• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.867-872
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• 2010

Numerical analysis has been conducted to investigate the fluid flow and fume mixing ratio characteristics of scattering fume in a push-pull ventilation system and optimally improve the flow patterns of scattering fume in the existing ventilation system. This ventilation system has been simulated by using commercial CFD code. In the case of the existing system, although the air is sprayed from air-curtain to prevent the fume from being scattered in upper hood, the improved air supply hood can remove the fume from the wide area in the high pressure. It is verified that the deeper plating storage is more advantageous. Also, by installing the shied around the plating storage, the scattering of the fume to the atmosphere was prevented effectively by surrounding flux.

• Journal of the Korean Society of Combustion
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• v.20 no.2
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• pp.40-45
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• 2015

This study is aimed to study combustion characteristics of low $NO_X$ burner using petroleum cokes as fuel. The petroleum coke, which is produced through the oil refining process, is an attractive fuel in terms of its high heating value and relatively low price. But petroleum coke is a challenging fuel because of its low volatile content, high sulfur and nitrogen content, which give rise to undesirable emission characteristics and low ignitability. The petroleum cokes burner is operated at fuel rich condition, and overfire air are supplied to achieve fuel lean condition. The low $NO_X$ burner is designed to control fuel and air mixing to achieve air staged combustion, in addition secondary and tertiary air are supplied through swirler. Air distribution ratio of triple staged air are optimized experimentally. The result showed that $NO_X$ concentration is lowest when overfire air is used, and the burner function at a fuel rich condition.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.2
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• pp.95-100
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• 2016

This study proposes the temperature compensation algorithm using thermopile detector for non-dispersive infrared Nitrogen gas sensor. From the output voltage of thermistor that is attached onto the infrared detector, the ambient temperature was extracted. The effects of temperatures on the properties of sensor module characteristics of narrow bandpass filter, optical cavity and infrared lamp, and air mixing gas have been introduced in order to implement the temperature compensation algorithm.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.7
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• pp.736-743
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• 2005

In this study, three different types of mechanical ventilation systems are compared based on their ventilation characteristics: tracer gas concentration decay characteristics, and ventilation effectiveness by calculating actual ventilation air flow rate. The experiments are performed by using a step-down method for measuring tracer gas. $CO_{2}$ gas, concentration in the model chamber. Application of a mixing factor, k, was used and measured values ranged from 0.68 to 0.77. The Type 2 ventilation system was found to have the highest ventilation effectiveness rather than the Types 1 and 3.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.133-139
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• 2005

In this paper, the ventilation performance of suspended particulates in indoor side was investigated by step-down method. Experiments were performed in function of mechanical ventilation types and locations of supply and extract air. The type 2 ventilation system shows the highest removal characteristics rather than other 2 types. It means that the displacement ventilation has also good decay rates of concentration compared to mixing ventilation.

• International Journal of High-Rise Buildings
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• v.8 no.1
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• pp.71-82
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• 2019

The purpose of this study is to evaluate the indoor air quality (IAQ) and energy benefits of a dedicated outdoor air system (DOAS) and compare them with a conventional variable air volume (VAV) system. The DOAS is a decoupled system that supplies only outdoor air, while reducing its consumption using an enthalpy wheel. The VAV system supplies air that is mixed outdoor and transferred indoor. The VAV has the issue of unbalanced ventilation in each room in multiple zones because it supplies mixing air. The DOAS does not have this problem because it supplies only outdoor air. That is, the DOAS is a 100% outdoor air system and the VAV is an air conditioning system. The transient simulations of carbon dioxide concentration and energy consumption were performed using a MATLAB program based on the thermal loads from the model predicted by the TRNSYS 18 program. The results indicated that when the air volume is large, such as in summer, the distribution of air is not appropriate in the VAV system. The DOAS however, supplies the outdoor air stably. Moreover, in terms of annual primary energy consumption, the DOAS consumed approximately 40% less energy than the VAV system.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.245-255
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• 2006

Dissolved air flotation is a solid-liquid separation system that uses fine bubbles rising from bottom to remove particles in water. In order to enhance the flotation velocity and removal efficiency of flocs in the flotation process, we tried to obtain pretreatment conditions for the optimum DAF process operation by comparing and evaluating features of actual floc formation and flotation velocity etc, according to coagulant types and conditions for flocculation mixing intensity by using PIA, PDA, and FSA. Accordingly, generating big flocs that have low density at low flocculation mixing intensity may reduce treatment efficiency. In addition, generating small flocs at high flocculation mixing intensity makes floc-bubbles smaller, which reduces flotation velocity, In this study, it was found that high flocculation mixing intensity could not remove the remaining micro-particles after flocculation, which had negative effects on treated water quality, Therefore, in order to enhance treatment efficiency in a flotation process, flocculation mixing intensity around $50sec^{-1}$ is effective.

• Journal of Industrial Technology
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• v.29 no.B
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• pp.107-113
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• 2009

For the environmental safety of the operating room and patient healthcare, the closed type rebreathing system is widely adopted. In order to reduce the anesthesia gas during surgery, the mixing ratio of anesthesia gas with breathing air should be precisely controlled. Generally, the breathing air passes through the vaporizer to mix the anesthesia gas, but there is a difficulty in controlling the mixing ratio precisely. In this paper, the stand-alone style vaporizer is designed and the operating characteristics are investigated. The vaporizer measures the temperature and pressure in the vaporizing chamber and chamber temperature is precisely controlled by proportional controlled heater. Exact quantity of anesthesia media is feeded by PID controlled peristaltic pump and vaporized gas is mixed with breathing air flow by PWM controlled solenoid valve. The experimental result shows that the vaporizer has an excellent command following performances that it can be applied to the low flow anesthesia system.

• Journal of Mechanical Science and Technology
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• v.16 no.10
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• pp.1336-1345
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• 2002

A triboelectrostatic separation system using a fluidized bed tribocharger for the removal of PVC material in the mixture of PVC/PS plastics is designed and evaluated as a function of electric field strength, air flow rate, and the mixing ratio of two-component mixed plastics. It consists of a fluidized-bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PS particles can be imparted negative and positive surface charges, respectively, due to the difference in the work function values of plastics suspended in the fluidized-bed tribocharger, and can be separated by passing them through an external electric field. Experimental results show that separation efficiency is strongly dependent on the electric Deld strength and particle mixing ratio. In the optimum conditions of 150 Ipm air flow rate and 2.6 kV/cm electric field strength a highly concentrated PVC (99.1%) can be recovered with a yield of more than 99.2% from the mixture of PVC and PS materials for a single stage of processing.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.3
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• pp.149-155
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• 2009

In this work a numerical study to find the characteristics of the internal flow and mixing process has been conducted in a static mixer used in the system of catalytic combustor of the fuel cell power plant. After introducing the model description and final governing equations the present numerical approach is applied to the analysis of static mixer, which may have one or more helical elements inside the circular tube by changing such various parameters as incoming mass flow rates and the number of helical elements. The results show that although the static mixer is efficient in mixing fuel and air, more optimization processes are required to achieve the appropriate mixing characteristics in front of the honeycomb type catalytic combustor used in the MCFC power plant