• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.5-11
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• 2001

Acoustic characteristics of the wedge-shaped anechoic tiles, used as absorbing lining materials for an anechoic water tank, were investigated for different wedge-apex angles. The anechoic tile base has the dimensions of 400mm x 385mm x 15.5mm. In order to investigate anechoic effect, the wedge-apex angles 30° and 60° were selected by using a ray-tracing method. The reflection loss of the anechoic tiles with and without wedges were experimentally studied at normal incident sound waves in water. In this experiment, the reflection loss of wedge-shaped anechoic tiles with the optimum wedge-apex angle 30° is larger than one with the angle 60° and one without wedges. The experimental results show that the wedge-shaped anechoic tiles with the wedge-apex angle 30°, optimized by using ray-tracing method, turn out better absorbing lining materials of an anechoic water tank.

• The Journal of the Acoustical Society of Korea
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• v.33 no.3
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• pp.163-173
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• 2014

Sound propagation algorithm for a sonar simulator is required to run in real-time and should be able to model the range and depth dependence of the Korean ocean environments. Ray model satisfies these requirements and we developed an algorithm for range-dependent ocean environments. In this algorithm, we considered depth-dependence of sound speed through rays based on a rectangular cell method and layer method. Range-dependence of sound speed was implemented based on a split-step method in the range direction. Eigen-ray is calculated through an interpolation of ray bundles and Gaussian interpolation function was used. The received time signal of sonar was simulated by Fourier transform of eigen-ray solution in the frequency domain. Finally, for the verification of proposed algorithm, we compared the results of transmission loss with other validated models such as BELLHOP, SNUPE, KRAKEN and OASES, for the Pekeris waveguide, wedge, and deep ocean environments. As a result, we obtained satisfactory agreements among them.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.727-732
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• 2014

The goal is to find the position of the sound source with the TRM at reflections and refractions environment. The Fermat's principle applied to the ray tracing method are expected to follow the acoustic path in order to obtain acoustic distance and transmittance to. Utilizing them in the TRM was confirmed rear reflectance affect on estimated position, resolution and side lobe. And the TRM performance were superior to one of the beam forming techniques.

• The Journal of the Acoustical Society of Korea
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• v.14 no.3
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• pp.82-89
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• 1995

A sound field simulator is constructed to obtain the sound field paramaters such as the magnitudes and directions of early reflections with moderate efforts. The proposed simulator is based on the hybrid ray tracing method that traces rays reached the listener position and convert them to image sound sources. By this approach, we can obtain the directional impulse response relatively easily with minimum casts. Simulation experiment results of several performace places are reported to how the versatility of the proposed simulator system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1043-1047
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• 2007

Community Noise has been great concerned in public. Especially, the road traffic noise has affected too much damage on quiet living environment. In this paper, the noise barrier and reducer effect on the street has been analyzed by using the ray tracing method. The outcome of the analysis has been compared to the measurement at the street near the highway. It turns out that noise barrier and reducer decreases noise level by 7dB(A).

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.519-522
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• 2002

컴퓨터에 의한 실내음향 예측에 있어 확산반사의 고려는 매우 중요한 요소의 하나로 간주된다. 지난 수년 동안 음선추적법을 이용하여 실내음향을 예측하는 경우에 확산 반사를 고려하기 위한 방안들이 다양하게 제시되었으나 경면반사를 근본으로 하는 영상법에서는 확산 반사를 고려하기가 어려운 것으로 알려져 있다. 본 연구에서는 컴퓨터 그래픽 분야에서 제안된 확장 라디오 시티법을 적용하여 영상법에서 확산반사를 고려하는 방안을 제시하였다. 부분적으로 확산성을 갖는 반사면에서의 음향에너지 반사는 확산반사와 경면반사의 형태로 나누어 볼 수 있으며 반사의 횟수를 거듭함에 따라 확산-확산, 확산-경면, 경면-확산, 경면-경면의 형태로 반사에너지의 전환이 이루어진다. 본 연구에서는 고차 형태계수의 개념을 이용하여 이 네가지 형태의 반사음전달과정을 모두 고려할 수 있도록 함으로써 실내의 벽면을 부분적 확산반사의 특성을 갖는 반사면으로 모델링 할 수 있도록 하였다. 본 논문에서는 확장라디오시티법의 개념과 이에 따른 고차형태계수의 근사 계산법을 제시하고 고차형태계수가 실내음향 씨뮬레이션의 결과에 미치는 영향 등을 분석해 보았다. [본 연구는 한국과학재단 특정기초 연구 (과제번호 1999-1-310-004-3)의 지원에 의한 연구결과의 일부임]

• Journal of KSNVE
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• v.10 no.2
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• pp.240-246
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• 2000

One of the widely accepted methods for evaluating the interior sound quality of automobiles is Articulation Index(AI). The AI actually measures the articulation level of the sound in the vehicle cabin as passengers talk to one another. In this study, the effect of two different absorption materials inside the cabin on AI has been investigated by ray-tracing method : one is firewall, the other is celling. It turns out that the back seat location is found to be strongly dependent on the type of absorption materials treated at the celling, since the sound absorbing area is different due to the location and the firewall is situated in the "Reverberation Radius". The proposed methdo could be used to improve the sound quality of automobiles at the design stge.sign stge.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.345-349
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• 2008

In this paper, environmental noise analysis was performed for large power plant and desalination plant. Ray tracing method was used to predict inside noise of turbine building. It is important to design the plant with the allowable noise level. To improve the accuracy, main noise sources were estimated based on the field data. As the results of analysis, it was concluded that noise levels slightly exceed the specified noise limit in turbine building inside. In order to reduce the noise level, adding sound-absorbing materials to inside wall of turbine building was suggested and verified with the confirmed analysis model.

• Journal of KSNVE
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• v.9 no.6
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• pp.1131-1136
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• 1999

NIC@E is the software developed by authors. The program provides the noise level in outdoors due to various noise source types : construction machines including blast sources, railroad vehicles and automobiles. It operates in the Windows system. In this paper, a highway traffic noise has been evaluated using various types of approach : Ray-tracing method, NIRI method, JAS method. In order to compare the noise estimation performance for various models, a measurement is conducted on a 8 lane express highway at the distance of 25 m and 50 m from the lane. The result shows that the ray tracing and JAS model predict the measured value well within 2dB deviaton. The NIRI model, however, underestimates the highway noise level, as the distance between the source and receiver increases.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.7
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• pp.497-504
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• 2020

A technique was developed for analysis on sonic boom created by supersonic flight and for prediction of its sound level and atmospheric propagation characteristics. It is of great importance to anticipate sound level of sonic boom because it causes environmental issue. For that purpose, the simplified sonic-boom prediction method was applied to calculate sound pressure according to physical properties and flight information of the object and distance to measurement site, in this study. Propagation characteristics of shock wave emanated from a flying object was analyzed by using line-of-sight vector and ray tracing method which dealt with refraction of wave due to atmospheric density distribution along altitude. Predicted results agreed well with measured data from real flight.