• 한국항공운항학회지
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• 제23권2호
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• pp.51-56
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• 2015

This paper presents the procedure of drag prediction for EAV-1, based on a numerical analysis correlated to an in-flight test. EAV-1, developed by Korea Aerospace Research Institute, is a small-sized UAV to test a hydrogen-fuel cell power system. The long-endurance test flight of 4.5 hours provides numerous in-flight data. The thrust and drag of EAV-1 during the flight test are estimated based on the wind-tunnel test results for EAV-1's propeller performance. In addition, the CFD analysis using a commercial Navier-Stokes code is carried out for the full-scale EAV-1. The computational result suggests that the initial CFD analysis substantially under-predicts the in-flight drag in that the discrepancy is up to 27.6%. Therefore, additional investigation for more accurate drag prediction is performed; the effect of propeller slipstream is included in the CFD analysis through "fan disk" modelling. Also, the additional drag from airplane trim and load factor that actually exists during the flight test in a circular path is considered. These supplemental analyses for drag prediction turn out to be effective since the drag discrepancy reduces to 2.3%.

• 한국유체기계학회 논문집
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• 제18권6호
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• pp.71-75
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• 2015

The flow and noise characteristics of the regenerative blower are evaluated experimentally. To decrease the noise of regenerative blower at a high frequency, we arrange the impeller vanes unevenly by special formula. The uneven pitch formular consists of the combination of trigonometric function. The magnitude of degree between each vanes and the control parameters of trigonometric functions are main design parameters for the uneven pitch. The flow characteristics of even and uneven impellers are tested by the fan tester and compared each results. The efficiency of a blower is calculated by the axial power using a dynamo system. The noise property of designed impeller is measured in an anechoic room. In this study, we certify that the uneven pitch impeller is effective in the noise reduction at a high frequency.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.87-92
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• 2001

In automobile highway tunnels, in order to maintain a suitable environment for drivers and traffic, visibility in the tunnel must be maintained, and the concentrations of poisonous substances including carbon monoxide must be kept at or below allowable levels. For this reason, in long tunnels and tunnels with heavy traffic, ventilation facilities are installed. When the ventilation facilities are run at full capacity, the environment in the tunnel is obviously adequately maintained, but this consumes a great deal of electric power. Consequently, a central problem in highway tunnel ventilation control systems is to keep the pollution concentration at or below the allowable level, and thus provide a safe environment for traffic, while consuming as little electricity as possible. This paper introduces an operation method of longitudinal flow ventilation systems with jet-fan, dust collector and vertical ducts.

• 설비공학논문집
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• 제1권2호
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• pp.116-127
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• 1989

Research on reheating cooling cycle and its practical application have been made to prevent unequalized distribution of temperature and humidity of room due to lack of supply air volume and dewdrops on supply diffusers to be taken place as a result of lower temperature of supply air than that of dew point of room air in cooling cycle of constant air volume, single duct, single zone and draw-through fan type. In view of the fact that human body is insensitive to humidity, it is possible not only to construct the complete non-reheating cooling cycle by increasing the humidity point allowable with the deduction of occupant's sense of pleasantness minimizing, but also to get cooling cycle decreasing the reheating quantity if the humidity exceeds the point allowable. In addition, it is possible to save maximum 8% in electric energy for cooling in cooling system by constructing non-reheating cooling cycle instead of reheating cooling cycle and by increasing the relative humidity of room from 50% to 65% in case efficiency and air pressure of cooling system are low. It is also possible to get an optimum cooling cycle by determining the room humidity in consideration of pleasantness of occupants and conservation rate of electric energy if the cooling capacity, efficiency and total pressure of cooling equipment are fixed.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1729-1738
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• 2014

The offline verification of state of charge estimation, power estimation, fault diagnosis and emergency control of battery management system (BMS) is one of the key technologies in the field of electric vehicle battery system. It is difficult to test and verify the battery management system software in the early stage, especially for algorithms such as system state estimation, emergency control and so on. This article carried out the virtual environment modeling for verification of battery management system. According to the input/output parameters of battery management system, virtual environment is determined to run the battery management system. With the integration of the developed BMS model and the external model, the virtual environment model has been established for battery management system in the vehicle's working environment. Through the virtual environment model, the effectiveness of software algorithm of BMS was verified, such as battery state parameters estimation, power estimation, fault diagnosis, charge and discharge management, etc.

• 대한임베디드공학회논문지
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• 제11권1호
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• pp.15-20
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• 2016

Recently, the u-IT applications for plants and livestock become larger and control of livestock farm environment has been used important in the field of industry. We implemented wireless sensor networks and farm environment automatic control system for applying to the breeding barn environment by calculating the THI index. First, we gathered environmental information like livestock object temperature, heart rate and momentum. And we also collected the farm environment data including temperature, humidity and illuminance for calculating the THI index. Then we provide accurate control action roof open and electric fan in of intelligent farm to keep the best state automatically by using collected data. We believed this technology can improve industrial competitiveness through the u-IT based smart integrated management system introduction for industry aversion and dairy industries labor shortages due to hard work and old ageing.

• 전기학회논문지
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• 제59권3호
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• pp.604-608
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• 2010

An electric fan for cooling high density electronic devices is limited and operated in very low efficiency. The corona discharge is utilized as the driving mechanism for an ionic gas pump, which allows for air flow control and generation with low noise and no moving parts. These ideal characteristics of ionic pump give rise to variety applications. However, all of these applications would benefit from maximizing the flow velocities and yields of the ionic pump. In this study, a needle-mesh type ionic pump has been investigated by focusing on the radius of curvature of corona needle points elevating the ionic wind velocity and efficiency. It is found that the radius of curvature of the corona discharge needle point influences significantly to produce the ionic wind and efficiency. As a result, an elevated ionic wind velocity and increased ionic wind generation yield can be obtained by optimized the radius of curvature of the corona needle electrode.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.816-821
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• 2002

It is getting more important that energy efficiency and manufacturing cost of the electric motor in appliance. The SRM has been alternative choice. But acoustic noise and harshness in this motor was widely known. So this paper had been studied on the noise reduction of a SRM in air conditioner. This works include some parameters regarding to blown noise sources like a reluctance torque ripple, air gap eccentricity, Especially, it was focused on dynamic characteristics of the system based on mechanical viewpoint. It came to successful results. Besides, this gave us a validity of phase excitation in experimental measurements.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.105-108
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• 2002

For fabricating high T$\sub$c/ superconducting deposited film, novel electrophoretic deposition technique applied to deposit surface charged Particles on metal substrate with oxy d.c field has been studied. The electric properties of superconducting film don't improve easily because the particles of deposition film are deposited randomly on substrate and don't make orientation affected to its critical current density. In this paper, we studied conventional electrophoresis in addition to a.c field assisted for the improvement of BSCCO superconducting film with high orientation of deposition particles.

• 한국생산제조학회지
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• 제20권5호
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• pp.547-552
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• 2011

Drying process, corresponding to a final process in the area of food engineering, requires a lot of heat energy. Thus, the energy efficiency is very important for dryers. Since the energy efficiency of heat pump dryers is much higher compared to that of electric dryers or other types of dryers, most of large-capacity dryers are adopting heat pump. In this study, shapes, positions and number of air-circulating fans, guide vanes, air inlet, outlet and top separator were varied for optimization of the flow of a large-capacity heat pump dryer. In addition, fans were modelled with performance curves and porous media were assumed for foods and heat exchangers. The simulation results were applied to the 12-ton dryer and the velocity distributions were experimentally examined. Finally, uniform drying in time was successfully accomplished through frozen pepper experiment.