• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.360-360
• /
• 2008

Steelmaking industry is widely known to use a lot of water and same amount of wastewater is generated. Although toxicity of wastewater from Steelmaking industry is low, it contains an amount of various organic materials and Fe-Oxides. It is important to recycle the wastewater because of water shortages and water pollution. In general, large-scale equipment is necessary to process the wastewater. On the other hand, superconducting high gradient magnetic separation (HGMS) system can process the wastewater in the small space. Superconducting HGMS system that had a purpose to purify the wastewater was assembled. Cryo-cooled Nb-Ti superconducting magnet was used for magnetic separator. This system can operate continuously because contaminated filters can keep on returning after cleaning. The various magnetic seeding reactions were investigated to increase the reactivity of coagulation. Filter cleaning system was developed to decrease the quantity of clean water. This research was supported by a grant from Korea Electrotechnology Research Institute, Republic of Korea.

• Korean journal of applied entomology
• /
• v.36 no.1
• /
• pp.55-66
• /
• 1997

This study was conducted to analyze arthropod community patterns in small rice fields associated with different planting methods (water seeding, drill seeding, and hansplanting) in Suwon and Icheon in 1994. Total 15 orders and 45 families of arthropods were collected. The arthropod community was analyzed using guild categories. The arthropods were found in the order of 'natural enemy>pest(phytophage)>non-pest' in their densities in all sites. The pest (phytophage) species were mainly Homoptera and dominated by Delphacidae (Nilaparvata lugens Stsl, Sogatella fircifera Horvath and Laodelphax striatellus Fallen) and Cicadelidae (Nephotettir cincticeps Uhler). They constituted >80% of pest abundance. Differences in pest abundance were not found among rice fields associated with different planting methods. Spiders were the most dominant group in the natural enemy and constituted >90% of natural enemy abundance. Hunting spiders constituted >SO% of spider abundance and were dominated by Pirata subpiraticus Bos. et Str. (Lycosidae). Pacliygnatha clerki Sundevall (Tetragnathidae) was a dominant species in webbing spiders. No differences were found in species richness and diversity in spider community among rice fields associated with different planting methods. The nonpest species were mainly Diptera and occurred abundantly in early growing season and decreased drastically as rice development proceeded. The non-pest abundance was higher in direct seeding sites than in transplanting site, and especially abundant in a drill seeding site.

• Korean Journal of Environmental Agriculture
• /
• v.18 no.3
• /
• pp.229-235
• /
• 1999

To identify the differences on plant growth and yield of two rice cultivars among direct water-seeding methods broadcasting on flooded paddy surface(BF), drilling on flooded paddy surface(DF), and puddled-soil drill seeding(PD) under markedly different weather condition between 1995 and 1996. The mean air temperature for duration from May to June, early growth stage of rice in 1995 was lower $1{\sim}3^{\circ}C$ than that in normal or 1996. In 1995 the respiratory consumption index during panicle formation stage and early ripening stage was higher than those of in 1996 or normal year. Number of seedling stand among the methods of direct seeding rice appeared slightly higher in order of BF>DF>PD. Properly in Nonganbyeo, the number of seedling stand was much low in 1995 compared with in 1996. The leaf area index and shoot dry weight at early growth stage of rice plant and culm length at mature in 1995 were larger in direct water seeding rice than those of machanical transplanting rice, but in 1996. Faster ripening speed and shorter ripening period of rice crop appeared in 1996 compared to in 1995. It was due to higher growing degree-days, sunshine hours and solar radiation during rice growing season in 1996. Dongjinbyeo rice showed higher yield than Nonganbyeo which had lower ripened grains especially in 1995.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 1992.05a
• /
• pp.72-73
• /
• 1992

• Korean Journal of Weed Science
• /
• v.8 no.1
• /
• pp.28-32
• /
• 1988

The effects of standing water and cultivation frequency on emergence of Echinochloa glabrescens Munro ex. Hook were determined at varied seeding methods under simulated field conditions for 4 months. In soil-incorporated seeding method total emergence for 4 months was highest in saturated condition followed by 4, 2, and 8cm standing water, whereas total emergence of seeds sown at the soil surface was highest at 2cm standing water followed by 4cm, saturated soil, and 8cm standing water. Within 2 weeks the emergence was highest at 4cm and lowest at 2cm standing water with the soil-incorporated seeding, but the seeds sown at the soil surface with 2cm standing water resulted in the highest emergence. Ratio of emergence within 2 weeks over total emergence during 4 months was lowest at 2cm standing water in the soil incorporation, indication that 2cm standing water would be the critical water level for E. glabrescens. Since most of the seedling was emerged within 2 weeks just before cultivation, the emergence pattern was little affected by cultivation at each standing water level.

• Korean Journal of Weed Science
• /
• v.12 no.3
• /
• pp.230-260
• /
• 1992

The paper was reviewed the research results on weed dynamics and effective control methods in direct-seeded rice crop. Direct seeding method resulted in drastic increment of weed growth compared to transplanting method and also changed in troublesome weed flora. Two to three fold more weeds were harvested at the direct seeded rice and weed flora of dominant species shifted toward $C_4$type grass weeds. Some of the important troublesome weeds in direct seeded rice were Echinochloa crus-galle, Oryza saliva ssp spontanea, Leptochloa chinensis. Setaria viridus. Digitaria adsendens, Sesbania exaltata, Aeschynomene indica, Algae, etc. Yield loss due to weed competiton was about 40-60% for water-seeded and about 70-100% for dry-seeded rice while these for transplanted rice were about 25-35% for mechanical transplanting and about 10-20% for manual transplanting, respectively. Integrated weed management concept was neede to approach weed control effectively. Several cultural technologies were very effective to suppress the weed growth. These were tillage operation, water management, seeding date and seeding rate. Crop residues of barley, rice, wheat, oat and italian ryegrass were also effectivly suppressed the paddy weeds particularly to Potamogeton distiuctus, a perennial broadleaf weed. A pathogen of Epicoccosorus nematosporus identified from Eleocharis kuroguwai was an excellent potential bioagent to control the most troublesome perennial sedge weed of E. Kuroguwai without arising any detrimental effect. The herbicidal efficacy of this pathogen was as high as bentazon herbicide. Plant growth regulator of paclobutrazol (pp-333) was another possible alternative to reduce the herbicide use. In current, herbicide exhibited the most conspicuous results to control weeds in direct-seeded rice even though the application technologies were not fully established. Recommendations for herbicide application were suggested for in both water-and dry-seeded rice in USA, Japan and Korea, respectively. To make better and comprehensive recommendations further studies on weed ecology and herbicide development were emphasized.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.47 no.3
• /
• pp.221-225
• /
• 2002

This study was conducted to identify the effects of slow release fertilizer (LCU) on ridge direct seeding on dry paddy of rice as an irrigation water-saying cultural system. During 1999-2000, a series of experiments was carried out at field (Chonbuk series) of the National Honam Agricultural Experiment Station, RDA using Dongjinbyeo. Plant height and culm length during the total growth duration were the longest and panicle umber per $m^2$ was the highest in 100% LCU application rate. Leaf area index and top dry weight were the highest in the 100% LCU application rate. They increased as more LCU was applied. Nitrogen uptake was the highest in 100% LCU application, and N use efficiency was the highest in LCU 60% + FP (fertilization at panicle formation stage) 20% application. Milled rice yield was 7% higher in 100% LCU application rate than that of conventional N application. Ripened grain rate and 1,000-grain weight of brown rice did not differ, but panicle number per $m^2$ and grain number per m2 were the highest at 100% LCU application.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.41 no.2
• /
• pp.157-167
• /
• 1996

The method of direct seeding on flooded paddy surface in rice is known to be the most labor saving cultural practice in rice. However, this method has a problem in practical use such as severe lodging occurring at the reproductive growth stage. The objectives of this study were observated degree of field lodging and variation of lodging-related characteristics with different seeding dates. The number of seedlings per m$^2$ were from 91 to 144 plants, and seedling ratios were from ranged from 61.7% to 91.8%. Days from seeding to flowering were shortened from 5 to 15 days by the later seeding dates. Heading dates of Ilpumbyeo, Seoanbyeo, Daecheongbyeo and Donjinbyeo on June 9 showed slightly elapsed on the critical stable heading time from, August 28 to 29. The culm length was effective in longer clum varieties than semidwarf varieties. The degree field lodging (degree of lodging: 0~9< 9 : complete lodging) in Obongbyeo and S101 with semidwarf varieties were 0.17, whereas 1.25 in Dongjinbyeo with long culm. The lodging resistant varieties and later seeding dates shortened the length of fibrous in the clum, and thickened fibrous in the clum, respectively. Obongbyeo and Sl0l showed stronger resistance to field lodging. The lodging resistant varieties, Obongbyeo and Sl0l, showed lower values of lodging index from 1.03 to 1.15 than those of lodging susceptible varieties, Daecheongbyeo and Palgongbyeo ranged from 1.42 to 1.70. Bending moment with leaf sheath were greater in lodging resistant varieties (Obongbyeo and Sl0l),1510.0~1930.4g.cm, than those in the lodging susceptible varieties (Daecheongbyeo and Palgongbyeo), 1127.2~1287.6g.cm.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.7 no.1
• /
• pp.35-46
• /
• 2005

This research was conducted to improve and establish Bokto direct seeding technology use of silicate in rice. Bokto direct seeding technology has recently released to alternative new method for transplanting method of the rice plant. In recent rice production has serious problem due to higher cost and labor shortage in Korea. In particular rice has been faced on open market to internationally due to WTO, FTA agreement etc. Thus rice growers in Korea have been more concentrated on cost reduction using by direct seeding technology such as dry seeding and water seeding while those methods have severe constraints like poor seedling, more weed occurrence, lodging and poor grain quality. In recent a new technology for improvement of these problem has released to farmer's field and proven to alternative rice growing technology of transplanting. In this technology there was additional application of silicate which has known as soil improvement and this research was obtained in the following results. At the application of silicate, sand, and soil there was high in seedling establishment by 90~100% in pot experiment but there was 55.0% seedling stand of the untreated control. Under dry condition seedling stand was 0% at the untreated control while 65~100% high in application of silicate, sand, and soil. Meanwhile, under rainy condition untreated control there was 85% of seedling stand but soil application was 20% of seedling establishment due to blocking of oxygen and physical soil blockage.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.62 no.1
• /
• pp.9-15
• /
• 2017

Germination characteristics, seedling emergence, and early seedling growth of iron-coated rice seeds, cultivars Daebo and Samdeokbyeo, under different water depths were compared with those of non-coated seeds (control) and the results evaluated to obtain basic information for establishing stable seedlings in direct water seeding. The total germination percentage of the two seed treatments was similar, but iron-coated seeds had slightly faster germination and shorter mean germination time than non-coated seeds. Water absorption rates of iron-coated seeds were lower than that of non-coated seeds during seed germination. The germination percentage of the two iron-coated rice seed cultivars showed a significant decline of 15-22% after one year of storage under natural conditions. The seedling emergence percentage and uniformity of the two rice cultivars were significantly higher in the iron-coated seeds at 1-13 cm water depths but the percentage of floating seedlings was lower in iron-coated seeds than in non-coated seeds. The iron-coated seeds had a high seedling emergence percentage of 91.3-93.3% at all flooding depths whereas the non-coated seeds had a significantly low seedling emergence percentage of 57.7-71.7% at a water depth of 13 cm. Moreover, the shoot dry weight and seedling health score of iron-coated seeds were significantly higher than those of non-coated seeds, while root dry weights were similar in iron-coated and non-coated seeds, regardless of water depth. These results suggest that iron-coated seeds are more appropriate for stable seedling establishment in direct water seeding than are non-coated seeds.