• Title/Summary/Keyword: AOA

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Design of VDL Mode 2 Protocol under AOA Network for the Implementation of Bit-oriented ATS Applications (AOA망 환경에서 ATS 애플리케이션 구현을 위한 VDL Mode 2 데이터링크 프로토콜 설계)

  • Bae, Joong-won;Kim, Hyoun-kyoung;Kim, In-kyu;Kim, Tae-sik;Kim, Dong-min
    • Journal of Aerospace System Engineering
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    • v.1 no.4
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    • pp.13-21
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    • 2007
  • As one of YHF digital data link technologies, VDL Mode 2 is designed to be an air-to-ground subnetwork of the Aeronautical Telecommunication Network (ATN) based on the Open System Interconnection (OSI) architecture. VDL Mode 2 can be used in ATS Applications especially for CPDLC and ADS. And it is also expected to replace ACARS (Aircraft Communications Addressing and Reporting System) which has broadly been used in AOC for over 20 years. This paper presents the design result of VDL Mode 2 system under AOA (ACARS Over AVLC) environment for the implementation of bit-oriented ATS applications. The system is composed of airborne and ground subsystem. Airborne subsystem consists of VDR, CMU and an aircraft test equipment with CPDLC/ADS client applications for operational test and ground system consists of Ground Station which includes ground VDR and ground communication controller, simple DSP (Datalink Service Processor) and a ground test equipment with CPDLC/ADS server applications.

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The Design of Abstract Layer for Motion Capture System (모션캡처 시스템을 위한 추상레이어의 설계)

  • Lee, Hee-Man
    • Journal of the Korea Society of Computer and Information
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    • v.12 no.1 s.45
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    • pp.25-32
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    • 2007
  • In this paper, the abstract layer for motion capture system is designed and implemented to meet the various hardware and different capturing method. The abstract layer can offer the unified programming by providing device independent API(Application Programming Interface). The device drivers of the optical system and mechanical system are emulated to verify the designed abstract layer. The optical system employs the AOA Ole while the mechanical system uses BVH file. An application program is written to call the abstract layer functions to drive both optical and mechanical drivers and receive the frame data, simulated motion data, that are displayed sequentially on the computer screen by utilizing Direct3D.

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Design and development of VDL Mode 2 System (VDL 모드 2 데이터링크 시스템 설계 및 구현)

  • Bae, Joong-Won;Kim, Hyoung-Kyoung;Kim, In-Kyu;Kim, Tae-Sik
    • Aerospace Engineering and Technology
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    • v.7 no.1
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    • pp.30-39
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    • 2008
  • This paper presents the result of VDL Mode 2 system design and implementation with AOA (ACARS Over AVLC) protocol based on international VDL Mode 2 specifications for the bit-oriented ATS applications. The designed VDL Mode 2 system is composed of airborne and ground subsystem. Airborne subsystem consists of VDR, CMU and Ground system consists of Ground Station and DSP. For the test of whole system, simplified CPDLC, ADS and AFN applications are implemented in test equipments.

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The consideration about pressure on surface of cone shape in experiments of supersonic wind tunnel I (초음속풍동실험에서 원뿔형상의 표면에서 측정되는 압력에 대한 고찰 I)

  • Lee, Jae-Ho;Choi, Jong-Ho;Yoon, Hyun-Gull;Kim, Kyu-Hong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.04a
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    • pp.391-394
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    • 2011
  • In this paper, the shock angle and effect had been compared with numerical data within supersonic area at an forebody such as missiles or an aircraft. By using supersonic wind tunnel in Seoul National University, The shock position and magnitude were measured in the model of cone shape according to mach number. The experiment had been conducted at mach number 2.0, 3.0, and 3.8. As a result, the shock position and magnitude are different from flow velocity, AOA, and AOS in some cases blockage effect had occurred.

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Pilot Sequence Assignment for Spatially Correlated Massive MIMO Circumstances

  • Li, Pengxiang;Gao, Yuehong;Li, Zhidu;Yang, Dacheng
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.1
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    • pp.237-253
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    • 2019
  • For massive multiple-input multiple-output (MIMO) circumstances with time division duplex (TDD) protocol, pilot contamination becomes one of main system performance bottlenecks. This paper proposes an uplink pilot sequence assignment to alleviate this problem for spatially correlated massive MIMO circumstances. Firstly, a single-cell TDD massive MIMO model with multiple terminals in the cell is established. Then a spatial correlation between two channel response vectors is established by the large-scale fading variables and the angle of arrival (AOA) span with an infinite number of base station (BS) antennas. With this spatially correlated channel model, the expression for the achievable system capacity is derived. To optimize the achievable system capacity, a problem regarding uplink pilot assignment is proposed. In view of the exponential complexity of the exhaustive search approach, a pilot assignment algorithm corresponding to the distinct channel AOA intervals is proposed to approach the optimization solution. In addition, simulation results prove that the main pilot assignment algorithm in this paper can obtain a noticeable performance gain with limited BS antennas.

Utilizing Block chain in the Internet of Things for an Effective Security Sharing Scheme

  • Sathish C;Yesubai Rubavathi, C
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.17 no.6
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    • pp.1600-1619
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    • 2023
  • Organizations and other institutions have recently started using cloud service providers to store and share information in light of the Internet of Things (IoT). The major issues with this storage are preventing unauthorized access and data theft from outside parties. The Block chain based Security Sharing scheme with Data Access Control (BSSDAC) was implemented to improve access control and secure data transaction operations. The goal of this research is to strengthen Data Access Control (DAC) and security in IoT applications. To improve the security of personal data, cypher text-Policy Attribute-Based Encryption (CP-ABE) can be developed. The Aquila Optimization Algorithm (AOA) generates keys in the CP-ABE. DAC based on a block chain can be created to maintain the owner's security. The block chain based CP-ABE was developed to maintain secures data storage to sharing. With block chain technology, the data owner is enhancing data security and access management. Finally, a block chain-based solution can be used to secure data and restrict who has access to it. Performance of the suggested method is evaluated after it has been implemented in MATLAB. To compare the proposed method with current practices, Rivest-Shamir-Adleman (RSA) and Elliptic Curve Cryptography (ECC) are both used.

Effects of age of L2 acquisition and L2 experience on the production of English vowels by Korean speakers

  • Eunhae Oh;Eunyoung Shin
    • Phonetics and Speech Sciences
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    • v.15 no.3
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    • pp.9-16
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    • 2023
  • The current study investigated the influence of age of L2 acquisition (AOA) and length of residence (LOR) in the L2 setting country on the production of voicing-conditioned vowel duration and spectral qualities in English by Korean learners. The primary aim was to explore the ways in which the language-specific phonetic features are acquired by the age of onset and L2 experience. Analyses of the archived corpus data produced by 45 native speakers of Korean showed that, regardless of AOA or LOR, absolute vowel duration was used as a salient correlate of voicing contrast in English for Korean learners. The accuracy of relative vowel duration was influenced more by onset age than by L2 experience, suggesting that being exposed to English at an early age may benefit the acquisition of temporal dimension. On the other hand, the spectral characteristics of English vowels were more consistently influenced by L2 experience, indicating that immersive experience in the L2 speaking environment are likely to improve the accurate production of vowel quality. The distinct influence of the onset age and L2 experience on the specific phonetic cues in L2 vowel production provides insight into the intricate relationship between the two factors on the manifestation of L2 phonological knowledge.

The Cost-effective Architecture Design of an Angle-of-Arrival Estimator in UWB Systems (UWB 시스템에서 입사각 추정기의 효율적인 하드웨어 구조 설계)

  • Lee, Seong-Joo;Han, Kwi-Beum
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.44 no.11
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    • pp.137-141
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    • 2007
  • This paper proposes a cost-effective architecture design of an angle-of-arrival (AOA) estimator based on the multiple signal identification and classification (MUSIC) algerian in UWB systems adapting Multi-band OFDM (MB-OFDM) techniques with two-receive antennas. In the proposed method, by modifying the equations of algorithm in order to remove the high computational functions, the computation power can be significantly reduced without significant performance degradation. The proposed architecture is designed and verified by Verilog HDL, and implemented into 0.13um CMOS standard cell and Xilinx FPGA circuits for the estimation of hardware complexity and computation power. From the results of the implementations, we can find that the proposed circuits reduces the hardware complexity by about 43% and the estimated computation power by about 23%, respectively, compared to the architecture employing the original MUSIC algorithm.

Output SINR Analysis of GPS Adaptive Interference Canceler Based on Modified Despreader (변형된 역확산기 기반의 GPS 적응 간섭제거기의 출력 SINR 해석)

  • Hwang, Suk-Seung
    • The Journal of the Korea institute of electronic communication sciences
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    • v.9 no.2
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    • pp.195-202
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    • 2014
  • The Global Positioning System (GPS), which has various military and commercial applications, is designed to estimate the location of the specific user or object. In order to accurately estimate the location, GPS requires at least four satellite signals. The GPS receiver operates on extremely low signal-to-noise ratio (SNR) environment and it may suffer from various interference signals with the extremely high power. In this paper, we introduce a blind adaptive receiver based on the modified despreader, which suppress interference signals and detect GPS signals of interest without requiring explicit angle-of-arrival (AOA) information. We, also, provide the mathematical analysis for the signal-to-interference and noise ratio (SINR) of the modified despeader beamformer output. A representative computer simulation example is presented to illustrate the interference suppression performance of the considered GPS receiver and mathematical analysis of the SINR.

Eigen-Analysis Based Super-Resolution Time Delay Estimation Algorithms for Spread Spectrum Signals (대역 확산 신호를 위한 고유치 해석 기반의 초 분해능 지연 시간 추정 알고리즘)

  • Park, Hyung-Rae;Shin, Joon-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.12
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    • pp.1013-1020
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    • 2013
  • In this paper the super-resolution time delay estimation algorithms based on eigen-analysis are developed for spread spectrum signals along with their comparative performance analysis. First, we shall develop super-resolution time delay estimation algorithms using the representative eigen-analysis based AOA (angle-of-arrival) estimation algorithms such as MUSIC, Minimum-Norm, and ESPRIT, and apply them to the ISO/IEC 24730-2.1 real-time locating system (RTLS) employing a direct sequence spread spectrum (DS-SS) technique to compare their performances in RTLS environments. Simulation results illustrate that all the three algorithms can resolve multipath signals whose delay differences are even smaller than the Rayleigh resolution limit. Simulation results also show that MUSIC and Minimum-Norm provide a similar performance while ESPRIT is inferior to both algorithms in RTLS environments.