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121.
Yoon Hee Kwon Hye Sun Gwak Sun Jung Yoon In Koo Chun 《Drug development and industrial pharmacy》2013,39(8):824-829
Doxazosin mesylate is a selective alpha-adrenoreceptor antagonist for the treatment of hypertension and benign prostatic hyperplasia. A simple high performance liquid chromatographic method has been developed and validated for the quantitative determination of doxazosin in plasma. A reversed phase C18 column was used for the separation of doxazosin and prazosin (internal standard) with a mobile phase composed of water ? acetonitrile ? triethylamine (68:32:0.2 v/v, pH 5.0) at a flow rate of 1.2 mL/min. The fluorescence detector was operated at 246 (excitation) and 389 nm (emission). Intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification of 1 ng/mL. Recovery of doxazosin from human plasma was greater than 93.4%. Doxazosin was stable in human plasma under various storage conditions. This method was used successfully for a pharmacokinetic study in plasma after oral administration of multiple 4-mg dose of doxazosin gastrointestinal therapeutic system formulation to 16 healthy volunteers. At steady state the mean area under the curve for a dosing interval and elimination half-life were calculated to be 367.0 ± 63.5 ng · hr/mL and 29.2 ± 4.5 hr, respectively. There was no difference in pharmacokinetic parameters between male and female. 相似文献
122.
Vo-Gia Loc Se-goh Roh Ig Mo Koo Duc Trong Tran Ho Moon Kim Hyungpil Moon Hyouk Ryeol Choi 《Robotics and Autonomous Systems》2010,58(5):666-675
In this paper, a general study on improving adaptability of quadruped walking and climbing robot in complex environment is presented. First, a sensing system composed of range and gyroscope sensors in a novel arrangement is developed. By combining the sensing signals and the internal state of the robot, the surface geometry of the environment is sufficiently reconstructed in real-time. Secondly, a planning algorithm for the robot to overcome the reconstructed environment is conducted. Based on the reshaped surface, the planning algorithm not only provides the exact body trajectory and foot positions but also the adaptability of the robot in a specific environment. A method to improve the adaptability of the walking and climbing robot is also introduced. Thanks to the adherent ability of the robot, the center of gravity of the robot is allowed to move outside the support polygon to increase the reach-ability of the next swing leg. Finally, the effectiveness of the proposed approach is verified by the performances of the experiments in complex environments using a quadruped walking and climbing robot named MRWALLSPECT IV. 相似文献
123.
124.
Jung-Hyuk Koh Mun-Su Ha Soon-Jong Jeong Jae-Sung Song Tae-geun Kim Sang-Mo Koo Jae-geun Ha 《Journal of Electroceramics》2006,16(4):403-406
The solid solution of Pb(Mg,Nb)O3-Pb(Zr,TiO) O3 materials have high piezoelectric constant of 600 ∼650 pC/N and electromechanical coupling coefficient k
p of 0.65. Due to such high piezoelectric constant and electromechanical coupling coefficient, Pb(Mg,Nb)O3-Pb(Zr,TiO)O3 materials have been attracted attentions for the applications of multilayer ceramic actuators. Actuators can be produced
by staking piezoelectric ceramic materials and inner electrodes, alternatively. However, it is difficult to fabricate huge
ceramic actuators without any serious problems during the process conditions. Because ceramic are easily cracked during the
sintering process, due to strikingly different shrinkage rate between the ceramic materials and metal electrodes. In this
research, new jointing methods will be proposed for huge ceramic actuators, and then their electrical properties were investigated.
Time dependent leakage current and impedance spectroscopy were employed to expect device performances. 相似文献
125.
Jung Sang Cho You Na Ko Hye Young Koo Yun Chan Kang 《Journal of materials science. Materials in medicine》2010,21(4):1143-1149
Nanometer size biphasic calcium phosphate (BCP) powders with various Ca/P molar ratios satisfied with appropriate phase ratios of HA/β-TCP were prepared by high temperature flame spray pyrolysis process. The BCP powders had spherical shapes and narrow size distributions irrespective of the ratios of Ca/P. The mean size of the BCP powders measured from the TEM image was 38 nm. The composition ratio of Ca/P was controlled from 1.500 to 1.723 in the spray solution, and required phase ratios of HA/TCP are controlled systematically. The calcium dissolution of the pellets obtained from the BCP powders directly prepared by flame spray pyrolysis in buffer solution increased with the decrease of Ca/P ratios except with the Ca/P ratio of 1.713. The pellet surface with Ca/P ratio of 1.500, which consisted of β-TCP, was eroded dramatically for 7 days. On the other hand, the pellet surface with Ca/P ratio of 1.667 was stable and did not disintegrate after immersion in Tris–HCl buffer solution based on the SEM observation. 相似文献
126.
Abstract Hydrogen annealing damages on properties of PZT capacitors and a role of Ti/Ir hybrid structure top electrodes on capacitors are investigated in this study. It is demonstrated that the capacitors with Ti/Ir structure top electrodes improve a resistance against hydrogen related degradation. As the thickness ratio of Ti/Ir increases, the capacitors show enhanced endurance against hydrogen damages. Especially, PZT (350nm) capacitors with Ti(80nm)/Ir(20nm) hybrid top electrodes show only 26% decrease in nonvolatile polarizations (P?r) under ± 7V, while 67% of P?r of ferroelectric capacitors with Ir top electrodes is reduced after forming gas annealing at 250°C for 10min. Based on the XPS analysis, ferroelectric characteristics of PZT thin film capacitors are degraded by destruction of Pb-O bond into metallic Pb due to hydrogen anneal on the catalytic top electrodes (Ir, Pt). 相似文献
127.
M. S. Anwar Shalendra Kumar Faheem Ahmed Si Nae Heo G. W. Kim Bon Heun Koo 《Journal of Electroceramics》2013,30(1-2):46-50
The magnetocaloric properties of new complex magnetic material La0.65Sr0.35Cu0.1Mn0.9O3, suitable for the Ericsson cycle, have been investigated. For this material, the effect of Cu doping can be attributed to a combination of doping disorder, Cu-Mn super exchange interactions and a site-percolation mechanism, which suppress the metallic conduction and Curie temperature. The Curie temperature decreases to 355 K. The magnetocaloric study exposes a comparable value of the magnetic entropy change for La0.65Sr0.35Cu0.1Mn0.9O3 sample, the value of the maximum entropy change, increases from 1.132 J/kgK to 3.11 J/kgK as magnetic field increases from 1 T to 4 T. A large relative cooling power (RCP) has been observed for La0.65Sr0.35Cu0.1Mn0.9O3. As a result, the studied sample can be considered as potential material for magnetic refrigeration. 相似文献
128.
Performance of traveling-wave electroabsorption modulators depending on microwave properties of waveguides calculated using the FDTD method 总被引:1,自引:0,他引:1
Seungki Nam Yonggyoo Kim Jaehoon Lee Moonil Kim Jichai Jeong 《IEEE journal of selected topics in quantum electronics》2003,9(3):763-769
We present a method to analyze electrical and optical characteristics of traveling-wave electroabsorption modulators (TW-EAMs) using the finite-difference time-domain method. We consider the interaction between electromagnetic fields and optical powers in waveguides in time domain to model electrical and optical behaviors of TW-EAMs. The effects of microwave properties of waveguides on modulation response and output optical power of TW-EAMs are analyzed by the proposed method. The characteristic impedance of TW-EAMs is more important than microwave index to obtain large modulation bandwidth of TW-EAMs when impedance matching techniques are not used. However, effective refractive index match between microwave and lightwave becomes important as the waveguide length increases. The microwave property closely related to the extinction ratio of output optical powers is the microwave loss. When impedance match is achieved by low-impedance termination, the velocity matching between microwave and lightwave becomes important. 相似文献
129.
Imad Hussain S.N. Khan Eun Ji Kim So Eun Jeon Bon Heun Koo 《Ceramics International》2018,44(3):2892-2899
A systematic study focusing on the effect of Niobium (Nb) doping on the structural, magnetic and magnetocaloric properties of Ba2FeMoO6 samples is presented here. The samples of interest Ba2FeMo1?xNbxO6 (0 ≤ x ≤ 0.4) were prepared using the solid state reaction method and were confirmed to possess a cubic structure with Fm-3m space group using the X-ray diffraction analysis and Rietveld refinement. A second order of ferromagnetic phase transition was recorded in both the pure as well as the Nb doped samples using the temperature dependent magnetization and Arrott plots analysis. The pristine Ba2FeMoO6 (BFMO) sample indicated a spontaneous magnetization (34.6 emu/g at 100 K) with a relatively sharp magnetic transition at the Curie temperature (TC) of 315 K as compared to the doped samples. A magnetic entropy change of 0.93 Jkg?1K?1 at an applied magnetic field of 2.5 T was measured for the pure BFMO sample. The doped BFMO samples with Mo partially substituted by Nb however, were observed to effectively modify the TC accompanied by a decrease in magnetization. The results investigated in this work suggest that the magnetic and magnetocaloric properties of the BFMO can be tailored by controlled Nb doping which is of significant importance in order to realize the numerous potential applications of the material in the magnetic refrigeration technology. 相似文献
130.
Tae Y. Kim Kwon M. Koo Gayeong Yun Yangsoo Kim 《Polymer Engineering and Science》2021,61(6):1842-1853
Two types of multi-walled carbon nanotube (MWNT)-based elastomer nanocomposites are used as a sensor material for the detection of gasoline spills by applying the interdigitated electrode (IDE) device. MWNT-g-polyisoprene (PI) and Si-MWNT/natural rubber (NR) are prepared by applying “grafting-from” and “grafting-to” process, respectively. When compared based on the identical condition of gasoline sensing test, the maximum response value to the exposure of gasoline is 17.5 for MWNT-g-PI sensor and 12.9 for Si-MWNT/NR sensor, which reach the maximum in less than 3 min. The MWNT-g-PI sensor selectively detects gasoline, and its response is completely reversible. It shows that the longer chain length of PI brings about the larger response of MWNT-g-PI sensor to gasoline. The sensitivity of MWNT-g-PI sensor highly depends on both how much gasoline is exposed to the sensor and what bias voltage is applied to the IDE device. The IDE sensor using MWNT-g-PI nanocomposites effectively detects gasoline spills. 相似文献