• Journal of Korea Multimedia Society
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• v.18 no.4
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• pp.437-442
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• 2015

Voice activity detection is very important process that voice activity separated form noisy speech signal for speech enhance. Over the past few years, many studies have been made on voice activity detection, but it has poor performance in low signal to noise ratio environment or fickle noise such as car noise. In this paper, it proposed new voice activity detection algorithm using ensemble variance based on wavelet band entropy and soft thresholding method. We conduct a survey in a lot of signal to noise ratio environment of car noise to evaluate performance of the proposed algorithm and confirmed performance of the proposed algorithm.

• Journal of the Korean Society for Nondestructive Testing
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• v.6 no.2
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• pp.46-56
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• 1987

The effect of ultrasonic search units on the detectability and size evaluation of planar flaws was studied for thicker ferritic material using the technique of the DAC curve and reference level. Cylindrical holes were used as calibration reflectors. The planar flaws such as disc and band types were machined. They were detected and evaluated with different search units and sizing criteria. The value evaluated was compared with the actual dimension of planar flaws.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1386-1396
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• 2017

In this paper, a new approach is proposed to select the optimal sitting and sizing of distributed solar photovoltaic generation (SPVG) in a radial electrical distribution systems (EDS) considering load/generation uncertainties. Here, distributed generations (DGs) allocation problem is modeled as optimization problem with network loss based objective function under various equality and inequality constrains in an uncertain environment. A boundary power flow is utilized to address the uncertainties in load/generation forecasts. This approach facilitates the consideration of random uncertainties in forecast having no statistical history. Uncertain solar irradiance is modeled by beta distribution function (BDF). The resulted optimization problem is solved by a new Dynamic Harmony Search Algorithm (DHSA). Dynamic band width (DBW) based DHSA is proposed to enhance the search space and dynamically adjust the exploitation near the optimal solution. Proposed approach is demonstrated for two standard IEEE radial distribution systems under different scenarios.

• Publications of The Korean Astronomical Society
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• v.10 no.1
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• pp.127-134
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• 1995

Recent discovery of an Io-related feature in Jupiter's auroral regions prompted us to search for an or multiplet at $1304{\AA}$ in IUE aurora spectra. In three independent IUE spectra taken on January 18, 1981, we found an emission structure at $1304{\AA}$, with a signal-to-noise of about three. If the structure is due to the OI emission, then it is a direct evidence of oxygen ion precipitation, which may originate from Io and Io torus. The emission rates of the $H_2$ band systems and the or multiplet are about 50 kR and 150 R, respectively. We have constructed high resolution model spectra with the estimated emission rates of $H_2$, OI and SI for the Goddard High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope. The model spectra clearly show the or and SI mulitplets separated from crowded $H_2$ Lyman and Werner band lines, and therefore it is promising to detect the OI and SI multiplets with the GHRS. Given the possibility that the lo-related feature may be caused by ion precipitations from the Io flux tube, it is likely that the OI emission may be detected in the footprint area of the IO flux tube.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1133-1143
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• 2005

In this paper, we propose an enhanced two-step search scheme for rapid and reliable signal acquisition in UWB systems under multipath channels. The proposed TSS-LS (Two-Step Search scheme with the Linear search based Second step) achieves rapid acquisition performance comparable to the conventional TSS-BS (Two-Step Search scheme with the Bit reversal search based Second step) already proposed by the authors, based on the single-dwell search with two-step thresholds and search windows. However, unlike the TSS-BS which employs the bit reversal search in the second step, the proposed TSS-LS utilizes the linear search in the second step to improve the reliability of signal acquisition. Simulation results with multipath channel models by IEEE 802.15.3a show that the two-step search schemes for the UWB signal acquisition can achieve sig nificant reduction of the required mean acquisition time as compared to general search schemes. In addition, we observe that the proposed TSS-LS achieves quite good bit error rate performance for large signal-to-noise ratios, which is favorably comparable to the case of ideal perfect timing.

• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.33-36
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• 2001

With all the researches to define human genom and to look for some new bio-activated material in the bio-technology field recently, it is more highly needed to analyse DNA or so called Material than ever before. First, the lanes are extracted based on histogram analysis and projection technique. And then three other approaches are applied for band extraction: SB, RG-1, and RG-2. In SB method, a search line is set dividing each lane equally and vertically to find peaks and valleys. And according to them, minimum enclosing rectangle of each band is determined. In RC-1 approach, on the other hand, band areas are extracted by region growing with the peaks as seeds, avoiding the overlap with the neighboring bands. In RC-2 approach, peaks and valleys are searched in two lines that trisect the lane vertically, and the pair of peaks in the same band are determined, and then used to grow the region. To compare the accuracy of the three suggested methods, we measure the location and amount of bands. The result shows that the mean deviation of the location is 0.06, 0.03, and 0.01 for SB, RG-1, and RC-2 respectively. And the mean deviation of the amount of bands is 0.08, 0.05, and 0.02 for SB, RG-1, and RG-2 respectively. In conclusion, the RG-2 method suggested in this paper appears to be the most reliable on the degree of the accuracy in measuring the location and amount of bands

• The Journal of the Acoustical Society of Korea
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• v.14 no.1E
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• pp.46-55
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• 1995

In this paper, we present a new wavelet transform-based CELP coder, called band selection wavelet transform CELP (BS-WTCELP) operated at 4.8 kbps. The proposed algorithm uses a band selection scheme of frequency bands of wavelet transform and selective vector quantization (VQ). The band selection and selective VQ structure is implemented by using a classified VQ structure. The proposed algorithm has about 0.5-1.0 dB improvement in segmental SNR compared with the conventional CELP that uses the random codebook search, while is has significantly reduced computational and storage complexity. Many experimental results have shown that the proposed algorithm is more suitable for most real-applications than the conventional CELP and wavelet transform CELP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.359-365
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• 1998

The portable two way radio telephone amongst GMDSS equipment in the vessel is very important portable wireless one for search and rescue in distress situation. Although the portable two way radio telephone must be equipped with in the vessel by IMO & RR, other kinds of wireless tranceivers are widely used to communicate with crew members who are separately appointed at bridge forecastle and poop in leaving or arriving at the port, passing through a narrow canal or voyaging in the foggy weather, Most of those wireless tranceivers except portable two way radio telephone are allocated at 27MHz band with PTT simplex system that makes crew members difficult to work effectively in the vessel. In this research 900MHz band FDD(frequency duplex division) tranceiver system is studied to help crew members in the vessel to communicate with themselves freely and to work easily meanwhile with simple operation. 900MHz band FDD tranceiver system uses one chip FM frontend IC to realize the miniaturization and downsizing of tranceiver and small size head set attached to helmet. The credibility of this research's result is highly evaluated by circuit analysis with computer aided simulation, and partly modified 900MHz band cordless phone circuit.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.365-370
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• 1998

The portable two way radio telephone amongst GMDSS equipment in the vessel is very important portable wireless one for search and rescue in distress situation. Although the portable two way radio telephone must be equipped with in the vessel by IMO RR, other kinds of wireless tranceivers are widely used to communicate with crew members who are separately appointed at bridge forecastle and poop in leaving or arriving at the port, passing through a narrow canal or voyaging in the foggy weather. Most of those wireless tranceivers except portable two way radio telephone are allocated at 27MHz band with PTT simplex system that makes crew members difficult to work effectively in the vessel. In this research 900MHz band FDD(frequency duplex division) tranceiver system is studied to help crew members in the vessel to communicate with themselves freely and to work easily meanwhile with simple operation. 900MHz band FDD tranceiver system uses one chip FM frontend IC to realize the miniaturization and downsizing of tranceiver and small size head set attached to helmet. The credibility of this research's result is highly evaluated by circuit analysis with computer aided simulation. and partly modified 900MHz band cordless phone circuit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.362-370
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• 2011

This paper presents a K-band radar system installed on the ground moving vehicle to detect and track a high-speed target. The presented radar is separated into three search regions to satisfy a wide area detection and a limitation of the installing space of the radar, and each region performs detecting the target independently and tracking the detected target automatically. The presented radar radiating K-band FMCW waveform acquires range and velocity information of the target at the every dwell and receiving antenna of the radar is applied the multiple baseline interferometer to extract the precise angle information of the target. 3-dimensional tracking accuracy of the radar is 0.25 m RMSE measured actually through a fire experiment of an imitation target.