• Korean journal of applied entomology
• /
• v.59 no.2
• /
• pp.83-91
• /
• 2020

We assessed efficacy of spraying pesticides from an unmanned helicopter to control two insect species, Monochamus alternatus and M. saltuarius, which are vectors of pine wood nematodes. Control efficacy of thiacloprid FL (33×), acetamiprid ME (33×), and flupyradifurone SL (33×) was determined by placing caged insects in the canopy of pine trees (Pinus sp). Water-sensitive paper was used to record the spray pattern of pesticide droplets and the degree of coverage; furthermore, we investigated peripheral scattering due to spraying. The three pesticides showed > 96% control efficacy against the targeted vectors, and pesticide droplet spray patterns were similar. Peripheral scattering was observed up to 20 m in front and 10 m to the left, right, and behind the targeted area. The coverage index of all the directions at 5 and 10 m distance was 6-7 and 2, respectively.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.6 no.2
• /
• pp.37-44
• /
• 2002

A theoretical study of spray and combustion characteristics due to coaxial twin-fluid injection is conducted to investigate the effects of liquid jet property, droplet size, contact length and liquid jet velocity. Model is properly validated with measurements and shows good agreement. Prediction of jet contact length, droplet size, liquid jet velocity reflects genuine features of coaxial injection in physical and practical aspects. Both the jet contact length and tile droplet size are reduced in a linear manner with an increase of injector diameter. Cross sectional area of liquid intact core is reduced with augmented jet splitting rate, thus the jet is accelerated to maintain the mass continuity and with an assistant of momentum diffusion by burnt gas.

• Research in Plant Disease
• /
• v.18 no.1
• /
• pp.40-44
• /
• 2012

Xanthomonas arboricola pv. pruni is the causal agent of bacterial black spot disease on some stone fruits, e.g. peach, plum and apricot. To evaluate pathogenicity of Xanthomonas arboricola pv. pruni strain from plum, inoculum of the isolated strain was spray inoculated to fruits and leaves of apricot, Japanese apricot and plum. Apricot and Japanese apricot showed severe black spot symptoms on fruits and shot hole symptoms on leaves. In case of apricot, about fifty percent of fruits did not grow and dropped by hypersensitive reaction to spray infection. Plum, cv. Formosa was very susceptible, showing severe black injury lesions on fruits and cankers on leaves and new twigs. On the other hand, plum cv. Daesukjosaeng, was highly resistant. Fruits of several plum cultivars such as Formosa and Chuhee were severely infected at natural infected orchards by X. arboricola pv. pruni. Where as those of Daesukjosaeng, Taeyang, Soldam and Hongrogen were moderately infected.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.5
• /
• pp.73-79
• /
• 2021

This study was carried out to analyze the properties of the gel propellant and spray characteristics according to the addition of fine particles. The multi-hole diameter was 0.4 mm to induce a high shear rate, and a kerosene gel propellant was prepared using 5 wt% of the Thixatrol ST and SUS304 of 100 nm. The experiment was conducted by fixing the supply pressure in the axial direction to 0.7 MPa and adjusting the supply pressure in the radial direction from 0.7 MPa to 2.1 MPa. Due to the addition of fine particles, pressure vibration during spraying, a small TMR(Total Momentum Ratio) of up to 0.19, and a phenomenon that the spraying angle rapidly increased to more than 70 degrees occurred.

• Applied Chemistry for Engineering
• /
• v.26 no.3
• /
• pp.319-325
• /
• 2015

Submicron-sized $CeO_2:Er^{3+}/Yb^{3+}$ upconversion phosphor particles were synthesized by spray pyrolysis, and their luminescent properties were characterized by changing the concentration of $Er^{3+}$ and $Yb^{3+}$. $CeO_2:Er^{3+}/Yb^{3+}$ showed an intense green and red emission due to the $^4S_{3/2}$ or $^2H_{11/2}{\rightarrow}^4I_{15/2}$ and $^4F_{9/2}{\rightarrow}^4I_{15/2}$ transition of $Er^{3+}$ ions, respectively. In terms of the emission intensity, the optimal concentrations of Er and Yb were 1.0 % and 2.0%, respectively, and the concentration quenching was found to occur via the dipole-dipole interaction. Upconversion mechanism was discussed by using the dependency of emission intensities on pumping powers and considering the dominant depletion processes of intermediate energy levels for the red and green emission with changing the $Er^{3+}$ concentration. An energy transfer from $Yb^{3+}$ to $Er^{3+}$ in $CeO_2$ host was mainly involved in ground-state absorption (GSA), and non-radiative relaxation from $^4I_{11/2}$ to $^4I_{13/2}$ of $Er^{3+}$ was accelerated by the $Yb^{3+}$ co-doping. As a result, the $Yb^{3+}$ co-doping led to greatly enhance the upconversion intensity with increasing ratios of the red to green emission. Finally, it is revealed that the upconversion emission is achieved by two photon processes in which the linear decay dominates the depletion of intermediate energy levels for green and red emissions for $CeO_2:Er^{3+}/Yb^{3+}$ phosphor.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.12
• /
• pp.3748-3754
• /
• 2009

An integral head loss test in a test apparatus was conducted to simulate chemical effects on a head loss across a strainer in a pressurized water reactor (PWR) containment water pool after a loss of coolant accident (LOCA). The test was conducted during 30 days in the condition of a short spray, a long spray, and no materials with chemical effects. The result exhibited that the head loss was affected on amounts of the exposed materials according to spray conditions. XRD analysis of the collected precipitates showed that the precipitates were phosphate compounds. Comparison of the head loss with dissolved species concentration showed that high increase rate of the head loss resulted from the corrosion of aluminum and zinc but slow increase rate of the head loss resulted from the precipitates induced by Si, Mg, and Ca from leaching reaction at NUKON and concrete after passivation of metal specimens.

• Korean journal of applied entomology
• /
• v.29 no.3
• /
• pp.184-189
• /
• 1990

A nuclear polyhedrosis virus (NPV) of the tobacco cutworm, Spodoptera litura would be a promisible agent for the control of the insect. To develop a viral insecticide using S. litura NPV, effect of spray on soybean leaves, temperature, storage, an sunlight on the pathogenicity of the virus were studies as follows: Median lethal concentration ($LC_{50}$) of the virus sprayed on the leaves against the third and the fifth instar larvae were $1.301\times10^{4 PIBS}/ml$ and $1.087\times10^{5 PIBS}/ml$, respectively. On the concentration of $1.0\times10^{5 PIBS}/ml$, median lethal times ($LT_{50}$) were 7.3 days for the 3rd and 8.9 days for the 5th instar larvae. Stability of S. litura NPV was quickly decreased at the higher temperate than $60^{\circ}C$ and at the longer exposure to the higher temperature. Storage of the virus at $-20^{\circ}C$ was kept higher pathogenicity than $4^{\circ}C$ and $25^{\circ}C$. Viral activity was maintained more than 10 days in the sprayed-under leaves, but decreased at 3 day after spray in th sprayed-on the leaf surface when exposed the virus to sunlight.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.3
• /
• pp.127-138
• /
• 2016

Diesel vehicles should be equipped with urea-selective catalytic reduction(SCR) system as a high-performance catalyst, in order to reduce harmful nitrogen oxide emissions. In this study, a three-dimensional Eulerian-Lagrangian CFD analysis was used to numerically predict the multiphase flow characteristics of the urea-SCR system, coupled with the chemical reactions of the system's transport phenomena. Then, the numerical spray structure was modified by comparing the results with the measured values from spray visualization, such as the injection velocity, penentration length, spray radius, and sauter mean diameter. In addition, the analysis results were verified by comparison with the removal efficiency of the nitrogen oxide emissions during engine and chassis tests, resulting in accuracy of the relative error of less than 5%. Finally, a verified CFD analysis was used to calculate the interanl flow of the urea-SCR system, thereby analyzing the characteristics of pressure drop and velocity increase, and predicting the uniformity index and overdistribution positions of ammonia.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.7
• /
• pp.2267-2276
• /
• 1996

Twin-fluid atomization has been widely used in combustors and process industries because of its high performance and simple structure. Flow visualization and pressure measurements were conducted to investigate the effects of gas flow in twin-fluid atomization. Schlieren photographs showed that changes in atomizing gas pressure, altered the wave patterns, and the lengths of both recitrculating toroid (impinging stangnation point) nad supersonic flow region in the jet. A longer supersonic wave pattern like net-shape wqas observed as atomizing gas pressure increased. The disintegration phenomenon of liquid delivery tube. The variation of spray angles with gas pressures were obtained by visualization using laser sheet beam. Suction pressuresat the nozzle orifice exit and recirculating region are shown to be used to estimate the stable atomization condition of a twin-fluid atomizer.

• Fire Science and Engineering
• /
• v.24 no.4
• /
• pp.41-46
• /
• 2010

High strength concrete (HSC) has been mainly used in large SOC structures. HSC have superior property as well as improvement in durability compared with normal strength concrete. In spite of durability of HSC, explosive spalling in concrete front surface near the source of fire occurs serious problem in structural safety. Therefore, this study is concerned with experimentally investigation of fire resistance at high temperature due to fireproof material covering thickness in addition to concrete cover. From the test result, it was appeared that the use of fireproof material results in good performance for fire resistance and spalling prevention, and the optimal fireproof covering thickness is 1~3mm. On the other hand, the temperature was rapidly increased by explosive spalling within 30 minutes and showed very little rise caused by evaporation heat after then. It was also found that the void channel was remained at high temperature as PP fiber melts at about $200^{\circ}C$, and the pore pressure in concrete was decreased.