• Analytical Science and Technology
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• v.19 no.1
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• pp.31-38
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• 2006

Micellar electrokinetic capillary chromatography(MECC) and HPLC with ion-pairing mechanism were applied for the separation of the well known environmental wastes from dye industry. These compounds include H-acid, J-acid, ${\gamma}$-acid, orthanilic acid, sulfanilic acid and 2-naphthylamine-1,5-disulfonic acid, and are known to be the diazo components of the azo dye. MECC method was also applied to separate few acid dyes including Acid Orange 7, Acid Orange 5 and Acid Blue 92 and direct dye such as Direct Red 80. Informations about the diazo components of any azo dye could be obtained by comparison of electropherogram of the reduction solution of a given dye with those obtained from standard materials such as H-acid, J-acid, ${\gamma}$-acid, orthanilic acid, sulfanilic acid and 2-naphthylamine-1,5-disulfonic acid. It has been concluded that MECC and HPLC with ion-pairing mechanism could be successfully applied for the analysis of unknown dyes and their diazo components.

• Hip & pelvis
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• v.36 no.3
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• pp.196-203
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• 2024

Purpose: The direct anterior approach (DAA) for conducting total hip arthroplasty (THA) is gaining popularity worldwide. However, careful selection of patients and surgeon experience are important. Although promising outcomes have been reported in international studies, research on DAA in Southern and Southeast Asia has been limited. Materials and Methods: This prospective study included 157 patients who underwent THA using the DAA between January 2019 and June 2022. The patients were divided into three groups for the comparison. Data on preoperative, intraoperative, and postoperative variables were acquired. Improvement of the surgeon's performance to use of a DAA approach was examined using the CUSUM (cumulative summation method). Results: The mean age of the patients was 43.9 years. Differences in intraoperative variables and complications were observed among the three groups, and improved outcomes were reported in later cases. Functional outcomes showed significant improvement, and no differences were observed between groups. The results of learning curve analysis indicated a shift towards consistent success after the 82nd case, reaching an acceptable rate of failure by the 118th case. Conclusion: The findings of this study suggest that DAA can offer benefits but there is a learning curve. Complications were initially high but began decreasing after approximately 80 cases. Careful selection of patients is critical, particularly in the effort to minimize being presented with a challenging case. This study provides insights that may be helpful to surgeons when considering DAA; however, further study is warranted.

• Journal of Communications and Networks
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• v.5 no.4
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• pp.354-364
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• 2003

A general method for the evaluation of the symbol error probability (SER) of ultra wideband (UWB) systems with various kind of modulation schemes (N-PAM, M-PPM, Bi-Orthogonal), in presence of multipath channel, multiuser and strong narrowband interference, is presented. This method is shown to be able to include all the principal multiaccess techniques proposed so far for UWB, time hopping (TH), direct sequence (DS) and optical orthogonal codes (OOC). A comparison between the performance of these multiple access and modulation techniques is given, for both ideal Rake receiver and minimum mean square error (MMSE) equalizer. It is shown that for all the analyzed multiple access schemes, a Rake receiver exhibits a high error floor in presence of narrowband interference (NBI) and that the value of the error floor is in-fluenced by the spectral characteristics of the spreading code. As expected, an MMSE receiver offers better performance, representing a promising candidate for UWB systems. When the multiuser interference is dominant, all multiple access techniques exhibit similar performance under high-load conditions. If the number of users is significantly lower than the spreading factor, then DS outperforms both TH and OOC. Finally 2PPM is shown to offer better performance than the other modulation schemes in presence of multiuser interference; increasing the spreading factor is proposed as a more effective strategy for SER reduction than the use of time diversity.

• Smart Structures and Systems
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• v.25 no.2
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• pp.123-133
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• 2020

Compressive sensing (CS) is a newly developed data acquisition and processing technique that takes advantage of the sparse structure in signals. Normally signals in their primitive space or format are reconstructed from their compressed measurements for further treatments, such as modal analysis for vibration data. This approach causes problems such as leakage, loss of fidelity, etc., and the computation of reconstruction itself is costly as well. Therefore, it is appealing to directly work on the compressed data without prior reconstruction of the original data. In this paper, a direct approach for modal analysis of damped systems is proposed by decomposing the compressed measurements with an appropriate dictionary. The damped free vibration function is adopted to form atoms in the dictionary for the following sparse decomposition. Compared with the normally used Fourier bases, the damped free vibration function spans a space with both the frequency and damping as the control variables. In order to efficiently search the enormous two-dimension dictionary with frequency and damping as variables, a two-step strategy is implemented combined with the Orthogonal Matching Pursuit (OMP) to determine the optimal atom in the dictionary, which greatly reduces the computation of the sparse decomposition. The performance of the proposed method is demonstrated by a numerical and an experimental example, and advantages of the method are revealed by comparison with another such kind method using POD technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.420-427
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• 2006

The structural and leakage integrity of steam generator tubes should be sustained against all postulated loads even if a crack is present. During the past three decades, most of the efforts with respect to integrity evaluation of steam generator tubes have been focused on limit load solutions but, recently, the applicability of elastic-plastic fracture mechanics was examined cautiously due to its effectiveness. The purpose of this paper is to introduce a testing method to estimate fracture resistance characteristics of steam generator tubes with a through-wall crack. Due to limited thickness and diameter, inevitably, the steam generator tubes themselves were tested instead of standard specimen or alternative ones. Also, a series of three dimensional elastic-plastic finite element analyses were carried out to derive closed-form estimation equations with respect to J-integral and crack extension for direct current potential drop method. Since the effectiveness of $J_{IC}$ as well as J-R curves was proven through comparison with those of standard specimens taken from pipes, it is believed that the proposed scheme can be utilized as an efficient tool for integrity evaluation of cracked steam generator tubes.

• Journal of Veterinary Clinics
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• v.25 no.4
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• pp.274-279
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• 2008

This study was performed to investigate the best staining method for the somatic cell classification of dairy goat milk. Dairy goat milk samples, which were collected randomly from a dairy goat farm in Jeollanam-do, South Korea, were stained and analyzed with direct microscopic method, using 5 different staining methods; Wright's stain, Giemsa stain, Diff-quik stain, Newman's stain and Pyronin Y-Methyl Green stain, respectively. Among them, The Newman's staining was found to be the most rapid and effective method, for it required the shortest time for staining and provided the easiest way to classify somatic cells.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.9 s.240
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• pp.1225-1234
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• 2005

Mode I stress intensity factor $(K_I)$ of Notched Ring Test(NRT) specimen for measuring slow crack growth resistance was found using finite-element method. The theoretical $K_I$ value of NRT was not available in any references and could not be solved analytically. At first, in order to verify the accuracy of the finite-element approach, published $K_I$ values of several cracks were calculated and compared with finite-element results. The results were in good agreement within inherent errors of theoretical $K_I$. Finally the mode I stress intensity factor of NRT was found using 2- and 3-dimensional finite-element methods and expressed as a function of the applied load. This enabled direct comparison of resistance to slow crack growth between NRT and Notched Pipe Test(NPT), which employ different loading regime.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.816-821
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• 2003

The pumping characteristics of a disk-type drag pump (DTDP) from free molecular flow region to the slip flow region are calculated by the direct simulation Monte Carlo (DSMC) method. In this study, the pumping performance is studied numerically for several channel depths. The interaction between molecules is modeled by variable hard-sphere (VHS). The no time counter method is used as a collision sampling technique. The clearance between rotor and stator is considered an effect on performance. Spiral channels are cut on both upper and lower sides of rotating disks, and stationary disks are planar. A three-dimensional DSMC method for the analysis of steady rarefied flows in a single-stage DTDP has been developed. Velocity and density fields were obtained by the DSMC simulation in the rotor. The present experimental data in the outlet pressure range of $7.5{\times}10^{-3}{\sim}4$ Torr were compared with the DSMC results in the single-stage DTDP. Comparison between the experimental data and DSMC results showed good agreement.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2002.11a
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• pp.97-117
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• 2002

A chemoinfometrical method for quantitative determination of crystal content of indomethacin (IMC) polymorphs based on fourie-transformed near-infrared (FT-NIR) spectroscopy was established. A direct comparison of the data with the ones collected from using the conventional powder X-ray diffraction method was performed. Pure $\alpha$ and ${\gamma}$ forms of IMC were prepared using published methods. Powder X-ray diffraction profiles and NIR spectra were recorded for six kinds of standard materials with various content of ${\gamma}$ form IMC. The principal component regression (PCR) analyses were performed based on normalized NIR spectra sets of standard samples of known content of IMC ${\gamma}$ form. A calibration equation was determined to minimize the root mean square error of the prediction. The predicted ${\gamma}$ form content values were reproducible and had a relatively small standard deviation. The values of ${\gamma}$ form content predicted by two methods were in close agreement. The results were indicated that NIR spectroscopy provides for an accurate quantitative analysis of crystallinity in polymorphs compared with the results obtained by conventional powder X-ray diffractometry.

• Bulletin of the Korean Chemical Society
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• v.32 no.10
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• pp.3561-3565
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• 2011

A rapid and inexpensive method was developed for the determination of trace silver in geological samples by using sulfhydryl cotton coupled with ICP-MS. The interferences such as $^{90}Zr$, $^{92}Mo$ and $^{93}Nb$ on silver were investigated in detail. Sulfhydryl cotton was found to be an effective adsorbent for separation of interferences for Ag in the solutions. Excellent agreements with the certified values were obtained for all the certified reference materials. The memory effects of Ag by ICP-MS were examined by using different agents, including water, nitric acid, and HCl-thiourea to all standards/samples. The agents also acted as cleansing solutions. A combination of HCl with thiourea gave the minimum memory effect. For comparison of results, a proposed Chinese Geology Survey procedure DC-ARC-AES and a direct determination pretreatment method of ICP-MS (water bath- auqa regia digestion) were studied. Under optimal conditions, the detection limits of our method for $^{107}Ag$ and $^{109}Ag$ were 1.2 ng/g and 1.3 ng/g, which offered much better accuracy for some difficult analysis geological samples such as GBW07604, GBW07605.