• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.2
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• pp.36-39
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• 1986

The steady potential flow about a TP 620 hydrofoil, flying in air above a dynamic water surface. is calculated by the one dimensional theory as the clearance-to-length ratio tends to very small. The characteristics on water surfare effects of air supported TP 620 hydrofoil over water are compared NACA 4412, NACA 66 and plate. respectively. It is found that using the TP 620 hydrofoil is superior lift coefficients. Moreover for trailing edge shape of the hydrofoil, high lift coefficients at 1 Fmn can be obtained.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.703-710
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• 2009

The spectral irradiance and underwater transmission characteristics of a combined high-luminance light-emitting diode (LED) lights have been studied to evaluate suitable light sources for fishing lamps of the next generation. The wavelengths at which the irradiance was maximum were changed from 473, 501, 525, and 465 nm for blue, peacock blue, green, and white LED light to 475, 504 and 528 nm for [$F_{WB}$], [$F_{PB}$] and [$F_{GB}$] combined LED lights, respectively. If the irradiance characteristics at 400-700 nm wavelengths are set as 100%, the irradiance rates at 450-499 nm and 500-549 nm were decreased from 82.4% and 56% for blue, peacock blue LED light to 60.0%, 38.5% for [$F_{WB}$], [$F_{WP}$] combined LED lights. The underwater transmission characteristics of the combined LED lights were superior in the order [$F_{WB}$], [$F_{BP}$], [$F_{GB}$] in optical water type I; [$F_{WB}$], [$F_{PB}$], [$F_{GP}$] in optical water type II-III; and [$F_{GP}$], [$F_{WP}$], [$F_{PB}$] in optical water type 1. Setting the 10m depth underwater transmission characteristics of the combined LED lights in optical water type I at 100%, the transmission of water types II, III and 1 drops to 29.5%, 8.0% and 2.2%. Based on the distribution of spectral irradiance and underwater transmission characteristics calculated in optical water types II-III, where was the jigging ground for fishing lamps, the [$F_{WB}]$ and [$F_{GP}$] combined LED lights can be used as a suitable light sources for fishing lamps of the next generation.

• Journal of Environmental Health Sciences
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• v.38 no.2
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• pp.159-165
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• 2012

Objectives: This experiment was carried out to elucidate the effect of discharged water on the disinfection of $Phytophthora$ $capsici$ and evaluate the water characteristics. Methods: The dielectric barrier discharges (DBD) plasma reactor system used in this study consisted of a plasma component [discharge, ground electrode and quartz dielectric tube], high voltage source, and air supply. The effects of water characteristics such as pH, ORP and conductivity and the disinfection effect of discharged water were investigated. Results: Experimental results showed that in the process of discharge, the pH decreased, whereas ORP and electric conductivity increased. When the discharge time was 30 min, $Phytophthora$ $capsici$ of 2.94 log was disinfected within 300 seconds. Disinfection performance of stored discharged water was maintained for three days; however the disinfection effect vanished after five days. When $Phytophthora$ $capsici$ was injected into the discharged water, the disinfection effect decreased after two days. Conclusions: It is considered that the main disinfection parameters of the discharged water were chemically active species such as $H_2O_2$ and $O_3$ and high ORP.

• Proceedings of the KIEE Conference
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• 2000.07e
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• pp.26-28
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• 2000

A novel oxidant generation and ion precipitation cell with slits on parallel plate electrodes system has been proposed and an effect of the number and size of slits on ion precipitation and oxidant generation characteristics. As a result, with the electrodes with 48 slits($S=200{\times}60[mm^2]$. d = 1.5, 5.0 [mm]), it is found that the oxidant contained waters of 17.0 [ppmm] and 23.5 [ppmm] in acid water were obtained with 0.1 [wt%] NaCl dissolved tap water fed. And oxidant contained waters of 0.5 [ppmm] and 1.5 [ppmm] in alkali water were obtained with 0.1 [wt%] NaCl dissolved tap water fed. And the oxidant contained waters of 7.0 [ppmm] and 11.5 [ppmm] in mixed water were obtained with tap water and 0.1 [wt%] NaCl dissolved tap water fed. Consequently, very high ion precipitation and dense oxidant generation characteristics can be realized by having slits on the electrodes of conventional cells as these slits increase the electric fields and decrease the space charge limiting actions in interelectrode space.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1017-1024
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• 2009

In the past few decades, the rockfill embankment dam, which has superior workability and economy, has become a major trend. In Korea, most of the embankment dams are rockfill dams, but recently, in response to the demand for sustainable development and environmentally-friendly water resource development, the sand and gravel in streams has become a major construction material for dams, rather than the non-economic rockfill, and its application examples have also increased. In this study, a large triaxial test was performed, with construction samples of different maximum sizes, in parallel with the grading method at the 'B Dam' construction site in Korea, and the effects of the different maximum sizes on the strain of the dam construction material and on the shear strength characteristics were analyzed to provide the basic data for determining the strength characteristics of the coarse-grained materials by the maximum size.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.12
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• pp.579-585
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• 2003

Recently the utilization of the ozone dissolved de-ionized water(DI-O3 water) in semiconductor wet cleaning process to replace the conventional RCA methods has been studied. In this paper, we propose the water-electrode type ozone generator which has the ozone gas characteristics of the high concentration and high purity to produce the high concentration DI-O3 water for the silicon wafer surface cleaning process. The ozone generator has the dual dielectric tube structure of silent discharge type and the water is both used to electrode and cooling water. We investigate the performance of the proposed ozone generator which has the design goal of the concentration of 7[wt%] and ozone generation quantity of 6[g/hr] at flow rate of 1[$\ell$/min). The experiment results show that the water electrode type ozone generator has the characteristics of 8.48[wt%] of concentration, 8.08[g/hr] of generation quantity and 76.2[g/kWh] of yield and it's possible to use the proposed ozone generator for the DI-O3 water cleaning process of silicon wafer surface.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.3
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• pp.263-270
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• 2015

Using Diesel-Water Emulsion fuel in commercial diesel engine can reduce NOx and soot when it is injected through the injector. Because water in Diesel-Water Emulsion fuel is vaporized ahead of diesel particle and it cause decrease of combustion temperature. Furthermore, research about the possibility of applicating Diesel-Water Emulsion fuels to commercial diesel engine is demanded in order to prove that Diesel-Water Emulsion fuel is able to apply commercial diesel engine without any replacement of equipments. This research analyzed applicable possibility of Diesel-Water Emulsion fuels to commercial diesel engine's fuel injection system refering injection and spray characteristics. In this research, there are 3 experiments, that is injection quantity, spray visualization, and injection rate. Diesel-Water Emulsion fuel has less injection quantities compared to diesel fuel, and spray penetration length is more longer than diesel. Furthermore, emulsion fuels have less dispersed than diesel fuel. In conclusion, comparing with diesel fuel with only spray characteristics, Diesel-Water Emulsion fuel has bad effects about dispersion and vaporization.

• Geomechanics and Engineering
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• v.30 no.2
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• pp.201-210
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• 2022

This paper presents a study regarding the influence of various water levels on the characteristics of subgrade mud pumping through a self-developed test instrument. The characteristics of mud pumping are primarily reflected by axial strain, excess pore water pressure, and fine particle migration. The results show that the axial strain increases nonlinearly with an increase in cycles number; however, the increasing rate gradually decreases, thus, an empirical model for calculating the axial strain of the samples is presented. The excess pore water pressure increases rapidly first and then decreases slowly with an increase in cycles number. Furthermore, the dynamic stress within the soil first rapidly decreases and then eventually slows. The results indicate that the axial strain, excess pore water pressure, and the height and weight of the migrated fine particles decrease significantly with a low water level. In this study, when the water level is 50 mm lower than the subgrade soil surface, the issue of subgrade mud pumping no longer exist.

• Computers and Concrete
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• v.29 no.4
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• pp.209-217
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• 2022

In order to analyze the static and dynamic structural characteristics of the Obermeyer gate under overflow conditions, the force characteristics and vibration characteristics of the shield plate structure are studied based on the fluid-solid coupling theory. In this paper, the effects of the flow rate, airbag pressure and overflow water level on the structural performance of shield plate of air shield dam are explored through the method of controlling variables. The results show that the maximum equivalent stress and total deformation of the shield plate decrease first and then increase with the flow velocity. In addition, they are positively correlated with the airbag pressure. What's more, we find that the maximum equivalent stress of the shield plate decreases first and then increases with the overflow water level, and the total deformation of the shield plate decreases with the overflow water level. What's more importantly, the natural frequency of the shield structure of the Obermeyer gate is concentrated at 50 Hz and 100 Hz, so there is still the possibility of resonance. Once the resonance occurs, the free edge of the shield vibrates back and forth. This work may provide a theoretical reference for the safe and stable operation of the shield of the Obermeyer gate.

• Proceedings of the Korea Water Resources Association Conference
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• 1997.05a
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• pp.180-185
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• 1997