• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.397-400
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• 2010

The changing light condition of scene cause the luminance fluctuation of the captured image sequences. this artifact is called flicker, and would be easily recognized as visually unstable fluctuation. As the flicker degrades the performance of extracting useful information from image sequences, such as motion information or segmentation, it should be correction and linear flicker model. The algorithm model the flicker effects as a linear system with gain and offset parameter and estimates gain parameter with Gamma correction. The flicker reduction is performed by applying these parameters inversely th the ordinal sequences. To show the performance, we test out algorithm th the ground-truth sequences with the artificially added luminance fluctuation and real sequence with object motion.

• Journal of Broadcast Engineering
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• v.25 no.3
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• pp.428-438
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• 2020

The jitter in the digital videos lowers the visibility and degrades the efficiency of image processing and image compressing. In this paper, we propose a video stabilizer architecture based on triplet CNN and a method of synthesizing training datasets based on video synthesis. Compared with a conventional deep-learning video stabilization method, the proposed video stabilizer can reduce wobbling distortion.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.119-122
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• 1997

움직임 추정(motion estimation)은 압축 부호화나 영상 안정화 시스템, 비젼 시스템 등과 같은 동영상 처리에 있어서 핵심 기술 중의 하나이다. 그러나 기존의 전역 탐색(brute-force) 알고리즘과 같은 움직임 추정 기법은 방대한 양의 계산을 필요로 하기 때문에 처리 시간이 커지고, 하드웨어로 구현하였을 때 회로가 복잡해진다는 문제점을 안고 있다. 본 논문에서는 비트 플레인(bit-plane)에서의 정합을 이용하여 움직임을 추정하는 새로운 기법을 제안한다. 제안된 기법에서는 기존의 전역 탐색 알고리즘을 하나의 비트 플레인으로부터 추출한 이진 영상에 적용함으로써 움직임 추정에 소요되는 계산량을 크게 줄이면서도 우수한 움직임 추정 성능을 갖도록 하였다. 실험 부분에서는 동영상으로부터 카메라의 이동으로 인한 전역적인 움직임을 추정하는데 제안된 기법을 사용한 결과를 제시하였다. 특히 제안된 기법은 비트 플레인을 선정하는데 있어서 적응 기법을 적용하였기 때문에 조도 변화 등과 같은 열악한 환경에서도 안정적으로 동작한다는 것을 실험을 통하여 보였다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.18-24
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• 2008

In this paper we propose a novel method which improves digital image stabilization performance using adoptive selection of motion estimation area. Candidate area for motion estimation is decided and through two processes, multi image reference and edge energy distinction, final motion estimation area is selected. Then Motion estimation and compensation is following in selected area. Experimental results show that proposed method improves performance of digital image stabilization.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.5
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• pp.472-478
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• 2015

This paper describes the design of the active optical compensation movements(at focal plane, secondary mirror) for the image stabilization of a small satellite camera. The movements can correct optical misalignment on-line and directly compensate vibration disturbances in the focal plane. Since the devices are installed inside the space camera, it has an remarkable advantage to deal with the structural deformation of a space camera effectively. In this paper, the requirements of the active optical compensation movements for 1m GSD small satellite camera have been analyzed. Based on the established requirements, the design of the active compensation movements have been conducted. The designed active optical compensation system can control 5 axes movements independently to compensate micro-vibration disturbances in the focal plane and to refocus the optical misaligned satellite camera.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.1
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• pp.58-64
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• 2007

In this paper, the stabilization problem of the image stabilization system(ISS) that captures the image of an object on the ground by remote sensing is considered. The ISS should be stable under outer disturbance such as helicopter vibration for tracking line of sight. Although PID controllers are optimized for the system, disturbances cause the instability of the system. To minimize the effect of the disturbance, the time-delayed control method is used to compensate for uncertainties. Simulation studies are performed and experiments are conducted to confirm the simulation results. Performances of PID control and time-delayed control methods are compared.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.396-399
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• 2003

This paper proposes a simple digital image stabilization(DIS) algorithm for roll motion, which has not been compensated in the 2-axes mechanical stabilization system, using aero-crossing of the rotational motion vectors. The 2-axes stabilization system cannot stabilize rolled images, which causes the deteriorated performance of the object detection and recognition. In this paper, we propose the rotational motion stabilization algorithm which estimates and compensates global motion in terms of rotational center and rotational angle. Both the synthetic images with undesirable rotational disturbance and the real images from 2-axes stabilization system are used to evaluate the proposed algorithm. The results show that our proposed algorithm suppresses the undesirable rotational disturbance effectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.99-100
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• 2016

드론이나 이동형 촬영장비에 장착된 카메라로부터 깨끗하고 안정된 영상을 획득하기 위해서는 짐벌시스템의 안정화기 설계가 필요하다. 짐벌시스템은 카메라 모듈을 지지하는 구조와 외부로 부터의 진동을 차단하면서 정확한 각도를 추종하는 안정화기로 구성된다. 이동형 촬영장비나, 비행중인 드론에는 매우 다양한 주파수 성분의 진동이 발생되는데, 이러한 진동을 제어하기 위하여 6자유도 운동방정식을 유도하고, 이 중에서 본 논문에서는 일반적으로 rolling, pitching, yawing 운동에 대해서는 PID 제어기를 사용하여 안정화를 제어하기만, 카메라종류나 짐벌시스템 구조가 바뀔 때 마다 PID 파라미터를 변경해야 되는 경우가 빈번하다. 본 논문에서는 이런 문제점을 개선하기 새로이 제기된 제어 기법인 지적 PID(intelligent PID) 제어를 통하여 진동제어를 수행하여 짐벌시스템의 안정화를 위한 제어기법을 제안하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.623-626
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• 2009

New ship technology and trapping equipment must be implemented into ship sailing which is currently used nowadays. The day/night camera stability, user interface, track, and remote control system of Jim structure for all over the world should be competitive in the global market. The development equipment sales are losing its competitiveness edge of the existing sailing ship communications equipment due to supply to the aging of the entire system and integration of the development especially for foreign equipment competitor.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.437-442
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• 2015

The swirl ratio in a SI engine is investigated in a steady flow bench according to the measurement methods: an impulse swirl meter and particle image velocimetry (PIV). When measuring the swirl ratio using the PIV, the torque is evaluated based on the cylinder center and swirl center, respectively. The position of the measurement plane is considered. As a result, in the upstream, the swirl ratio measured by the impulse swirl meter is estimated to be larger than that from the PIV measurements due to the unstable vortex motions. Regarding the PIV measurements, the swirl ratio based on the cylinder center has been found to be lower than that based on the swirl center. On the other hand, the difference in swirl ratio has decreased smaller as the measurement plane moved downstream due to the stabilization of the vortex motion.