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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Electronics and Telecommunications Research Institute
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Volume & Issues
Volume 29, Issue 6 - Dec 2007
Volume 29, Issue 5 - Oct 2007
Volume 29, Issue 4 - Aug 2007
Volume 29, Issue 3 - Jun 2007
Volume 29, Issue 2 - Apr 2007
Volume 29, Issue 1 - Feb 2007
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UbiFOS: A Small Real-Time Operating System for Embedded Systems
Ahn, Hee-Joong ; Cho, Moon-Haeng ; Jung, Myoung-Jo ; Kim, Yong-Hee ; Kim, Joo-Man ; Lee, Cheol-Hoon ;
ETRI Journal, volume 29, issue 3, 2007, Pages 259~269
The ubiquitous flexible operating system (UbiFOS) is a real-time operating system designed for cost-conscious, low-power, small to medium-sized embedded systems such as cellular phones, MP3 players, and wearable computers. It offers efficient real-time operating system services like multi-task scheduling, memory management, inter-task communication and synchronization, and timers while keeping the kernel size to just a few to tens of kilobytes. For flexibility, UbiFOS uses various task scheduling policies such as cyclic time-slice (round-robin), priority-based preemption with round-robin, priority-based preemptive, and bitmap. When there are less than 64 tasks, bitmap scheduling is the best policy. The scheduling overhead is under 9
on the ARM926EJ processor. UbiFOS also provides the flexibility for user to select from several inter-task communication techniques according to their applications. We ported UbiFOS on the ARM9-based DVD player (20 kB), the Calm16-based MP3 player (under 7 kB), and the ATmega128-based ubiquitous sensor node (under 6 kB). Also, we adopted the dynamic power management (DPM) scheme. Comparative experimental results show that UbiFOS could save energy up to 30% using DPM.
Kernel Thread Scheduling in Real-Time Linux for Wearable Computers
Kang, Dong-Wook ; Lee, Woo-Joong ; Park, Chan-Ik ;
ETRI Journal, volume 29, issue 3, 2007, Pages 270~280
In Linux, real-time tasks are supported by separating real-time task priorities from non-real-time task priorities. However, this separation of priority ranges may not be effective when real-time tasks make the system calls that are taken care of by the kernel threads. Thus, Linux is considered a soft real-time system. Moreover, kernel threads are configured to have static priorities for throughputs. The static assignment of priorities to kernel threads causes trouble for real-time tasks when real-time tasks require kernel threads to be invoked to handle the system calls because kernel threads do not discriminate between real-time and non-real-time tasks. We present a dynamic kernel thread scheduling mechanism with weighted average priority inheritance protocol (PIP), a variation of the PIP. The scheduling algorithm assigns proper priorities to kernel threads at runtime by monitoring the activities of user-level real-time tasks. Experimental results show that the algorithms can greatly improve the unexpected execution latency of real-time tasks.
PosCFS+: A Self-Managed File Service in Personal Area Network
Lee, Woo-Joong ; Kim, Shi-Ne ; Park, Chan-Ik ;
ETRI Journal, volume 29, issue 3, 2007, Pages 281~291
Wearable computers consisting of various small devices such as smart phones, digital cameras, MP3 players and specialized I/O devices in personal area networks will play an important role in future ubiquitous computing. In this environment, accessing user data is quite complex due to the dynamic and heterogeneous characteristics of the underlying networks. Moreover, since the amount of user data increases rapidly, automatic data backup management is also critical. To overcome these challenges, several studies have been conducted including our previously proposed file service system, PosCFS, which could be adapted to the requirements with a virtualization technique allowing per-user global namespace for managing and accessing data stored on physical storage spaces detected in PAN. In this paper, we present a smart file service framework, PosCFS+ which is an improved and extended version of our previous work. Performance improvement is made possible by redesigning the metadata management scheme based on database and keywords rather than ontology. In addition, the automatic data replication management is newly designed based on the OSD protocol.
Development of an Optimized Feature Extraction Algorithm for Throat Signal Analysis
Jung, Young-Giu ; Han, Mun-Sung ; Lee, Sang-Jo ;
ETRI Journal, volume 29, issue 3, 2007, Pages 292~299
In this paper, we present a speech recognition system using a throat microphone. The use of this kind of microphone minimizes the impact of environmental noise. Due to the absence of high frequencies and the partial loss of formant frequencies, previous systems using throat microphones have shown a lower recognition rate than systems which use standard microphones. To develop a high performance automatic speech recognition (ASR) system using only a throat microphone, we propose two methods. First, based on Korean phonological feature theory and a detailed throat signal analysis, we show that it is possible to develop an ASR system using only a throat microphone, and propose conditions of the feature extraction algorithm. Second, we optimize the zero-crossing with peak amplitude (ZCPA) algorithm to guarantee the high performance of the ASR system using only a throat microphone. For ZCPA optimization, we propose an intensification of the formant frequencies and a selection of cochlear filters. Experimental results show that this system yields a performance improvement of about 4% and a reduction in time complexity of 25% when compared to the performance of a standard ZCPA algorithm on throat microphone signals.
Adaptive Channel Normalization Based on Infomax Algorithm for Robust Speech Recognition
Jung, Ho-Young ;
ETRI Journal, volume 29, issue 3, 2007, Pages 300~304
This paper proposes a new data-driven method for high-pass approaches, which suppresses slow-varying noise components. Conventional high-pass approaches are based on the idea of decorrelating the feature vector sequence, and are trying for adaptability to various conditions. The proposed method is based on temporal local decorrelation using the information-maximization theory for each utterance. This is performed on an utterance-by-utterance basis, which provides an adaptive channel normalization filter for each condition. The performance of the proposed method is evaluated by isolated-word recognition experiments with channel distortion. Experimental results show that the proposed method yields outstanding improvement for channel-distorted speech recognition.
Stereo-Vision-Based Human-Computer Interaction with Tactile Stimulation
Yong, Ho-Joong ; Back, Jong-Won ; Jang, Tae-Jeong ;
ETRI Journal, volume 29, issue 3, 2007, Pages 305~310
If a virtual object in a virtual environment represented by a stereo vision system could be touched by a user with some tactile feeling on his/her fingertip, the sense of reality would be heightened. To create a visual impression as if the user were directly pointing to a desired point on a virtual object with his/her own finger, we need to align virtual space coordinates and physical space coordinates. Also, if there is no tactile feeling when the user touches a virtual object, the virtual object would seem to be a ghost. Therefore, a haptic interface device is required to give some tactile sensation to the user. We have constructed such a human-computer interaction system in the form of a simple virtual reality game using a stereo vision system, a vibro-tactile device module, and two position/orientation sensors.
User-Centric Conflict Management for Media Services Using Personal Companions
Shin, Choon-Sung ; Yoon, Hyo-Seok ; Woo, Woon-Tack ;
ETRI Journal, volume 29, issue 3, 2007, Pages 311~321
In this paper, we propose a user-centric conflict management method for media services which exploits personal companions for the harmonious detection and resolution of service conflicts. To detect conflicts based on the varying characteristics of individual users, the proposed method exploits the unified context describing all users attempting to access media services. It recommends and mediates users' preferred media contents through a shared screen and personal companions to resolve the detected conflicts. During the recommendation, a list of preferred media contents is displayed on the shared screen, and a personally preferred content list is shown on the user's personal companion comprising the selection of media contents. Mediation assists the selection of a consensual service by gathering the users' selections and highlighting the common media contents. In experiments carried out in a ubiHome, we observed that recommendations and mediation are useful in harmoniously resolving conflicts by encouraging user participation in conflict situations.
DS-PAM UWB System Using Non-linear Chirp Waveform
Shen, Hanbing ; Zhang, Weihua ; An, Xizhi ; Kwak, Kyung-Sup ;
ETRI Journal, volume 29, issue 3, 2007, Pages 322~328
We propose a direct-sequence pulse-amplitude modulation (DS-PAM) ultra-wideband (UWB) system which employs a non-linear chirp waveform instead of the conventional Gaussian monocycle in this paper. In the approved frequency for UWB, there exist myriad narrowband interferers. Specifically, we focus on the mutual interference between UWB systems and 802.11a WLAN. This paper offers a method to suppress this in-band narrowband interference by introducing a kind of non-linear chirp waveform. Using the proposed non-linear chirp waveform, the effects of one or more narrowband interference sources with different frequencies can be suppressed. System performance of UWB systems in the narrowband interference environment can be improved. Computer simulations with additive white Gaussian noise successfully demonstrate an increase in performance with the proposed system as compared to traditional linear chirp systems.
A Real-Time Algorithm for Timeslot Assignment in ISM System with DVB-RCS
Lee, Ik-Sun ; Sung, Chang-Sup ; Jin, Gwang-Ja ; Han, Ki-Seop ;
ETRI Journal, volume 29, issue 3, 2007, Pages 329~335
This paper considers a timeslot assignment problem in an interactive satellite multimedia (ISM) system with digital video broadcast-return channel via satellite (DVB-RCS). The timeslot assignment problem is formulated as a binary integer programming to maximize the overall weighted throughput and is shown to be NP-hard. Thus, three real-time heuristic algorithms including ratio-based, packet-size (PS)-based, and transmission gain (TG)-based are derived, and some computational experiments are made. Considering the results, the ratio-based heuristic algorithm is demonstrated to be the most effective and efficient. We propose adapting the ratio-based heuristic algorithm to the timeslot assignment problem to greatly improve the ISM system utilization.
WIS: Weighted Interesting Sequential Pattern Mining with a Similar Level of Support and/or Weight
Yun, Un-Il ;
ETRI Journal, volume 29, issue 3, 2007, Pages 336~352
Sequential pattern mining has become an essential task with broad applications. Most sequential pattern mining algorithms use a minimum support threshold to prune the combinatorial search space. This strategy provides basic pruning; however, it cannot mine correlated sequential patterns with similar support and/or weight levels. If the minimum support is low, many spurious patterns having items with different support levels are found; if the minimum support is high, meaningful sequential patterns with low support levels may be missed. We present a new algorithm, weighted interesting sequential (WIS) pattern mining based on a pattern growth method in which new measures, sequential s-confidence and w-confidence, are suggested. Using these measures, weighted interesting sequential patterns with similar levels of support and/or weight are mined. The WIS algorithm gives a balance between the measures of support and weight, and considers correlation between items within sequential patterns. A performance analysis shows that WIS is efficient and scalable in weighted sequential pattern mining.
Fast Extraction of Objects of Interest from Images with Low Depth of Field
Kim, Chang-Ick ; Park, Jung-Woo ; Lee, Jae-Ho ; Hwang, Jenq-Neng ;
ETRI Journal, volume 29, issue 3, 2007, Pages 353~362
In this paper, we propose a novel unsupervised video object extraction algorithm for individual images or image sequences with low depth of field (DOF). Low DOF is a popular photographic technique which enables the representation of the photographer's intention by giving a clear focus only on an object of interest (OOI). We first describe a fast and efficient scheme for extracting OOIs from individual low-DOF images and then extend it to deal with image sequences with low DOF in the next part. The basic algorithm unfolds into three modules. In the first module, a higher-order statistics map, which represents the spatial distribution of the high-frequency components, is obtained from an input low-DOF image. The second module locates the block-based OOI for further processing. Using the block-based OOI, the final OOI is obtained with pixel-level accuracy. We also present an algorithm to extend the extraction scheme to image sequences with low DOF. The proposed system does not require any user assistance to determine the initial OOI. This is possible due to the use of low-DOF images. The experimental results indicate that the proposed algorithm can serve as an effective tool for applications, such as 2D to 3D and photo-realistic video scene generation.
An FPGA Implementation of High-Speed Flexible 27-Mbps 8-StateTurbo Decoder
Choi, Duk-Gun ; Kim, Min-Hyuk ; Jeong, Jin-Hee ; Jung, Ji-Won ; Bae, Jong-Tae ; Choi, Seok-Soon ; Yun, Young ;
ETRI Journal, volume 29, issue 3, 2007, Pages 363~370
In this paper, we propose a flexible turbo decoding algorithm for a high order modulation scheme that uses a standard half-rate turbo decoder designed for binary quadrature phase-shift keying (B/QPSK) modulation. A transformation applied to the incoming I-channel and Q-channel symbols allows the use of an off-the-shelf B/QPSK turbo decoder without any modifications. Iterative codes such as turbo codes process the received symbols recursively to improve performance. As the number of iterations increases, the execution time and power consumption also increase. The proposed algorithm reduces the latency and power consumption by combination of the radix-4, dual-path processing, parallel decoding, and early-stop algorithms. We implement the proposed scheme on a field-programmable gate array and compare its decoding speed with that of a conventional decoder. The results show that the proposed flexible decoding algorithm is 6.4 times faster than the conventional scheme.
A New Automatic Compensation Network for System-on-Chip Transceivers
Ryu, Jee-Youl ; Noh, Seok-Ho ;
ETRI Journal, volume 29, issue 3, 2007, Pages 371~380
This paper proposes a new automatic compensation network (ACN) for a system-on-chip (SoC) transceiver. We built a 5 GHz low noise amplifier (LNA) with an on-chip ACN using 0.18
SiGe technology. This network is extremely useful for today's radio frequency (RF) integrated circuit devices in a complete RF transceiver environment. The network comprises an RF design-for-testability (DFT) circuit, capacitor mirror banks, and a digital signal processor. The RF DFT circuit consists of a test amplifier and RF peak detectors. The RF DFT circuit helps the network to provide DC output voltages, which makes the compensation network automatic. The proposed technique utilizes output DC voltage measurements and these measured values are translated into the LNA specifications such as input impedance, gain, and noise figure using the developed mathematical equations. The ACN automatically adjusts the performance of the 5 GHz LNA with the processor in the SoC transceiver when the LNA goes out of the normal range of operation. The ACN compensates abnormal operation due to unusual thermal variation or unusual process variation. The ACN is simple, inexpensive and suitable for a complete RF transceiver environment.
Design of Quasi-Cyclic Low-Density Parity Check Codes with Large Girth
Jing, Long-Jiang ; Lin, Jing-Li ; Zhu, Wei-Le ;
ETRI Journal, volume 29, issue 3, 2007, Pages 381~389
In this paper we propose a graph-theoretic method based on linear congruence for constructing low-density parity check (LDPC) codes. In this method, we design a connection graph with three kinds of special paths to ensure that the Tanner graph of the parity check matrix mapped from the connection graph is without short cycles. The new construction method results in a class of (3,
)-regular quasi-cyclic LDPC codes with a girth of 12. Based on the structure of the parity check matrix, the lower bound on the minimum distance of the codes is found. The simulation studies of several proposed LDPC codes demonstrate powerful bit-error-rate performance with iterative decoding in additive white Gaussian noise channels.
Error Concealment Using Inter-layer Correlation for Scalable Video Coding
Park, Chun-Su ; Wang, Tae-Shick ; Ko, Sung-Jea ;
ETRI Journal, volume 29, issue 3, 2007, Pages 390~392
In this paper, we propose a new error concealment (EC) method using inter-layer correlation for scalable video coding. In the proposed method, the auxiliary motion vector (MV) and the auxiliary mode number (MN) of intra prediction are interleaved into the bitstream to recover the corrupted frame. In order to reduce the bit rate, the proposed method encodes the difference between the original and the predicted values of the MV and MN instead of the original values. Experimental results show that the proposed EC outperforms the conventional EC by 2.8 dB to 6.7 dB.
Protection of Digital TV from Cognitive Radio Interference
Yoon, Young-Keun ; Hong, Heon-Jin ; Choi, Ik-Guen ;
ETRI Journal, volume 29, issue 3, 2007, Pages 393~395
Analytic modeling and computational simulation for the protection of DTV from cognitive radio interference are performed. Protection is achieved by using the protection ratio, which is derived through system modeling and its analysis. On the frequency coordination between digital TV and cognitive radio, an analysis in a co-channel environment, in a rural area in Korea, is performed.
A Novel High Performance Architecture for H.264/AVC Deblocking Filtering
Lopez, Sebastian ; Tobajas, Felix ; Callico, Gustavo M. ; Perez, Pedro A. ; De Armas, Valentin ; Lopez, Jose F. ; Sarmiento, Roberto ;
ETRI Journal, volume 29, issue 3, 2007, Pages 396~398
This letter presents an architecture based on a new double-filter strategy to perform the adaptive in-loop filtering process specified by the H.264/AVC standard. The proposed architecture shows considerable advantages, both in terms of hardware cost and latency, when compared with the approaches found in the most recent literature.
A Novel and Efficient Feature Extraction Method for Iris Recognition
Ko, Jong-Gook ; Gil, Youn-Hee ; Yoo, Jang-Hee ; Chung, Kyo-Il ;
ETRI Journal, volume 29, issue 3, 2007, Pages 399~401
With a growing emphasis on human identification, iris recognition has recently received increasing attention. Iris recognition includes eye imaging, iris segmentation, verification, and so on. In this letter, we propose a novel and efficient iris recognition method which employs a cumulative-sum-based grey change analysis. Experimental results demonstrate that the proposed method can be used for human identification in efficient manner.
RBF Neural Network Based SLM Peak-to-Average Power Ratio Reduction in OFDM Systems
Sohn, In-Soo ;
ETRI Journal, volume 29, issue 3, 2007, Pages 402~404
One of the major disadvantages of the orthogonal frequency division multiplexing system is high peak-to-average power ratio (PAPR). Selected mapping (SLM) is an efficient distortionless PAPR reduction scheme which selects the minimum PAPR sequence from a group of independent phase rotated sequences. However, the SLM requires explicit side information and a large number of IFFT operations. In this letter we investigate a novel PAPR reduction method based on the radial basis function network and SLM.
A Novel Globally Adaptive Load-Balanced Routing Algorithm for Torus Interconnection Networks
Wang, Hong ; Xu, Du ; Li, Lemin ;
ETRI Journal, volume 29, issue 3, 2007, Pages 405~407
A globally adaptive load-balanced routing algorithm for torus interconnection networks is proposed. Unlike previously published algorithms, this algorithm employs a new scheme based on collision detection to handle deadlock, and has higher routing adaptability than previous algorithms. Simulation results show that our algorithm outperforms previous algorithms by 16% on benign traffic patterns, and by 10% to 21% on adversarial traffic patterns.
A 9-Bit 80-MS/s CMOS Pipelined Folding A/D Converter with an Offset Canceling Technique
Lee, Seung-Chul ; Jeon, Young-Deuk ; Kwon, Jong-Kee ;
ETRI Journal, volume 29, issue 3, 2007, Pages 408~410
A 9-bit 80-MS/s CMOS pipelined folding analog-to-digital converter employing offset-canceled preamplifiers and a subranging scheme is proposed to extend the resolution of a folding architecture. A fully differential dc-decoupled structure achieves high linearity in circuit design. The measured differential nonlinearity and integral nonlinearity of the prototype are