• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.364-369
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• 2012

The vehicle sound classified into driving sound due to power-train, operating sound due to electric motor like sunroof, door lock and electronic sound. These vehicle sound has various features depend on the characteristic of sound that user required. And it based on cultural and regional difference of user. In this study, the user required vehicle sound characteristics for luxury sedan was investigated in overall viewpoint. And virtual target sound was developed through the result of user preference investigation. Next, Jury test was carried out in Germany, USA and Korea for evaluating the target sound. And the regional and individual difference of preference was analyzed through the result of jury test. This result of research will be contributed to design of vehicle sound quality and target sound setting.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.8
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• pp.525-531
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• 2015

Driving sound is an effective element to promote the product identity of a vehicle by providing customers with attractive sound which reflects the concept of a vehicle. Recently, major automakers are focusing on the target sound setting so that the sound can represent the brand image as well as the unique concept of a vehicle. In this study, a new method of target setting for the driving sound will be introduced based on using formant filter and musical harmonics characteristics. In addition, a target sound suggested from this method will be realized and verified by using active noise control in vehicle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.461-466
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• 2012

Customers want to have more convenient and comfortable vehicle. Motor-on-caliper EPB(Electrical Parking Brake) System is one of the new systems for customer's convenience. It is applied for Midsize vehicle for reducing weight/price compared to cable puller type EPB. In this paper we studied sound quality improvement of motor-on-caliper EPB system. We developed the sound quality index and suggested the interior sound quality target value. To meet the target value cascading target was also suggested. EPB motor vibration level & sound radiation level, vibro-acoustic transfer function level from EPB to interior was defined. To find out effective way of sound quality improvement and find cascading target, TPA(Transfer Path Analysis) was carried out.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.2 s.21
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• pp.49-57
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• 2005

The target localization using the line arrays buried in the seabed is a difficult problem due to the complex sea bottom characteristics and need to compensate the wave propagation effect to localize the target accurately Sound speed mismatch in the seabed causes a bias in the target bearing estimation and induces the localization error. In this paper we describe a target localization method with improved accuracy of target bearing and localization by calibration the sound speed in the seabed. The proposed algorithm is verified through the ocean data.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.1
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• pp.48-57
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• 2014

It is suggested that the curvature trajectory be used to estimate the real-time moving sound sources and efficiently the robot estimating the sound sources. Since the target points of the real-time moving sound sources change, the mobile robot continuously estimates the changed target points. In such a case, the robot experiences a slip phenomenon due to the abnormal velocity and the changes of the navigating state. By selecting an appropriate curvature and navigating the robot gradually by using it, it is possible to enable the robot to reach the target points without having much trouble. In order to recognize the sound sources in real time, three microphones need to be organized in a straight form. Also, by applying the cross-correlation algorithm to the TDOA base, the signals can be analyzed. By using the analyzed data, the locations of the sound sources can be recognized. Based on such findings, the sound sources can be estimated. Even if the mobile robot is navigated by selecting the gradual curvature based on the changed target points, there could be errors caused by the inertia and the centrifugal force related to the velocity. As a result, it is possible to control the velocity of both wheels of the robot through the velocity PID controller in order to compensate for the slip phenomenon and minimize the estimated errors. In order to examine whether the suggested curvature trajectory is appropriate for estimating the sound sources, two mobile robots are arranged to carry out an actual experiment. The first robot is moved by discharging the sound sources, while the second robot recognizes and estimates the locations of the discharged sound sources in real time.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.195-202
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• 2016

In this study, a concept of active sound enrichment (ASE) control system was implemented and demonstrated for improving engine sound quality inside the cabin of a passenger car during acceleration. Unlike the active noise control cancels the noise for disturbance rejection, the ASE adds additional sound to the noise for tracking control. This approach requires a new algorithm to provide additional artificial sound to the original engine sound using active control strategy to achieve a target sound profile, which is predefined to satisfy required interior sound quality. The ASE algorithm was implemented in a digital controller dSPACE DS1401 and real-time control experiment was accomplished in an actual car. The ASE control results show that the actively enriched sound of each engine order against RPM tracks the target profiles precisely and quickly and improves the discontinuity, the level ratios and the sound pressure level of each engine order. Thus it is anticipated the ASE system can be applied for the improvement of the engine sound quality inside the cabin during acceleration.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.568-571
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• 2004

This research estimated the physical. mechanical characteristic and the character of sound absorption according to target void ratio of porous concrete and the mixing ratio of recycled aggregate for the valid utilization of recycled aggregate using waste concrete and sound reduction out of a road, a railway, a residential street, and a downtown area. As a result of the test, compressive strength tended to be a radical strength fall when target void ratio was $25\%$ and contents of recycled aggregate exceeded over $50\%$. Also, the character of sound absorption of porous concrete which used recycled aggregate using waste concrete was the most excellent when target void ratio was $25\%$, and the influence by contents of recycled aggregate was trivial. Therefore, when the strength and the character of sound absorption of porous concrete are considered, it is proved valid that proper target void ratio was $25\%$ and contents of recycled aggregate using waste concrete was $50\%$ or so.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1262-1269
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• 2008

Though multilayered foam-panel structures have been widely used to reduce sound transmission in various fields, most of the previous works to design them were conducted by repeated analyses or experiments based on initially given configurations or sequences. Therefore, it was difficult to obtain an optimal sequence of multilayered foam-panel structure yielding superior sound isolation capability. In this work, we propose a new design method to sequence a multi-panel structure lined with a poroelastic material having maximized sound transmission loss. Being formulated as a one-dimensional topology optimization problem fur a given target frequency, the optimal sequencing of panel-poroelastic layers is systematically carried out in an iterative manner. In this method, a panel layer is expressed as a limiting case of a poroelastic layer to facilitate the optimization process. This means that main material properties of a poroelastic material are treated as interpolated functions of design variable. The designed sequences of panel-poroelastic multilayer were shown to be significantly affected by the target frequencies; more panels were obtained at higher target frequency. The sound transmission loss of the system was calculated by the transfer matrix derived from Biot's theory.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.541-548
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• 2004

This study peformed an evaluation of the physical and mechanical properties and sound absorption characteristics of porous concrete according to the target void ratio and content of the recycled aggregate in order to reduce the noise generated in roads, railroads, residential areas and downtown areas and effectively utilize the recycled waste concrete aggregate generated as a byproduct of construction. The test results demonstrated that the difference between the target void ratio and the actual measured void ratio was less than 1.7% and that the tendency of the compression strength was to reduce rapidly when the target void ratio and the content of the recycled aggregate exceeded 25% and 50%, respectively. In addition, the sound absorption characteristics of the porous concrete using recycled waste concrete aggregate showed that the NRC was the highest at the target void ratio of 25% and the content of the recycled aggregate had very little influence on the NRC. Therefore, when considering the compression strength and the sound absorption characteristics of porous concrete, the proper target void ratio and the content of the recycled waste concrete aggregate are thought to be 25% and 50%, respectively

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.249-256
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• 1998

Design target values of transmission loss in a high-speed train wall are suggested by calculating the difference between interior and exterior noise levels of it. Exterior noise level distribution on the boundary of train wall is calculated by Sysnoise, with sound source input prepared by experiments. Two kinds of exterior sound sources are considered, the rolling noise of train wheels on the rail and the aerodynamic noise from the pantograph. Interior noise level is provided by high-speed design target. Transmission loss characteristics according to the frequency band are examined.