• Title/Summary/Keyword: 직교모델

Search Result 247, Processing Time 0.025 seconds

Performance Analysis of Dualrate MC-CDMA Systems Based on Code Grouping (코드그룹화에 의한 이중전송률 MC-CDMA 시스템의 성능분석)

  • Kim, Nam-Sun
    • Journal of Korea Society of Industrial Information Systems
    • /
    • v.11 no.4
    • /
    • pp.112-120
    • /
    • 2006
  • Multicarrier code division multiple access(MC-CDMA) system that combines multicarrier modulation with CDMA offers robustness to frequency selective fading and can support higher rate data transmission with higher spectral efficiency. A new asynchronous MC-CDMA system to implement multiple data rate communications is proposed in this paper. In a W-CDMA downlink the orthogonal variable spreading factor(OVSF) code is used for variable spreading factor for various multimedia traffic. Proposed system utilizes the OVSF code that generated by generation property for spreading. The proposed MC-CDMA system use different lengths of OVSF code as a spreading code according to their data rate. The groupwise processing is accomplished by code grouping in OVSF code generation tree. For the analysis of average BER performance, numerical method and computer simulation were used. We also compare the system performance with that of a single rate MC-CDMA system used orthogonal code as a spreading code.

  • PDF

Frequency Division Concurrent Sensing Method for High-Speed Detection of Large Touch Screens (대형 터치스크린의 고속감지를 위한 주파수분할 동시센싱 기법)

  • Jang, Un-Yong;Kim, HyungWon
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.19 no.4
    • /
    • pp.895-902
    • /
    • 2015
  • This paper presents a high-speed sensing and noise cancellation technique for large touch screens, which is called FDCS (Frequency Division Concurrent Sensing). Most conventional touch screen detection methods apply excitation pulses sequentially and analyze the sensing signals sequentially, and so are often unacceptably slow for large touch screens. The proposed technique applies sinusoidal signals of orthogonal frequencies simultaneously to all drive lines, and analyzes the signals from each sense line in frequency domain. Its parallel driving allows high speed detection even for a very large touch screens. It enhances the sensing SNR (Signal to Noise Ratio) by introducing a frequency domain noise filtering scheme. We also propose a pre-distortion equalizer, which compensates the drive signals using the inverse transfer function of touch screen panel to further enhance the sensing SNR. Experimental results with a 23" large touch screen show that the proposed technique enhances the frame scan rate by 273% and an SNR by 43dB compared with a conventional scheme.

Comparison of Ensemble Perturbations using Lorenz-95 Model: Bred vectors, Orthogonal Bred vectors and Ensemble Transform Kalman Filter(ETKF) (로렌쯔-95 모델을 이용한 앙상블 섭동 비교: 브레드벡터, 직교 브레드벡터와 앙상블 칼만 필터)

  • Chung, Kwan-Young;Barker, Dale;Moon, Sun-Ok;Jeon, Eun-Hee;Lee, Hee-Sang
    • Atmosphere
    • /
    • v.17 no.3
    • /
    • pp.217-230
    • /
    • 2007
  • Using the Lorenz-95 simple model, which can simulate many atmospheric characteristics, we compare the performance of ensemble strategies such as bred vectors, the bred vectors rotated (to be orthogonal to each bred member), and the Ensemble Transform Kalman Filter (ETKF). The performance metrics used are the RMSE of ensemble means, the ratio of RMS error of ensemble mean to the spread of ensemble, rank histograms to see if the ensemble member can well represent the true probability density function (pdf), and the distribution of eigen-values of the forecast ensemble, which can provide useful information on the independence of each member. In the meantime, the orthogonal bred vectors can achieve the considerable progress comparing the bred vectors in all aspects of RMSE, spread, and independence of members. When we rotate the bred vectors for orthogonalization, the improvement rate for the spread of ensemble is almost as double as that for RMS error of ensemble mean compared to the non-rotated bred vectors on a simple model. It appears that the result is consistent with the tentative test on the operational model in KMA. In conclusion, ETKF is superior to the other two methods in all terms of the assesment ways we used when it comes to ensemble prediction. But we cannot decide which perturbation strategy is better in aspect of the structure of the background error covariance. It appears that further studies on the best perturbation way for hybrid variational data assimilation to consider an error-of-the-day(EOTD) should be needed.

Approximate Multi-Objective Optimization of A Wall-mounted Monitor Bracket Arm Considering Strength Design Conditions (강도조건을 고려한 벽걸이 모니터 브라켓 암의 다중목적 근사최적설계)

  • Doh, Jaehyeok;Lee, Jongsoo
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.39 no.5
    • /
    • pp.535-541
    • /
    • 2015
  • In this study, an approximate multi-objective optimization of a wall-mounted monitor bracket arm was performed. The rotation angle of the bracket arm was determined considering the inplane degree of freedom. We then formulated an optimization problem on maximum stress and deflection. Analyses of mean and design parameters were conducted for sensitivity regarding performance with orthogonal array and response surface method (RSM). RSM models of objective and constraint functions were generated using central composite (CCD) and D-optimal design. The accuracy of approximate models was evaluated through $R^2$ value. The obtained optimal solutions by non-dominant sorting genetic algorithm (NSGA-II) were validated through the finite element analysis and we compared the obtained optimal solution by CCD and D-optimal design.

SOFTWARE DEVELOPMENT OF HIGH-PRECISION EPHEMERIDES OF SOLAR SYSTEM (II) (태양계 행성의 고정확도 위치계산에 과한 연구(II))

  • 신종섭;안영숙;박필호;박은광;박종옥
    • Journal of Astronomy and Space Sciences
    • /
    • v.12 no.1
    • /
    • pp.78-89
    • /
    • 1995
  • We solved n-body problem about 9 planets, moon, and 4 minor planets with relativistic effect related to the basic equation of motion of the solar system. Perturbations including flgure potential of the earth and the moon and solid earth tidal effect were considered on this relativistic equation of motion. The orientations employed precession and nutation for the earth, and lunar libration model with Eckert's lunar libration model based on J2000.0 were used for the moon. Finally, we developed heliocentric ecliptic position and velocity of each planet using this software package named the SSEG (Solar System Ephemerides Generator) by long-term (more than 100 years) simulation on CRAY-2S super computer, through testing each subroutine on personal computer and short-time(within 800 dyas) running on SUN3/280 workstation. Epoch of input data JD2440400.5 were adopted in order to compare our results to the data archived from JPL's DE 200 by Standish and Newhall. Above equation of motion was integrated numerically having 1-day step-size interval through 40,000 days (about 110 years long) as total computing interval. We obtained high-precision ephemerides of the planets with maximum error, less $than\pm2\times10^{-8}AU(\approx\pm3km)$ compared with DE200 data (except for mars and moon).

  • PDF

Performance Analysis of Multirate MC-CDMA Systems using OVSF Code Grouping (OVSF 코드그룹화를 이용한 다중전송률 MC-CDMA 시스템의 성능분석)

  • Kim, Nam-Sun
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.31 no.12C
    • /
    • pp.1135-1142
    • /
    • 2006
  • This article presents a new asynchronous MC-CDMA system to implement multiple data rate communications. In a W-CDMA downlink, the OVSF code is used for spreading code for various multimedia traffic. Proposed system utilizes the OVSF code that generated by generation property for spreading. The proposed MC-CDMA system use different lengths of OVSF code as a spreading code according to their data rate. The groupwise processing is accomplished by code grouping in OVSF code generation tree. Between each group, the code grouping interference canceller is performed to cancel other group interference. At that time the proposed receiver does not require any information about interference users. For the analysis of average BER performance, we propose system model and computer simulation were used. We also compare the system performance with that of a single rate MC-CDMA system used orthogonal code as a spreading code.

Construction of Static 3D Ultrasonography Image by Radiation Beam Tracking Method from 1D Array Probe (1차원 배열 탐촉자의 방사빔추적기법을 이용한 정적 3차원 초음파진단영상 구성)

  • Kim, Yong Tae;Doh, Il;Ahn, Bongyoung;Kim, Kwang-Youn
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.35 no.2
    • /
    • pp.128-133
    • /
    • 2015
  • This paper describes the construction of a static 3D ultrasonography image by tracking the radiation beam position during the handy operation of a 1D array probe to enable point-of-care use. The theoretical model of the transformation from the translational and rotational information of the sensor mounted on the probe to the reference Cartesian coordinate system was given. The signal amplification and serial communication interface module was made using a commercially available sensor. A test phantom was also made using silicone putty in a donut shape. During the movement of the hand-held probe, B-mode movie and sensor signals were recorded. B-mode images were periodically selected from the movie, and the gray levels of the pixels for each image were converted to the gray levels of 3D voxels. 3D and 2D images of arbitrary cross-section of the B-mode type were also constructed from the voxel data, and agreed well with the shape of the test phantom.

Adaptive Channel Estimation Algorithm for DVB-T (DVB-시스템을 위한 적응형 채널 추정 알고리즘)

  • Kim, Seung-Hwan;Lee, Jin-Beom;Lee, Jin-Yong;Kim, Young-Lok
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.6A
    • /
    • pp.676-684
    • /
    • 2008
  • In digital video broadcasting-terrestrial (DVB-T), which is the European digital terrestrial television standard, the orthogonal frequency division multiplexing (OFDM) has been adopted for signal transmission. The main reasons using OFDM are to increase the robustness against the frequency selective fading and impulse noise, and to use available bandwidth efficiently. However, channel variation within an OFDM symbol destroys orthogonality between subcarriers, resulting in inter-carrier interference (ICI), which increases an error floor in proportional to maximum Doppler spread. This paper provides an ICI analysis in both time and frequency domains while existing literatures analyze the ICI effects mainly in frequency domain and proposes the algorithms that estimate the channel impulse response and channel variation using least square (LS) algorithm which is the most simple channel estimation technique. And we propose adaptive channel estimation algorithm that estimates the velocity of terminals. The simulation results show that proposed algorithm has similar performance with about 1.5% computational complexity of noise and ICI reduction LS algorithm in low speed environments.

A Sham Experiment for the Measurement of Nonlinear Pulse Propagation Characteristics of Blood Vessel Using Bispectral Analysis (바이스펙트럼해석을 이용한 혈관의 비선형 맥동전파특성 계측에 대한 모의실험)

  • 장경영;김경조
    • Journal of Biomedical Engineering Research
    • /
    • v.16 no.4
    • /
    • pp.525-532
    • /
    • 1995
  • In this paper, a new try to measure nonlinear propagation characteristics of the pulse along blood vessel by using bispectral analysis is introduced, and the possibility of its application to the medical diagnosis is shown. In this method, the waveforms of pulse motion of blood vessel at two separated measuring points on the wall were detected from Doppler frequency modulation of transmitted probing ultrasonic waves. Then the auto- and crossbispectrum of detected waveforms are calculated to estimate the quadratic NTF (nonlinear transfer function) between the two measuring positions. In order to show relationships between the NTF and the nonlinear propagation characteristics, computer simulations have been performed. As the propagation distance increases, harmonic frequency components in NTF increases broadly due to the nonlinear effect in the propagation of blood pulse. In order to represent this phenomena quantitatively, we propose a new parameter, dispersion ratio of WTF. Basic experimental system was constructed by using 3.5MHz probing ultrasonic waves and the preliminary experiments were carried out on ague phantom and human body. Experimental results showed the validity of the measurement system enoughly.

  • PDF

Strength Assessment of LNG CCS using Strength Analysis Method for Composite Materials (직교이방성 복합재료의 극저온 재료 물성치를 고려한 LNG CCS의 강도 평가에 관한 연구)

  • Jeong, Han Koo;Yang, Young Soon
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.51 no.2
    • /
    • pp.114-121
    • /
    • 2014
  • Liquefied natural gas(LNG) cargo containment system(CCS) has the primary function of ensuring both adequate structural safety with respect to sloshing load which is defined as a violent behaviour of the liquid contents in CCS due to external forced motions and thermal insulation keeping natural gas below its boiling point. Among different LNG CCS types such as independent B-type and membrane ones, Mark III CCS is considered in this paper to perform its strength assessment. Mark III CCS plate is designed and constructed by stacking various non-metallic engineering materials such as plywood, triplex, reinforced PU foam that are supported by series of mastic upon inner steel hull structure. From the viewpoint of structural analysis, this plated structure is treated as a laminated composite structure showing complex structural behaviour under external load. Advanced finite element models of Mark III CCS plate is generated and used in conjunction with ultimate strength based failure criteria from laminated composite mechanics for the strength assessment. The strength assessment is performed within the initial failure state of Mark III CCS plate. Results provide failure details such as failure locations and loads. Finally obtained results are reviewed using the loads from acceptance criteria suggested by classification.