• Journal of Hydrogen and New Energy
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• v.34 no.1
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• pp.38-46
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• 2023

Carbon neutrality policies have been strengthened to reduce emissions, and the importance of technology road maps has been emphasized. In the global industrial boiler market, carbon neutrality is implemented through fuel diversification of methane-hydrogen mixture gas. However, various problems such as flashback and flame unstability arise. There is a limit to implementing the actual system as it remains in the early stage. Therefore, it is necessary to secure the source technology of methane-hydrogen hybrid combustion system applicable to industrial fields. In this study, control program for methane-hydrogen fuel conversion was developed to expect various parameters. After determining the hydrogen mixing ratio and the input air flow, the fuel conversion control algorithm was constructed to get the parameters that achieve the target oxygen concentration in the exhaust gas. LabVIEW program was used to derive correlations among hydrogen mixing rate, oxygen concentration in exhaust gas, input amount of air and heating value.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.92-103
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• 1999

The fuel spray behavior in the intake port of an electronic control port irijection gasoline engine has a strong influence on engine performance, exhaust emission and fuel consumption. Thus, in this study, fuel spray behavior and flow characteristics of the air assist gasoline spray injected into a suction flow in a simulated rectangular intake port have boon investigated. Macro-behavior of spray characteristics was investigated by means of visualization and the measurements of SMD and velocity were made by PDPA. For analysis the flow field with droplets size, droplets are classified five droplets size groups. As a result, the normal distance of suction flow increasing, the relatively large droplets distribution and SMD increase because small droplets easily follow suction flow. Near impinging wail, after impinging against the wall, secondary atomized small droplets of D < $30{\mu}m$ bound from the wall. And the increasement of suction flow progress to the large droplets of D > $100{\mu}m$ distribution. Therefore, SMD are apparently increased near impinging wall, Z/d = 9.0.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.9
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• pp.519-526
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• 2009

Environmental control system is adopted to control the thermal load from the avionic equipment in the reconnaissance pod which is mounted under a fighter aircraft, undergoing large and rapid environmental changes with the variations of flight altitude and velocity. In this study, an environmental control system was designed and built by adopting vapor compression cycle using R-124. The cooling performance characteristics of the system were measured varying operating parameters: thermal load in the pod, air mass flow rate through evaporator, condenser inlet air temperature, and air mass flow rate through condenser. The effects of the experimental parameters on the system performance were analyzed based on the experimental results. The problems on the designed system were also analyzed and the solutions were suggested to improve system efficiency and to obtain stable operation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.1
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• pp.22-33
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• 2020

Due to recent increased air traffic,, air traffic controllers in charge of en-route and approach control have faced huge increase in both workload and its intensity. The purpose of this paper is to analyze how much safety culture of air traffic controllers has effect on their complexity mitigation strategies during their duties. It could be expected complexity mitigation improve air traffic flow resulting in enhancing safety eventually. According to empirical analysis against air traffic controllers in civil aviation and air force in South Korea, it was proven safety culture had a statistically positive effect on complex mitigation strategies through safety behavior. In safety culture among air traffic controllers, intrinsic culture had a positive effect on extrinsic value of safety culture. Intrinsic value of safety culture led to air traffic controllers' safety behavior which created work complexity mitigation strategies. Among work complexity mitigation strategies, communication and cooperation was proven to be the most important factor effected by safety culture and behavior. It was implied that enhancing the intrinsic values of safety culture would cause to improve extrinsic safety culture and air traffic controller's work efficiency.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.2
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• pp.226-240
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• 1995

This research has a purpose to achieve experimental data used for design of ventilation systems necessary for indoor air quality control and their operation and management. For the study, spatial concentration distribution of indoor air quality according to pollutant site in a simplified model chamber. In low flow ventilation, flow pattern of indoor air was mainly influenced by diffusion and additionally, spatial distribution was formed by convection. Distribution of ventilation efficiency according to each pattern of model chamber was evaluated. It was confirmed that diffusion patterns of a pollutant among sites were formed, centering around main stream areas of supply and exhaust outlets.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.12
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• pp.811-820
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• 2007

A Study on the optimal design of the AIG(Ammonia Injection Grid) to improve the performance of DeNOx facilities in the HRSG(Heat Recovery Steam Generator) was performed using the CFD analysis. On the basis of the flow analysis results in the case that the AIG in the HRSG was not installed, the numerical analyses according to the positions of AIG, injection angles of nozzle and the control of ammonia injection quantity were carried out. The standard deviation according to factors was calculated for quantitative comparison. As the results, the AIG in the HRSG should be installed in the position that the uniform flow field shows through the exact flow analysis in the previous of the AIG design and installation. In the case the AIG has already been installed and non uniform flow distribution shows, it is recommended that flow correction device or KoNOx catalyst should be used. Otherwise, the control of ammonia injection angle or the ammonia injection quantity using the velocity profile analysis is demanded to accomplish the optimal performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.947-959
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• 2001

We propose a control scheme to control the indoor zone temperature via variable air volume (VAV) unit. To control the room temperature, state space model of the conditioned zone which is partitioned into nine artificial sectional regions is derived. The nonlinearity of the damper motion and actuator are considered for the practical use in the state space system description. The temperature control of the room temperature is performed by manipulating the degree of openness of the damper in relation to the local room temperature and the supplied air flow rate. In general, since a local temperature in the conditioned zone is measured, it is required to estimate the temperature values in each regions for the precise temperature control. We thus design a state observer to estimate the regional temperature, and use these values in the controller. The overall control system consists of the state observer based state feedback with the integral control. We compared the control results of the proposed scheme with those of cascade proportional and integral (PI) control, and showed that the scheme achieved precise control of the conditioned system.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.183-190
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• 2006

For continuously regenerative PM collecting system which adopted thermally stable SiC DPF and electrical heater which was placed upstream of the filter and driven by well constructed control logic, PM oxidation characteristics were investigated varying air flow rate, amounts of PM accumulated on the DPF and filter inlet temperature in order to get optimized PM regeneration performance. This study showed that the operating condition of air flow rate 70 lpm, high PM loading around 30g and filter inlet temperature $700^{\circ}C$ with heat insulation was effective in achieving high regeneration efficiency. Also, in this condition, we could decrease the electric energy consumption by reducing the regeneration time.

• Clean Technology
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• v.11 no.4
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• pp.181-188
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• 2005

Developed is the new gas-solid flow ball valve where air injection purging concept is applied for the control and the reduction of particle fouling. CFD analyses are conducted for investigating the interaction between gas-sold and air injection streams and the fouling phenomena in valve, and the analysis results are reflected in the design of valve geometry and air injection condition. Through the actual tests on designed ball valve, the present valve is shown to be superior in fouling reduction.

• 한국항공운항학회:학술대회논문집
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• 2006.05a
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• pp.25-31
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• 2006