• Title, Summary, Keyword: estimation

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A Low-Complexity 2-D MMSE Channel Estimation for OFDM Systems (OFDM 시스템을 위한 낮은 복잡도를 갖는 2-D MMSE 채널 추정 기법)

  • Kim, Jung-In;Jang, Jun-Hee;Choi, Hyung-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.5C
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    • pp.317-325
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    • 2011
  • For OFDM (Orthogonal Frequency Division Multiplexing) systems, 2-D MMSE (2-Dimensional Minimum Mean Square Error) channel estimation provides optimal performance in frequency/time selective fading channel environment. However, the 2-D MMSE channel estimation has high computational complexity due to the large matrix size, because the 2-D MMSE channel estimation considers time as well as frequency axis for channel estimation. To reduce the computational complexity, we propose a modified 2-D MMSE channel estimator which is based on 1-D MMSE channel estimation with weighted sum. Furthermore, we consider RMS delay spread and Doppler frequency estimation for 2-D MMSE channel estimation. We show that the proposed method can significantly reduce computational complexity as well as that it can perform close to 2-D MMSE channel estimation.

A Study on the Mid-Long Term Direction for Development of Software Cost Estimation Guidelines (소프트웨어 사업대가기준 중장기 발전 방향에 관한 연구)

  • Kim, Woo-Je;Kwon, Moon-Ju
    • The Journal of Society for e-Business Studies
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    • v.15 no.1
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    • pp.139-155
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    • 2010
  • The purpose of this paper is to develop a framework of software cost estimation guidelines and to derive a mid-long term direction for development of the software cost estimation guidelines. In this paper, all the steps in the software life cycle are researched in the view of cost estimation, and current software cost estimation guidelines and models have been reviewed and analysed first. Second, a plan to separate unit cost per function point from standard procedure in current software cost estimation guidelines is presented to strengthen maket self-regulating function as a mid-long term developmental direction for software cost estimation guidelines. Third, construction of cost repository, making standard procedure for software cost estimation guidelines, development of various kinds of software cost estimation models, and a system for experts on software cost estimation are presented as the prerequisites for the future model framework of software cost estimation guidelines. Finally a roadmap for establishing the future model is proposed.

Least Square Channel Estimation Scheme of OFDM System using Fuzzy Inference Method (퍼지 추론법을 적용한 OFDM 시스템의 LS(Least Square) 채널추정 기법)

  • Kim, Nam;Choi, Jung-Hun
    • The Journal of the Korea Contents Association
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    • v.9 no.5
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    • pp.84-90
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    • 2009
  • In this paper, the new channel estimation was proposed that have the low complexity and high performance using Fuzzy inference method uses recently from various field for estimation about uncertainty in channel estimation of OFDM. Proposed method is channel estimation performance improve, calculation and interpolation for statistics character of channel using the pilot before LS channel estimation by Fuzzy inference method. Simulation result in QPSK proposed channel estimation method shows the enhancement of 5.5dB compared to the LS channel estimation and the deterioration of 1.3dB compared to the MMSE channel estimation in mean square error point $10^{-3}$. symbol error rate shows similarity performance the MMSE $10^{-1.96}$, proposed channel estimation $10^{-1.93}$ and enhancement of $10^{-0.35}$ compared to the LS channel estimation in signal to noise ratio point 20dB.

Robust Ultrasound Multigate Blood Volume Flow Estimation

  • Zhang, Yi;Li, Jinkai;Liu, Xin;Liu, Dong Chyuan
    • Journal of Information Processing Systems
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    • v.15 no.4
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    • pp.820-832
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    • 2019
  • Estimation of accurate blood volume flow in ultrasound Doppler blood flow spectrograms is extremely important for clinical diagnostic purposes. Blood volume flow measurements require the assessment of both the velocity distribution and the cross-sectional area of the vessel. Unfortunately, the existing volume flow estimation algorithms by ultrasound lack the velocity space distribution information in cross-sections of a vessel and have the problems of low accuracy and poor stability. In this paper, a new robust ultrasound volume flow estimation method based on multigate (RMG) is proposed and the multigate technology provides detail information on the local velocity distribution. In this method, an accurate double iterative flow velocity estimation algorithm (DIV) is used to estimate the mean velocity and it has been tested on in vivo data from carotid. The results from experiments indicate a mean standard deviation of less than 6% in flow velocities when estimated for a range of SNR levels. The RMG method is validated in a custom-designed experimental setup, Doppler phantom and imitation blood flow control system. In vitro experimental results show that the mean error of the RMG algorithm is 4.81%. Low errors in blood volume flow estimation make the prospect of using the RMG algorithm for real-time blood volume flow estimation possible.

Variable Block Size Motion Estimation Techniques for The Motion Sequence Coding (움직임 영상 부호화를 위한 가변 블록 크기 움직임 추정 기법)

  • 김종원;이상욱
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.30B no.4
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    • pp.104-115
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    • 1993
  • The motion compensated coding (MCC) technique, which exploits the temporal redundancies in the moving images with the motion estimation technique,is one of the most popular techniques currently used. Recently, a variable block size(VBS) motion estimation scheme has been utilized to improve the performance of the motion compensted coding. This scheme allows large blocks to the used when smaller blocks provide little gain, saving rates for areas containing more complex motion. Hence, a new VBS motion estimation scheme with a hierarchical structure is proposed in this paper, in order to combine the motion vector coding technique efficiently. Topmost level motion vector, which is obtained by the gain/cost motion estimation technique with selective motion prediction method, is always transmitted. Thus, the hierarchical VBS motion estimation scheme can efficiently exploit the redundancies among neighboring motion vectors, providing an efficient motion vector encoding scheme. Also, a restricted search with respect to the topmost level motion vector enables more flexible and efficient motion estimation for the remaining lower level blocks. Computer simulations on the high resolution image sequence show that, the VBS motion estimation scheme provides a performance improvement of 0.6~0.7 dB, in terms of PSNR, compared to the fixed block size motion estimation scheme.

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Online Estimation of Rotational Inertia of an Excavator Based on Recursive Least Squares with Multiple Forgetting

  • Oh, Kwangseok;Yi, Kyong Su;Seo, Jaho;Kim, Yongrae;Lee, Geunho
    • Journal of Drive and Control
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    • v.14 no.3
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    • pp.40-49
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    • 2017
  • This study presents an online estimation of an excavator's rotational inertia by using recursive least square with forgetting. It is difficult to measure rotational inertia in real systems. Against this background, online estimation of rotational inertia is essential for improving safety and automation of construction equipment such as excavators because changes in inertial parameter impact dynamic characteristics. Regarding an excavator, rotational inertia for swing motion may change significantly according to working posture and digging conditions. Hence, rotational inertia estimation by predicting swing motion is critical for enhancing working safety and automation. Swing velocity and damping coefficient were used for rotational inertia estimation in this study. Updating rules are proposed for enhancing convergence performance by using the damping coefficient and forgetting factors. The proposed estimation algorithm uses three forgetting factors to estimate time-varying rotational inertia, damping coefficient, and torque with different variation rates. Rotational inertia in a typical working scenario was considered for reasonable performance evaluation. Three simulations were conducted by considering several digging conditions. Presented estimation results reveal the proposed estimation scheme is effective for estimating varying rotational inertia of the excavator.

Comparison of Benefit Estimation Models in Cost-Benefit Analysis: A Case of Chronic Hypertension Management Programs

  • Lim, Ji-Young;Kim, Mi-Ja;Park, Chang-Gi;Kim, Jung-Yun
    • Journal of Korean Academy of Nursing
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    • v.41 no.6
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    • pp.750-757
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    • 2011
  • Purpose: Cost-benefit analysis is one of the most commonly used economic evaluation methods, which helps to inform the economic value of a program to decision makers. However, the selection of a correct benefit estimation method remains critical for accurate cost-benefit analysis. This paper compared benefit estimations among three different benefit estimation models. Methods: Data from community-based chronic hypertension management programs in a city in South Korea were used. Three different benefit estimation methods were compared. The first was a standard deterministic estimation model; second, a repeated-measures deterministic estimation model; and third, a transitional probability estimation model. Results: The estimated net benefit of the three different methods were $1,273.01, $-3,749.42, and $-5,122.55 respectively. Conclusion: The transitional probability estimation model showed the most correct and realistic benefit estimation, as it traced possible paths of changing status between time points and it accounted for both positive and negative benefits.

A Study on 3D Data Model Development by Normalizing and Method of its Effective Use - Focused on Building Interior Construction - (정규화를 통한 3차원 데이터 모델 구축 및 활용성 향상 방안 연구 -건축 마감 공사 중심으로 -)

  • Lee, Myoung-Hoon;Ham, Nam-Hyuk;Kim, Ju-Hyung;Kim, Jae-Jun
    • Journal of The Korean Digital Architecture Interior Association
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    • v.10 no.3
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    • pp.11-18
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    • 2010
  • Cost estimation through fast and correct quantity take offs are crucial in the process of construction project. The existing methods for cost estimation are mainly based on 2D-based drawings and the estimation result tends to be different according to the estimator's experience, the quality and quantity of used information and estimation time. To solve these problems, the domestic construction industry have recently tried to use the data extracted from 3D data modeling based on BIM(Building Information Modeling) in order to achieve more accurate and objective cost estimation. However it tends to increase dramatically the quantity of information that can be used in cost estimation by estimators. Therefore in order to achieve quality information data from 3D data modeling, the characteristics of the project should be reflected on the 3D model and it is most important to extract information only for cost estimation from the whole 3D model fast and accurately. Thus this study aims to propose the 3D modeling method through Data Normalization which maximizes the usability of 3D Data modeling in cost estimation process.

An Average-Weighted Angle of Arrival Parameter Estimation Technique for Wireless Positioning based on IEEE 802.15.3a (IEEE 802.15.3a 기반의 무선 위치인식을 위한 평균가중 신호 도착방향 매개변수 추정 기법)

  • Baang, Sung-Keun;Lee, Yong-Up
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.5C
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    • pp.472-478
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    • 2010
  • In the environment of wireless communication system of IEEE 802.15.3a UWB standard, the angle of arrival(AOA) estimation technique for the indoor wireless positioning algorithms, based on the AOA parameter estimation which fits well for the wireless communication channel and shows high estimation accuracy, is proposed. After the UWB signal model, based on the IEEE 802.1.3a standard, is constructed, the average weighted MUSIC technique is proposed, which shows better estimation accuracy than those of conventional estimation technique. Through the simulation studies, the environment of the indoor wireless positioning system including the IEEE 802.15.3a channel is configured and we demonstrate better estimation results by the proposed AOA estimation technique than those from the conventional method.

A Study on the Improvement of Website Evaluation Method through AHP Approach (AHP 접근방법을 통한 웹사이트 유형별 평가기법 개선에 관한 연구)

  • Kim, Dae-Jin;Kim, Jin-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.7
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    • pp.2420-2435
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    • 2010
  • This study presented estimation framework that consider website pattern and user use purpose for website estimation improvement. Also, analyzed and evaluated existing website using estimation framework. In this study, divided by general user and company user and analyzed relative importance between each estimation factors in estimation framework and secured reliability of website estimation model because applies AHP method and presented key factors to website construction, operation, administration. Through this study, projected necessity of weight calculation between estimation area by site type to website estimation field researchers and differentiate contents offered that follow in user type(individual, company) to website planners and operators, projected guideline that can provide more efficient and strategic service.