• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.386-391
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• 2006

In this paper, a design of V-type Linearly Tapered Slot Antenna(V-LTSA) with uniplanar microstrip-to-coplanar stripline(CPS) transitions is presented. The effect of reducing and increasing with taper width G, teper length L and opening angle are also considered at 5.8 GHz. In the result of a simulation by using CST-MWS, the return loss characteristic came very wide band about 4.3GHz, or 1.8 Octave. Proposed V-LTSA design schemes are expected to be a good antenna for microwave and millimeter-wave communcations.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.201-206
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• 2012

PURPOSES: This study evaluated a measuring technique for tire-pavement interaction noise that uses a noble close proximity (NCPX) method as well as for noise level measured inside of a car (e.g., Inside Noise Level) in term of rumble strips constructed at a tall gate. METHODS: According to the measurements of NCPX and inside noise level (INL), 1/3 octave band frequency analysis and overall noise level calculation were conducted in order to evaluate noise levels of NCPX and INL, depending on types of rumble strips. RESULTS: The tested sections of general concrete pavement surface and two different types of rumble strips were evaluated, using 1/3 octave band frequency analysis and overall noise level. From the analyzed results, it can be concluded that rumble strips generate a relatively huge noise levels when compared to the concrete pavement surface. CONCLUSIONS: Noting that above 3 dBA different noise levels can let drivers know that they are getting close to toll gate; therefore, they should apply their brakes. Thus, the noise levels of rumble strips are required to be reduced, based on considering the neighbors living near toll gates.

• International Journal of Highway Engineering
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• v.15 no.6
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• pp.61-68
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• 2013

PURPOSES : The purpose of this study is to study the noise reducing effect of Micro Surfacing by comparing general asphalt, longitudinal tining and Slurry Seal. METHODS : This study measures vehicles' noise of each section by the NCPX method that can measure noise between the road surface and the tire at the field. Total sound pressure and sound pressure level by the 1/3 octave band frequency are calculated through the field data of each section. Total sound pressure level is compared by ANOVA test statistically. After ANOVA test, post-hoc test is conducted to know mean difference of surface type by Tukey. RESULTS : As the result of CPB analysis to confirm sound pressure levels by frequency, it was shown that sound pressure levels by frequency are totally similar except for those of frequency bands between 100Hz and 500Hz. The result of ANOVA test and post-hoc test, it was shown that sections of surface type have a difference. The result of Micro Surfacing was lower 2~5dB(A) than other surface type. CONCLUSIONS : It is found that the noise reduction performance of Micro Surfacing was better than other surface type.

• International Journal of Railway
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• v.2 no.4
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• pp.152-163
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• 2009

In this paper, the correlation between the accelerations measured at the track components and the parameters affecting the acceleration is analyzed. To do it, the accelerations of each track component such as rails, sleepers and ballast are measured in Kyong-Bu high-speed Line. The RMS values of the measured accelerations are calculated and the pad stiffness, the longitudinal irregularity, running velocity and the corrugation, are considered as the parameters affecting the acceleration. By using the linear regression, the correlation coefficients are calculated to analyze the relationship between the acceleration characteristics and the parameters. Also, the 1/3 Octave analysis is calculated to analyze the dominant frequency band of the accelerations of the track components.

• The Journal of the Acoustical Society of Korea
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• v.1 no.1
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• pp.76-81
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• 1982

To get minimum noise level by making full use of the constrained geometric space and being compatible with the minimum pressure-drop condition, 3-pipe through-flow system is designed by inserting a new pipe which is shaped a resonator in the cavity of 2-pipe system. As a result of the 1/3-octave-band frequency analysis for the noise reduction characteristics, this system is proved to have good sound attenuation effect in the high frequency region, so that it is found to be a useful component of a muffler.

• The Journal of the Acoustical Society of Korea
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• v.20 no.3
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• pp.98-103
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• 2001

The binaural auditory system of human has the capability of differentiating the direction and distance of sound sources. This feature is well characterised in terms of the inter-aural intensity difference (IID), the inter-aural time difference (ITD) and/or the spectral shape difference (SSD) arising from the acoustic transfer of a sound source to the outer ears. This paper proposes an effective way of extracting the three sound perception factors (IID, ITD, SSD) from the head-related transfer functions (HRTF's) that depends on the direction and distance of the acoustic source from the listener. It includes the estimation method of the equivalent ITD and 1/3-octave band-based IID factors and their usage to locate a sound source in space. Subjective and objective tests were carried out to examine the effectiveness of the proposed methodology and its applicability to real sound systems. Those experimental results are illustrated in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.185-190
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• 2000

The sound absorption coefficient of glass wool (bulk density of 48 kg/$m^3$ and 32 kg/$m^3$) was measured by reverberation room method as varying their cross-sectional area. The results show that the absorption is larger for smaller samples because of edge effect. The absorption coefficient with two different kinds of sources, 1/3-octave band and white noise, gives similar values.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.463-472
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• 2007

In this paper, the correlation between the vibration characteristics of the track components and the parameters affecting the vibration is analysed. To do it, the accelerations of each track component such as rails, sleepers and ballast are measured in Kyong-Bu high-speed line. The RMS values of the measured data are calculated and the pad stiffness, the longitudinal irregularity, running velocity and the corrugation, are considered as the parameters in the viewpoint of track. By using the linear regression, the correlation coefficient is calculated to analyse the relationship. Also, the 1/3 Octave analysis is calculated to analyse the dominant frequency band of tile vibrations of the track components.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.95-105
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• 2013

PURPOSES: The purpose of this study is to research the influence of road traffic noise by road slope through the analysis of the field road traffic noise and determine consideration of road slope in the case of appling active noise cancellation. METHODS: This study measures vehicle's noise by the NCPX method at the three field sections such as uphill, downhill, and flatland. Total sound pressure and sound pressure level by the 1/3 octave band frequency are calculated through the raw field data. Total sound pressure level is compared by ANOVA test and T test statistically. The results obtained are compared in accordance with the road slope and the progress of the uphill section. RESULTS : The noise characteristic of early, medium, and last parts of uphill was found to be consistent when the vehicle was travelling uphill section. The result of statistical test, it was shown that total sound pressures are not different each other. According to the comparison by the geometry, sound pressure of the uphill section was higher than those of the flatland and downhill section in high frequency band. By the result of statistical test, total sound pressure are different according to geometry in the case of high vehicle speed. In the comparison result by road slope, each sound pressure level was found to be consistent in total frequency. However, total sound pressure proportionally increased according to road slope. CONCLUSIONS: It is found that the effect of road slope on noise generation was little in this experimental sites.

• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.6
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• pp.23-29
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• 1981

By using a slot-line in combination with microstrip lines, a coplanar wide-band balun is designed and fabricated. The slot-line of balun junction is compensated to be operated in C-band(4~8GHz), and therefore the results are agreement with theoritical prediction. Experimental data are given for a 3-section Chebyshev transformer-matched balun with a balanced-to-unbalanced line impedance ratio of 2 : 1. A bandwidth from 3.5GHz to 7.0GHz is obtained with V.S.W.R. of below 1.2 : 1. Maximum insertion loss is measured as 0.9dB, and the phase difference varies linearlly within 180$^{\circ}$$\pm$5$^{\circ}$.