• Journal of Pharmaceutical Investigation
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• v.12 no.4
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• pp.132-144
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• 1982

The inclusion of ${\beta}-cyclodextrin$ $({\beta}-CyD)$ with prothionamide in aqueous phase was investigated by circular dichroism(CD), ultraviolet (UV) absorption, and solubility technique. The results suggested that a region of drug chromophore was located within the asymmetric center of ${\beta}-cyclodextrin$. Solubility and spectral changes were quantitatively treated to obtain stoichiometric ratio, which was found to be 1 : 1, and formation constants which were determined by solubility, CD, and UV method were 257, 367, and 389 $M^{-1}$, respectively. Also, the formation constant of the inclusion complex was determined by CD method at various pH. The result was that $K_c$ depended upon the pH of medium, and this fact also supported that thioamide moiety was accomodated in the cavity of ${\beta}-cyclodextrin$.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.209-210
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• 1998

Noise characteristics of preamplifier, the most essential part of on-chip signal processing circuitry for the active semiconductor neural probe, is the important factor determining the overall signal-to-noise-ratio (SNR). We present a systematic design method for the optimization of SNR, based on the spectral characteristics of the electrode, circuit noise and extracelluar action potential. Analytical expression is derived to calculate total output noise power. Output SNR of 2-stage CMOS preamplifier is tailored to meet the given specification while the layout area is minimized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.349-352
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• 2004

The $CdS_{1-x}Se_x$ thin films were grown on the GaAs(100) wafers by a Hot Wall Epitaxy method(HWE). The temperatures the source and the substrate temperature are $580^{\circ}C\;and\;440^{\circ}C$ respectively. The crystalline structure of thin films was investigated by double crystal X-tay diffraction(DCXD). Hall effect on the sample was measured by the van der Pauw method and studied on the carrier density and mobility dependence on temperature. In order to explore the applicability as a photoconductive cell, we measured the sensitivity($\gamma$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time.

• Current Optics and Photonics
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• v.5 no.3
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• pp.289-297
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• 2021

We describe a comb-mode resolving spectroscopic technique by direct time-domain phase correction of unstable interferograms obtained from loosely locked two femtosecond lasers. A low-cost continuous wave laser and conventional repetition rate stabilization method were exploited for locking carrier and envelope phase of interferograms, respectively. We intentionally set the servo control at low bandwidth, resulting in severe interferograms' fluctuation to demonstrate the capability of the proposed correction method. The envelope phase of each interferogram was estimated by a quadratic fit of carrier peaks to correct timing fluctuation of interferograms in the time domain. After envelope phase correction on individual interferograms, we successfully demonstrated 1 Hz linewidth of RF comb-mode over 200 GHz optical spectral-bandwidth with 10-times signal-to-noise ratio (SNR) enhancement compared to the spectrum without correction. Besides, the group delay difference between two femtosecond pulses is successfully estimated through a linear slope of phase information.

• Journal of the Korean Society of Radiology
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• v.8 no.5
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• pp.271-278
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• 2014

The purpose of this study is to know optimized fat suppression techniques for brachial plexus compared with STIR and SPAIR T1, T2 techniques. A total of 30 normal volunteers without brachial plexus disease were studied on a 3.0 T MRI scanner. As an analytical method, SNR, CNR, 4-point grading scale were evaluated by using three pulse sequences. As a quantitative analysis, the SNR, CNR for SPAIR T1 technique provided high value in branchial plexus roots (03.07, -2.25), branchial plexus trunks(06.70, 36.31)(p<0.05). As a qualitative Analysis, The visibility for delineation of brachial plexus, fat suppression, artifact was significantly better on SPAIR T1(3.2, 3.6, 3.4) technique(p<0.05).

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.3
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• pp.170-175
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• 2009

In this paper, we propose real time automatic speaker verification (ASV) system to protect personal information on personal digital assistant (PDA) device. Recently, the capacity of PDA has extended and been popular, especially for mobile environment such as mobile commerce (M-commerce). However, there still exist lots of difficulties for practical application of ASV utility to PDA device because it requires too much computational complexity. To solve this problem, we apply the method to relieve the computational burden by performing the preprocessing such as spectral subtraction and speech detection during the speech utterance. Also by applying the hidden Markov model (HMM) optimal state alignment and the sequential probability ratio test (SPRT), we can get much faster processing results. The whole system implementation is simple and compact enough to fit well with PDA device's limited memory and low CPU speed.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.30 no.1
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• pp.48-52
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• 2019

Background and Objectives : Functional aphonia is characterized by incomplete closure of the vocal folds. Semi-occluded vocal tract exercise (SOVTE) allows smoothly vocal folds collision without damage to the vocal folds tissues to produce normal vocal intensity. The purpose of this study is to report the effect of SOVTE in patients with functional aphonia. Materials and Method : Seven patients diagnosed with functional aphonia were treated with 1-3 voice therapy sessions using voiced lip-trill, humming, Lax Vox in SOVTE. To assess the effectiveness of semi-occluded vocal tract exercise, cepstral analysis and auditory perceptual assessment were performed before and after voice therapy. Results : F0 (fundamental frequency), CPP (cepstral peak prominence) and L/H ratio (low/high spectral ratio) were significantly increased, while CPP Standard deviation, L/H ratio Standard deviation were decreased. In addition, 'Grade', 'Breathiness' and 'Asthenia' were significantly decreased in the GRBAS scale after SOVTE (p<0.05). Conclusion : In our study, SOVTE seemed to be effective to elicit voice quickly and promote vocal folds vibration without muscular effort in patients with functional aphonia.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3A
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• pp.168-177
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• 2005

In this paper, we numerically investigated the optimum pump light power resulting best compensation of pulse distortion due to both chromatic dispersion and self phase modulation (SPM) in long-haul 3×40 Gbps wavelength division multiplexing (WDM) systems. We used mid-span spectral inversion (MSSI) method with path-averaged intensity approximation (PAIA) as compensation approach, which have highly nonlinear dispersion shifted fiber (HNL-DSF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that HNL-DSF is an useful nonlinear medium in OPC for wideband WDM transmission, and in order to achieve the excellent compensation the pump light power is selected to equal the conjugated light power into the latter half fiber section with the input light power of WDM channel depending on total transmission length. Also we confirmed that compensation degree of WDM channel with small conversion efficiency is improved by using pump light power increasing power conversion ratio upper than 1.

• The Journal of Engineering Geology
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• v.7 no.1
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• pp.63-79
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• 1997

In this study, our purpose is to develop a technique to discriminate artificial explosions from local microearthquakes on the basis of time-frequency domain. To obtain spectral features of artificial explosions and microearthquakes, we used 3-d spectrograms(frequency, time and amplitude) because this is a useful tool to study the frequency content of entire seismic waveforms observed at local and regional distances (e. g., Kim et al., 1994). P and S waves from quarry blasts show that frequency content of dominant amplitude appeared above 10 Hz and Rg phases that are observed at near distance ranges. But P and S waves from microearthquakes have more broad frequency content as well as below 10 Hz. And for discrimination, Pg/Lg spectral ratio is performed below 10 Hz. In order to select time windows we computed group velocity using multiple filter method(MFM) and removed free surface effects from all 3-components data for improving on data quality. Next step, we computed Fast-Fourier transform, and a log average spectral amplitude over seven frequency bands : 0.5 to 3, 2 to 4, 3 to 5, 4 to 6, 5 to 7, 6 to 8 and 8 to 10 Hz. The best separation is observed from 6 to 8 Hz.

• The Journal of the Korea Contents Association
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• v.9 no.1
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• pp.139-146
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• 2009

This paper addresses a modified spectral subtraction schemes which is suitable to speech recognition under low signal-to-noise ratio (SNR) noisy environment such as the automatic speech recognition (ASR) system in car. The conventional spectral subtraction schemes rely on the SNR such that attenuation is imposed on that part of the spectrum that appears to have low SNR, and accentuation is made on that part of high SNR. However, such postulation is adequate for high SNR environment, it is grossly inadequate for low SNR scenarios such as that of car environment. Proposed methods focused specifically to low SNR noisy environment by using weighting function for enhancing speech dominant region in speech spectrum. Experimental results by using voice commands for car show the superior performance of the proposed method over conventional methods.