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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Electrical Engineering and Technology
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The Korean Institute of Electrical Engineers
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Volume & Issues
Volume 10, Issue 6 - Nov 2015
Volume 10, Issue 5 - Sep 2015
Volume 10, Issue 4 - Jul 2015
Volume 10, Issue 3 - May 2015
Volume 10, Issue 2 - Mar 2015
Volume 10, Issue 1 - Jan 2015
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Optimal Coordination of Intermittent Distributed Generation with Probabilistic Power Flow
Xing, Haijun ; Cheng, Haozhong ; Zhang, Yi ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2211~2220
DOI : 10.5370/JEET.2015.10.6.2211
This paper analyzes multiple active management (AM) techniques of active distribution network (ADN), and proposes an optimal coordination model of intermittent distributed generation (IDG) accommodation considering the timing characteristic of load and IDG. The objective of the model is to maximize the daily amount of IDG accommodation under the uncertainties of IDG and load. Various active management techniques such as IDG curtailment, on-load tap changer (OLTC) tap adjusting, voltage regulator (VR) tap adjusting, shunt capacitors compensation and so on are fully considered. Genetic algorithm and Primal-Dual Interior Point Method (PDIPM) is used for the model solving. Point estimate method is used to simulate the uncertainties. Different scenarios are selected for the IDG accommodation capability investigation under different active management schemes. Finally a modified IEEE 123 case is used to testify the proposed accommodation model, the results show that the active management can largely increase the IDG accommodation and penetration.
Stepwise Inertial Control of a Doubly-Fed Induction Generator to Prevent a Second Frequency Dip
Kang, Mose ; Lee, Jinsik ; Hur, Kyeon ; Park, Sang Ho ; Choy, Youngdo ; Kang, Yong Cheol ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2221~2227
DOI : 10.5370/JEET.2015.10.6.2221
To arrest a frequency nadir, a stepwise inertial control (SIC) scheme generates a constant active power reference signal of a wind turbine generator (WTG) immediately after a disturbance and maintains it for the predetermined time. From that point, however, the reference of a WTG abruptly decreases to restore the rotor speed for the predefined period. The abrupt decrease of WTG output power will inevitably cause a second frequency dip. In this paper, we propose a modified SIC scheme of a doubly-fed induction generator (DFIG) that can prevent a second frequency dip. A reference value of the modified SIC scheme consists of a reference for the maximum power point tracking control and a constant value. The former is set to be proportional to the cube of the rotor speed; the latter is determined so that the rotor speed does not reach the minimum operating limit by considering the mechanical power curve of a DFIG. The performance of the modified SIC was investigated for a 100 MW aggregated DFIG-based wind power plant under various wind conditions using an EMTP-RV simulator. The results show that the proposed SIC scheme significantly increases the frequency nadir without causing a second frequency dip.
Integrated Generation and Transmission Expansion Planning Using Generalized Bender’s Decomposition Method
Kim, Hyoungtae ; Lee, Sungwoo ; Kim, Wook ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2228~2239
DOI : 10.5370/JEET.2015.10.6.2228
A novel integrated optimization method based on the Generalized Bender’s Decomposition (GBD) is proposed to combine both generation and transmission expansion problems. Most of existing researches on the integrated expansion planning based on the GBD theory incorporate DC power flow model to guarantee the convergence and improve the computation time. Inherently the GBD algorithm based on DC power flow model cannot consider variables and constraints related bus voltages and reactive power. In this paper, an integrated optimization method using the GBD algorithm based on a linearized AC power flow model is proposed to resolve aforementioned drawback. The proposed method has been successfully applied to Garver’s six-bus system and the IEEE 30-bus system which are frequently used power systems for transmission expansion planning studies.
Investigation and Simulation Study on the Cascading Trip-off Fault of a Large Number of Wind Turbines in China on May 14, 2012
Qiao, Ying ; Lu, Zong-Xiang ; Lu, Ji ; Ruan, Jia-Yang ; Wu, Lin-lin ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2240~2248
DOI : 10.5370/JEET.2015.10.6.2240
The integration of the large-scale wind power brings great challenge to the stability of the power grid. This paper investigates and studies the fault on May 14, 2012 of the large-scale cascading trip-off of wind turbines in North China. According to the characteristics of the voltage variation, the fault process is divided into three stages: the pre-event stage, the critical stage before cascading, and the cascading stage. The scenes in the fault are reproduced, using the full-size actual power system model. Simulation models of double-fed induction generators (DFIGs) and SVCs including protection settings and controller strategies are carefully chosen to find out the reason of voltage instability in each stage. Some voltage dynamic that have never been observed before in the faults of the same kind are analyzed in detail, and an equivalent voltage sensitive dynamic model of DFIG is proposed for the fast computation. The conclusions about the voltage dynamics are validated by the actual PMU observation evidence.
Dynamic Reference-based Voltage Droop Control for VSC-MTDC System
Kim, Nam-Dae ; Kim, Hak-Man ; Park, Jae-Sae ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2249~2255
DOI : 10.5370/JEET.2015.10.6.2249
The use of voltage source converter multi-terminal direct current (VSC-MTDC) systems is anticipated to increase from the introduction of wind farms and super grids in the near future. Effective control of the DC voltage in VSC-MTDC systems is an important research topic. This paper proposes a new dynamic reference-based voltage droop control to control the DC voltage in VSC-MTDC systems more effectively. The main merit of the dynamic reference-based voltage droop control is that it can reduce the steady-state error in conventional voltage droop control by changing references according to the system operating conditions. The performance of the proposed control was tested in a hardware-in-the-loop simulation (HILS) system based on the OPAL-RT real-time digital simulator and four digital signal processing boards.
Application of SFCL on Bus Tie for Parallel Operation of Power Main Transformers in a Fuel Cell Power Systems
Chai, Hui-Seok ; Kang, Byoung-Wook ; Kim, Jin-Seok ; Kim, Jae-Chul ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2256~2261
DOI : 10.5370/JEET.2015.10.6.2256
In the power plant using high temperature fuel cells such as Molten Carbonate Fuel Cell(MCFC), and Solid Oxide Fuel Cell(SOFC), the generated electric power per area of power generation facilities is much higher than any other renewable energy sources. - High temperature fuel cell systems are capable of operating at MW rated power output. - It also has a feature that is short for length of the line for connecting the interior of the generation facilities. In normal condition, these points are advantages for voltage drops or power losses. However, in abnormal condition such as fault occurrence in electrical system, the fault currents are increased, because of the small impedance of the short length of power cable. Commonly, to minimize the thermal-mechanical stresses on the stack and increase the systems reliability, we divided the power plant configuration to several banks for parallel operation. However, when a fault occurs in the parallel operation system of power main transformer, the fault currents might exceed the interruption capacity of protective devices. In fact, although the internal voltage level of the fuel cell power plant is the voltage level of distribution systems, we should install the circuit breakers for transmission systems due to fault current. To resolve these problems, the SFCL has been studied as one of the noticeable devices. Therefore, we analyzed the effect of application of the SFCL on bus tie in a fuel cell power plants system using PSCAD/EMTDC.
Off-Line Parameter Identification of Permanent Magnet Synchronous Motor Using a Goertzel Algorithm
Yoon, Jae-Seung ; Lee, Kyoung-Gu ; Lee, June-Seok ; Lee, Kyo-Beum ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2262~2270
DOI : 10.5370/JEET.2015.10.6.2262
Generally, internal parameters of the motors and generators can be divided to the resistance and inductance components. They can become a cause of the changing internal parameters because they have sensitive characteristics due to external conditions. The changed parameters can generate the outputs which include error values from the speed and current controllers. Also, it can bring the temperature increase and mechanical damage to the system. Therefore, internal parameters of the motors and generators need to obtain their values according to the external conditions because it can prevent the mechanical damage caused by the changed parameters. In this paper, the off-line parameter identification method is verified using the Goertzel algorithm. The motor used in the simulation and experiments is an interior permanent magnet synchronous motor (IPMSM), and the proposed algorithm is verified by the simulation and experimental results.
Optimal Design of a MW Class SCSG for a Tidal Current Power Generation System
Go, Byeong-Soo ; Sung, Hae-Jin ; Park, Minwon ; Yu, In-Keun ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2271~2276
DOI : 10.5370/JEET.2015.10.6.2271
A superconducting synchronous generator (SCSG) can be expected to decrease the size and weight compared to conventional tidal current generators. This paper proposes an optimal design of a 2 MW class SCSG for a tidal current power generation system. The proposed optimal design of the SCSG will reduce the length of the high-temperature superconducting wire as well as the weight and volume of the SCSG. The 3D finite element method is used to analyze the magnetic field distribution. The optimized 2 MW SCSG is compared with a 2 MW conventional generator. As the optimized SCSG is more compact and lighter than a conventional generator, it will be efficiently applied to practical tidal power systems.
Identification of Open-Switch and Short-Switch Failure of Multilevel Inverters through DWT and ANN Approach using LabVIEW
Parimalasundar, E. ; Vanitha, N. Suthanthira ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2277~2287
DOI : 10.5370/JEET.2015.10.6.2277
In recent times, multilevel inverters are given high priority in many large industrial drive applications. However, the reliability of multilevel inverters are mainly affected by the failure of power electronic switches. In this paper, open-switch and short-switch failure of multilevel inverters and its identification using a high performance diagnostic system is discussed. Experimental and simulation studies were carried out on five level cascaded H-Bridge multilevel inverter and its output voltage waveforms were analyzed at different switch fault cases and at different modulation index values. Salient frequency domain features of the output voltage signal were extracted using the discrete wavelet transform multi resolution signal decomposition technique. Real time application of the proposed fault diagnostic system was implemented through the LabVIEW software. Artificial neural network was trained offline using the Matlab software and the resultant network parameters were transferred to LabVIEW real time system. In the proposed system, it is possible to precisely identify the individual faulty switch (may be due to open-switch (or) short-switch failure) of multilevel inverters.
Systematic Dynamic Modeling of an Integrated Single-stage Power Converter
Choi, Ki-Young ; Lee, Kui-Jun ; Kim, Yong-Wook ; Kim, Rae-Young ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2288~2296
DOI : 10.5370/JEET.2015.10.6.2288
This paper proposes a novel systematic modeling approach for an integrated single-stage power converter in order to predict its dynamic characteristics. The basic strategy of the proposed modeling is substituting the internal converters with an equivalent current source, and then deriving the dynamic equations under a standalone operation using the state-space averaging technique. The proposed approach provides an intuitive modeling solution and simplified mathematical process with accurate dynamic prediction. The simulation and experimental results by using an integrated boost-flyback converter prototype provide verification consistent with theoretical expectations.
Design and Implementation of a Reverse Matrix Converter for Permanent Magnet Synchronous Motor Drives
Lee, Eunsil ; Lee, Kyo-Beum ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2297~2306
DOI : 10.5370/JEET.2015.10.6.2297
This paper presents the development of a system with a reverse matrix converter (RMC) for permanent magnet synchronous motor (PMSM) drive and its effective control method. The voltage transfer ratio of the general matrix converter is restricted to a maximum value of 0.866, which is not suitable for applications whose source voltages are lower than the load voltages. The proposed RMC topology can step up the voltage without any additional components in the conventional circuit. Its control method is different from traditional matrix converter’s one, thus this paper proposes control schemes of RMC by means of controlling both the generator and motor side currents with properly designed control loop. The converter can have sinusoidal input/output current waveforms in steady state condition as well as a boosted voltage. In this paper, a hardware system with an RMC for a PMSM drive system is described. The performance of the system was investigated through experiments
DCM Frequency Control Algorithm for Multi-Phase DC-DC Boost Converters for Input Current Ripple Reduction
Joo, Dong-Myoung ; Kim, Dong-Hee ; Lee, Byoung-Kuk ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2307~2314
DOI : 10.5370/JEET.2015.10.6.2307
In this paper, a discontinuous conduction mode (DCM) frequency control algorithm is proposed to reduce the input current ripple of a multi-phase interleaved boost converter. Unlike conventional variable duty and constant frequency control, the proposed algorithm controls the switching frequency to regulate the output voltage. By fixing the duty ratio at 1/N in the N-phase interleaved boost converter, the input current ripple can be minimized by ripple cancellation. Furthermore, the negative effects of the diode reverse recovery current are eliminated because of the DCM characteristic. A frequency controller is designed to employ the proposed algorithm considering the magnetic permeability change. The proposed algorithm is analyzed in the frequency domain and verified by a 600 W three-phase boost converter prototype that achieved 57% ripple current reduction.
On the Detection of Induction-Motor Rotor Fault by the Combined “Time Synchronous Averaging-Discrete Wavelet Transform” Approach
Ngote, Nabil ; Ouassaid, Mohammed ; Guedira, Said ; Cherkaoui, Mohamed ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2315~2325
DOI : 10.5370/JEET.2015.10.6.2315
Induction motors are widely used in industrial processes since they offer a very high degree of reliability. But like any other machine, they are vulnerable to faults, which if left unmonitored, might lead to an unexpected interruption at the industrial plant. Therefore, the condition monitoring of the induction motors have been a challenging topic for many electrical machine researchers. Indeed, the effectiveness of the fault diagnosis and prognosis techniques depends very much on the quality of the fault features selection. However, in induction-motor drives, rotor defects are the most complex in terms of detection since they interact with the supply frequency within a restricted band around this frequency, especially in the no-loaded case. To overcome this drawback, this paper deals with an efficient and new method to diagnose the induction-motor rotor fault based on the digital implementation of the monitoring algorithm based on the association of the Time Synchronous Averaging technique and Discrete Wavelet Transform. Experimental results are presented in order to show the effectiveness of the proposed method. The obtained results are largely satisfactory, indicating a promising industrial application of the combined “Time Synchronous Averaging – Discrete Wavelet Transform” approach.
A Fault Severity Index for Stator Winding Faults Detection in Vector Controlled PM Synchronous Motor
Hadef, M. ; Djerdir, A. ; Ikhlef, N. ; Mekideche, M.R. ; N`diaye, A. O. ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2326~2333
DOI : 10.5370/JEET.2015.10.6.2326
Stator turn faults in permanent magnet synchronous motors (PMSMs) are more dangerous than those in induction motors (IMs) because of the presence of spinning rotor magnets that can be turned off at will. Condition monitoring and fault detection and diagnosis of the PMSM have been receiving a growing amount of attention among scientists and engineers in the past few years. The aim of this study is to propose a new detection technique of stator winding faults in a three-phase PMSM. This technique is based on the image analysis and recognition of the stator current Concordia patterns, and will allow the identification of turn faults in the stator winding as well as its correspondent fault index severity. A test bench of a vector controlled PMSM motor behaviors under short circuited turn in two phases stator windings has been built. Some experimental results of the phase to phase short circuits have been performed for diagnosis purpose.
A Low-Cost Digital PWM-Controlled LED Driver with PFC and Low Light Flicker
Li, Yi ; Lim, Jae-Woo ; Kim, Hee-Jun ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2334~2342
DOI : 10.5370/JEET.2015.10.6.2334
This paper proposes an LED driving circuit with a digital controller, power factor correct (PFC) function, and low light flicker. The key topology of the proposed circuit is a conventional Flyback combined with a pre-stage. As a result, there will be less light flicker than with other one-stage PFC circuits. A digital controller, implemented using a low-cost microcontroller, dsPIC30F2020, will meet PFC and low light flicker. The experimental results validate the functionality of the proposed circuit.
Titanium Dioxide Sol-gel Schottky Diodes and Effect of Titanium Dioxide Nanoparticle
Maniruzzaman, Mohammad ; Zhai, Lindong ; Mun, Seongcheol ; Kim, Jaehwan ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2343~2347
DOI : 10.5370/JEET.2015.10.6.2343
This paper reports the effect of Titanium dioxide (TiO
) nanoparticles on a TiO
sol-gel Schottky diode. TiO
nanoparticles were blended with TiO
sol-gel to fabricate the Schottky diode. TiO
nanoparticles showed strong anatase and rutile X-ray diffraction peaks. However, the mixture of TiO
sol-gel and TiO
nanoparticles exhibited no anatase and rutile peaks. The forward current of the Schottky diode drastically increased as the concentration of TiO
nanoparticles increased up to 10 wt. % and decreased after that. The possible conduction mechanism is more likely space charge limited conduction.
Investigations on Eco Friendly Insulating Fluids from Rapeseed and Pongamia Pinnata Oils for Power Transformer Applications
Thanigaiselvan, R. ; Raja, T. Sree Renga ; Karthik, R. ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2348~2355
DOI : 10.5370/JEET.2015.10.6.2348
Transformer mineral oil which is normally hydrocarbon based is non- biodegradable and pollutes the environment in all aspects. Though vegetable oils are eco-friendly in nature and potentially could be used in transformers as a replacement for the mineral oil, there usage is restricted because of their oxidative instability. The present work focuses on using rapeseed oil and pongamia (pongamia pinnata) oil as effective alternatives for the traditional mineral oil in power transformer. The oxidative stability of the rapeseed oil and pongamia oil is increased by using combinations of the natural and synthetic anti-oxidants as additives. The parameters like breakdown voltage, viscosity, flash point, fire point are measured for the rapeseed oil and pongamia oil with and without the additives as per IEC and ASTM standards. The results shown encouraging changes in the parameter values and ensures the use of the oils as a potential alternative insulation in power transformers.
A New Optimized Localized Technique of CG Return Stroke Lightning Channel in Forest
Kabir, Homayun ; Kanesan, Jeevan ; Reza, Ahmed Wasif ; Ramiah, Harikrishnan ; Dimyati, Kaharudin ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2356~2363
DOI : 10.5370/JEET.2015.10.6.2356
Localization of lightning strike point (LSP) in the forest is modeled to mitigate the forest fire damage. Though forest fire ignited by lightning rarely happens, its damage on the forest is grievousness. Therefore, predicting accurate location of LSP becomes crucial in order to control the forest fire. In this paper, we proposed a new hybrid localization algorithm by combining the received signal strength (RSS) and the received signal strength ratio (RSSR) to improve the accuracy by mitigating the environmental effect of lightning strike location in the forest. The proposed hybrid algorithm employs antenna theory (AT) model of cloud-to-ground (CG) return stroke lightning channel to forecast the location of the lightning strike. The obtained results show that the proposed hybrid algorithm achieves better location accuracy compared to the existing RSS method for predicting the lightning strike location considering additive white Gaussian noise (AWGN) environment.
Structural and Electrical Properties of an Electrolyte-insulator-metal Device with Variations in the Surface Area of the Anodic Aluminum Oxide Template for pH Sensors
Kim, Yong-Jun ; Lee, Sung-Gap ; Yeo, Jin-Ho ; Jo, Ye-Won ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2364~2367
DOI : 10.5370/JEET.2015.10.6.2364
In this study, we fabricated an electrolyte-insulator-metal (EIM) device incorporating a high-k Al
sensing membrane using a porous anodic aluminum oxide (AAO) through a two-step anodizing process for pH detection. The structural properties were observed by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction patterns (XRD). Electrochemical measurements taken consisted of capacitance-voltage (C-V), hysteresis voltage and drift rates. The average pore diameter and depth of the AAO membrane with a pore-widening time of 20 min were 123nm and 273.5nm, respectively. At a pore-widening time of 20 min, the EIM device using anodic aluminum oxide exhibited a high sensitivity (56mV/pH), hysteresis voltage (6.2mV) and drift rate (0.25mV/pH).
Experimental Study on Modifiable Walking Pattern Generation for Handling Infeasible Navigational Commands
Hong, Young-Dae ; Lee, Bumjoo ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2368~2375
DOI : 10.5370/JEET.2015.10.6.2368
To accommodate various navigational commands, a humanoid should be able to change its walking motion in real time. Using the modifiable walking pattern generation (MWPG) algorithm, a humanoid can handle dynamic walking commands by changing its walking period, step length, and direction independently. If the humanoid is given a command to perform an infeasible movement, the algorithm substitutes the infeasible command with a feasible one using binary search. The feasible navigational command is subsequently translated into the desired center-of-mass (CM) state. Every sample time CM reference is generated using a zero-moment-point (ZMP) variation scheme. Based on this algorithm, various complex walking patterns can be generated, including backward and sideways walking, without detailed consideration of the feasibility of the navigational commands. In a previous study, the effectiveness of the MWPG algorithm was verified by dynamic simulation. This paper presents experimental results obtained using the small-sized humanoid robot platform DARwIn-OP.
Design and Evaluation of the Unmanned Technology Research Center Exoskeleton Implementing the Precedence Walking Assistance Mechanism
Cha, Dowan ; Oh, Sung Nam ; Lee, Hee Hwan ; Kim, Kyung-Soo ; Kim, Kab Il ; Kim, Soohyun ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2376~2383
DOI : 10.5370/JEET.2015.10.6.2376
Assistance of the operator’s walking ability while carrying a load is a challenging area in lower limb exoskeletons. We implement an exoskeleton called the Unmanned Technology Research Center Exoskeleton (UTRCEXO), which enables the operator to walk with a load more comfortably. The UTRCEXO makes use of two types of DC motor to assist the hip and knee joints. The UTRCEXO detects the operator’s walking intention including step initiation with insole-type FSRs faster without using any bio-signals and precedes the operator’s step with a reference torque. It not only reduces interaction forces between the operator and the UTRCEXO, but also allows the operator to walk with a load more comfortably. In this paper, we present the UTRCEXO implementing the walking assistance mechanism with interaction force reduction during walking.
New Medical Image Fusion Approach with Coding Based on SCD in Wireless Sensor Network
Zhang, De-gan ; Wang, Xiang ; Song, Xiao-dong ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2384~2392
DOI : 10.5370/JEET.2015.10.6.2384
The technical development and practical applications of big-data for health is one hot topic under the banner of big-data. Big-data medical image fusion is one of key problems. A new fusion approach with coding based on Spherical Coordinate Domain (SCD) in Wireless Sensor Network (WSN) for big-data medical image is proposed in this paper. In this approach, the three high-frequency coefficients in wavelet domain of medical image are pre-processed. This pre-processing strategy can reduce the redundant ratio of big-data medical image. Firstly, the high-frequency coefficients are transformed to the spherical coordinate domain to reduce the correlation in the same scale. Then, a multi-scale model product (MSMP) is used to control the shrinkage function so as to make the small wavelet coefficients and some noise removed. The high-frequency parts in spherical coordinate domain are coded by improved SPIHT algorithm. Finally, based on the multi-scale edge of medical image, it can be fused and reconstructed. Experimental results indicate the novel approach is effective and very useful for transmission of big-data medical image(especially, in the wireless environment).
Multiple Faults Detection and Isolation via Decentralized Sliding Mode Observer for Reconfigurable Manipulator
Zhao, Bo ; Li, Chenghao ; Ma, Tianhao ; Li, Yuanchun ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2393~2405
DOI : 10.5370/JEET.2015.10.6.2393
This paper considers a decentralized multiple faults detection and isolation (FDI) scheme for reconfigurable manipulators. Inspired by their modularization property, a global sliding mode (GSM) based stable adaptive fuzzy decentralized controller is investigated for the system in fault free, while for the system suffering from multiple faults (actuator fault and sensor fault), the decentralized sliding mode observer (DSMO) is employed to detect their occurrence. Hereafter, the time and location of faults can be determined by a fault isolation scheme via a bank of DSMOs. Finally, the effectiveness of the proposed schemes in controlling, detecting and isolating faults is illustrated by the simulations of two 3-DOF reconfigurable manipulators with different configurations successfully.
Multi-Parameter Based Scheduling for Multi-user MIMO Systems
Chanthirasekaran, K. ; Bhagyaveni, M.A. ; Parvathy, L. Rama ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2406~2412
DOI : 10.5370/JEET.2015.10.6.2406
Multi-user multi-input multi-output (MU-MIMO) system has attracted the 4
generation wireless network as one of core technique for performance enrichment. In this system rate control is a challenging problem and another problem is optimization. Proper scheduling can resolve these problems by deciding which set of user and at which rate the users send their data. This paper proposes a new multi-parameter based scheduling (MPS) for downlink multi-user multiple-input multiple-output (MU-MIMO) system under space-time block coding (STBC) transmissions. Goal of this MPS scheme is to offer improved link level performance in terms of a low average bit error rate (BER), high packet delivery ratio (PDR) with improved resource utilization and service fairness among the user. This scheme allows the set of users to send data based on their channel quality and their demand rates. Simulation compares the MPS performance with other scheduling scheme such as fair scheduling (FS), normalized priority scheduling (NPS) and threshold based fair scheduling (TFS). The results obtained prove that MPS has significant improvement in average BER performance with improved resource utilization and fairness as compared to the other scheduling scheme.
Core muscle Strengthening Effect During Spine Stabilization Exercise
Han, Kap-Soo ; Nam, Hyun Do ; Kim, Kyungho ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2413~2419
DOI : 10.5370/JEET.2015.10.6.2413
Core spinal muscles are related to trunk stability and assume the main role of stabilizing the spine during daily activities; strengthening of core muscles around the spine can therefore reduce the chance of back pain. The objective of the study was to investigate the effect of core muscle strengthening in the spine during spine stabilization exercise using a whole body tilt device. To achieve this, a validated musculoskeletal (MS) model of the whole body was used to replicate the input motion from the whole body tilting exercise. An inverse dynamics analysis was executed to estimate spine loads and muscle forces depending on the tilting angles of the exercise device. The activation of long and superficial back muscles such as the erector spinae (iliocostalis and longissimus) were mainly affected by the forward direction (-40°) of the tilt, while the front muscles (psoas major, quadratus lumborum, and external and internal obliques) were mainly affected by the backward tilting direction (40°). Deep muscles such as the multifidi and short muscles were activated in most directions of the rotation and tilt. The backward directions of the tilt using this device could be carefully applied for the elderly and for rehabilitation patients who are expected to have less muscle strength. In this study, it was shown that the spine stabilization exercise device can provide considerable muscle exercise effect.
An Evolutionary Optimization Approach for Optimal Hopping of Humanoid Robots
Hong, Young-Dae ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2420~2426
DOI : 10.5370/JEET.2015.10.6.2420
This paper proposes an evolutionary optimization approach for optimal hopping of humanoid robots. In the proposed approach, the hopping trajectory is generated by a central pattern generator (CPG). The CPG is one of the biologically inspired approaches, and it generates rhythmic signals by using neural oscillators. During the hopping motion, the disturbance caused by the ground reaction forces is compensated for by utilizing the sensory feedback in the CPG. Posture control is essential for a stable hopping motion. A posture controller is utilized to maintain the balance of the humanoid robot while hopping. In addition, a compliance controller using a virtual spring-damper model is applied for stable landing. For optimal hopping, the optimization of the hopping motion is formulated as a minimization problem with equality constraints. To solve this problem, two-phase evolutionary programming is employed. The proposed approach is verified through computer simulations using a simulated model of the small-sized humanoid robot platform DARwIn-OP.
Observer-based Feedback Controller Design for Robust Tracking of Discrete-time Polytopic Uncertain LTI Systems
Oh, Sangrok ; Kim, Jung-Su ; Shim, Hyungbo ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2427~2433
This paper presents an observer-based robust controller for constant reference tracking of linear time invariant systems with polytopic model uncertainties. To this end, this paper not only designs a robust integral controller gain but also suggests how to determine the robust observer gain and the observer model used in the observer. Since the observer model selection is not obvious due to the polytopic uncertainties, particular attention needs to be paid to that. This paper computes the robust controller and observer gains first. Then, the observer model is selected in a way that the whole closedloop is stable and LMIs are used in the middle of choosing the gains and observer model. Simulation examples show that the proposed observer-based feedback control successfully achieves robust reference tracking.
Individualized Exercise and Diet Recommendations: An Expert System for Monitoring Physical Activity and Lifestyle Interventions in Obesity
Nam, Yunyoung ; Kim, Yeesock ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2434~2441
DOI : 10.5370/JEET.2015.10.6.2434
This paper proposes an exercise recommendation system for treating obesity that provides systematic recommendations for exercise and diet. Five body indices are considered as indicators for recommend exercise and diet. The system also informs users of prohibited foods using health data including blood pressure, blood sugar, and total cholesterol. To maximize the utility of the system, it displays recommendations for both indoor and outdoor activities. The system is equipped with multimode sensors, including a three-axis accelerometer, a laser, a pressure sensor, and a wrist-mounted sensor. To demonstrate the effectiveness of the system, field tests are carried out with three participants over 20 days, which show that the proposed system is effective in treating obesity.
Advanced Railway Power Quality Detecting Algorithm Using a Combined TEO and STFT Method
Yoo, Je-Ho ; Shin, Seung-Kwon ; Park, Jong-young ; Cho, Soo-Hwan ;
Journal of Electrical Engineering and Technology, volume 10, issue 6, 2015, Pages 2442~2447
DOI : 10.5370/JEET.2015.10.6.2442
Because an electric railway vehicle is a large scale moving load, it can cause various kinds of power quality problems in the railroad power system. The power quality impacts are considered as the strong instantaneous stresses to the related power systems and can cause an accelerating aging and a malfunction of the power supplying components. Therefore, it is necessary to detect the small and intermittent symptoms mixed in the voltage waveform. However, they cannot be detected by the triggering functions of the existing power analyzers installed in the railway systems. This paper will examine the drawback of some fast detection tools and propose an advanced detecting and analyzing method based on a combined TEO and STFT algorithm.