• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.14-16
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• 2010

A Duct surrounding a fan is known to reduce the tip loss and increase the fan performance efficiency. It also reduces the fan noise drastically. Ducted fan, therefore, has been focused to be a promising candidate for high efficient propulsion system. In this study, a small plane having ducted fan which can be tilted for vertical take-off and landing, is analyzed by CFD and its aerodynamic characteristics are compared. Ductef fan aircraft has small range of angle of attack for mininum drag and duct design should be focused for efficient ducted fan aircraft.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.270-274
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• 2001

Fans are widely used in household electrical appliances due to their easy usage and high performance for cooling capacity. However, the noise generated by these fans causes one of serious problems. LG electronics makes the intranet software for design and analysis of fan. Axial, sirocco and centrifugal fan can be designed and analyzed by using the IFD(Intranet Based Fans Design) software. In order to calculate the aeroacoustic noise of a fan, the numerical method, which can calculate the acoustic pressure at the blade passing frequency and its higher harmonic frequencies, has been developed. To calculate the unsteady resultant force of the blade, vortex method is used. This paper shows the overview of the software and validates the accuracy of predicted noise of fan.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.529-535
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• 2001

A centrifugal fan design code was developed and packaged together with iDesignFan／sup TM／ as new models. This code generate centrifugal forward curved and backward curved bladed impeller optimally. It also predicts the aerodynamic performance and the overall sound pressure level of the rotating fan by assuming steady blade loading. The overall sound pressure level is used as an input parameter from the third loop of the designing process to acquire the most silent fan for the given aerodynamic performance parameters. With this kind of inverse design concept used in the code, the period of designing a fan is significantly shortened. A centrifugal fan design code, developed in this study and included in iDesignFan／sup TM／, predicts the aerodynamic performance such as design flow rate and static pressure. The aerodynamic performance in the design and off-design conditions is calculated by using the mean line analysis. For the steady loading calculation, the lift force distribution in a blade is used.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.645-650
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• 2002

In this paper, new concept, low noise axial fan was developed. The fan was designed to operate at high-pressure condition inside the refrigerator. This fan - we call it Alpha fan - has small turbo blades at trailing edge of axial fan. These turbo blades make alpha fan operate at high pressure and low noise condition. In order to find out the optimal value of design parameters, 6-sigma method was used. The design parameters are ratio between inner and outer diameter, Height, Install angle and Install position of turbo blade. Optimal value of turbo blade was found out and the noise generated from this fan is reduced about 3dB(A).

• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.39-49
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• 2010

In this paper, a numerical study has been carried out to investigate the influence of jet fan design variables on the performance of a jet fan. In order to achieve an optimum jet fan design and to explain the interactions between the different geometric configurations in the jet fan, three-dimensional computational fluid dynamics and the DOE method have been applied. Several geometric variables, i.e., hub-tip ratio, meridional shape, rotor stagger angle, number of rotor-stator blades and stator geometry, were employed to improve the performance of the jet fan. The objective functions are defined as the exit velocity and total efficiency at the operating condition. Based on the results of computational analyses, the performance of the jet fan was significantly improved. The performance degradations when the jet fan is operated in the reverse direction are also discussed.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.4
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• pp.17-22
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• 1974

In this paper, the problem of finding tests to detect faults in combinational logic circuits is considered. At first, the method of fault detection in fan-out-free irredundant circuits is derived, and the result is extended to the fan-out redundant circuits. A fan-out circuit is decomposed into a set of fan-out-free subcircuits by cutting the lines at the internal fan-out points, and the minimal detecting test. sets for each subcircuit are found separately. And then, the compatible tests from each test set are combined maximally into composite tests to generate primary input binary vectors. By this procedure. the minimal complete test sets for reconvergent fan-out circuits are easily found and the detectable and undetectable faults are also classified clearly.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.805-813
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• 2012

A fan is the most common air flow machinery and is being used in various different industries such as for heavy machinery, home appliances and automobile. An axial fan has blades that force air to move parallel to the shaft about which the blades rotate. This type of fan is used in a wide variety of applications, ranging from small cooling fans for electronics to the giant fans used in wind tunnels. An axial fan generating large air volume used to cool equipments, but is less efficient. A sirocco fan is a efficient device for moving air by centrifugal force and can generate high pressure. Fans that affect the performance and noise of a product are important components. It is also a time and budget consuming equipment to develop a fan through physical experiments. In order to overcome this problem, we have designed and developed a fan simulator for axial and sirocco fan's fluid analysis using supercomputer. Performance and noise prediction based on datamining without numerical analyses is also developed for the conceptual design of a fan.

• Asia Marketing Journal
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• v.16 no.1
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• pp.133-148
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• 2014

People enthusiastic about human brands eagerly engage in fan communities to share their common interests with others. Although sharing one's enthusiasm towards the same celebrities can give thempositive senses of we-ness (in-group identity, togetherness, camaraderie) and belongingness, negative sides also exist such as schadenfreude and trash talk. Even though the studies addressing the negative sides of fan community are gaining significance, no prior studies formally examined the negative consequences of engaging in a fan community and their effect on one's well-being. Therefore, this current study aims to investigate how engaging in fan community negatively affects members' psychological well-being through schadenfreude and trash talk. Structural equation modeling analysis revealed that engaging highly in a fan community leads members to feel malicious pleasure at rivals' misfortunes and share negative opinions of rival human brands and fan communities. These negative consequences of fan community engagement ultimately lead to a lower level of psychological wellbeing, especially in the area of personal growth whereas fan community engagement has a direct positive effect on personal growth. By showing the negative influences of engaging in fan communities on members' well-being through schadenfreude and trash talk, the results of this study are expected to add depth to the existing literature.

• The Korean Journal of Community Living Science
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• v.24 no.3
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• pp.391-397
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• 2013

This study was conducted to define the characteristics of the fan according to the bed depth of rough rice for the silo used in South Korea. In this study, the characteristics like air flow resistance and air flow rate of the fan were investigated for an independent blowing system with 1 fan and the serial blowing system with 2 fans. In the experiment, the depth of rough rice was determined by 0, 1, 2, 3.2 and 4.5 m for an independent blowing system and the depth of rough rice was 4.5 m for the serial blowing system. The air flow resistances of the blowing fan and the suction fan in an independent blowing system were 55 mmAq and 88 mmAq respectively. In addition, the air flow resistance of the serial blowing system was 61% lower than the blowing fan and 28% lower than the suction fan of the independent blowing system. The air flow rates of the blowing fan and the suction fan in the serial blowing system were 516 $m^3/min$, 570 $m^3/min$, respectively. The former was 22% higher than the blowing fan while the latter was 29% higher than the suction fan in the independence blowing system. In other words, the serial blowing system was superior to the independent blowing system in blowing characteristics because the air flow rate was lower and air flow resistance was higher than the independent blowing system. However, the fan power consumption of the serial blowing system was more than 100% comparing with the independent blowing system.

• The KSFM Journal of Fluid Machinery
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• v.10 no.6
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• pp.7-16
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• 2007

An axial-type fan which operates at the relative total pressure of 671Pa and static pressure of 560Pa with the flow rate of $416.6m^3/min$ is developed with an optimization technique based on the gradient method. Prior to the optimization of fan blade, a three-dimensional axial-type fan blade is designed based on the free-vortex method along the radial direction. Twelve design variables are applied to the optimization of the rotor blade, and one design variable is selected for optimizing a stator which is located behind of the rotor and is used to support a fan driving motor. The total and static pressure are applied to the restriction condition with the operating flowrate on the design point, and the efficiency is chosen as the response variable to be maximized. Through these procedures, an initial axial-fan blade designed by the free vortex method is modified to increase the efficiency with the satisfaction of the operating condition. The optimized fan is tested to compare the aerodynamic performance with an imported same class fan. The test result shows that the optimized fan operates with the satisfaction of restriction conditions, but the imported fan cannot. From the experimental and numerical test, they show that this optimization method improves the fan efficiency and operating pressures of a fan designed by the classical fan design method.