• 한국통신학회논문지
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• 제32권4C호
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• pp.396-400
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• 2007

본 논문은 고속 PDE 알고리즘을 제안한다. 기존 PDE 알고리즘이 부분 정합오차를 이용해 후보블록의 나머지 정합 과정을 생략할 수 없을 때 제안된 알고리즘은 계산된 부분 정합오차로부터 예측된 블록 정합오차를 이용해 다시 한번 나머지 정합 과정을 생략하는 것을 평가한다. 예측된 블록 정합오차는 부분 정합오차보다 항상 크므로 제안된 알고리즘은 기존 PDE보다 일찍 불가능한 후보 블록을 제거할 수 있다. 모의 실험의 결과들은 제안된 알고리즘이 기존 PDE 정도의 화질을 유지하면서 계산량을 크게 줄여주는 것을 보여준다.

• 한국정밀공학회지
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• 제30권12호
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• pp.1281-1286
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• 2013

In this paper, a miniaturized stage with two prismatic-prismatic joints (2-PP) type parallel compliant mechanism driven by piezo actuators is proposed. This stage consists of two layers which are a motion guide layer and an actuation layer. The motion guide layer has 2-PP type parallel compliant mechanism to guide two translational motions, whereas the actuation layer has two leverage type amplification mechanisms and two piezo actuators to generate forces. Since the volume of the stage is too small to mount displacement sensors, the piezo actuators embedding strain gauge sensors are chosen. With the strain gauge-embedded piezo actuators, a semi-control is implemented, which results in hysteresis compensation of the stage. As the results, the operating range of $30{\mu}m$, the resolution of 20 nm, and the bandwidth of 400 Hz in each axis were obtained in the experiments.

• 한국전자파학회논문지
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• 제26권11호
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• pp.1027-1030
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• 2015

항공 SAR(Synthetic Aperture Radar)에서는 일반적으로 바람과 같은 외부 영향에 의해 발생한 요동으로 인해 해상도가 저하될 뿐만 아니라, 사이드로브가 증가하게 되어 영상 화질이 저하되므로 본 논문에서는 사이드로브를 감소시키기 위한 기법을 제시한다. 이를 위해 비행경로를 분할한 다음, 분할된 경로에서 획득된 각각의 데이터에 대해 스퀸트 각도를 추정하여 임무영역을 계산한다. 또한, 재설정된 임무영역 중심에 대하여 1차 요동보상을 수행한 후, 생성된 SAR 영상에서 사이드로브 영향이 두드러지는 영역을 추출한 다음에, 사이드로브 감소 필터를 반복적으로 적용한 후 전체 영상에 대해 확장하여 영상 화질을 향상시키는 방법을 제시한다.

• 한국콘텐츠학회논문지
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• 제7권12호
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• pp.303-310
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• 2007

영상을 통신망에서 실시간 전송하려면 압축된 비디오 비트열이 필요하다. 비디오 압축 알고리즘은 시간적, 공간적, 확률적 중복성을 제거하기 때문에 부호화된 비트열은 전송과정 중에 발생하는 전송에러에 매우 민감한 특성을 보인다. 본 논문에서는 저 전송률 비디오 코딩에서 에러의 확산을 막기 위한 에러 복원코딩 방식을 제안한다. 이런 에러 복원 코딩 기술의 성능은 전송에러를 얼마나 정확하게 탐지해 내느냐에 달려 있는데, 전송 에러를 검출하기위해 데이터 숨김이라는 방식을 제안한다. 그리고 에러가 발생한 매크로블록을 복원하기 위해 인트라 매크로블록 갱신 기술과, 움직임 벡터 예측을 이용한 움직임 보상 기술을 적용하여 성능을 비교 및 평가한다. 이 방식은 WCDMA와 같이 에러가 발생할 확률이 있는 비디오 전송망에서 사용할 경우 매우 효과적이다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.618-622
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• 2009

An improvement of standard encoder has been saturated recently. However, new coding method does not have a compatibility with conventional standard. To solve this problem, new concept coding method that has a semicompatibility with standard may be discussed. On the other hand, cyclic Intra-picture coding is used for access and refreshment. However, I-picture spend large amount of bits. An enhancement of I-picture is desired with keeping its refreshment performance. Further, it's a problem that quality change at the border of GOP because of its independency. To respond these, we propose the coding which is applied an inter-frame processing at the border of GOP. Applied method is the reduction of quantization error using the motion compensated inter-picture processing. In this report, we check the improvement of the efficiency and the compatibility of proposed method. As a result of examination, we recognize that the total gain is maximally 1.2dB in PSNR. Generally, the degradation of performance in standard decoding is smaller than its gain. Also the refreshment performance is tested.

• 대한의용생체공학회:의공학회지
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• 제15권4호
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• pp.377-382
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• 1994

In the conventional Fourier imaging method in MRI (Magnetic Resonance Imaging), intramotion such as pulsatile flow makes zipper-like artifact along the phase encoding direction. On the other hand, line-integral projection reconstruction (LPR) method has advantages such as imaging of short T2, object and reduction of the flow artifact by elimination of the flow-induced phase fluctuation. The LPR, however, necessarily requires time consuming filtering and back-projection processes, so that the reconstruction takes long time. To overcome the long reconstruction time of the LPR and to obtain the flow artifact reduction effect, we adopted phase corrected concentric square raster sampling (CSRS) method and improved its imaging performance. The CSRS is a fast reconstruction method which has the same properties with the LPR. In this paper, we proposed a new method of flow artifact reduction using the CSRS method. Through computer simulations and experiments, we verified that the proposed method can eliminate phase fluctuations, thereby reducing the flow artifact and re- markably shorten the reconstruction time which required long time in the LPR.

• 한국기계가공학회지
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• 제17권1호
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• pp.63-68
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• 2018

At present, ultra-precision cutting technology has been studied in Korean research institutes, focusing on development of ultra-precision cutting tool technology and ultra-precision control engineering. However, the developed technologies are still far behind advanced countries. It focuses on metals including aluminum, copper and nickel, and nonmetals including plastics, silicone and germanium which require high precision while using a lathe. It is hard to implement high precision by grinding the aforementioned materials. To address the issue, the ultra-precision cutting technology has been developing by using ultra-precision machine tools very accurate and strong, and diamond tools highly abrasion-resistant. To address this issue, this study aims to conduct ultra-precision cutting by using ECTS (Error Compensation Tool Servo) to improve motion precision of elements and components, and compensate for motion errors in real time. An IR camera is used for analyzing cutting accuracy differences depending on the heat generated in diamond tools in cutting to examine the heat generated in cutting to study cutting accuracy depending on generated heat.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.381-382
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• 2007

Recently fishing industry is interested in efficient and automated fishing implementations to reach the level of the international leading technology. One of the important device used in fishing boat is an automated electric compass that harnesses the GPS and terrestrial magnetic sensor. The electric compass is desired to be minimized in size while keeping a high effectiveness in the characteristic of a magnetic compass. This device also can be used as a heading angle sensor to construct auto-navigation system in a small size of ships. However, there exists measurement errors induced from the slope of terrestrial magnetic sensor caused by the motion of boat. In this paper, a method has been proposed removing the measurement error arising from the slope of terrestrial magnetic sensor when the ship is in motion. We have designed a sensor with two DOF(degree of freedom) and a weight to maintain the horizontality of the sensor. Through this research, the hardware has been designed and also a test has been performed. The test shows a promissory result.

• 정보처리학회논문지B
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• 제12B권4호
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• pp.403-412
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• 2005

본 논문에서는 비디오 데이터로부터 장면 사이의 경계를 검출하고, 이들을 그 종류별로 분류하는 장면전환 검출 방법을 제안한다 제안한 장면전환 검출 방법은 급진적인 장면전환인 컷(cut)과 점진적인 장면전환인 페이드(fade) 및 디졸브(dissolve)를 검출한다. 본 논문에서는 영상 내에 포함된 카메라의 동작 정보를 이용하여 영상을 보정하고, 보정된 영상으로부터 특징을 추출하여 장면전환을 검출한다. 따라서 카메라의 동작으로 인해 기인하는 여러 가지 오 검출을 방지한다. 또한, 영상을 보정하는 과정에서 지역적인 이동 물체의 동작을 제거하므로 이동 물체의 동작으로 인해 기인하는 장면전환의 오 검출도 방지한다. 실험에서는 다양한 비디오 데이터를 입력 받아 기존의 장면전환 검출 방법들과 제안한 방법의 성능을 비교 분석함으로써 제안한 방법의 우수함을 보인다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.754-758
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• 2000

In recent years, the LDM(Linear DC Motor) is widely used, because it has more merits than other rotary motors. First, if system requires linear motion, LDM realizes direct linear motion as rotary motor does not. Second, system is simple and easy to control, and so on. In optical disc drive, a tracking system consists of two parts. One is fine actuating and the other is coarse actuating. For coarse actuating VCM(Voice Coil Motor) actuator is used as a basic drive mechanism. In this paper, MC(Moving Coil) type LDM is designed, manufactured and controlled. System is composed of mechanical-electromagnetic component, therefore mechanical loss and electromagnetic loss exist. The dominent mechanical loss is friction which results from sliding between guide shaft and hole. Therefore, this paper shows the friction compensation control. High speed and accurate position is not gained only PID control, therefore other control method is applied to the system.