• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1119-1125
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• 2010

Most of the sludge pre-treatment methods to improve the anaerobic digestibility of sludge are not practied in the fields with low economical efficiency. The venturi cavitation system (VCS) adopting hydrodynamic cavitation is simple and requires low energy. This research was conducted to investigate the optimum design and operating conditions of the VCS. The experimental results indicated that the optimum number of venturi in series was three, and the suction mode operation of the pump yielded 1.6 times higher pre-treatment efficiency per unit energy consumption than the discharge mode. The combination of venturies with different throat sizes did not affect the pre-treatment efficiency. Also, the parallel installation of the three in series venture unit yielded 30% higher pre-treatment efficiency per unit energy consumption than the single unit. Under parallel conditions, the solubilization efficiency was 5.6 mg ${\Delta}SCOD/g$ TS/kWh, which is higher than the previously reported value.

• Journal of Welding and Joining
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• v.29 no.3
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• pp.58-63
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• 2011

Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was compared with existing CP-type nozzle by TIG pulse welding in overhead position. As a result, CP-type occurs the wormholes in the overhead position, but the Venturi-type without the pore and formed a good bead appearance.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.169-179
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• 2023

Filtered containment system is a passive safety system that controls the over-pressurization of containment in case of a design-based accidents by venting high pressure gaseous mixture, consisting of air, steam and radioactive particulate and gases like iodine, via a scrubbing system. An indigenous lab scale facility was developed for research on iodine removal by venturi scrubber by simulating the accidental scenario. A mixture of 0.2 % sodium thiosulphate and 0.5 % sodium hydroxide, was used in scrubbing column. A modified mathematical model was presented for iodine removal in venturi scrubber. Improvement in model was made by addition of important parameters like jet penetration length, bubble rise velocity and gas holdup which were not considered previously. Experiments were performed by varying hydrodynamic parameters like liquid level height and gas flow rates to see their effect on removal efficiency of iodine. Gas holdup was also measured for various liquid level heights and gas flowrates. Removal efficiency increased with increase in liquid level height and gas flowrate up to an optimum point beyond that efficiency was decreased. Experimental results of removal efficiency were compared with the predicted results, and they were found to be in good agreement. Maximum removal efficiency of 99.8% was obtained.

• The KSFM Journal of Fluid Machinery
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• v.5 no.4 s.17
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• pp.47-53
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• 2002

The steam generator feedwater flow-rate in a nuclear power plant was estimated by means of artificial neural networks with the wavelet analysis for enhanced information extraction. The fouling of venturi meters, used for steam generator feedwater flow-rate in pressurized water reactors, may result in unnecessary plant power derating. The back-propagation network was used to generate models of signals for a pressurized water reactor Multiple-input, single-output hetero-associative networks were used for evaluating the feedwater flow rate as a function of a set of related variables. The wavelet was used as a low pass filter eliminating the noise from the raw signals. The results have shown that possible fouling of venturi can be detected by neural networks, and the feedwater flow-rate can be predicted as an alternative to existing methods. The research has also indicated that the decomposition of signals by wavelet transform is a powerful approach to signal analysis for denoising.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.711-714
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• 2008

The objective of this paper is to know the characteristics of pressure through a simplified typical carburetor used in small engines at the different throttle opening conditions. The carburetor is the device responsible for creating the right air-fuel mixture according to the different engine operating conditions. It is activated by the static or the dynamic pressure. The carburetor dummy is geometrically similar of LPG brush-cutter engine's diaphragm carburetor and is made of acrylic. Suction system gives body to crankcase vacuum using the vacuum pump and throttle opening conditions are controled by transfer device. Carburetor venturi throat and fuel charging tube diameter is each 20mm, 4.1mm. The result of the work presents an unprecedented phenomenon of suction pressure variation inside the carburetor venturi. It is predicted that these unprecedented pressure variation be caused by minor losses; sudden contraction or expansion, open or partially closed and so on.

• Journal of Drive and Control
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• v.16 no.1
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• pp.1-6
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• 2019

The use of micro bubbles in industrial fields has been increasing in the recent years., particularly micro-bubble sterilization and water purification effects. Various methods have been developed for the generation of micro-bubbles. Depending on the method of generating bubbles, the micro-bubbles can be roughly classified into saturation molding, cavitation and rotation flow types. The objective of this study was to use ventilated tube type as a method of generating micro-bubbles in order to purify large amount of water quality such as lakes and reservoirs. This method shows a difference in efficiency in which micro-bubbles are generated depending on the contact ratio of gas to liquid. The study also investigated the optimal gas liquid contact ratio by applying various orifice methods and investigated the optimum condition of micro-bubble generation by gas Based on this, a technology to develop a micro-bubble generator with a venturi type nozzle shape that has a high water purification effect was developed.

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.301-314
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• 2022

Various studies have been conducted on pedestrian-level wind environments around buildings. With regard to the speed-up mechanism of pedestrian-level winds, there are references to downwash effect due to the vertical pressure gradient of boundary layer flow and venturi effect due to flow blocking by the building. Two factors contribute to increase or decrease of downwash effect: change in twodimensional / three-dimensional air flow pattern (Type 1) and change in downwash wind speed due to building size that does not accompany change in airflow pattern (Type 2). Previous studies have shown that downwash effect has a greater influence in increasing or decreasing the area of strong wind than venturi effect. However, these considerations are derived from the horizontal mean wind speed distribution at pedestrian level and are not the result of three-dimensional flow field around the building. Therefore, in this study, Computational Fluid Dynamics using Large Eddy Simulation were performed to verify the downwash phenomena that contributes to increase in wind speed at pedestrian level.

• Korean Architects
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• v.5 no.1 s.17
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• pp.6-23
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• 1970

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.99-107
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• 1998

A test on venturi-type premixer of ASE120 engine combustor has been performed to evaluate its mixing performance. Cold air was supplied into the premixer through the fuel nozzle and mixed with the hot air from the compressor exit. The measured temperature of the mixed air was used to evaluate the mixedness. DOE(Design of Experiment) technique was utilized to make a test matrix of variables and to determine the optimum combination of variables, which was verified through a confirmation test.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.276-281
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• 2001

The KSR-III Main Propulsion System configuration of the liquid oxygen (LOX) feed line is analyzed. This feed line includes a tighter radius and cavitation venturi for flow mass flow-rate passive control. There were concerns that these configurations might generate a great flow distortion at the engine interface. Also both the pressure drop at the feed line and any presence of separation area are a great concern according to the propellant flow. To resolve these issues, a computational fluid dynamic analysis was conducted to determine the flow field in the LOX feed lines.