• Journal of Biomedical Engineering Research
• /
• v.3 no.1
• /
• pp.35-42
• /
• 1982

The objective of this phantom study is to develop a digital method for improving the lateral resolution of B-scan ultrasonographic images irs medical application of ultrasound. By utilizing a discrete state-space modeling approach and Kalman-Buch method for analysis of the transducer's beam profile and the measurement and sampling noise, a stable recursive restoration of the object image was obtained for improved lateral resolution. The point spread function (PSF) was measured for the reflective signals after scanning the small pins located along the depth of interest. One major advantage of the present recursive scheme over the transform method is in its applicability for the space-variant imaging, such as in the case of the rotational movement of transducer.

• Bulletin of the Korean Space Science Society
• /
• 1993.04a
• /
• pp.19-19
• /
• 1993

위성의 실제 궤도를 실시간하에서 추정(real-time estimation)하기 위해 지구 비대칭 중력장, 지구 대기의 저항력,그리고, 태양과 달의 위성체에 대한 섭동의 영향을 받는 지구 근방의 위성을 동력학적 모델로 선택하였다. 위성 관측소에서 얻게될 가상의 위성 궤도 자료들은 실제 관측에서 나타날 수 있는 관측 잡음(measurement noise)뿐 아니라 추적소 고도 등의 불확실한 요소들을 포함한다. 또한 수치 모델에서 고려치 못한 섭적 난수에 의해 만들었다. 확장 칼만 필터(Extended Kalman Filter)의 특성을 알아 보기 위해 일차원에서의 자유낙하체에 대한 거리와 속도 추정의 모의 실험을 비교하였고, 뱃치추정 알고리즘, 순차 추정 알고리즘의 모의 실험이 거리변화율의 자료를 이용하여 확장 칼만 필터와 비교하였다. 그 결과, 확장 칼만 필터 알고리즘은 빠른 수렴 속도를 갖는 특성을 가지며, 실시간하에서 완전하지 못한 수치 모델로 실제 궤도를 결정하고 궤도 요소를 추정하는데 효과적임을 알 수 있다.

• Journal of Computing Science and Engineering
• /
• v.6 no.4
• /
• pp.310-319
• /
• 2012

Next generation wireless receivers demand low computational complexity algorithms with high computing power in order to perform fast signal detections and error estimations. Several signal detection and estimation algorithms have been proposed for next generation wireless receivers which are primarily designed to provide reasonable performance in terms of signal to noise ratio (SNR) and bit error rate (BER). However, none of them have been chosen for direct implementation as they offer high computational complexity with relatively lower computing power. This paper presents a low-complexity power-efficient algorithm that improves the computing power and provides relatively faster signal detection for next generation wireless multiuser receivers. Measurement results of the proposed algorithm are provided and the overall system performance is indicated by BER and the computational complexity. Finally, in order to verify the low-complexity of the proposed algorithm we also present a formal mathematical proof.

• Structural Engineering and Mechanics
• /
• v.17 no.3_4
• /
• pp.445-466
• /
• 2004

In this paper, several modal identification techniques for output-only structural systems are extensively investigated. The methods considered are the power spectral method, the frequency domain decomposition method, the Ibrahim time domain method, the eigensystem realization algorithm, and the stochastic subspace identification method. Generally, the power spectral method is most widely used in practical area, however, the other methods may give better estimates particularly for the cases with closed modes and/or with large measurement noise. Example analyses were carried out on typical structural systems under three different loading cases, and the identification performances were examined throught the comparisons between the estimates by various methods.

• Korean Management Science Review
• /
• v.29 no.3
• /
• pp.1-11
• /
• 2012

This paper considers a localization problem in time difference of arrival (TDOA)-based radio frequency identification (RFID) systems. To estimate the position of a target tag, this paper suggests three localization algorithms that use benchmark tags. The benchmark tags are the same type as the target tag, but either the locations or distance of the benchmark tags are known. Two algorithms use the benchmarks for auxiliary information to improve the estimation accuracy of the other localization algorithms such as least squared estimator (LSE). The other one utilizes the benchmarks as essential tags to estimate the location. Numerical tests show that the localization accuracy can be improved by using benchmark tags especially when an algorithm using the LSE is applied to the localization problem. Furthermore, this paper shows that our benchmark algorithm is valuable when the measurement noise is large.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.7
• /
• pp.1529-1533
• /
• 2005

In this paper designed available pre-amplifier to Intrabroadband power amplifier. Designed pre-amplifier used WJ company's AMI which frequency characteristic and noise characteristic are superior. Designed to have superior VSWR characteristic and frequency characteristic covering broadband of 100MHz ${\~}$ 3GHz using feedback. Designed ye-amp broadband special qualify such as EMC measurement equipment roll important position do to utilize to power amplifier of equipment that how consider.

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.738-741
• /
• 2004

The overall performance of AC servo system is greatly affected by the uncertainties of unpredictable mechanical parameter variations and external load disturbances. Therefore, to compensate this problem, it is necessary to know different parameters and load disturbances subjected to position/speed control. This paper proposes an online identification method of mechanical parameters/load disturbances for AC servo system using Support Vector Regression (SVR). The proposed methodology advocates analytic parameter regression directly from the training data, rather than adaptive controller and observer approaches commonly used in motion control applications. The experimental results demonstrate that the proposed SVR algorithm is appropriate for control of unknown servo systems even with large measurement noise.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.53 no.11
• /
• pp.786-792
• /
• 2004

A wavelet based ECG data compression has become an attractive and efficient method in many mobile tele-cardiology applications. But large data size required for high compression performance leads a serious delay. In this paper, new wavelet compression method with minimum delay is proposed. It is based on deciding the type and compression ratio(CR) of block organically according to the standard deviation of input ECG data with minimum block size. Compression performances of the proposed algorithm for different MIT ECG Records were analyzed comparing other ECG compression algorithm. In addition to the processing delay measurement, compression efficiency and reconstruction sensitivity to error were also evaluated via random noise simulation models. The results show that the proposed algorithm has both lower PRD than other algorithm on same CR and minimum time in the data acquisition, processing and transmission.

• Proceedings of the KIEE Conference
• /
• 1999.11c
• /
• pp.552-554
• /
• 1999

In this paper, a robust control system with the disturbance observer is proposed for BLDC servo system. The overall control system consists of the speed controller which is implemented with PI controller and the disturbance observer with free parameters. The proposed control system is designed the command input response and the closed loop characteristics independently by using two-degrees-of-freedom concept, so it can improve the closed loop characteristics with no influence on the command input response. The effective suppression of disturbance with the observer improves the characteristics of the closed loop of the system. And also, by fluting the bandwidth of free parameters, measurement noise is considered. To verify the better performance of the proposed control system than that of the conventional PI controllers, the performance of the controller is analyzed theoretically and some simulation results are presented.

• Proceedings of the KIEE Conference
• /
• 2000.07a
• /
• pp.564-566
• /
• 2000

To provide more noiseless upstream service on the HFC(Hybrid-Fiber Coaxial) Access Network, we should conduct upstream band analysis and have related operation skill. In this paper, we studied the upstream signal measurement to get goof transmission quality, effective operation and maintenance, also showed the method of noise analysis and that of upstream band frequency selection. Finally we tested the signal in the field and showed the analyzed result.