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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 36, Issue 6 - Dec 2014
Volume 36, Issue 5 - Oct 2014
Volume 36, Issue 4 - Aug 2014
Volume 36, Issue 3 - Jun 2014
Volume 36, Issue 2 - Apr 2014
Volume 36, Issue 1 - Feb 2014
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Data Clustering Method Using a Modified Gaussian Kernel Metric and Kernel PCA
Lee, Hansung ; Yoo, Jang-Hee ; Park, Daihee ;
ETRI Journal, volume 36, issue 3, 2014, Pages 333~342
DOI : 10.4218/etrij.14.0113.0553
Most hyper-ellipsoidal clustering (HEC) approaches use the Mahalanobis distance as a distance metric. It has been proven that HEC, under this condition, cannot be realized since the cost function of partitional clustering is a constant. We demonstrate that HEC with a modified Gaussian kernel metric can be interpreted as a problem of finding condensed ellipsoidal clusters (with respect to the volumes and densities of the clusters) and propose a practical HEC algorithm that is able to efficiently handle clusters that are ellipsoidal in shape and that are of different size and density. We then try to refine the HEC algorithm by utilizing ellipsoids defined on the kernel feature space to deal with more complex-shaped clusters. The proposed methods lead to a significant improvement in the clustering results over K-means algorithm, fuzzy C-means algorithm, GMM-EM algorithm, and HEC algorithm based on minimum-volume ellipsoids using Mahalanobis distance.
Characterization of Fluxing and Hybrid Underfills with Micro-encapsulated Catalyst for Long Pot Life
Eom, Yong-Sung ; Son, Ji-Hye ; Jang, Keon-Soo ; Lee, Hak-Sun ; Bae, Hyun-Cheol ; Choi, Kwang-Seong ; Choi, Heung-Soap ;
ETRI Journal, volume 36, issue 3, 2014, Pages 343~351
DOI : 10.4218/etrij.14.0113.0570
For the fine-pitch application of flip-chip bonding with semiconductor packaging, fluxing and hybrid underfills were developed. A micro-encapsulated catalyst was adopted to control the chemical reaction at room and processing temperatures. From the experiments with a differential scanning calorimetry and viscometer, the chemical reaction and viscosity changes were quantitatively characterized, and the optimum type and amount of micro-encapsulated catalyst were determined to obtain the best pot life from a commercial viewpoint. It is expected that fluxing and hybrid underfills will be applied to fine-pitch flip-chip bonding processes and be highly reliable.
A 900 MHz Zero-IF RF Transceiver for IEEE 802.15.4g SUN OFDM Systems
Kim, Changwan ; Lee, Seungsik ; Choi, Sangsung ;
ETRI Journal, volume 36, issue 3, 2014, Pages 352~360
DOI : 10.4218/etrij.14.0113.0549
This paper presents a 900 MHz zero-IF RF transceiver for IEEE 802.15.4g Smart Utility Networks OFDM systems. The proposed RF transceiver comprises an RF front end, a Tx baseband analog circuit, an Rx baseband analog circuit, and a
fractional-N frequency synthesizer. In the RF front end, re-use of a matching network reduces the chip size of the RF transceiver. Since a T/Rx switch is implemented only at the input of the low noise amplifier, the driver amplifier can deliver its output power to an antenna without any signal loss; thus, leading to a low dc power consumption. The proposed current-driven passive mixer in Rx and voltage-mode passive mixer in Tx can mitigate the IQ crosstalk problem, while maintaining 50% duty-cycle in local oscillator clocks. The overall Rx-baseband circuits can provide a voltage gain of 70 dB with a 1 dB gain control step. The proposed RF transceiver is implemented in a
CMOS technology and consumes 37 mA in Tx mode and 38 mA in Rx mode from a 1.8 V supply voltage. The fabricated chip shows a Tx average power of -2 dBm, a sensitivity level of -103 dBm at 100 Kbps with PER < 1%, an Rx input
of -11 dBm, and an Rx input IP3 of -2.3 dBm.
Study of Capacitive Tilt Sensor with Metallic Ball
Lee, Chang Hwa ; Lee, Seung Seob ;
ETRI Journal, volume 36, issue 3, 2014, Pages 361~366
DOI : 10.4218/etrij.14.0113.0671
In this paper, a new, simple capacitive tilt sensor with a metallic ball is proposed. The proposed tilt sensor has only two electrodes and a metallic ball, and this design assists in managing the inherent contact problem in measuring tilt angles. Capacitive sensing, compared with other types of tilt sensor, has many advantages such as simplicity, noncontact measurement, long-throw linear displacement, and sub-micron plate spacing. Its design and fabrication process are significantly simpler than previous types of tilt sensors. The dimensions of the prototype tilt sensor are
, and the diameter of the polystyrene tube is 5 mm with a tube thickness of 0.15 mm. An analytical study of the prototype capacitive tilt sensor was undertaken, and the experimental results demonstrate the relationship between the tilt angles and measured capacitances compared with the analytical study.
New Path-Setup Method for Optical Network-on-Chip
Gu, Huaxi ; Gao, Kai ; Wang, Zhengyu ; Yang, Yintang ; Yu, Xiaoshan ;
ETRI Journal, volume 36, issue 3, 2014, Pages 367~373
DOI : 10.4218/etrij.14.0113.0675
With high bandwidth, low interference, and low power consumption, optical network-on-chip (ONoC) has emerged as a highly efficient interconnection for the future generation of multicore system on chips. In this paper, we propose a new path-setup method for ONoC to mitigate contentions, such as packets, by recycling the setup packet halfway to the destination. A new, strictly non-blocking
optical router is designed to support the new method. The simulation results show the new path-setup method increases the throughput by 52.03%, 41.94%, and 36.47% under uniform, hotspot-I, and hotspot-II traffic patterns, respectively. The end-to-end delay performance is also improved.
Time-Slotted Scheduling Schemes for Multi-hop Concurrent Transmission in WPANs with Directional Antenna
Bilal, Muhammad ; Kang, Moonsoo ; Shah, Sayed Chhattan ; Kang, Shin-Gak ;
ETRI Journal, volume 36, issue 3, 2014, Pages 374~384
DOI : 10.4218/etrij.14.0113.0703
To achieve high-speed (giga-bit) connectivity for short-range wireless multimedia applications, the millimeter-wave (mmWave) wireless personal area networks with directional antennas are gaining increased interest. Due to the use of directional antennas and mmWave communications, the probability of non-interfering transmissions increases in a localized region. Network throughput can be increased immensely by the concurrent time allocation of non-interfering transmissions. The problem of finding optimum time allocation for concurrent transmissions is an NP-hard problem. In this paper, we propose two enhanced versions of previously proposed multi-hop concurrent transmission (MHCT) schemes. To increase network capacity, the proposed schemes efficiently make use of the free holes in the time-allocation map of the MHCT scheme; thus, making it more compact.
Resource Allocation Scheme for Millimeter Wave-Based WPANs Using Directional Antennas
Kim, Meejoung ; Kim, Yongsun ; Lee, Wooyong ;
ETRI Journal, volume 36, issue 3, 2014, Pages 385~395
DOI : 10.4218/etrij.14.0113.0691
In this paper, we consider a resource allocation scheme for millimeter wave-based wireless personal area networks using directional antennas. This scheme involves scheduling the reservation period of medium access control for IEEE 802.15.3c. Objective functions are considered to minimize the average delay and maximize throughput; and two scheduling algorithms-namely, MInMax concurrent transmission and MAxMin concurrent transmission-are proposed to provide a suboptimal solution to each objective function. These are based on an exclusive region and two decision rules that determine the length of reservation times and the transmission order of groups. Each group consists of flows that are concurrently transmittable via spatial reuse. The algorithms appropriately apply two decision rules according to their objectives. A real video trace is used for the numerical results, which show that the proposed algorithms satisfy their objectives. They outperform other schemes on a range of measures, showing the effect of using a directional antenna. The proposed scheme efficiently supports variable bit rate traffic during the reservation period, reducing resource waste.
OFEX Controller to Improve Queueing and User Performance in Multi-bottleneck Networks
Liu, Jungang ; Yang, Oliver W.W. ;
ETRI Journal, volume 36, issue 3, 2014, Pages 396~406
DOI : 10.4218/etrij.14.0113.0036
We have designed and investigated a new congestion control scheme, called optimal and fully explicit (OFEX) controller. Different from existing relatively explicit controllers, this new scheme can provide not only optimal bandwidth allocation but also a fully explicit congestion signal to sources. It uses the congestion signal from the most congested link instead of the cumulative signal from the flow path. In this way, it overcomes the drawback of relatively explicit controllers exhibiting bias toward multi-bottlenecked users and significantly improves their convergence speed and source throughput performance. Furthermore, our OFEX-controller design considers a dynamic model by proposing a remedial measure against the unpredictable bandwidth changes in contention-based multi-access networks. Compared with former works/controllers, this remedy also effectively reduces the instantaneous queue size in a router and thus significantly improves queuing delay and packet loss performance. We have evaluated the effectiveness of the OFEX controller in OPNET. The experimental comparison with the existing relatively explicit controllers verifies the superiority of our new scheme.
Early Coding Unit-Splitting Termination Algorithm for High Efficiency Video Coding (HEVC)
Goswami, Kalyan ; Kim, Byung-Gyu ; Jun, Dongsan ; Jung, Soon-Heung ; Choi, Jin Soo ;
ETRI Journal, volume 36, issue 3, 2014, Pages 407~417
DOI : 10.4218/etrij.14.0113.0458
A new-generation video coding standard, named High Efficiency Video Coding (HEVC), has recently been developed by JCT-VC. This new standard provides a significant improvement in picture quality, especially for high-resolution videos. However, one the most important challenges in HEVC is time complexity. A quadtree-based structure is created for the encoding and decoding processes and the rate-distortion (RD) cost is calculated for all possible dimensions of coding units in the quadtree. This provides a high encoding quality, but also causes computational complexity. We focus on a reduction scheme of the computational complexity and propose a new approach that can terminate the quadtree-based structure early, based on the RD costs of the parent and current levels. Our proposed algorithm is compared with HEVC Test Model version 10.0 software and a previously proposed algorithm. Experimental results show that our algorithm provides a significant time reduction for encoding, with only a small loss in video quality.
Predicting the Lifespan and Retweet Times of Tweets Based on Multiple Feature Analysis
Bae, Yongjin ; Ryu, Pum-Mo ; Kim, Hyunki ;
ETRI Journal, volume 36, issue 3, 2014, Pages 418~428
DOI : 10.4218/etrij.14.0113.0657
In social network services, such as Facebook, Google+, Twitter, and certain postings attract more people than others. In this paper, we propose a novel method for predicting the lifespan and retweet times of tweets, the latter being a proxy for measuring the popularity of a tweet. We extract information from retweet graphs, such as posting times; and social, local, and content features, so as to construct prediction knowledge bases. Tweets with a similar topic, retweet pattern, and properties are sequentially extracted from the knowledge base and then used to make a prediction. To evaluate the performance of our model, we collected tweets on Twitter from June 2012 to October 2012. We compared our model with conventional models according to the prediction goal. For the lifespan prediction of a tweet, our model can reduce the time tolerance of a tweet lifespan by about four hours, compared with conventional models. In terms of prediction of the retweet times, our model achieved a significantly outstanding precision of about 50%, which is much higher than two of the conventional models showing a precision of around 30% and 20%, respectively.
Domain-Adaptation Technique for Semantic Role Labeling with Structural Learning
Lim, Soojong ; Lee, Changki ; Ryu, Pum-Mo ; Kim, Hyunki ; Park, Sang Kyu ; Ra, Dongyul ;
ETRI Journal, volume 36, issue 3, 2014, Pages 429~438
DOI : 10.4218/etrij.14.0113.0645
Semantic role labeling (SRL) is a task in natural-language processing with the aim of detecting predicates in the text, choosing their correct senses, identifying their associated arguments, and predicting the semantic roles of the arguments. Developing a high-performance SRL system for a domain requires manually annotated training data of large size in the same domain. However, such SRL training data of sufficient size is available only for a few domains. Constructing SRL training data for a new domain is very expensive. Therefore, domain adaptation in SRL can be regarded as an important problem. In this paper, we show that domain adaptation for SRL systems can achieve state-of-the-art performance when based on structural learning and exploiting a prior model approach. We provide experimental results with three different target domains showing that our method is effective even if training data of small size is available for the target domains. According to experimentations, our proposed method outperforms those of other research works by about 2% to 5% in F-score.
State Machine and Downhill Simplex Approach for Vision-Based Nighttime Vehicle Detection
Choi, Kyoung-Ho ; Kim, Do-Hyun ; Kim, Kwang-Sup ; Kwon, Jang-Woo ; Lee, Sang-Il ; Chen, Ken ; Park, Jong-Hyun ;
ETRI Journal, volume 36, issue 3, 2014, Pages 439~449
DOI : 10.4218/etrij.14.0113.0509
In this paper, a novel vision-based nighttime vehicle detection approach is presented, combining state machines and downhill simplex optimization. In the proposed approach, vehicle detection is modeled as a sequential state transition problem; that is, vehicle arrival, moving, and departure at a chosen detection area. More specifically, the number of bright pixels and their differences, in a chosen area of interest, are calculated and fed into the proposed state machine to detect vehicles. After a vehicle is detected, the location of the headlights is determined using the downhill simplex method. In the proposed optimization process, various headlights were evaluated for possible headlight positions on the detected vehicles; allowing for an optimal headlight position to be located. Simulation results were provided to show the robustness of the proposed approach for nighttime vehicle and headlight detection.
Single Image-Based 3D Tree and Growth Models Reconstruction
Kim, Jaehwan ; Jeong, Il-Kwon ;
ETRI Journal, volume 36, issue 3, 2014, Pages 450~459
DOI : 10.4218/etrij.14.0113.0069
In this paper, we present a new, easy-to-generate system that is capable of creating virtual 3D tree models and simulating a variety of growth processes of a tree from a single, real tree image. We not only construct various tree models with the same trunk through our proposed digital image matting method and skeleton-based abstraction of branches, but we also animate the visual growth of the constructed 3D tree model through usage of the branch age information combined with a scaling factor. To control the simulation of a tree growth process, we consider tree-growing attributes, such as branching orders, branch width, tree size, and branch self-bending effect, at the same time. Other invisible branches and leaves are automatically attached to the tree by employing parametric branch libraries under the conventional procedural assumption of structure having a local self-similarity. Simulations with a real image confirm that our system makes it possible to achieve realistic tree models and growth processes with ease.
Joint Estimation of TOA and DOA in IR-UWB System Using Sparse Representation Framework
Wang, Fangqiu ; Zhang, Xiaofei ;
ETRI Journal, volume 36, issue 3, 2014, Pages 460~468
DOI : 10.4218/etrij.14.0113.0555
This paper addresses the problem of joint time of arrival (TOA) and direction of arrival (DOA) estimation in impulse radio ultra-wideband systems with a two-antenna receiver and links the joint estimation of TOA and DOA to the sparse representation framework. Exploiting this link, an orthogonal matching pursuit algorithm is used for TOA estimation in the two antennas, and then the DOA parameters are estimated via the difference in the TOAs between the two antennas. The proposed algorithm can work well with a single measurement vector and can pair TOA and DOA parameters. Furthermore, it has better parameter-estimation performance than traditional propagator methods, such as, estimation of signal parameters via rotational invariance techniques algorithms matrix pencil algorithms, and other new joint-estimation schemes, with one single snapshot. The simulation results verify the usefulness of the proposed algorithm.
Improved Shamir's CRT-RSA Algorithm: Revisit with the Modulus Chaining Method
Lee, Seungkwang ; Choi, Dooho ; Choi, Yongje ;
ETRI Journal, volume 36, issue 3, 2014, Pages 469~478
DOI : 10.4218/etrij.14.0113.0317
RSA signature algorithms using the Chinese remainder theorem (CRT-RSA) are approximately four-times faster than straightforward implementations of an RSA cryptosystem. However, the CRT-RSA is known to be vulnerable to fault attacks; even one execution of the algorithm is sufficient to reveal the secret keys. Over the past few years, several countermeasures against CRT-RSA fault attacks have tended to involve additional exponentiations or inversions, and in most cases, they are also vulnerable to new variants of fault attacks. In this paper, we review how Shamir's countermeasure can be broken by fault attacks and improve the countermeasure to prevent future fault attacks, with the added benefit of low additional costs. In our experiment, we use the side-channel analysis resistance framework system, a fault injection testing and verification system, which enables us to inject a fault into the right position, even to within
. We also explain how to find the exact timing of the target operation using an Atmega128 software board.
A Model-Based Image Steganography Method Using Watson's Visual Model
Fakhredanesh, Mohammad ; Safabakhsh, Reza ; Rahmati, Mohammad ;
ETRI Journal, volume 36, issue 3, 2014, Pages 479~489
DOI : 10.4218/etrij.14.0113.0171
This paper presents a model-based image steganography method based on Watson's visual model. Model-based steganography assumes a model for cover image statistics. This approach, however, has some weaknesses, including perceptual detectability. We propose to use Watson's visual model to improve perceptual undetectability of model-based steganography. The proposed method prevents visually perceptible changes during embedding. First, the maximum acceptable change in each discrete cosine transform coefficient is extracted based on Watson's visual model. Then, a model is fitted to a low-precision histogram of such coefficients and the message bits are encoded to this model. Finally, the encoded message bits are embedded in those coefficients whose maximum possible changes are visually imperceptible. Experimental results show that changes resulting from the proposed method are perceptually undetectable, whereas model-based steganography retains perceptually detectable changes. This perceptual undetectability is achieved while the perceptual quality - based on the structural similarity measure - and the security - based on two steganalysis methods - do not show any significant changes.
Relationship between Service-Related Activities, Service Capability and Market Diffusion: Case of WiBro
Kim, Moon-Koo ; Park, Jong-Hyun ; Paik, Jong-Hyun ;
ETRI Journal, volume 36, issue 3, 2014, Pages 490~497
DOI : 10.4218/etrij.14.0113.0396
The market performance of WiBro in Korea has not been as expected, and its rapid diffusion in the near future is unlikely owing to the existence of competing services. There has been little research on the factors affecting this low market diffusion. This study is based on an analytical framework in which a lack of service capability and the insufficiency of service-related activities have resulted in the current poor market performance. An expert survey was conducted on WiBro specialists and verified using the analytical hierarchy process method. The result of this analysis is as follows: underinvestment in network deployment and marketing, insufficient promotional policies, and a shortage of service capabilities are to be analyzed as the main causes of WiBro's low market diffusion.
A Compact C-Band 50 W AlGaN/GaN High-Power MMIC Amplifier for Radar Applications
Jeong, Jin-Cheol ; Jang, Dong-Pil ; Han, Byoung-Gon ; Yom, In-Bok ;
ETRI Journal, volume 36, issue 3, 2014, Pages 498~501
DOI : 10.4218/etrij.14.0213.0415
A C-band 50 W high-power microwave monolithic integrated circuit amplifier for use in a phased-array radar system was designed and fabricated using commercial
AlGaN/GaN technology. This two-stage amplifier can achieve a saturated output power of 50 W with higher than 35% power-added efficiency and 22 dB small-signal gain over a frequency range of 5.5 GHz to 6.2 GHz. With a compact
chip area, an output power density of
Cluster-Based Polarized Spectrum Sharing in Channels with Polarization Mode Dispersion
Li, Dongming ; Zeng, Zhimin ; Guo, Caili ; Lin, Xiaolin ;
ETRI Journal, volume 36, issue 3, 2014, Pages 502~505
DOI : 10.4218/etrij.14.0213.0458
Polarized spectrum sharing (PSS) exploits the spectrum opportunities in a polarized domain. However, when it comes to wideband environments PSS is impaired by the frequency-dependent polarization mode dispersion (PMD); thus, the effective throughput of PSS drops. To combat the PMD effect, this work proposes a cluster-based PSS approach to enable PSS on a narrower frequency span. Simulation results show that the effective throughput of PSS on cluster basis outperforms that of PSS on bandwidth and subcarrier basis.
Robust Energy Efficiency Power Allocation for Uplink OFDM-Based Cognitive Radio Networks
Zuo, Jiakuo ; Dao, Van Phuong ; Bao, Yongqiang ; Fang, Shiliang ; Zhao, Li ; Zou, Cairong ;
ETRI Journal, volume 36, issue 3, 2014, Pages 506~509
DOI : 10.4218/etrij.14.0213.0262
This paper studies the energy efficiency power allocation for cognitive radio networks based on uplink orthogonal frequency-division multiplexing. The power allocation problem is intended to minimize the maximum energy efficiency measured by "Joule per bit" metric, under total power constraint and robust aggregate mutual interference power constraint. However, the above problem is non-convex. To make it solvable, an equivalent convex optimization problem is derived that can be solved by general fractional programming. Then, a robust energy efficiency power allocation scheme is presented. Simulation results corroborate the effectiveness of the proposed methods.
High Performance Millimeter-Wave Image Reject Low-Noise Amplifier Using Inter-stage Tunable Resonators
Kim, Jihoon ; Kwon, Youngwoo ;
ETRI Journal, volume 36, issue 3, 2014, Pages 510~513
DOI : 10.4218/etrij.14.0213.0325
A Q-band pHEMT image-rejection low-noise amplifier (IR-LNA) is presented using inter-stage tunable resonators. The inter-stage L-C resonators can maximize an image rejection by functioning as inter-stage matching circuits at an operating frequency (
) and short circuits at an image frequency (
). In addition, it also brings more wideband image rejection than conventional notch filters. Moreover, tunable varactors in L-C resonators not only compensate for the mismatch of an image frequency induced by the process variation or model error but can also change the image frequency according to a required RF frequency. The implemented pHEMT IR-LNA shows 54.3 dB maximum image rejection ratio (IRR). By changing the varactor bias, the image frequency shifts from 27 GHz to 37 GHz with over 40 dB IRR, a 19.1 dB to 17.6 dB peak gain, and 3.2 dB to 4.3 dB noise figure. To the best of the authors' knowledge, it shows the highest IRR and
of the reported millimeter/quasi-millimeter wave IR-LNAs.
Intra-and Inter-frame Features for Automatic Speech Recognition
Lee, Sung Joo ; Kang, Byung Ok ; Chung, Hoon ; Lee, Yunkeun ;
ETRI Journal, volume 36, issue 3, 2014, Pages 514~517
DOI : 10.4218/etrij.14.0213.0181
In this paper, alternative dynamic features for speech recognition are proposed. The goal of this work is to improve speech recognition accuracy by deriving the representation of distinctive dynamic characteristics from a speech spectrum. This work was inspired by two temporal dynamics of a speech signal. One is the highly non-stationary nature of speech, and the other is the inter-frame change of a speech spectrum. We adopt the use of a sub-frame spectrum analyzer to capture very rapid spectral changes within a speech analysis frame. In addition, we attempt to measure spectral fluctuations of a more complex manner as opposed to traditional dynamic features such as delta or double-delta. To evaluate the proposed features, speech recognition tests over smartphone environments were conducted. The experimental results show that the feature streams simply combined with the proposed features are effective for an improvement in the recognition accuracy of a hidden Markov model-based speech recognizer.