Determination of Enantiomeric Impurity of Etodolac by Capillary Electrophoresis using (2-Hydroxypropyl)-$\beta$-cyclodextrin

Dung, Phan Thanh,Ko, Mi-Young,Choi, Hyun-Ju,Sin, Kwan-Seog,Kim, Kyeong-Ho 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.9

A capillary electrophoresis method was developed to determine the impurity of etodolac enantiomers. (2-Hydroxypropyl)-$\beta$-cyclodextrin (HP-$\beta$-CD) was used as a chiral selector and ketoprofen as an internal standard to improve the peak area precision. The seperation of the etodolac enantiomers was achived within 35 min at $15^{\circ}C$ and its highest resolution was about 4.0 using phosphate buffer (0.1 M, pH 6.0) with 15 mM HP-$\beta$-CD and UV detection at 225 nm with a reference wavelength at 360 nm. This method allowed determination of 0.2% of (R)-(-)-etodolac in (S)-(+)-etodolac and method validation showed adequate linearity over the required range.

Preparative Resolution of Etodolac Enantiomers by Preferential Crystallization Method

Phan Thanh Dung,Tran Quoc Trung,Kyeong Ho Kim 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.10

Pure enantiomers are of large interest for several industries. This study was aimed to establish a method for separation of etodolac enantiomers by preferential crystallization after a conglomerate formation of its derivatives. S-(+)-etodolac and R-(-)-etodolac enantiomers were both prepared by classical resolution via crystallization of diastereoisomeric salt with (-)-brucine and (-)-cinchonidine. Enantiomeric purity of etodolac was determined by HPLC method using Chiralcel OD-H column. The pure diastereomeric salt collected from repeated recrystallization was further fractionated by liquid-liquid extraction to pure enantiomers. Etodolac enantiomers were recovered with overall yield more than 20% and the purities were over 99.9%.

Natural Scene Text Segmentation Using Spectral Clustering with HSV Color Feature

Phan Thi My Dung(반티미융),Soo Hyung Kim(김수형),In Seop Na(나인섭) 한국정보과학회 2013 한국정보과학회 학술발표논문집 Vol.2013 No.6

Triangulation Based Skeletonization and Trajectory Recovery for Handwritten Character Patterns

( Dung Phan ),( In-seop Na ),( Soo-hyung Kim ),( Guee-sang Lee ),( Hyung-jeong Yang ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.1

In this paper, we propose a novel approach for trajectory recovery. Our system uses a triangulation procedure for skeletonization and graph theory to extract the trajectory. Skeletonization extracts the polyline skeleton according to the polygonal contours of the handwritten characters, and as a result, the junction becomes clear and the characters that are touching each other are separated. The approach for the trajectory recovery is based on graph theory to find the optimal path in the graph that has the best representation of the trajectory. An undirected graph model consisting of one or more strokes is constructed from a polyline skeleton. By using the polyline skeleton, our approach accelerates the process to search for an optimal path. In order to evaluate the performance, we built our own dataset, which includes testing and ground-truth. The dataset consist of thousands of handwritten characters and word images, which are extracted from five handwritten documents. To show the relative advantage of our skeletonization method, we first compare the results against those from Zhang-Suen, a state-of-the-art skeletonization method. For the trajectory recovery, we conduct a comparison using the Root Means Square Error (RMSE) and Dynamic Time Warping (DTW) in order to measure the error between the ground truth and the real output. The comparison reveals that our approach has better performance for both the skeletonization stage and the trajectory recovery stage. Moreover, the processing time comparison proves that our system is faster than the existing systems.

Improvement of ASIFT for Object Matching Based on Optimized Random Sampling

Phan, Dung,Kim, Soo Hyung,Na, In Seop The Korea Contents Association 2013 International Journal of Contents Vol.9 No.2

This paper proposes an efficient matching algorithm based on ASIFT (Affine Scale-Invariant Feature Transform) which is fully invariant to affine transformation. In our approach, we proposed a method of reducing similar measure matching cost and the number of outliers. First, we combined the Manhattan and Chessboard metrics replacing the Euclidean metric by a linear combination for measuring the similarity of keypoints. These two metrics are simple but really efficient. Using our method the computation time for matching step was saved and also the number of correct matches was increased. By applying an Optimized Random Sampling Algorithm (ORSA), we can remove most of the outlier matches to make the result meaningful. This method was experimented on various combinations of affine transform. The experimental result shows that our method is superior to SIFT and ASIFT.

Improvement of ASIFT for Object Matching Based on Optimized Random Sampling

Dung Phan,Soo Hyung Kim,In Seop Na 한국콘텐츠학회(IJOC) 2013 International Journal of Contents Vol.9 No.2

This paper proposes an efficient matching algorithm based on ASIFT (Affine Scale-Invariant Feature Transform) which is fully invariant to affine transformation. In our approach, we proposed a method of reducing similar measure matching cost and the number of outliers. First, we combined the Manhattan and Chessboard metrics replacing the Euclidean metric by a linear combination for measuring the similarity of keypoints. These two metrics are simple but really efficient. Using our method the computation time for matching step was saved and also the number of correct matches was increased. By applying an Optimized Random Sampling Algorithm (ORSA), we can remove most of the outlier matches to make the result meaningful. This method was experimented on various combinations of affine transform. The experimental result shows that our method is superior to SIFT and ASIFT.

Modified Decentralized Control for Multiphase Converters

Quoc-Dung Phan,An-Nhuan Le,Dinh-Tuyen Nguyen,Minh-Thien Nguyen,Guillaume Gateau 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

In this paper, the modified decentralized modulation for the control of multiphase converters using phase-shifted carriers is presented. In difference of principle using local interconnections from two neighbor independent elementary controllers in the conventional decentralized control, the proposed method uses local informations from only one neighbor independent elementary controller allowing them to self-align their own carriers regardless the number of actives cells. Moreover, the same principle is applied for decentralized current control in the parallel phases in order to achieve a perfect sharing of the output current. The simulation results show the feasibility and effectiveness of the proposed method.

Determination of the L-Enantiomer of Nateglinide in Pharmaceutical Formulations by Micellar Electrokinetic Chromatography

Thanh Dung Phan,Ngoc Hoan Nguyen,Dae Joong Kim,Yong-Jae Lee,Seung-Ho Choi,김경호 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.12

An analytical micellar electrokinetic chromatographic method was developed and validated for the determination of the L-enantiomer of nateglinide. Separations were carried out in a 50 μm, 64.5/56 fused-silica capillary. The optimized conditions included 75 mM borate buffer, pH 9.2, containing 50 mM of sodium dodecyl sulfate and 25 mg/mL of methyl-β-cyclodextrin as background electrolyte, an applied voltage of 20 kV and a temperature of 15, UV detector at 210 nm. The assay was validated for the L-enantiomer of nateglinide. The limit of detection and quantification were 0.07 and 0.2% respectively. Intraday precision was ranged between 0.12 and 1.7%. Interday precision ranged between 0.73 and 1.73%. The assay was applied to the determination of the L-enantiomer of nateglinide in pharmaceutical formulations.

Carbon-Nanotube Growth over Iron Nanoparticles Formed on CaCO3 Support by Using Hydrogen Reduction

Nguyen Duc Dung,Nguyen Van Chuc,Ngo Thi Thanh Tam,Nguyen Hong Quang,Phan Hong Khoi,Phan Ngoc Minh 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Carbon nanotubes (CNTs) were grown by chemical vapor deposition on a mixture of iron salt and CaCO3. Salt mixtures of Fe(NO₃)₃9H₂O/CaCO₃ and FeCl₃6H₂O/CaCO₃ with various Fe weight contents were used as catalysts for growing the CNTs. A scanning electron microscope study revealed that the CNTs were densely grown on the Fe(NO₃)₃9H₂O/CaCO₃ catalyst containing 5 wt.% Fe. The effect of growth temperature on the segregation of Fe nanoparticles formed by hydrogen reduction is discussed. The result shows that 800 ℃ is the optimal temperature for the formation of Fe nanoparticles over which CNTs grow with the highest yield of 78.61 %. A raman spectroscope and a scanning transmission electron microscope were utilized to characterize the multiwall structure of the CNTs. The 92.16 % purity of the CNTs was determined by using thermal gravimetric analysis. Carbon nanotubes (CNTs) were grown by chemical vapor deposition on a mixture of iron salt and CaCO3. Salt mixtures of Fe(NO₃)₃9H₂O/CaCO₃ and FeCl₃6H₂O/CaCO₃ with various Fe weight contents were used as catalysts for growing the CNTs. A scanning electron microscope study revealed that the CNTs were densely grown on the Fe(NO₃)₃9H₂O/CaCO₃ catalyst containing 5 wt.% Fe. The effect of growth temperature on the segregation of Fe nanoparticles formed by hydrogen reduction is discussed. The result shows that 800 ℃ is the optimal temperature for the formation of Fe nanoparticles over which CNTs grow with the highest yield of 78.61 %. A raman spectroscope and a scanning transmission electron microscope were utilized to characterize the multiwall structure of the CNTs. The 92.16 % purity of the CNTs was determined by using thermal gravimetric analysis.

Synthesis of Carbon Nanotubes on Steel Foils

Nguyen Van Chuc,Nguyen Duc Dung,Phan Ngoc Hong,Le Dinh Quang,Phan Hong Khoi,Phan Ngoc Minh 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Carbon nanotubes (CNTs) were synthesized by using a thermal chemical vapor deposition (CVD) at 800 ℃ in a mixture of C₂H₂, H₂ and N₂ gases with steel foils as both catalysts and substrates. More than 2 grams of CNTs were grown on approximately 7 grams of steel foil with a 0.5 cm² surface area after 30 minutes of growth. The effects of CVD parameters, such as the growth temperature and the deposition time, on the size and the morphology of the CNTs were studied using scanning electron microscopy (SEM). We found that the optimized temperature and growth time for having high quality CNTs were 800 ℃ and 30 minutes, respectively. The purity of the CNTs was evaluated by using thermogravimetric analysis (TGA) and the result showed that the carbon content was approximately 93 wt.%. The graphite crystallinity of the CNTs was analyzed by using Raman spectroscopy. The steel foil was found to maintain its catalytic behavior after several growths. The technique holds great promise for use in mass production (approximately 120 grams CNTs per day) with signicantly reduced cost. Carbon nanotubes (CNTs) were synthesized by using a thermal chemical vapor deposition (CVD) at 800 ℃ in a mixture of C₂H₂, H₂ and N₂ gases with steel foils as both catalysts and substrates. More than 2 grams of CNTs were grown on approximately 7 grams of steel foil with a 0.5 cm² surface area after 30 minutes of growth. The effects of CVD parameters, such as the growth temperature and the deposition time, on the size and the morphology of the CNTs were studied using scanning electron microscopy (SEM). We found that the optimized temperature and growth time for having high quality CNTs were 800 ℃ and 30 minutes, respectively. The purity of the CNTs was evaluated by using thermogravimetric analysis (TGA) and the result showed that the carbon content was approximately 93 wt.%. The graphite crystallinity of the CNTs was analyzed by using Raman spectroscopy. The steel foil was found to maintain its catalytic behavior after several growths. The technique holds great promise for use in mass production (approximately 120 grams CNTs per day) with signicantly reduced cost.