• Journal of Navigation and Port Research
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• v.29 no.1 s.97
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• pp.23-28
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• 2005

The signal in wireless multi-path channel is affected by fading and ISI because of high data rate transmission, so the signal has the high error rate. The present modulation and demodulation method of DSRC system can not expect sufficient for providing data service over 1 Mbps, so the channel equalization and advanced modulation and demodulation methods are required. OFDM is generally known as an effective technique for high data rate transmission system, since it can prevent ISI by inserting a guard interval. However, a guard interval longer than channel delay spread has to be used in each OFDM symbol period, thus resulting a considerable loss in the efficiency of channel utilization Therefore the equalizer is necessary to cancel ISI to accommodate advanced ITS service with higher bit rate and longer channel delay spread condition In this paper, the channel equalizer for the OFDM -DSRC system was designed and its performance in a multi-path fading environment was evaluated with computer simulation.

• Analytical Science and Technology
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• v.8 no.1
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• pp.17-23
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• 1995

The determination method of 2-mercapto-1-methyl-imidazole(MMI) in $5.0{\times}10^{-2}M$ lithium perchlorate solution has been investigated by the differential pulse polarography. The optimum conditions for the determination of MMI were as fellows; -0.9 volt(vs. Ag/AgCl) initial potential, 80mV pulse height, 2mV/sec scan rate, and medium mercury drop size. The calibration curve showed a good linearlity in the range of $1.0{\times}10^{-7}M$ to $8.0{\times}10^{-5}M$ and the detection limit was $2.2{\times}10^{-9}M$. This method was applicable to the determination of MMI in thyroid drugs without interference from the additives.

• Journal of Korean Foot and Ankle Society
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• v.13 no.1
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• pp.23-27
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• 2009

Purpose: The purpose of this study was to evaluate the clinical outcome of neglected Achilles tendon rupture treated with reconstruction and augmentation with flexor hallucis longus (FHL) tendon using one incision technique. Materials and Methods: Between July 2006 and March 2008, eleven patients with neglected Achilles tendon rupture received surgical treatment. Through one incision technique, augmentation with auto FHL tendon transfer was performed using a Bio-Interference screw (Arthrex, Naples, FL) and followed by V-Y advancement (5 cases) or gastronemius fascial turn-down flap procedure (6 cases). After mean follow up of 20.7 months (range, 11.8-33.3 weeks), clinical outcomes were evaluated with Visual Analogue Scale (VAS), American Orthopedic Foot and Ankle Society (AOFAS) score, 10 repetitive double heel raise test, 10 repetitive single heel raise test and subjective satisfaction. Results: The length of the gap after debridement was $5.4{\pm}2.0$ cm. The VAS improved from $4.1{\pm}0.9$ to $1.5{\pm}0.8$ at last follow up (p<0.05). The AOFAS score increased from $38.9{\pm}12.2$ to $91.5{\pm}8.9$ at last follow up (p<0.05). Eight patients were satisfied with excellent results and three were satisfied with good results. All patients were able to perform 10 repetitive double heel raise and nine out of eleven patients were able to perform 10 repetitive single heel raise at last follow up. There were no complications including deep infection or re-rupture. Conclusion: Augmentation with FHL tendon transfer and reconstruction with V-Y advancement or turn-down flap through one incision technique appeared to be effective and safe. This technique is recommendable for the treatment of neglected Achilles tendon rupture.

• Korean Journal of Food Science and Technology
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• v.22 no.7
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• pp.802-804
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• 1990

A new colorimetric method to analyze ${\alpha}-Cyclodextrin({\alpha}-CD)$ by using a property of ${\alpha}-CD$ to decolor the starch-iodine complex, was presented. ${\alpha}-CD$ was quantitatively determined as follows. The ${\alpha}-CD$ standard solutions at concentrations up to 2 mg/ml were prepared. To 1ml of starch-iodine complex solution which contained starch(1%) and iodine (0.02% $I_2$, 0.2% KI) equivalently in distilled water, $200\;{\mu}l$ of ${\alpha}-CD$ standard solutions and 3 ml of distilled water were added and the absorbance was measured at 570 nm. Using this mothod ${\alpha}-CD$ concentration range at $0{\sim}2\;mg/ml$ could be determined and their absorbance patterns at 570 nm showed a good linearity. ${\beta}(CD)$ and glucose had no interference in this method for ${\alpha}-CD$ determination.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.177-182
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• 2007

This paper presents the InGaP/GaAs HBT differential LC VCO with low phase noise performance for adaptive feedback interference cancellation system(AF-lCS). The VCO is verified with enhanced tank structure including filtering technique. The output tuning range for proposed VCO using asymmetric inductor and symmetric capacitors withlow pass filtering technique is 207 MHz. The output powers are -6.68 including balun and cable loss. The phase noise of this VCO at 10 kHz, 100 kHz and 1 MHz are -102.02 dBc/Hz, -112.04 dBc/Hz and -130.40 dBc/Hz. The VCO is designed within total size of $0.9{\times}0.9mm^2$.

• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.411-417
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• 1994

For the analysis of fine ceramics, which is one of the new materials difficult to be dissolved, the methods of sample pretreatments such as alkali fusion and high pressure acid digestion were studied using inductively coupled plasma-atomic emission spectrometer(ICP-AES). For the Al2O3 powder sample, the results from high pressure acid digestion method showed better reproducibility than those obtained by alkali fusion technique. In the case of the analysis of SiC powder using the former method, impurities of the powder in the range of ppm were determined without matrix interference by removing Si as Si-F volatilization. Japan Certified Reference Materials (JCRM022 and JCRM023) were analyzed by this method for ultra fine powder and the results showed high accuracy and good reproducibility.

• Journal of Magnetics
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• v.19 no.2
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• pp.126-129
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• 2014

We report the crystallographic and magnetic properties of $Ni_{0.3}Fe_{0.7}Ga_2S_4$ by means of X-ray diffractometer (XRD), a superconducting quantum interference device (SQUID) magnetometer, and a M$\ddot{o}$ssbauer spectroscopy. In particular, $Ni_{0.3}Fe_{0.7}Ga_2S_4$ was studied by M$\ddot{o}$ssbauer analysis for evidence of spin reorientation. The chalcogenide material $Ni_{0.3}Fe_{0.7}Ga_2S_4$ was fabricated by a direct reaction method. XRD analysis confirmed that $Ni_{0.3}Fe_{0.7}Ga_2S_4$ has a 2-dimension (2-D) triangular lattice structure, with space group P-3m1. The M$\ddot{o}$ssbauer spectra of $Ni_{0.3}Fe_{0.7}Ga_2S_4$ at spectra at various temperatures from 4.2 to 300 K showed that the spectrum at 4.2 K has a severely distorted 8-line shape, as spin liquid. Electric quadrupole splitting, $E_Q$ has anomalous two-points of temperature dependence of $E_Q$ curve as freezing temperature, $T_f=11K$, and N$\acute{e}$el temperature, $T_N=26K$. This suggests that there appears to be a slowly-fluctuating "spin gel" state between $T_f$ and $T_N$, caused by non-paramagnetic spin state below $T_N$. This comes from charge re-distribution due to spin-orientation above $T_f$, and $T_N$, due to the changing $E_Q$ at various temperatures. Isomer shift value ($0.7mm/s{\leq}{\delta}{\leq}0.9mm/s$) shows that the charge states are ferrous ($Fe^{2+}$), for all temperature range. The Debye temperature for the octahedral site was found to be ${\Theta}_D=260K$.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1375-1382
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• 2007

A column preconcentration method with pulverized Amberlite XAD-4 loaded with bismuthiol I (BI) has been developed for the determination of trace Cd(II) and Cu(II) in various real samples by flame atomic absorption spectrophotometry. Various experimental conditions, such as the size of XAD-4, adsorption flow rate, amount of bismuthiol I, stirring time for adsorbing bismuthiol I on XAD-4, pH of sample solution, amount of XAD-4- BI, desorption solvent, and desorption flow rate, were optimized. Also, the adsorption capacity and the adsorption rate of Cd(II) and Cu(II) on XAD-4-BI were investigated. The interfering effects of various concomitant ions were investigated, Bi(III), Sn(II) and Fe(III) were found to affect the determination. But the interference by these ions was completely eliminated by adjusting the amount of XAD-4-BI resin to 0.70 g, although the adsorption flow rate was slower. For Cd(II) our proposed technique obtained a dynamic range of 0.5-40 ng mL-1, a correlation coefficient (R2) of 0.9913, and a detection limit of 0.3 ng mL-1. For Cu(II), the corresponding values were 2.0-120 ng mL-1, 0.9921 and 1.02 ng mL-1. To validate this proposed technique, the aqueous samples (stream water, reservoir water, tap water and wastewater), the diluted brass sample and the plastic sample, as real samples, were used. Recovery yields of 91-103% were obtained. These measured data were not different from ICP-MS data at 95% confidence level. Our proposed method was also validated using rice flour CRM (normal, fortified) samples. From the results of our experiment, we found that the technique we present here can be applied to the determination of Cd(II) and Cu(II) in various real samples.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1
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• pp.46-53
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• 1996

Adaptive LMS algorithm has been used in many application areas due to its low complexity. In this paper input signal is transformed into the subbands with arbitrary bandwidth. In each subbands the dynamic range can be reduced, so that the independent filtering in each subbands has faster convergence rate than the full band system. The DCT transform domain LMS adaptive filtering has the whitening effect of input signal at each bands. This leads the convergence rate to very high speed owing to the decrease of eigen value spread Finally, the filtered signals in each subbands are synthesized for the output signal to have full frequency components. In this procedure wavelet filter bank guarantees the perfect reconstruction of signal without any interspectra interference. In simulation for the case of speech signal added additive white gaussian noise, the suggested algorithm shows better performance than that of conventional NLMS algorithm at high SNR.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1311-1319
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• 1990

For the purpose of preventing the flow undulation in the cascade of steam turbine, the blades are made into a constant expansion rate in static pressure. And the flow in those cascades is transonic or supersonic in the range of 0.7-2.0 in Mach number. As a consequence, an oblique shock wave, known as inner or outer edge shock wave, arises in the flow of cascades. Especially when the steam in cascades is in a state of high wetness, nonequilibrium condensation and condensation shock wave occur, and they give rise to an interference with oblique shock wave. In the present study the case of expansion of moist air through a supersonic nozzle of constant expansion rate, which behaves similar to that of wet steam, was adopted. The effect of nonequilibrium condensation on the oblique shock wave generated by placing the wedge into the supersonic part of the nozzle was investigated. Furthermore, the relationship between nonequilibrium condensation zone and incident point of the oblique shock wave, oblique shock wave angle, the variations of angles of incident and reflected shock waves due to the variation of initial stagnation supersaturation and the relationship between the height of Mach stem and initial stagnation supersaturation are discussed.