• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.44-50
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• 2012

A new type of chemical oxidation technology utilizing micro bubble ozone oxidizer and a pneumatic fracturing equipment was developed to enhance field applicability of a traditional chemical oxidation technology using hydrogen peroxide as an oxidizer for in-situ soil remediation. To find an efficient way to dissolve gaseous ozone into hydrogen peroxide, ozone was injected into water as micro bubble form then dissolved ozone concentration and its duration time were measured compared to those of simple aeration of gaseous ozone. As a result, dissolved ozone concentration in water increased by 31% (1.6 ppm ${\rightarrow}$ 2.1 ppm) and elapsed time for which maximum ozone concentration decreased by half lengthened from 9 min to 33 min. When the developed pneumatic fracturing technology was applied in sandy loam, cracks were developed and grown in soil for 5~30 seconds so that the radius of influence got longer by 71% from 392 cm to 671 cm. The remediation system using the micro bubble ozone oxidizer and the pneumatic fracturing equipment for field application was made and demonstrated its remediation efficiency at petroleum contaminated site. The system showed enhanced remediation capacity than the traditional chemical oxidation technology using hydrogen peroxide with reduced remediation time by about 33%.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.929-936
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• 2013

The saturator and injection nozzle are important facilities on the dissolved air flotation process. To increase the formation of micro bubble, it is required to improve the air dissolving performance in the saturator and keep the pressure uniform from the saturator to the nozzle. This study aimed to evaluate the performance of the saturator and the hydraulic effect of the nozzle and the pipe structure. The air volume concentration, bubble size and bubble residual time were measured in the test. The saturator, which had mounted with the spray nozzle, showed a good performance for bubble formation. Also, the characteristics of micro bubble formation were influenced by pressure uniformity and flow velocity through the orifice in the nozzle.

• Journal of Environmental Science International
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• v.24 no.1
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• pp.73-79
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• 2015

The objective of this work was to treat complex mal-odor of food waste with micro-bubbles from enhanced wet scrubber system, where the pilot plant was operated. Micro bubbles from the enhanced reactor of venturi scrubber were successfully generated through the air atomizing process with high velocity more than 60 m/sec and played an important role in the removal of mal-odor. Mal-odor was effectively changed into the micro-bubble and treated with washing chemicals together. Through establishing two series connection of the reactors, 85.2 % removal efficiency of complex mal-odor was obtained in case of average 940 times of input air. 0.35 kg/hr of sulfuric acid, 0.188 kg/hr of sodium hydroxide and 0.043 kg/hr of hypochlorite were injected for chemical washing.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.416-423
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• 2012

Liquid acquisition device in the liquid propellant supply system is required to protect entrance of gas bubble into the propulsion system. The device exploits the capillary effect of micro-sized poles in a screen and supplies pure liquid-phase propellant to the propulsion system. The bubble point is the most important performance parameter in the design of a liquid acquisition device. In this paper, performance parameters affecting the bubble point are identified through literature survey, in order to develop the experimental setup for the bubble point measurement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.3
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• pp.389-396
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• 2001

Direct numerical simulation of bubble growth and merger process on a single nucleation site during partial nucleate boiling is performed. The equations governing conservation of mass, momentum and energy are solved using a finite difference method combined with a level set method for capturing the vapor-liquid interface. The level set method is modified to include the effects of phase change at the interface and contact angle at the wall. Also, a simplified formulation for predicting the evaporative heat flux in a thin liquid micro-layer is developed and incorporated into the level set formulation. Based on the numerical results, the bubble growth and merger pattern and its effect on the heat transfer are discussed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.463-467
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• 2004

This paper presents the fabrication possibility of the micro actuator which uses a micro-thermal bubble, generated b micro-heater under pulse heating. The valve-less micropump using the diffuser/nozzle is consists of the lower plate, he middle plate, the upper plate. The lower plate includes the channel and chamber are fabricated on high processability silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The middle plate includes the chamber and diaphragm d the upper plate is the micro-heater. The Micropump is fabricated by bonding process of the three layer. This paper resented the possibility of the PCR chip operation by the fabricated micropump.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1196-1200
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• 2004

Micropump is very useful component in micro/nano fluidics and bioMEMS applications. In this study, a bubble-powered micropump was fabricated and tested. The micropump consists of two-parallel micro line heaters, a pair of nozzle-diffuser flow controller and a 1 mm in diameter, 400 ${\mu}m$ in depth pumping chamber. The two-parallel micro line heaters with 20 ${\mu}m-width$ and 200 ${\mu}m-length$ were fabricated to be embedded in the silicon dioxide layer of a wafer which serves as a base plate for the micropump. The pumping chamber, the pair of nozzle-diffuser unit and microchannels including the liquid inlet and outlet port were fabricated by etching through another silicon wafer. A glass wafer (thickness of $525{\pm}15$ ${\mu}m$) having two holes of inlet and outlet ports of liquid serve as upper plate of the pump. Finally the silicon wafer of the base plate, the silicon wafer of pumping chamber and the glass wafer were aligned and bonded (Si-Si bonding and anodic bonding). A sequential photograph of bubble nucleation, growth and collapse was visualized by CCD camera. Clearly liquid flow through the nozzle during the period of bubble growth and slight back flow of liquid at the end of collapsing period can be seen. The mass flow rate was found to be dependent on the duty ratio and the operation frequency. As duty ratio increases, flow rate decreases gradually when the duty ratio exceeds 60%. Also as the operation frequency increases, the flow rate of the micropump decreases slightly.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1089-1095
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• 2011

Numerical simulation is performed for nucleate boiling on a micro-finned surface, which has been widely used to enhance heat transfer, by solving the equations governing the conservation of mass, momentum, and energy in the liquid and vapor phases. The bubble motion is determined by a sharp-interface level-set method, which is modified to include the effect of phase change and to treat the no-slip and contact-angle conditions, as well as the evaporative heat flux from the liquid microlayer on immersed solid surfaces such as micro fins and cavities. The numerical results for bubble formation, growth, and departure on a microstructured surface including fins and cavities show that the bubble behavior during nucleate boiling is significantly influenced by the fin-cavity arrangement and the fin-fin spacing.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.4
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• pp.227-236
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• 2016

In the present experimental study, the effect of gas- and liquid-injected methods on the formation of bubble and liquid slug at the merging micro T-junction of a square microchannel with dimensions $600{\mu}m{\times}600{\mu}m$ was investigated. Nitrogen and water were used as test fluids. The superficial velocities of the liquid and gas were in the range of 0.05 - 1 m/s, and 0.1 - 1 m/s, respectively, where the Taylor flow was observed. The bubble length, liquid slug length, bubble velocity, and bubble generation frequency were measured by analyzing the images captured using a high-speed camera. Under similar inlet superficial velocity conditions, in the case of gas injection to the main channel at the merging T-junction (T_gas-liquid), the lengths of the bubble and liquid slug were longer, and the bubble generation frequency was lower than in the case of liquid injection to the main channel at the merging T-junction (T_liquid-gas). On the other hand, in both cases, the bubble velocity was almost the same. The previous correlation proposed using experimental data for T_liquid-gas had predicted the present experimental data of bubble length, bubble velocity, liquid slug length, and bubble generation frequency for T_gas-liquid to be ~24%, ~9%, ~39%, ~55%, respectively.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.1
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• pp.93-97
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• 2011

When freezing is present on ballast water, it can impose additional loads on the hull and effect on stabilization of ship. The anti-icing techniques of ballast water, therefore, are key criteria for ship safety. The existing anti-icing techniques of ballast tank are hull heating, water circulation and air bubble system etc. In this research, anti-icing performance tests for the ballast water using micro-bubble system and sea water circulation system have been carried out at two temperature conditions($-10^{\circ}C$ and $-25^{\circ}C$). Ambient temperature, sea water temperature and temperature of the inner parts of the ballast tank are measured and also ballast water conditions are checked during the model test. The applied anti-icing techniques of ballast water, such as micro-bubble system and sea water circulation system show good performance in the low temperature conditions.