• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.411-414
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• 1999

Insertion loss of partially Inclined noise harrier Is studied by using multiple diffraction theory. The diffractions occurred at the top as well as partially folded point are included based on Kouyoumjian and Pathak's method (Procd. IEEE, Vol. 62, 1974). Scaled-down model of noise barrier is studied in anechoic rooom. It is shown that the theoretical results generally represents the average values of experimental results, while there are many oscillations in experimental results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.3
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• pp.6-11
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• 1977

The noise behavior of the Schottky Barrier Gate FET has been investigated by the use of noise equivalent circuit. It has been found that an additional noise source has to be taken into account in the GaAs SBGFET's biased in the pinch-off region; the intervalley scattering noise and the hot electron noise. In this paper, a noise equivalent circuit has been used to determine the noise parameter which was taken into account influence of the saturation velocity of carrier and parasitic resistance.

• Journal of Environmental Impact Assessment
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• v.23 no.2
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• pp.112-118
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• 2014

The application of a 3-d noise prediction model is increasing as a tool for performing actual noise assessment in order to investigate the noise impact of the residential facility around a development region. However, because the appropriate plans of applying a 3-d noise prediction model is insufficient, it is important to secure the reliability of the noise prediction results generated by a 3-d noise prediction model. Therefore, this study is focused on examining a 3-d noise prediction model, and a prediction equation and input data in it. For this, the 3-d noise prediction models such as SoundPLAN, Cadna-A, IMMI is applied in road noise. After the contents of road noise equations, input data of road noise source, and input data of road noise barrier are understood, the road noise prediction results are compared and examined according to the variation of 3-d noise prediction model, road noise equation, and input data of road noise source and road noise barrier.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.5
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• pp.627-634
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• 2018

In the study, computational fluid dynamics analysis was performed to estimate wind force coefficients for a box-type concrete girder bridge under the influence of wind. The drag, lift and pitching moment coefficients were obtained for the bridge section without noise barrier and compared with those of the bridge section with noise barriers of various heights. The shear stress transport $k-{\omega}$ turbulence model was employed to estimate the wind force coefficients, and the contribution of the friction drag force to the total drag force was investigated. It was found from the study that the drag force coefficients increased as the height of noise barrier increased when a wind blew horizontally, and that the contribution of the friction drag force was highest for the bridge section without noise barrier. It is concluded that the impact of the height of noise barriers should be considered in the design of bridges, and the friction force played an important role in evaluating wind forces on bridges.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.535-541
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• 2004

For housing estate of a new administrative capital city, Noise reduction method is a important design factor. As measuring a noise level of traffic noise according to separation from road, it can be created a quite housing estate. Analyzing of merits and demerits in sound barrier walls and tunnels can be proposed environment friendly soundproofing facilities. Number of measurement was performed to know what kind of layout of housing estate is good for noise reduction. Through this measurement, ㄷ shaped layout or parallel layout has the advantage of sound insulation rather than right angled layout. In this case (ㄷ shaped layout or parallel layout) buildings neighboring to the road should be designed to insulate sound. Evergreen trees should be planted between housing estate and road more than 30m (at least 7～8m) in order to reduce noise and have masking effects. If broad-leaved trees are planted more than 30m, approximately 10dB noise is reduced and 2～4dB if 7～8m. Roads in the estate should be designed considering pedestrians first, and special roads for moving and ambulance should be designed as skew road, if possible. The result shows that 15$^{\circ}$-sloped‘S’road reduces 1～2dB noise and 30$^{\circ}$-sloped road reduces 4～7dB. If noise barrier is inevitably installed, it should be designed to go well wit neighboring environment so as to install Environment Friendly Noise Barrier using materials and trees including wood and soil. Through this study the results are used to guideline for construction of environment friendly housing estate

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2368-2373
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• 2011

Traffic noise annoyance in dwelling area like private houses and apartment is becoming very important issue nowadays in South Korea. In this paper frequency analysis of the traffic noise was performed. Based on sound pressure levels analyses and its frequency content specific requirements for component of active noise control systems are formulated. Active compensational loudspeaker, microphone front end and DSP design were analysed, considered and proposed. Components specifications and design solutions are verified using modelling and experimental technique.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.757-761
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• 2001

In order to study noise barriers of complex shapes and to assess their efficiency, precise prediction model is required. For instance, geometrical approaches cannot deal with complex diffraction effects. So that in this paper, the time domain numerical computation method(Computational Aeroacoustics method) is applied to estimate noise reduction by diffraction and finite impedance condition. The CAA method can be used to calculate exactly the pressure of complex barrier shape with different impedance condition, such as T-shape, cylindrical edge and multi-edge noise barriers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1778-1783
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• 2000

When visual intrusion is an important factor, it is desirable to find alternative methods of improving the insertion loss of a noise barrier without increasing the height. Therefore, the primary object of the work attenuates the noise due to transport vehicle by small interference device installed at noise barrier edge. In this paper the performance of noise barriers with attached interference device, in terms of shape, absorptive material and split panel, are examined using the boundary element approach. Also, the scale models are moanted in an anechoic chamber and the frequency of the sound sources are appropriately scaled to simulate full scale site conditions. Lastly, experimental measurements of the designs are executed for a range of frequencies and receiver positions, and are compared with the results of numerical modeling.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.791-796
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• 2010

Installing noise barriers is the most common method for reducing the highway traffic noise to the road side residential area. After the report about edge potential concept of a noise barrier, various types of noise reducing devices(NRDs) called "noise reducers" have been suggested for getting more shielding effect on the top of highway noise barriers. But, it has been doubtful about effect of the NRDs in field because there was no appropriate and unified method to estimate the acoustic performance by using field measurement of the NRDs in Korea. In this study, the authors have considered to setup a practical method to test and estimate the acoustic performance of NRDs. For eliminating the noise reduction effect of the NRDs height itself, the source and measuring points are adjusted as highly as the NRDs height. For the frequency weighting in the estimation of the NRDs effect, the highway noise spectra were measured at asphalt and concrete road side and then averaged for a unit spectral parameter.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1099-1105
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• 2012

Transparent noise barrier panels have the advantages of transmitting light to nearby residents and allowing drivers to orientate themselves by providing views of the surrounding area. To develop guidelines on quality criteria for transparent soundproof panels, their sound transmission loss and weatherability were experimentally investigated. In Korea, the sound transmission loss of noise barrier panels should be more than 25 dB at 500 Hz and 30 dB at 1000 Hz. The transmission loss tests of transparent panels were performed in accordance with KS F 2808. Typically, plastic materials suffer from color changes when exposed to ultraviolet(UV) light over extended periods. Therefore, weathering of plastics is one of the most important properties for outdoor applications. Protection against UV radiation and weathering is usually accomplished by using UV stabilizer additives or coatings. Transparent materials for soundproof panels were examined through accelerated weathering tests and their weathering resistances were evaluated from changes in yellowness index.