• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.299-302
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• 2006

본 연구에서는 화학적으로 활성화된 에너지 물질의 경계면을 정확하게 추적하는 기법을 소해한다. 이러한 경계면 추적기법은 Level Set기반의 Ghost Fluid Concept을 이용하여 폭발과 같은 화학적 현상을 포함하는 에너지 물질의 경계면을 정확하게 파악하고, 쉽게 multi material, phase등과 같은 현상으로 확장이 가능하다. 본 연구에서는 이러한 multi physics modeling을 위한 선행연구로써 basic sharp interface tracking, impact problem에 대해서 소개할 것이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.41.3-41
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• 2002

Motion estimation using Full-Search(FS) and Block-Matching Algorithm(BMA) is often used in the case of moving object tracking by vision sensors. However these methods often miss the real-time vision data because these schemes suffer the heavy computational load. When the image size of moving object is changed in an image frame according to the distance between the camera of mobile robot and the moving object, the tracking performance of a moving object may decline with these methods because of the shortage of active handling. In this paper, the variable-representative block that can reduce a lot of data computations, is defined and optimized by changing the size of representative block accor...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.13-16
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• 1999

An active contour model, Snake, was developed as a useful segmenting and tracking tool lot rigid or non-rigid (i.e. deformable) objects by Kass in 1987 In this research, Snake is newly designed to cover this large moving case. Image flow energy is proposed to give Snake the motion information of the target object. By this image flow energy Snake's nodes can move uniformly along the direction of the target motion in spite of the existences of local minima. Furthermore, when the motion is too large to apply image flow energy to tracking, a jump mode is proposed for solving the problem. The vector used to make Snake's nodes jump to the new location can be obtained by processing the image flow. The effectiveness of the proposed Snake is confirmed by some simulations.

• Journal of electromagnetic engineering and science
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• 제1권2호
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• pp.131-138
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• 2001

The DTV (Digital TV) tuner for an 8-VSB (Vestigial Side-Band) modulation was developed to meet the requirements of the ATSC (Advanced Television Systems Committee). The double frequency conversion and the active tracking filter in the front-end were used to cancel interferences between adjacent channels and multi-channels by suppressing the IF beat and the Image frequency. However, It was impossible to get frequency mapping between the tracking filter and the first VCO (Voltage Controlled Oscillator) in the existing DTV tuner structure which differs from the NTSC (National Television Systems Committee) tuner. This paper, therefore, suggests an assailable structure and a new method for the automatic frequency selection by mapping the frequency characteristics over the tracking voltage and the combined HW which is composed of a Micro-controller, an EEPROM (Electrically Erasable Programmable Read Only Memory), a DAC (Digital-to-Analog Converter), an OP amplifier, and a switch driver.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1831-1839
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• 2003

This paper deals with design and control of passive multiple trailer systems fer practical applications. Due to cost and complexity of trailer mechanism, passive systems are preferred to active systems in this research. The control objective is to minimize trajectory tracking errors of passive multiple trailers. Three types of passive trailer systems-direct-hooked, three-point, and off-hooked- are discussed in this paper. Trajectory tracking performance and stability issues under constant velocity motion are carried out for three types. Various simulations and experiments have been also performed for these three types. It is shown that the proposed off-hooked trailer system produces better tracking performance than the other types.

• Journal of Information Processing Systems
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• 제17권4호
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• pp.772-786
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• 2021

The process of tracking suspicious behavior manually on a system and gathering evidence are labor-intensive, variable, and experience-dependent. The system logs are the most important sources for evidences in this process. However, in the Microsoft Windows operating system, the action events are irregular and the log structure is difficult to audit. In this paper, we propose a model that overcomes these problems and efficiently analyzes Microsoft Windows logs. The proposed model extracts lists of both common and key events from the Microsoft Windows logs to determine detailed actions. In addition, we show an approach based on the proposed model applied to track illegal file access. The proposed approach employs three-step tracking templates using Elastic Stack as well as key-event, common-event lists and identify event lists, which enables visualization of the data for analysis. Using the three-step model, analysts can adjust the depth of their analysis.

• 한국항공우주학회지
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• 제43권10호
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• pp.902-909
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• 2015

본 논문에서는 인공위성 근접운용을 위한 단일 영상 기반 상대항법에 대한 연구를 수행하였다. 추적 위성은 하나의 카메라 센서만을 이용하여 표적 위성을 관측하고 영상추적을 통해 표적 위성의 위치 정보를 얻게 된다. 그러나 단일 영상만을 이용할 경우, 표적과의 상대 거리에 해당하는 깊이 정보를 얻기 힘들다. 이러한 문제를 해결하기 위해 능동 윤곽 기법을 영상 추적에 적용하였다. 능동 윤곽 기법을 통해 표적의 이미지 크기를 얻을 수 있고 이러한 형상 정보를 바탕으로 상대 거리를 간접적으로 계산할 수 있다. 두 인공 위성이 상대 운동을 하는 우주환경을 구현하고 가상의 카메라 영상을 생성하기 위해 3차원 가상현실이 이용되었다. 추적 위성은 UKF를 이용하여 표적 위성에 대한 상대위치를 추정하면서 글라이드슬로프 접근 기법을 이용하여 표적 위성에 근접한다. 상대항법의 성능을 분석하기 위해서 폐 루프 시뮬레이션을 수행하였다.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2006년도 학술대회 1부
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• pp.1044-1049
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• 2006

얼굴 추적은 Vision base HCI의 핵심인 얼굴인식, 표정인식 그리고 Gesture recognition등의 다른 여러 기술을 지원하는 중요한 기술이다. 이런 얼굴 추적기술에는 영상(Image)의 Color또는 Contour등의 불변하는 특징들을 사용 하거나 템플릿(template)또는 형태(appearance)를 사용하는 방법 등이 있는데 이런 방법들은 조명환경이나 주위 배경등의 외부 환경에 민감하게 반응함으로 해서 다양한 환경에 사용할 수 없을 뿐더러 얼굴영상만을 정확하게 추출하기도 쉽지 않은 실정이다. 이에 본 논문에서는 deformable한 model을 사용하여 model과 유사한 shape과 appearance를 찾아 내는 AAM(Active Appearance Model)을 사용하는 얼굴 추적 시스템을 제안하고자 한다. 제안된 시스템에는 기존의 Combined AAM이 아닌 Independent AAM을 사용하였고 또한 Fitting Algorithm에 Inverse Compositional Image Alignment를 사용하여 Fitting 속도를 향상 시켰다. AAM Model을 만들기 위한 Train set은 150장의 4가지 형태에 얼굴을 담고 있는 Gray-scale 영상을 사용 하였다. Shape Model은 각 영상마다 직접 표기한 47개의 Vertex를 Trianglize함으로서 생성되는 71개의 Triangles을 하나의 Mesh로 구성하여 생성 하였고, Appearance Model은 Shape 안쪽의 모든 픽셀을 사용해서 생성하였다. 시스템의 성능 평가는 Fitting후 Shape 좌표의 정확도를 측정 함으로서 평가 하였다.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.509-516
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• 2012

This paper describes the testing and experimental characterization of a linear permanent magnet actuator, which is designed and developed for active vehicle suspension, under both static and dynamic conditions. Since the active suspension unit operates over a wide force-velocity range with varying duty ratios, it is essential to establish an effective thermal model which can be used for assessing temperature rise of the actuator under various operating conditions. The temperature rise of the actuator is measured and the results are compared with the prediction by the derived transient thermal model. It is shown that the measured actuator parameters and characteristics are closed to their predicted values. The linear actuator is controlled by a dSPACE system via a three phase inverter and its velocity tracking performance is presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.295-299
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• 1996

When the current of a power converter is controlled with a digital controller, it generally shows the error due to execution time delay. The error may be considerable in such systems as active power filters wherein the current varies steeply even in steady state, as well as in transients. Therefore, it is of particular importance to compensate the time delay effect in a digitally-controlled active power filter. This paper introduces a modification of so-called predictive current control, by taking the control time delay into consideration. The results of simulation and experiment with a 10 kVA active power filter prototype show considerable improvement in current tracking capability, validating the proposed current control method.