• 한국항해항만학회지
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• 제37권5호
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• pp.447-452
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• 2013

해상교통관제시스템(VTS)은 선박의 위치, 속도, 침로 등 해상 교통 정보를 획득하기 위하여 다수의 해상감시레이더를 주요 센서로 이용하고 있으며, 거리 및 방위각 바이어스와 같은 2차원 해상감시레이더의 시스템 오차는 레이더 영상 및 표적 추적정보의 정확도를 크게 저하시킬 수 있다. 따라서 해상교통관제시스템에서 정확한 표적정보를 제공하기 위하여 레이더의 시스템 오차는 정밀하게 보정되어야 한다. 본 논문에서는 VTS 관제영역에 설치된 항로표지의 위치정보를 이용하여 2차원 해상감시레이더의 거리 및 방위각 오차를 보정하기 위한 방법을 제안한다. 2차원 레이더 측정값의 표준오차 모델과 항로표지 위치정보로부터 측정 잔차 모델을 유도하고, 레이더 시스템 오차를 추정하기 위한 선형 칼만필터를 설계한다. Monte-Carlo 모의실험을 통하여 제안한 방법을 검증하고, 항로표지 정보의 개수에 따른 레이더 시스템 오차 추정의 수렴 특성 및 정확도를 분석한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1325-1328
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• 2007

When we visualize the sound field radiated from a spherical sound source, spherical acoustic holography is proper among acoustic holography methods. However, there are measurement errors due to sensor position mismatch, sensor mismatch, directivity of sensor, and background noise. These errors are amplified if one predicts the pressures close to the sources: backward prediction. The goal of this paper is to quantitatively examine the effects of the error due to sensor position mismatch on acoustic pressure estimation. This paper deals with the cases of which the measurement deviations are distributed irregularly on the hologram plane. In such cases, one can assume that the measurement is a sample of many measurement events, and the cause of the measurement error is white noise on the hologram plane. Then the bias and random error are derived mathematically. In the results, it is found that the random error is important in the backward prediction. The relationship between the random error amplification ratio and the measurement parameters is derived quantitatively in terms of their energies.

• Journal of Astronomy and Space Sciences
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• 제29권3호
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• pp.295-303
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• 2012

In this study, we compared the precipitable water vapor (PWV) data derived from the radiosonde observation data at Sokcho Observatory and the PWV data at Sokcho Global Positioning System (GPS) Observatory provided by Korea Astronomy and Space Science Institute, for the years of 2006, 2008, 2010, and analyzed the radiosonde seasonal, diurnal bias according to radiosonde sensor types. In the scatter diagram of the daytime and nighttime radiosonde PWV data and the GPS PWV data, dry bias was found in the daytime radiosonde observation as known in the previous study. Overall, the tendency that the wet bias of the radiosonde PWV increased as the GPS PWV decreased and the dry bias of the radiosonde PWV increased as the GPS PWV increased. The quantitative analysis of the bias and error of the radiosonde PWV data showed that the mean bias decreased in the nighttime except for 2006 winter, and in comparison for summer, RS92-SGP sensor showed the highest quality.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.344-351
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• 2017

This paper presents a method to estimate steady wind and airspeed bias error using an aircraft with GPS and airspeed sensor. The estimation uses the vector relation between the inertial, air, and wind velocities through a novel design of an extended Kalman filter. The observability analysis is also presented to show that the aircraft is required to keep changing its flight direction for the desired observability. The feasibility and performance of the proposed algorithm is demonstrated through simulations and flight experiments.

• Journal of the Korean Statistical Society
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• 제25권4호
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• pp.557-566
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• 1996

The aim of this paper is to find a suitable design which minimizes the expected discrepancy: in fitting a first order model fearing quadratic terms as bias where there are more than two correlated responses. Kim and Draper(1994) discussed about choosing a design for straight line fits to two correlated responses The general case with r responses is examined here and the result is applied to a specific case to help understandings.

• Communications for Statistical Applications and Methods
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• 제4권1호
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• pp.177-183
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• 1997

A data-adaptive order selection procedure is proposed for local polynomial nonparametric regression. For each given polynomial order, bias and variance are estimated and the adaptive polynomial order that has the smallest estimated mean squared error is selected locally at each location point. To estimate mean squared error, empirical bias estimate of Ruppert (1995) and local polynomial variance estimate of Ruppert, Wand, Wand, Holst and Hossjer (1995) are used. Since the proposed method does not require fitting polynomial model of order higher than the model order, it is simpler than the order selection method proposed by Fan and Gijbels (1995b).

• Journal of the Korean Data and Information Science Society
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• 제26권2호
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• pp.535-545
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• 2015

In a various range of applications including hydrology, the type-I extreme value distribution has been extensively used as a probabilistic model for analyzing extreme events. In this paper, we introduce methods for estimating the scale parameter of the type-I extreme value distribution. A simulation study is performed to compare the estimators in terms of mean-squared error and bias, and the obtained results are provided.

• 한국통신학회논문지
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• 제29권2C호
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• pp.298-305
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• 2004

본 논문은 워드길이가 W 비트인 입력으로부터 W 비트를 출력하는 고정길이 modified Booth 곱셈기에 대한 오차보상 방법을 설명한다. 효율적으로 양자화 오차를 보상하기 위해 Booth 인코더의 출력정보를 이용하여 오차보상 바이어스를 생성한다. 절단된 부분이 양자화 오차에 미치는 영향에 따라 두 그룹(major or minor group)으로 나누고, 각 그룹에 서로 다른 오차보상 방법을 적용한다. 기존 방법과 비교하여 제안한 방법이 오차보상 바이어스를 생성하는 회로의 하드웨어 오버헤드는 비슷하면서 약 50％ 정도 양자화 오차가 적음을 시뮬레이션을 통해 보인다. 또한, 면적과 전력소모 면에서 제안한 고정길이 곱셈기가 이상적인 곱셈기 보다 약 40％ 정도 적게 나타났다.

• 한국항공우주학회지
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• 제35권8호
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• pp.741-746
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• 2007

본 논문에서는 공대지 무장의 무장투하정확도에 대한 해석기법을 제시하였다. 항공기의 전투효과도(Combat Effectiveness)를 평가하는데 있어 중요한 요인인 공격능력(Lethality)은 공대지 무장투하정확도 개선능력에 좌우된다. 항공기 초기 설계단계부터 최종 검증단계 까지 무장투하정확도에 영향을 미치는 요소들을 기술하였으며 각 요소들을 무장투하정확도에 반영하는 기법과 정량적으로 평가하는 방안을 제시하였다. 무장투하정확도 분석은 Bias error를 영으로 가정하고 Random error에 의한 투하오차만을 분석 대상으로 하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.888-893
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• 2005

Since inertial sensor errors which increase with time are caused by initial orientation error and sensor errors(accelerometer bias and gyro drift bias), the accuracy of these devices, while still improving, is not adequate for many of today's high-precision, long-duration sea, aircraft, and long-range flight missions. This paper presents a navigation error compensation scheme for Strap-Down Inertial Navigation System(SDINS) using star tracker. To be specific, SDINS error model and measurement equation are derived, and Kalman filter is implemented. Simulation results show the boundedness of position and attitude errors.