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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 28, Issue 6 - Dec 2006
Volume 28, Issue 5 - Oct 2006
Volume 28, Issue 4 - Aug 2006
Volume 28, Issue 3 - Jun 2006
Volume 28, Issue 2 - Apr 2006
Volume 28, Issue 1 - Feb 2006
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View-Dependent Adaptive Animation of Liquids
Kim, Jang-Hee ; Ihm, In-Sung ; Cha, Deuk-Hyun ;
ETRI Journal, volume 28, issue 6, 2006, Pages 697~708
Various adaptive mesh refinement techniques are often employed in numerical simulations for increasing spatial and temporal resolution beyond the limits imposed by available CPU time and memory space. Recently, an octree-based adaptive mesh structure was successfully used in fluid animation to place more grid cells efficiently in visually interesting regions of fluids. In an attempt to optimize the use of computational resources further in fluid animation, this paper extends this adaptive technique by modifying the mesh refinement scheme so that the camera's viewing properties are dynamically exploited during the simulation. Based on a simple adaptive mesh structure, we show that the new meshing strategy can save a substantial amount of computation time and memory space by using a view-dependent adaptive approach. The experimental results reveal that the proposed technique provides a good compromise between the computational effort and the simulation's fidelity, and may be used quite effectively in 3D animation production.
A Simple and Efficient One-to-Many Large File Distribution Method Exploiting Asynchronous Joins
Lee, Soo-Jeon ; Kang, Kyung-Ran ; Lee, Dong-Man ; Kim, Jae-Hoon ;
ETRI Journal, volume 28, issue 6, 2006, Pages 709~720
In this paper, we suggest a simple and efficient multiple-forwarder-based file distribution method which can work with a tree-based application layer multicast. Existing multiple-forwarder approaches require high control overhead. The proposed method exploits the assumption that receivers join a session at different times. In tree-based application layer multicast, a set of data packets is delivered from its parent after a receiver has joined but before the next receiver joins without overlapping that of other receivers. The proposed method selects forwarders from among the preceding receivers and the forwarder forwards data packets from the non-overlapping data packet set. Three variations of forwarder selection algorithms are proposed. The impact of the proposed algorithms is evaluated using numerical analysis. A performance evaluation using PlanetLab, a global area overlay testbed, shows that the proposed method enhances throughput while maintaining the data packet duplication ratio and control overhead significantly lower than the existing method, Bullet.
A Fast Intra Skip Detection Algorithm for H.264/AVC Video Encoding
Kim, Byung-Gyu ; Kim, Jong-Ho ; Cho, Chang-Sik ;
ETRI Journal, volume 28, issue 6, 2006, Pages 721~731
A fast intra skip detection algorithm based on the ratedistortion (RD) cost for an inter frame (P-slices) is proposed for H.264/AVC video encoding. In the H.264/AVC coding standard, a robust rate-distortion optimization technique is used to select the best coding mode and reference frame for each macroblock (MB). There are three types of intra predictions according to profiles. These are
intra predictions for luminance and an
intra prediction for chroma. For the high profile, an
intra prediction has been added for luminance. The
prediction mode has 9 prediction directions with 4 directions for
chrominance. In addition to the inter mode search procedure, an intra mode search causes a significant increase in the complexity and computational load for an inter frame. To reduce the computational load of the intra mode search at the inter frame, the RD costs of the neighborhood MBs for the current MB are used and we propose an adaptive thresholding scheme for the intra skip extraction. We verified the performance of the proposed scheme through comparative analysis of experimental results using joint model reference software. The overall encoding time was reduced up to 32% for the IPPP sequence type and 35% for the IBBPBBP sequence type.
Novel Low-Power High-dB Range CMOS Pseudo-Exponential Cells
De La Cruz Blas, Carlos A. ; Lopez-Martin, Antonio ;
ETRI Journal, volume 28, issue 6, 2006, Pages 732~738
In this paper, novel CMOS pseudo-exponential circuits operating in a class-AB mode are presented. The pseudo-exponential approximation employed is based on second order equations. Such terms are derived in a straightforward way from the inherent nonlinear currents of class-AB transconductors. The cells are appropriate to be integrated in portable equipment due to their compactness and very low power consumption. Measurement results from a fabricated prototype in a 0.5
technology reveal a range of 45 dB with errors lower than
dB, a power consumption of 100
, and an area of 0.01
Optimization of Thermo-Optic Parameters for Temperature-Insensitive LPWG Refractometers
Lee, Dong-Seok ; Kim, Kyong-Hon ; Hwang, Seok-Hyun ; Lee, Min-Hee ; Lee, El-Hang ;
ETRI Journal, volume 28, issue 6, 2006, Pages 739~744
In this paper, we report numerically calculated results of testing a temperature-insensitive refractive sensor based on a planar-type long-period waveguide grating (LPWG). The LPWG consists of properly chosen polymer materials with an optimized thermo-optic coefficient for the core layer in a four-layer waveguide structure. The resonant wavelength shift below the spectral resolution of the conventional optical spectrum analyzer is obtained accurately over a temperature change of
even without any temperature control. The refractive index sensitivity of the proposed grating scheme is about 0.004 per resonant wavelength shift of 0.1 nm for an optimized thermo-optic coefficient.
A Method for Distinguishing the Two Candidate Elliptic Curves in the Complex Multiplication Method
Nogami, Yasuyuki ; Obara, Mayumi ; Morikawa, Yoshitaka ;
ETRI Journal, volume 28, issue 6, 2006, Pages 745~760
In this paper, we particularly deal with no
-rational two-torsion elliptic curves, where
is the prime field of the characteristic p. First we introduce a shift product-based polynomial transform. Then, we show that the parities of (#E - 1)/2 and (#E' - 1)/2 are reciprocal to each other, where #E and #E' are the orders of the two candidate curves obtained at the last step of complex multiplication (CM)-based algorithm. Based on this property, we propose a method to check the parity by using the shift product-based polynomial transform. For a 160 bits prime number as the characteristic, the proposed method carries out the parity check 25 or more times faster than the conventional checking method when 4 divides the characteristic minus 1. Finally, this paper shows that the proposed method can make CM-based algorithm that looks up a table of precomputed class polynomials more than 10 percent faster.
Efficiency Evaluation of the Unconditional Maximum Likelihood Estimator for Near-Field DOA Estimation
Arceo-Olague, J.G. ; Covarrubias-Rosales, D.H. ; Luna-Rivera, J.M. ;
ETRI Journal, volume 28, issue 6, 2006, Pages 761~769
In this paper, we address the problem of closely spaced source localization using sensor array processing. In particular, the performance efficiency (measured in terms of the root mean square error) of the unconditional maximum likelihood (UML) algorithm for estimating the direction of arrival (DOA) of near-field sources is evaluated. Four parameters are considered in this evaluation: angular separation among sources, signal-to-noise ratio (SNR), number of snapshots, and number of sources (multiple sources). Simulations are conducted to illustrate the UML performance to compute the DOA of sources in the near-field. Finally, results are also presented that compare the performance of the UML DOA estimator with the existing multiple signal classification approach. The results show the capability of the UML estimator for estimating the DOA when the angular separation is taken into account as a critical parameter. These results are consistent in both low SNR and multiple-source scenarios.
Hyperspectral Fluorescence Imaging for Mouse Skin Tumor Detection
Kong, Seong G. ; Martin, Matthew E. ; Vo-Dinh, Tuan ;
ETRI Journal, volume 28, issue 6, 2006, Pages 770~776
This paper presents a hyperspectral imaging technique based on laser-induced fluorescence for non-invasive detection of tumorous tissue on mouse skin. Hyperspectral imaging sensors collect image data in a number of narrow, adjacent spectral bands. Such high-resolution measurement of spectral information reveals contiguous emission spectra at each image pixel useful for the characterization of constituent materials. The hyperspectral image data used in this study are fluorescence images of mouse skin consisting of 21 spectral bands in the visible spectrum of the wavelengths ranging from 440 nm to 640 nm. Fluorescence signal is measured with the use of laser excitation at 337 nm. An acousto-optic tunable filter (AOTF) is used to capture images at 10 nm intervals. All spectral band images are spatially registered with the reference band image at 490 nm to obtain exact pixel correspondences by compensating the spatial offsets caused by the refraction differences in AOTF at different wavelengths during the image capture procedure. The unique fluorescence spectral signatures demonstrate a good separation to differentiate malignant tumors from normal tissues for rapid detection of skin cancers without biopsy.
The Criteria, Procedure, and Classification of Traffic-Sensitive and Non-Traffic-Sensitive Components: A Case of CDMA Mobile System
Kim, Moon-Soo ;
ETRI Journal, volume 28, issue 6, 2006, Pages 777~786
Since the introduction of competition in the telecommunication market due to the growth of the interconnection between heterogeneous networks, particularly fixed and mobile networks, the interconnection charge based on traffic-sensitive (TS) and non-traffic-sensitive (NTS) costs has become more important. Although there have been many studies of the public switched telephone network (PSTN), previous studies of TS and NTS costs in mobile networks are very few. In this paper, as a pilot study, we propose three criteria and a procedure for the classification of TS and NTS costs based on mobile systems. The three criteria are the following: function type, investment requirement, and main exhaust driver. Moreover, for a CDMA mobile system, strongly TS, strongly NTS, and mixed components are classified by the proposed criteria and procedure. The proposed criteria, procedure, and classification can provide a systematic and useful guideline to decide the scope of mobile facilities and to determine the terminating cost on mobile networks from fixed networks.
Vertically Well-Aligned ZnO Nanowires on c-
and GaN Substrates by Au Catalyst
Park, Hyun-Kyu ; Oh, Myung-Hoon ; Kim, Sang-Woo ; Kim, Gil-Ho ; Youn, Doo-Hyeob ; Lee, Sun-Young ; Kim, Sang-Hyeob ; Kim, Ki-Chul ; Maeng, Sung-Lyul ;
ETRI Journal, volume 28, issue 6, 2006, Pages 787~789
In this letter, we report that vertically well-aligned ZnO nanowires were grown on GaN epilayers and c-plane sapphire via a vapor-liquid-solid process by introducing a 3 nm Au thin film as a catalyst. In our experiments, epitaxially grown ZnO nanowires on Au-coated GaN were vertically well-aligned, while nanowires normally tilted from the surface when grown on Au-coated c-
substrates. However, pre-growth annealing of the Au thin layer on c-
resulted in the growth of well-aligned nanowires in a normal surface direction. High-resolution transmission electron microscopy measurements showed that the grown nanowires have a hexagonal c-axis orientation with a single-crystalline structure.
A Simple Efficient Stopping Criterion for Turbo Decoder
Kim, Young-Sup ; Ra, Sung-Woong ;
ETRI Journal, volume 28, issue 6, 2006, Pages 790~792
The performance of a turbo decoder depends strongly on the number of iterations in its decoding process. It is necessary to stop the decoding process at an appropriate moment to alleviate the serious burden, in terms of both the computational speed and latency, part of which is associated with too many iterations. In this letter, we introduce a criterion for finding the opportune moment to stop the decoding process, called a hard decision aided criterion based on bit interleaved parity, which is known to have much simpler hardware logic, compared with other schemes, and does not lead to any significant performance degradation.
Computing the Average Symbol Error Probability of the MPSK System Having Quadrature Error
Park, Seung-Keun ; Cho, Sung-Ho ;
ETRI Journal, volume 28, issue 6, 2006, Pages 793~795
When quadrature error exists, the shape of the M-ary phase shift keying (MPSK) signal constellation becomes skewed-elliptic. Each MPSK symbol takes on a different symbol error probability (SEP) value. The analytical results presented thus far have been derived from studies which examined the SEP problem assuming that the SEP of each MPSK symbol is equally likely; therefore, those results should not be treated as offering a complete solution. In this letter, we present a new and more complete solution to the SEP problem of MPSK by relaxing the above assumption and finding the expressions for the average as well as individual SEP in the presence of quadrature error.
Improvement of Communication Reliability of Small UAV by a Tapered Stacked Antenna
Kim, Duck-Hwan ; Lee, Kyu-Hwan ; Kim, Young-Sik ;
ETRI Journal, volume 28, issue 6, 2006, Pages 796~798
This letter proposes a tapered stacked microstrip antenna for application in small unmanned aerial vehicles (UAVs), which has advantages in mountainous terrains. With its tapered structure and increased bandwidth designed to operate at the resonance frequency of 2.4 GHz, the proposed antenna improves directivity, accuracy, and precision of small UAVs. The test flight results show the proposed tapered antenna has a three times higher impedance capability of 350 MHz based on VSWR<2. The transmission pattern is also more reliable than that of previous antenna designs.
Mobility Influences on the Capacity of Wireless Cellular Networks
Zhang, Yide ; Li, Lemin ; Li, Bo ;
ETRI Journal, volume 28, issue 6, 2006, Pages 799~802
Capacity has always been a major concern in wireless networks. This letter studies the impact of mobility on the overall system capacity in wireless cellular networks. In this letter, we present a simple system model which we developed to capture the inherent relationships among system capacity, new call blocking probability, handoff dropping probability, call terminating probability, and bandwidth utilization rate. We investigate the complex relationship between mobility and capacity-related parameters. Through simulation, we demonstrate that mobility has a significant impact on capacity and is reversely proportional to the bandwidth reserved for handoff traffic.
Structural Disambiguation of Korean Adverbs Based on Correlative Relation and Morphological Context
Seo, Young-Ae ; Park, Sang-Kyu ; Choi, Key-Sun ;
ETRI Journal, volume 28, issue 6, 2006, Pages 803~806
This letter addresses a structural disambiguation method for Korean adverbs based on the correlative relation constraints between adverbs and modifiees, and the morphological context information of sentences. Using the proposed method, we improved the dependency parsing accuracy of adverbs from 79.2 to 89%. The experimental result shows that the proposed method is especially expert in parsing adverbs which can modify multiple word classes or have a long distance dependency relation to their modifiees.
Modality-Based Sentence-Final Intonation Prediction for Korean Conversational-Style Text-to-Speech Systems
Oh, Seung-Shin ; Kim, Sang-Hun ;
ETRI Journal, volume 28, issue 6, 2006, Pages 807~810
This letter presents a prediction model for sentence-final intonations for Korean conversational-style text-to-speech systems in which we introduce the linguistic feature of 'modality' as a new parameter. Based on their function and meaning, we classify tonal forms in speech data into tone types meaningful for speech synthesis and use the result of this classification to build our prediction model using a tree structured classification algorithm. In order to show that modality is more effective for the prediction model than features such as sentence type or speech act, an experiment is performed on a test set of 970 utterances with a training set of 3,883 utterances. The results show that modality makes a higher contribution to the determination of sentence-final intonation than sentence type or speech act, and that prediction accuracy improves up to 25% when the feature of modality is introduced.
Impostor Detection in Speaker Recognition Using Confusion-Based Confidence Measures
Kim, Kyu-Hong ; Kim, Hoi-Rin ; Hahn, Min-Soo ;
ETRI Journal, volume 28, issue 6, 2006, Pages 811~814
In this letter, we introduce confusion-based confidence measures for detecting an impostor in speaker recognition, which does not require an alternative hypothesis. Most traditional speaker verification methods are based on a hypothesis test, and their performance depends on the robustness of an alternative hypothesis. Compared with the conventional Gaussian mixture model-universal background model (GMM-UBM) scheme, our confusion-based measures show better performance in noise-corrupted speech. The additional computational requirements for our methods are negligible when used to detect or reject impostors.
Performance Analysis of an Adaptive Link Status Update Scheme Based on Link-Usage Statistics for QoS Routing
Yang, Mi-Jeong ; Kim, Tae-Il ; Jung, Hae-Won ; Jung, Myoung-Hee ; Choi, Seung-Hyuk ; Chung, Min-Young ; Park, Jae-Hyung ;
ETRI Journal, volume 28, issue 6, 2006, Pages 815~818
In the global Internet, a constraint-based routing algorithm performs the function of selecting a routing path while satisfying some given constraints rather than selecting the shortest path based on physical topology. It is necessary for constraint-based routing to disseminate and update link state information. The triggering policy of link state updates significantly affects the volume of update traffic and the quality of services (QoS). In this letter, we propose an adaptive triggering policy based on link-usage statistics in order to reduce the volume of link state update traffic without deterioration of QoS. Also, we evaluate the performance of the proposed policy via simulations.
Log-Polar Coordinate Image Space for the Efficient Detection of Vanishing Points
Seo, Kyung-Seok ; Park, Chang-Joon ; Choi, Heung-Moon ;
ETRI Journal, volume 28, issue 6, 2006, Pages 819~821
Log-polar coordinate image space is proposed as a solution for the problem of unbounded accumulator space in the automatic detection of vanishing points. The proposed method can detect vanishing points at high speed under small memory requirements, as opposed to conventional image space based methods.
Time-Varying Multipath Channel Estimation with Superimposed Training in CP-OFDM Systems
Yang, Qinghai ; Kwak, Kyung-Sup ;
ETRI Journal, volume 28, issue 6, 2006, Pages 822~825
Based on superimposed training methods, a novel time-varying multipath channel estimation scheme is proposed for orthogonal frequency division multiplexing systems. We first develop a linear least square channel estimator, and meanwhile find the optimal superimposed sequences with respect to the channel estimates' mean square error. Next, a low-rank approximated channel estimator is obtained by using the singular value decomposition. As demonstrated in simulations, the proposed scheme achieves not only better performance but also higher bandwidth efficiency than the conventional pilot-aided approach.
Enhanced Optical Generation of 42.7 Gbps Phase Shaped Binary Transmission
Ducournau, Guillaume ; Latry, Olivier ; Ketata, Mohamed ;
ETRI Journal, volume 28, issue 6, 2006, Pages 826~829
A novel method for optical phase shaped binary transmission (PSBT) generation has been recently reported and experimentally evaluated. An amelioration of the optical signal-to-noise ratio (OSNR) sensitivity of the optical PSBT modulation format is proposed with the application of the concepts of enhanced electrical PSBT signal generation. Enhanced optical PSBT is proposed here as a modulation format producing a 0.7 dB gain in OSNR sensitivity compared to OPSBT, while maintaining a good robustness to group velocity dispersion: 100 ps/nm for enhanced optical PSBT and 120 ps/nm for optical PSBT, compared to 50 ps/nm for standard NRZ signals.