiment Station, Office of Rural Development, Suweon, Korea. The major breeding objectives of soybeans have been to develop varieties which are early maturing, disease resistant, and adaptable to late planting for after-barley cropping. Development of eleven new soybean varieties including Hwangkeumkong, Jangyeobkong, Danyeobkong, and Kwangkyo has greatly increased the soybean yield throughout country. For com, after development of Hwangok #2, a synthetic, in early 1960's, nine corn hybrids-single crosses, double-crosses, and three-way crosses-such as Jecheon-ok, Hoengseong-ok, Kwangok, Suweon #19, etc., have been disseminated mainly to Kangweon province, a major corn producing area in Korea, and drew up the yield over 4 tons per hectare. The major breeding objectives of sweet potato have been to develop varieties which have high starch content and root yield. Hwangmi, Hongmi, and Shinmi are three sweet potato varieties developed and disseminated by the Crop Experiment Station, Office of Rural Development and are grown most widely in Korea. Most of researches on cultural practices of upland crops have begun on a full scale from early 1960's. In soybeans, for example, no fertilizer but for barley was applied although the effects of phosphate and potassium fertilizers were great on soybeans in after-barley soybean croppings. The effects of heavy application of phosphate and calcium fertilizers on soybeans in newly reclaimed soils were recognized. Recently a mixed fertilizer for soybean (N; 40, P:70, K:60 kg/㏊) was developed and sold for soybean growers. The optimum planting densities of 220, 000 plants/ha in full-season cropping and 330, 000 pts/ha in after-barley cropping of soybeans were known from repeated experiments. For higher yield, a means of cultural practices such as transplanting-pinching, direct planting-pinching, and hilling-up, etc., were developed along with barley-stubble planting with no tillage and integrated herbicide application for labour savings. For sweet potato, cultural practices for planting date, harvesting date, fertilizer, and planting density were fully established. For early marketing, a technique of vinyl-mulching on sweet potato has also fully developed. For com, planting density of 37, 000 pts/ha in early 1960's has been changed to 55, 000 pts/ha for grain production and 67, 000 pts/ha for silage. The amounts of fertilizers have also been changed from 120-120-120kg/ha (N-P-K) in early 1960s to 180-150-150 kg/ha. These increases in number of plants per unit area and fertilizer levels have resulted in greater production for both grain and silage. At the same time, the production techniques of F1 seeds have also improved.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.56 no.3
• /
• pp.192-198
• /
• 2011

Establishment of mechanized soybean production system without herbicide is required for organic soybean production in recent. Effects of mechanized soybean planting with partial tillage between growing rye living mulch, which was sown in April or early May, on weed suppression, soybean early growth and yield were investigated with different rye sowing dates and locations in 2007 and 2008, respectively. Effect of rye living mulch on weed suppression at 40~50 days after soybean planting was high as much as 70~90% regardless of rye sowing dates. In particular, a strong suppression effect on the occurrence and growth of Echinochloa crus-galli which occupied 60~80% of total weed biomass was observed. Rye living mulch sown on April 9, of which biomass was more than that sown on April 27, inhibited soybean early growth severely and reduced soybean grain yield in 2007. However, soybean grain yield was no t reduced despite suppression of early growth of soybean plant by living mulch sown during from late April to early May compared with conventional planting. Rye sowing before late April was not proper considering tendency of weed occurrence in spring because of unfavorable changes in weed suppression, early growth and grain yield of soybean according to amount of living mulch.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.53 no.3
• /
• pp.326-332
• /
• 2008

This study was conducted to evaluate an early-maturing rice cultivars adaptable to early transplanting cultivation in Yeongnam plain area. High temperature during the ripening stage of paddy rice under the early-transplanting cultivation in Yeongnam plain was to influence in several agronomic traits such as number of spikelet, ripening ratio, grain appearance of milled rice, and yield. 'Gounbyeo' and 'Junghwabyeo' were better than the others in grain appearance of milled rice and ripening ratio, but their yield potential were lower than that of the other varieties. Moreover, 'Gounbyeo' and 'Junghwabyeo' showed high ratio of broken rice. 'Unkwangbyeo' was the highest in yield and eating quality among the tested varieties, but also high percentage of white core and belly in milled rice. Therefore, in order to recommend those cultivars to farmers, it should be needed to establish an optimal cultivation method, such as transplanting density, fertilizer application, and harvesting time, etc. consequently, it should also be required to develop a new varieties with high ripening capability under high temperature condition.

• Korean Journal of Organic Agriculture
• /
• v.4 no.2
• /
• pp.79-85
• /
• 1995

This experiment was carried out to broadcating effect of chitosan solution levels on dry matter production in Ladino clover(Trifolium repens). Chitosan solution was applie at 6 levels, 0%, 0.01%, 0.05%, 0.1%, 0.5% and 1.0%, respectively. The results obtained were summarized as follows ; 1. The dry matter yields of chitosan treatment plot were about 30%~63% more than the dry matter yield of control plot in all cuts. 2. Total dry matter yield was produced by 659.7kg/10a at levels of 0.05%, it was significantly higher than other chitosan solution levels. 3. The predictable highest yield and economic yield of Ladino clover could be obtained at 0.05% and 0.01% solution levels, respectively. 4. The relative dry matter yields for total dry matter yield were 66.7%, 18.3% and 15.0% at 1st, 2nd and 3rd cut, respectively. Chitosan application at early spring was affected to increasing the dry matter yield of 1st cut.

• Journal of the Korean Society of Tobacco Science
• /
• v.11 no.2
• /
• pp.115-126
• /
• 1989

This study was conducted to determine the time and methods of predicting tobacco yield, by studying the relationship of yield components to yield. 1. The relationship between each position in leaf dry weight and approached gradually each other and also correlation coefficient of top leaf was higher than that of lower leaf. The leaf dry weight per plant was highly correlated with leaf area from 16th leaf position on stalk. Leaf dry weight of each leaf position on stalk was highly correlated with leaf dry weight per plant at 14 to 16th leaf position. 2. The correlation coefficient between leaf dry weight and leaf area per plant was higher at the late growth stage than at the early growth stage, and higher between the near stages. Correlation coefficient between leaf dry weights was higher than that of leaf areas. 3. Flue-cured tobacco yield be estimated from leaf dry weight per plant at 50 to 55 days after transplanting. 4. Air-cured tobacco yield could be predicted from leaf dry weight per plant at 60 days after transplanting.

• IE interfaces
• /
• v.20 no.1
• /
• pp.87-93
• /
• 2007

Burn-in is an engineering method for screening out products containing reliability defects which would cause early failures in field operation. Previously, various burn-in models have been proposed mainly focused on the trade-off of shop repair cost and warranty cost ignoring manufacturing yield. From the view point of a manufacturer, however, burn-in decreases warranty cost at the expense of yield reduction. In this paper, we provide a general model quantifying a trade-off between product yield and reliability, in which any defect distribution from previous yield models can be used. A profit function is expressed in burn-in environments for determining an optimal burn-in time. Finally, the method is illustrated with gate oxide failures which is an important reliability concerns for VLSI CMOS circuits.

• Asian-Australasian Journal of Animal Sciences
• /
• v.29 no.4
• /
• pp.580-585
• /
• 2016

The objective of this study was to determine cow characteristics and farm management factors during the dry period associated with early postparturient intramammary infection (IMI) and subsequent clinical mastitis (CM). Data were collected three times: before drying off (P1), during the dry period (P2), and 5 to 14 days after calving (P3), using questionnaires and farm investigation. Milk samples were aseptically collected for bacterial identification at P1 and P3. Factors associated with IMI and CM were analyzed using multiple logistic regression models. The final model showed that IMI in early postpartum was significantly associated with full insertion of dry cow antibiotic, dry cows in barns with a combination of tie and free stalls, body condition score (BCS) in dry period and after calving, and milk yield before drying off. For IMI cows, factors significantly associated with clinical expression of mastitis were having daily barn cleaning, teat disinfected with alcohol before administration of dry cow therapy, BCS before drying off, milk yield before drying off, and days in milk at drying off. In conclusion, both cow and farm management factors are associated with the IMI rate and subsequent expression of clinical signs of mastitis in early postpartum cows.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.6
• /
• pp.534-539
• /
• 2003

The yield and quality characteristics of three rice varieties(Seojinbyeo, Ilpumbyeo, and Chuchungbyeo) in reclaimed saline paddy field were investigated under different cultural practices, three transplanting times (May 15, May 30 and June 15) and four harvest times (40, 50, 60 and 70days after heading) in order to obtain basic information for the production of high quality rice. Brown rice yield of three rice varieties were significantly higher in early and medium than late season cultivation. The protein content of milled rice showed high interaction effect between transplanting time and harvest time. Palatability values of Seojinbyeo and Ilpumbyeo were significantly higher in late than medium season cultivation, but Chucheongbyeo did not show any difference in its palatability value by different transplanting time. The palatability values of three rice variety was the highest in the harvest at 40 days after heading. The grain yield of three rice varieties were higher in early and medium than late season cultivation, whereas palatability values of three rice varieties were significantly higher in the early and late season cultivation than medium season cultivation. The palatability value measured by rice taster showed a highly negative correlation(r=$0.43^{**}$) with cumulative air temperature during ripening period.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.17 no.2
• /
• pp.101-109
• /
• 1997

Nine oat(Avena sativa L.) cultivars have been recommended as the govemment recommended forage cultivars since 1984, however, their forage performance and quality have mostly been tested at two locations, such as Suweon in the Middle Northwestem Coast Region and Sunghwan in the Middle Southwestern Coast Region. Therefore, the objective of this experiment was to retest the forage performance and quality of six government recommended oat cultivars at five scattered locations, such as Icheon, Suweon, Sunghwan, Keongsan and Kwangju fom 1992 to 1994 with the intention of improving recommendations to dairy farmers. Among the oat cultivars tested, "West" was the highest yielding cultivar at all locations in 1992-94, but the lowest yielding cultivars varied by location and year. At both Icheon and Suweon, "Cayuse", "Magnum" and "Foothill", at Sunghwan, "Cayuse" , "Ensiler" and "Foothill", at Keongsan, "Magnum", "Cayuse" and "Swan", and at Kwangju, "Cayuse", "Magnum" and "Cayuse", were the lowest yielding cultivars in 1993, 1994 and 1995, respectively. At all locations in 1992-94, "West" and "Swan" were the most advanced in growth stage, but "Cayuse", "Foothill", "Magnum" and "Ensiler" were the latest developing cultivars among the oats. Differences among the oat cultivars for the three-year mean NDF, ADF and IVDMD were small and inconsistent, but forage quality of the oats was generally lowest in the early developing cultivars and highest in the late developing cultivars. The govemment recommended oat cultivars tested were generally well adapted across the country, however, in forage production situations in the fall where high yield is more important, early maturing oat cultivars might be preferable to late cultivars because they have higher forage yield earlier in the fall.ction situations in the fall where high yield is more important, early maturing oat cultivars might be preferable to late cultivars because they have higher forage yield earlier in the fall.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.11 no.3
• /
• pp.145-152
• /
• 1991

This experiment was carried out to investigate the effects of liming, manure application, and inoculation with Rhizobium on the early growth, nodulation, seedling establishment, winter survival, and forage yield and quality of alfalfa(Medicago sativa L.) at the Experimental Livestock Farm, College of Agriculture, Seoul National University, Suweon in 1985 and 1986. The results obtained are as follows: 1. Seedling vigor and nodule formation of alfalfa at early stage were the best in the treatments of liminginoculation( L1) and liming-manure-inoculation(LM1). 2. Seedling establishment was not significantly affected by the treatments of liming, manure application, nodulation and the combination of these. 3. The LI and LMI treatments showed the highest winter survival of 94.3 and 83.5%, respectively, but the lowest winter su.rvival of 55.9 and 58.5% was found in no treatment(None) and inoculation( I ), respectively. 4. No differences in crude protein(CP1, acid detergent fiber(ADF) and neutral detergent fiber(NDF) contents were found among the treatments. 5. There were significant differences in the total dry matter yield of alfalfa among the treatments. The total dry matter yields of 10,618, 11,830, 11,855 and 13,456 kg/ha from the treatments of L, LM, LI and LMI, respectively, were significantly higher than those of None, M and I treatments. 6. Based on the results of the experiment, it appears that the dry matter yield of alfalfa could be enhanced by the treatments of liming with Rhizobium inoculation and also liming, manure application and Rhizobium inoculation as a practical method.