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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
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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Antenna Measurement on Cylindrical Surface in Fresnel Region Using Direct Far-Field Measurement System
Oh, Soon-Soo ; Kim, Joung-Myoun ; Yun, Jae-Hoon ;
ETRI Journal, volume 29, issue 2, 2007, Pages 135~142
The small anechoic chambers built by many small-/medium-sized companies and universities present difficulties in testing electrically large antennas because the chamber size cannot satisfy the far-field criterion of large antennas. In this paper, a method for Fresnel-region measurement on a cylindrical surface with variation of the measurement height is proposed and verified by both calculations and experiments. We implement the proposed method using a direct far-field measurement system by adding a few supporting structures. The results show good accuracy.
A Time-Varying Modified MMSE Detector for Multirate CDMA Signals in Fast Rayleigh Fading Channels
Jeong, Kil-Soo ; Yokoyama, Mitsuo ; Uehara, Hideyuki ;
ETRI Journal, volume 29, issue 2, 2007, Pages 143~152
In this paper, we propose a time-varying modified minimum mean-squared error (MMSE) detector for the detection of higher data rate signals in a multirate asynchronous code-division multiple-access (CDMA) system which is signaled in a fast Rayleigh fading channel. The interference viewed by a higher data rate symbol will be periodic due to the presence of a lower data rate symbol which spans multiple higher data rate symbols. The detection is carried out on the basis of a modified MMSE criterion which incorporates differential detection and the ratio of channel coefficients in two consecutive observation intervals inherently compensating the fast variation of the channel due to fading. The numerical results obtained by the MMSE detector with time-varying detection show around 3 dB (M=2) and 6 dB (M=4) performance improvement at a BER of
in the AWGN channel, while introducing more computational complexity than the MMSE detector without time-varying detection. At a higher
, the proposed scheme can achieve a BER of approximately
in the presence of fast channel variation which is an improvement over other schemes.
Calculation of Spectral Efficiency for Estimating Spectrum Requirements of IMT-Advanced in Korean Mobile Communication Environments
Chung, Woo-Ghee ; Lim, Eun-Taek ; Yook, Jong-Gwan ; Park, Han-Kyu ;
ETRI Journal, volume 29, issue 2, 2007, Pages 153~161
In this paper, we analyze the algorithm of the methodology developed by ITU for the calculation of spectrum requirements of IMT-Advanced. We propose an approach to estimate user density using traffic statistics, and to estimate spectrum efficiencies using carrier-to-interference ratio distribution and capacity theory as well as experimental data under Korean mobile communication environments. We calculate the IMT-Advanced spectrum requirements based on the user density and spectral efficiencies acquired from the new method. In the case of spectral efficiency using higher modulation and coding schemes, the spectrum requirement of IMT-Advanced is approximately 2700 MHz. When applying a
multiple-input multiple-output (MIMO) antenna system, it is approximately 1500 MHz; when applying a
MIMO antenna system, it is approximately 1050 MHz. Considering that the development of new technology will increase spectrum efficiency in the future, the spectrum requirement of IMT-Advanced in the Korean mobile communication environment is expected to be approximately 1 GHz bandwidth.
Bidirectional Hybrid DWDM-PON for HDTV/Gigabit Ethernet/CATV Applications
Lu, Hai-Han ; Tsai, Wen-Shing ; Chien, Tzu-Shen ; Chen, Shih-Hung ; Chi, Yu-Chieh ; Liao, Che-Wei ;
ETRI Journal, volume 29, issue 2, 2007, Pages 162~168
A new scheme for bi-directional HDTV/Gigabit Ethernet/CATV transmission over a hybrid dense-wavelength-division-multiplexing passive optical network (DWDM-PON) is proposed and demonstrated. It is based on injection-locked vertical-cavity surface-emitting lasers and distributed-feedback laser diodes as transmitters. Services with 129 HDTV channels, a 1.25 Gbps Gigabit Ethernet connection, and 77 CATV channels are successfully demonstrated over 40 km single-mode fiber links. Good performance of bit error rate, carrier-to-noise ratio, composite second order, and composite triple beat is achieved in our proposed bidirectional DWDM-PON.
Context-Aware Active Services in Ubiquitous Computing Environments
Moon, Ae-Kyung ; Kim, Hyoung-Sun ; Kim, Hyun ; Lee, Soo-Won ;
ETRI Journal, volume 29, issue 2, 2007, Pages 169~178
With the advent of ubiquitous computing environments, it has become increasingly important for applications to take full advantage of contextual information, such as the user's location, to offer greater services to the user without any explicit requests. In this paper, we propose context-aware active services based on context-aware middleware for URC systems (CAMUS). The CAMUS is a middleware that provides context-aware applications with a development and execution methodology. Accordingly, the applications based on CAMUS respond in a timely fashion to contextual information. This paper presents the system architecture of CAMUS and illustrates the content recommendation and control service agents with the properties, operations, and tasks for context-aware active services. To evaluate CAMUS, we apply the proposed active services to a TV application domain. We implement and experiment with a TV content recommendation service agent, a control service agent, and TV tasks based on CAMUS. The implemented content recommendation service agent divides the user's preferences into common and specific models to apply other recommendations and applications easily, including the TV content recommendations.
A Multi-Strategic Concept-Spotting Approach for Robust Understanding of Spoken Korean
Lee, Chang-Ki ; Eun, Ji-Hyun ; Jeong, Min-Woo ; Lee, Gary Geun-Bae ; Hwang, Yi-Gyu ; Jang, Myung-Gil ;
ETRI Journal, volume 29, issue 2, 2007, Pages 179~188
We propose a multi-strategic concept-spotting approach for robust spoken language understanding of conversational Korean in a hostile recognition environment such as in-car navigation and telebanking services. Our concept-spotting method adopts a partial semantic understanding strategy within a given specific domain since the method tries to directly extract predefined meaning representation slot values from spoken language inputs. In spite of partial understanding, we can efficiently acquire the necessary information to compose interesting applications because the meaning representation slots are properly designed for specific domain-oriented understanding tasks. We also propose a multi-strategic method based on this concept-spotting approach such as a voting method. We present experiments conducted to verify the feasibility of these methods using a variety of spoken Korean data.
Mobile Robot Exploration in Indoor Environment Using Topological Structure with Invisible Barcodes
Huh, Jin-Wook ; Chung, Woong-Sik ; Nam, Sang-Yep ; Chung, Wan-Kyun ;
ETRI Journal, volume 29, issue 2, 2007, Pages 189~200
This paper addresses the localization and navigation problem in the movement of service robots by using invisible two dimensional barcodes on the floor. Compared with other methods using natural or artificial landmarks, the proposed localization method has great advantages in cost and appearance since the location of the robot is perfectly known using the barcode information after mapping is finished. We also propose a navigation algorithm which uses a topological structure. For the topological information, we define nodes and edges which are suitable for indoor navigation, especially for large area having multiple rooms, many walls, and many static obstacles. The proposed algorithm also has the advantage that errors which occur in each node are mutually independent and can be compensated exactly after some navigation using barcodes. Simulation and experimental results were performed to verify the algorithm in the barcode environment, showing excellent performance results. After mapping, it is also possible to solve the kidnapped robot problem and to generate paths using topological information.
Opportunistic Scheduling with QoS Constraints for Multiclass Services HSUPA System
Liao, Dan ; Li, Lemin ;
ETRI Journal, volume 29, issue 2, 2007, Pages 201~211
This paper focuses on the scheduling problem with the objective of maximizing system throughput, while guaranteeing long-term quality of service (QoS) constraints for non-realtime data users and short-term QoS constraints for realtime multimedia users in multiclass service high-speed uplink packet access (HSUPA) systems. After studying the feasible rate region for multiclass service HSUPA systems, we formulate this scheduling problem and propose a multi-constraints HSUPA opportunistic scheduling (MHOS) algorithm to solve this problem. The MHOS algorithm selects the optimal subset of users for transmission at each time slot to maximize system throughput, while guaranteeing the different constraints. The selection is made according to channel condition, feasible rate region, and user weights, which are adjusted by stochastic approximation algorithms to guarantee the different QoS constraints at different time scales. Simulation results show that the proposed MHOS algorithm guarantees QoS constraints, and achieves high system throughput.
Low-Voltage CMOS Current Feedback Operational Amplifier and Its Application
Mahmoud, Soliman A. ; Madian, Ahmed H. ; Soliman, Ahmed M. ;
ETRI Journal, volume 29, issue 2, 2007, Pages 212~218
A novel low-voltage CMOS current feedback operational amplifier (CFOA) is presented. This realization nearly allows rail-to-rail input/output operations. Also, it provides high driving current capabilities. The CFOA operates at supply voltages of
with a total standby current of 304
. The circuit exhibits a bandwidth better than 120 MHz and a current drive capability of
mA. An application of the CFOA to realize a new all-pass filter is given. PSpice simulation results using 0.25
CMOS technology parameters for the proposed CFOA and its application are given.
The Effect of Incentives on the Performance of International IT Standardization Experts
Kang, Shin-Won ; Park, Hye-Jin ; Park, Ki-Shik ;
ETRI Journal, volume 29, issue 2, 2007, Pages 219~230
In this paper, we investigate the determinant factors of performance of global standardization experts in their standardization activities. Standards experts of various nationalities were surveyed to assess incentives that may positively influence the performance of standards professionals. As a basis for this study, we make three main assumptions. First, incentives can be important determinant factors of performance among standards experts. Second, standardization is in the public interest, insofar as the efficiency gains resulting from standardization benefit society as a whole. Third, based on this assumption that standardization is in the public interest, we propose that performance determinants for standardization activities tend to be non-monetary in nature rather than monetary. We find that, in order to improve performance among international standards experts, a better understanding of their aspirations and needs must be gained so that appropriate incentives may be proposed to them. Our analysis reveals that the two most important determinant factors of performance are the recognition of the professional status of international standards experts, and an environment providing support systems to help them perform to their fullest potential.
Simple Amplitude and Phase Predistortion for PAPR Reduction in OFDM Systems
Park, Jeong-Sang ; Lee, Jae-Kwon ; Kim, Jin-Up ;
ETRI Journal, volume 29, issue 2, 2007, Pages 231~233
One of the drawbacks in an OFDM system is the high peak-to-average power ratio (PAPR). Among a number of techniques to reduce the high PAPR, simple amplitude predistortion (SAP), a form of active constellation extension, has been proposed to effectively achieve the desired PAPR. In this letter, a novel scheme, simple amplitude and phase predistortion (SAPP), is proposed. In SAP the carriers' amplitude is utilized to combat the peak signal. Each amplitude is amplified according to its degree of contribution as a metric. In addition to amplitude, SAPP also utilizes the phase. Simulation results indicate that the proposed scheme provides better PAPR reduction than SAP.
Ultra-wideband Coexistence with WiBro
Yoon, Young-Keun ; Hong, Heon-Jin ; Choi, Ik-Guen ;
ETRI Journal, volume 29, issue 2, 2007, Pages 234~236
Interference effects of ultra-wideband devices using the frequency band from 3.1 to 10.6 GHz on wireless broadband are evaluated. The ultra-wideband emission power spectral density that would be necessary to protect a wireless broadband station is considered. Also, an analytic scheme based on a system level simulation of a WiBro system is proposed.
Application of SVD on Suppression of IEEE 802.11a Interference in TH-PAM UWB Systems
Xu, Shaoyi ; Bai, Zhiquan ; Yang, Qinghai ; Kwak, Kyung-Sup ;
ETRI Journal, volume 29, issue 2, 2007, Pages 237~239
Interference from IEEE 802.11a systems affects ultra-wideband (UWB) systems significantly. In this letter, we suggest a novel narrow-band interference (NBI) suppression technique based on the singular value decomposition (SVD) algorithm in time-hopping pulse amplitude modulation (TH-PAM) UWB systems. The SVD algorithm is used to approximate the interference which then is subtracted from the received signals. In contrast to the conventional notch filter and rake receiver, our method is more effective and the receiver complexity can be greatly reduced.
SMLD: Enhanced MIMO-Signal Detection for Wireless MIMO Communication Receivers
Baek, Myung-Sun ; Woo, Mi-Ae ; Lim, Jae-Hyuck ; You, Young-Hwan ; Song, Hyoung-Kyu ;
ETRI Journal, volume 29, issue 2, 2007, Pages 240~242
This letter proposes a simplified maximum likelihood detection (SMLD) scheme to improve the detection performance of multiple-input multiple-output receivers. The SMLD detects V streams according to the first detected V sub-streams. Through an ML test, the most probable stream is selected. Moreover, to detect the layer with the worst post-detection SNR accurately, reverse ordering is applied to the SMLD. Simulation results show that the performance of the Vertical Bell Laboratories layered space-time (V-BLAST) system can be improved by adopting the SMLD technique. In the case of reverse ordering, the SMLD can achieve a similar ML performance with significant reduction in computational complexity.
Facial Feature Extraction Based on Private Energy Map in DCT Domain
Kim, Ki-Hyun ; Chung, Yun-Su ; Yoo, Jang-Hee ; Ro, Yong-Man ;
ETRI Journal, volume 29, issue 2, 2007, Pages 243~245
This letter presents a new feature extraction method based on the private energy map (PEM) technique to utilize the energy characteristics of a facial image. Compared with a non-facial image, a facial image shows large energy congestion in special regions of discrete cosine transform (DCT) coefficients. The PEM is generated by energy probability of the DCT coefficients of facial images. In experiments, higher face recognition performance figures of 100% for the ORL database and 98.8% for the ETRI database have been achieved.
Image Retrieval via Query-by-Layout Using MPEG-7 Visual Descriptors
Kim, Sung-Min ; Park, Soo-Jun ; Won, Chee-Sun ;
ETRI Journal, volume 29, issue 2, 2007, Pages 246~248
Query-by-example (QBE) is a well-known method for image retrieval. In reality, however, an example image to be used for the query is rarely available. Therefore, it is often necessary to find a good example image to be used for the query before applying the QBE method. Query-by-layout (QBL) is our proposal for that purpose. In particular, we make use of the visual descriptors such as the edge histogram descriptor (EHD) and the color layout descriptor (CLD) in MPEG-7. Since image features of the CLD and the EHD can be localized in terms of a
sub-image, we can specify image features such as color and edge distribution on each sub-image separately for image retrieval without a query image. Experimental results show that the proposed query method can be used to retrieve a good image as a starting point for further QBE-based image retrieval.
Locating Intersections for Autonomous Vehicles: A Bayesian Network Approach
Choi, Kyoung-Ho ; Joo, Sung-Kwan ; Cho, Seong-Ik ; Park, Jong-Hyun ;
ETRI Journal, volume 29, issue 2, 2007, Pages 249~251
A novel idea is presented to locate intersections in a video sequence captured from a moving vehicle. More specifically, we propose a Bayesian network approach to combine evidence extracted from a video sequence and evidence from a database, maximizing evidence from various sensors in a systematic manner and locating intersections robustly.
A Strategic Grid for Implementing Ubiquitous Computing
Yeon, Seung-Jun ;
ETRI Journal, volume 29, issue 2, 2007, Pages 252~254
This letter offers a general framework representing the most effective strategies for implementing ubiquitous computing, given different levels of organizational information system capacity and business needs. The strategic grid offered here identifies promising movements which may potentially have a significant effect on the future development of ubiquitous computing.
Improved Selective Randomized Load Balancing in Mesh Networks
Zhang, Xiaoning ; Li, Lemin ; Wang, Sheng ; Yang, Fei ;
ETRI Journal, volume 29, issue 2, 2007, Pages 255~257
We propose an improved selective randomized load balancing (ISRLB) robust scheme under the hose uncertainty model for a special double-hop routing network architecture. The ISRLB architecture maintains the resilience properties of Valiant's load balancing and reduces the network cost/propagation delay in all other robust routing schemes.