• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.8
• /
• pp.802-808
• /
• 2009

In this paper, the experimental study on the identification of noise sources and noise transmission paths was carried out for the cabin noise control of construction equipment. In order to investigate noise and vibration characteristics of cabin structure, sound absorption, transmission, and radiation tests were performed using cabin assembly models. The noise/vibration source levels were obtained from the real cabins of wheel loader and excavator. Using transfer functions of cabins and real cabins' source data, cabin noise was decomposed into airborne and structureborne noise transmissions. Finally noise sources and major transmission paths were successfully identified for wheel loader and excavator's cabins.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.04a
• /
• pp.84-89
• /
• 2009

In this paper, the experimental study on the identification of noise sources and noise transmission paths was carried out for the cabin noise control of construction equipment. In order to investigate noise and vibration characteristics of cabin structure, sound absorption, transmission, and radiation tests were performed using cabin assembly models. The noise/vibration source levels were obtained from the real cabins of wheel loader and excavator. Using transfer functions of cabins and real cabins' source data, cabin noise was decomposed into airborne and structureborne noise transmissions. Finally noise sources and major transmission paths were successfully identified for wheel loader and excavator's cabins.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.11 no.8
• /
• pp.364-373
• /
• 2001

The gear whine noise of vehicle transmission is directly correlated tilth the gear transmission error of mating gear The object of this study is to build up the synthesized countermeasure for the reduction of gear whine noire of vehicle transmission by developing the program which can be used to analyze and predict the vibrational characteristics caused by gear transmission error of mating gears of vehicle transmission. The developed mathematical models on the elements of transmission, for example, helical gear pairs, bearings and shafts are used and the modeling of the excitation forces are developed by the gear transmission error of mating gear which is defined by the amount of the elastic deformation of gear tooth & shaft and gear profile & lead errors. The mathematical system model of vehicle transmission developed by the substructure synthesis method Is also verified by the experiments.

• Journal of KSNVE
• /
• v.6 no.1
• /
• pp.89-95
• /
• 1996

If the transmission line voltage is greater than 500kV, audible noise (AN) and hum noise (HN) due to corona discharges on the conductor would be an important design factor for the conductor selection of transmission line. Also there is an aeolian noise: wind noise(WN) from the tower and the conductor due to wind. This paper presents the results of a statistical analysis of audible noise, hum noise, aeolian noise of 6-480mm$^{2}$ conductor bundle in KEPRI 765kV Test Transmission Line which was constructed to develop 765kV double circuit AC transmission line for the first time in the world. The result of the analysis shows that 6-480mm$^{2}$ conductor bundle and tower satisfy configuration the audible noise design criterion of 50dB(A).

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.5
• /
• pp.550-557
• /
• 2008

A transmission control cable connects the transmission control arm and the control lever mechanically and transfers control effort exerted by a driver to the transmission. It also transfers vibration generated by the engine to the passenger room through mechanical connection. To understand vibration and noise transfer mechanism and to further find a way to suppress the transmission of vibration effectively, a dependable dynamic vibration model is a necessity. A vibration model for a transmission control cable is developed and a simulation study has been conducted to obtain mode frequencies and a transmittability. The resonance frequencies obtained by an harmonic analysis is compared with the noise level measurement data. The measurement agrees with the simulation result thus ensures the reliability of the model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.241-246
• /
• 2001

This study considered the transmission loss and frequency characteristecs of window, and examined the transmission loss for each type of windows to design an optimized window for blocking external noise. Moreover this has detect the transmission loss which depending on the thickness and the types(single and fair glass) of window as several major factors of transmission loss design. With this result, this study suggests a window design guide for much silent condition which is below the level of noise standard recommended.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.5
• /
• pp.559-566
• /
• 2016

This study shows a development procedure and results of noise reduction for a new developed FF 8th speed automatic transmission. Based on planetary gear operating frequency analysis using PTA(planetary transmission analysis) program developed in 2012, It is expected that gear noise of the rear planetary gear set could be recognized easily in the concept design stage. Therefore, pRMC (planetary run many cases) analysis program that is developed in 2012 was applied to minimize the planetary gear noise level and noise distributions versus torque. To minimize noises coming from oil pump and final gears of a new transmission, several changes were applied, such as changing the clearance of double angular ball bearing, the oil pump rotor tooth number from 9 to 11 and the oil pump type from parachoid to megafloid and so on. Besides, stiffness values of the transmission case and the mount bracket were measured and reinforced properly. Finally, The total noise of the new FF 8th speed automatic transmission was developed successfully. Furthermore, E.O.L. testers also have been adapted to control the noise quality of automatic transmission assembly in the manufacturing factory. This paper could provide practical solutions to the automatic transmission NVH problems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.465-472
• /
• 2001

This paper describes the characteristics of wind induced noise from high-voltage overhead transmission facilities which include transmission lines. insulator strings. and aviation beacon spheres installed on the overhead ground wires. High-voltage overhead transmission lines generate an audible wind noise due to the alternate shedding of wind-induced vortices. The frequency spectrum from the insulator strings reveals its resonance peak. This resonance sound mechanism has been supposed the self-excitation phenomenon of the resonance and the velocity fluctuation. The booming noises from the aviation beacon spheres are detected and analysed.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.4
• /
• pp.612-615
• /
• 1996

Audible noise from corona discharge had been identified as one of the most important factors in the design of conductor configurations for high-voltage transmission lines. 500kV and above. Therefore this paper describes audible noise characteristics of 6 X 480mm conductor bundle in KEPRI 765kV Test Line and Corona Cage. Prediction formula for audible(corona) noise on a 765kV transmission Line was developed using this results.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.7
• /
• pp.1247-1253
• /
• 2007

The system phase noise spectrum distribution for COMS sensor data transmitter and receiver system was proposed in this paper. On the basis of the analyzed design parameter to reduce the phase noise effect in a receiver, the optimal system phase noise were proposed for raw, IRIT and HRIT data transmission that are sensor data, respectively. The proposed system phase noise provides the qualified transmission performance of sensor data and reduces the performance degradation due to phase noise generating in the transmission channel. Also the system phase noise spectrums are utilized in the design of frequency generation source for sensor data transmission and receiver system.