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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of information and communication convergence engineering
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Journal DOI :
The Korean Institute of Information and Commucation Engineering
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Volume & Issues
Volume 5, Issue 4 - Dec 2007
Volume 5, Issue 3 - Sep 2007
Volume 5, Issue 2 - Jun 2007
Volume 5, Issue 1 - Mar 2007
Selecting the target year
An MAC Protocol based on Code Status Sensing and Acquisition Indication in CDMA Networks
Lim, In-Taek ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 181~184
In this paper, a CSSMA/AI MAC protocol in packet CDMA network is presented. The main features of this protocol are the code status sensing and reservation for reducing the packet collision. The base station broadcasts the code status on a frame-by-frame basis just before the beginning of each preamble transmission, and the mobile station transmits a preamble for reserving a code based on the received code status. After having transmitted the preamble, the mobile station listens to the downlink of the selected code and waits the base station reply. If this reply indicates that the code has been correctly acquired, it continues the packet transmission for the rest of the frame. If there are other packets waiting for transmission, the base station broadcasts the status of the code as reserved, and the mobile station transmits a packet on a reserved code for the successive frames.
Evaluation of an Efficient Channel Estimator for the STTD Schemes
Kim, Seong-Hwan ; Na, Cheol-Hun ; Ryoo, Sang-Jin ; Hwang, In-Tae ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 185~193
This paper evaluates the performance combining space-time transmit diversity (STTD) and an efficient channel estimator (ECE) for wideband code division multiple access (WCDMA) systems in various mobile channels. Using decision variable (DV), we also derive the analytic bit error rate (BER) and mean square error (MSE) for WCDMA applying ECE for STTD schemes. The simulation results show that the ECE performance is superior to the previous works in  as because we use additional pilot diversity which is so called secondary common control physical channel (S-CCPCH). The performance in case of the channel estimator using only one-channel or two-channel is worse than that of an ECE as about the maximum 4 dB at BER 1.0E-3 satisfying voice service over Rician fading channel. Our results show that, even with ICE, an ECE algorithm are effective in improving the output SNR and significantly reduce the error floor. In addition, the simulation results investigated in this paper also reveal that WCDMA combining an ECE and the STTD scheme could provide appreciable performance improvements in Rayleigh fading channel.
Slotted CDMA_ALOHA Protocol with Hybrid ARQ in Wireless Communication Network
Lim, In-Taek ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 194~199
In this paper, a slotted CDMA_ALOHA protocol with hybrid ARQ is proposed for the wireless CDMA communication networks. The proposed protocol combines the characteristics of the slotted ALOHA, CDMA, and the hybrid ARQ, in order to increase the throughput by reducing the number of retransmissions when the channel experiences heavy traffic. The main feature of the proposed protocol is the utilization of the forward error correction capability to correct errors that appear after the CDMA dispreading of the packets. The base station does not need to ask so often for retransmission of erroneous packets. It will request for retransmission only when the FEC capability is exceeded. The performance of the proposed protocol is analyzed by considering the packet collision probability as well as the bit error probability. The numerical results show that the system throughput is closely related to the bit error rate of the wireless link and the FEC coding rate.
A study on wireless network mac cap considering efficiency of energy in ad-hoc network
Kim, Dong-Il ; Kim, Kwang-Deok ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 200~204
The release of IEEE 802.15.4 PHY-MAC standard represents a milestone in developing of commercial wireless sensor network pursuing low power and low cost. In this paper, IEEE 802.15.4 Medium Access Control (MAC) protocol was analysed at the point of power consumption. This analysis measured the amount of the rest of power after transmitting data with beacon enabled mode and the power consumption of each node in the time period. ns-2 simulation is used to verify the analysis.
A New Backoff algorithm considering Hop Count for the IEEE 802.11 Distributed Coordination Function
Nam, Jae-Hyun ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 205~208
The IEEE 802.11 is a MAC protocol which has been standardized by IEEE for Wireless Local Area Networks (WLANs). In the IEEE 802.11 WLANs, network nodes experiencing collisions on the shared channel need to backoff for a random period of time, which is uniformly selected from the Contention Window (CW). This contention window is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. However, the BEB scheme suffers from a fairness problem; some nodes can achieve significantly larger throughput than others. This paper proposes a new backoff algorithm for the IEEE 802.11 DCF scheme. This algorithm uses the hop count for considering fairness. It causes flows with high hop count to generate short backoff interval than those with low hop count, thus getting high priority. Therefore, when a collision occurs, the modified IEEE 802.11 DCF assigns higher priority to flow to be close to a destination.
Ad hoc Network for Dynamic Multicast Routing Protocol Using ADDMRP
Chi, Sam-Hyun ; Kim, Sung-Uk ; Lee, Kang-Whan ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 209~214
In this paper, we proposed a new MANET (Mobile Ad hoc Networks) technology of routing protocol. The MANET has a mobility formation of mobile nodes in the wireless networks. Wireless network have two types architecture: the Tree based multicast and shared tree based. The two kind's architecture of general wireless networks have difficult to solve the problems existing in the network, such as connectivity, safety, and reliability. For this purpose, as using that ADDMRP (Ad hoc network Doppler effect-based for Dynamic Multicast Routing Protocol), this study gives the following suggestion for new topology through network durability and Omni-directional information. The proposed architectures have considered the mobility location, mobility time, density, velocity and simultaneous using node by Doppler effects and improved the performance.
Reactive Ion Etching of a-Si for high yield and low process cost
Hur, Chang-Wu ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 215~218
In this paper, amorphous semiconductor and insulator thin film are etched using reactive ion etcher. At that time, we experiment in various RIE conditions (chamber pressure, gas flow rate, rf power, temperature) that have effects on quality of thin film. The using gases are
gases. The etching of a-Si:H thin film use
gases and the etching of
thin film use
gas is particularly excellent because the selectivity of between a-Si:H thin film and
thin film is 6:1. We made precise condition on dry etching with uniformity of 5%. If this dry etching condition is used, that process can acquire high yield and can cut down process cost.
Growth of Aluminum Doped Zinc Oxide Films on Polymer Substrates for Flexible Display Applications
Lee, Jae-Hyeong ; Lee, Jong-In ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 219~222
Highly conductive and transparent aluminum doped ZnO thin films (AZO) films have been prepared by r.f. magnetron sputtering processes on poly carbonate (PC) and onto glass as reference. In addition, the electrical, optical properties of the films prepared at various sputtering powers were investigated. The XRD measurements revealed that all of the obtained films were polycrystalline with the hexagonal structure and had a preferred orientation with the c-axis perpendicular to the substrate. The ZnO:Al films were increasingly dark gray colored as the sputter power increased, resulting in the loss of transmittance. High quality films with the resistivity as low as
and transmittance over 90% have been obtained by suitably controlling the r.f. power.
A control of wound-rotor induction generator for random wave input generation system
Kim, Moon-Hwan ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 223~228
This paper deals with the secondary excited induction generator applied to random wave input generation system. As it is preferred to stabilize the output voltage and frequency in the constant level, microcomputer controlled CSI connected to the secondary windings supplies the secondary current with slip frequency. For testing this method, the input torque simulator is constructed, according to the power flow analysis. The experimental and numerical results show the advantage of secondary excited induction generator system for the random input wave generation system.
A New Approach to Estimating the MIMO Channel in Wireless Networks
Kim, Jee-Hoon ; Song, Hyoung-Kyu ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 229~232
This paper investigates on the use of constant-amplitude zero-autocorrelation (CAZAC) sequence for channel estimation in multiple-input multiple-output (MIMO) system over indoor wireless channel. Since the symbol-length of the conventional 4-phase CAZAC sequence is short, there is a limitation to use it for MIMO system in multipath environments. An algorithm which generates longer CAZAC sequences is proposed to overcome that problem. Flexible symbol-length of 4-phase CAZAC sequences can be made by the proposed algorithm. Therefore appropriate symbol-length of CAZAC sequences could be utilized as preambles in accordance with the number of transmit antennas and channel condition. The effect of the number of CAZAC sequences for channel estimation is presented in terms of mean square error (MSE).
Identification of Chinese Event Types Based on Local Feature Selection and Explicit Positive & Negative Feature Combination
Tan, Hongye ; Zhao, Tiejun ; Wang, Haochang ; Hong, Wan-Pyo ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 233~238
An approach to identify Chinese event types is proposed in this paper which combines a good feature selection policy and a Maximum Entropy (ME) model. The approach not only effectively alleviates the problem that classifier performs poorly on the small and difficult types, but improve overall performance. Experiments on the ACE2005 corpus show that performance is satisfying with the 83.5% macro - average F measure. The main characters and ideas of the approach are: (1) Optimal feature set is built for each type according to local feature selection, which fully ensures the performance of each type. (2) Positive and negative features are explicitly discriminated and combined by using one - sided metrics, which makes use of both features' advantages. (3) Wrapper methods are used to search new features and evaluate the various feature subsets to obtain the optimal feature subset.
A Simplified Method to Estimate Travel Cost based on Traffic-Adaptable Heuristics for Accelerating Path Search
Kim, Jin-Deog ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 239~244
In the telematics system, a reasonable path search time should be guaranteed from a great number of user's queries, even though the optimal path with minimized travel time might be continuously changed by the traffic flows. Thus, the path search method should consider traffic flows of the roads and the search time as well. However, the existing path search methods are not able to cope efficiently with the change of the traffic flows and to search rapidly paths simultaneously. This paper proposes a new path search method for fast computation. It also reflects the traffic flows efficiently. Especially, in order to simplify the computation of variable heuristic values, it employs a simplification method for estimating values of traffic-adaptable heuristics. The experiments are carried out with the
algorithm and the proposed method in terms of the execution time, the number of node accesses and the accuracy. The results obtained from the experiments show that the method achieves very fast execution time and the reasonable accuracy as well.
The Audio Signal Classification System Using Contents Based Analysis
Lee, Kwang-Seok ; Kim, Young-Sub ; Han, Hag-Yong ; Hur, Kang-In ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 245~248
In this paper, we research the content-based analysis and classification according to the composition of the feature parameter data base for the audio data to implement the audio data index and searching system. Audio data is classified to the primitive various auditory types. We described the analysis and feature extraction method for the feature parameters available to the audio data classification. And we compose the feature parameters data base in the index group unit, then compare and analyze the audio data centering the including level around and index criterion into the audio categories. Based on this result, we compose feature vectors of audio data according to the classification categories, and simulate to classify using discrimination function.
A Study on Transforming ICT Research Information Service into Semantic Web Environment
Song, Jong-Cheol ; Moon, Byung-Joo ; Jung, Hoe-Kyung ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 249~253
The Research on the ICT(Information & Communication Technology) is proposed the category to IT839 strategy by Government. Government is driving to researching on technology about IT839 Strategy. By transforming this category and research information into Semantic Web environment, it is possible to search function utilizing knowledge base and information object by use of TBox and ABox. In this regard, this study proposes technology for generation of Semantic Web Document about ICT Research Information. The ontology is constructed by using category to IT839 Strategy. The features of framework proposed in this study is to have used a skill to directly map Ontology instance and in case of inability of direct mapping, proposed a skill to establish reliable Semantic Web Document by suggesting indirect mapping skill using mechanical study. In addition, it is possible to establish low cost/high quality Semantic Web Document about ICT research information.
Security and Privacy Aspects of Low-Cost Radio Frequency Identification Systems
Kang, Jin-Suk ; Choi, Yong-Sik ; Sung, Mee-Young ; Shin, Seung-Ho ; Jeong, Tai-Keong T. ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 254~258
Recently, ubiquitous computing in being actively researched and one of the main technology in ubiquitous computing environments is recognized as RFID system. The RFID system has much benefits but simultaneously has some problems such as user's privacy violation. In this paper, in order to improve the survivability of its nodes, it should build available simulation surrounding sensor nodes. Also, In the proposed cryptosystems we use a new hash function for user authentication and a stream cipher based on LFSR(Linear Feedback Shift Register) for message encryption and decryption. Moreover, each algorithm is programmed with C language and simulated on IBM-PC system and we analyze the randomness properties of the proposed algorithms by using statistical tests.
A Mask-based Gaussian Noise Removal Algorithm in Spatial Space
Seo, Hyun-Soo ; Kim, Nam-Ho ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 259~264
According to the development and wide use of broad band internet etc., diverse application technologies using large capacity data such as images have been progressed and in these systems, for accurate acquisition and precise applications of an original signal, the degradation phenomenon generated in the transmission process etc. should be removed. Noises have become known as the main cause of the degradation phenomenon and especially Gaussian noise represents characteristics occurring dependently in image signals and degrades detail information such as edge. In this paper, we removed Gaussian noise using a subdivided nonlinear function according to a threshold value and analyzed the histogram acquired from an edge image to establish a threshold value adaptively, and strengthened detail information of image by using the postprocessing. In simulation results, the proposed method represented excellent performance from comparison of MSE with existing methods.
Mobile Terminated Protocol to Remote Domain Considering User Location Untraceability Service
Kim, Soon-Seok ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 265~268
In previous papers  and , we proposed two improved methods protecting mobile users from active attacks[3,4] of network providers in mobile communication environment. But they were the case that mobile users were located in only home domain. In , we proposed protocol extending the method of  in case of roaming from the home domain to the remote domain. The purpose of this paper is to propose new mobile terminated protocol extending the method of  and analyze its security.
Shortcut Shot Detection Based on Compressed Video Bitstream
Ryu, Kwang-Ryol ; Kim, Young-Bin ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 269~272
The shortcut shot detection based on MPEG compressed video bitstream is presented in this paper. The detection algorithm is used the video picture frame from MPEG compressed video directly not to be decompressed the original image. For shortcut detection, I and P frame of MPEG video bitstream are classified. The changing scene cuts at I pictures are detected by the decompressed DC image and scene cuts at P picture frame by monitoring the percentage of intra-macroblocks per P picture are detected. Experimental results using test video bitstream QVGA results in average 92% detection rate, searching time is taken around 4.5 times faster in comparison with changing scene shot detection algorithm which is decompressed the compressed bitstream.
Compensation of the Distorted 640 Gbps WDM Signals using Optical Phase Conjugator
Lee, Seong-Real ; Lee, Young-Gyo ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 273~280
The numerical methods for finding the optimal parameters in 640 Gbps (16 channels
40 Gbps) WDM system with optical phase conjugator (OPC) are proposed, which effectively compensate the distorted overall WDM channels. The considered optimal parameters are the OPC position and the dispersion coefficient of fibers. The numerical approaches are accomplished through two different procedures. One of these procedures is that the optimal OPC position is previously searched and then the optimal dispersion coefficient is searched at the obtained optimal OPC position. The other is the reverse of the above procedure. From the numerical results, it is confirmed that two optimal parameters depend on each other, but less related with the searching procedure. The methods proposed in this research will be expected to alternate with the method of making a symmetrical distribution of power and local dispersion in real optical link which is a serious problem of applying the OPC into multi-channels WDM system.
Analyses of Short Pulse Generation Using Heterodyne Techniques
Kim, Jung-Tae ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 281~284
We have analyzed the short pulse generation using heterodyne techniques. The numerical model for semiconductor lasers under the heterodyne technique is based on the Lang's equation and has been extended in order to take into account the simultaneous injection of the multiple sidebands of the current-modulated laser. The unselected sidebands will affect the optical and RF-spectral characteristics even when the semiconductor laser is locked to the target sidebands.
Implementation of PDP Driving Circuit for AC-Type
Jang, Yun-Seok ; Choi, Jin-Ho ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 285~288
PDP(Plasma Display Panel) driving circuit requires switching devices and capacitors to stand up high voltages over 150volts. Thereby the power consumption and the cost of a PDP driving circuit increase. In this paper, a PDP driving circuit is proposed that can be operated with a lower supply voltage than the supply voltage of conventional driving circuit. The operation of the proposed driving circuit is verified by the computer simulation and experiments. PSPICE simulation and experiments results show that the output signal can drive PDP cells when the supply voltage is higher than 40volts.
A Study on s-INS for Small and Medium-Sized Ships
Park, Nam-Kyu ; Kim, Joo-Young ; Kim, Woo-Chul ;
Journal of information and communication convergence engineering, volume 5, issue 3, 2007, Pages 289~294
With regard to a marine safety system, large vessels are generally loaded with INS (Integrated Navigation System). But although small and medium-sized ships are exposed to safety accidents in the sea, they are not carrying proper navigation devices and equipment. Accordingly, in order to develop INS for small and medium-sized ships(s-INS), an existing INS has newly been organized and integrated. Recently, more strict enforcement of INS-related regulations is expected at home and abroad, and the scope of their applications is being broadened. To keep up with this global trend that ships are being loaded with digital devices and equipment, this study has tried to develop s-INS, broadening its applications, and suggesting a future research plan.