• Asian-Australasian Journal of Animal Sciences
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• v.11 no.4
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• pp.381-384
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• 1998

Twenty-three crossbred (Yorkshire $\times$ Duroc $\times$ Hampshire $\times$ Chester White) primiparous sows were used to evaluate the effects of the mineral-salt laxative in lactation diets on sow and litter performance. The sows were fed a sorghum-extruded soybean-based diet with .85% lysine, .90% Ca, .80% P, and 3.2 Mcal ME/kg. Sow body weight (p > .54) and backfat loss (p > .61), average daily feed intake (p > .42), and litter weight gain (p > .74) were not affected by the mineral-salt laxative in the diet. However, survivability of piglets was greater (p < .06) for sows with the mineral-salt laxative in their diet and, thus, number of pigs weaned was increased. As expected, fecal moisture was increased (p < .09) in sows fed the mineral-salt laxative. Apparent digestibilities of DM, N, and GE were not affected by treatment (p > .26). After weaning, stomachs were collected and scored for ulcers and keratinization using a scoring system of 0 = normal to 3 = severe. Severity of ulceration and keratinization was not significantly affected by treatment (row mean scores differ test p > .25), but scores for sows fed the diet containing the mineral-salt laxative were numerically lower than sows fed the control diet. Thus, our data indicate that sows fed the mineral-salt laxative during lactation had improved piglet survivability, greater fecal moisture, and tended to have fewer lesions in the mucosa of the stomach.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.185-192
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• 2010

Design of velocity-compounded turbine for 75ton class LRE turbopump application and pressure compounded turbine for 30ton class LRE turbopump has been performed. 1D calculation and CFD analysis were conducted in determining blade and flow passage shape of velocity compounded turbine iteratively. Finally, 23.1% improved specific power and 5% reduced weight turbine to the original design was developed. In case of pressure-compounded supersonic turbine design, rotational speed was increased by 50% and the effect of carryover ratio, 2nd nozzle installation angle, leakage flow of 2nd nozzle, and work sharing factor was studied. Final 1D design resulted 36% increased specific power and 51% reduced weight comparing to the original single-row impulse turbine. It is anticipated that nozzle flow path design will be very important for the accomplishment of expected performance of pressure-compounded turbine and nozzle shape optimization will be conducted through the CFD analysis.

• The Korean Journal of Mycology
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• v.9 no.2
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• pp.67-72
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• 1981

This study was performed to examine the cultivation of Pleurotus florida that forms pinhead between 5 and $25^{\circ}C$, on rice straw substrates in Korea. The highest yield of P. florida sporophores was obtained from the fermented rice straw substrates added 5% rice bran to the rice straw by dry weight basis at the starting of fermentation. The pile turning of materials for uniform fermenting was made three times when the temperature of the pile reached $60^{\circ}C$ during out door composting. The $60^{\circ}C$ row steam was treated 6 hrs for pasterization of the substrates in the cultivating house. The quantity of spawn affected the mycelial growth and the yield of P. florida. The optimum amount of spawn was 10% to the rice straw by dry weight basis mixed with the substrates. P. florida produced normal sphorophores from September to middle of July of the following year.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.422-426
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• 1984

According with variations in principal agronomic traits of fourteen malting barley cultivars as affected by different seeding methods and seeding rates. the analysis and interpretation of correlation coefficients and path coefficients was intended. From all treatments (seeding methods and rates), the positive significant relations detected between flowering days and maturing days, however the negative between maturing days and culm length, number of grains per spike, yields, and between 1000 grain weight and one liter weight, respectively. Direct effects on the yields were greatest by number of grains per spike in case of narrow-spaced row seeding and number of spikes per m$^2$ and number of grains per spike among others in broadcast seeding method On the other hand, indirect effects were not recognized in any treatments.

• Journal of Bio-Environment Control
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• v.8 no.4
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• pp.223-231
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• 1999

The one of basic functional conditions of suspended overhead sprayer, which is openly made use of irrigating on bedding plants in greenhouse, is to be kept the growing uniformity of bedding plants by making uniformly the spraying irrigation depending on the distribution of sprayed water. This study was performed to find out the optimum position of sector formed injection nozzle which is placed from the top of plant 0 the tip of the nozzle to keep spraying uniformity. The test of spraying distribution using a overhead sprayer, which was installed in a row of sector formed injection nozzles, was performed The measuring factor to represent spraying distribution was the water weight filled in each cup when the overhead sprayer was moving across the upside of the cups which were placed directly under the nozzles on keeping the distance from nozzle tip. The test results were as following , The standard mr of weights of each cup filled with spraying water was lower values at Position far from more than 60cm under nozzle tip. The driving speed variation of sprayer was not effected on spraying uniformity but the spraying water weight was inversely proportioned to the speed. To make best spraying uniformity, it was represented that the tip of the nozzle is positioned to keep the distance which the top of plants is placed at the second cross point of each injection sector of nozzles.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.907-917
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• 2016

This study aimed at improving the method of oil cake application in maize. The experiment was conducted during 2 years at NAS (National Institute of Agricultural Sciences) experimental field, located in Wanju-kun, Jeollabuk-do. Growth factors and nutrient use efficiency were evaluated depending on oil cake application depth, placement, and application rate. Difference in oil cake application method and depth was tested in 2012 and different placements of oil cake application were compared in 2013. Plant height, SPAD value, and dry weight of stem and corn were investigated. SPAD value, dry weight of stem and corn were significantly higher in oil cake banding treatment (OB5, 5 cm depth) as compared to others application methods, i.e. spreading (OS0), deep banding (OB10) and banding + spreading (OB5S). In addition, dry weight of stem and corn of banding treatments (OBL, OBLL) on rhizosphere and in between row (OBR) were higher than spreading treatment (OSP). Furthermore, in case of reduced application rate in additional fertilization did not decrease dry weight of corn and increased nutrient use efficiency. Therefore, it is concluded that banding application in 5 cm-depth and rhizosphere can improve growth and nutrient use efficiency in maize production.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.84-84
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• 2022

The limit of crop cultivation is moving northward due to the temperature rise by climate change. There is a problem with crop growth if early sowing is performed at a time when the temperature is low. It is difficult to secure crop productivity and cultivation stability due to the low temperature and short cultivation period. Therefore, this study was conducted to analyze the change in growth characteristics and yield of corn for grain when early sowing is performed in central region of South Korea. This experiment was conducted at experimental field of Suwon in 2021. Three varieties of corn for grain such as Kwangpyeongok, Sinhwangok, and Hwangdaok were sown at intervals of 5 days from 20 March to 15 April. The planting density at this time was sown with a row interval of 70 cm and a plant interval of 25 cm. Nitrogen, phosphoric acid, and potassium fertilizers were applied at 17.4 kg, 3.0 kg, and 6.9 kg per 10a, respectively. Phosphoric acid and potassium fertilizers were all applied before sowing and nitrogen fertilizer was applied 50% before sowing and 50% in the fifth leaf period. The corn growth characteristics and yield components were investigated. The seedling establishment rate by sowing date was in the range of 68.5~88.5%, and it showed a difference depending on the variety. The range of days from sowing to tassel and silk emergence by sowing date was 79.9~98.4 and 81.0~98.9 days, respectively. As the sowing date was delayed, the days from sowing to tassel and silk emergence decreased. The growth characteristics and yield of corn by sowing date are as follows. Plant height was the highest at 241.3 cm at the sowing on 25 March, and Stalk diameter was the thickest at 25.6 mm at the sowing on 31 March. The fresh weight per plant was the highest at 728 g at the sowing on 25 March, and the dry weight per plant was the highest at 185 g at the sowing on 31 March. Corn growth characteristics did not show a certain trend depending on the sowing date, and corn growth was more vigorous at the sowing on March 25 and 31 than the others. In the case of ear weight, it was the heaviest with 344 g at the sowing on 25 March, and filled ear length ratio showed a tendency to decrease as the sowing time was delayed. The weight of 100 grains and grain yield per 10a of maize were the highest at 36.0g and 878.7kg/10a, respectively at the sowing on 25 March. Although the growth and yield of corn for grain were good during early sowing in the central region of South Korea, it is necessary to investigate the limit temperature for early sowing of corn by examining the annual variation according to weather conditions.

• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.202-210
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• 2016

BACKGROUND: This study was conducted to determine effects of ridging systems and plastic film mulch types on growth, yield, and profitability of potato (Solanum tuberosum L.) in spring cropping using paddy field and to suggest profitable ridging system and plastic mulch type.METHODS AND RESULTS: Two potato cultivars ('Goun', and 'Atlantic') were grown at paddy field located in Gangneung in spring. For treatments, ridging systems were one-row ridge (OR) and two-row ridge (TR). Mulch types were no-mulch (NM), black plastic film mulch (BPM), and transparent plastic film mulch (TPM). Emergence of sprout was affected by the mulch types and the fastest level was shown at TPM treatment. Accumulative soil temperature during sprouting was 16.2℃ higher at TR than at OR and also higher at TPM than at BPM or NM. Stem length was not affected by ridging systems or mulch types. Leaf area index (LAI) was influenced by mulch types, while not by ridging systems. The highest LAI was shown at TR with TPM and OR of BPM. There was no significant difference in specific gravity or dry matter rate by ridging systems and mulch types. Tuber yield was significantly influenced by ridging systems and mulch types. Mean tuber weight was heavier at OR treatment than at TR and also the heaviest at TPM among mulch types. The highest marketable yield was found at OR with BPM. Based on marketable tuber yield and market price, the highest income ratio in two cultivars was found at OR with BPM and it was 20~82% higher than the ratio at TR with TPM.CONCLUSION: In spring potato cropping using paddy field, OR with BPM is better for high yield and is more profitable for farmer's income than the conventional cultivation method, TR with TPM.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.3
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• pp.196-207
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• 2016

In monsoon climates, persistent shade is a troublesome weather condition with an impact on the growth and yield of corn (Zea mays L.). We imposed 7, 14, 21, and 28 days of consecutive shade (CS) on Gwangpyeongok and P3394 corn hybrids at the beginning of the kernel filling stages. Shade had little impact on leaf area and dry matter accumulation in the stem and leaves. However, dry matter accumulation in the ear was severely reduced by approximately 28% and 53% after 14 and 28 days of CS, respectively. For the components of grain yield, 7 and 14 days of shade did irreparable damage to the number of filled kernels, the kernel number per ear row, and the percent of filled kernels, but did little damage or reversible damage after removal of the shade to the 100-grain weight and the row number per ear. Shade significantly reduced the relative growth rate (RGR) due to a decrease in the net assimilation rate (NAR). These results suggest that source activity limitation by shade during the kernel filling stages leads to the inhibition of sink activity and size. The yield of biomass, ear, and grain logistically declined as the length of CS increased. Probit analysis revealed that the number of days of CS needed to cause 25% and 50% reductions in grain yield were 3.7 and 23.1, respectively. These results suggest that the plant yield loss induced by shade at the beginning of the kernel filling stages is mainly achieved within the first 7 days of consecutive shade.

• Korean Journal of Agricultural Science
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• v.13 no.1
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• pp.1-16
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• 1986

This experiment was carried out to obtain genetic information for future corn breeding. The materials used for the study were obtained from the nationwide collection of Korean local corn lines. A total of 262 lines were used for the study of morphological characters and for the classification of lines. Results obtained are summarized as follows; 1. The days to flowering of lines ranged from 57 days to 87 days. Most lines had an average of 67 days of flowering days. 2. The number of tillers of lines showed a lot of variation among lines with 49.2% of coefficient of variation. 3. The coefficients of variation computed based on the phenotypic observation or measurement of each line were 36.1%, 27.2%, 20.0%, 16.4% and 16.3% for kernel weight per ear, 100 kernel weight, ear height, plant height and ear length, respectively. 4. Ear height, ear length, ear diameter, tiller number and days to flowering were highly and positively correlation with the plant height. Kernel size, ear size, and plant height were highly correlated with 100 kernel weight and kernel weight per ear. 5. The 262 corn lines were possibly classified into four major groups by the Euclidean distance. Group I comprised 110 lines, group II 74 lines, group III 66 lines and group IV 12 lines, respectively. Group I was characterized as having early maturity, medium plant height large kernel size and large ear size. Group II had medium maturity, short plant height, medium kernel size and small ear size. Group III had medium maturity, medium plant height, large kernel size and medium ear size. Group IV had late maturity, long plant height, small kernel size, small ear size and many tillering. 6. The plant height showed significant difference between group I and II, II and III, and II and IV group. No statistical differences were observed between group III and IV. The ear size of group I was significantly different from those of group II, III and IV. Also difference of ear size between group II and III was significant. The kernel size, 100 kernel weight and kernel weight per ear were all significantly different among all groups classified. The row number was different between group I and II. The row number of lines in group IV was significantly different with group I, II, III respectively. The number of tillers and flowering days of lines in group IV were greatly different from those of group I, II and III. 7. The corn lines collected from northwest plain regions and middle hilly regions in Korea had medium maturity, medium plant height, large ear and large kernels. The corn lines from middle eastern hilly regions had medium size of ear kernels. The corn lines from middle southern hilly regions had late maturity, small kernel size and many tillers. The corn lines from southwest plain areas had late maturity, long plant height and many tillers.