• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.625-628
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• 2007

We present an efficient and robust technique to estimate the velocity of moving targets from a single SAR image. In SAR images, azimuth image shift is a well known phenomenon, which is observed in moving targets having slant-range velocity. Most methods estimated the velocity of moving targets from the distance difference between the road and moving targets or between ship and the ship wake. However, the methods could not be always applied to moving targets because it is difficult to find the road and the ship wake. We adopted a method estimating the velocity of moving targets from azimuth differentials of range-compressed image. This method is based on an assumption that Doppler center frequency shift of moving target causes a phase difference in azimuth differential values. The phase difference is linearly distorted by Doppler rate due to the geometry of SAR image. The linear distortion is eliminated from phase removal procedure, and the constant phase difference is estimated. Finally, range velocity estimates for moving targets are retrieved. This technique is tested using an ENVISAT ASAR image in which several unknown ships are presented. The theoretical accuracy of this technique is discussed by SAR simulation. The advantages and disadvantages of this method over the conventional method are also discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권2호
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• pp.438-455
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• 2024

Recently, many unsupervised learning-based models have emerged for Just Noticeable Difference (JND) estimation, demonstrating remarkable improvements in accuracy. However, these models suffer from a significant drawback is that their heavy reliance on handcrafted priors for guidance. This restricts the information for estimating JND simply extracted from regions that are highly related to handcrafted priors, while information from the rest of the regions is disregarded, thus limiting the accuracy of JND estimation. To address such issue, on the one hand, we extract the information for estimating JND in an Adversarial Complementary Learning (ACoL) way and propose an ACoL-JND network to estimate the JND by comprehensively considering the handcrafted priors-related regions and non-related regions. On the other hand, to make the handcrafted priors richer, we take two additional priors that are highly related to JND modeling into account, i.e., Patterned Masking (PM) and Contrast Masking (CM). Experimental results demonstrate that our proposed model outperforms the existing JND models and achieves state-of-the-art performance in both subjective viewing tests and objective metrics assessments.

• East Asian mathematical journal
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• 제33권2호
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• pp.177-197
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• 2017

The purpose of this study is to investigate and analyze the understandings of elementary pre-service teachers about 'estimation' in the elementary mathematics. Together with this analysis, we identify elementary pre-service teacher's Mathematical Pedagogical Contents Knowledge(MPCK), especially focusing to Subject Matter Knowledge(SMK). In order to this goals, we investigate contents relating to 'estimation' from $1^{st}$ curriculum to 2009 revised curriculum and compare 'rounding up', 'rounding off', 'rounding' in the elementary mathematics textbooks. As results of investigations, 'estimation' has been teaching at the 'Measurement' domain from $3^{rd}$ curriculum, but contexts of measuring weaken from $7^{th}$ curriculum. 'Rounding up(off)' is defined three types in the textbooks from $1^{st}$ to 2009 revised curriculum. And we examine elementary pre-service teachers through the questions on these 'estimation' contents. On the analysis of pre-service teacher's understanding relating MPCK, four themes is summarized as followings; the understanding of '0' in the 'rounding up', the cognitive gap between 'rounding up' and 'rounding off', the difference of percentage of correct answers according to types of question in the 'rounding up', and the difference between the definition of 'rounding up' and the definition of 'rounding'.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 추계학술대회
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• pp.70-72
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• 2019

For the safe and reliable operation of Lithium-ion batteries in Electric Vehicles (EVs) or Energy Storage Systems (ESSs), it is essential to have accurate information of the battery such as State of Charge (SOC). Many kinds of different techniques to estimate the SOC of the batteries have been developed so far such as the Kalman Filter. However, when it is applied to the multiple number of batteries it is difficult to maintain the accuracy of the estimation over all cells due to the difference in parameter value of each cell. Moreover the difference in the parameter of each cell may become larger as the operation time accumulates due to aging. In this paper a novel Deep Neural Network (DNN) based SOC estimation method for multi cell application is proposed. In the proposed method DNN is implemented to learn non-linear relationship of the voltage and current of the lithium-ion battery at different SOCs and different temperatures. In the training the voltage and current data of the Lithium battery at charge and discharge cycles obtained at different temperatures are used. After the comprehensive training with the data obtained with a cell resulting estimation algorithm is applied to the other cells. The experimental results show that the Mean Absolute Error (MAE) of the estimation is 0.56% at 25℃, and 3.16% at 60℃ with the proposed SOC estimation algorithm.

• 한국정보과학회논문지:소프트웨어및응용
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• 제31권2호
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• pp.173-181
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• 2004

본 논문에서는 움직이는 카메라로부터 획득한 연속영상에서 이동물체를 자동으로 검출하고 추적하는 시스템을 제안한다. 제안된 방법은 크게 이동물체 검출과 추적과정으로 나뉘어진다. 이동물체는 BBME(block-based motion estimation)와 DD(double difference)를 통합한 방법을 이용하여 검출된다. 검출된 이동물체는 히스토그램 백 프로젝션을 통하여 분할되며, 히스토그램 인터섹션과 XY-프로젝션을 사용하여 대상물체를 정합하고 추적된다. 본 논문에서는 컴퓨터 모의실험을 통하여 제안된 방법이 움직이는 카메라로부터 획득된 영상에서 이동물체를 검출하고 큰 오차 없이 추적함을 보였다.

• Journal of Magnetics
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• 제19권2호
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• pp.174-180
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• 2014

In this paper, a new and simple method is proposed to quickly estimate the induced electric field in the human child exposed to a 100 kHz-10 MHz magnetic field, for the sake of electromagnetic field (EMF) safety assessment. The quasi-static finite-difference time-domain (FDTD) method is used to calculate the induced electric fields in high resolution 3D human child models with various body size parameters, in order to derive the correction factor for the estimation equation. The calculations are repeated for various frequencies and incident angles of the magnetic field. Based on these calculation results, a new and simple estimation equation for the 99th percentile value of the body electric field is derived that depends on the body size parameters, and the incident magnetic field. The estimation errors were equal to or less than 5.1%, for all cases considered.

• 대한원격탐사학회지
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• 제23권5호
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• pp.421-430
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• 2007

This paper presents the results of the ocean surface current velocity estimation using 6 Radarsat-1 SAR images acquired in west coastal area near Incheon. We extracted the surface velocity from SAR images based on the Doppler shift approach in which the azimuth frequency shift is related to the motion of surface target in the radar direction. The Doppler shift was measured by the difference between the Doppler centroid estimated in the range-compressed, azimuth-frequency domain and the nominal Doppler centroid used during the SAR focusing process. The extracted SAR current velocities were statistically compared with the current velocities from the high frequency(HF) radar in terms of averages, standard deviations, and root mean square errors. The problem of the unreliable nominal Doppler centroid for the estimation of the SAR current velocity was corrected by subtracting the difference of averages between SAR and HF-radar current velocities from the SAR current velocity. The corrected SAR current velocity inherits the average of HF-radar data while maintaining high-resolution nature of the original SAR data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1472-1474
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• 2001

In this paper, a method was presented to estimate the contamination degree of outdoor insulator by the measurement of surface leakage current. Contamination is one of the most important factor to determine the performance of insulator. Thus, it is very important to exam the contamination degree on the outdoor insulator. There are many limits, such as reliability of data, interval of measurement and similarity of environmental conditions, in conventional method. So, the estimation technique for contamination has been needed to monitor the accurate pollution degree of insulator in situ. In this investigation, phase difference was measured to compare the variance of phase difference with the contamination degree and relative humidity. From the result, we could confirm the capability of the estimation method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.851-854
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• 2003

The low power motion estimation for MPEG-4 is a soft-core for hardwired motion estimation block in MPEG-4. This motion estimation is modified by 10 difference mode. So, this motion estimation decrease a power consumption compare conventional step search. This modified 4SS Low power Motion Estimation has been tested and verified to be valid for implementation of FPGA. The average PSNR between the original image and the motion-compensated image is 28.25dB. And Power consumption is 26mW.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.76-81
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• 2021

This study proposes a method to reduce the phase error of the received signal to detect the object bearing. The phase shift of the received signal occurs due to the multipath of the signal by natural structure or artificial structures. When detecting the direction of the object using radio waves, the phase of the received signal cannot be accurately detected because of the phase bearing error in the object detection direction. The object detection direction estimation depends on the phase difference, antenna installation distance, signal source wavelength, frequency band and bearing angle. This study reduces the error of the phase bearing by using the phase delay of the relative phase difference for the signals incident on the two antennas. Through simulation, we analyzed the object direction detection performance of the proposed method and the existing method. Three targets are detected from the [-15°, 0°, 15°] direction. The existing method detects the target at [-13°, 3°, 17°], and the proposed method detects the at [-15°, 0°, 15°]. As a result of the simulation, the target detection direction of the proposed method is improved by 2 degrees compared to the existing method.