Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of information and communication convergence engineering
Journal Basic Information
Journal DOI :
The Korean Institute of Information and Commucation Engineering
Editor in Chief :
Volume & Issues
Volume 2, Issue 4 - Dec 2004
Volume 2, Issue 2 - Jun 2004
Volume 2, Issue 3 - Mar 2004
Volume 2, Issue 1 - Mar 2004
Selecting the target year
An efficient Channel Estimation Technique of OFDM-Base Space-Time Coded Wireless LAN Systems
Kim, Dong-Ok ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 61~66
This paper presents a way to maximize transmission efficiency and reception ability through transmission diversity technology, which can be adapted to wireless multimedia Wireless LAN system. The presented method is a comparative analysis between a case where parameter a for time average is 0.3.1 with consideration of channel presumption with two types of rms delayed spread, which is 50nsec. 150nsec, for the performance analysis of STTC (Space-Time Trellis Code) adopting time-space ciphering method appropriate for MIMO channel, and performance in the case where presumed channel value from long training column section is applied to according frame in a single frame. The result showed that BER brought SNR improvement of l.0dB in
when a was 0.3 than adopting only the long training column, and showed increase of general performance improvement for the sake of time average rather than the case without.
Novel High-Rate High-Performance Space-Time Codes
Le, Minh-Tuan ; Linh Mai ; Pham, Van-Su ; Yoon, Gi-Wan ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 67~70
In this paper, we propose two novel high-rate high-performance space-time codes for multiple-input multiple-output (MIMO) systems. When
transmit antennas and When
receive antennas are deployed, the two proposed codes respectively offer transmission rates of (When
-1) and (When
-2) symbols per channel use and diversity orders of 3 and 5. As a consequence, our proposed codes allow the MIMO systems to employ a simple detection technique based on QR decomposition. Moreover, for equal or even higher spectral efficiencies, our proposed codes always provide much better bit error rate (BER) performances than V-BLAST architecture does when When
. Computer simulation is given to verify performances of our proposed codes.
Pre-select Diversity with the Aid of Downlink Beamforming in Indoor MC-CDMA System
Pham, Van-Su ; Le, Minh-Tuan ; Linh Mai ; Yim, Mun-Hyuk ; Yoon, Gi-Wan ; Kim, Dong-Hyun ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 71~75
In non-selective frequency environment, it is difficult to take the advantage of path diversity. In the literature, some methods have been proposed to solve the issue. This paper presents a new method to obtain the resolvable path in Indoor Multi-carrier Code Division Multiple Access (MC-CDMA) system by using downlink beam forming. With the aid of downlink beamforming, the most reliable path is found and chosen for the communication link. The new approach is evaluated in term of bit error rate (BER) and power consumption. The simulation results show that the new approach can get better BER performance. However, the cost of BER improvement is a small degradation in power reservation.
Direct Sequence Spread Spectrum Transmitter using FPGAs
Abhijit S. Pandya ; Souza, Ralph-D′ ; Chae, Gyoo-Yong ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 76~79
The DS-SS (Direct Sequence Spread Spec1nun) transmitter is part of a low data rate (∼150 kbps - burst rate and 64 bps - average data rate) wireless communication system. It is traditionally implemented using Digital Signal processing chip (DSP). However, with rapid increase in variety of services through cell phones, such as, web access, video transfer, online games etc. demand for higher rate is increasing steadily. Since the chip rate and thereby the sampling rate requirements of the system are fairly high, the transmitter should implemented using Field programmable Gate Arrays FPGAs instead of a DSP. This paper shows the steps taken to get a working prototype of the transmitter unit on a FPGA based platform.
LMS for Web based e-Learning on the SCORM
Woo, Young-Hwan ; Chung, Jin-Wook ; Kim, Seok-Soo ; Kim, Soon-Gohn ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 80~83
The core purpose of the system proposed in this paper is to help learners pursue proactive and self-oriented education by allowing learners to proactively configure their own content, that is, learners no longer have to be restricted by prescribed sequence of lectures. Although a variety of standardization and Learning Management System (LMS) were produced to develop and effectively manage web contents in response to active diffusion of internet application, practical changes to assist online learners are not yet to be found. In this paper, I would like to introduce a LMS that can support self-leading education by providing various types of learners at Virtual University with delicately organized educational contents for maximum efficiency. The system allows a learner to select a lecture or a chapter which has been presorted to meet his educational needs and intellectual ability. In general, most LMSs cannot meet every individual's educational needs because they structure their programs by letting learners simply choose from a list of available lectures at prescribed level or difficulty. However the Self-Leading LMS eliminates such boundaries by allowing learners to choose contents and difficulty within the limit set by their own educational competence.
Agent Intrusion Detection Model In Attributed Environment
Jeong, Jong-Geun ; Kim, Chul-Won ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 84~88
Firewall is not perfectly prevent hacker, Intrusion Detection System(IDS) is considered a next generation security solution for more trusted network i and system security. We propose a agent IDS model in the different platforms that can detect intrusions in the expanded distributed host environment, since that is a drawback of existing IDS. Then we implement a prototype and verify validity. We use a pattern extraction agent so that we extract audit files needed in intrusion detection automatically even in other platforms.
An Analysis on the Echo Cancellation Algorithm Reducing the Computational Quantities
Lee, Haeng-Woo ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 89~92
An adaptive algorithm for reducing the hardware complexity is presented. This paper proposes a modified LMS algorithm for the adaptive system and analyzes its convergence characteristics mathematically. An objective of the proposed algorithm is to reduce the hardware complexity. In order to test the performances, it is applied to the echo canceller, and a program is described. The results from simulations show that the echo canceller adopting the proposed algorithm achieves almost the same performances as one adopting the NLMS algorithm. If an echo canceller is implemented with this algorithm, its computation quantities are reduced to the one third as many as the one that is implemented with the NLMS algorithm, without so much degradation of performances.
Fabrication of Thin Film Transistor Using Ferroelectrics
Hur, Chang-Wu ; Kim, Jung-Tae ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 93~96
The a-Si:H TFT using ferroelectric of
as a gate insulator is fabricated on glass. Dielectric characteristics of ferroelectric are superior to
. Ferroelectric increases on-current, decreases threshold voltage of TFT and also improves breakdown characteristics. The a-SiN:H has optical band gap of 2.61 eV, retractive index of 1.8∼2.0 and resistivity of
cm, respectively. Insulating characteristics of ferroelectrics are excellent because dielectric constant of ferroelectric is about 60∼100 and breakdown strength is over 1MV/cm. TFT using ferroelectric has channel length of 8∼20
and channel width of 80∼200
. And it shows that drain current is 3.4
at 20 gate voltage,
is a ratio of
is 4∼5 volts, respectively. In the case of TFT without ferroelectric, it indicates that the drain current is 1.5
at 20 gate voltage and
is 5∼6 volts. With the improvement of the ferroelectric thin film properties, the performance of TFT using this ferroelectric has advanced as a gate insulator fabrication technology is realized.
Self-Directed Learning Evaluation Using Fuzzy Grade Sheets
Kim, Kwang-Baek ; Kim, Byung-Joo ; Cho, Jae-Hyun ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 97~101
This paper is about the use of existing evaluation methods, which evaluate learning determined by the score of an exam, which is either a multiple-choice type or single choice type question. These scores don't show the objective evaluations that cause some negative opinions about the scores. In this paper, we propose that the evaluation of the methods of self-directed learning use the triangle-type function of the fuzzy theory so that the learner can objectively evaluate their own learning ability. The proposed method classifies the result of learning into three fuzzy grades to calculate membership, and evaluate the result of an exam according to the final fuzzy grade degree as applied to the fuzzy grade sheets.
5-GHz Delay-Locked Loop Using Relative Comparison Quadrature Phase Detector
Wang, Sung-Ho ; Kim, Jung-Tae ; Hur, Chang-Wu ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 102~105
A Quadrature phase detector for high-speed delay-locked loop is introduced. The proposed Quadrature phase detector is composed of two nor gates and it determines if the phase difference of two input clocks is 90 degrees or not. The delay locked loop circuit including the Quadrature phase detector is fabricated in a 0.18 um Standard CMOS process and it operates at 5 GHz frequency. The phase error of the delay-locked loop is maximum 2 degrees and the circuits are robust with voltage, temperature variations.
Web Server Cluster Load Balancing
Kyung Sung ; Kim, Seok-Soo ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 106~109
This study designs a load balancer via direct routing that share a virtual service on a single IP address in the Linux system and suggests an efficient load balancing method to improve transmission speed in the web server cluster environment. It will increase performance and scalability with fast packet transfer and removing bottleneck problem by using TCP Splicing and Content-Aware Distributor method. This method is expected to be the noticeable technology that provides an important interface, which make application services for e-commerce effectively be applied to high-speed network infrastructure. At this time, it is required to study further on the optimum balancing method in the web server cluster environment so as to apply the hybrid (optimum load balancing method by software and hardware) method and improve the reuse of security cession based on high-speed TCP connections.
Modeling and Posture Control of Lower Limb Prosthesis Using Neural Networks
Lee, Ju-Won ; Lee, Gun-Ki ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 110~115
The prosthesis of current commercialized apparatus has considerable problems, requiring improvement. Especially, LLP(Lower Limb Prosthesis)-related problems have improved, but it cannot provide normal walking because, mainly, the gait control of the LLP does not fit with patient's gait manner. To solve this problem, HCI((Human Computer Interaction) that adapts and controls LLP postures according to patient's gait manner more effectively is studied in this research. The proposed control technique has 2 steps： 1) the multilayer neural network forecasts angles of gait of LLP by using the angle of normal side of lower limbs； and 2) the adaptive neural controller manages the postures of the LLP based on the predicted joint angles. According to the experiment data, the prediction error of hip angles was 0.32［deg.］, and the predicted error of knee angles was 0.12［deg.] for the estimated posture angles for the LLP. The performance data was obtained by applying the reference inputs of the LLP controller while walking. Accordingly, the control performance of the hip prosthesis improved by 80% due to the control postures of the LLP using the reference input when comparing with LQR controller.
Forecasting of new businesses after restructuring of power industry
Koo, Young-Duk ; Kim, Eun-Sun ; Park, Young-Seo ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 116~118
In the power industry after restructuring of Power industry will be appeared on-site type business, power retail sales business, and power wholesales business, power dealing business, customer inclination business ＆ delivery of power facilities. Among them, power trade business, customer inclination business and on-site type business will be rapidly increased and occupied attention. In addition, it is forecasted to advent the broker, provider, market place, power marketer, system operator and generator as a main player. Meanwhile, it needs protection of existing power industry and activation of new energy market for accomplishment of restructuring of power industry.
Study on Establishment of National Technology Transfer System
Kim, Eun-Sun ; Koo, Young-Duk ; Park, Young-Seo ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 119~122
In this paper, we examine the necessity and the role of technology transfer/diffusion in the frame of national technology innovation system. On the base of this, we present a construction plan of technology transfer/diffusion system to make the national electric industry for 21st century to possess the competitive power. To achieve above purpose, we examine the relations between theory of technology transfer/diffusion structure and policy. Furthermore, we try to find the necessity for construction of technology transfer ＆ diffusion system and a driving plan. Then, it is analyzed that expected design requirements for the construction of electric technology transfer ＆ diffusion system. Finally, construction and activation plan for electric technology transfer ＆ diffusion system are presented, which would strengthen the national technology competitiveness.
A New Method for Color Feature Representation of Color Image in Content-Based Image Retrieval - 2D Projection Maps
Ha, Seok-Wun ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 123~127
The most popular technique for image retrieval in a heterogeneous collection of color images is the comparison of images based on their color histogram. The color histogram describes the distribution of colors in the color space of a color image. In the most image retrieval systems, the color histogram is used to compute similarities between the query image and all the images in a database. But, small changes in the resolution, scaling, and illumination may cause important modifications of the color histogram, and so two color images may be considered to be very different from each other even though they have completely related semantics. A new method of color feature representation based on the 3-dimensional RGB color map is proposed to improve the defects of the color histogram. The proposed method is based on the three 2-dimensional projection map evaluated by projecting the RGB color space on the RG, GB, and BR surfaces. The experimental results reveal that the proposed is less sensitive to small changes in the scene and that achieve higher retrieval performances than the traditional color histogram.
A Study on User Authorization for Grid Resources
Lee, Seoung-Hyeon ; Lee, Won-Goo ; Lee, Jae-Kwang ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 128~131
We suggest resource authorization system based on RBAC admitting someone to access resources. In existing grid environment, The authorization mechanism on user's resource is to give users an authority on the basis of DN(Distinguished Name) of proxy certificate and map file mapped in local system ID by one-to-one. In this case, it is difficulty in resource management such as each accounting management, memory resource, and disk resource, if the number of users, who want to use them is increased. To solve this problem, we specify the role of user's task in extension fields of his proxy certificate instead of the authorization mechanism of user's ID and propose resource authorization system being able to access his resource.
Information Processing in Primate Retinal Ganglion
Je, Sung-Kwan ; Cho, Jae-Hyun ; Kim, Gwang-Baek ;
Journal of information and communication convergence engineering, volume 2, issue 2, 2004, Pages 132~137
Most of the current computer vision theories are based on hypotheses that are difficult to apply to the real world, and they simply imitate a coarse form of the human visual system. As a result, they have not been showing satisfying results. In the human visual system, there is a mechanism that processes information due to memory degradation with time and limited storage space. Starting from research on the human visual system, this study analyzes a mechanism that processes input information when information is transferred from the retina to ganglion cells. In this study, a model for the characteristics of ganglion cells in the retina is proposed after considering the structure of the retina and the efficiency of storage space. The MNIST database of handwritten letters is used as data for this research, and ART2 and SOM as recognizers. The results of this study show that the proposed recognition model is not much different from the general recognition model in terms of recognition rate, but the efficiency of storage space can be improved by constructing a mechanism that processes input information.