• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.2
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• pp.2980-3001
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• 1973

Nozzle is a part of sprayer and is consists of several elements; swirl plate, vortexchamber, cap and body. The travelling distance of sprayed particles is important in the wide reach nozzle. The factors to influence the travelling distance of the sprayed particles may be the helical angle of swirl plate, the distance of vortex hamber, the slope and the size of cap hole. The study was conducted to examine the effects of these factors on the travelling distance. The results of this study are summarized as follows; 1) There was higher positive correlation(+0.96) between the maximum travelling distance for which amount of sprayed particles was 5cc/cm min. and centro-position of the travelling distance. 2) There was a higher positive correlation(+0.85) between total discharge of sprayed particles and the centro-position of the travelling distance. 3) Main effects and interaction effects of helical angle, pressure, vortex chamber distance and cap slope were significantly affected the travelling distance of sprayed particles. 4) Main effects of helical angle, pressure and cap slope were especially highly significant to influence the travelling disance. 5) Helical angle, pressure, vortex chamber distance and cap slope influenced spraying forward velocity of dise hole, among which cap slope and pressure of nozzle was the most important factors. 6) Effect of change of helical angle on the travelling distance of sprayed particles, was generally a quadratic, the least value of the distance being showed about $45^{\circ}$ and the largest at about $15^{\circ}\;and\;55^{\circ}$, the decreasing rate of the change between $15^{\circ};and\;25^{\circ}$ was very small. 7) Effect of change of pressure on the travelling distance sprayed particles was generally a linear, the increasing rate of the charge was about 1.68, which was the most effective compared to the change of the other factors. 8) Effect of change of vortex chamber distance on the spraying distance was also generally a linear, the increasing rate being about 0.16, which was the least effective. 9) Effect of change of cap slope on the travelling distance was also generally a linear, the increasing rate was about 0.61 and its effect was about medium.

• Journal of Korean Society of Forest Science
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• v.94 no.1 s.158
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• pp.21-25
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• 2005

In order to prevent the pine mushrooms, Tricholoma matsutake, from being damaged by the pine needle gall midges, Thecodiplosis japonensis, and thereby, to increase their production and improve their quality, a sprinkler system was installed on the mushroom field. A low-concentration insecticide (deltamethrin 1% EC, x2,000) was sprayed once at insects' most active time every day during the period of insects' adult occurrence and thereafter, the irrigation by ground water spraying was periodically enforced. Such a test was conducted at Yangyang-Gun, Kwangwon-do, Korea for 2 years from 2000 through 2001. The pine needle gall midges generally emerged for about 40 days from late May to early July. 50% emergence of them was about June 6, and peak emergence (more than 80%) was early or mid-June. Gall formation rate was 3.5% on average with this ground insecticide spraying, while 51.3% when not treated. Control effectiveness of this insecticide spraying was 92.3%, which was higher than 82.5% by the conventional injection of insecticide into tree stems. Pine mushrooms emerged for about 35 days from mid-September through earlier October, and around 80% of them did for about 15 days from late September through early October. As a result of the periodic ground water-spraying (30 mm per week) for 2 months (from August to October), the production of mushrooms increased by 74.3% (110% in terms of weight), with their quality improvement. The mushrooms produced from the treated stand by the spraying system were priced 8,670,000 wons per hectare, and thus, the net income deducting the facility and management cost was 4,310,000 wons, about 5% higher than value from the control stand. It was analyzed that this treatment was significantly cost effective when the facilities are used more than 5 years.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.153-163
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• 2010

This study was carried out to establish an improved bioassay system, whole-plant bioassay which is more effective in developing natural herbicides for foliar treatment such as herbicidal essential oils. Two bioassay systems using four weed species (Echinochloa crus-galli, Digitaria sanguinalis, Aeschynomene indica, and Abutilon theophrasti), spraying method and spotting method, were established. Spraying method is applicable if the amount of test compounds is enough, while spotting method is useful for the small amount of test compounds. The initial application rate was desirable at $2,500{\sim}5,000\;{\mu}g\;mL^{-1}$. Herbicidal activities were higher in the NOP treatment when compared to the Tween 20 treatment. To efficiently evaluate volatile compounds such as essential oils, if the compound-treated pots were incubated in dew chamber for about 10hrs, better results were obtained in the degree and stability of herbicidal responses. When the efficiency of bioassay systems established in this study was compared, the spraying method was minimized four times to the conventional method that has beed used for screening of synthetic compounds in KRICT. On the other hand, in the spotting method, screening for development of a natural herbicides was possible even in level of 1/100 test volume and 1/200 amounts of test compound compared to the spraying method.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.487-494
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• 1993

In order to establish a fully automatized pest control in the a greenhouse , the authors developed a prototype of microcomputer installed spraying vehicle which traveled along the furrows. Since a power sprayer mounted on the vehicle was driven by gasoline engine, plants grown in the greenhouse might be injured by the gas exhausted from the engine. Thus , effects of exhausted gas on photosynthetic rate and the shedding of flowers and buds of plants were examined. At first, effects of exhausted gas on photosynthetic rate of potted sweet pepper (Capsicum annuum L.) and eggplant(Solanum melongena L.) plants were examined. In a closed vinyl house the engine was operated for 5 minutes and plants were exposed to the gas for 2hours in the daytime on a fine day. Photosynthetic rate did not significantly decreased by the treatment in both species. Secondly, effects of ehtylene on the shedding of flowers and buds of sesame (Sesamum indicum L. ) were examined. In the closed and partiall opened vinyl house, the engine was operated for 5 minutes and potted sesame plants were exposed to the gas for 12 hours in the night. In partially opened vinyl house, ethylene concentration decreased to 0 ppm 3 hours after the engine was stopped and flower and bud did not shed. In contrast, when vinyl house was closed ethylene concentration was 0.75 pm even 12 hours after the engine was stopped and flowers and buds shed markedly and epinasty was observed in upper young leaves. As mentioned above , it was revealed that injury of plants in the greenhouse caused by the gas exhausted from a gasoline engine could be prevented by providing suitable ventilation.

• Journal of agricultural medicine and community health
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• v.25 no.2
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• pp.245-263
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• 2000

This study was conducted to provide the basic data about the health effects of pesticide exposure among farmers for agricultural health study. We analyzed 412 self-administered questionnaires collected from the male farmers who spray pesticides in Kyoung-ju area, Korea. Survey questions were about chronic symptoms, acute symptoms while pesticide spraying, pesticide intoxication accident, safety rules, protective equipments etc. The correlations among the variables related to pesticide exposure and the factors in acute pesticide poisoning and chronic symptoms of farmers were also analyzed. For chronic symptoms, the prevalence of 'tiredness and languor', 'lumbago', 'nocturia', 'shoulder pain', 'numbness', and, for acute symptoms while pesticide spraying, the experience rate of 'itching sense of skin', 'dizziness/headache', 'fatigue', 'eye glaring' were high compared with other symptoms. For 'experience of intoxication accident by pesticide in family', 7.1% of the subjects experienced the accident and the causes were pesticide spraying, food contamination by pesticide, suicide etc. Among safety rules, 'take a bath after spraying', 'change clothes after spraying' were kept relatively well, and, for protective equipments, hat, boots, mask, gloves, protective clothes(lower) were put on relatively well. The factors associated with acute pesticide poisoning were the extent of keeping safety rules, spraying time, orchard cultivation, agricultural area and spraying days per year etc. And the factors associated with chronic symptoms were acute symptoms while pesticide spraying, agricultural area, farming career, extent of keeping safety rules, extent of agricultural work and the pesticide exposure index etc. From these results, it is suggested that to reduce the health effects by pesticide exposure among farmers, the education to promote to keep safety rules and wear protective equipments, and information services should be recommended. And further studies on the long term health effects of pesticide exposure among farmers are required.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.12
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• pp.1292-1297
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• 2005

The use of ozone in water and wastewater treatment systems has been known to be a process that is limited by mass transfer. The most effective way to overcome this limitation is to increase the interfacial area available for mass transfer by decreasing the size of the ozone gas bubbles that are dispersed in solution. Electrostatic spraying(ES) of ozone into water was investigated in this work as a method of increasing the rate of mass transfer of ozone into a solution and thereby increasing the rate of phenol oxidation. Results were obtained for ES at input power levels ranging from 0 to 4 kV and compared with two different pore-size bubble diffusers($10{\sim}15{\mu}m$ and $40{\sim}60{\mu}m$). It was determined that the rate of mass transfer could be increased by as much as 40% when the applied voltage was increased from 0 to 4 kV as a result of the smaller bubbles generated by ES. In addition, ES was shown to be more effective than the medium-pore-size($10{\sim}15{\mu}m$) bubble diffuser and the best results were achieved at low gas flow rates.

• The Plant Pathology Journal
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• v.25 no.2
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• pp.151-156
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• 2009

Tomato spotted wilt virus (TSWV) has occurred on fields annually disease occurrence rates were 73.3% in 2005, 53.3% in 2006 and 41.6% in 2007 at Anyang area in Gyeonggi Province. Seasonal occurrence pattern of TSWV showed a dramatic increase from 8.7% in late May to 30.1 % in early June in 2007 at Anyang area, coincided with the high population of a thrip, Frank-liniella occidentalis at that time. The rate of viruliferous thrips with TSWV on lettuce and red pepper was 20.2% and 52.1%, respectively, in greenhouses. Dazomat, soil fumigation pesticide, reduced TSWV disease incidence drastically on table tomato as treatment the chemical into the soil with humidity in early spring in 2006 and 2007. Spraying insecticide periodically after treatment with Dazomat was more effective to control TSWV than spraying if on plants or applying into the soil of the insecticide during growing season. Control efficiency through treatments both of the soil fumigation and of spraying insecticide was significantly high with 85.3% in 2006 and 87.8% in 2007. Removing the potential vector from the soil of TSWV infested area can be an effective strategy for reducing TSWV disease.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.258-264
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• 2017

Purpose: This study determines the spray characteristics and effective spray width of a tractor-mounted commercial boom sprayer through experiments. Methods: Performance tests were conducted to investigate the spray characteristics of the nozzles on a commercial boom sprayer. The flow rate and spray width of a single nozzle were measured at three levels of spray pressure (0.5, 0.7, and 1.0 MPa) and spray height (15, 30, and 45 cm), respectively. The average value of three repetition tests was used as the representative value. A coefficient of variation (CV) was used as an index of spray uniformity, and the width that guarantees CV values of approximately 15% was determined as the effective spray width. The spray characteristics of the overall boom sprayer were derived analytically by superimposing the spray characteristics of a single nozzle. Results: The test results for a single nozzle showed that the spray width tended to increase as the spray height and spray pressure increased. The effective spray width for a single nozzle was the largest at a spray pressure of 1.0 MPa and spray height of 45 cm, which resulted in a coverage of 84 cm of width. The effective spray width for the entire boom sprayer was also the largest at the spray pressure of 1.0 MPa and spray height of 45 cm, with a magnitude of 424.5 cm. The chemical spraying work in an actual field was simulated by applying a spray width of 400 cm. As a result of the operation for three swaths, the CV value was less than 10% for 1,200 cm of the overall spray width, which meant that uniform application was achieved. Conclusions: It was reasonable to set the effective spray width of the boom sprayer used in this study to 400 cm.

• The Korean Journal of Pesticide Science
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• v.12 no.2
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• pp.118-126
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• 2008

In order to find the best compositions of the dimethomorph formulation containing fatty alcohol ethoxylate surfactants as an activator adjuvant and recommend the good management way of the formulations to allow an intended uptake rate, factors affecting foliar uptake of active ingredients into cucumber were investigated and compared each other. Among tested, the most important factors were air temperature in which plants were located after spraying of aqueous formulations containing activator adjuvant, and deposit of wax on the leaf surface of cucumber. Dimethomorph uptake was found to be increased by sunlight. When aqueous formulations had long-polyethoxylated fatty alcohol surfactants, the relative humidity of the room in which the plants were located after spraying with the formulations did not severely influence the foliar uptake. Maintaining a mild temperature and avoiding too strong sunlight after spraying with dimethomorph formulations were found to be resonable management strategies.

• Journal of Ocean Engineering and Technology
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• v.35 no.1
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• pp.24-37
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• 2021

As one of the development directions of high-performance ships to reduce greenhouse gas emissions, there is research on high-performance propellers. However, in the case of conventional screw propellers, as they have been studied for a long time, there is a limit to improving efficiency only by depending on the conventional design and analysis methods. In this study, we tried to solve the problems using the Coanda effect by spraying a jet on the surface of the hydrofoil. The Coanda hydrofoil consists of a tunnel and jet slit to make jet flow. The computation was performed for each tunnel and slit position, and the efficiency according to the geometry of the hydrofoil was analyzed. In addition, a study on the 3D geometry change was conducted to analyze the performance according to the span direction spraying range and hydrofoil shape. As the height of the slit and the diameter of the tip were lower, when the slit is located in the center of the hydrofoil, the lift force increased and the drag force decreased. The increase rate of lift-to-drag ratio was different according to the shape of the hydrofoil, and the efficiency of the spraying condition of 0.1S-0.5S, which had the least effect on the vortex at the tip of the blade, was high for all 3D hydrofoils. When the geometry of the slit was optimized, and also the shape and spray range of the hydrofoil in 3D was considered, the efficiency of the jet sprayed hydrofoil was increased.