• Journal of KSNVE
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• v.8 no.2
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• pp.336-345
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• 1998

The dynamic instability of cylindrical shell with clamped-free boundary condition subjected to constant follower force or $P_0 + P_1cos {\Omega}_t$ type pulsating follower force is analyzed. The motion of shell is modeled using the shell theory considering rotary inertia and shear deformation, and analyzed with finite element method. In case of constant follower force, the changes of eigenvalues dependent on the magnitude of applied load are investigated and the critical loads are obtained. In case pulsating follower force, instability regions of exicitation frequency are obtained by modal transform with right and left modal matrix and by multiple scales method. The effects of thickness ratio and aspect ratio on the instability of shell are studied.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.197-200
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• 2009

영상 압축은 멀티미디어 전송에 있어 핵심적인 기술이다. 동영상 압축 기술 중 움직임 예측부는 전체 동영상 압축 부호화에서 가장 복잡한 부분으로, 멀티미디어의 실시간 전송을 위하여 고속 알고리듬이 필요한 부분이다. 본 논문은 기존의 고속 움직임 예측 알고리듬의 하나인 이진 블록 정합 움직임 예측 알고리듬을 개선하여 더욱 빠른 속도의 알고리듬을 제안한다. 제안하는 알고리듬은 웨이블릿 변환 후 고주파 대역의 정보값을 조기 움직임 예측 중지 조건으로 사용하여 기존의 알고리듬을 개선한다. 제안하는 알고리듬은 기존의 알고리듬의 속도를 개선하는 동시에 화질을 유지시킨다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.299-302
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• 2010

영상 압축은 멀티미디어 전송에 있어 핵심적인 기술이다. 동영상 압축 기술 중 움직임 예측부는 전체 동영상 압축 부호화에서 가장 복잡한 부분으로, 멀티미디어의 실시간 전송을 위하여 고속 알고리듬이 필요한 부분이다. 본 논문은 기존의 고속 움직임 예측 알고리듬의 하나인 이진 블록 정합 움직임 예측 알고리듬을 개선하여 더욱 빠른 속도의 알고리듬을 제안한다. 제안하는 알고리듬은 웨이블릿 변환 후 새로운 커널을 적용하여 기존의 알고리듬을 개선한다. 제안하는 알고리듬은 기존의 알고리듬의 속도를 유지하면서 화질을 개선시킨다.

• Coupled systems mechanics
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• v.6 no.2
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• pp.175-187
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• 2017

This paper deals with a uniform cantilever Euler-Bernoulli beam subjected to follower and transversal force at its free end as a model for a pipe conveying fluid under electromagnetic damper force. The electromagnetic damper is composed of a permanent-magnet DC motor, a ball screw and a nut. The main objective of the current work is to reduce the pipe vibration resulting from the fluid velocity and allow it to transform into electric energy. To pursue this goal, the stability and vibration of the beam model was studied using Ritz and Newmark methods. It was observed that increasing the fluid velocity results in a decrease in the motion of the free end of the pipe. The results of simulation showed that the designed semiactive electromagnetic damper controlled by on-off damping control strategy decreased the vibration amplitude of the pipe about 5.9% and regenerated energy nearly 1.9 (mJ/s). It was also revealed that the designed semi-active electromagnetic damper has better performance and more energy regeneration than the passive electromagnetic damper.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.42-49
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• 2006

In this paper, an efficient piezoelectric passive damper is newly devised to suppress the multi-mode vibration of plates. To construct the passive damper, the piezoelectric materials are utilized as energy transformer, which can transform the mechanical energy to electrical energy. To dissipate the electrical energy transformed from mechanical energy, multiple resonant shunted piezoelectric circuits are applied. The dynamic governing equations of a coupled electro-mechanical piezoelectric with multiple piezoelectric patches and multiple resonant shunted circuits is derived and solved for the one edge clamped plate. The equations of motion of the piezoelectrics and shunted circuits as well as the plate are discretized by finite element method to estimate more exactly the effectiveness of the piezoelectric passive damper. The method to find the optimal location of a piezoelectric is presented to maximize effectiveness for desired modes. The electro-mechanical coupling term becomes important parameter to select the optimal location.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.582-584
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• 2011

This paper presents a Channel DiVision (CDV) scheme for transform-domain distributed video coding. In the proposed system, we employ the symmetric motion estimation to generate high quality side information for Wyner-Ziv (WZ) frames. Also, the decoder estimates the distortion of the side information, which is used to classify the transmitting channels for WZ frames. Each channel has a different expected noise. Then, the encoder allocates an appropriate number noise. Then, the encoder allocates an appropriate number present rate-distortion performance results and comparisons with existing state-of-the-art algorithms and H.264.

• The Journal of the Korea Contents Association
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• v.7 no.5
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• pp.10-15
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• 2007

This paper proposes the method that detects abnormal trajectory of fish with tracking data. And it is obtained by automatic tracking system based on conventional computer vision. Also, we analyze the trajectory using subband frequency features through DWT(Discrete Wavelet Transform). Through experimental results, we confirm that our results have some statistical means. The proposed method demonstrates that DWT is useful method for detecting presence of toxicoid features in environment as for an alternative of bio-monitoring tool.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.459-462
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• 2000

The analysis of distribution line faults is essential to the proper protection of power system. A high impedance fault(HIF) dose not make enough current to cause conventional protective device operating. so it is well hon that undesirable operating conditions and certain types of faults on electric distribution feeders cannot be detected by using conventional protection system. In this paper, we prove that the nature of the high impedance faults is indeed a deterministic chaos, not a random motion Algorithms for estimating Lyapunov spectrum and the largest Lyapunov exponent are applied to various fault currents detections in order to evaluate the orbital instability peculiar to deterministic chaos dynamically, and fractal dimensions of fault currents which represent geometrical self-similarity are calculated. Wavelet transform analysis is applied the time-scale information to fault signal. Time-scale representation of high impedance faults can detect easily and localize correctly the fault waveform.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2350-2355
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• 2005

In this paper, we introduce biped walking robot which can static walking with 22 degree-of-freedoms. The developed biped walking robot is 480mm tall and 2500g, and 22 RC servo motors are used to actuate. Before made an active algorithm, we generated the motions of robot with the motion simulator which developed using by C language. The two dimension simulator is Based on the inverse kinematics and D-H transform. The simulator implements various motions as inputted the ankle's trajectory. Also we developed a simulator which is applied the principle of inverted pendulum to acquires the center of gravity. As we use this simulator, we can get the best appropriate angle of ankle and pelvis when the robot lifts up its one side leg during the working. We implement the walking motions which is based on the data(angle) getting from both of simulators. The robot can be controlled by text shaped command through RF signal of wireless modem which connected with laptop computer by serial cable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.5
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• pp.1096-1108
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• 1996

In this paper, we propose a temporal adaptive tranform 3D SBC coder with motion compensation, exploiting redundancy in the temporal domain. We propose a temporal adaptivity measure, by which the R-D optimal temporal transform can be chaosen. The base temporal subband frame is coded using H.261-like MC-DCT coder, while the higher temporal subband frames are coded using the 2D adaptive wavelet packet bases, considering the various energy distribution which results from the temporal variation. In encoding the subbands, we employ adaptive scanning methods, uniform step-size quantization with VLC, and coded/not-coded flag reduction technique using the quadtree structure. From the simulation results, the proposed adaptive 3D subband coder shows about 0.29~3.14 dB gain over the H.261 and the fixed 3D subband coder techniques.