• Journal of ILASS-Korea
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• v.20 no.2
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• pp.76-81
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• 2015

Swirl flow has an impact on the stabilization of the flame by the recirculation flow, improvement of the combustion efficiency. The swirl flow in the gun type burner is created by the spinner which is inside the airtube that guide the combustion air. Burner has generally the combustion device composed electronic spark plug, injection nozzle, combustion device adaptor, and spinner. These inner components change the air flow behavior passing through airtube. So, this study analyzed exhaust flow characteristics of the gun type burner according to the ratio of airtube diameter. Turbulence characteristics by the spinner was mean velocity, turbulence intensity, kinetic energy, shear stress and flattness factor of the air flow of axial direction and tangential direction from the exit of the airtube.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.306-314
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• 1996

A seeder monitoring system was developed to solve the problems of mis-sowing and tube clogging in direct seeding machines, which have been one of the factors that reduce the performance of sowing operations. The system consisted of photo sensors, air nozzles, an air compressor, and a one-chip micro-computer based controller. The system was also equipped with the devices that perform the functions of self-checking and intermittent air injection for cleaning seed tubes. The performance of the system was tested in the laboratory and field. Using the well-cleaned rice seed, the average time for checking the mis-sowing was 1.37 seconds in the field and 1.2 seconds in the laboratory without any malfunction. Overall evaluation of the system indicated that the system can be utilized for seeding machines not only for paddies but beans and corns.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.105-110
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• 1999

This paper describes the inverter driven air-condetioner with power factor correction (PFC) circuit. By adopting PFC in the rectifier, we can reduce harmonic injection into power line, improve the efficiency and lower the total system cost compared to conventional inverter only. Also, system performance is improved by stabilizing the output voltage of PFC. In this paper, detailed design procedures for PFC are given, and the several merits with PFC are verified through the simulation and experiment.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.55-63
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• 2003

In a diesel engine, air-fuel mixture formation and ignition delay period have great influence on the performance of engine. Their main factors are combustion chamber shape, fuel injection system. air volume, air flow and so on. So, the combustion process in the cylinder is complex because of many factors which have direct and indirect effects on it. In this study, we take into consideration of scavenging pressure and scavenging temperature that are hewn as the main factor to the combustion process of two-stroke D.1. diesel engine. It is taken a picture of the combustion flame process for combustion chamber of re-entrant type and cylindrical type. So, it is applied to the basis data of combustion chamber design from an image analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.319-322
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• 2006

Rapid mixing of air-fuel (<1 ms) is needed to accomplish supersonic combustion. In this experiment, helium was injected laterally in to the Mach 1.92 air flow. 2 kinds of model, flat plate/cavity, were used in this experiment and images were taken by schlieren visualization. Pressure was affected by shock structure in the supersonic duct, and penetration height was increased by increasing J. Penetration height was higher in the cavity model than flat plate model.

• Journal of the Korean Society for Railway
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• v.3 no.3
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• pp.101-108
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• 2000

In this study, we tested hybrid pilot system combined with soil vapor extraction and bioventing methods on the contaminated railroad soil. So, we found out the remediability and operating conditions. Air permeability(k) and gas phase(O$_2$/CO$_2$/VOCs) level trend are very important to determine the remediation rate of the contaminated sites. Throughout hybrid pilot test on different conditions, the range of air permeability(k) was 1985∼1194 darcy. The tests results in hybrid system was appropriate on this test sites, and the suitable injection air flow rate was 3.5㎥/hr. So, we suggested a basic data for the remediation and management of contaminated railroad soil.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.91-94
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• 2003

A field pilot-scale demonstration of an enhanced SVE using hot air injection and extraction was conducted to remove diesel range compounds from subsurface soils at a site in J-city, Korea. The objective of demonstration was to evaluate field ISR by intrinsic microorganism after an application study of hot air-SVE technology and to calculate each first-order kinetic with soil temperature. TPH concentration of contaminated soil at the site was approximately 2, 000~11, 000 mg/kg (average 6, 900 mg/kg) with depths greater than 5 m bgs. The 1st-order reaction rate constants, k were 0.0438(@about5$0^{\circ}C$), 0.0564(@4$0^{\circ}C$), and 0.0685(@33$^{\circ}C$) d-1 respectively.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.572-579
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• 2002

The experimental measurements were carried out to examine turbulent disintegration characteristics ejecting from a counter-flowing internal mixing pneumatic nozzle under variable conditions of swirl angles and air pressures. The air injection pressure was varied from 60 kPa to 180 kPa and four counter-flowing internal mixing nozzles with axi-symmetric tangential-drilled holes at swirl angle of 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$, and 60$^{\circ}$to the central axis have been specially designed. The experimental results were quantitatively analyzed, focusing mainly on the comparison of turbulent atomization characteristics issuing from an internal mixing swirl nozzle. To illustrate the swirl phenomena, the distributions of mean velocities, turbulence intensities, volume flux, and SMD (Sauter Mean Diameter, or D$\sub$32/) were comparatively analyzed.

• Analytical Science and Technology
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• v.8 no.4
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• pp.787-792
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• 1995

A method for determination of ammonia-N in environmental water by air-segmented flow injection analysis using the colour reaction of phenol and sodium hypochlorite with ammonia was described in this paper. When the reaction temperature is $70^{\circ}C$ and the reaction residence time is 5 minutes, a sample frequency of $60-90h^{-1}$ can be achieved. The detection limit and relative deviation are $0.05mg.ml^{-1}$ and 4%, respectively. The recovery of this method is 96 - 110%, and the determination results of the method are greatly agreement with standard colorimetric method.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.246-253
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• 2005

The supernatant treatment of recovery process of raw materials of paper plant was studied using DAF (Dissolved Air Flotation) system. We investigated the removal efficiency (COD, SS and turbidity) of the DAF process. The effects of parameters such as A/S ratio, pressure, flotation conditions, coagulant concentration, mixing conditions, size and ratio of packing and nozzle type were examined. The results showed that the optimum A/S ratio and pressure were 0.058 and 4.5-5 atm, respectively. Injection times of pressurized water around 30 s and flotation times around 10 min appeared to be optimal for the DAF operation. Anion polymer addition improved the removal of COD, SS and turbidity. The smaller size and the more packing ratio were enhanced the removal efficiencies. The order of performance of nozzle was full cone > flat > assemble type.