• Title/Summary/Keyword: P-V curve

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Electrocatalytic Oxidation of NADH at Electrodes of Self-assembled Monolayers Modified with Dopamine (도파민으로 수식된 SAMs 전극에서 NADH의 전기촉매에 의한 산화)

  • Cha, Seong-Keuck
    • Journal of the Korean Chemical Society
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    • v.48 no.2
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    • pp.151-155
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    • 2004
  • The self-assembled mololayers(SAMs)were prepared with cysteine(cys) and subsequently coupled with dopamine(dopa) containing quinone functionality on the gold modified electrodes. The SAMs annealed in ethanol for 6 hours gave a better shaped cyclic voltammogram which had a 0.28 V of formal potential and same redox potential in 0.1M phosphate buffer(pH=7.10). The electrodes were employed to determine concentration of HADH with the result that calibration curve exhibited an excellent correlation(${\geq}$ 0.993) for the concentrations ranging up to 5.0${\times}10^{-4}$ M.

Liquid Chromatography-Tandem Mass Spectrometry for the Determination of Lithospermic Acid B in Rat Serum

  • Kim, Hui-Hyun;Ji, Hye-Young;Lee, Hye-Won;Kim, Youn-Chul;Sohn, Dong-Hwan;Lee , Hye-Suk
    • Archives of Pharmacal Research
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    • v.27 no.12
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    • pp.1202-1206
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    • 2004
  • A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/ MS) method for the determination of lithospermic acid B (LSB) in rat serum was developed. LSB and internal standard, 7-hydroxy-3-phenyl-chromen-4-one (HPC) were extracted from rat serum with methyl-tert-butyl ether at acidic pH and analyzed on a Luna $C_8$ column with the mobile phase of acetonitrile-ammonium formate (10 mM, pH 6.5) (50:50, v/v). The analytes were detected using a negative electrospray ionization tandem mass spectrometry in the multiple- reaction-monitoring mode. The standard curve was linear $(r^2 = 0.997)$ over the concentration range of 10.0-500 ng/mL. The coefficient of variation and relative error for intra- and interassay at three QC levels were 1.1~6.2% and -10.3~-2.7%, respectively. The recovery of LSB from serum sample ranged from 73.2 to 79.5%, with that of HPC (internal standard) being 75.1 %. The lower limit of quantification for LSB was 10 ng/mL using 50 ${\mu}L$ of serum sample.

A Study on the Characteristic of n-ZnO:In/p-Si (111) Heterostructure by Pulsed Laser Deposition (PLD 법으로 증착된 n-ZnO:In/p-Si (111) 이종접합구조의 특성연구)

  • Jang, Bo-Ra;Lee, Ju-Young;Lee, Jong-Hoon;Kim, Jun-Je;Kim, Hong-Seung;Lee, Dong-Wook;Lee, Won-Jae;Cho, Hyeong-Kyun;Lee, Ho-Seong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.5
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    • pp.419-424
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    • 2009
  • ZnO films doped with different contents of indium ($0.1{\sim}10$ at.%) were deposited on Si (111) substrate by Pulsed Laser Deposition (PLD). The structural, electrical and optical properties of the films were investigated using XRD, AFM, Hall and PL measurement. Results showed that un-doped ZnO film had (002) plane as the c-axis orientated growth, whereas indium doped ZnO films exhibited the peak of (002) and the weak (101) plane. In addition, in the indium doped ZnO films, the electron concentration is ten times higher than that of un-doped ZnO film, while the resistivity is ten times lower than that of un-doped ZnO film. The indium doped ZnO films have UV emission about 380 nm and show a red shift with increasing contents of indium. The I-V curve of the fabricated diode show the typical diode characteristics and have the turn on voltage of about 2 V.

A Study on Carrier Injection and Trapping by the High Field for MOS(Metal-$Al_2O_3$-p Si$) Structure (Metal-$Al_2O_3$-p Si$의 MOS 구조에 있어서 고전계에의한 Carrier주입과 트랩에 관한 연구)

  • Park, Sung Hee;Sung, Man Young
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.24 no.1
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    • pp.102-109
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    • 1987
  • This study is carrier out to investigate the carrier injection and the characteristics of trapping for the CVD deposited Al2O3 film on Si substrates. Samples used are metal -Al2O3-Si Structure in which metal field plates are used with Aluminium or God. Canier injection and trapping, which result in flat band voltalge shift, occur at fields as low as 1~2 MV/cm. An approximate method is proposed for computing the location of the centroid of the trapped electrons in this paper. Results show that carriers are trapped near the injecting interface at fields less than about 5MV/cm. Because of continued charging, a steady state can not be reached. Therefore the unique I-V curve is obtained when the traps are initially empty. By utilization of applied voltage on each point of the fresh device sample, it is measured the I-V surves for two polarities of applied voltage. The current densities observed in the Al2O3 films are much larger than those obtained in SiO2.

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Seismic performance evaluation of existing road tunnels based on revised seismic design code (개정된 내진설계기준에 기반한 기존 도로 터널의 내진 성능 평가)

  • Gyu-Phil Lee;Du-Hee Park;Ji-Eun Kang
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.6
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    • pp.525-540
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    • 2023
  • Because of a new seismic design code has been enacted in 2023, there is a need to evaluate whether the road tunnels in operation satisfies the requirements of the new code. Four tunnels that are considered to be most susceptible to damage. Time history analyses are performed to quantify their seismic performances. The input ground motions generated to fit both 2007 and 2023 codes are used to evaluate the effect of the motions on the calculated responses. The analyses show that all tunnels perform favorably and satisfies the requirements successfully. Therefore, retrofit or reinforcement are deemed as unnecessary.

THE EFFECT OF SOME CANAL PREPARATION TECHNIQUES ON THE SHAPE OF ROOT CANALS (수종의 근관형성 방법이 근관 형태에 미치는 영향)

  • Lee, Ji-Hyeon;Cho, Yong-Bum
    • Restorative Dentistry and Endodontics
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    • v.24 no.2
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    • pp.337-345
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    • 1999
  • The purpose of this study was to compare the shape of root canal after instrumentation with some engine driven NiTi files. Thirty narrow and curved canals(15-35 degree) of mesial canals of extracted human mandibular first molars were divided into three groups. Group 1: After radicular access with Gates Glidden drill, apical shaping using step back method with Flexo file Group 2: After radicular access with Gates Glidden drill, apical shaping with Profile .04 Group 3: Canal shaping with GT file and Profile .04. Using modified Bramante technique, the root was sectioned at 2 mm from apical foramen, height of curvature, 2 mm from canal orifice. Canal centering ratio, amount of transport, amount of dentin removed, shape of canal were measured and statistical analysis is done using SPSS Program V 7.5. The results were as follows: 1. Canal centering ratio of group 3 was the lowest at coronal part, but there was no statistical difference. Centering ratio of group 2 was the lowest at curve part, and there was statistical difference between group 1(P<0.05). Centering ratio of group 2 was the lowest at apical part, but there was no statistic difference. 2. Amount of transport of group 3 was the lowest at coronal part, but there was no statistical difference. Amount of transport of group 2 was the lowest at curve part, and there was statistical difference between group 1(P<0.05). Amount of transport of group 3 was the lowest at apical part, and there was statistical difference between group 1 and group 2, group 1 and group 3(P<0.05). 3. Amount of dentin removed of group 3 was the lowest at coronal part, bur there was no statistical difference. Amount of dentin removed of group 2 was the lowest at curve part, but there was no statistical difference. Amount of dentin removed or group 2 was the lowest at apical part, and there was statistical difference between group 1 and group 2, group 1 and group 3(P<0.05). 4. The shape of the canals after instrumentation varied among the groups. The majority of canals at coronal and curve part for group 1 were round in shape(7 in 10), those at apical part were oval(8 in 10). The majority of canals at coronal part for group 2 were round in shape(7 in 10) and there was no difference in the number of shape at other part. There was no difference in the number of shape at every part for group 3. As above results, NiTi rotary instrumentation showed a trend to remain more centered in the canal than SS file instrumentation. At using NiTi file, coronal shaping with Gates Glidden drill was not statistically different from shaping with GT file. But shaping with GT file showed tapered canals, so it may be said that shaping with GT file is a safe and valuable instrumentation method.

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Microanalytical Study of Sodium Alginate by Differential Pulse Stripping Voltammetry (시차 펄스 벗김전압전류법을 이용한 Sodium Alginate의 미량분석 연구)

  • Kang, Dae-Joon;Yun, Young-Ja
    • Journal of the Korean Chemical Society
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    • v.44 no.2
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    • pp.109-114
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    • 2000
  • In this study, the optimum analytical condition of Differential pulse Voltammetry for the polymeric Sodium Alginate was studied and its reduction funtional groups were confirmed using Cyclic Vol-tammetry and IR spectroscopy. Optimum conditions were as followed; mercury drop size : medium size, accumulation time : 60sec, accumulation potential : -0.20V vs Ag/AgCl, scan rate : 100mV/sec, supporting electrolyte : 0.10M $NaClO_4$(pH 6.8). After polymeric Sodium Alginate was hydrolized at $100^{\circ}C$ in acidic condition, the current peaks of oligomer were compared with current peak of polymeric Sodium Alginate. In this optimum condition, calibration curve of polymer Sodium Alginate showed good linearity from 0.50ppm to 4.0ppm where as oligomeric Sodium Alginate showed good linearity from 0.05ppm to 0.24ppm.

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Calculation of Pressure Rise in the Puffer Cylinder of EHV GCB Without Arc (무부하시의 초고압 GCB의 파퍼실린더 내부의 상승압력 계산)

  • Park, K.Y.;Song, K.D.;Choi, Y.K.;Shin, Y.J.;Song, W.P.;Kang, J.H.
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1559-1561
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    • 1994
  • At present, the principle of puffer action in high current interruption is adopted in almost of the EHV(Extra High Voltage) and UHV(Ultra High Voltage) GCB(Gas Circuit Breakers). The thermal interruption capability of these GCBs critically depends on the pressure rise in the puffer cylinder at current zero. The pressure rise in the puffer cylinder depends on the puffer cylinder volume, flow passage and leakage area in the interrupter, stroke curve etc. Recently commercial CFD(Computational Fluid Dynamics ) packages have been widely adopted to calculate the pressure distribution in the interrupter. However, there are still several problems with it, e.g. very expensive price, moving boundary problem, computation time, difficulty in using the package etc. Thus, the calculation of the puffer cylinder pressure in simple and relatively correct method is essential in early stage of GCB design. In these paper, the model ing technique and computed results for EHV class GCB (HICO, 145kV 40kA and 362kV 40kA GCB) are presented and compared with available measured results.

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Two Mode Maximum Power Point Tracking for Photovoltaic System

  • Limsakul, Chamnan;Ukakimaphun, Prapas;Prapanavarat, Cherdchai;Chenvidhya, Dhirayut
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.143-148
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    • 2004
  • This paper presents the two modes for maximum power point tracking of the photovoltaic system. The method combines the merits of the two methods consisting of the open circuit method and the three point weight comparison method. The maximum point found by this method is exactly than by the open circuit method. By the simulation results, the actual maximum point can be found that is better than the Perturb and Observe (P&O) method or the three point weight method only one method, especially, in the case of non regular pattern of Power-Voltage (P-V) curve.

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Center of Gravity and a Characterization of Parabolas

  • KIM, DONG-SOO;PARK, SOOKHEE;KIM, YOUNG HO
    • Kyungpook Mathematical Journal
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    • v.55 no.2
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    • pp.473-484
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    • 2015
  • Archimedes determined the center of gravity of a parabolic section as follows. For a parabolic section between a parabola and any chord AB on the parabola, let us denote by P the point on the parabola where the tangent is parallel to AB and by V the point where the line through P parallel to the axis of the parabola meets the chord AB. Then the center G of gravity of the section lies on PV called the axis of the parabolic section with $PG=\frac{3}{5}PV$. In this paper, we study strictly locally convex plane curves satisfying the above center of gravity properties. As a result, we prove that among strictly locally convex plane curves, those properties characterize parabolas.