• Journal of Pharmaceutical Investigation
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• v.38 no.2
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• pp.135-142
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• 2008

The present study describes the evaluation of the bioequivalence of two atorvastatin tablets, Lipitor $Tablet^{(R)}$ (Pfizer, reference drug) and Atorva $Tablet^{(R)}$ (Yuhan, test drug), according to the guidelines of Korea Food and Drug Administration (KFDA). Forty-nine healthy male Korean volunteers received each medicine at the atorvastatin dose of 40 mg in a $2{\times}2$ crossover study with a two weeks washout interval. After drug administration, serial blood samples were collected at a specific time interval from 0-48 hours. The plasma atorvastatin concentrations were monitored by an high performance liquid chromatography -tandem mass spectrometer (LC-MS/MS) employing electrospray ionization technique and operating in multiple reaction monitoring (MRM) and positive ion mode. The total chromatographic run time was 4.5 min and calibration curves were linear over the concentration range of 0.1-100 ng/mL for atorvastatin. The method was validated for selectivity, sensitivity, linearity, accuracy and precision. $AUC_t$ (the area under the plasma concentration-time curve from time zero to 48hr) was calculated by the linear log trapezoidal rule method. $C_{max}$ (maximum plasma drug concentration) and $T_{max}$ (time to reach $C_{max}$) were complied trom the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed $AUC_t$ and $C_{max}$. No significant sequence effect was found for all of the bioavailability parameters indicating that the crossover design was properly performed. The 90% confidence intervals of the $AUC_t$ ratio and the $C_{max}$ ratio for Atorva $Tablet^{(R)}$ / Lipitor $Tablet^{(R)}$ were ${\log}\;0.9413{\sim}{\log}\;1.0179$ and ${\log}\;0.831{\sim}{\log}\;1.0569$, respectively. These values were within the acceptable bioequivalence intervals of ${\log}\;0.8{\sim}{\log}\;1.25$. Based on these statistical considerations, it was concluded that the test drug, Atorva $Tablet^{(R)}$ was bioequivalent to the reference drug, Lipitor $Tablet^{(R)}$.

• Analytical Science and Technology
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• v.29 no.4
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• pp.179-185
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• 2016

An effective analytical method has been developed for the determination of β-blockers(atenolol, metoprolol and propranolol) and 6 β-lactams(amoxicillin, penicillin G, cefaclor, cefadroxil, cephalexin and cephradine) in water samples using two different cartridges. The samples were extracted by solid-phase extraction (SPE) with the usage of polymeric hydrophile-lipophile balance(HLB cartridges) and strong cation-exchange mixed-mode polymeric sorbent (MCX cartridges). A XDB-C₁₈ column(1.8 μm; 3.0 mm × 100 mm) was used for the sufficient chromatographic resolution. The calibration curves showed good linearity with high correlation coefficients (>0.995). The method detection limits (MDL) and the limits of quantification(LOQ) were from 1.1 to 3.9 ng/L and from 5 to 13 ng/L, respectively. The method was applied for the determination of the target compounds in tributaries and raw water of the Han River and these were found at N.D. to 0.209 μg/L.

• Analytical Science and Technology
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• v.29 no.4
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• pp.202-208
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• 2016

본 연구에서는 사료 첨가제로 이용되고 있는 유기산 7종(formic acid, malic acid, lactic acid, acetic acid, citric acid, fumaric acid, propionic acid)의 동시분석법 개발을 위한 연구를 실시하였다. 7종의 화합물은 표준물질의 Retention time과 UV spectra를 통해 구별하였고, 분석법 검증은 직선성, 민감성, 선택성, 정확성, 정밀성을 통하여 검증하였다. 그 결과로 LOD와 LOQ의 범위가 각각 43~26,755 μg/kg, 12-8,026 μg/kg으로 설정하였고, 평균 회수율이 79.3~95.2%로 우수하게 보였으며, intra-day, inter-day에 대한 전반적인 상대 표준 편차(%RSD)는 3.2% 미만으로 나타났다. 이와 같이 검증된 자료를 통해 유기산의 동시분석에 대한 직선성, 민감성, 선택성, 정확성 및 정밀성을 확인하였고, 높은 수준을 나타냄을 알 수 있었다. 이를 바탕으로 유기산이 검출되는 단미사료 46 가지를 분석에 적용하여 진행하였고, 정량과 동시분석 검출을 위한 방법은 RP-HPLC/UV 검출기를 이용하여 성공적으로 개발되었다. 따라서 본 연구결과를 바탕으로 하여 사료 중의 유기산의 분석이 신속하고 정확해졌을 뿐 아니라, 다른 종류의 사료 또한 이를 적용하여 효율적으로 이용할 수 있을 것으로 판단된다.

• Analytical Science and Technology
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• v.25 no.2
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• pp.152-157
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• 2012

Currently, many types of compound preparations are being used but the quality control guidelines for their use are lacking. In case of single compound drug, the quality control methods are specified in the pharmacopeia. However, there is no method to simultaneously analyze compound preparations. In this study, a simple validated analytical method for HPLC separation of chlorquinaldol and promestriene is introduced. Validation was divided into categories including linearity, precision, accuracy (recovery) and system suitability. The contents of the products which are on the market were monitored using the validated analytical method and the robustness of the analytical method was tested by conducting an inter-laboratory validation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.329-329
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• 2007

Photoconductive poly crystalline lead oxide coated on amorphous thin film transistor (TFT) arrays is the best candidate for direct digital x-ray detector for medical imaging. Thicker films with lessening density often show lower x-ray induced charge generation and collection becomes less efficient. In this work, we present a new methodology used for the high density deposition of PbO. We investigate the structural properties of the films using X-ray diffraction and electron microscopy experiments. The film coatings of approximately $200\;{\mu}m$ thickness were deposited on $2"{\times}2"$ conductive-coated glass substrates for measurements of dark current and x-ray sensitivity. The lead oxide (PbO) films of $200\;{\mu}m$ thickness were deposited on glass substrates using a wet coating process in room temperature. The influence of post-deposition annealing on the characteristics of the lead oxide films was investigated in detail. X-ray diffraction and scanning electron microscopy, and atomic force microscopy have been employed to obtain information on the morphology and crystallization of the films. Also we measured dark current, x-ray sensitivity and linearity for investigation of the electrical characteristics of films. It was found that the annealing conditions strongly affect the electrical properties of the films. The x-ray induced output charges of films annealed in oxygen gas increases dramatically with increasing annealing temperatures up to $500^{\circ}C$ but then drops for higher temperature anneals. Consequently, the more we increase the annealing temperatures, the better density and film quality of the lead oxide. Analysis of this data suggests that incorporation and decomposition reactions of oxygen can be controlled to change the detection properties of the lead oxide film significantly. Post-deposition thermal annealing is also used for densely film. The PbO films that are grown by new methodology exhibit good morphology of high density structure and provide less than $10\;pA/mm^2$ dark currents as they show saturation in gain (at approximate fields of $4\;V/{\mu}m$). The ability to operate at low voltage gives adequate dark currents for most applications and allows voltage electronics designs.

• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.65-76
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• 2013

Traffic accidents at signalized intersections have been increased annually so that it is required to examine the causation to reduce the accidents. However, the current existing accident models were developed mainly by using non-linear regression models such as Poisson methods. These non-linear regression methods lack to reveal the complicated causation for traffic accidents, though they are the right choice to study randomness and non-linearity of accidents. Therefore, it is required to utilize another statistical method to make up for the lack of the non-linear regression methods. This study developed accident prediction models for 4 legged signalized intersections with Poisson methods and compared them with structural equation models. This study used structural equation methods to reveal the complicated causation of traffic accidents, because the structural equation method has merits to explain more causational factors for accidents than others.

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.424-429
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• 2016

Globally, obesity has been recognized as a serious health problem. Recently, slimming foods for weight loss and maintenance were found to contain anti-obesity drugs, their analogues, and prohibited ingredients. To avoid inspections by the Government, structurally modified analogs have been continuously synthesized. For rapid determination of adulterated slimming products, we simultaneously analyzed 21 illegal compounds using liquid chromatography (LC) equipped with photo diode array, and LC coupled with tandem mass spectrometry. The validation of the method was performed with regard to selectivity, linearity, limit of detection, limit of quantification, precision, and accuracy. We purchased 128 samples from the Korean market and online sources in the year 2015. In 31 samples, 3 illegal compounds were detected as follows: 9.9-135.3 mg/g of sibutramine, 0.2-17.5 mg/g of yohimbine, and 1.8 mg/g of icariin. This simultaneous detection method might prove to be a simple and rapid analysis for monitoring illegal compounds in slimming foods.

• Clinical and Experimental Reproductive Medicine
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• v.44 no.3
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• pp.132-140
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• 2017

Objective: Correlations between semen parameters and sperm DNA fragmentation index (DFI) were investigated to identify characteristics of sperm without DNA damage that could be used in selecting sperm for intracytoplasmic sperm injection (ICSI). Pregnancy outcomes were compared to determine whether in vitro fertilization (IVF) or ICSI is a better choice for patients who have sperm with a high-DFI. Methods: Semen analysis was carried out in 388 patients who visited our IVF center for the first time to investigate correlations between sperm DFI and semen parameters. In addition, 1,102 IVF cycles in 867 patients were carried out in the present study; 921 cycles in the low-DFI group (DFI < 30%) and 181 cycles in the high-DFI group ($DFI{\geq}30%$). Both the low- and high-DFI groups were subdivided into IVF and ICSI cycle groups. Results: Sperm DFI showed significant inverse correlations with sperm motility (r = -0.435, p< 0.001) and morphology (r = -0.153, p< 0.05). Sperm DFI also showed significant correlations with rapid motility (r = -0.436, p< 0.001), and the kinetic parameters of average-path velocity (r = -0.403) and linearity (r = -0.412). Although there was no significant difference in the pregnancy rates between IVF (48.6%) and ICSI (44.8%) in the low-DFI group, the pregnancy rate of ICSI cycles (44.8%, p< 0.05) was significantly higher than IVF cycles (25.0%) in the high-DFI group. No significant difference was observed in the abortion rates between the low-DFI (52 of 921, 5.6%) and high-DFI groups (7 of 181, 3.8%). Conclusion: ICSI is a better choice than IVF for improving the pregnancy outcomes of patients who have sperm with a high DFI.

• Research in Plant Disease
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• v.27 no.3
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• pp.120-127
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• 2021

Plant viruses cause significant yield losses, continuously compromising crop production and thus representing a serious threat to global food security. Tomato spotted wilt virus (TSWV) is the most harmful plant virus that mainly infects horticultural crops and has a wide host range. Reverse-transcription quantitative real-time PCR (RT-qPCR) has been widely used for detecting TSWV with high sensitivity, but its application is limited owing to the lack of standardization. Therefore, in this study, a sensitive and accurate reverse transcription droplet digital polymerase chain reaction (RT-ddPCR) method was established for TSWV detection. Additionally, we compared the sensitivities of RT-qPCR and RT-ddPCR for TSWV detection. Specificity analysis of RT-ddPCR for TSWV showed no amplification for main pepper viruses and negative control. TSWV transcripts levels measured by RT-ddPCR and RT-qPCR showed a high degree of linearity; however, the former yielded results that were at least 10-fold more sensitive and detected lower TSWV copy numbers than the latter. Collectively, our findings show that RT-ddPCR provides improved analytical sensitivity and specificity for TSWV detection, making it suitable for identifying low TSWV concentrations in field samples.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.86-92
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• 2019

Polymers with various compositions of azobenzene and hexamethylene groups in the main chain were synthesized by a Schotten-Baumann reaction and their properties were investigated. The chemical structures and physical properties of the synthesized polymers were investigated by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry, thermogravimetric analysis, polarized optical microscopy, and x-ray diffraction. The polymers showed an inherent viscosity of 1.28-1.36 dl/g and were relatively insoluble in most organic solvents. The melt transition temperature increased rapidly with increasing number of azobenzene groups in the polymer. When the azobenzene monomer content was more than 50 mol%, no melting transition occurred below the decomposition temperature. Among the polymers with a melt transition temperature, the MP-A3C7 and MP-A5C5 polymers were liquid crystalline materials and exhibited a nematic phase with weak liquid crystallinity over a wide liquid crystal temperature range. This difference in the properties of the synthesized polymers is likely due to the changes in intermolecular forces resulting from the linearity and polarity of the trans-form of azobenzene.