• The KSFM Journal of Fluid Machinery
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• v.9 no.3 s.36
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• pp.36-43
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• 2006

Recently, micro hydropower and it's useful utilization are taking a growing interest as a countermeasure of global worming by carbon dioxide and exhaustion of fossil fuel. The purpose of this study is to investigate the possibility of extracting micro hydropower wasted by a valve in water supply system using micro cross-flow hydraulic turbine. In order to fulfill the functions of controlling flow rate and pressure in substitute for the valve, air and water are supplied into an air suction hole which is installed on the side wall of micro cross-flow hydraulic turbine. The results show that in case of supplying a lot of air into the air suction hole, about 50% of flow rate and relatively high value of loss coefficient are controlled by the turbine. Moreover, including high possibility of applying the micro cross-flow turbine to water supply system, extended application of the turbine to the water discharge system of drainage and irrigation canal.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.392-397
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• 2009

Gravity pressure vessels find their use in the wet oxidation of sewage sludge, which can be defined as the oxidation of organic and inorganic substances in an aqueous solution or suspension by means of oxygen or air at elevated pressures and temperatures. Numerical analyses were carried out for investigating the flow characteristics and wet air oxidation in the reaction vessel with various conditions such as supply oxidation and the supply positions of oxidation, etc. Wet air oxidation is promoted in the vicinity of bottom in the reactor with increase of oxygen supply. Also, it is the best condition to the oxidation supply position of 150 m and oxidation flow of 0.06 kg/s in the GPV reactor as the remnant of sludge and creation of organic acids.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.5
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• pp.393-400
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• 2013

The air supply system has a significant effect on the efficiency of polymer electrolyte membrane fuel cell (PEMFC) systems. The performance and efficiency of automotive PEMFC systems are greatly influenced by their air supply system configurations. This study deals with the system simulation of automotive PEMFC systems using MATLAB/Simulink framework. In this study, a low-pressure operating PEMFC system adopting blower sub-module (turbo-blower) is modeled to investigate the effects of stack operating temperature and air stoichiometry on the parasitic power and efficiency of automotive PEMFC systems. In addition, the PEMFC net system efficiency and parasitic power of air supply system are mainly compared for the two types (low-pressure operating and high-pressure operating) of automotive PEMFC systems under the same net power conditions. It is suggested that the obtained results from this system approach can be applied for establishing the novel operating strategies for FC vehicles.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.10
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• pp.932-941
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• 2004

The objective of this study is to detect the multi-fault of HVAC system using a new pattern classification technique. To classify the effect of single-fault in determining the pattern, supply air temperature, OA-damper, supply fan, and air flowrate were chosen as experimental parameters. The combination of supply temperature, flow rate, supply fan and OA-damper were chosen as multi-fault conditions. Three kinds of patterns were introduced in the analysis of multi-fault problem. To solve multi-fault problem, the new pattern classification technique using residual ratio analysis was introduced to detect the multi-fault as well as single-fault. The residual ratio could diagnose single-fault or multi-fault into several patterns.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.2
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• pp.1-8
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• 1999

Extensive resistance tests for a passenger boat(now in service at Chung-Ju lake) have been performed in a towing tank to investigate the effect of an artificial air cavity attached to the hull bottom on the reduction of the ship resistance. The attached air cavity has been observed at various air sully rates, from which we have determined a proper shape of an air supply device. In order to prevent the supplied air from leaking near the bilge of the ship, longitudinal barrier strips have been attached to both sides of the device. The investigation on their effectiveness reveals that a cascade system of the air supply device reduces the resistance of the ship furthermore. Energy saving of more than 10% is achieved at the design speed in spite of the additional power necessary for the air supply.

• Journal of the Korean Solar Energy Society
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• v.25 no.2
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• pp.71-79
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• 2005

In this study, the ventilation performance of mechanical ventilation system in apartment House was analyzed through model test according to characteristics of air-vent. Then adequate interval of air-vent was suggested using computer simulation which will create comfort environment through improvement of ventilation performance in apartment house. The result of experiment with separation plate to prevent mixture of contaminated exhaust air with fresh supply air, the ventilation efficiency improved about 10%. The result of simulation with horizontal location of exterior air-vent, contaminated exhaust air is mixed regardless of interval variation. Consequently, mixture of the exhaust air can be prevented through locating the supply air vent on the top side and exhaust air vent on the lower side.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1227-1233
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• 2004

Air handling unit (AHU)'s air filter pressure difference is important for energy consumption and indoor air quality. Both energy Performance data and air filter differential pressure of AHU in real office buildings were monitored and analyzed to investigate quantitatively energy impact as dust buildup level on air filter grows. We also modeled and simulated CAV system using HVACSIM＋ program to examine the energy effect of dust buildup on filters. Through analysis of time series pressure drop data, the filter pressure difference rate has been increased due to cumulative supply air flow rate increase. As filter pressure drop increased to 1 inch water column, it is found that the supply air flow rate was decreased by 10%, the chilled water flow rate was increased by 5.9% and the pump energy consumption was increased to 5.9%.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.520-525
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• 2000

This research is to analyze the ventilation performance of mechanical ventilation systems for indoor air quality control and management. A ventilation performance with supply sites is evaluated in a test model chamber and office room. A $CO_2$ gas as a tracer gas is used to measure the ventilation performance. The ventilation performance is found to increase with increased the ventilation rate. The ventilation performance is analysed with 55% at the supply air of 570 lpm and with 20% at the supply air of 100 lpm in a test chamber. The ventilation performance is better than 15% comparing with natural decay at the supply of 570 lpm in office room.

• Journal of Korean Society of Rural Planning
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• v.24 no.3
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• pp.63-71
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• 2018

The comparison of demand and supply is needed for efficient ecosystem services planning. However, the gap between them cannot be analyzed as existing studies mainly dealt with only the supply of ecosystem services. This study compares the demand and supply of ecosystem services in Shiheung using environmental complaints and urban planning by semantic network analysis. As a result, 'air' and 'water' quality are magnified in demand, 'energy' and 'water' are crucial in supply. This result presents that citizen ask for the improvement of air quality in regulation services, although local government has plans for energy support in provisioning services. Periodic ecosystem services demand and supply monitoring will be the base of effective ecosystem services planning, which reduce insufficiency and surplus.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.324-329
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• 2020

The emergency evacuation support system provides a safe means of evacuation by preventing the inflow of smoke through the formation of a smoke shield curtain in fire situations and pressurizing fresh air to the inside of the smoke shield curtain. In this study, numerical analysis was performed to examine the effects of the hole size on the flow inside the smoke curtain. As the air supply size decreased, the flow rate through the air supply was formed relatively uniformly from the inlet to the outlet length of the emergency support system. In addition, the size of the air supply hole was more than 20 mm, the flow rate was very low near the outlet, so the air supply hole size should be smaller than 20 mm. In addition, the minor loss of the air supply hole was calculated to be K = 1.5 from the numerical results. Therefore, the proper design of an emergency evacuation support system is possible using the flow characteristics according to the size and minor loss of the air supply hole.