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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of IKEEE
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Institude of Korean Electrical and Electronics Engineers
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Volume & Issues
Volume 5, Issue 2 - Dec 2001
Volume 5, Issue 1 - Jul 2001
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Photovoltaic Generation System Simulation using Real Field Weather Conditions
Park, Min-Won ; Yu, In-Keun ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 121~127
Actual system apparatuses are necessary in order to verify the efficiency and stability of photovoltaic(PV) generation systems considering the size of solar panel, the sort of converter type, and the load conditions and so on. Moreover, it is hardly possible to compare a certain MPPT control scheme with others under the exactly same weather and load conditions as well. For the purpose of solving above mentioned difficulties in a laboratory basis, a transient simulation of PV generation system using real field weather conditions is indispensable. A straightforward simulation scheme with cost effective hardware structures under real weather conditions is proposed in this paper using EMTDC type of transient analysis simulators. Firstly, a solar cell has been modeled with VI characteristic equations, and then the real field data of weather conditions are interfaced to the EMTDC through Fortran program interface method. As a result, the stability and the efficiency analysis of PV generation systems according to various hardware structures and MPPT controls are easily possible under the exactly same weather conditions.
Rigorous Design of Optical Directional Filters using MTLT
Park, Jai-Seo ; Hong, Kwon-Eui ; Ho, Kwang-Chun ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 128~135
Optical wavelength filters based on directional couplers are rigorously designed and analyzed by Modal Transmission-Line Theory (MTLT). The conventional parallel directional coupler is utilized to implement a narrow-band filter, and it takes up the coupler with tapered structure as a wide-band filter. The power transfers of TE/TM modes in narrow-band filters are maximized at
, and the optical bandwidths are then 30nm and 10nm, respectively. Furthermore, when the coupling lengths of TE/TM modes in wide-band filters operating at
are selected as
, those are operated as the stop-band and pass-band filters, respectively.
A Study on Scheme to Support QoS using Differentiated Services in MPLS Network
Park, Chun-Kwan ; Jeon, Byung-Chun ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 136~145
As with appearing new applications that requires QoS guarantee such as VoIP, VPN in Internet, problems of IP QoS has been one of most important issues in next-generation Internet. IETF has proposed integrated services model(Int-Serv) and differentiated service(Diff-Serv) to supply IP QoS in Internet. Int-Serv model uses the state information of each IP flow, so satisfies QoS according to traffic characteristics, but increases the amount of flow state information with increasing flow number. Diff-Serv model uses PHP(Per Hop Behavior), and there are well-defined classes to provide differentiated traffics with different services according to delay and loss sensitivity. Diff-Serv model can provide diverse services in Internet because of having no the state and signal information of each flow. As MPLS uses the packet forwarding technique based-on label, it implements the traffic engineering in the networks easily. The MPLS can set up the path with different traffic parameters, and assign each path to particular Class of Services. Therefore it is possible to support the Diff-Serv model with well-defined classes. In this paper we investigate the performance improvement of Diff-Serv function in the MPLS network to guarantee class of services in Internet.
Control of DSTATCOM for Line Voltage Regulation
Jung, Soo-Young ; Kim, Tae-Hyun ; Moon, Seung-Il ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 146~152
Two control techniques - PI and LQR(Linear Quadratic Regulator) - of DSTATCOM (Distribution Static Synchronous Compensator) for line voltage regulation in distribution system are presented. It is shown that the voltage waveform is improved if the proposed methods are applied in IEEE 13 radial distribution system using PSCAD/EMTDC package in case of single line-to-ground fault. The three cases - without control, with PI control and with LQR control - are compared. The LQR control is shown to be best in respect of response profile and control effort required among them.
Dynamic Electrical Impedance Tomography with Internal Electrodes
Kang, Suk-In ; Kim, Kyung-Youn ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 153~163
Electrical impedance tomography(EIT) is a relatively new imaging modality in which the internal impedivity distribution is reconstructed based on the known sets of injected currents and measured voltages on the surface of the object. We describe a dynamic EIT imaging technique for the case where the resistivity distribution inside the object changes rapidly within the time taken to acquire a full set of independent measurement data. In doing so, the inverse problem is treated as the state estimation problem and the unknown state (resistivity) is estimated with the aid of extended Kalman filter in a minimum mean square error sense. In particular, additional electrodes are attached to the known internal structure of the object to enhance the reconstruction performance and modified Tikhonov regularization technique is employed to mitigate the ill-posedness of the inverse problem. Computer simulations are provided to illustrate the reconstruction performance of the proposed algorithm.
Design and Implementation of Hard Embedded Real-Time System
Lin, Chi-Ho ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 164~173
In this paper, we have designed and implemented a new hard embedded real-time system to satisfy hard real-time constraints in moving independently. Real-time kernel should be small size, fast and predictable. Because of the great variety of demands on real time scheduling, a real time kernel should also include a flexible and re-programmable task scheduling discipline. In this paper, we present that real-time applications should be split into small and simple parts with hard real-time constraints. To satisfy these properties, we designed real-time kernel and general kernel, that have their different properties. In real-time tasks, interrupt processing should be run. In general kernel, non real time tasks or general tasks are run. The efficiency of the proposed hard embedded real-time system is shown by comparison results for performance of the proposal real time kernel with both RT-Linux and QNX.
A Study on the Implementation of the Web-Camera System for Realtime Monitoring
Ahn, Young-Min ; Jin, Hyun-Joon ; Park, Nho-Kyung ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 174~181
In this study, the architecture of the Web Camera System for realtime monitoring on Internet is proposed and implemented in two different structures. In the one architecture, a Web-server and a Camera-server are implemented on the same system, and the system transfers motion pictures compressed to JPEG file to users on the WWW(World Wide Web). In the other architecture, the Web-server and the Camera-server are implemented on different systems, and the motion pictures are transferred from the Camera-server to the Web-server, and finally to users. For JPEG image transferring in the Web Camera system, the Java Applet and the Java Script are used to maximize flexibility of the system from the Operating system and the Web browsers. In order to compare system performance between two architectures, data traffic is measured and simulated in the unit of byte per second.
Behavior of an Automatic Pacemaker Sensing Algorithm for Single-Pass VDD Atrial Electrograms
Kim, Jung-Kuk ; Lee, Seung-Han ; Huh, Woong ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 182~189
Single-pass VDD pacemakers have been used as a result of simple implantation procedures and generally reliable atrial tracking that ensures an A-V sequence pacing. However, there is a controversy over their reliabilities of atrial tracking. As a new sensing method for reliable atrial tracking, a simple automatic pacemaker sensing algorithm was implemented and evaluated to validate its benefits in sensing depolarization waves of Single-pass VDD atrial electrograms. The automatic sensing algorithm had a predetermined sensing dynamic range and the sensitivity level was controlled as 50% of the average of two most recently sensed intrinsic amplitudes. The behavior of the automatic sensing algorithm in the Single-pass VDD atrial electrograms was analyzed and characterized. It was observed that the automatic sensing algorithm was more effective than a conventional fixed threshold method to accurately detect and track p-waves in Single-pass VDD electrograms.
A Study on Defect Recognition of Laser Welding using Histogram and Fuzzy Techniques
Jang, Young-Gun ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 190~200
This paper is addressed to welding defect feature vector selection and implementation method of welding defect classifier using fuzzy techniques. We compare IAV, zero-crossing number as time domain analysis, power spectrum coefficient as frequency domain, histogram as both domain for welding defect feature selection. We choose histogram as feature vector by graph analysis and find out that maximum frequent occurrence number and section of corresponding signal scale in relative histogram show obvious difference between normal welding and voiding with penetration depth defect. We implement a fuzzy welding defect classifier using these feature vector, test it to verify its effectiveness for 695 welding data frame which consist of 4000 sampled data. As result of test, correct classification rate is 92.96%. Lab experimental results show a effectiveness of fuzzy welding defect classifier using relative histogram for practical Laser welding monitoring system in industry.
Wavelength and Repetition-Rate Tunable Optical Pulse Generation for Ultrafast OTDM/WDM
Choi, Kyoung-Sun ; Han, Chong-Min ; Seo, Dong-Sun ; Jhon, Young-Min ; Lee, Seok ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 201~210
Wavelength and repetition-rate tunable optical pulse-trains for ultrafast optical time- and wavelength division multiplexing are generated from a semiconductor fiber ring laser by optical injection mode-locking. The pulse trains show the pulse with of
ps and the wavelength tuning of wider than 30 nm at various repetition-rates of 10 GHz, 20 GHz, 30 GHz and 40 GHz, respectively.
Multitexture Image Segmentation Using Amplitude Demodulation
Lee, Hyun-Soo ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 211~220
This paper proposes a 2-D texture segmentation algorithm which is in close analogy to amplitude demodulation in communication systems. First, we show that it is theoretically possible to segment a multitexture image using an ideal filter followed by an amplitude demodulation block. However, in practice, the Gabor filter is used instead of the ideal filter because it has many desirable properties and especially it gives optimum space-bandwidth product. Our algorithm recovers all the texture regions containing the sinusoid with frequency to which the Gabor filter is tuned. We have demonstrated the discriminating power of our method in using a synthetic multitexture image. It is clear mathematically and easy to implement. Our method can be a good alternative to avoid many problems encountered in classifying the feature vectors in feature-based texture segmentation approaches.
An Efficient Requantization Method for INTRA Frames in Heterogeneous Transcoding
Seo, Kwang-Deok ; Kim, Jae-Kyoon ;
Journal of IKEEE, volume 5, issue 2, 2001, Pages 221~231
In this paper, we propose an efficient requantization method for INTRA frames in heterogeneous transcoding from MPEG-1 to MPEG-4 simple profile. The quantizer for MPEG-1 INTRA MB usually uses a quantization weighting matrix while the quantizer for MPEG-4 simple profile doesn't. As a result, the quantization step sizes of the two quantizers may not be the same even for the same quantization parameter. Due to this mismatch in the quantization step site, the transcoded MPEG-4 sequence suffers from serious quality degradation and the number of bits produced by transcoding increases from the original MPEG-1 video sequence. To solve these problems, we propose an efficient method to find a near-optimum reconstruction level in the transcoder. We also present a PDF (probability distribution function) estimation method for the original DCT coefficients of MPEG-1 video sequence, which is required for the proposed requantization. Experimental results show that the proposed method gives
improvement in PSNR over the conventional method, even at the reduced bit-rate about
from the conventional method.