• Journal of Aerospace System Engineering
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• 제16권6호
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• pp.24-34
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• 2022

This paper investigates the capture of a 12U-sized CubeSat space object using a spider-web structure-based space net. The structural dynamics analysis program ABAQUS is used to simulate the shock-absorbing capability of the space net with a diagonal length of 2.828 m. The space object is modelled as a rigid body, and the space net is modelled using non-linear elastic beam elements. The simulations reveal that the spider-web structure-based space net outperforms the squared space net of the same structural weight in capturing the space object. The numerical simulations are conducted to examine the successful or unsuccessful captures of the space object in various cooperative and non-cooperative motions.

• Journal of the Institute of Electronics Engineers of Korea SC
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• 제47권6호
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• pp.86-96
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• 2010

In this paper, we propose stereo vision-based obstacle detection and vehicle verification methods using U-disparity map and bird's-eye view mapping. First, we extract a road feature using maximum frequent values in each row and column. And we extract obstacle areas on the road using the extracted road feature. To extract obstacle areas exactly we utilize U-disparity map. We can extract obstacle areas exactly on the U-disparity map using threshold value which consists of disparity value and camera parameter. But there are still multiple obstacles in the extracted obstacle areas. Thus, we perform another processing, namely segmentation. We convert the extracted obstacle areas into a bird's-eye view using camera modeling and parameters. We can segment obstacle areas on the bird's-eye view robustly because obstacles are represented on it according to ranges. Finally, we verify the obstacles whether those are vehicles or not using various vehicle features, namely road contacting, constant horizontal length, aspect ratio and texture information. We conduct experiments to prove the performance of our proposed algorithms in real traffic situations.

• Journal of the Korean Institute of Telematics and Electronics
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• 제11권1호
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• pp.40-46
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• 1974

This paper deals with the self-excited mixer using tunnel diode oscillator operated as a microwave source and Doppler signal detector. The system impedance, the oscillation condition and the frequency conversion theory including moving target are investigated. The oscillating frequency and the output of tunnel diode oscillator are 2.035 GHz and 0.1 mW. The input signal frequency which is equivalent to Doppler signal is lower than tunnel diode oscillator frequency by 125 MHz. TDe conversion loss has been investigated as a functicn of input signal level. This loss is greater than 67 db for the large pump mode.

• Journal of Biomedical Engineering Research
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• 제20권2호
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• pp.165-172
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• 1999

An enhancement technique for phase dependent image contrast in MRI(Manetic Resonance Imaging) is proposed. Because the method can enhance inherent phase contrast it is suited for susceptibility imaging and flow imaging where intravoxel phase is a source of image contrast. In this paper, applying external phase in the voxel enhances phase contrast. The external phase is generated by a tailored RF pulse so that one can control the phase contrast and even produces phase only contrast. Signal intensity due to both inherent phase and external phase is analyzed and the proposed technique is applied to a susceptibility effect only imaging and a flow effect only imaging. To verify the proposed technique, computer simulations are performed and their results are given.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.721-724
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• 2014

Ultrasonic sensor is used widely for many applications because low cost, simple structure, and low restriction. There are many difficulties to recognize an object by use an ultrasonic sensor, because of low resolution, poor direction, and measurement error. To improve the these problem, we use the various kinds of sensor arrangement methods, large amount of sensor, and change the arrangement pattern of sensor. In this paper, to obtain the most basic parameters for pattern recognition such as distance, dimension of the object, an angle of the object, we get the improved results by use the intelligent calculation algorithm based on Neuro-Fuzzy. This method use the multifarious output voltage of ultrasonic sensor by simple electronic circuit.

• Proceedings of the Korea Multimedia Society Conference
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• 한국멀티미디어학회 2002년도 추계학술발표논문집
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• pp.339-342
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• 2002

동화상 압축에서 사용되는 움직임 벡터는 영상을 일정한 크기의 블록으로 나누어 이전 영상과 가장 예측 오류가 적은 곳을 지정하여 예측한다. 블록의 이동 정도는 수직. 수평의 선형적인 움직임(translational displacements)을 가정하여 사용하기 때문에 실제 화상에서 자주 나타나는 물체의 확대 또는 축소에 의한 크기 변화. 회전. 일그러짐 등의 변화에 올바르게 예측하지 못하는 문제를 가지고 있다. 본 논문은 블록의 선형적인 이동은 물론이고 4개 노드를 자유롭게 움직임일 수 있는 왜곡된 블록 정합 방식의 움직임 예측 기법에 대하여 소개하고 왜곡 블록 정합 방식에서 나타날 수 있는 기하학적인 오류를 수정하는 보정 방법에 관해 논의한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2017년도 추계학술대회
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• pp.88-90
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• 2017

현재 한국해양과학기술원에서는 선박비행체 탑재용 복합센서를 개발 및 시험 적용 중에 있다. 그러나 얻어진 영상 데이터를 통해서는 목표물에 대한 정확한 위치 정보를 파악할 수 없다. 또한 크기가 큰 물체도 거리가 멀면 영상에선 작아 보이기 때문에 목표물의 크기 또한 파악하기 힘들다. 이를 보완하기 위해 본 연구에서는 복합센서를 통해 획득한 영상에 대해 warping 및 기하보정, 선박 및 익수자 자동 탐지 알고리듬, 위치 및 계수 정보 산출에 대해 소개한다. 또한 실제 실험을 통해 해당 알고리듬을 검증하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 한국컴퓨터정보학회 2018년도 제57차 동계학술대회논문집 26권1호
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• pp.163-164
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• 2018

최근 생물학 등 여러 학문이 결합한 바이오닉스 기술을 이용하여 시력을 회복시키려는 인공 시각 전달 장치의 개발이 시도되고 있다. 본 논문에서는 인간의 물체 지각의 특성인 자기유사성에 적합한 영상 압축 기법에 대하여 조사하여 영상인식을 위한 최적의 학습 데이타 구성에 대하여 제안하고자 한다. 실험결과, 레인지 블록 크기에 따라 인식율의 변화는 나타나지만 레인지 크기가 작아질수록 별 차이가 없음을 알 수 있었다.

• Journal of Broadcast Engineering
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• 제7권2호
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• pp.181-191
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• 2002

Video based surveillance systems based on an active camera require a fast algorithm for real time detection and tracking of local motion in the presence of global motion. This paper presents a new fast and efficient motion detection and tracking algorithm using the displaced frame difference (DFD). In the Proposed algorithm, first, a Previous frame is adaptively selected according to the magnitude of object motion, and the global motion is estimated by using only a few confident matching blocks for a fast and accurate result. Then, a DFD is obtained between the current frame and the selected previous frame displaced by the global motion. Finally, a moving object is extracted from the noisy DFD by utilizing the correlation between the DFD and current frame. We implement this algorithm into an active camera system including a pan-tilt unit and a standard PC equipped with an AMD 800MHz processor. The system can perform the exhaustive search for a search range of 120, and achieve the processing speed of about 50 frames/sec for video sequences of 320$\times$240. Thereby, it provides satisfactory tracking results.

• Journal of the Korea Computer Graphics Society
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• 제13권3호
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• pp.19-24
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• 2007

In this paper, we describe a method of defining an object's real length in order to compare objects' lengths precisely using all real length units in the real world. The browser in our study represents an object's length by referencing to the physical length property defined at modeling when it displays the object. Since objects' lengths are appropriately scaled according to these units, objects can be precisely and visually compared in sire using real world length units. The concept of defining the real length unit is extended to the X3D specification. The units are ranged from $10^{-24}(yotta)\;to\;10^{24}(yocto)$. In addition, we explain the method for processing LOD (Levels Of Detail) and for applying the property of LOLD (Levels of Length Detail) when objects with different LOLD are read into the browser.