• International Journal of Air-Conditioning and Refrigeration
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• v.8 no.2
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• pp.89-100
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• 2000

Present study explains some experimental results on the aerodynamic noise of the cross-flow fan usually installed in the indoor unit of the room air-conditioners and provides a simple reduction method of radiating sound to decrease the total noise level. The spectra of the noise of the cross-flow fan were analyzed by the spectral decomposition method to characterize the generated sound. The unsteady fluctuating flow field was also measured using the I-type hot-wire probe. Comparing the spectral characteristics of the sound and the flow velocity, a useful noise reduction method was proposed, which bounds the region with a fence where the flow fluctuations were noticeably changed in the same fashion as the source spectral distribution functions vary. To validate the proposed method for reducing noise generated by the cross-flow fan, the sound pressure levels of the cross-flow fan system were compared with and without the bounding fence for various flow rates.

• Speech Sciences
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• v.11 no.4
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• pp.17-28
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• 2004

In this paper, we propose a statistical approach to improve the performance of spectral quantization of speech coders. The proposed techniques compensate for the distortion in a decoded line spectrum pairs (LSP) vector based on a statistical mapping function between a decoded LSP vector and its corresponding original LSP vector. We first develop two codebook-based probabilistic matching (CBPM) methods based on linear mapping functions according to different assumption of distribution of LSP vectors. In addition, we propose an iterative procedure for the two CBPMs. We apply the proposed techniques to a predictive vector quantizer used for the IS-641 speech coder. The experimental results show that the proposed techniques reduce average spectral distortion by around 0.064dB.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.871-879
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• 1999

Present study explains some experimental results on the aerodynamic noise of the cross-flow fan usually installed in the indoor unit of the room air-conditioners and provides a simple reduction method of radiating sound to decrease the total noise level. The spectrums of the noise of the cross-flow fan were analyzed by the spectral decomposition method to characterize the generated sound. The unsteady fluctuating flow field was also measured using the I-type hot-wire probe. Comparing the spectral characteristics of the sound and the flow velocity, a useful noise reduction method was proposed which bounds the region with a fence where the flow fluctuations were noticeably changed in the same fashion as the source spectral distribution functions vary. To validate the proposed method for reducing noise generated by the cross-flow fan, the sound pressure levels of the cross-flow fan system were compared of the experimental rig with and without the bounding fence for various flow rates.

• Journal of The Korean Astronomical Society
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• v.47 no.5
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• pp.195-199
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• 2014

We present a GUI-based interactive Python program, VIMAP, which generates radio spectral index maps of active galactic nuclei (AGN) from Very Long Baseline Interferometry (VLBI) maps obtained at different frequencies. VIMAP is a handy tool for the spectral analysis of synchrotron emission from AGN jets, specifically of spectral index distributions, turn-over frequencies, and core-shifts. In general, the required accurate image alignment is difficult to achieve because of a loss of absolute spatial coordinate information during VLBI data reduction (self-calibration) and/or intrinsic variations of source structure as function of frequency. These issues are overcome by VIMAP which in turn is based on the two-dimensional cross-correlation algorithm of Croke & Gabuzda (2008). In this paper, we briefly review the problem of aligning VLBI AGN maps, describe the workflow of VIMAP, and present an analysis of archival VLBI maps of the active nucleus 3C 120.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.6
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• pp.799-805
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• 1995

An infrared radiator of cordierite system were manufactured byslurry casting anddry pressing method. The characteristics of cordierite (2MgO.2Al$_{2}$O$_{3}$.5SiO$_{2}$)+30wt% clay+Xwt% MnO$_{2}$ of infrared radiator have been investigated as a function of MnO$_{2}$ additives (X=0, 0.1, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5). The thermal expansioncoefficient was decreased with increasing amounts of MnO$_{2}$ additives. Otherwise, the spectral emissivity was increased in the below 4.5.mu.m wavelength. Also, the infrared radiator of cordierite system which spectral emissivity was approximately 1.0 can be attainable at from 4.5.mu.m to 8.mu.m wavelength. The spectral emissivity was decreased from 8.mu.m to 14.mu.m above X=2.5.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.642-644
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• 2003

SAC is a compact electro-optical camera for imaging in visible-NIR spectral ranges. SAC provides highresolution images over the wide geometric and spectral ranges: 10 m ground sample distance (GSD) and 50 km swath width in the spectral ranges of 520 ${\sim}$ 890 nm. SAC is designed to produce high quality images: modulation transfer function (MTF) of more than 15 %; signal-to-noise ratio (SNR) of more than 100. The missions of SAC incorporate various imaging operations: multi-spectral imaging; super swath-width imaging with cameras in parallel; along-track stereo imaging with slanted 2 cameras.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06c
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• pp.133-137
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• 1994

In this paper, a method for designing an optimal weight function for the weighted cepstral distance measure is proposed. A conventional weight function or cepstral lifter is obtained eperimentally depending on the spectral components to be emphasized. The proposed method minimizes the error between word reference patterns and the traning data. To compare the proposed optimal weight function with conventional function, speech recognition systems based on Dpynamic Time Warping and Hidden Markov Models were constructed to conduct speaker independent isolated word necogination eperiment. Results show that the proposed method gives better performance than conventional weight functions.

• Korean Journal of Remote Sensing
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• v.30 no.3
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• pp.367-373
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• 2014

Albedo is one of the critical parameters for understanding global climate change and energy/water balance. In this study, we used red and NIR reflectance from Satellite Pour I'Obervation de la Terre (SPOT)/Vegetation (VGT) S1 product. The product is preprocessed for users that they are atmospherically corrected using Simple Method Atmospheric Correction (SMAC) by Vision on Technology (VITO) for calculating broadband albedo. Roujean's Bi-directional Reflectance Distribution Function (BRDF) model is a semi-empirical method used for BRDF angular integration and inversion. Each kernel of Roujean's model was multi integrated by angle components (i.e., viewing zenith, solar zenith, and relative azimuth angle). Black-sky hemispherical function is integrated by observational angle; whereas, white-sky hemispherical efficient is integrated by incident angle. Estimated spectral albedo of red ($0.61{\sim}0.68{\mu}m$, B2) and near infrared ($0.79{\sim}0.89{\mu}m$, B3) have a good agreement with MODIS albedo products.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.7
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• pp.1127-1140
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• 1997

With the study for identifying the transmission characteristics of vibration and noise generated by operating engine system of a vehicle, recently many engineers have studied actively the reduction of vibration and noise inducing uncomfortableness to the passenger. In this study, output noise was analyzed by multi-dimensional spectral analysis and vector synthesis method. The multi-dimensional analysis method is very effective in case of identification of primary source, but this method has little effect on suggestion for interior noised reduction. For compensation of this, vector synthesis method was used to obtain effective method for interior noise reduction, after identifying primary source for output noise. In this paper, partial coherence function of each input was calculated to know which input was most coherent to output noise, then with simulation of changes for input magnitude and phase by vector synthesis diagram, the trends of synthesized output vector was obtained. As a result, the change of synthesized output vector could be estimated.

• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.29-38
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• 1999

In this paper, the effects of superstrate on the radiation patterns of dipole on cylindrical bianisotropic subtrates were studied. Special constitutive relations are used to describe the bianisotropic properties of a material, such that the Green's function can be formulated. Electromagnetic fields and hounds conditions in spectral region were used to find Creen's function of the spectral representation and electromagnetic fields in space region were derived through inverse Fourier transformations of fields in spectral region using asymptotic formula for far zone. Radiation characteristics of axial Hertzian dipole on superstrate leaded cylindrical bianisotropic substrates were analyzed.