• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.549-551
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• 1999

Recently, Several type of motors are used more widely in Fan system because of their low cost and high reliability. Therefore, the importance of fault detection and isolation of fan system significantly increases. The motor is a important factor bring out the fan system fault. So the problem of a fault detection for motor based on a parameter identification will be considered in this paper. After an introduction into fault detection with parameter estimation, a mathematical model for motor with special emphasis on motor itself. In the fault detection system, current and motor speed are used as parameter. Finally, simulation results are used to demonstrate the efficiency of the fault detection system.

• Journal of the Korea Safety Management & Science
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• v.17 no.4
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• pp.403-410
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• 2015

This study documents the 3-phase BLDC(Brushless DC) motor to improve conventional exhaust fan motor. Energy efficiency, noise, and air pollution reduction for the high-performance vibration of the BLDC motor has been used in many fields. It is necessary to achieve the information of rotor position for driving 3-phase type brushless DC motor. It is also necessary that the PWM control algorithm design for a MOSFET driver to control the motor speed control for each of three phases. BLDC motors for exhaust fan, we studied the controller and software. The control circuit and motor control program through which Exhaust fan up close and person can be used safely and protect the environment.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1981-1986
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• 2004

A cross-flow fan relatively makes high dynamic pressure at low speed because a working fluid passes through an impeller blade twice and blades have a forward curved shape. Therefore, the performance of a cross-flow fan is influenced 25% by the impeller, 60% by the rearguider and the stabilizer, 15% by the heat exchanger. At the low flow rate, there exists a rapid pressure head reduction, a noise increase and an unsteady flow against a stabilizer and a rearguider. Moreover, it is difficult to analyze the reciprocal relations of the cross-flow fan because each parameter is independent. Numerical analyses are conducted with different starting angles of the rearguider. Two-dimensional, unsteady governing equations are solved, using FVM, PISO algorithm, sliding grid system and ${\kappa}-{\varepsilon}$ standard turbulence model.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.982-992
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• 2001

In this paper, the performance of ventilation equipments in enclosed parking garages were investigated for several air distribution systems by numerical method. Air change effectiveness of the non-mixing system was 0.42. It meant that more supply air as much as the design supply air was needed to maintain good indoor air quality. In the high speed nozzle ventilating system which is most expensive one, air change effectiveness was 0.54. Therefore this system satisfied to ventilation design. In the jet fan ventilating systems, air change effectiveness for jet fan ventilating system-A with 18 jet fans and jet fan ventilating system-B with 6 jet fans in circulation mixing arrangement were 0.565 and 0.42 respectively. Jet fan ventilating system-C with 6 jet fans in transport mixing arrangement was 0.535. Jet fan ventilating system-A and jet fan ventilating system-C met the ventilation design. But velocity in jet fan ventilating system-A was over 2.0m/s which is inappropriate in human comfort. Therefore this system is not proper to ventilation. Jet fan ventilating system-C was the optimum one for enclosed parking garages among 5 systems examined in this paper.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.5
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• pp.321-327
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• 2016

This paper presents the application of airfoil impeller for enhancement of aerodynamic performance of a high speed centrifugal fan. Three airfoil impellers are proposed, considering the maximum thickness and the location of maximum thickness of the airfoil. C4 airfoil thickness distribution is applied to the three airfoil impellers. The impellers are evaluated using CFD (computational fluid dynamics) and suction power test. From the results, it is confirmed that flow separations on the pressure side of the impeller blades and the pressure side of diffuser blades are reduced when airfoil blade is applied to the impellers. It is also confirmed that with the centrifugal fan having airfoil impellers, there is an increase in fan efficiency by approximately 3% and reduction in specific sound level by approximately 1.3 dB(A).

• Journal of Communications and Networks
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• v.17 no.3
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• pp.231-240
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• 2015

To facilitate the base station planning in high speed railway communication systems, it is necessary to consider the functional relationships between the base station transmit power and space parameters such as train velocity and cell radius. Since these functions are able to present some inherent system properties determined by its spatial topology, they will be referred to as the power-space functions in this paper. In light of the fact that the line-of-sight path persists the most power of the received signal of each passing train, this paper considers the average transmission rate and bounds on power-space functions based on the additive white Gaussian noise channel (AWGN) model. As shown by Monte Carlo simulations, using AWGN channel instead of Rician channel introduces very small approximation errors, but a tractable mathematical framework and insightful results. Particularly, lower bounds and upper bounds on the average transmission rate, as well as transmit power as functions of train velocity and cell radius are presented in this paper. It is also proved that to maintain a fixed amount of service or a fixed average transmission rate, the transmit power of a base station needs to be increased exponentially, if the train velocity or cell radius is increased, respectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.144-149
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• 2016

This paper presents a power control method of high-speed single-phase BLDC motor. Most electric appliances require a power factor corrector (PFC) to mitigate grid current harmonics. However, the reactive components and power semiconductors in the PFC increase system cost and dimension. In this paper, a new motor drive system for a high-speed single-phase BLDC motor is proposed, which can decrease grid current harmonics without PFC by directly manipulating motor power and eliminating bulky electrolytic dc-link capacitor. Given that the proposed motor power control method does not require motor current controller, no current sensor is necessary. Moreover, the proposed algorithms can be easily implemented using a low-cost micro-controller. The effectiveness of the proposed power control method is verified by experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.792-797
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• 2010

Microwave oven and household cooker are devices of high voltage producer and high voltage storage batteries respectively for formation of necessary high frequencies at drive. These devices emit much heat energy because they are run at high voltages. Therefore, emitted heat energy becomes a factor that raises temperature of microwave ovens' main frame. In this research, the analysis shows the temperature distribution in microwave oven with the cooling fan drive conditions and the heat energy occurrence conditions. According to the analysis, as the speed of air outpoured in cooling fan increases, and the internal temperature decreases quantitatively. Also the inside temperature distribution was investigated by controlling heat energy emission.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.82-87
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• 2007

A cleaner has trouble with too much noise and power consumption. To solve these problems, the investigation for motors, which are the main component of vacuum cleaner, is required. However, it is difficult to analyze the flow by the experimental means because of the high speed of the fan rotation ranging from 30,000 rpm to 50,000 rpm. Moreover it takes much time to perform the numerical simulation for the flow. In this research, it is aimed to analyse the flow through the centrifugal fan which is believed to be a main noise source, by the computational method. The efficiency of the centrifugal fan is affected by friction loss, shock loss and so on. Those losses depend on factors like the velocity of impeller, blade shape and etc. Accordingly, the influence of the shape of impeller on the flow is investigated in this study. The computational analysis was done by changing impeller shapes. The flow around the centrifugal fan is simulated by applying the moving mesh. To verify the validity of the computation results, the air flow rate and the pressure field to the cleaner is compared with the experimental data. All simulations are performed by using commercial code SC/Tetra. The calculated results show good agreement with the experimental ones qualitatively and it is believed to be promising to use computational simulation in the improvement of the vacuum cleaner performance.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.522-525
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• 2008

A vacuum cleaner is the widely used home equipment. However, it has a trouble with too much power consumption. Most losses occur at the centrifugal fan. To remedy this trouble the investigation of motor, which is the main component of vacuum cleaner, is required. The flow characteristics around the high-speed rotating centrifugal fan which is influenced by the very low inlet pressure is quite different from a commonly used fan. Hence it is quite difficult to analyze the flow by the experimental means or by the numerical simulation. In this research, it is aimed to improve the air-suction performance of a vacuum cleaner through the flow analysis around a motor. The efficiency of the centrifugal fan is affected by blade shape, blade number, blade pitch, etc. The influence of the shape of impeller on the flow is investigated in this study. The flow around the centrifugal fan is simulated by applying the moving mesh. To verify the validity of the computation results, the air flow rate and the pressure field to the cleaner is compared with the experimental data. All simulations are performed by using commercial code SC/Tetra. The calculated results show good agreement with the experimental ones and it is believed to be promising to use computational simulation in the improvement of the vacuum cleaner performance.