• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.337-342
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• 2023

Since the electric vehicle uses an electric motor, problems have arisen as the driver hears the inherent noise of the motor or external noise, which was not a problem in the past, due to the overall lower noise environment than when using an internal combustion engine. Therefore, the purpose of this paper is to reduce the noise and vibration of electric motors for electric vehicles, and recently, to increase the speed of high-power, high-efficiency electric motors in a small size, and to develop low-noise motors, IPM motors are applied to produce 35KW electric motors for electric vehicles. A motor for low noise was designed and implemented. N-T Curve and efficiency map were confirmed as the final result of developing a 35KW low-noise motor for electric vehicles by applying the IPM motor applied in this paper. Based on 3500 rpm, Max Torque [Nm]: 121.15, Max Power [KW]: 44.04, and Max Efficiency [%]: 97.65, showing high efficiency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1429-1436
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• 2000

Suction muffler is one of the important component of a compressor for low noise level and high efficiency. The suction muffler which has the complicated flow path gives the higher transmission loss of sound, but lower efficiency of compressor results from the superheating effect and flow loss in suction flow path. It is shown that the computational analysis of fluid dynamics are very popular methods for designing of high performance and low noise suction muffler. To reduce the thermodynamic and flow loss in suction process, the flow path of suction muffler was estimated by FVM(Finite Volume Method) and verified by experiments. And to enlarge the transmission loss of sound, the acoustic properties inside the suction muffler was analyzed by FEM(Finite Element Method) and experiments. The smart muffler which gives a good efficiency and low noise character was developed by using those methods, and the effect was evaluated in compressor by experiment.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.10
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• pp.501-507
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• 2001

In this paper, new high-efficiency zero voltage switching (ZVS) AC-DC boost converter is proposed to achieve power factor correction by simplifing energy recovery circuit. A lot of high power factor correction circuits have been proposed and applied to increase input power factor and efficiency. Most of these circuits may obtain unity power factor and achieve sinusoidal current waveform with zero voltage or/and zero current switching. However, it is difficult for them to obtain low cost, small size, low weight, and low noise. The topology proposed to improve these problems can compact the devices in circuit and can achieve high efficiency ZVS AC-DC boost converter. Simulation and experimental results show that this topology is capable of obtaining high power factor and increasing the efficiency of the system.

• The KSFM Journal of Fluid Machinery
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• v.15 no.5
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• pp.37-41
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• 2012

High-efficiency and low-noise axial flow fan is developed by combining the FanDAS, a computerized axial fan design/performance analysis system, and CFD software(CFX). Based on fan design requirements, FanDAS conducts 3-D blade geometry design, quasi-3D flow/ performance analyses and noise evaluation by using through-flow analysis method and noise models for discrete frequency and broadband noise sources. Through the parametric studies of fan design variables using FandDAS, preliminary and baseline design is achieved for high efficiency and low noise fan, and then can be coupled with a CFD technique such as the CFX code for constructing final and optimized fan design. The FanDAS-CFX coupled system and its design procedure are applied to actual fan development practice. The FanDAS provides an optimized 3-D fan blade geometry, and its predictions on the performance and the noise level of designed fan are well agreed with actual test results.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.6
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• pp.539-545
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• 2012

Due to merits cost and efficiency, the transformer-less type photovoltaic (PV) inverters have been popularized in the solar market. However, the leakage current flowing through a parasitic capacitor between PV array and ground can cause adverse effect in the transformer-less PV system. In this paper, a bi-directional PV inverter with high efficiency and low noise is proposed for the PV system with an energy storage device. The proposed inverter is a transformer-less type and performs the bi-directional power control between dc sources and grid with high efficiency. In addition, the proposed inverter can suppress the leakage current and obtain low noise characteristic. Finally, 3-kW prototype was implemented to confirm validity of the proposed inverter.

• Journal of KSNVE
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• v.10 no.5
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• pp.873-879
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• 2000

Experimental investigation was conducted to study the effects of pitch angle maximum camber on the performance and noise of an axial-flow fan used in outdoor-unit of air -conditioner. For this study the axial-flow fan whose pitch angle can be varied was made and the Specific sound Pressure Level and other coefficients were measured using the anechoic fan tester. It is found that pitch angle affects more severly than the maximum camber on the fan performance. On the while the maximum camber affects much on the specific sound power level. Present results show that it is important to choose the optimum pitch angle and maximum camber to design the high-performance and low-noise axial-flow fan and specific noise measured in the anechoic fan tester can be sued effectively for the design of low-noise fan.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.533-539
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• 2004

The rotary compressor is widely used for the air conditioner because it is efficient and compact. In recent, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce noise level and to improve efficiency. The new type muffler that has two side discharge holes and dome shape represents much lower overall noise level, especially noise levels around 1kHz than the old type one that has one center discharge hole In acoustic spectra. Also it has higher air conditioner efficiency by lower oil discharging amount of a compressor than old type one that has rectangular shape and two side discharge holes. The noise reduction and efficiency improvement effects of the new type muffler were verified by tests for rotary compressors and air conditioners.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.445-448
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• 2001

Noise radiated from pile driving operation is one of major sources of community noise pollution and thus its operation method is strictly restricted by regulations. Although the drilling method is now used been commonly used in urban areas because of its activity, the benefit of low noise decreases due to high working cost. In the present work, noise characteristics of pile driving operation are carried out. Based on the study result, a low-noise pile cap for driven piles is developed in order to satisfy both the noise level restriction and the economical efficiency. Effects of pile cap are investigated by a scale model experiment, which is focused on the variation of impact force and sound pressure level. The results show a good possibility of noise reduction by an appropriately designed pile cap.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.244-247
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• 2006

Railway is superior to the other land transportation systems in aspects of energy efficiency and environmental problems. Energy efficiency and environmental problems are not considered during a preliminary feasibility study. Investment for railway is low because of low B/C in the economical efficiency analysis during the preliminary feasibility study. The body of this paper studies the data which can reflect environmental problems an assessment of environmental impact. Investment for railway would be higher when main environmental elements are considered before the choice of the railway lines.

• Design & Manufacturing
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• v.13 no.1
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• pp.61-67
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• 2019

The cooling unit of the industrial showcase consists of a compressor, a condenser and an evaporator. An axial fan is used to circulate the air to improve the efficiency of the heat exchanger. In the past, aluminum fans have been used, which have problems such as low performance, efficiency, high failure rate, and high noise. This study is to develop high performance, high efficiency plastic fan replacing aluminum fan. A major factor in determining the performance and noise of an axial fan is the angle and cross-sectional shape of the blade, which is suitable for raising the lift force, thereby controlling the vortex, which is the main cause of noise and performance degradation. In order to produce a high efficiency injection molded fan, it is necessary to develop a mold that minimizes the deformation of the injection process for the designed shape. In this study, we developed a high efficiency, low noise plastic injection fan with more than 11% performance improvement and noise reduction compared to conventional aluminum fan.