• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1999.10a
• /
• pp.245-250
• /
• 1999

In order to design micro-fan appropriately, flow chacracteristics and mechanics should be carefully considered. The present work concerns with design procedure for a micro-fan using NACA(National Advisory Committee for Aeronautics) airfoil series. The generation of fan profiles is carried out automatically by defining related parameters, which is also converted to CAD/CAM data automatically. The optimal parting surface for the mold of micro-fan is also calculated by analyzing the geometric data numerically. As a consequence, the high capacity micro-fan can be developed successfully with a high-quality and an improved efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.7
• /
• pp.895-906
• /
• 2000

A three dimensional linear frequency-domain lifting surface panel method was used for the aerodynamic analysis of axial flow type micro-fans. As proven by the duct modeling, the tip clearance of the micro-fans tested is large enough to ignore the calculated effect of the duct system. As the numerical results and experimental data agreed well in the operating point region, the method was applicable in the parametric studies to determine the design parameters of axial flow fans. Experiments on micro-fans were carried out based on KS B 6311. The newly designed micro-fan showed improvements in both static pressure rise and volumetric flow rate compared to the existing fans at a given operating condition. No detection of surging and the smooth characteristic curve proved the improvement in performance. To reduce the fan noise in the fan design, it was necessary to make use of the frequency spectrum analysis data. Measurement of sound pressure level for micro-fans was conducted based on KS B 6361 and KS A 0705. The peak - which occurs at blade passage frequency and its higher harmonics due to the fan noise - was not detected. This justifies the design methodology of the blade.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.961-966
• /
• 2001

Micro fans of randomly swept-blades were designed to provide C.P.U. in a personal computer with effective cooling in a very quiet mode. The proto--type axial micro-fans machined by a laser sintering machine were tested against manufactured products by comparing the performance and overall sound pressure level with spectral measurements in an environment suggested by ASHRAE and ANSI standards. The predicted OSPLs and directivity patterns of fans by iDesignFan software were in good agreements with measured data. The newly introduced fans of randomly swept-blades were proved to provide a very promising mode of low noise at small loading conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.1205-1208
• /
• 2006

This paper introduces a study for the noise reduction of a range hood for household. Generally, range hoods have a built-in sirocco fan from which rumbling noise is generated. Though the rumbling noise has low noise level. this noise makes most of the users nervous due to the its low frequency characteristics. For the purpose of noise reduction, in this study, a micro-perforated panel system is installed in the fan housing of range hood. From the experimental results, it is confirmed that the noise level emitted from the range hood is decreased over 2dB(A) in all frequency regions due to the effect of noise reduction by micro-perforated panel system.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.8
• /
• pp.1055-1061
• /
• 2002

A numerical and experimental study on the flow fields behind the fan outlet was carried out to improve the performance of a conventional fan-sink(fan and heat sink). Conventional fan-sinks have a heat sink of which fin configurations tend to increase the flow resistance, thus decreasing the performance and the cooling capabilities of a fan-sink. Lifting surface method is used for the prediction of flow fields behind the fan outlet. Oil-dot flow visualization technique is applied for the validation of numerical results. The numerical results and experimental data show agreement each other. A conventional heat sink is modified and redesigned using flow patterns behind the fan outlet. The newly designed heat sink has the configuration of curved fins which minimize flow resistance. It showed improvements in both cooling: capabilities and volumetric flow rate compared to the conventional one.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.3 s.168
• /
• pp.46-51
• /
• 2005

The vacuum cleaner motor runs at very high speed for suction power. Specially, motor power is provided by the impeller being rotated at very high speed. The centrifugal fan consists of the impeller, the diffuser, and the circular casing. Due to the high rotating speed of the impeller and small gap distance between the impeller and the diffuser, the level of noise in the centrifugal fan is at BPF(Blade Passage Frequency) and its harmonic frequencies. In order to calculate the sound pressure of centrifugal fan, unsteady flow data are needed. The cause of noise is obtained by dividing the fluid noise by exhaust flow of fan and vibration noise by rotational vibration of vacuum cleaner fan motor. Until now, an accelerometer has been used to measure vibration. However, it can not measure vibration in some parts of brush and commutator because of motor construction and 3-D vibrating mode. This study was conducted to perform accurate analysis of vibration and aerodynamic sound for fan motor in a vacuum cleaner using a laser vibration analyzer. A silent fan motor can be designed using the data measured in this study.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.9 no.3
• /
• pp.19-25
• /
• 2013

A new type axial flow fan with centrifugal sub-blades has been designed and fabricated in the present study. We investigated velocity and pressure distributions in downstream flow fields of the fan experimentally to detect the detailed flow characteristics of new axial flow fan and an existing axial flow fan. Two-dimensional velocity components were probed by applying a particle image velocimetry system and pressure distributions were measured by Pitot tube and micro-manometer. Our results show that the velocity and pressure distributions at the flow fields of the new fan are quite different from the existing fan, and that the centrifugal sub-blades in the new fan can improve the performance characteristics in view of kinetic energy.

• Journal of the Microelectronics and Packaging Society
• /
• v.10 no.1
• /
• pp.7-11
• /
• 2003

The semiconductor chips or electronic components generate heat, which causes malfunction of the parts when it was not cooled properly. Bulky heat sink and cooling fan are used to get rid of the heat. However, with this bulky system, it is hard to integrate the electronics system in a small scale. The cooling efficiency of the system depends on the surface area of the heat sink, thermal conductivity of the material and the method of integration. In order to develop a novel cooling system, a micro-heatsink with a large surface area while retaining small volume was fabricated by electroless deposition of gold/copper inside a Track-etched membrane. The structure of the micro-heatsink was investigated using SEM or optical microscope. It was also found that the micro-heatsink is more efficient than a flat copper plate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.1209-1211
• /
• 2006

This paper introduces an experimental study for the noise reduction of a ventilating fan system. For the purpose of noise reduction, conventionally an absorptive duct silencer filled with a glass fiber has been utilized. However, a glass fiber has some disadvantages like hygiene and secondary pollution problems. In order to overcome these problems, in this paper, a perforated duct silencer has been applied to the ventilating fan system. For the designing of a perforated duct silencer, the transmission losses for various perforated panel systems are measured and compared with its noise reduction performance.

• Korean Journal of Optics and Photonics
• /
• v.5 no.2
• /
• pp.204-211
• /
• 1994

Micro array lens systems are designed for a faximile or copy machine. The array type is hexagonal. Diameter of a lens is 0.16 mm and the distance of the center of the nearest neighbor is 0.192 mm. The magnitude of the lens system is 1:1. Working distane is 10.55 mm and the spot size is less than 0.04 mm radius on axis and 0.20 mm off-axis in case of single layer system. Working distance is 7.90 mm and the spot size is less than 0.07 mm radius on axis and 0.09 mm radius off axis in case of double layer system. Performance of single layer micro array lens system and double layer micro array lens system are compared with the characteristics of the ray fans.y fans.