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정운창(Jeong, Un-Chang),윤지현(Yoon, Ji-Hyun),양인형(Yang, In-Hyung),이유엽(Lee, You-Yub),오재응(Oh, Jae-Eung) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.12
MRE(magneto-rheological elastomers) is a material which shows reversible and various modulus in magnetic field. Comparing to conventional rubber vibration isolator, MREs are able to absorb vibration of broader frequency range. These characteristic phenomena result from the orientation of magnetic particles named carbonyl iron powder(CIP) in rubber matrix. In this paper, simulation on variation rate of shear modulus for anisotropic MRE due to volume fraction of CIP and an effective permeability model was applied to predict the field-induced shear modulus of MREs. Also, the variation rate of shear modulus for anisotropic MRE was derived using magneto-mechanical theory. Based on Maxwell-Garnett mixing rule, the increment of shear modulus was calculated to evaluate the shear modulus of MREs with column structure of CIP due to induced current. The simulation results on variation rate of shear modulus can be applied to the variable mechanical system of MRE such as tunable vibration absorber, stiffness variable bush and mount.
정운창(Un-Chang Jeong),오재응(Jae-Eung Oh) 한국소음진동공학회 2019 한국소음진동공학회 논문집 Vol.29 No.4
In this study, the objective and subjective sound quality of refrigerant-induced noise from air conditioner indoor units are conducted, particularly on the noise of two-phase flow, which is the main refrigerant-induced noise in air conditioner indoor units. To this end, Zwicker’s parameters were determined for an objective evaluation of two-phase flow noise via signal processing. In addition, virtual sound sources were produced such as the amplification of noise level, frequency shift, and increase/decrease in playback time. Sound quality evaluation was performed on the virtual sound sources, and a multiple regression equation was established using the objective evaluation parameters. Finally, a sound quality index with more than 90 % reliability is established through statistical processing and objective and subjective sound quality assessment of virtual sound.
가변형 Magneto-rheological Elastomer 동흡진기의 설계
정운창(Un-Chang Jeong),오재응(Jae-Eung Oh) 한국소음진동공학회 2019 한국소음진동공학회 논문집 Vol.29 No.4
Magnetic-rheological elastomer is a smart material that can change its shear modulus. This study suggested magneto-rheological elastomer (MRE)-based dynamic vibration absorber (DVA). The MRE-based DVA can change its stiffness instantly by controlling the magnetic field. To control the magnetic field, a magnetic flux generator was designed using electromagnetic finite element method analysis and the response surface method. Moreover, the shear modulus of MREs was evaluated by being applied to DVA, and the mass of the MRE-based DVA was calculated. Finally, a variable dynamic vibration absorber was manufactured to reduce the vibration according to changes in the magnetic field. The variable performance of the MRE-based DVA was conducted using current control.
소음원의 영향이 고려된 가상 세탁음 제작을 통한 드럼 세탁기의 음질 인덱스 구축
정재은(Jeong, Jae-Eun),양인형(Yang, In-Hyung),누룰 파와지(Fawazi, Noor),정운창(Jeong, Un-Chang),이정윤(Lee, Jung-Youn),오재응(Oh, Jae-Eung) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.6
The objective of this study is to determine the effect for the sound quality according to the noise source and to build the sound quality index of the laundry noise. In order to compare laundry noise among the influence of noise sources, we made virtual laundry noises by synthesizing an actual laundry noise and each noise source such as a dropping noise, water noise, motor noise and circulation pump noise. We conducted a listening test by customers using virtual laundry noises. As a result of listening test, we found that the dropping noise has a decisive effect on the sound quality of the laundry noise. We conducted the multi regression analysis of sound quality for the laundry noise using the statistical data processing. It is verified to the reliability of the multi regression index by comparison with listening results and index results of other actual laundry noises. This study is expected to provide a guide line for improvement of the laundry noise.