• Journal of Bio-Environment Control
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• v.32 no.2
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• pp.106-114
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• 2023

With rising concerns about pesticide spray drift by aerial application, this study attempt to evaluate aerodynamic property and collection efficiency of spray drift according to the leaf area index (LAI) of crop for preventing undesirable pesticide contamination by the spray-drift tunnel experiment. The collection efficiency of the plant with 'Low' LAI was measured at 16.13% at a wind speed of 1 m·s^-1. As the wind speed increased to 2 m·s^-1, the collection efficiency of plant with the same LAI level increased 1.80 times higher to 29.06%. For the 'Medium' level LAI, the collection efficiency was 24.42% and 43.06% at wind speed of 1 m·s^-1 and 2 m·s^-1, respectively. For the 'High' level LAI, it also increased 1.24 times higher as the wind speed increased. The measured results indicated that the collection of spray droplets by leaves were increased with LAI and wind speed. This also implied that dense leaves would have more advantages for preventing the drift of airborne spray droplets. Aerodynamic properties also tended to increase as the LAI increased, and the regression analysis of quadric equation and power law equation showed high explanatory of 0.96-0.99.

• Journal of Biosystems Engineering
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• v.20 no.4
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• pp.313-322
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• 1995

This study was conducted to find the design factors of spraying device of the boom sprayer for low volume application. Specific objectives of this study were 1) to select proper nozzles for broadcast spraying and row crop spraying by the nozzle spray characterisic experiment, and 2) to investigate the coverage characteristic of rice plant at the row crop spraying. The results of this study are summarized as follows. (1) From the tested results on the droplet diameter spectrum and spray pattern the standard flat-fan nozzle and drift guard nozzle were judged as appropriate for the broadcasting. Even flat-fan nozzle showed similar span values to standard flat-fan nozzles and drift guard nozzle : however, the nozzles were found to be inappropriate for broadcasting because of their spray pattern. Hollow cone nozzle showed relatively small span values and uniform spray pattern. (2) For the upper and lower sides of the rice plants, coverage rates of even flat-fan nozzles and hollow cone nozzles were maximum at the second row, but decreased rapidly after the third row. For the middle side of the rice plants, coverage rates of them were maximum at the first row, but decreased rapidly. When one nozzle was tested, C.V. values were in the range of 90~160% and 60~160% on entire heights of rice plant for even flat-fan nozzles and hollow cone nozzles respectively. C.V. values at other parts were poor. Spray coverage rate at the middle part was improved by overlapping the nozzles whereas there was little difference on the upper and lower part of rice plants. (3) For spraying lower part of rice plant between rows, even flat-fan nozzles and hollow cone nozzle were judged as appropriate, but in order to ensure the uniform coverage, distance between nozzles, recommended to be less than 90cm.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2009.10a
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• pp.77-80
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• 2009

• Korean Journal of Weed Science
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• v.7 no.3
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• pp.337-347
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• 1987

Spary and vapor drift injuries of apple, pear, and peach seedling caused by soil-applied oxyfluorfen were studied in a greenhouse. Bud bursting rate of all fruit trees was reduced by both spray and vapor drifts of oxyfluorfen, but reduction in bud bursting rate of pear and peach was greater than that of apple trees. Reduction in the number of leaves per shoot of apple and peach was greater than that of pear trees. Leaf injury of pear was most severe and occurred earliest, but leaves of peach were least injured, Leaf injuries of pear and apple were caused by both spray and vapor drifts, but leaves of peach was injured largely by vapor drift. Reduction in shoot growth of and pear was greater than that of peach trees. Shoot growth of pear was more rapidly retared compared with apple trees. In the field, oxyfluorfen delayed the time of bud bursting in young apple trees. Oxyfluorfen applied between initiation and completion of bud bursting delayed bud bursting more than earlier application although ultimate number of bursted buds was similar to control. The number of leaves per shoot and total length of shoots were lower than control until 40 days after application of oxyfluorfen, and then were similar to control because of vigorous growth after May.

• Korean Journal of Environment and Ecology
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• v.24 no.1
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• pp.14-25
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• 2010

This study was carried out to investigate the soil salinity and salt spray drift of the indigenous windbreak trees, and its main purpose was to provide basic data for the selection of salt-tolerant trees in the saline coastal region in the South Sea of Korea. The soil salinity($EC_{1:5}$)was $0.18dSm^{-1}$, which was an average degree of the whole areas of investigation whose salinity degree ranged from $0.05dSm^{-1}$ to $0.58dSm^{-1}$. The level of soil salinity gradually decreased as it moved farther inland, except the belt I. The level of decreasing soil salinity was found to be in the following order: belt II, belt III, belt I, belt IV. The degree of soil salinity was $EC_{1:5}$ $0.22dSm_{1:5}$, $0.22dSm_{1:5}$ $0.19dSm^{-1}$ and $0.13dSm^{-1}$ respectively. The total 110 taxa, which consisted of 45 families, 74 genus, 101 species, and 9 varieties, were found to be tolerant to both soil salinity and salt spray drift. The trees that grow in the highest degree of salinity($EC_{1:5}$ $0.50dSm^{-1}$)were Parthenocissus tricuspidata(Siebold & Zucc.), Planch and Lonicera japonica Thunb. The next group of trees that grow in the high degree of salinity ranging from $EC_{1:5}$ 0.41 to $0.50dSm^{-1}$ was Cudrania tricuspidata(Carr.) Bureau ex Lavall$\acute{e}$e, Rubus parvifolius L., Zanthoxylum schinifolium(Siebold & Zucc.), Hedera rhombea(Miq.) Bean., Robinia pseudoacacia L., Quercus serrata Thunb., Callicarpa dichotoma(Lour.) K. Koch, and so on. The woody species which grew in the entire belts were Pueraria lobata(Willd.) Ohwi and Vitis flexuosa Thunb., and Vitex rotundifolia L. f. which was known to be highly tolerant to salt spray drift was found only in belt I. The woody species with high important value(IV) were Zelkova serrata(Thunb.) Makino., Celtis sinensis Pers., Koelreuteria paniculata Laxmann, Mallotusjaponicus(Thunb.) Muell. Arg., Trachelospermum asiaticum(Siebold & Zucc.) NAKAI, and Pueraria lobata(Willd.) Ohwi. These species were classified as native windbreak trees that are comparatively more tolerant to salt spray drift than other kinds.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1998.10a
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• pp.1-4
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• 1998

상온연무기와 같은 소량살포기에 의해 살포된 농약액의 입자경은 10-20$\mu\textrm{m}$ 이하의 것이 대부분이다. 미소 액적은 단시간에 공기의 습구 온도와 평형하게 되어 혼합, 확산되는 특성을 가지고 있으며 증발과 Drift현상이 발생된다. 시설원예의 경우 폐쇄환경에 있으므로 연무직후 온실내 작업의 제한, 부착력포의 불균일, 증발과 Drift량의 과다 등이 큰 문제가 된다. (중략)

• Agricultural and Biosystems Engineering
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• v.3 no.1
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• pp.29-34
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• 2002

Two charging methods of electrostatic nozzle, i.e. induction and ionized field corona charging, were designed and evaluated for orchard sprayer application. An artificial (metallic) target was constructed and used in this experiment. The charge-to-mass ratio for the induction electrode was measured by using the Faraday cage. Two conventional pressure-swirl nozzles have been employed with different orifice diameters under the same experimental operating conditions. A commercial pressure-swirl nozzle with orifice diameter of 1.0 was used for the conventional spray. The diameter of the electrostatic was 0.59 mm. The experiment was carried out for individual nozzle sprays at $0^{\circ}$, $20^{\circ}$ and $50^{\circ}$ oriented angles and three nozzles, sprayed simultaneously at a distance of 1.0 and 2.0 m from the nozzle tip to the target. The nozzles were mounted on a carriage with constant speed of 1.26 km/h with a blower attached. The weighing method was employed to evaluate for the spray deposition, ground loss and estimated drift. The results show more promising for the induction charging method, especially at $20^{\circ}$oriented angle at a distance of 1.0 m from the target for a single nozzle and when all three nozzles were operated simultaneously for spray deposition. The results of the induction charging method show promising with the developed electrostatic technique.

• Korean Journal of Environment and Ecology
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• v.24 no.2
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• pp.209-221
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• 2010

This study was carried out to apply basic data of the native trees for planting in the salinity area by the vegetation ecological selection. Which focused on native woody species to the tolerances of saline soil and salt spray drift on the coastal forests in the West-Sea, Korea. The soil salinity($EC_{1:5}$) was 0.11dS$m^{-1}$, ranging of 0.00dS$m^{-1}$~0.68dS$m^{-1}$. The soil salinity was gradually decreasing from Belt I to Belt Ⅳ except the Belt I in some coastal windbreaks. The order of decreasing soil salinity was Belt I>Belt II>Belt III>Belt Ⅳ and the soil salinity was $EC_{1:5}$ 0.14dS$m^{-1}$, 0.11dS$m^{-1}$, 0.10dS$m^{-1}$, and 0.08dS$m^{-1}$, respectively. The total 181 taxa consisted of 52 families, 104 genus, 157 species, and 24 varieties were recorded as the trees tolerating to both soil salinity and salt spray drift. The trees emerged in the highest degree of salinity($EC_{1:5}$ 0.51dS$m^{-1}$) was nothing but appearanced Pinus thunbergii Parl., Smilax china L., Quercus dentata Thunb. ex Murray, Quercus serrata Thunb. ex Murray and so on at the level of singular and ideal value. The emerged trees in the high salinity of $EC_{1:5}$0.41dS$m^{-1}$~0.50dS$m^{-1}$ were Albizia kalkora Prain, Melia azedarach L., Paederia scandens (Lour.) Merr. var. scandens These species were trees of tolerance to saline soil. The emerged woody species in all belts were Pinus rigida Mill., Pinus densiflora Siebold & Zucc., Pinus thunbergii Parl., Juniperus rigida Siebold & Zucc. and so on. The woody species with high important value(I.V.) were Pinus densiflora Siebold & Zucc., Pinus thunbergii Parl., Pseudosasa japonica (Siebold & Zucc. ex Steud.) Makino, Smilax china L., Platycarya strobilacea Siebold & Zucc. var. strobilacea for. strobilacea and so on, which can be classified as highly tolerant native trees to salt spray drift.

• Journal of Biosystems Engineering
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• v.26 no.5
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• pp.431-440
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• 2001

Generated agri-chemical droplets by orchard sprayers are evaporated regenerated and transported along wind streams. The droplets are deposited to targets after changing their sizes, affecting the retention of droplets. An orchard sprayer, designed for spraying grapevines was studied on the spatial distribution of droplet size. The experimental variables were spray direction (0, 22.5, 45, 67.5 and 90˚), distance(2.5, 3.0 and 3.5 m) and fan speed (2,075 and 3,031 rpm). Droplet sizes were converted and analyzed from spray stains, sampled using water sensitive papers. The number median diameter (NMD) increased with an increase of the distance due to disappeared fine droplets (<50 ㎛): however, the volume median diameter (VMD) decreased due to shrunken large droplets (>100 ㎛). Fast fan speed delivered large droplets to 3.5 m, but the spatial distributions of NMD and VMD were not uniform. Slower fan speed decreased the possibility of evaporation and drift; therefore, plenty of droplets were maintained up to 3.0 m. The upward blasting distance was limited within 3 m, but the limit to the ground level was extended to 3.5 m. Concentrated wind and droplets to the ground level should be redistributed to upper canopy direction, leading more uniform deposits. High speed wind and system pressure should be avoided because of generating fine droplets, which would be disappeared and drifted away.

• Journal of Biosystems Engineering
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• v.41 no.4
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• pp.337-341
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• 2016

Purpose: Evaluation of atmospheric conditions for proper timing of spray application is important to prevent off-target movement of crop protection materials. Susceptible crops can be damaged downwind if proper application procedure is not followed. In our previous study, hourly data indicated unfavorable conditions, primarily between evening 18:00 hrs in the evening and 6:00 hrs next morning, during clear conditions in the hot summer months in the Mississippi delta. With the requirement of timely farm operations, sub-hourly data are required to provide better guidelines for pilots, as conditions of atmospheric stability can change rapidly. Although hourly data can be interpolated to some degree, finer resolution for data acquisition of the order of 15 min would provide pilots with more accurate recommendations to match the data recording frequency of local weather stations. Methods: In the present study, temperature and wind speed data obtained at a meteorological tower were re-sampled to calculate the atmospheric stability ratio for sub-hour and hourly recommendations. High-precision evaluation of temperature inversion periods influencing atmospheric stability was made considering strength, time of occurrence, and duration of temperature inversion. Results and Discussion: The results indicated that atmospheric stability could be determined at different time intervals providing consistent recommendations to aerial applicators, thereby avoiding temperature inversion with minimal off-target drift of the sprayed liquid.