• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2359-2364
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• 2017

This paper proposes a scale factor based range estimation method using a sum of squares (SOS) method. Many previous studies measured distance by using a camera, which usually required two cameras and a long computation time for image processing. To overcome these disadvantages, we propose a range estimation method for an object using a single moving camera. A SOS-based Luenberger observer is proposed to estimate the range on the basis of the Euclidean geometry of the object. By using a scale factor, the proposed method can realize a faster operation speed compared with the previous methods. The validity of the proposed method is verified through simulation results.

• 한국전자통신학회논문지
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• 제5권4호
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• pp.372-378
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• 2010

시 공간적으로 인접한 주변 블록들의 움직임 정보들을 이용하여 적응적으로 탐색 범위를 조절하는 고속 움직임 추정 기법을 제안한다. 기존의 탐색 범위 조절을 통한 고속 움직임 추정 기법들은 참조 프레임에 있는 모든 블록들의 움직임 벡터들 중에서 최댓값을 이용하여 현재 블록의 탐색 범위 조절을 하기 때문에 움직임이 작은 블록들에 대해서는 최적의 탐색 범위 조절을 못할 수 있다. 본 논문에서는 참조 프레임과 현재 프레임에서 현재 블록과 인접한 주변 블록들의 움직임 정보를 동시에 고려하여 최적의 탐색 범위를 결정하여 움직임 추정을 고속으로 할 수 있는 움직임 추정 기법을 제안한다. 시간적으로 인접된 블록들 즉 참조 프레임에 있는 주변 블록들의 움직임 정보를 이용하면 움직임이 작은 블록의 탐색 범위의 크기를 적절하게 작게 할 수 있어 고속의 움직임 추정을 할 수 있다. 실험을 통하여 본 논문에서 제안한 시 공간적 주변 블록들의 움직임 정보를 이용하는 탐색 범위 조절을 통한 고속 움직임 추정 기법이 비트율과 움직임 추정 오차는 거의 비슷하게 유지하면서 기존의 방법인 Simple Dynamic Search Range(SDSR) 기법보다 탐색 점의 수를 약 15% 더 감소시킬 수 있음을 확인하였다.

• ETRI Journal
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• 제43권1호
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• pp.120-132
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• 2021

A frequency diverse array (FDA) multiple-input multiple-output (MIMO) radar employs a small frequency increment across transmit elements to produce an angle-range-dependent beampattern for target angle and range detection. The joint angle and range estimation problem is a trilinear model. The traditional trilinear alternating least square (TALS) algorithm involves high computational load due to excessive iterations. We propose a fast-convergence trilinear decomposition (FC-TD) algorithm to jointly estimate FDA-MIMO radar target angle and range. We first use a propagator method to obtain coarse angle and range estimates in the data domain. Next, the coarse estimates are used as initialized parameters instead of the traditional TALS algorithm random initialization to reduce iterations and accelerate convergence. Finally, fine angle and range estimates are derived and automatically paired. Compared to the traditional TALS algorithm, the proposed FC-TD algorithm has lower computational complexity with no estimation performance degradation. Moreover, Cramer-Rao bounds are presented and simulation results are provided to validate the proposed FC-TD algorithm effectiveness.

• 한국군사과학기술학회지
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• 제11권4호
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• pp.116-123
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• 2008

In this paper we study the performance of the measurement time-delay estimation of tightly-coupled GPS/INS(Global positioning system/Inertial Navigation system) system. Generally, the heading error estimation performance of loosely-coupled GPS/INS system using GPS's Navigation Solution is poor. In the case of tightly-coupled GPS/INS system using pseudo-range and pseudo-range rate, the heading error estimation performance is better. However, the time-delay error on the measurement(pseudo-range rate) make the heading error estimation performance degraded. So that, we propose the time-delay model on the measurement and compose the time-delay estimator. And we confirm that the heading error estimation performance in the case of measurement time-delay existence is similar with the case of no-delay by Monte-Carlo simulation.

• 한국군사과학기술학회지
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• 제13권3호
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• pp.413-420
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• 2010

An Estimation of VHF data link range for EW(Electronic Warfare) equipment in the sea environment was studied to predict the data link range between transmitting and receiving station. The theoretical estimation predicts within 3% error with actual measurement of VHF data link range at sea. Data link range factors including refraction and reflection are added in the basic wave propagation equation. The effect of refraction and reflection to the range is analysed with quantity level.

• 전기전자학회논문지
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• 제22권3호
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• pp.599-604
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• 2018

계단 주파수 레이더는 송신 펄스의 주파수를 일정한 간격으로 증가시켜 넓은 합성 대역폭을 생성함으로써 고해상도 거리추정을 구현하는 방식이다. 그러나 이동표적의 경우에는 거리-도플러 결합 현상으로 인해 정확한 거리 추정이 어렵게 된다. 본 논문에서는 초기에 코히어런트 펄스열을 갖는 계단 주파수 레이더 파형을 이용하여 이동표적의 속도를 추정하고, 거리-도플러 결합 현상을 보상함으로써 얻어지는 고해상도 거리 추정 과정을 분석하고, 시뮬레이션을 통해 이를 검증하였다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2020년도 추계학술대회
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• pp.252-255
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• 2020

Unsupervised deep learning methods have shown impressive results for the challenging monocular depth estimation task, a field of study that has gained attention in recent years. A common approach for this task is to train a deep convolutional neural network (DCNN) via an image synthesis sub-task, where additional views are utilized during training to minimize a photometric reconstruction error. Previous unsupervised depth estimation networks are trained within a fixed depth estimation range, irrespective of its possible range for a given image, leading to suboptimal estimates. To overcome this suboptimal limitation, we first propose an unsupervised adaptive depth estimation method guided by minimum and maximum (min-max) depth priors for a given input image. The incorporation of min-max depth priors can drastically reduce the depth estimation complexity and produce depth estimates with higher accuracy. Moreover, we propose a novel network architecture for adaptive depth estimation, called the AdaMM-DepthNet, which adopts the min-max depth estimation in its front side. Intensive experimental results demonstrate that the adaptive depth estimation can significantly boost up the accuracy with a fewer number of parameters over the conventional approaches with a fixed minimum and maximum depth range.

• 전기전자학회논문지
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• 제22권2호
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• pp.309-315
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• 2018

계단 주파수 레이더(Stepped Frequency Radar: SFR)는 송신 펄스의 주파수를 점진적으로 증가시켜 넓은 합성 대역폭을 만듦으로써 높은 거리 해상도를 얻는 방식이다. 그런데 이동표적의 경우 거리-도플러 결합(range-Doppler coupling) 현상으로 정확한 거리 추정을 할 수 없게 되므로 정확한 속도 추정을 통한 보상이 필요하다. 본 논문에서는 코히어런트 펄스열(Coherent Pulse Train: CPT)을 갖는 계단 주파수 레이더 파형을 제안하고, 이를 이용한 속도 추정 및 파라미터에 따른 결과를 기존의 VMD(Velocity Measurement Data) 방식과 시뮬레이션을 통해 비교하고 분석하였다.

• Communications for Statistical Applications and Methods
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• 제31권3호
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• pp.337-347
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• 2024

Kernel density estimation is a prevalent technique employed for nonparametric density estimation, enabling direct estimation from the data itself. This estimation involves two crucial elements: selection of the kernel function and the determination of the appropriate bandwidth. The selection of the bandwidth plays an important role in kernel density estimation, which has been developed over the past decade. A range of methods is available for selecting the bandwidth, including the plug-in bandwidth. In this article, the proposed plug-in bandwidth is introduced, which leverages shifted Chebyshev series-based approximation to determine the optimal bandwidth. Through a simulation study, the performance of the suggested bandwidth is analyzed to reveal its favorable performance across a wide range of distributions and sample sizes compared to alternative bandwidths. The proposed bandwidth is also applied for kernel density estimation on real dataset. The outcomes obtained from the proposed bandwidth indicate a favorable selection. Hence, this article serves as motivation to explore additional plug-in bandwidths that rely on function approximations utilizing alternative series expansions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1822-1825
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• 2003

A practical range estimator based on the robust Kalman filter is proposed to solve the range estimation problem for surface to air missile(SAM) homing guidance. Apart from the previous works based on the extended Kalman filter(EKF) with bearing only measurement, the proposed scheme makes use of line-of-sight(LOS) rate to ensure the fast convergency at long-range. In this reason, the robust Kalman filter is considered to deal with LOS rate measurement error. The recursive linear structure of proposed filter is easy to implement and make it possible to reduce computational burdens. Moreover, it shows good estimation performance without specific guidance law such as oscillation proportional navigation guidance(OPNG).