• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.402-407
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• 2008

This study is performed to investigate heat transfer characteristics for thermal performance of fin-and-tube sensible heat exchangers under the low air flowrate according to fin geometry combination and coolant flowrate control. Fins and tubes of samples were separated between front row and rear row. Experiment results are plotted heat transfer rate of each row, heat transfer coefficient and sensible heat ratio against water flowrate control of each row. It is observed that thermal performance can be enhanced by fin geometry combination and water flowrate control of each row under the low air flowrate.

• Fire Science and Engineering
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• v.17 no.4
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• pp.105-110
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• 2003

In Part II, the temperature and smoke particle distributions of the extraction system, which yielded the best smoke removal performance among the three smoke control systems in Part I, for extraction flowrates of 0.6∼2.4 ㎥/s and two fire sizes of 200 ㎾ and 2 ㎿ were presented. The same numerical method was utilized to the same computational domain and configurations as Part I. It was shown that the extraction flowrate affects the smoke control performance significantly, and that a similar trend in improving the smoke removal performance with the increasing extraction flowrate between the two fire sizes. An extraction flowrate of 2.4 ㎥/s or higher was required for the temperature in the escape route less than $^{\circ}C$ for the given situations.

• Journal of Environmental Science International
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• v.8 no.4
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• pp.533-538
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• 1999

Fuzzy algorithm of automatic control for dissolved oxygen(DO) concentration in the aeration tank of an activated sludge process is proposed. Among variables repirometry and air flowrate are selected as significant input factors and the relationship with DO is estimated using a multiple regression model. The DO concentration and the amount of repirometry are fuzzified and the fuzzy rule base are determined. Using the fuzzy algorithm, the change of amount of air flowrate are determined and the change of amount of DO is derived.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.250-253
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• 2007

The purpose of this research is focussed on the numerical predictions of the heat and smoke propagations for a passenger train fire in an underground subway tunnel for different air supply and extraction flowrates. The analysis is performed for one of the stations on subway line #5 in Seoul under the emergency operation mode for different air supply and extraction flowrates. Five different the air supply and extraction flowrates are considered for the numerical analyses. The numerical results show that the air supply and extraction flowrates affect the smoke control performance significantly by improving the smoke removal performance for the balanced control of air supply and smoke extraction and for the unbalanced control with lager smoke extraction than air supply.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1780-1786
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• 1995

The main goal of the present study is to establish the techniques and methodolgies of turbine performance test through evaluating the objective turbine test piece, and checking the reliability of the self-developed test facility by performing a series of turbine tests under ambient temperature condition. A high speed coupling, a lubrication system and a test bed of the test facility were modified through a series of preliminary test in order to reduce the vibration and oil leakage. The flowrate control of the test facility and data acquisition were accomplished by using a software called "Labview" The measurement of shaft horse power and control of rotational speed according to the conditions of turbine rotation were performed by a separate system. The preliminary evaluation of the measured data suggests that the developed test facility and the test technique can be used reliably for the performance test of turbines with the minor improvement.provement.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.452-455
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• 2000

There are increasingly important financial incentives and environmental consideration to improve the effluent quality of wastewater from domestic and industrial users. The activated sludge process is a widely used biological wastewater treatment process. The activated sludge process is complicated due to the many factors such as the variation of influent flowrate and concentration, the complexity of biological reactions and the various operation conditions. Nowadays, not only suspended solids and residual carbon, but also nitrogen and phosphorous concentration of the effluent water must be taken into account for the design and operation of wastewater treatment plants. Also, the effluent quality to be met are more stringent. Therefore, an intelligent control approach is required in order to successful biological nitrogen removal. In this paper, the strategies for dosage of extra carbon in the anoxic zone and DO concentration in the aerobic zone are presented and evaluated through the simulation using the denitrification layout of the IWA simulation benchmark implemented by Matlab$\^$/5.3/Simulink$\^$/3.0. The control strategy to achieve sufficient denitrification rates in an anoxic zone. Methanol is used as an external extra carbon source. The external extra carbon source is required for the nitrogen removal process because nitrogen and organic concentration are fluctuated in the influent flowrate. The dissolved oxygen is calculated by So concentration in the activated sludge model NO.1. The air flowrate of each aerobic reactor is intelligently controlled to achieve the predefined setpoints. Air flowrate is adjusted by the fuzzy logic controller that includes two inputs and one output. The objective function for the optimization procedure is designed to improve effluent quality and reduce the operating cost.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.88-96
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• 2008

Effects of the duct inlet guide vane on the flowrate distribution characteristics of the defroster nozzle exit in a defrost duct system were investigated experimentally to design the optimum heating, ventilation and air conditioning (HVAC) system applied in an automotive compartment. A 3-dimensional hot-wire anemometer system was used to measure the velocity field in the vicinity of the defroster nozzle jet flow and the velocity distributions near the windshield interior surface. At first, two cases of with- and without-duct inlet guide vanes were considered as the test condition, and then three cases of the duct inlet guide vane were tested to determine the optimum guide vane shape and their positions. The arrangement of the duct inlet guide vanes has an effect on the improved flowrate distribution at the defroster nozzle exit and near the windshield interior surface. However, the application of the lots of guide vane to control the flow direction leads to increase the flow resistance, resulting in the decreased flowrate issuing from the defroster nozzle. The shape of the duct inlet guide vane affects not only the flowrate distribution between the driver side and the assistant driver side but also the reduction of the flow resistance in the defrost duct system.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.1 no.1
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• pp.56-61
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• 2001

Activated sludge processes are broadly used in the biological wastewater treatment processes. The activated sludge processes are complex systems because of the many factors such as the variation of influent flowrate and ingredients, the complexity of biological reactions, and the various operation conditions. The main motivation o this research is to develop an intelligent control strategy for activated sludge process (ASP). ASP is a complex and nonlinear dynamic system owing to the characteristic of wastewater, the change in influent flowrate, weather conditions, and so on. The mathematical model of ASP also includes the uncertainty which is a ignored or unconsidered factor from process designers. The ASP model based on Matlabⓡ/Simulinkⓡ is developed in this paper. And the model performance is examined by IWA (International Water Association) and COST (European Cooperation in the filed of Scientific and Technical Research) data. The model tests derive steady-state results of 14 days. In this paper, fuzzy logic control approach is applied to handle DO concentrations. The fuzzy logic controller includes two inputs and one output to adjust air flowrate. The objective function for the optimization, in the implemented evolutionary strategy, is formed with focusing on improving the effluent quality and reducing the operating cost.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2003.04a
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• pp.93-100
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• 2003

• Fire Science and Engineering
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• v.17 no.2
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• pp.56-61
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• 2003

The smoke removal rate from a room with an opening was investigated for different smoke control systems by using the large eddy simulation turbulence model of the Fire Dynamics Simulator. The decreasing rate of the particles randomly distributed in the 2m X 2m X 2.4m room was com-pared for the ventilation system, pressurization system and extraction system, and for the air flowrate of the ventilation system. Difference in the smoke removal rate among the three smoke control systems was small when the opening was closed. The pressurization system showed less smoke removal rate than the other two systems when the opening existed, and hence is not recommended for subway stations with large openings. It was also shown that a less flowrate in the ventilation system leads to a much longer smoke removal time.