• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.132-138
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• 2007

MR(magnetic resonance) image of moving organ such as heart shows serious distortion of MR image due to motion itself. To eliminate motion artifacts, MRI(magnetic resonance imaging) scan sequences requires a trigger pulse like ECG(electro-cardiography) R-wave. ECG-gating using cardiac cycle synchronizes the MRI sequence acquisition to the R-wave in order to eliminate image motion artifacts. In this paper, we designed ECG/PPG(photo-plethysmography) gating system which is for eliminating motion artifacts due to moving organ. This system uses nonmagnetic carbon electrodes, lead wire and shield case for minimizing RF(radio-frequency) pulse and gradient effect. Also, we developed a ECG circuit for preventing saturation by magnetic field and a finger plethysmography sensor using optic fiber. And then, gating pulse is generated by adaptive filtering based on NLMS(normalized least mean square) algorithm. To evaluate the developed system, we measured and compared MR imaging of heart and neck with and without ECG/PPG gating system. As a result, we could get a clean image to be used in clinically. In conclusion, the designed ECG/PPG gating system could be useful method when we get MR imaging of moving organ like a heart.

• IEIE Transactions on Smart Processing and Computing
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• 제2권4호
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• pp.203-207
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• 2013

The appropriate handling of motion artifacts is essential for clinical diagnosis in magnetic resonance imaging (MRI). In many cases, motion is an inherent part of MR images because it is difficult to control during MR imaging. As the motion in the human body occur in a deformable manner, they are difficult to deal with. This paper proposes a novel detection method for periodically moving regions to produce MR images with less motion artifacts. When the data is acquired by the radial trajectory, the proposed method can extract the deformable region easily using the difference in the modulated sinograms, which have different periodic phase terms. The simulation results applied to the various cases confirmed the good performance of the proposed method.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1135-1138
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• 2007

This paper presents motion picture artifacts measured with a high-speed camera. Measurement results of the high-speed camera on moving targets will be evaluated and compared with motion blur data derived from step responses measured on stationary test patterns with a spot-photodetector.

• Journal of Magnetics
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• 제21권3호
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• pp.421-424
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• 2016

The purpose of this study is to evaluate an effectiveness of switching turbo direction to improve motion artifacts of small bowels and aorta. From June to October 2015, 60 patients suspected of having Crohn's disease were enrolled. The MR Enterography scans were performed using same protocol other than the turbo direction: with the Z phase encoding (group A) and with Y phase encoding (group B). Qualitative analysis of each group was performed to evaluate the effectiveness of switching turbo direction from Z to Y. As a result, the 5-point Likert scale for paired observers were $2.33{\pm}0.88$ for group A and $3.80{\pm}0.85$ for group B on dynamic contrast enhanced coronal images. In conclusion, group B is proved to be superior to group A and can lessen the motion artifacts derived from phase shifts.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권3호
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• pp.138-141
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• 2006

Blood flow is one of vital signals related to human physiological information. Photoplethysmograph (PPG) has been used to measure indirectly heart rate, blood oxygen saturation ($SpO_2$), and so on. Because PPG signal is weak and sensitive to motion artifacts, it is very important to continuously obtain stable PPG signal during free movement. In this study, we applied the scaled Fourier linear combiner (SFLC) using both the adaptive filter and FLC to remove effectively the motion artifacts as well as background noise in the real time without additional signal correlated with motion from a accelerometer. The proposed method would be useful to reduce the movement and background noise which are not synchronized with heart rate.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1990년도 추계학술대회
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• pp.15-18
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• 1990

In abdominal NMR imaging the respiratory ordering techniques have been successfully used to remove the ghosting artifacts arising from the respiratory motion. In the existing respiratory ordering schemes, however, it is generally accepted that blurring of the moving parts still remains as in the signal averaging technique. A new optimal respiratory ordering scheme which can correct the blurring as well as the ghosting artifacts is theoretically derived through the analysis of the phase encoding directional motion effects in Fourier imaging. The performance of the optimal respiratory ordering scheme is experimentally confirmed together with a suboptimal ordering scheme which is suggested as a compromise for the practicality.

• 한국의류산업학회지
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• 제17권5호
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• pp.844-853
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• 2015

Recently, according to change of lifestyle and increase of concerning in health, needs of the smart clothing based on the vital sign monitoring have increased. Along with this trend, smart clothing for ECG monitoring has been studied various way as textile electrode, clothing design and so on. Smart clothing for ECG monitoring can become a comfortable system which enables continuous vital sign monitoring in daily use. But, smart clothing for ECG monitoring has a weakness on artifact during motion. One of the motion artifact caused by shifting of the electrode position was affected skin change by motion. The aim of this study was to suggest electrode locations for clothing of ECG monitoring to reduce of motion artifacts. Therefore, change of skin surface during the movement were measured and analyzed in order to find location to minimize motion artifacts in ECG monitoring clothing by 3D motion capture. For the experiment, the subjects consisted of 5 males and 5 females in their 20' with average physique. As a result, the optimal location for ECG monitoring was deducted under the bust line and scapula which have least motion artifact. These locations were abstracted to be least affected by movement in this research.

• 대한전자공학회논문지SP
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• 제47권4호
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• pp.1-8
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• 2010

본 논문에서는 효과적인 프레임율 증가 변환을 위한 새로운 방법을 제안하였다. 첫 번째로 제안한 삼중 프레임 기반의 양방향 움직임 추정 방법은 기존의 양방향 움직임 추정 방법에서 발생한 문제점인 유사한 특성을 갖는 이미지에서의 잘못된 움직임 추정을 해결하여 보간 프레임 생성 시 발생한 블록화 현상을 크게 줄일 수 있었다. 두 번째로 제안한 움직임 벡터 평탄화 방법은 시공간적으로 인접한 움직임 벡터들을 고려하여 블록화 현상의 원인이 되는 아웃라이어를 제거할 수 있었다. 실험 결과 제안한 프레임율 증가 변환 방법은 기존의 방법들과 비교했을 때 평균 PSNR이 최대 4.337 dB만큼 높은 것을 확인할 수 있었고, 평균 SSIM은 최대 0.089만큼 높은 것을 확인할 수 있었다.

• 한국게임학회 논문지
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• 제17권1호
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• pp.17-26
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• 2017

최근 실시간으로 모션블러(motion blur)를 위한 연구들은 픽셀당 여러개의 시간 색상을 계산한 후 평균내는 방식으로 샘플의 수가 적을 경우 아티펙트(artifacts)나 노이즈(noise)가 발생하는 문제를 가지고 있다. 본 논문은 이러한 문제를 개선하기 위해서 이동궤적 근사 다면체(motion trail)를 이용한 실시간 모션블러 알고리즘을 제안한다. 본 논문의 알고리즘에서는 현재 프레임과 이전프레임의 삼각형으로 이동궤적 근사 다면체를 만들고 전후 관계(front-to-back) 정렬방법과 시공간차원의 비트연산(bitwise operation)을 적용하여 여러 물체가 겹치는 순간의 가시성 문제를 해결했다. 결과적으로 가려지지 않은 이동궤적 근사 다면체만을 그리기에 매끄러운 블러 효과를 얻는다.

• 한국정밀공학회지
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• 제21권8호
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• pp.164-170
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• 2004

The skin movement artifacts are referred to as the relative motion of skin with respect to the motion of underlying bones. This is of great importance in joint biomechanics or internal kinematics of human body. This paper describes a novel experiment that measures the skin movement of a hand based on MR(magnetic resonance) images in conjunction with surface modeling techniques. The proposed approach consists of 3 phases: (1) MR scanning of a hand with surface makers, (2) 3D reconstruction from the MR images, and (3) registration of the 3D models. The MR images of the hand are captured by 3 different postures. And the surface makers which are attached to the skin are employed to trace the skin motion. After reconstruction of 3D models from the scanned MR images, the global registration is applied to the 3D models based on the particular bone shape of different postures. The results of registration are then used to trace the skin movement by measuring the positions of the surface markers.