• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.121-128
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• 2017

For an investigation on the effect of the shape of electrodes in alkaline water electrolysis, two kinds of stack with circular and square electrode array are used to visualize both for behaviors of hydrogen bubble around the electrodes and for measurements of hydrogen production from these two stacks. The electrolytes for the hydrogen production experiment were applied for 20 wt%, 25 wt%, 30 wt% and 35 wt% of KOH alkaline aqueous solutions. As a result, the adhesion length of bubbles attached around the square electrode in the visualization experiment was found to be 1.7 times longer compared with the attached around the circular electrode. In the hydrogen production experiments, the volume of hydrogen production of the stack by using circular electrode array was approximately 3% more than that of the stack with square electrode array. These observations may be caused by the effect of the bubbles attached to the around the electrodes obstructing mass transfer such as hydrogen exhaust and electrolyte supply.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.20-27
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• 1998

The characteristics of the bubble adsorptive separation of CTAB(cetyltrimethylammonium bromide) and CuS precipitates was investigated. The Langmuir adsorption equation was adequate at very low concentration of CTAB, and the adsorption heat was determined from the batch analysis considering the bulk liquid accompanied between bubbles. The adsorption mechanism was explained with the collision adsorption between bubbles and precipitate particles. The optimum concentration ratio of (CTAB) to (CuS) for adsorptive separation was 0.1 and coincided with the ratio for the coagulation of particles. The collection efficiency was depended on pH and CTAB concentration but independent of the air flow rate, and the maximum efficiency was 0.0002. The selective separation of ZnS from the mixture of Cu-Cd-Zn sulfides was obtained by the bubble adsorption with CTAB.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1929-1932
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• 2005

We investigated the activities of autonomic nervous system during foot bathing. The effect of foot bathing was evaluated for four subjects by observing the characteristic of heart rate variability and bodily temperatures. The foot bathing was done with a commercial foot spa (Duches Co.) utilizing the four functional modes of the spa for two different temperatures of $35^{\circ}C\;and\;40^{\circ}C$. The four functional modes were clam, vibration, air bubbles, and both vibration and air bubbles. The experimental results showed that the temperature of foot and that of face right after foot bathing were not that different from each other. But, for heart rate variability, the activation of parasympathetic nerve showed distinctive increase at $40^{\circ}C$ of water temperature. In the analysis of heart rate variability for different functional modes, the change was not distinctive for different modes at $35^{\circ}$ of water temperature. However, at $40^{\circ}C$, the activation of sympathetic nerve showed distinctive increases with the increase in the complexity of functional modes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1351-1357
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• 2010

Water monitoring equipments using daphnia can be used to monitor the pollution levels of a country's main rivers. Such equipments should be capable of providing a prompt warning about increase in the contamination levels, which is evaluated on the basis of impulse number or toxicity index. As unmanned remote control equipments, they must provide reliable pollution monitoring results for each season and for the annual physical changes in each river. Two different equipments based on the impulse number and toxicity index showed different results for the operating rates and for the number of emergency checks required even though both were operated at the same conditions. The results are affected by many parameters such as the presence of any air bubbles and the microscopic pressure. The purpose of this study is to develop a method that can reduce the effect of bubbles or microscopic pressure on the monitoring data. We expect to achieve reliable monitoring data for water pollutants irrespective of the location of the equipment setup.

• Wind and Structures
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• v.26 no.4
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• pp.215-229
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• 2018

The appearance of a rivulet at the upper surface of a stay cable is responsible for rain-wind-induced vibration (RWIV) of cables of cable-stayed bridges. However, the formation mechanism of the upper rivulet and its aerodynamic effects on the stay cable has not been fully understood. Large eddy simulation (LES) method is used to investigate flow around and aerodynamics of a circular cylinder with an upper rivulet at a Reynolds number of 140,000. Results show that the mean lift coefficients of the circular cylinder experience three distinct stages, zero-lift stage, positive-lift stage and negative-lift stage as the rivulet located at various positions. Both pressure-induced and friction-induced aerodynamic forces on the upper rivulet are helpful for its appearance on the upside of the stay cable. The friction-induced aerodynamic forces, which have not been considered in the previous theoretical models, may not be neglected in modeling the RWIV. In positive-lift stage, the shear layer separated from the upper rivulet can reattach on the surface of the cylinder and form separation bubbles, which result in a high non-zero mean lift of the cylinder and potentially induces the occurrence of RWIV. The separation bubbles are intrinsically unsteady flow phenomena. A serial of small eddies first appears in the laminar shear layer separated from the upper rivulet, which then coalesces and reattaches on the side surface of the cylinder and eventually sheds into the wake.

• Journal of Broadcast Engineering
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• v.15 no.6
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• pp.715-722
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• 2010

As one of applications in augmented realities, this paper presents a bubble popping system utilizing a haptic vibro-tactile mouse. In this system, virtual bubbles randomly float in the 3D space. By using the vibro-tactile mouse grabbed by a user, the bubbles are popped when they are touched by the mouse in the 3D space. Then a bubble popping effect with addition mouse vibration is delivered to the user's hand through the mouse. The proposed system is developed on ARToolkit environment. Therefore, basic components such as a camera and a marker pattern are required. The systems is composed of a vibro-haptic mouse, a webcam, a marker pattern, a graphic bubble object, and graphic mouse. Mouse vibration as well as bubble fade-out effect is delivered. Therefore, the combination of visual and tactile bubble popping effects outperforms the usage of a single effect in the experience of augmented reality.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.166-170
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• 1975

Six kinds of canned processed fish-balls were collected from the local market of Korea in April, 1975 and frozen section was prepared with the fish-balls at $-25^{\circ}C$ , coincidently stained with PAS, sudan III, carbol-thionine and light green for histochemical observation on evaluation of materials and quality of the porducts. The results tased on morphological analysis were summarized as follows. Protein contents were showed the lowest level, ranging about $2.7-9.0\%$, while carbohydrate was contained from $58.1\%\;to\;75.2\%$ of the highest degree. Fat contents had a great variety depending upon the quality of porducts, showing $1.4-17.6\%$, and air bubble was contained from $14.4\%\;to\;21.1\%$, tended to a large quantity. In sample No. 6, the micro-organism3 were observed around the denaturated prtotein, carbohydrate, and air bubbles in canned fish-ball. When the other samples were incubated for 4 days at $37^{\circ}C$, bacterial colony was also formed around the denaturated protein, carbohydrate, and air bubbles in cavities.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.107-113
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• 2012

Pollutants in aquaculture system effluent mostly originated from solid wastes including uneaten feed and excreta of cultured species. In this research, DAF(Dissolved Air Flotation) unit is suggested as an integrated solid control unit especially as a form of IIBG(Inline Injection Bubble Generation) process in aquaculture system. Solid removal performance of DAF unit was examined under various operation and salinity conditions with turbidity and suspended solid. Solid waste removal efficiencies were found to be affected by operation conditions including saturator pressure, recycle ratio, coagulant concentration. Solid removal efficiency was higher under higher saturator pressure and recycle ratio under which condition larger number of bubbles is generated. Coagulant is thought to have important role in creating bubble-particle aggregate by showing better removal efficiency with higher concentration. However higher saline water showed less effectiveness in removing solids by DAF(IIBG). Application of DAF(IIBG) process also showed additional effect in phosphate removal and DO(Dissolved Oxygen) supply. Phosphate existed in polluted water was removed up to 46% after treatment, which is thought to attribute to aluminium phosphate precipitation. And DO concentration was found to increase over 50% of initial saturation concentration after the injection of micro-bubbles. Through experiments on solid removal from aquaculture effluent, DAF(IIBG) process is estimated to be effective solid control method. This property can help aquaculture system being installed and operated simply and effectively.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.827-834
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• 2020

Damage of tungsten due to helium ions of a PF device was studied. The tungsten was analyzed by SEM and AFM after irradiation. SEM revealed fine bubbles of helium atoms with diameters of a few nanometers, which join and form larger bubbles and blisters on the surface of tungsten. This observation confirmed the results of molecular dynamics simulation. SEM analysis after etching of the irradiated surface indicated cavities with depth range of 35-85 nm. The average fluence of helium ion of the PF device was calculated about 5.2 × 10¹⁵ cm^-2 per shot, using Lee code. Energy spectrum of helium ions was estimated using a Thomson parabola spectrometer as a function of dN/dE ∝ E^-2.8 in the energy range of 10-200 keV. The characteristics of helium ion beam was imported to SRIM code. SRIM revealed that the maximum DPA and maximum helium concentration occur in the depth range of 20-50 nm. SRIM also showed that at depth of 30 nm, all of the tungsten atoms are displaced after 20 shots, while at depth of higher than 85 nm the destruction is insignificant. There is a close match between SRIM results and the measured depths of cavities in SEM images of tungsten after etching.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1677-1688
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• 2020

In the sodium-cooled fast reactor, the steam generator is a heat exchange device between sodium and water, which may cause leakage, resulting in a sodium-water reaction accident, which in turn affects the safe operation of the entire nuclear reactor. To this end, the electromagnetic vortex flowmeter is used to detect leakage of the steam generator and its signal processing method is studied in this paper. The hydraulic experiment was carried out by using water instead of liquid sodium, and the sensor output signal of the electromagnetic vortex flowmeter under different gas injection volumes was collected. The bubble noise signal is reflected by the base line of the sensor output signal. According to the relationship between the proportion of the bubble noise signal in the sensor output signal and the gas injection volume, a signal processing method based on the energy ratio calculation is proposed to detect whether the water contains bubbles. The gas injection experiment of liquid sodium was conducted to verify the effectiveness of the signal processing method in the detection of bubbles in sodium, and the minimum detectable leak rate of water in the steam generator was detected to be 0.2 g/s.