• 대한원격탐사학회지
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• 제40권2호
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• pp.167-177
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• 2024

With advancements in satellite technology, interest in target detection and identification is increasing quantitatively and qualitatively. Synthetic Aperture Radar(SAR) images, which can be acquired regardless of weather conditions, have been applied to various areas combined with machine learning based detection algorithms. However, conventional studies primarily focused on the detection of stationary targets. In this study, we proposed a method to identify moving targets using an algorithm that integrates sub-aperture SAR images and cosine similarity calculations. Utilizing a transformer-based deep learning target detection model, we extracted the bounding box of each target, designated the area as a region of interest (ROI), estimated the similarity between sub-aperture SAR images, and determined movement based on a predefined similarity threshold. Through the proposed algorithm, the quantitative evaluation of target identification capability enhanced its accuracy compared to when training with the targets with two different classes. It signified the effectiveness of our approach in maintaining accuracy while reliably discerning whether a target is in motion.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(4)
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• pp.101-104
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• 2000

An efficient bit rate distribution technique that distributes available bits for multiple objects based on motion vector magnitude, size of object shape, and coding distortion is presented. This coding concept using the three parameters was exploited in MPEG-4 multiple object coding. But the scheme is likely to produce poor results such as allocating more bits to less important objects and degrading picture quality, due to the lack of analysis and research in view of human visual aspect. In this paper importance of each object is represented by the three parameters and visually analyzed. Target bits are distributed according to coding distortion using the pre-assigned shape and motion information.

• 한국정보통신학회논문지
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• 제4권5호
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• pp.1085-1093
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• 2000

이 논문에서는 객체의 크기, 움직임의 크기, 부호화 왜곡을 기준으로 다중객체간 가용비트를 효과적으로 분배하는 기법을 제안하였다. 세 변수를 이용하여 부호화하는 개념은 MPEG-4에서 다중객체를 부호화하는 데에 이용되었다. 그러나 변수들을 시각적인 관점에서 분석하여 이용하는 연구가 미흡하여 시각적으로 중요하지 않은 객체에 많은 비트가 할당되어 화질이 저하되는 결과를 초래하였다. 따라서 이 논문에서는 객체의 중요성을 세 가지 변수로 표현하고 시각적으로 비교하였다. 크기 및 움직임 정보는 입력 영상에서 미리 주어지고 왜곡량에 따라 비트를 분배하였다.

• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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• pp.1-13
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• 2006

The Lyapunov stability theory has been known inadequate to prove capturability of guidance laws because the equations of motion resulted from the guidance laws do not have the equilibrium point. By introducing a proper transformation of the range state, the original equations of motion for a stationary target can be converted into nonlinear equations with a specified equilibrium subspace. Physically, the equilibrium subspace denotes the direction of missile velocity to the target. By using a single Lyapunov function candidate, capturability of several PN laws for a stationary target is then proved for examples. In this approach, there is no assumption of the constant speed missile. The proposed method is expected to provide a unified and simplified scheme to prove the capturability of various kinds of guidance laws.

• 산업경영시스템학회지
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• 제35권4호
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• pp.24-32
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• 2012

Of many approaches to reduce motion analysis errors, the compensation method of anatomical landmarks estimates the position of anatomical landmarks during motion. The method models the position of anatomical landmarks with joint angle or skin marker displacement using the data of the so-called dynamic calibration in which anatomical landmark positions are calibrated in ad hoc motions. Then the anatomical landmark positions are calibrated in target motions using the model. This study applies the compensation methods with joint angle and skin marker displacement to three lower extremity motions (walking, sit-to-stand/stand-to-sit, and step up/down) in ten healthy males and compares their performance. To compare the performance of the methods, two sets of kinematic variables were calculated using different two marker clusters, and the difference was obtained. Results showed that the compensation method with skin marker displacement had less differences by 30~60% compared to without compensation. And, it had significantly less difference in some kinematic variables (7 of 18) by 25~40% compared to the compensation method with joint angle. This study supports that compensation with skin marker displacement reduced the motion analysis STA errors more reliably than with joint angle in lower extremity motion analysis.

• 한국전자파학회논문지
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• 제17권12호
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• pp.1249-1258
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• 2006

ISAR 자동 초점(autofocus) 기법이란 움직이는 표적에 대한 2차원 레이더 영상인 ISAR 영상을 얻을 때 표적에 의한 doppler-shift 때문에 발생하는 위상 오차를 예측, 제거하는 기법이다. 이러한 자동 초점 기법이 수행되지 않은 ISAR 영상은 위상 오차(phase ewer)에 의한 왜곡이 포함되기 때문에 초점이 맞지 않는 것처럼 흐린(blurred) 영상이 된다. 이러한 영상은 추후에 구분기(classifier)를 이용하여 표적 구분 시 올바른 구분을 보장할 수 없으므로 반드시 자동 초점 기법이 수행되어야 하며, 본 논문에서는 이를 위해 영상의 엔트로피(entropy)를 최소화시키는 알고리즘을 이용한다. ISAR 자동 초점 기법은 크게 range alignment 과정과 phase adjustment 과정으로 나뉘는데, range alignment 과정에서 샘플링 포인트(sampling point)의 수와 그에 따른 영상 품질과의 관계를 분석하고, phase adjustment 과정 을 수행하기 위한 알고리즘인 SSA(Stage-by-Stage Approaching)의 계산시간 단축을 위한 방법을 분석한다.

• The Journal of the Acoustical Society of Korea
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• 제17권3E호
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• pp.22-26
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• 1998

This paper proposes a simple method to measure system's performance in target tracking problems. Essentially employing the Cramer-Rao Lower Bound (CRLB) on tracking accuracy, an algorithm of predicting system's performance under various scenarios is developed. The input data is a collection of measurements over tim from sensors embedded in Gaussian noise. The target of interest may not maneuver over the processing time interval while the own ship observing platform may maneuver in an arbitrary fashion. The proposed approach is demonstrated and discussed through simulation results.

• International Journal of Contents
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• 제16권3호
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• pp.1-17
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• 2020

Human motion recognition is essential for user-centric services such as surveillance-based security, elderly condition monitoring, exercise tracking, daily calories expend analysis, etc. It is typically based on the movement data analysis such as the acceleration and angular velocity of a target user. The existing motion recognition studies are only intended to measure the basic information (e.g., user's stride, number of steps, speed) or to recognize single motion (e.g., sitting, running, walking). Thus, a new mechanism is required to identify the transition of single motions for assessing a user's consecutive motion more accurately as well as recognizing the user's body and surrounding situations arising from the motion. Thus, in this paper, we collect the human movement data through Android smartphones in real time for five targeting single motions and propose a mechanism to recognize a consecutive motion including transitions among various motions and an occurred situation, with the state transition model to check if a vulnerable (life-threatening) condition, especially for the elderly, has occurred or not. Through implementation and experiments, we demonstrate that the proposed mechanism recognizes a consecutive motion and a user's situation accurately and quickly. As a result of the recognition experiment about mix sequence likened to daily motion, the proposed adoptive weighting method showed 4% (Holding time=15 sec), 88% (30 sec), 6.5% (60 sec) improvements compared to static method.

• 한국군사과학기술학회지
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• 제8권2호
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• pp.49-57
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• 2005

The target localization using the line arrays buried in the seabed is a difficult problem due to the complex sea bottom characteristics and need to compensate the wave propagation effect to localize the target accurately Sound speed mismatch in the seabed causes a bias in the target bearing estimation and induces the localization error. In this paper we describe a target localization method with improved accuracy of target bearing and localization by calibration the sound speed in the seabed. The proposed algorithm is verified through the ocean data.

• 대한인간공학회지
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• 제29권6호
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• pp.915-924
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• 2010

Muscular strength in the elderly is important factors deciding on functional state in daily lives, and functional state shows a health condition. Resistance training to prevent loss of muscle mass and muscle fiber atrophy due to aging can increase muscle mass and strength. Recently, resistance training to improve muscular strength and endurance has been actively researched. Resistance training increases activities of daily living and ability of the elderly, which makes healthy senescent. ADL/IADL is suitable for measuring health condition of the elderly. In this study, target muscles of resistance training were chosen through a correlation analysis between ADLs and elementary motion, and we presented a procedure to select target muscles and exercise equipments. This procedure consist of a survey method that were described detailed motion of ADL/IADL. So we should be to extract resistance training machine to improve functions of regarding fundamental motion. Result of study may improve daily life activities of the elderly through objectives and scientific approaches. Furthermore, it will be helpful to studies about various fields of the elderly.