• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.719-731
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• 2008

This paper defines QoE (Quality of Experience) for multi-view video streaming service over WiBro and proposes the CLO (Cross-Layer Optimization) algorithm can maximize this. Proposal CLO algorithm contains from physical layer to video layer. Under the time-varying wireless channel condition, the CLO technique takes view-wise and the temporal priority of the multi-view video into consideration in order to decide the transmission of frames and its FEC level. At the handover situation, it is shown through computer simulation that the optimal quality of the multi-view video can be achieved using the minimum amount of resources if the proposed CLO technique is applied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.414-422
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• 2011

This paper describes a design of low-density parity-check(LDPC) decoder supporting block length 2,304-bit and code rate 1/2 of IEEE 802.16e mobile WiMAX standard. The designed LDPC decoder employs the min-sum algorithm and partially parallel layered-decoding architecture which processes a sub-matrix of $96{\times}96$ in parallel. By exploiting the properties of the min-sum algorithm, a new memory reduction technique is proposed, which reduces check node memory by 46% compared to conventional method. Functional verification results show that it has average bit-error-rate(BER) of $4.34{\times}10^{-5}$ for AWGN channel with Fb/No=2.1dB. Our LDPC decoder synthesized with a $0.18{\mu}m$ CMOS cell library has 174,181 gates and 52,992 bits memory, and the estimated throughput is about 417 Mbps at 100-MHz@l.8-V.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.6
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• pp.531-539
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• 2013

Fingerprinting technique uses the radio signal strength measured reference locations is typically used, although there are many Wi-Fi based location tracking techniques. However, it needs numerous reference locations for precision and accuracy. This paper the analyzes problems of previous techniques and proposes a fingerprinting system using reliability based on a signal strength map. The system collects the signal strength data from a number of reference locations designated by the developer. And then it generates path-loss models to one of the access points for each reference location. These models calculate the predicted signal strength and reliability for a lattice. To evaluate proposed method and system performance, We perform experiments in a $20m{\times}22m$ real indoor environment installed access points. According to the result, the proposed system reduced distance error than RADAR. Comparing the existing system, it reduced about 1.74m.

• Investigative Magnetic Resonance Imaging
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• v.19 no.4
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• pp.224-230
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• 2015

Purpose: To determine whether we should recommend ultrasonography (US) for an incidental thyroid nodule identified by additional cervicothoracic sagittal T2-weighted image (C-T sag T2WI) of lumbar spine magnetic resonance imaging (MRI). Materials and Methods: A retrospective study of 61 patients who underwent both lumbar spine MRI and thyroid US between December 2011 and April 2015 was conducted. For all US-found thyroid nodules > 1 cm, investigators evaluated whether there was any correlation between thyroid nodule detectability by C-T sag T2WI and US features such as echogenicity, composition, or suspicion of malignancy. Results: Solid hypoechoic (2/4; 50%) or mixed echoic nodules (4/8; 50%) appeared to be found relatively more easily by C-T sag T2WI than more benign-looking solid isoechoic (1/4; 25%) or spongiform nodules (0/6; 0%). Among six nodules with ultrasonographic suspicion for malignancy, only one nodule was detected by C-T sag T2WI. Conclusion: If an incidental thyroid nodule is seen by C-T sag T2WI, it would be better to recommend thyroid US for identifying malignancy.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.17-23
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• 2021

In the present study, a more compact dual-band slot antenna is newly proposed for Wi-Fi application. The proposed antenna is composed of rectangular two stepped slot with open end which can generate standing wave resonance at dual frequency bands and L-type microstrip feed line. The measured impedance bandwidths are 50 MHz(2.412 ~ 2.470 GHz) at low frequency band and 452 MHz(5.451 ~ 5.903 GHz) at high frequency band respectiviely. Furthermore its size of 14 × 21 mm² is reduced by 30% compared to the size of 20 × 21 mm² of a conventional similar compact slot antenna. It has the omni-directional radiation pattern characteristics of a typical dipole antenna on the H-Plane, so it is suitable for commercial wireless network applications such as Wi-Fi.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1240-1247
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• 2019

In this paper, we designed a four-band antenna that can be applied to WLAN and WiMAX systems by designing a microstrip feeding structure, four branch lines and a slit on the ground plane. The proposed antenna is designed with a size of 16.0 mm (W1) × 48.0 mm (L8) on a dielectric substrate of 18.0 mm (W) × 50.0 mm (L) × 1.0 mm(h). and a slit of 2.9 mm (W7) × 4.0 mm (L7) is inserted into the ground plane of 18.0 mm (W) × 18.7 mm (L6). Based on -10 dB production and measurement results, it obtained 60.8 MHz (8,730~9,338 MHz), 310 MHz (2.33~2.64 GHz) in the 2.4 GHz band, 420MHz (3.39~3.81 GHz) in the 3.4 GHz band, and 2,070 MHz (4.62~6.69 GHz) in the 5.0 GHz. In addition, the gain and radiation pattern characteristics of the quadrant band are measured from the measurement results anechoic chamber.

• ETRI Journal
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• v.37 no.1
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• pp.21-25
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• 2015

A miniaturized triple-band antenna suitable for wireless USB dongle applications is proposed and investigated in this paper. The presented antenna, simply consisting of a circular-arc-shaped stub, an L-shaped stub, a microstrip feed line, and a rectangular ground plane has a compact size of $16mm{\times}38.5mm$ and is capable of generating three separate resonant modes with very good impedance matching. The measurement results show that the antenna has several impedance bandwidths for S11 ${\leq}$ -10 dB of 260 MHz (2.24 GHz to 2.5 GHz), 320 MHz (3.4 GHz to 3.72 GHz), and 990 MHz (5.1 GHz to 6.09 GHz), which can be applied to both 2.4/5.2/5.8 GHz WLAN bands and 3.5/5.5 GHz WiMAX bands. Moreover, nearly-omni-directional radiation patterns and stable gain across the operating bands can be obtained.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.1027-1032
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• 2012

Importance of security is emphasized along with development of local area network such as NFC, Bluetooth, WiFi etc., but research that is worth watching eagerly up to now is not gone. This paper proposed SSEN algorithm for security elevation of approximation communication network. Proposed SSEN algorithm is algorithm that special cryptographic function creates own key without necessity. Also, SSEN achieving certification function additionally, did so that can have more than performance about the processing speed and mistake of service voluntarily.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.394-403
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• 2008

The effects of water injection (WI) and urea injection for NOx on a 4-cylinder Direct Injection (DI) diesel engine were investigated experimentally. For water injection, it was installed at the intake pipe and the water quantity was controlled at the intake manifold and Manifold Air Flow (MAF) temperatures while the urea injection was located at the exhaust pipe and the urea quantity was controlled by NOx quantity and MAF. The effects of WI system, urea-SCR system and the combined system were investigated with and without exhaust gas recirculation (EGR). Several experiments were performed to characterize the urea-SCR system, using engine operating points of varying raw NOx emissions. The results of the Stoichiometric Urea Flow (SUF) and NOx map were obtained. In addition, NOx results were illustrated according to the engine speed and load. It is concluded that the NOx reduction effects of the combined system without the EGR were better than those with the EGR-based engine.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.8
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• pp.1-10
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• 1993

In this paper, we will propose 4-move ZKIP and its application. Using bit-commitment scheme that is necessary to organize the ZKIP related to NP-Complete problem and WH and WI preserving the property for security under parallel composition of protocols, we will show that the proposed ZKIP is 4-move ZKIP of SAT comparing to 6-move ZKIP of SAT proposed by Brassard. Chaum and Yung, and under claw-free pairs of function the proposed ZKIP is also 4-move ZKIP comparing to 5-move ZKIP proposed by Goldreich and Krawczyk under the same assumption. Moreover we will show the efficiency of the proposed scheme better than Fiat and Shamir's scheme at the points of computational complexity and communication complexity, and also propose the efficient and secure identification scheme against the chosen ciphertext attack, using the proposed scheme.