• Korean Journal of Environmental Agriculture
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• v.9 no.1
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• pp.47-52
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• 1990

Metaldehyde Granule (6%) was sprayed 7, 15 and 30 days before harvest at the level of 0.3kg AI/l0a to evaluate metaldehyde residues on the inner and outer part of chinese cabbage. Roots of chinese cabbage were also analyzed. Results were as follows : 1. The amount of free acetaldehyde in chinese cabbage was 0.02-0.18ppm. 2. It was shown that metaldehyde residues in the leaf and root of chinese cabbage increased as the number of treatment increased and treatment period decreased. 3. The metaldehyde residue range in the leaf was in the range of 0.11-1.4ppm 4. The difference of metaldehyde residue on the inner and outer part of chinese cabbage was in the range of 0.01-0.6ppm and the residue on inner parts was slightly higher than outer part. 5. The metaldehyde residue in the root was in the range of 0.04-0.63ppm.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.4
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• pp.325-329
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• 1984

This study was conducted to evaluate the performance of a miniaturized hydrometer of clay content determination in the field. The performance of the miniaturized hydrometer was compared to that of 152H hydrometer and pipette methods. Statistical analysis of the results showed the possibility of using the miniaturized hydrometer for clay content determination in the field.

• Korean Journal of Weed Science
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• v.32 no.1
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• pp.52-56
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• 2012

The occurrence of sulfonylurea-resistant weeds has recently increased in Korea. A survey was performed to investigate major paddy field weeds and frequently used herbicides in Gangwon province, Korea in order to establish a system to efficiently control herbicide-resistant weeds. The dominant paddy field weeds included Monochoria vaginalis (14%), Sagittaria trifolia (14%), Scirpus juncoides (13%), and Echinochloa spp. (13%), and the most widely used herbicides were oxadiazon 12% EC (27%), butachlor 5% GR (20%), oxadiargyl 1.7% EC (16%), and benzobicyclon+imazosulfuron+pyriminobac-methyl 6.1% SC (14%) in Gangwon province, Korea. Many paddy rice growers considered Scirpus juncoides, S. trifolia, Echinochloa spp. and M. vaginalis as herbicide-resistant weeds. An extensive research deserves to be conducted to monitor occurrence of herbicide-resistant paddy weeds in Gangwon province, Korea.

• Journal of Biosystems Engineering
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• v.31 no.2 s.115
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• pp.108-114
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• 2006

This study was conducted to design and fabricate a controller for variable-rate application of granular fertilizer based on physical and chemical information, to analyze the performance of the controller and characteristics of a discharger. The result of the study are summarized as follows: 1. The charge ratios of discharger by accumulation heights of fertilizer in hopper were examined, and the variations in charge ratio were $72.58{\sim}93.33%$ and $63.14{\sim}94.42%$ for the fertilizers Super 21 and Sinsedae, respectively. The charge ratio also decreased as the rotational speed of discharger increased. 2. The coefficient of variation of discharge amount by rotational speed and discharge time of discharger were in the range of $2.94{\sim}11.23%$ and $2.82{\sim}10.80%$ for the fertilizer of Super 21 and Sinsedae. Except the rotational speed of 12 rpm, the coefficient of variation for discharge amount were relatively small with 4% more or less 3. In order to evaluate the rotational speed of discharger, the control signal in the range of $0{\sim}5V$ was subdivided into the 50 steps by 0.1V. The regression equation for the rotational speed of discharger was Y=55.984X-79.174(X: input voltage, V, Y: discharger speed, RPM) and the $R^2$ was 0.99. 4. In order to evaluate the performance of the controller for variable-rate application of granular fertilizer, settling time to unit step input was examined. The settling time varied from 0.8sec to 1.4 sec.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.1
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• pp.37-42
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• 1978

In other to find out the effect of N.K compound fertilizers, 17-0-17 and 17-0-14, a field experiment was conducted with rice (Oryza sativa L. Akibare). Results obtained were summarized as fellows: 1. The effect of compound fertilizer on the yield of paddy and nutrient uptake was not much differed from that of Urea and Muriate potassium. 2. It seemed that the compound fertilizer, 17-0-17, was rather pertinent for the top dressing at effective tillering stage than that at primodial stage, for its slow effectiveness. 3. From the viewpoint of increasing paddy yield and nutrients uptake as well as the exchangeable potassium content of soil after harvesting, it seemed necessary to give a serious consideration to the development of such a compound fertilizer as used in this experiment which was prepared by the Chosen Fertilizer Industrial Cooporation on a trial base.

• Korean journal of applied entomology
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• v.41 no.2
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• pp.137-143
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• 2002

Grape phylloxera, Daktulosphaira vitifoliae(Fitch), is a destructive grape insect pest because it forms root galls and kills the plant by directly destroying root system. The effects of insecticide treatments were examined to establish the chemical control system of phylloxera, and the damage by this insect was investigated in grapevine yards. The treatments of 40kg carbofuran 3GR per ha and carbosulfan 20WP of 10$\ell$ (1,000$\times$) per tree successfully reduced phylloxera densities. After the insecticide treatments in early season, the phylloxera population rebuilt up again at harvest season. In a grapevine yard where two times of carbofuran treatment (mid-May and post-harvest treatment) were applied a year from 1998 to 2000, total yield per ha in 2000 showed an increase of 30% over that of 1998. But the yield in 2000 was low 20% compared to the average standard yield of Korean grapevine yards. In a grapevine yard without chemical treatment during the same years, total yield per ha in 2000 showed 53% reduction compared to that of 1998. Also, damaged vines by phylloxera abruptly increased from 3% in 1998 to 50% in 2000.

• Korean journal of applied entomology
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• v.11 no.1
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• pp.37-40
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• 1972

Experiments were carried out to control white-tip nematode, Aphelenchoides besseyi Christie, during the period just before transplanting. The experimental results were summarized as fellows: 1: From a 12-hr to a 24-hr sled-soaking application into 500 times dilutions of Malathion $80\%$ Ec, Sumithion $50\%$ EC and Lebaycid $50\%$ EC were highly effective than other emulsifierble concentrations of chemicals. 2) The water surface application of PSP-204 $5\%$ G, Diazinon $3\%$ G, Nemagon $20\%$ G and Terracurr-P $5\%$ G were effective. 3: Root·dipping application of Sumithion $50\%$ Ec, Lebaycid $50\%$ Ec and Nemagon $80\%$ Ec were more effective chemicals than others.

• Research in Plant Disease
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• v.7 no.1
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• pp.42-48
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• 2001

The effect of cultural, physical and chemical control methods on the population density of Meloidogyne arenaria second-stage juveniles (J2) and on fruit yields of oriental melon was investigated at Seongju Fruit Vegetable Experiments Station, Kyungpook province, Korea, for two years from 1999 to 2000. Crops used in a rotation prior to Oriental melon were rice, corn, sesame, and green onion. The physical methods used were either solarization, soil addition or soil drying, and a nematicide, fosthiazate of granular formula, was used as the chemical method, applying at a rate of 300g a. i./10 a. Growing rice in the rotation, solarization, and soil addition controlled the nematode disease most effectively, reducing the number of J2 by 90% and increasing fruit yields two times. However, the effects of these control methods on the J2 population were limited to the early growing season; the J2 population increased later, suggesting that additional control practices may be needed in the following season. The next effective control methods were use of corn in the rotation, the nematicide application, and soil drying. The nematicide application was effective only for the early fruit yield, but neither for the late nor for the total yields. Use of sesame or green onion in the rotation was not effective in controlling the nematode.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.6
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• pp.357-366
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• 2003

This study was conducted to develop n convenient and efficient granular type absorbent with high CEC from powdery zeolite, which is a waste produced while crushing the natural zeolite of Korea to get a particular particle size. The change of mineralogical characteristics during hydrothermal alternation of natural zeolite to Na-P zeolite in alkaline solution at various reaction times was determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and total elemental analysis. The columnar aggregate of Na-P Zeolite was produced by calcinating the natural zeolite-charcoal extrudates of about 3 mm diameter. In 24 hours reaction, clinoptillonite, mordenite and feldspar in natural zeolite were disappeared by 3 N NaOH treatment, while Na-P Zeolite with spherical granular structure was newly detected by XRD. As increasing reaction time, Si/Al ratio in remaining solution was deceased. The CEC of the synthesized material increased more than 2 times compared with that of natural zeolite, although the diameter of Na-P zeolite were rather increased.

• Journal of Biosystems Engineering
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• v.31 no.5 s.118
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• pp.389-394
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• 2006

The characteristic of moisture absorption of granular fertilizer was measured at several different opening sizes on the top cover of a hopper in a humid weather. The size of the opening was to represent the degree of looseness of sealing of the top cover of the hopper. The application distribution was characterized by the scattering distance of granular fertilizer with different degree of moisture absorption in a pneumatic granular fertilizer applicator. The moisture absorption rates were 12.92 and 12.26 mg of moisture an hour for one gram of each granular fertilizers of NPK 22-12-12 and 21-17-17, respectively. The moisture absorption increased linearly as the opening size increased. The median value of the scattering distance distribution decreased with time of absorption, however, it decreased very slowly after three hours of absorption.