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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of IKEEE
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Journal DOI :
Institude of Korean Electrical and Electronics Engineers
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Volume & Issues
Volume 2, Issue 2 - Dec 1998
Volume 2, Issue 1 - Aug 1998
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A Study on the Mobile Communication System for the Ultra High Speed Communication Network
Kim, Kab-Ki ; Moon, Myung-Ho ; Shin, Dong-Hun ; Lee, Jong-Arc ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 1~14
In this paper, Antenna, LNA, Mixer, VCO, and Modulation/Demodulation in Baseband processor which are the RF main components in Wireless LAN system for ultra high-speed communications network are studied. Antenna bandwidth and selective fading due to multipath can be major obstacles in high speed digital communications. To solve this problem, wide band MSA which has loop-structure magnetic antenna characteristics is designed. Distributed mixer using dual-gate GaAs MESFET can achieve over 10dB LO/RF isolation without hybrid, and minimize circuit size. As linear mixing signal is produced, distortions can be decreased at baseband signals. Conversion gain is achieved by mixing and amplification simultaneously. Mixer is designed to have wide band characteristics using distributed amplifier. In VCO design, Oscillator design method by large signal analysis is used to produce stable signal. Modulation/Demodulation system in baseband processor, DS/SS technique which is robust against noise and interference is used to eliminate the effect of multipath propagation. DQPSK modulation technique with M-sequences for wideband PN spreading signals is adopted because of BER characteristic and high speed digital signal transmission.
Design of a Distributed Mixer Using Dual-Gate MESFET's
Oh, Yang-Hyun ; An, Jeong-Sig ; Kim, Han-Suk ; Lee, Jong-Arc ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 15~23
In this paper, distributed mixer is studied at microwave frequency. The circuit of distributed mixer composed of gate 1,2, drain transmission lines, matching circuits in input and output terminal, DGFET's. For impedance matching of input and output port at higher frequency, image impedance concept is introduced. In distributed mixer, a DGFET's impedances are absorbed by artificial transmission line, this type of mixer can get a very broadband characteristics compared to that of current systems. A RF/LO signal is applied to each gate input port, and are excited the drain transmission line through transcondutance of the DGFET's. The output signals from each drain port of DGFET's added in same phases. We designed and frabricated the distributed mixer, and a conversion gain, noise figure, bandwidth, LO/RF isolation of the mixer are shown through computer simulation and experimentation.
Neural Learning Algorithms for Independent Component Analysis
Choi, Seung-Jin ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 24~33
Independent Component analysis (ICA) is a new statistical method for extracting statistically independent components from their linear instantaneous mixtures which are generated by an unknown linear generative model. The recognition model is learned in unsupervised manner so that the recovered signals by the recognition model become the possibly scaled estimates of original source signals. This paper addresses the neural learning approach to ICA. As recognition models a linear feedforward network and a linear feedback network are considered. Associated learning algorithms for both networks are derived from maximum likelihood and information-theoretic approaches, using natural Riemannian gradient . Theoretical results are confirmed by extensive computer simulations.
A Mixed-Signal IC for Magnetic Stripe Storage System
Lim, Shin-Il ; Choi, Jong-Chan ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 34~41
An integrated circuit for magnetic stripe storage system is implemented. All the analog and digital circuits are integrated in one chip. The analog block contains preamplifier, peak detecter, comparator and reference generater. And digital block includes reference window signal generater, up/down counter for F/2F signal measurement, bit-error detection logic, and control logic. Both the encoding and decoding functions for F/2F signal processing are provided. An AGC(automatic gain control) circuit which was included in conventional circuits is eliminated due to optimized circuit design. Misreading prevention circuits are also proposed by fixing up new reference bit when broken bits are detected. The prototype chip is implemented using
N-well CMOS technology and operates from 3.3 V to 7.5 V of supply voltage. It occupies a die area of
and dissipates 8 mW with a 5 V supply voltage.
A study on the extended TCP/IP protocol for real-time communication
Yoon, Young-Chan ; Park, Jae-Hyun ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 42~52
This paper proposes an extended TCP/IP protocol, LAN/TCP, that can be used for the distributed soft real-time systems connected through the Ethernet-based local area network. Since LAN/TCP shows soft real-time performance with keeping compatibility and interoperability with the standard TCP/IP, the existing application software can be used without any modification. LAN/TCP also provides the periodic transmission mode(PTM) with which the periodical data collection and updating the control signals can be efficiently implemented with relatively small traffic overhead. This paper includes the computer simulation and experimental results of the proposed protocol.
Development of an Optical Range Finder for Surface Roughness Measurements
Eom, Jung-Hyun ; Park, Hyun-Hee ; Seo, Dong-Sun ; Huh, Woong ; Kim, Joon-Bum ; Kim, Yon-Gon ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 53~60
We develope a high repetition rate, short distance, optical range finder for surface roughness measurements of large structures, such as a highway road, etc. For range measurement based on a triangulation principle, we use a light emitting diode and an one dimensional Position sensitive photodetector for a light source and an angle detector of the reflected light at the object, respectively. The range finder has automatic power control and electrical background noise rejection capabilities which enable it to overcome variations of an object reflectance and to eliminate time-varying, as well as constant, background light noises. Our experimental results show less than
of measurement errors regardless of an object reflectance, for
object ranges which are determined by considering the installation of the range finder and the depth of surface roughness.
A Study on the Algorithm Development for Speech Recognition of Korean and Japanese
Lee, Sung-Hwa ; Kim, Hyung-Lae ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 61~67
In this thesis, experiment have performed with the speaker recognition using multilayer feedforward neural network(MFNN) model using Korean and Japanese digits . The 5 adult males and 5 adult females pronounciate form 0 to 9 digits of Korean, Japanese 7 times. And then, they are extracted characteristics coefficient through Pitch deletion algorithm, LPC analysis, and LPC Cepstral analysis to generate input pattern of MFNN. 5 times among them are used to train a neural network, and 2 times is used to measure the performance of neural network. Both Korean and Japanese, Pitch coefficients is about 4%t more enhanced than LPC or LPC Cepstral coefficients.
A study on the Improvement of TCP over ATM
Lee, Jin-Woo ; Park, Ki-Tae ; Kim, Jin-Tae ; Kim, Nae-Jin ; Park, In-Kap ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 68~75
The Asynchronous Transfer Mode(ATM) networks are being adopted as backbones over various parts of Internet. Also, TCP is one of the most widespread transport protocols, nowadays. It can be used with ATM. But, TCP shows poor end-to-end performance on ATM networks. Effective throughput of TCP over ATM can be quite low when cells are dropped at the congested ATM switch. The low throughput is due to wasted bandwidth as congested link transmits cells from corrupted packets. This paper examines the behavior of TCP over ATM-UBR using EPD switch in a broadband environment. With a threshold close to the buffer size, the buffer can be used more efficiently, but more drops and retransmission occurs. If the threshold is much less than buffer size, efficient is not good, but few drops can happen. Therefore, decision of the threshold is important.
Performance Improvement by Bridging in MAC for Wireless LAN
Hyun, In-Bok ; Lim, Kwang-Jae ; Kim, Baek-Hyun ; Kwak, Kyung-Sup ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 76~84
In this paper, CSMA/CA with bridging is analyzed which is an added function of relaying directly between access points when wireless terminals can not communicate each other, and is also compared to the CSMA/CA without bridging which is IEEE 802.11 MAC standard. Through simulations, it is shown that the two methods have the similar performance in terms of the throughput but the bridging CSMA/CA improves the delay compared to the non-bridging CSMA/CA.
Performance Comparison of Pilot Channel and Pilot Symbol Methods for DS/CDMA System
Jeong, Sang-Wook ; Shin, Seung-Hoon ; Kwak, Kyung-Sup ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 85~95
We consider two methods for the pilot signal transmission in DS/CDMA systems: Pilot channel method which is parallel to the data channel and pilot symbol method which is serial to the data channel. In this paper, we analyze the two methods. The performance of the two methods is shown to be dependent upon the added noise, fading, pilot symbol period and pilot channel power. Through the analysis, it is found that the performance of the pilot symbol method outperforms compared to the pilot channel method.
Image Browse for JPEG Decoder
Chong, Ui-Pil ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 96~100
Due to expected wide spread use of DCT based image/video coding standard, it is advantageous to process data directly in the DCT domain rather than decoding the source back to the spatial domain. The block processing algorithm provides a parallel processing method since multiple input data are processed in the block filter structure. Hence a fast implementation of the algorithm is well suited. In this paper, we propose the JPEG browse by Block Transform Domain Filtering(BTDF) using subband filter banks. Instead of decompressing the entire image to retrieve at full resolution from compressed format, a user can select the level of expansion required
. Also this approach reduces the computer cpu time by reducing the number of multiplication through BTDF in the filter banks.
A Study on the Micro-defects Characteristics and Latch-up Immune Structure by RTA in 1MeV P Ion Implantation
Roh, Byeong-Gyu ; Yoon, Seok-Beom ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 101~107
This paper is studied micro-defect characteristics by phosphorus 1MeV ion implantation and Rs, SRP, SIMS, XTEM for the RTA process was measured and simulated. As the dose is higher, the Rs is lower. When the dose are
, the Rp are
respectively. As the RTA time is longer, the maximum concentration position is deeper from the surface and the concentration is lower. Before the RTA was done, we didn't observe any defect. But after the RTA process was done, we could observe the RTA process changed the micro-defects into the secondary defects. The simulation using the buried layer and connecting layer structure was performed. As results, the connecting layer had more effect than the buried layer to latch-up immune. Trigger current was more
and trigger voltage was 6V at dose
and the energy 500KeV of connecting layer Lower connecting layer dose, latch-up immune characteristics was better.
Equivalent Network Approach of Planar DFB (Distributed-Feedback) guiding Structures
Kim, June-Hwan ; Ho, Kwang-Chun ; Kim, Yung-Kwon ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 108~113
By using an equivalent network based on Floquet's theorem and bisection principle, the optical properties of planar DFB guiding structure are evaluated. The optical parameters, such as Bragg condition and the reflectivity as a function of grating period, are numerically calculated. The numerical results reveal that this method offers a simple and convenient algorithm to analyze the optical characteristics of DFB configurations.
A Study on Collision Avoidance and Priority Control Scheme for Cells in Frames
Park, Chun-Kwan ; Jeon, Byung-Chun ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 114~121
This paper proposed a collision avoidance scheme to improve the network performance and priority control scheme to support real-time ATM applications in CIF(Cells in Frames), which carries ATM cells over existing Ethernet interfaces. The proposed scheme has optimized for the two nodes Ethernet, that is a typical CIF network, and doesn't require any hardware modification of existing Ethernet interface card. The collision avoidance scheme gives fair access opprtunities with minimized contention to the nodes by assigning different inter-frame gap to each element of CIF network. The priority control scheme guarantees preemptive transmission of real-time frames to the medium by exchanging queuing status information between two nodes. Therefore in this paper it is shown that CIF network which has both the collision avoidance scheme of MAC layer and the priority control scheme of CIF layer has a improved network performance and supports real-time ATM applications efficiently.
A Study on Congestion Control for LAN Interworking in ATM Network
Park, Chun-Kwan ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 122~133
The CL network fer CBDS(Connectionless Broadband Data Service) defined by ITU-(International Telecommunication Union-Telecommunication) consists of CL(ConnectionLess) servers which route frames and links which connect between CL user and CL server or between CL servers. In this configuration, two kinds of congestion, CL link congestion and CL server congestion may occur. Therefore this paper has proposed the scheme that can deal with the above congestion state of LAN traffic efficiently in interworking LANs in ATM network. Proposed schemes ale link-by-link scheme and hybrid scheme. Link-by-link scheme uses the ABR feedback loops of AIM layer between CL user and CL server or between CL servers, and the header translation table carrying out the routing function of frame. And hybrid scheme is the scheme that adds end-to-end loop to link-by-link scheme and then uses RM message using CLNAP-PDU(ConnectionLess Network Access Protocol - Protocol Data Units) of CL layer. These schemes can be implemented easily because of using the ABR loop of ATM layer, end-to-end loop of CL layer, and the routing function of CL server. In this paper the characteristic and effects of two schemes in CL server bas been compared and analyzed.
The Adaptive Congestion Control Using Neural Network in ATM network
Lee, Yong-Il ; Kim, Yung-Kwon ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 134~138
Because of the statistical fluctuations and the high 'time-variability' nature of the traffic, managing the resources of the network require highly dynamic techniques with minimal Intervention and reaction times, and adaptive and learning capabilities. The neural networks normalizes the ATM cell arrival rate and queue length and has the adaptive learning algorithm, and experimentally investigated the method to prevent the congestion generated in ATM networks.
Obstacle Avoidance Algorithm of a Mobile Robot using Image Information
Kwon, O-Sang ; Lee, Eung-Hyuk ; Han, Yong-Hwan ; Hong, Seung-Hong ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 139~149
There are some problems in robot navigations with a single kind of sensor. We propose a system that takes advantages of both CCD camera and ultrasonic sensors for the concerning matter. A coordinate extraction algorithm to avoid obstacles during the navigation is also proposed. We implemented a CCD based vision system at the front part of the vehicle and did experiments to verify the suggested algorithm's availability. From experimental results, the error rate was reduced when a CCD camera was used rather than when only ultrasonic sensors were used. Also we can generate path to avoid those obstacles using the measured values.
Comparisons of Recognition Rates for the Off-line Handwritten Hangul using Learning Codes based on Neural Network
Kim, Mi-Young ; Cho, Yong-Beom ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 150~159
This paper described the recognition of the Off-line handwritten Hangul based on neural network using a feature extraction method. Features of Hangul can be extracted by a
window method which is the modified
mask method. These features are coded to binary patterns in order to use neural network's inputs efficiently. Hangul character is recognized by the consonant, the vertical vowel, and the horizontal vowel, separately. In order to verify the recognition rate, three different coding methods were used for neural networks. Three methods were the fixed-code method, the learned-code I method, and the learned-code II method. The result was shown that the learned-code II method was the best among three methods. The result of the learned-code II method was shown 100% recognition rate for the vertical vowel, 100% for the horizontal vowel, and 98.33% for the learned consonants and 93.75% for the new consonants.
2-D Field Analysis of Flat-type Motor
Kim, Pill-Soo ;
Journal of IKEEE, volume 2, issue 1, 1998, Pages 160~165
This paper describes a method for field analysis inside the flat-type brushless DC motor using 2-D field simulator. Rigorous field analysis entail 3-D analysis. However, this analysis is not often appropriate for system designs because of the time and cost involved. For field analysis in this study, the 3-D problem is reduced to a 2-D boundary value problem by introducing a cylindrical cutting plane at the mean radius of the magnets. Independent of sizes and shapes of systems, the exact 2-D field results can be obtained with reasonable predictability.