• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.45-52
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• 2002

This paper presents fault detection scheme of Brushless DC(BLDC) motor drive system by estimating BLDC motor resistance using motor input and output data which is transmitted from data acquisition board to host computer over serial communication channel. Since communication time delay has a serious effect on performance, we use periodic and fixed communication protocol. Hence, the delay time is priory known. Simplified BLDC motor model and recursive least square algorithm is used for estimating motor resistance. By experiment result, we confirm the proposed scheme.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06a
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• pp.87-90
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• 1998

움직임 열화(motion blur)현상은 카메라와 피사체간의 상대적임 움직임에 발생되는 영상의 번짐 현상으로, 본 논문에서는 새롭게 제시한, 노이즈의 분산을 산출해 내기 위한 노이즈 지배영역과, 움직임 열화와 각도와 길이를 추정해내기 위한 신호 지배영역을 통하여 움직임 열화의 파라메터를 효율적으로 추정할 수 있는 방법을 제시하였다. 또한, 새롭게 제안한 가변가중치(weight)를 적용한 최소자승법(Least Man Square)은 극점 자취의 방향 추정에 있어 정밀한 측정이 가능케 한다. 열화의 방향이 얻어지면, 1차원 셉스트럼(Cepstrum)방법으로 빠르게 움직임 열화의 길이를 구할 수 있게 된다. 이러한 방법으로 얻어진 정보들을 이용하여, 실제 손상되어진 영상을 효과적으로 복원할 수 있었다.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2017-2019
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• 2003

열악한 환경에서 동작해야 하거나 물리적 접근이 어려운 곳에 장착되는 센서 시스템의 경우, 유선에 의한 정보전달이 어려울 뿐만 아니라 센서 내 전원설비가 제한적인 수도 있다. 따라서 본 논문에서는 이러한 문제점에 대한 해결책으로서 밧데리없이 유도결합에 의하여 원격 센서로부터 정보 취득이 가능한 한 방법을 제안하였다. 이 방법은 전원공급에 의한 유도 결합식의 원격 센서 시스템과는 달리, 원격 센서의 정전용량을 변 복조 과정 없이 재귀적 최소 자승 추정법에 의해 센서의 정전용량을 고정도로 추정하는 것이다. 이를 위하여 시 스템의 유도결합 모델을 사용하였으며, 모델 파라미터가 시간에 따라 변화하는 경우에는 망각률을 사용하여 정확도가 높은 원격 센서 시스템을 구현할 수 있었다.

• Journal of Korea Water Resources Association
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• v.41 no.9
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• pp.943-958
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• 2008

This study employs Bayesian regression analysis for fitting discharge rating curves. The parameter estimates using the Bayesian regression analysis were compared to ordinary least square method using the t-distribution. In these comparisons, the mean values from the t-distribution and the Bayesian regression are not significantly different. However, the difference between upper and lower limits are remarkably reduced with the Bayesian regression. Therefore, from the point of view of uncertainty analysis, the Bayesian regression is more attractive than the conventional method based on a t-distribution because the data size at the site of interest is typically insufficient to estimate the parameters in rating curve. The merits and demerits of the two types of estimation methods are analyzed through the statistical simulation considering heteroscedasticity. The validation of the Bayesian regression is also performed using real stage-discharge data which were observed at 5 gauges on the Anyangcheon basin. Because the true parameters at 5 gauges are unknown, the quantitative accuracy of the Bayesian regression can not be assessed. However, it can be suggested that the uncertainty in rating curves at 5 gauges be reduced by Bayesian regression.

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.25-31
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• 2002

A system identification method is introduced to increase the prediction accuracy of a ship's maneuverability in PMM test, analysis. To improve the accuracy of linear hydrodynamic coefficients, the analysis techniques of pure sway and yaw tests are developed, and confirmed. In the analysis of sway tests, accuracy to linear hydrodynamic coefficients depends on the frequency of sway motion. To obtain nonlinear hydrodynamic coefficients for large drift angles, a combined yaw test is introduced. Using this system identification method, runs of PMM test can be reduced while retaining sufficient accuracy, compared to the Fourier integration method. Through the comparisons with sea trial results and the Fourier integration method, the accuracy and efficiency of the newly proposed system identification method, based on least square method, has been validated.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.10
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• pp.60-67
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• 1990

This paper proposes a model-based fault detection method for linear/nonlinear system having modelling errors, nonlinearities and measurement noise. The system model is represented by the unified operator [5] in order to apply to both the continuous-time and discrete-time problems. The fault detection method suggested here accounts for the effects of noise, model mismatch and nonlinearities. Modelling errors are depicted by additive forms and the nominal model denominator is fixed via prior experiments in order to quantify the nucertainty bound on the parameter estima-tion. The least square method is used to estimate the numerator parameters of the nominal model. performance than traditional methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.153-160
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• 2011

Recently there are many long span cable supported bridges like Cable Stayed Bridge and Suspension Bridge already constructed or planned. Reconsidering of proper design wind load of long span bridge is required since the meteorological value based on the data only from 1960s to 1995 has been used when we estimate the wind load for designing long span bridges. In this paper, the research area was confined to western and southern coasts where many long span bridges have constructed. The method of moment and the least-squares method were used to estimate the expected wind speeds of 100 year's return period for girder bridges and for 200 year's return period for long span bridges based on the Gumbel's distribution. As the return-period wind speed on the land face was revised because of recent high speed velocity, the revised return-period wind speed is increased by 17%. Compatibility of return-period wind speed was also evaluated using RMS (Root Mean Square) error method. Aa a result of this paper, the least-squares method is more compatible than the method of moment in the case of western and southern coasts in Korea.

• Current Research on Agriculture and Life Sciences
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• v.9
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• pp.37-49
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• 1991

This study was conducted to estimate the effects of year, age of dam at calving, farm and lactation period on milk yield with the data of 4,008 cows' records which were collected at 32 farms by Korea Animal Improvement Association from 1985 to 1989. The results obtained in this study are summarized as follows: 1. The average performance of the dairy cattle in the study were $5,959.23{\pm}2,113.03kg$ in actual milk yield, $49.19{\pm}22.77$ months in age of dam at calving, $27.11{\pm}5.13$ months in age at first calving and $255.11{\pm}79.68$ days in lactation period. 2. The percentages of variance component for different sources were 29.39% for the residuals, 1.91% for years, 4.86% for age at calving, 8.89% for farms and 54.94% for lactation period. 3. The overall mean of least-square estimate on the milk yield was 6,229.31kg. In the effects of year, the least-square means of milk yield were estimated 6,000.76kg in 1985-1987, 6,028.11kg in 1988 and 6,659.07kg in 1989. 4. The least-square means of calving age on the milk yield were estimated 5,456.01kg in less than 24 months, 6,565.48kg in 61-66 months which were the highest least-square means. This effects were gradually increased until the 61-66months and gradually decreased after the 61-66months, with highly significant differences among different months of age at calving(p<0.01). 5. In the effects of farm, the least-square means of milk yield were estimated 4,959.50 kg in the lowest farm and 7,497.07kg in the highest farm. Among the milk yield of each farm the effects showed highly significant difference(p<0.01). 6. The least-square means of milk yield in the effects of lactation period were gradually increased with the lapse of the lactation period. Among the lactation period the effects showed highly significant difference(p<0.01).

• Journal of Radiation Protection and Research
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• v.14 no.1
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• pp.71-74
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• 1989

A statistical model for the relation between KARP membership and articles published in the KARP Journal on the yearly basis was obtained by using the least-squares method. From this, KARP membership potent to publish the KARP Journal up to 4 numbers a year were projected. It is revealed that at least 650 KARP members are needed.

• Journal of Astronomy and Space Sciences
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• v.18 no.2
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• pp.137-144
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• 2001

This paper presents the REA thrusters performance estimation results for the KOREASAT F1&F2 launched in 1995 The satellite tracking data obtained from the ground system from end of 1999 to beginning of the 2000 are used to estimate the thruster performance. The estimation algorithm is derived from the least square estimation theory and designed to estimate the velocity change induced by the on-boarded thruster firing as well as the orbit parameter. The estimation results show that the Koreasat F1 thruster are in bad thruster condition of 64% performance for REA when it fires in on-pulse mode. Here, the performance is defined by the ratio of the resulted velocity change to that of planned. But, in the case o( the Koreasat F2, it is found that the performance approximately reaches up to 100%, even after the 5 years of the mission.