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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Transactions of The Korean Institute of Electrical Engineers
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The Korean Institute of Electrical Engineers
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Volume & Issues
Volume 57, Issue 12 - Dec 2008
Volume 57, Issue 11 - Nov 2008
Volume 57, Issue 10 - Oct 2008
Volume 57, Issue 9 - Sep 2008
Volume 57, Issue 8 - Aug 2008
Volume 57, Issue 7 - Jul 2008
Volume 57, Issue 6 - Jun 2008
Volume 57, Issue 5 - May 2008
Volume 57, Issue 4 - Apr 2008
Volume 57, Issue 3 - Mar 2008
Volume 57, Issue 2 - Feb 2008
Volume 57, Issue 1 - Jan 2008
Selecting the target year
Implementation of Out-of-Step Detection Algorithm based on Multi-Agent System using EMTP-MODELS
Lee, Byung-Hyun ; Yeo, Sang-Min ; Lee, You-Jin ; Sung, No-Kyu ; Kim, Chul-Hwan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 537~542
The protection against transient instability and consequent out-of-step condition is a major concern for the utility industry. Unstable system may cause serious damage to system elements such as generators and transmission lines. Therefore, out-of-step detection is essential to operate a system safely. Also, a multi-agent system is one that consists of a number of agents, which interact with one another. Multi-agent systems(MAS) can offer the flexibility and the adaptability to the previous algorithm. In this paper, the detection algorithm of out-of-step is designed by multi-agent system and implemented by EMTP-MODELS. To verify performance of the proposed algorithm based on multi-agent system, simulations by EMTP have been carried out.
A Study on Voltage and Reactive Power Control Methodology using Integer Programming and Local Subsystem
Kim, Tae-Kyun ; Choi, Yun-Hyuk ; Seo, Sang-Soo ; Lee, Byong-Jun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 543~550
This paper proposes an voltage and reactive power control methodology, which is motivated towards implementation in the korea power system. The main voltage control devices are capacitor banks, reactor banks and LTC transformers. Effects of control devices are evaluated by local subsystem's cost computations. This local subsystem is decided by 'Tier' and 'Electrical distance' in the whole system. The control objective at present is to keep the voltage profile within constraints with minimum switching cost. A robust control strategy is proposed to make the control feasible and optimal for a set of power-flow cases that may occur important event from system. This studies conducted for IEEE 39-bus low and high voltage contingency cases indicate that the proposed control methodology is much more effective than PSS/E simulation tool in deciding switching of capacitor and reactor banks.
Selection of Optimal Location and Size of Distributed Generation Considering Power Loss
Lee, Soo-Hyoung ; Park, Jung-Wook ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 551~559
Increase in power consumption can cause a serious stability problem of an electric power system without construction of new power plants or transmission lines. Also, it can generate large power loss of the system. In costly and environmentally effective manner to avoid constructing the new infrastructures such as power plants and transmission lines, etc, the distributed generation(DG) has paid great attentions so far as a solution for the above problem. Selection of optimal location and size of the DG is the necessary process to maintain the stability and reliability of existing system effectively. However, the systematic and cardinal rule for this issue is still open question. In this paper, the method to determine optimal location of the DG is proposed by considering power loss when the DG is connected to an electric power grid. Also, optimal size of not only the corresponding single DG but also the multi-DGs is determined with the proposed systematic approach. The IEEE benchmark 30-bus test system is analyzed to evaluate the feasibility and effectiveness of the proposed method.
Optimal Transmission Expansion Planning Considering the Uncertainties of Power Market
Son, Min-Kyun ; Kim, Jin-O ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 560~566
Today, as the power trades between generation companies and power customer are liberalized, the uncertainty level of operated power system is rapidly increased. Therefore, transmission operators as decision makers for transmission expansion are required to establish a deliberate investment plan for effective operations of transmission facilities considering forecasted conditions of power system. This paper proposes the methodology for the optimal solution of transmission expansion in deregulated power system. The paper obtains the expected value of transmission congestion cost for various scenarios by using occurrence probability. In addition, the paper assumes that increasing rates of loads are the probability distribution and indicates the location of expanded transmission line, the time for transmission expansion with the minimum cost for the future by performing the Montecarlo simulation. To minimize the investment risk as the variance of the congestion cost, Mean-Variance Markowitz portfolio theory is applied to the optimization model by the penalty factor of the variance. By the case study, the optimal solution for transmission expansion plan considering the feature of market participants is obtained.
A New Stabilizing Method for Transiently Unstable Systems by Using Transient Energy Function
Kim, Jung-Woo ; Chun, Yeong-Han ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 567~575
Transient security assessment(TSA) is becoming an essential requirement not only for security monitoring but also for stabilizing control of power systems under new electricity environments. It has already been pointed out that fast transient stability study is an important part for monitoring and controlling system security. In this paper, we discuss an energy function method for stabilizing control of transiently unstable systems by introducing generator tripping system to enhance the transient stability of power systems. The stabilization with less tripped power can be obtained by tripping the generators faster than out-of-synchronism relay. Fast transient stability assessment based on the state estimation and direct transient energy function method is an important part of the stabilizing scheme. It is possible to stabilize the transiently unstable system by tripping less generators before the action of out-of-synchronism relay, especially when a group of generator are going to be out-of-synchronism. Moreover, the amount of generator output needed for tripping can be decided by Transient Energy Function(TEF) method. The main contribution of this paper is on the stabilizing scheme which can be running in the Wide Area Control System.
Transmission Cost Allocation Considering Reliability Cost
Park, Yeong-Hyeon ; Kim, Dong-Min ; Kim, Jin-O ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 576~581
Electricity Market in Korea can't provide locational price signal through energy price because energy market is CBP(Cost Based Pool) using uniform price. Generators don't want to locate in a densely populated load area(like the metropolitan area). Because they are paid more fixed cost in metropolitan area. This situation has loss and congestion occurred in power system. However energy market without price signal can't lead generator to the metropolitan. So, market participants should be provided price signal through the transmission price instead of energy price. This paper proposes transmission pricing method considering reliability cost in order to offer price signal. Also, it proposes the method to allocate the transmission cost to each transmission line user through a fair and a reasonable manner. The transmission price is decided by the reliability value of each line. If a transmission line of high reliability value is broke, users using that line will get a loss and a discomfort. So, it is fair that users using a transmission line of high reliability value pay more than the other users. Also, it is reasonable that a transmission line owner get paid more form users using that line.
Power Control Methods for Microgrid with Multiple Distributed Generators
Chung, Il-Yop ; Won, Dong-Jun ; Moon, Seung-Il ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 582~588
Microgrids are new distribution level power networks that consist of various electronically-interlaced generators and sensitive loads. The important control object of Microgrids is to supply reliable and high-quality power even during the faults or loss of mains(islanding) cases. This paper presents power control methods to coordinate multiple distributed generators(DGs) against abnormal cases such as islanding and load power variations. Using speed-droop and voltage-droop characteristics, multiple distributed generators can share the load power based on locally measured signals without any communications between them. This paper adopts the droop controllers for multiple DG control and improved them by considering the generation speed of distribution level generators. Dynamic response of the proposed control scheme has been investigated under severe operation cases such as islanding and abrupt load changes through PSCAD/EMTDC simulations.
Optimal Design of a PMLSM with 9 Pole 10 Slot for Detent Force Reduction
Hwang, In-Sung ; Yoon, Hee-Sung ; Koh, Chang-Seop ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 589~595
Detent force of a permanent magnet linear motor(PMLSM) consist of cogging and drag forces, and should be minimized for high precision control purpose applications. This paper shows that the cogging force can be reduced effectively by employing 9 pole 10 slot structure. The drag force is minimized by optimizing the total length and shape of the exterior teeth of armature core simultaneously by using(
) evolution strategy coupled with response surface method. After optimization, the optimized PMLSM is proven to reduce 95% and 92.6% of the cogging and total detent forces, respectively, and give 12% and 6.4% higher Back-emf and thrust force, respectively, compared with a conventional 12 pole 9 slot structure under the same condition. Additionally, Simulation results by the proposed optimum design are verified by the experiment results.
The Study of Dynamic Characteristic of PMLSM According to Variable Load
Lee, Seung-Hoon ; Jang, Ki-Bong ; Kim, Gyu-Tak ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 596~602
This paper presents the dynamic characteristic analysis of Permanent Magnet Linear Synchronous Motor(PMLSM) according to variable load. In order to analyze dynamic characteristics, finite element method(FEM) was used for calculation of the parameter and the Matlab simulink was used for dynamic characteristic simulation. The measuring system of the dynamic characteristics was manufactured and the experiment results were compared with the simulation results.
Design and Characteristics Investigation of Air-core Tubular Linear BLDC Motor
Moon, Ji-Woo ; Cho, Yun-Hyun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 603~609
Slotless linear brushless DC motor are widely used in precision machine applications because of their advantages such as low of detent force, negligible iron loss. But they have a disadvantage such as low thrust density, thrust ripple, and excessive use of permanent magnet materials. These lead to undesirable performance and high production cost. In this paper, we deal with the design and characteristics investigation of a air-core tubular linear brushless DC(TLBLDC) motor with air-core stator and permanent magnet mover. And to investigate the static and dynamic characteristics of air-core TLBLDC motor, the prototype machine is manufactured and analyzed by F.E.M. and Matlab simulink simulations. Especially, dynamic characteristics of air-core TLBLDC motor driven with 6 step inverter are simulated by F.E.M.coupling with external circuit and Matlab simulink program, and measured for the prototype motor. The simulation results are compared to the experimental results such as current waves, thrust and speed curve.
Robust Sensorless Control for Induction Motor Drives Fed by a Matrix Converter with Model Reference Adaptive Control
Sim, Gyung-Hun ; Huh, Sung-Hoi ; Lee, Kyo-Beum ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 610~616
This paper presents a new robust sensorless control system for high performance induction motor drives fed by a matrix converter with variable structure. The lumped disturbances such as parameter variation and load disturbance of the system are estimated by a variable structure approach based on model reference adaptive scheme. A Reduced Order Extended Luenberger Observer(ROELO) is also employed to bring better responses at the low speed operation. Experimental results are shown to illustrate the performance of the proposed system.
Wind Turbine Simulators Considering Turbine Dynamic Characteristics
Park, Hong-Geuk ; Abo-Khalil, Ahmed. G. ; Lee, Dong-Choon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 617~624
This paper proposes design and implementation of wind turbine simulators which incorporate the turbine dynamic characteristics. At first, the turbine output characteristic in steady state is modelled as a function of wind speed and then dynamic characteristics are modelled such as pitch angle control, torsional vibration, tower shadow effect, wind shear effect, and inertia effect. In addition, a wind speed simulator is developed which can generate the real wind speed pattern. The wind turbine simulator is implemented with 3[kW] M-G set(cage-type induction motor coupled with doubly-fed induction generator) at laboratory.
Preparation of Quasi-nano-sized of Ba-Zn Ferrites Powders by Self-Propagating High Temperature Synthesis and Mechanical Milling
Choi, Kyung-Suk ; Lee, Jong-Jae ; Kim, Hyuk-Don ; Choi, Yong ; Lee, Sang-Heon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 625~628
Ba-Zn ferrite powders for electromagnetic insulator were synthesized by self-propagating high-temperature synthesis(SHS) with a reaction of
. In this study, phase indentification of SHS products was carried out by using x-ray diffractometry and quasi-nano sized Ba-Zn powders were prepared by a pulverizing process. SHS mechanism was studied by thermodynamical analysis about oxidation reaction among
, and Fe. As oxygen pressure increases from 0.25 MPa to 1.0 MPa, the SHS reactions occur well and make clearly the SHS products. X-ray analysis shows that final SHS products formed with the ratio of
of 0.25, 1.0 and 4.0, are mainly
. Based on thermodynamical evaluation, the heat of formation increases in the order of
. This supports that
phase is predominately formed during SHS reaction. The SHS reactions to form
depends on oxygen partial pressure, and the heat of formation during the SHS reaction. The SHS reactions tends to occur well with increasing the oxygen partial pressure and BaO2/ZnO ratio in the reactants This means that the SHS reaction for the formation of Ba-Zn ferrite includes the reduction of BaO2/ZnO and the oxidation of Fe.
powders after pulverizing is agglomeratedwith a size of about
, in which quasi-nano sized particles with about 300nm are present.
Estimation Technique for Additional Delay Time due to Interconnection Branches in Source-Termination Scheme
Noh, Kyung-Woo ; Kim, Sung-Bin ; Baek, Jong-Rumn ; Kim, Seok-Yoon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 629~634
In this paper, we propose a simple numerical formula which can estimate the additional delay time due to interconnection branches in general source-termination scheme. We show that interconnection branches have influence on both signal quality and time delay. Using the proposed numerical formula, time delay can be easily predicted by system designers.
Breakdown Voltage and PD Characteristics of
Mixtures in Nonuniform Field
Hwang, Cheong-Ho ; Sung, Heo-Gyung ; Huh, Chang-Su ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 635~640
New gas mixtures are now finding applications such as interrupting media for high-voltage circuit breakers. These mixtures consist of a high content of carbon tetrafluoride(
) added to sulfur hexafluoride(
has been established for the use in gas insulated substations due to its high insulation withstand level and good arc quenching capability. At this paper Breakdown characteristics were investigated for
mixtures when AC voltage and standard lightning impulse voltage(LI) was applied in a needle-plane electrodes. And partial discharge(PD) experiments were carried out in the test chamber which was made in needle-plane electrode. And
-Q-N distribution of partial discharge signals was analyzed. The total pressure of the
mixtures was varied within the range of 0.1-0.5 Mpa in the test chamber. The breakdown voltage in needle-plane electrode displayed N shape characteristics for increasing the content of
at positive impulse voltage and the PD inception voltage was increased slightly when pressure of
Mixtures was increased. Maximum PD inception voltage is showed in 80% SF6/20%
Nurmerical Study on the Discharge Characteristics of Cylindrical Microcavity Structure
Seo, Jeong-Hyun ; Kang, Kyoung-Doo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 641~647
In this paper, we have studied the basic discharge characteristics of ac-type cylindrical microcavity structure. The structure has a two electrodes, which are positioned in the bottom of the cavity and in the side wall of the cylinder, respectively. The discharge showed asymmetric phenomena depending on the position of a cathode electrode. When the bottom electrode was a cathode, the discharge was stronger even though the area of the cathode was smaller than that of the anode. Simulation results revealed that the focused electric field toward the bottom electrode increased ion density in the space which in turn strengthened the cathode sheath and ionization process.
Effect of the Biased Third Electrode of a Wire-Plate Type Plasma Reactor on Corona Discharge and Ozone Generation Characteristics
Jung, Jae-Seung ; Moon, Jae-Duk ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 648~652
Corona discharge and ozone generation characteristics of a wire-plate plasma reactor, with a biased third electrode, have been investigated with an emphasis on the role of the bias voltage and frequency applied on the third electrode. It was found that the wire-plate plasma reactor, with the biased third electrode, had a switching characteristic on its I-V characteristics for negative and positive discharges, which is very different from that of a conventional wire-plate plasma reactor without the third electrode. As a result, the corona discharge and ozone generation characteristics of the proposed plasma reactor could be controlled by adjusting the bias voltage and frequency of the third electrode. The corona onset and breakdown voltages, and ozone generation and yield, were increased compared with those of without the third electrode. These, however, reveal the effectiveness of the biased third electrode.
A New Wire Bonding Technique for High Power Package Transistor
Lim, Jong-Sik ; Oh, Seong-Min ; Park, Chun-Seon ; Lee, Yong-Ho ; Ahn, Dal ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 653~659
This paper describes the design of high power transistor packages using high power chip transistor dies, chip capacitors and a new wire bonding technique. Input impedance variation and output power performances according to wire inductance and resistance for internal matching are also discussed. A multi crossing type(MCT) wire bonding technique is proposed to replace the conventional stepping stone type(SST) wire bonding technique, and eventually to improve the output power performances of high power transistor packages. Using the proposed MCT wire bonding technique, it is possible to design high power transistor packages with highly improved output power compared to SST even the package size is kept to be the same.
Improvement of Luminous Efficacy in AC PDP with Asymmetric Metal Electrode Structure
Dong, Eun-Joo ; Ok, Jung-Woo ; Yoon, Cho-Rom ; Lee, Hae-June ; Lee, Ho-Joon ; Park, Chung-Hoo ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 660~667
To improve the luminous efficacy of PDPs, an AC PDP with new metal electrode structure is suggested. Operating voltage margin, power consumption, luminance, luminous efficacy, addressing jitter and ICCD image of test panel with proposed structure are measured, to compared with performances of the conventional ITO structure and proposed structures. To enhance luminous efficacy, we designed new structure which have asymmetric metal electrode structure. The experimental results show that the suggested structure shows luminance to maximum 89% and luminous efficacy to maximum 107% compared with conventional ITO standard structure. In addition, proposed structures with asymmetric electrode show low power consumption by
, high luminance by
, and high luminous efficacy by
compared with proposed symmetric electrode structures.
] Tracking Control of Time-delayed Linear Systems with Saturating Actuators
Yi, Yearn-Gui ; Kim, Jin-Hoon ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 668~676
In this paper, we considered the
tracking control for time-delayed linear systems with saturating actuators. The considered time delay is a time varying one having bounded magnitude and rate, and the considered tracking reference is a general one only known its bounds of magnitude and rate. First, we have converted the
tracking control problem into an equivalent
disturbance attenuation problem using two steps of transformations. Next, based on a new Lyapunov-Krasovskii functional, we have derived the result in the form of LMI with two non-convex parameters. Finally, by numerical examples, we have shown the usefulness and effectiveness of our result.
Obstacle Detection and Classification Algorithm using a Laser Scanner
Lee, Gi-Roung ; Hong, Suk-Kyo ; Chwa, Dong-Kyoung ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 677~685
This paper proposes algorithm for the obstacle detection and classification using a single laser scanner. In a measurement data from a laser scanner, there exist points with large differential value called singular points, which can be used to obtain the boundary of an obstacle such that obstacle information can be analyzed. On the other hand, measurement data include a lot of measurement error, which makes it difficult to analyze the accurate obstacle information. To solve this problem, the least square estimation algorithm is used to obtain the accurate information using a single laser scanner, by compensation for the measurement error. This algorithm can be used for the effective obstacle avoidance of mobile robots, and the experimental results are included to demonstrate the effectiveness of the propose algorithm.
A Data Fusion Method of Odometry Information and Distance Sensor for Effective Obstacle Avoidance of a Autonomous Mobile Robot
Seo, Dong-Jin ; Ko, Nak-Yong ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 686~691
This paper proposes the concept of "virtual sensor data" and its application for real time obstacle avoidance. The virtual sensor data is virtual distance which takes care of the movement of the obstacle as well as that of the robot. In practical application, the virtual sensor data is calculated from the odometry data and the range sensor data. The virtual sensor data can be used in all the methods which use distance data for collision avoidance. Since the virtual sensor data considers the movement of the robot and the obstacle, the methods utilizing the virtual sensor data results in more smooth and safer collision-free motion.
The Operational Optimization of Semiconductor Research and Development Fabs by FAB-wide Scheduling
Kim, Young-Ho ; Lee, Jee-Hyong ; Sun, Dong-Seok ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 692~699
Semiconductor research and development(R&D) fabs are very different than production fabs in many ways such as the scales of production, job priority, production methods, and performance measures. Efficient operations of R&D fabs are very important to the development of new product, process stability, high yield, and ultimately company competitiveness. This paper proposes the fab-wide scheduling method for operational optimization of the R&D fabs. Most scheduling systems of semiconductor fabs have only focused on maximizing throughput of each separated areas without considering WIP(works in process) flows of entire fab. In this paper, we proposes the a fab-wide scheduling system which schedules all lots to entire fab equipment at once. We develop the MIP(mixed integer programing) model which allocates the lots to production equipment considering many constraints of all processes and the CP(constraint programming) model which determines the sequences of the lots in the production equipment. The proposed FAB-wide scheduling model is applied to the newly constructed R&D fab. As a result, we have accomplished the system based automated job reservation, decrease of the hot lot delay, increase of the queue time satisfaction, the high throughput by maximizing the batch sizes, decrease of the WIP TAT(Turn Around Time).
Object Classification Method using Hilbert Scanning Distance
Choi, Jeong-Hwan ; Baek, Young-Min ; Choi, Jin-Young ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 700~705
In this paper, we propose object classification algorithm for real-time surveillance system. We have approached this problem using silhouette-based template matching. The silhouette of the object is extracted, and then it is compared with representative template models. Template models are previously stored in the database. Our algorithm is similar to previous pixel-based template matching scheme like Hausdorff Distance, but we use 1D image array rather than 2D regions inspired by Hilbert Path. Transformation of images could reduce computational burden to compute similarity between the detected image and the template images. Experimental results show robustness and real-time performance in object classification, even in low resolution images.
A JTAG Protection Method for Mobile Application Processors
Lim, Min-Soo ; Park, Bong-Il ; Won, Dong-Ho ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 706~714
In this paper, we suggest a practical and flexible system architecture for JTAG(Joint Test Action Group) protection of application processors. From the view point of security, the debugging function through JTAG port can be abused by malicious users, so the internal structures and important information of application processors, and the sensitive information of devices connected to an application processor can be leak. This paper suggests a system architecture that disables computing power of computers used to attack processors to reveal important information. For this, a user authentication method is used to improve security strength by checking the integrity of boot code that is stored at boot memory, on booting time. Moreover for user authorization, we share hard wired secret key cryptography modules designed for functional operation instead of hardwired public key cryptography modules designed for only JTAG protection; this methodology allows developers to design application processors in a cost and power effective way. Our experiment shows that the security strength can be improved up to
second when using 160-bit secure hash algorithm.
Gradient-based Fast Connectivity Weighted Hough Transform
Kim, Jeong-Tae ; Shin, Ji-Young ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 715~717
The connectivity weighted Hough transform is a useful method for detecting well-connected short lines without generating false lines yet requires extensive computation. This letter describes a method that reduces the computation of the connectivity weighted Hough transform by removing unnecessary weight calculations using the gradient angles of feature points. In simulations with synthetic images and experiments with liquid crystal display panel images, the proposed method showed significantly improved speed without compromising detectability.
Robust Decoding of Barcode Signals Acquired under Nonuniform Illumination
Lee, Han-A ; Kim, Jeong-Tae ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 718~724
We present a novel joint barcode deblurring and nonuniform illumination compensation algorithm for barcode signals whose number of modules is known. The proposed algorithm is based on a penalized least squares method using a roughness penalty function for an illumination model and a double well penalty function for a barcode signal model. In simulations, the proposed method shows an improved performance compared with a conventional method without compensating nonuniform illumination effects. In addition, the proposed method converges quickly during optimization(within 15 iterations), thereby showing strong possibility for real time decoding of barcode signals.
Characteristics of the Muscular Activities on the Feedback Control of Elbow Orthosis Using Pneumatic Rubber Artificial Muscle
Hong, Kyung-Ju ; Kim, Kyung ; Kwon, Tae-Kyu ; Kim, Dong-Wook ; Kim, Nam-Gyun ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 725~728
An elbow orthosis with a pneumatic rubber actuator has been developed to assist and enhance upper limbs movements and has been examined for the effectiveness. The effectiveness of the elbow orthosis was examined by comparing muscular activities during alternate dumbbell curl motion wearing and not wearing the orthosis. The subjects participated in the experiment were younger adults in their twenties. The subjects were instructed to perform dumbbell curl motion in a sitting position wearing and not wearing orthosis in turn and a dynamometer was used to measure elbow joint torque outputs in an isokinetic mode. Orthosis was controlled using contractile muscle force that is measured from force sensor through cDAQ-9172 board. The air pressure of the pneumatic actuator was 0.3MPa the most suitable air pressure. For the analysis of muscular activities, Electromyography of the subjects was measured during alternate dumbbell curl motion. The experiment results showed that the muscular activities wearing the elbow orthosis were reduced. With this, we confirmed the effectiveness of the developed elbow orthosis.
Time-frequency Analysis of Vibroarthrographic Signals for Non-invasive Diagnosis of Articular Pathology
Kim, Keo-Sik ; Song, Chul-Gyu ; Seo, Jeong-Hwan ;
The Transactions of The Korean Institute of Electrical Engineers, volume 57, issue 4, 2008, Pages 729~734
Vibroarthrographic(VAG) signals, emitted by human knee joints, are non-stationary and multi-component in nature and time-frequency distributions(TFD) provide powerful means to analyze such signals. The objective of this paper is to classify VAG signals, generated during joint movement, into two groups(normal and patient group) using the characteristic parameters extracted by time-frequency transform, and to evaluate the classification accuracy. Noise within TFD was reduced by singular value decomposition and back-propagation neural network(BPNN) was used for classifying VAG signals. The characteristic parameters consist of the energy parameter, energy spread parameter, frequency parameter, frequency spread parameter by Wigner-Ville distribution and the amplitude of frequency distribution, the mean and the median frequency by fast Fourier transform. Totally 1408 segments(normal 1031, patient 377) were used for training and evaluating BPNN. As a result, the average value of the classification accuracy was 92.3(standard deviation
)%. The proposed method was independent of clinical information, and showed good potential for non-invasive diagnosis and monitoring of joint disorders such as osteoarthritis and chondromalacia patella.