• Title/Summary/Keyword: Reverse electric charge

Search Result 12, Processing Time 0.025 seconds

Removal of Dust in Positive and Negative Plates of Electrode Coated with Activated Carbon (활성탄으로 코팅된 전극에서 분진의 제거)

  • Kim, Kwang Soo;Park, Hyun Chul;Jun, Tae Hwan;Lee, Ju Haeng;Nam, Sang Chul
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.29 no.6
    • /
    • pp.830-837
    • /
    • 2013
  • The purposes of this research are to know the dust removal efficiency according to the changes of gab between positive and negative plates in dust removal chamber. The experiments for dust removal efficiencies were conducted with changing the electrode-plate gab from 2 cm to 1 cm while the electric pressure, influent flow, and linear velocity were kept 5 kV, 80 L/min, and 6 cm/sec, respectively. From the experimental results of the electrode-plate gab of 2 cm, dust removal efficiencies were decreased to as low as about 50%. Attached dust on the surface of electrodes was released due to a reverse electric charge of dust. From the experimental results of the electrode-plate gab of 1 cm, dust removal efficiencies were increased to as high as about 80% due to the dust attachment velocity to the electrodes to be far more fast than influent linear velocity. Finally, to protect a attached dust from occurring a reverse electric charge it is needed to install the non-conductor between positive and negative electrodes and also to remove air humidity.

BLDC motor control method for hybrid electric vehicle (하이브리드 자동차용 BLDC 전동기 제어 방법)

  • Kang, Sin-Won;Jang, Jong-Hoon;Jeong, Ji-Ye;Won, Chung-Yuen
    • Proceedings of the KIEE Conference
    • /
    • 2009.04b
    • /
    • pp.149-151
    • /
    • 2009
  • Hybrid electric vehicle has three operating mode, depending on the operation of the engine and electric motor. According to the speed range of BLDC motor, In hybrid traction mode, both the engine and electric motor deliver to drive train. Battery charge mode, the electric motor operates as generator and is driven by the engine to charge the batteries. In engine alone traction mode, the electric motor is do-energized, and vehicle is propelled by the engine alone. we propose hysteresis current control technique to maintain constant speed in the motor load torque at the reverse direction. The proposed method is verified by using Matlab Simulink software.

  • PDF

Hot-Carrier-Induced Degradation in Submicron MOS Transistors (Submicron MOS 트랜지스터의 뜨거운 운반자에 의한 노쇠현상)

  • 최병진;강광남
    • Journal of the Korean Institute of Telematics and Electronics
    • /
    • v.25 no.7
    • /
    • pp.780-790
    • /
    • 1988
  • We have studied the hot-carrier-induced degradation caused by the high channel electric field due to the decrease of the gate length of MOSFET used in VLSI. Under DC stress, the condition in which maximum substrate current occures gave the worst degradation. Under AC dynamic stress, other conditions, the pulse shape and the falling rate, gave enormous effects on the degradation phenomena, especially at 77K. Threshold voltage, transconductance, channel conductance and gate current were measured and compared under various stress conditions. The threshold voltage was almost completely recovered by hot-injection stress as a reverse-stress. But, the transconductance was rapidly degraded under hot-hole injection and recovered by sequential hot-electron stress. The Si-SiO2 interface state density was analyzed by a charge pumping technique and the charge pumping current showed the same trend as the threshold voltage shift in degradation process.

  • PDF

Electrical characteristics simulation of thyristor devices for HVDC transmission (HVDC용 사이리스터 소자의 전기적 특성 simulation 연구)

  • Kim, Sang-Cheol;Seo, Kil-Soo;Kim, Eun-Dong
    • Proceedings of the KIEE Conference
    • /
    • 2003.07c
    • /
    • pp.1559-1561
    • /
    • 2003
  • In northeast Asia, there will be several important HVDC transmission lines to be established in Korea and China for perspective electric network market. 5500V 4-inches High voltage thyristor can be used in the DC transmission and distribution of electric power system. In this application, many thyristors are connected in series for each thyristor valves. Therefore, the required low reverse-recovery charge QRR and low on-state voltage drop $V_{TM}$ for such thyristor is necessary to this application. In our work, the on-state and off-state voltage performance was simulated by commercial simulation software.

  • PDF

A Novel Integrated Battery Charger Structure for Multiple Charge and V2G application for Electric Vehicles (전기자동차의 다중충전 및 V2G 응용을 위한 새로운 통합 배터리 충전기구조)

  • Vu, Hai-Nam;Choi, Woojin
    • Proceedings of the KIPE Conference
    • /
    • 2016.11a
    • /
    • pp.13-14
    • /
    • 2016
  • This paper has introduces a novel Integrated On-board Charger (IOBC) to reduce the size, weight and cost of power conversion stages in Electric Vehicles (EVs). The IOBC is composed of an OBC and a low voltage dc-dc converter (LDC). The IOBC includes a bidirectional ac-dc converter and a bidirectional full-bridge converter with an active clamp circuit. The LDC converter is a hybrid topology combining an active clamped full-bridge converter and a forward converter derived from the Weinburg converter topology. Unlike conventional OBC, the proposed IOBC is compact and the LDC converter of it can achieve a higher efficiency. In addition, the LDC converter of the proposed IOBC can achieve high step-down voltage conversion ratio, no circulating current, no reverse recovery current of the rectifier diodes and small ripple current of output inductor on the auxiliary battery. A 1kW hardware of the LDC converter is implemented to verify the performances of the proposed IOBC.

  • PDF

Enhancement of Photocurrent Generation by C60-encapsulated Single-walled Carbon Nanotubes in Ru-sensitized Photoelectrochemical Cell

  • Lee, Jung-Woo;Park, Tae-Hee;Lee, Jong-Taek;Jang, Mi-Ra;Lee, Seung-Jin;Kim, Hee-Su;Han, Sung-Hwan;Yi, Whi-Kun
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.8
    • /
    • pp.2689-2693
    • /
    • 2012
  • Single-walled carbon nanotubes (SWNTs) and $C_{60}$-encapsulated SWNTs ($C_{60}@SWNTs$) are introduced to Ru-sensitized photoelectrochemical cells (PECs), and photocurrents are compared between two cells, i.e., an $RuL_2(NCS)_2$/DAPV/SWNTs/ITO cell and an $RuL_2(NCS)_2$/DAPV/$C_{60}@SWNTs$/ITO cell. [L = 2,2'-bipyridine-4,4'-dicarboxylic acid, DAPV = di-(3-aminopropyl)-viologen, and ITO = indium-tin oxide] The photocurrents are increased by 70.6% in the presence of $C_{60}@SWNTs$. To explain the photocurrent increase, the reverse-field emission method is used, i.e., $RuL_2(NCS)_2$/DAPV/SWNTs/ITO cell (or $RuL_2(NCS)_2$/DAPV/$C_{60}@SWNTs$/ITO cell) as an anode and a counter electrode Pt as a cathode in the external electric field. The improved field emission properties, i.e., ${\beta}$ (field enhancement factor) and emission currents in the reverse-field emission with $C_{60}@SWNTs$ indicate the enhancement of the PEC electric field, which implies the improvement of the electron transfer rate along with the reduced charge recombination in the cell.

New degradation mechanism of GaAs HBT induced by Hot carriers (핫 캐리어에 의한 GaAs HBT의 새로운 열화 메카니즘)

  • 권재훈;김도현;송정근
    • Journal of the Korean Institute of Telematics and Electronics D
    • /
    • v.34D no.11
    • /
    • pp.30-36
    • /
    • 1997
  • AlGaAs/GaAs HBTs are developed well enough to be commercialized as an active device in optical transmission system, but there remains the unanswered questions about reliability. In this paper we applied the reverse constant current stress at the high voltage in avalanche region for a long time to find out a new degradation mechanism of junctrion I-V. The unction off-set voltage at which the current vanishes to zero was shifted to the negative direction of applied bias due to the increment of leakage current as the stress time increases. It was identified that the degradation was induced by the hot carriers which were generated at space charge region and trapped at the interface between GaAs base and the passivation nitride enhancing the electric field across the nesa edge.

  • PDF

Concentration of Sodium Chloride, Sodium Acetate and Sodium Citrate Solutions by using Polyamide Reverse Osmosis Membrane (폴리아미드 역삼투막을 이용한 염화나트륨, 아세트산나트륨, 구연산나트륨 용액의 농축)

  • Lee, Heungil;Kim, In Ho
    • Korean Chemical Engineering Research
    • /
    • v.56 no.5
    • /
    • pp.679-686
    • /
    • 2018
  • Reverse osmosis (RO) concentration of sodium chloride, sodium acetate, and sodium citrate solutions has been performed by polyamide RO membrane. Concentration polarization phenomena was also studied by changing pressure, solute kinds, and initial solution concentration. Pressure effect on permeation flux was that the increase of flux was accompanied by the increase of pressure. Flux increase was observed by the decrease of initial solution concentration. Surface concentration on the RO membrane increases and so flux declines due to the concentration polarization. In the later phase of concentration, concentration polarization effect was decreased by the back diffusion of solute from the polariztion layer. In case of sodium citrate, its large ion size and charge density resulted in the discrepancy between theory and experimental data of concentration polarization. It may be due to electric repulsion on the membrane surface.

Efficiency Estimation for Desalination System of Seawater Using Reverse Osmosis Membrane (역삼투압막 해수담수화 장치의 미네럴 분리 성능평가)

  • Moon, Deok-Soo;Jung, Dong-Ho;Kim, Hyeon-Ju;Shin, Phil-Kwon
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.8 no.2
    • /
    • pp.60-66
    • /
    • 2005
  • When external pressure higher than osmosis pressure is reversely derived into solution, its solvent is moved into the solution having lower concentration, which is called 'reverse osmosis'. We investigated the desalination application of deep ocean water using reverse osmosis pressure of $40-70\;kgf/cm^2$ We observed how to operational factor j like flow rate, water temperature and pressure have effect on efficiency of reverse osmosis membrane and salts rejection. Fluxes of reverse osmosis membrane are directly proportional to water temperature and pressure. However, salts rejection rates are positively correlated with pressure and inversely proportional to water temperature. Separation efficiencies of osmosis membrane for major elements such as $Mg^{2+},\;Ca^{+2},\;Na^+\;and\;K^+$ are as follows in a strong electrolysis solution like seawater; $Ca^{2+},\;Mg^{2+}>K^+>Na^+$. Rejection rates of $Mg^{2+}\;and\;Ca^{2+}$ that have high electric charges are over 99% and show positively correlation with water temperature. Rejection rates of $Na^+$ having low electric charge is observed to be 98%-99%, which rates is much lower than those of $2^+$ charged ions like $Ca^{2+}\;and\;Mg^{2+}$. Ion rejection rates of boron, B, are much low because boron is present il free state or gas phase in seawater. Boron concentration in desalination water is over criteria of Korean drinking water, 0.3 mg/L. However, we could satisfied with the criteria of drinking water under the operation condition like temperature $5^{\circ}C$ and pressure $70kgf/cm^2$, using the relationship that rejection rates of boron is proportional to pressure and is inversely proportional to water temperature

  • PDF

Monovalent Ion Selective Anion-Exchange Membranes for Reverse Electrodialysis Application (역전기투석 응용을 위한 1가 이온 선택성 음이온교환막)

  • Ji-Hyeon Lee;Moon-Sung Kang
    • Membrane Journal
    • /
    • v.34 no.1
    • /
    • pp.58-69
    • /
    • 2024
  • Reverse electrodialysis (RED) is an electro-membrane process employing ion-exchange membranes (IEMs) that can harvest electric energy from the concentration difference between seawater and river water. Multivalent ions contained in seawater and river water bind strongly to the fixed charge groups of the IEM, causing high resistance and reducing open-circuit voltage and power density through uphill transport. In this study, a pore-filled anion-exchange membrane (PFAEM) with excellent monovalent ion selectivity and electrochemical properties was fabricated and characterized for RED application. The monovalent ion selectivity of the prepared membrane was 3.65, which was superior to a commercial membrane (ASE, Astom Corp.) with a selectivity of 1.27 under the same conditions. Additionally, the prepared membrane showed excellent electrochemical properties, including low electrical resistance compared to ASE. As a result of evaluating RED performance under seawater of 0.459 M NaCl/0.0510 M Na2SO4 and river water of 0.0153 M NaCl/0.0017 M Na2SO4, the maximum power density of 1.80 W/m2 was obtained by applying the prepared membrane, which is a 40.6% improved output performance compared to the ASE membrane.