• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.416-422
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• 2007

The application analysis of bubble pump on the domestic solar water heater system is presented. The system investigated in this study is a passive device, self pumping and self regulating. It was test to use the bubble pump on solar water heater system. The test experiment has been taken on the existed vacuum tube about the efficiency, working fluid temperature and pressure and circulated power. In order to check the working temperature and working pressure effectively, the bubble pump was test separated from the solar water heater. The equipment consists of the bubble pump, heater and heat exchanger. The main structure of bubble pump was design depend on the character of two phase flow. The complete system was instrumented to measure pressures, temperatures and their relationship with the solar radiation intensity. The theory analysis of design bubble pump has been given and the experiment result analysis has been included in the paper.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.255-267
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• 2022

In this paper, noise characteristics of bubbles created by an orifice-type bubble generator are studied. In order to understand the overall bubble noise characteristics, the bubble noise spectra proposed by Strasberg and Blake, respectively, are examined, and an air injection experiment was performed in the large cavitation tunnel of KRISO to measure the bubble noise. The experiments were performed under a quiescent condition and flow conditions using 5 types of air bubble generator. From the measurement results, the characteristics of the bubble noise spectrum according to the experimental conditions are observed, and the effect of each parameter on bubble noise is analyzed by regression analysis. Finally, empirical models based on the regression analysis for bubble noise are presented, and it is confirmed that the estimated bubble noise is in good agreement with the measured results.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2309-2314
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• 2007

The application analysis of bubble pump on the domestic solar water heater system is presented. The system investigated in this study is a passive device, self pumping and self regulating. It was test to use the bubble pump on solar water heater system. The test experiment has been taken on the existed vacuum tube about the efficiency, working fluid temperature and pressure and circulated power. In order to check the working temperature and working pressure effectively, the bubble pump was test separated from the solar water heater. The equipment consists of the bubble pump, heater and heat exchanger. The main structure of bubble pump was design depend on the character of two phase flow. The complete system was instrumented to measure pressures, temperatures and flow-rates at various locations. The theory analysis of design bubble pump has been given and the experiment design has been included in the paper.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.220-223
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• 2002

This study investigated a lab-scale inducing method for efficient astaxanthin accumulation. As a model system. Haematococcus pluvialis was cultivated in 2 liter bubble-column photobioreactors. The astaxanthin - inducing results using high light irradiation were compared with that of the control experiment under standard irradiation (40 ${\mu}E/m^2/s$). After the late linear growth phase (> 20 days). high light energy (230 ${\mu}E/m^2/s$) was supplied to the culture broth for astaxanthin induction. As a result. the dr γ cell weight and the astaxanthin productivity were increased up to 68% and 215%, respectively. higher than those of the control experiment. This result indicates that bubble-column type photobioreactor is a good candidate for mass cultivation of H. pluvialis and high light irradiation is an efficient induction method for astaxanthin accumulation in lab-scale bubble-column photobioreactors.

• Journal of Korea Multimedia Society
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• v.21 no.3
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• pp.369-381
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• 2018

Nowadays a personalization algorithm is gaining huge attention. It gives users selective information which is helpful and interesting in a deluge of information based on their past behavior on the internet. However there is also a fatal side effect that the user can only get restricted information on restricted topics selected by the algorithm. Basically, the personalization algorithm makes users have a narrower perspective and even stronger bias because users have less chances to get views of opponent. Eli Pariser called this problem the 'filter bubble' in his book. It is important to understand exactly what a filter bubble is to solve the problem. Therefore, this paper shows how much Google's personalized search algorithm influences search result through an experiment with deep neural networks acting like users. At the beginning of the experiment, two Google accounts are newly created, not to be influenced by the Google's personalized search algorithm. Then the two pure accounts get politically biased by two methods. We periodically calculate the numerical score depending on the character of links and it shows how biased the account is. In conclusion, this paper shows the formation process of filter bubble by a personalization algorithm through the experiment.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.353-356
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• 2006

A set of solutions of the Navier-Stokes equation for the gas inside a spherical bubble with heat transfer through the bubble wall permits to predict correctly behavior of an ultrasonically driven bubble in aqueous solutions of sulfuric acid. Calculation results of the minimum velocity of bubble wall and the peak temperature and pressure are in excellent agreement with the observed ones. Further the calculated bubble radius-time curve displays alternating pattern of bubble motion as observed in experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.4
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• pp.46-52
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• 1988

The cavitation inception in oil hydraulic pipeline was investigated experimentally and numerically. In the experiment, negative pressures below-1 MPa(absolute pressure) were measured, associated with the transient flows in oil hydraulic pipeline. These experimental results show that the common hydraulic oil in the experimental pipeline withstands large tensions. In order to interpret the experimental results on cavitation inception, the growth of a spherical bubble in viscous compressible fluid due to a stepwise pressure drop was investigated by numerical analysis, and the critical bubble radius was obtained. The calculated value of the critical bubble radius corresponding to the negative pressure measured in the experiment is so small that the premised conditions about the bubble shape in the analysis is unsatisfactory. The physical significance of this calculated result implies the fact that there hardly exist free bubbles which can act as cavitation nuclei in the experimental pipeline.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.3
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• pp.127-130
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• 1987

The Cavitation inception in oil hydraulic pipeline was investigated experimentally and numerically. In the experiment, negative pressures below -1 MPa (absolute pressure) were measured, associated with the transient flows in oil hydraulic pipeline. These experimental results show that the common hydraulic oil in the experimental pipeline withstands large tensions. The growth of a spherical bubble in a infinite volume of viscous compressible fluid due to a stepwise pressure drop was investigated to obtain the critical bubble radius. The calculated value of the critical bubble radius corresponding to the negative pressure measured in the experiment is so small that the premised condition about the bubble shape in the analysis is unsatisfactory. The physical significance of this calculated result implies the fact that there hardly exist free bubbles which can act as cavitation nuclei in the experimental pipeline.

• Geophysics and Geophysical Exploration
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• v.26 no.1
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• pp.8-17
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• 2023

Various sources, such as wind, waves, ships, and gas leaks from the seafloor, forms bubbles in the ocean. Underwater bubbles cause signal scattering, considerably affecting acoustic measurements. This characteristic of bubbles is used to block underwater noise by attenuating the intensity of the propagated signal. Recently, researchers have been studying the large-scale release of methane gas as bubble plumes from the seabed. Understanding the physical properties and distribution of bubble plumes is crucial for studying the relation between leaked methane gas and climate change. Therefore, a water tank experiment was conducted to estimate the distribution of bubble plumes using seismic imaging techniques and acoustic signals obtained from artificially generated bubbles using a bubble generator. Reverse time migration was applied to image the bubble plumes while the acquired acoustic envelope signal was used to effectively estimate bubble distribution. Imaging results were compared with optical camera images to verify the estimated bubble distribution. The water tank experiment confirmed that the proposed system could successfully image the distribution of bubble plumes using reverse time migration and the envelope signal. The experiment showed that the scattering signal of artificial bubble plumes can be used for seismic imaging.

• Journal of the Korean Society of Combustion
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• v.7 no.1
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• pp.52-57
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• 2002

A numerical investigation using a commercial CFD program of the Inter-Phase Slip Algorithm has been carried out for detail characteristics of particle motions and bubble behaviors in a two dimensional fluidized bed. The bed simulated has been operated with three different distributor geometries, such as bubble cap, nozzle, and perforated plate types. Experiments using a slit-type two-dimensional fluidized bed and a cylinder-type fluidized bed have been performed in order to confirm the simulation model. In addition, the numerical results are compared with the wellknown correlation of bubble sizes and bubble rising velocities by Mori and Wen [1]. The simulation model that we applied is shown to be useful to understand the relation between bubble behaviors and distributor geometries.