• Journal of ILASS-Korea
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• v.14 no.2
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• pp.84-89
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• 2009

In this research, combustion and spray characteristics were investigated experimentally in a constant volume chamber by applying different composition rates of octane number in diesel fuel to a common-rail system. For the visualization, the experiment was carried out under different injection pressures and different cetane number. The test was done by three different types of diesel fuels, the different composition rates of cetane number in diesel fuel and HBD. In summary, this research aims to investigate the combustion characteristics in the application of fuels and compare the results with performance of conventional diesel fuel. This experimental data may provide with fundamentals of the development of diesel engines in future.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.200-203
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• 2008

Water mist fire suppression system utilizes the fire suppression features such as cooling of fire source, dilution of ambient oxygen, and shielding of radiation heat with the evaporation of microscopic water droplets. The momentum of water mist is relatively low and the infiltration of water mist to the fire source is not effective. In addition to lower penetration force, the evaporated water vapor is liable to decline to limited portion of fire source due to its light weight and sparse density. On the other hand, the cycling water mist system is expected to improve the penetration force of water mist as well as the dilution coverage capability with the stratified spray characteristics. At this paper we present the analyzed fire suppression capability of intermittent water spray pattern by use of FDS which is computational fire dynamics fire model. We expect this analysis shall be supportive to the development of the prototype of water mist nozzle.

• Journal of Biosystems Engineering
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• v.25 no.4
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• pp.287-292
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• 2000

The herbicide penetration on weed leaves was spatially analyzed by using chlorophyll fluorescent emission and machine vision technique. Velvetleaf and metribuzin were used as experimental materials in the study. The herbicide spray images were obtained by a combinaton of a fluorescent dye and a UV lighting system. The herbicide penetration was analyzed by means of detecting chlorophyll fluorescent emission under blue-green lighting. According to the experiment results, the number and the size of spray droplets decreased with coverage increasing. The herbicide penetrated mainly along leaf veins and the time for complete penetration over the whole leaf was approximately 100 minutes after herbicide spraying. When the coverage of herbicide droplets on the surface of leaves increased, the speed of herbicide penetration also increased. This study suggested a way of characerizing herbicide spatial penetration and distribution in leaves.

• Journal of Drive and Control
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• v.17 no.4
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• pp.1-7
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• 2020

In orchard or crop-growing environments, pesticides are sprayed using various nozzles to prevent pests and improve productivity. Nozzles currently in use are restricted for use in multi-purpose environments, thus, it is necessary to develop new nozzles. In this study, new two-phase nozzles are proposed to improve the performance of the nozzle (flow rate, spray angle, spray particle size). The performance of the two-phase nozzles are predicted through the CFD analysis and the performance of the nozzles is compared with the experiment. The experimental results showed that the proposed two-phase nozzles are available at relatively low operating pressure condition and are capable of extensive spray particle size control. Thus, the proposed nozzles are expected to be available in various orchard environments.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.103-111
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• 2006

The spray behavior of direct-injection spark-ignition(DISI) engines is crucial for obtaining the required mixture distribution for optimal engine combustion. The spray characteristics of DISI engines are affected by many factors such as piston bowl shape, air flow, ambient temperature, injection pressure and fuel temperature. In this study, the effect of fuel temperature on the spray and combustion characteristics was partially investigated for the wall-guided system. The effect of fuel temperature on the fan spray characteristics was investigated in a steady flow rig embodied in a wind tunnel. The shadowgraphy and direct imaging methods were employed to visualize the spray development at different fuel temperatures. The microscopic characteristics of spray were investigated by the particle size measurements using a phase Doppler anemometry(PDA). The effect of injector temperature on the engine combustion characteristics during cold start and warming-up operating conditions was also investigated. Optical single cylinder DISI engine was used for the test, and the successive flame images captured by high speed camera, engine-out emissions and performance data have been analyzed. This could give the way of forming the stable mixture near the spark plug to achieve the stable combustion of DISI engine.

• Horticultural Science & Technology
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• v.30 no.1
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• pp.90-92
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• 2012

A new spray carnation 'Lepus' was released by the National Institute of Horticultural & Herbal Science in 2004. This hybrid was crossed between 'Diamond' and '99257-7 Line' in 2000. The 269 seedling plants were, planted and cultivated in green house. After investigation of the characteristics for four years (from 2001 to 2004), it was finally selected in 2004. 'Lepus' white color with red peak edge is spray type and strong flower stalks. Also, it has medium fragrance, many flowers, and attractive flower arrangement. In particular, flowering was 10 days early and flower stalk was 13cm longer than 'Diamond' (control). In addition, it has medium resistance of Fusarium and the vase life was similar to 'Diamond'.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.166-173
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• 2007

In a trial to select suitable fungicides for developing a spray program that can control apple white rot effectively, after-infection activities in some protective fungicides were detected. Six fungicides, mancozeb, propineb, benomyl, folpet, azoxystrobin and iminoctadine-triacetate, which had been extensively used in apple orchards, were sprayed on 12-year-old apple trees (cv. Fuji) at 15-day intervals from late May to late July. Disease incidences and infection frequencies of the fruit bagged just before and soon after each spray were examined. When the infection frequency or disease incidence of the fruit bagged after each spraying of fungicide was significantly lower than those of the fruit bagged before spraying, the fungicides appeared to confer after-infection activity. The six fungicides showed diverse activities on white rot: folpet showed after-infection activity on disease development, iminoctadine-triacetate showed after-infection activity on infection, azoxystrobin showed after-infection activity on disease development and infection, and mancozeb, propineb and benomyl showed no distinct activity. The activity of a fungicide became much higher when it was sprayed alternately with other fungicide rather than successive spraying of the same fungicide. Analysis of the properties of these protective fungicides could lead to the development of a highly effective spray program against white rot.

• Korean Journal Plant Pathology
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• v.11 no.1
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• pp.17-29
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• 1995

This study was conducted from 1991 to 1993 to develop a fungicidal spray program for the apples exportable to the United States of America, in which quarantine and pesticide residue in agricultural products are strictly regulated. In 1991, 2 spray schedules were applied to an orchard, in one of which the 7 fungicides registered for apple both in Korea and U.S. were used, and in the other of which the Bordeaux mixture for which the tolerance was exempted in U.S. was used 2 times along with those 7 fungicides. The apple white rot and fruit infection by Alternaria mali were not effectively controlled by the 7 fungicides alone; however, the control efficacy was raised by adding the Bordeaux mixture to the spray schedule. In 1992, 4 spray schedules were applied in which the kinds of fungicides and spray intervals were different one another. The results suggested that an effective spray program can be developed by adopting the Bordeaux mixture for 3 times or adopting the imminoctadine-triacetate which has not tolerance level in U.S. for same times in the vulnerable stage of apple white rot and alternaria blotch. In spite of the high efficacies against major apple diseases, the Bordeaux mixture could not be recommended to the apple growers due to the various defects such as restrictions in compatibility with insecticides and acaricides, troublesomeness in preparation and spray, especially the harmful effect on the finish of Fuji apples. In 1993, a spray program adopting 3 times of imminoctadine-triacetate during the growing season of apple was developed, which not only can effectively control the major apple diseases but also avoid the pesticide residue problems if it was sprayed 2 or 3 times after bagging. On the basis of the 3 years results, a basic fungicide spray program was formulated in which 1~3 times of imminoctadine-triacetate and 1~2 times of bitertanol were adopted in addition of the 7 common fungicides registered in both countries. In the results of application of the spray schedule to the actual farming in the 4 areas of Kyungpook Province in 1994, no noticeable defects were detected at the first year trial. However, this spray program will be continuously evaluated and modified to obtain better control efficacies against major apple diseases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.270-275
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• 2016

The characteristics of the fuel quantity, injection rate and macro spray development was investigated under a range of diesel fuel temperatures. The actual injection quantity decreased despite the same signal of the injection start and injection duration as the fuel temperature decreased. The injection rate measurements confirmed that the actual injection commencement was delayed and the actual injection duration was shortened under lower fuel temperature conditions, which explains why the injection quantity decreased. Spray tip penetration with a lower fuel temperature was longer than that with a higher fuel temperature due to the deteriorated atomization. As a pre-test for the combustion experiment under low temperature conditions, piston targeting with pilot injection was accomplished, which showed that the fuel droplet from pilot injection was introduced into the crevice area. This suggests that the pilot injection quantity and timing should be chosen with careful consideration for actual applications.

• Journal of Biosystems Engineering
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• v.35 no.4
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• pp.215-223
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• 2010

In order to develop an precision aerial pesticide application system to be attached to an unmanned helicopter which can be applied to small lots of land, this study analyzed the flowing and spraying characteristics of the spray droplets by the main rotor downwash by setting the application conditions at the flight altitude of 3 m, the diameter of main rotor of 3.1 m, the boom length of around 2.8 m, and the spraying rate of 8 L/ha. The results of this study are summarized below. Through analysis of the covering area ratio of the spray droplets by main rotor downwash by nozzle type, boom with tilt angle and height, it was found that the covering area ratio of the twin flat-fan nozzle of around 25% was more uniform than other types of nozzle, also boom with $10^{\circ}$ tilt angle and spraying height of 3 m was shown to be the appropriate conditions for aerial application of pesticides. It was found that the nozzle position to minimize the scattering loss of spray droplets due to vortex phenomenon at both ends of the main rotor was around 10 cm from the end of the main rotor. An application test for the aerial pesticide application system attached to the HUA-ACEI unmanned helicopter developed by the Rural Development Administration showed that the range of covering area ratio of the spray droplets was 10-25%, and the spraying width was approximately 7 m when over 10% of covering area ratio was considered for valid spraying.