• Journal of Biosystems Engineering
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• v.33 no.6
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• pp.404-409
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• 2008

Excessive presence of heavy metals in environment affects plants and fruits grown in the contaminated area. Rapid on-site monitoring of heavy metals can provide useful information for efficiently characterizing heavy metal-contaminated sites and for minimizing the exposure of the contaminated food crops to humans. This study reports on the evaluation of gold and glassy carbon (GC) electrodes with mercury or bismuth as a coating material for simultaneous determination of cadmium (Cd) and lead (Pb) in 0.1 M $HNO_3$ solution by anodic stripping voltammetry (ASV). The use of a square-wave voltammetric potential between a working electrode and a reference electrode caused Cd and Pb ions deposited on the electrode surface to be oxidized, thereby generating electric currents at different potentials. The mercury-coated gold electrode was not sensitive enough to detect the usable range of Cd concentrations (1 to 100 ppb). The GC electrodes with mercury or bismuth displayed well-defined, sharp and separate current peaks for Cd and Pb ions when the square-wave voltammetric potentials were applied. The peak currents measured with both mercury- and bismuth- coated GC electrodes were linearly proportional to Cd and Pb concentrations in the range of 1 to 200 ppb in 0.1 M $HNO_3$ with strong linear relationships between concentration and peak current ($R^2$ > 0.95), indicating that both of Cd and Pb ions could be quantitatively measured.

• Journal of Biomedical Engineering Research
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• v.29 no.2
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• pp.99-106
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• 2008

To improve $B_1$ homogeneity in high field MRI, the RF power is applied to the transmit array coil elements sequentially in the time-multiplexed way. Since only a single coil element is activated in a time-multiplexing slot, the global standing wave formation in the human body is greatly suppressed. The time-multiplexing slot width is on the order of micro seconds, hence, high-order-harmonic slices can be placed far from the transmit coil and simultaneous multiple slice selection can be avoided. The $B_1$ homogeneities of a birdcage coil and an eight-channel transmit array coil have been compared through finite difference time domain simulations. The simulation results indicate that the proposed technique can reduce the peak-to-peak $B_1$ inhomogeneity down to one fourth of the transmission with a birdcage coil on the central plane of the human head model at 3 T. The mimicking experiments at 3 T, eight separate experiments with a single coil element activated and image reconstruction by combining the eight images, also show promising results. It is expected that the proposed technique has some advantages over other $B_1$ improving methods in real practice since simple RF switching circuitries are only necessary and electromagnetic coupling between the coil elements is out of concern in its realization.

• Journal of Biosystems Engineering
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• v.33 no.1
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• pp.30-37
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• 2008

Dynamic excitation and response analysis is an acceptable method to determine some of physical properties of agricultural product for quality evaluation. There is a difference in the internal viscoelasticity between sound and defective fruits due to the difference of geometric structures, thereby showing different vibration characteristics. This study was carried out to develop a portable piezoelectric film-based glove sensor system that can separate internally damaged watermelons from sound ones using an acoustic impulse response technique. Two piezoelectric sensors based on polyvinylidene fluoride (PVDF) films to measure an impact force and vibration response were separately mounted on each glove. Various signal parameters including number of peaks, energy ratio, standard deviation of peak to peak distance, zero-crossing rate, and integral value of peaks were examined to develop a regression-estimated model. When using SMLR (Stepwise Multiple Linear Regression) analysis in SAS, three parameters, i.e., zeros value, number of peaks, and standard deviation of peaks were selected as usable factors with a coefficient of determination ($r^2$) of 0.92 and a standard error of calibration (SEC) of 0.15. In the validation tests using twenty watermelon samples (sound 9, defective 11), the developed model provided good capability showing a classification accuracy of 95%.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.4
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• pp.107-114
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• 2008

In this paper, we constructed a speech emotion recognition system that classifies four emotions - neutral, happy, sad, and anger from speech based on male/female gender discrimination. At first, the proposed system distinguish between male and female from a queried speech, then the system performance can be improved by using separate optimized feature vectors for each gender for the emotion classification. As a emotion feature vector, this paper adopts ZCPA(Zero Crossings with Peak Amplitudes) which is well known for its noise-robustic characteristic from the speech recognition area and the features are optimized using SFS method. For a pattern classification of emotion, k-NN and SVM classifiers are compared experimentally. From the computer simulation results, the proposed system was proven to be highly efficient for speech emotion classification about 85.3% regarding four emotion states. This might promise the use the proposed system in various applications such as call-center, humanoid robots, ubiquitous, and etc.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.5
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• pp.712-718
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• 2004

This study was carried out to separate the calcium-binding protein derived from enzymatic hydrolysates of cheese whey protein. CWPs (cheese whey protein) heated for 10 min at $100^{\circ}C$ were hydrolyzed by trypsin, papain W-40, protease S, neutrase 1.5 and pepsin, and then properties of hydrolysates, separation of calcium-binding protein and analysis of calcium-binding ability were investigated. The DH (degree of hydrolysis) and NPN (non protein nitrogen) of heated-CWP hydrolysates by commercial enzymes were higher in trypsin than those of other commercial enzymes. In the result of SDS-PAGE (sodium dodecyl sulphate polyacrylamide gel electrophoresis), $\beta$-LG and $\alpha$-LA in trypsin hydrolysates were almost eliminated and the molecular weight of peptides derived from trypsin hydrolysates were smaller than 7 kDa. In the RP-HPLC (reverse phase HPLC) analysis, $\alpha$-LA was mostly eliminated, but $\beta$-LG was not affected by heat treatment and the RP-HPLC patterns of trypsin hydrolysates were similar to those of SDS-PAGE. In ion exchange chromatography, trypsin hydrolysates were shown to peak from 0.25 M NaCl and 0.5 M NaCl, and calcium-binding ability is associated with the large peak, which was eluted at a 0.25 M NaCl gradient concentration. Based on the results of this experiment, heated-CWP hydrolysates by trypsin were shown to have calcium-binding ability.

• Archives of Pharmacal Research
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• v.23 no.2
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• pp.178-181
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• 2000

In order to study the simultaneous determination of (+)- and (-)-cetirizine in human urine we have developed a chiral separation method by HPLC. A chiral stationary phase of $\alpha$$_1$-acidglycoprotein, the AGP-CSP was used to separate the enantiomers. The pH of the phosphate buffer, as well as the content of the organic modifier in the mobile phase, markedly affected the chromatographic separation of (+)- and (-)-cetirizine. A mobile phase of 10 m㏖/1 phosphate buffer (pH 7.0)-acetonitrile (95 : 5, v/v) was used for the urine assays. Ultraviolet absorption was monitored at 230nm and roxatidine was employed as the internal standard for quantification. (+)-Cetirizine, (-)-cetirizine and the internal standard were eluted at retention times of 12, 16, and 32 mins, respectively. The detection limit for cetirizine enantiomers was 400 ng/$m\ell$ of urine. A pharmacokinetic study was conducted with the help of 5 healthy female volunteers who were administered with a single oral dose of racemic cetirizine (20 mg). The peak area ratios provided by the cetirizine enantiomers were linear(r>0.997) over a concentration range of 2.5-200 ${\mu}g/ml$. The peak of the excreted cetirizine enantiomers appeared in the urine sample during the period of 1-2 hrs following the administration of the oral dose. The excreted level of (+)-cetirizine was slightly higher than (-)-cetirizine but the difference was not statistically significant. However, this method appears to have applications for enantioselective pharmacokinetic studies of racemic drugs.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1497-1504
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• 2009

GC/MS analysis of catecholamines (CAs) in biological sample may produce poor reproducible quantitaion when chemical derivatization is used as the technique to form a volatile derivative. Significant quantities of the side products can be formed from CAs with primary amine during the derivatization reaction under un-optimized conditions. We have tested various chemical derivatization techniques in an attempt to find an optimum derivatization method that will reduce side product formation, enable to separate several catecholamine derivatives in GC chromatogram, and obtain significant improvement of detection sensitivity in GC/MS analysis. Whereas several derivatization techniques such as trimethylsilylation (TMS), trifluoroacylation (TFA), and two step derivatization methods were active, selective derivatization to form O-TMS, N-heptafluorobutylacyl (HFBA) derivative using N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA) and N-methyl-bis(heptafluorobutyramide) (MBHFBA) reagents was found to be the most effective method. Moreover, this derivative formed by selective derivatization could provide sufficient sensitivity and peak separation as well as produce higher mass ion as base peak to use selected ion in SIM mode. Calibration curves based on the use of an isotopically labeled internal standard show good linearity over the range assayed, 1 ~ 5000 ng/mL, with correlation coefficients of > 0.996. The detection limits of the method ranged from 0.2 to 5.0 ppb for the different CAs studied. The developed method will be applied to the analysis of various CAs in biological sample, combined with appropriate sample pretreatment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.6 s.360
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• pp.48-56
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• 2007

OFDMA (Orthogonal Frequency Division Multiple Access) is widely used as multiple access techniques for next generation mobile communication systems. However, OFDMA has a disadvantage of high peak-to-average power ratio and SC-FDMA (Single-Carrier Frequency Division Multiple Access) was proposed for uplink systems to overcome the drawback. SC-FDMA also has several demerits including degraded performance with high-order modulations or with multiple antenna techniques, and less flexibility in resource allocation and pilot patterns. In order to achieve the best performance over a wide range of environments, each mobile station should select either of OFDMA and SC-FDMA according to the given condition and a pilot structure for SC-FDMA systems should be similar to that of OFDMA to maintain the same frame structure. While conventional SC-FDMA schemes require an entire SC-FDMA symbol or a separate short symbol for pilots, this paper proposes a method which supports the pilots included in SC-FDMA data parts and enables a SC-FDMA frame to hold the same structure as an OFDMA frame.

• Journal of Yeungnam Medical Science
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• v.11 no.1
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• pp.101-108
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• 1994

Many previously described nuclear medicine procedures to assess glomerular filtration rate have some problems because numerous blood sample is to be taken and they don't measure each separate renal function. Gates described isotopic method for the measurement of global and unilateral GFR based on the fractional renal uptake of $^{99m}Tc$-DTPA 2 to 3 minutes after its intravenous injection. We evaluated GFR using $^{99m}Tc$-DTPA in 57 people according to Gates method and compared with creatinine clearance. A good correlation was observed between creatinine clearance and GFR calculated by Gates' formula with an r value of 0.9(P<0.05). And also the relationship between parameters of $^{99m}Tc$-DTPA renal scan images and GFR was taken. They were significantly correlated with GFR calculated by Gates' formula : r value 0.66 between relative intensity of peak renal to peak aortic activity(pK/pA) and GFR, -0.42 between time between aortic and kidney peak(A-K) and GFR and -0.48 between parenchymal renal activity at 25 min compared to peak kidney activity(25K/pK) and GFR. In conclusion, the determination of GFR according to the Gates' formula shows good and reproducible of GFR with rapidity and simplicity. And the parameters from the renal scan images can use to estimate the renal function.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.296-302
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• 2013

The binary offset carrier (BOC) modulation has attracted much attention as a new physical layer implementation for satellite communication and global navigation satellite systems. In this paper, we propose a new correlation function for sine-phased BOC signals. Specifically, we separate a sub-carrier pulse into several rectangular pulses, and then, generate a number of partial correlation functions. Finally we combine the partial correlation functions to yield an unambiguous correlation function with no side-peak. From numerical results, it is demonstrated that the proposed correlation function provides a significant tracking performance improvement over the conventional correlation functions.