• 한국컴퓨터정보학회논문지
• /
• 제27권10호
• /
• pp.19-28
• /
• 2022

본 논문에서는 실시간 고성능 다중 객체 추적을 수행하기 위해 최적의 TBD (Tracking-by-detection) 메커니즘을 결정할 수 있는 Detector Scheduler를 제안한다. Detector Scheduler는 서로 다른 프레임 간의 특징량 차이를 측정하는 것으로 검출기 실행 여부를 결정하여 전체 추적 속도를 향상한다. 하지만, Detector Scheduler의 학습에 필요한 GT (Ground Truth) 생성이 어렵기 때문에 Detector Scheduler를 추적 결과만을 통해 학습 가능한 자가 학습 방법을 제안한다. 제안된 자가 학습 방법은 프레임 간의 객체 카디널리티와 객체 외형 특징량의 비유사도가 커질 때 검출기를 실행할 수 있도록 의사 레이블을 생성하고 제안된 손실함수를 통해 Detector Scheduler를 학습한다.

• 조명전기설비학회논문지
• /
• 제23권11호
• /
• pp.22-27
• /
• 2009

This paper presents a two-paralleled four quadrant DC chopper type PWM power conversion circuit in order to generate a gradient magnetic field in the Magnetic Resonance Imaging (MRI) system. This circuit has 8-IGBTs at their inputs/outputs to realize further high-power density, high speed current tracking control, and to get a low switching ripple amplitude in a controlled current in the Gradient Coils (GCs). Moreover, the power conversion circuit has to realize quick rise/fall response characteristics in proportion to various target currents in GCs. It is proposed in this paper that a unique control scheme can achieve the above objective DSP-based control system realize a high control facility and accuracy. It is proved that the new control system will greatly enlarge the diagnostic target and improve the image quality of MRI.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
• /
• pp.718-723
• /
• 1992

A hydraulic gun/turret servo system requires fast and robust controller performance because of severe operating condition and precise target tracking objective. Digital controllers are able to satisfy this requirement due to high speed electronic device. The purpose of this study is to compare with pre-EPU with new-designed optimal, adaptive controllers by simulating nonlinear hydraulic simulation program. The designed digital controller shows good tracking performance and robustness to disturbance.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2003년도 추계학술대회 논문집
• /
• pp.119-122
• /
• 2003

This paper describes the sensorless technique for the surface-mounted permanent-magent synchronous motor(SPMSM or PMSM) drive based on magnetic saliency. The control technique is a sensorless control algorithm that injects the high frequency voltage to the stator terminal in order to estimate the rotor position and speed. The rotor position and speed for sensorless vector control is achieved by appropriate signal processing to extract the position information from the stator current in the low speed range including zero speed. Proposed sensorless algorithm using the double-band hysteresis controller and initial rotor position detection exhibits excellent reference tracking and increased robustness. Experimental results are presented to verify the feasibility of the proposed control schemes.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1994년도 추계학술대회 논문집
• /
• pp.444-448
• /
• 1994

광 fiber를 이용한 새로운 구조의 초고속 광디스크 드라이버를 제안하였다. 기존의 광 픽 업 모듈을 레리져 다이오드, 광검출기, 렌즈 및 각종 광학계등의 무거운 부분과 GRIN렌즈 및 초경량의 PD로만 구성되는 광 헤드의 가벼운 부분으로 분리하였다. 무거운 부분은 Fixed part로 고정시키고 가벼운 부분만을 Moving part로 함으로써 광 헤드의 tracking 속도를 증가 시켰다. 또한 컴퓨터의 하드디스크 드라이버에서와 같은 초고속의 Pivot-arm tracking방식 을 채용하기 위해 Fixed part와 Moving part를 광 fiber를 이용해 접속하였으며 이 새로운 구 조에서 데이타 신호, tracking 및 focusing 에러 신호를 검출하는 메커니즘에 대해 설명하였다.

• 센서학회지
• /
• 제18권3호
• /
• pp.190-196
• /
• 2009

In a conventional camera system, a target tracking system consists of a camera part and a image processing part. However, in the field of the real time image processing, the vision chip for edge detection which was made by imitating the algorithm of humanis retina is superior to the conventional digital image processing systems because the human retina uses the parallel information processing method. In this paper, we present a high speed target tracking system using the function of the CMOS vision chip for edge detection.

• 대한임베디드공학회논문지
• /
• 제17권6호
• /
• pp.355-365
• /
• 2022

This paper addresses the problem of real-time tracking a high-speed ballistic target. Particle filters can be considered to overcome the nonlinearity in motion and measurement models in the ballistic target. However, it is difficult to apply particle filters to real-time systems because particle filters generally require much computation time. This paper proposes an accelerated particle filter using graphics processing unit (GPU) for real-time ballistic target tracking. The real-time performance of the proposed method was tested and analyzed on a widely-used embedded system. The comparison results with the conventional particle filter on CPU (central processing unit) showed that the proposed method improved the real-time performance by reducing computation time significantly.

• 한국수소및신에너지학회논문집
• /
• 제17권2호
• /
• pp.193-203
• /
• 2006

A high-speed and initial helium jet flow has been analyzed by a developed four-dimensional digital speckle tomography. Multiple high-speed cameras have been used to capture movements of speckles in multiple angles of view simultaneously because a shape of a nozzle for the jet flow is asymmetric and the initial jet flow is fast and unsteady. The speckle movements between no flow and helium jet flow from the asymmetric nozzle controlled by a solenoid valve have been obtained by a cross-correlation tracking method so that those distances can be transferred to deflection angles of laser rays for density gradients. The four-dimensional density fields for the high-speed helium jet flow have been reconstructed from the deflection angles by a developed real-time tomography method.

• 한국멀티미디어학회논문지
• /
• 제5권2호
• /
• pp.215-221
• /
• 2002

광 디스크 장치에서 고배속 모우드로 언밸런스 디스크가 동작될 경우, 진동으로 인한 포커스 및 트래킹 서보가 불안정해져 데이터 검색 시간 지연 및 불안정 동작을 야기한다. 본 논문에서는 이러한 문제점을 해결할 수 있는 방법을 제안한다. 일반적으로 광 디스크 장치에서 사용되고 있는 3 빔 방식의 광 픽업(Piek-up)의 경우, 면진동이나 편심이 있는 디스크 동작시 메인 빔에 따른 포토 다이오드 상의 광 스폿의 위치도 변화된다. 이러한 특성을 이용하여 언밸런스 디스크 동작시 광픽업의 포토 다이오드 A와 C에 수신되는 광량은 디스크의 언밸런스량에 따라 결정되어진다. 따라서 포토다이오드에 수신되는 A와 C의 광량의 변화를 차동 증폭함으로써 디스크의 언밸런스량 검출이 가능하다. 본 연구에서는 고배속 모우드에서 포커스 및 트래킹 서보의 최소 특성을 분석하고, 디스크의 언밸런스량을 전기적인 신호로 검출하는 방법과 검출된 언밸런스량에 따라 광 픽업의 스핀들 모터(Swindle Motor)의 회전수를 조절함으로써 안정적이고 정확한 데이터 검색이 가능한 하드웨어 및 펌웨어 구조를 제안하였다.

• 대한기계학회논문집A
• /
• 제30권1호
• /
• pp.32-41
• /
• 2006

We analyzed the non-Newtonian and non-isothermal flow in the melt conveying zone in co-rotating and counter-rotating screw extruder system with the commercial code, STAR-CD, and compared the mixing performance with respect to screw speed and rotating direction. The viscosity of fluid was described by power-law model. The dynamics of mixing was studied numerically by tracking the motion of particles in a twin screw extruder system. The extent of mixing was characterized in terms of the residence time distribution and average strain. The results showed that high screw speed decreases the residence time but increases the shear rate. Therefore higher screw speed increases the strain and has better mixing performance. Counter-rotating screw extruder system and co-rotating screw extruder has the similar shear rate with the same screw speed in spite of different rotating direction. However, the counter-rotating screw has good mixing performance, which is resulted from longer residence time than that of co-rotating screw extruder.