• 제어로봇시스템학회논문지
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• 제9권1호
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• pp.82-89
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• 2003

A robust motion control method is proposed fur the point-to-point position control of a XY positioning system which consists of a base cart, elastic ben and moving mass. The horizontal motion controller consists of the feedforward controller to suppress the single mode vibration of the elastic beam and the feedback controller to get the high-accuracy positioning performance of the base cart. Input preshaping vibration suppression method based on system modeling with analytic frequency equation is proposed and integrated into the robust internal-loop compensator(RIC) to increase the robustness of the whole closed-loop system The vertical motion controller is proposed based on the dual RIC structure. Through experiments, it is shown that the proposed method can stabilize the system and suppress the vibration in the presence of uncertainties and disturbances.

• 대한물리의학회지
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• 제8권4호
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• pp.573-582
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• 2013

PURPOSE: The purpose of this study was to establish the reliability and validity of the Wheelchair User's Shoulder Pain Index (WUSPI), which was translated into Korean for long-term wheelchair users. This index measured 15 functional activities, including transfer, self-care, wheelchair mobility and general activities. METHODS: To assess test-retest reliability, 23 long-term wheelchair users completed this self-administered index twice within the same day. Reliability was determined by the intraclass correlation coefficient (ICC), and Cronbach's alpha was used to measure internal consistency. To examine concurrent validity, 21 long-term wheelchair users completed the questionnaire, and we examined the correlation between the index score and the shoulder range of motion measurements. RESULT: The results showed that the intraclass correlation for test-retest reliability of the total index score ranging from .88 to .99 was good to excellent. Additionally, Cronbach's alpha was .96. The internal consistency indicated excellent. Concurrent validity showed negative correlations of total index score to range of motion measurements of shoulder flexion (rho=-.58), extension (rho=-.09), abduction (rho=-.59), external rotation (rho=-.07) and internal rotation (rho=-.3), suggesting a relationship of total index score to loss of shoulder range of motion. CONCLUSION: The Korean WUSPI shows not only high reliability and internal consistency, but also concurrent validity with loss of shoulder flexion and abduction.

• 대한핵의학회지
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• 제24권2호
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• pp.244-253
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• 1990

Sixty-four patients with paradoxical ventricular wall motion noticed both in angiocardiography or 2-dimensional echocardiography were assessed by ECG gated blood pool scan (GBPS). Endless cine loop image, phase and amplitude images and paradox image obtained by visual inspection of each cardiac beat or Fourier transformation of acquired raw data were investigated to determine the incremental value of GBPS with these processing methods for identification of paradoxical ventricular wall motion. The results were as follows: 1) Paradoxical wall motions were observed on interventricular septum in 34 cases, left ventricular free wall in 26 and right ventricular wall in 24. Underlying heart diseases were ischemic (23 cases) valvular(9), congenital heart disease (12), cardiomyopathy (5). pericardial effusion(5), post cardiac surgery(3), col pulmonale (2), endocarditis(1) and right ventricular tumor(1). 2) Left ventricular ejection fractions of patients with paradoxical left ventricular wall motion were significantly lower than those with paradoxical septal motion(p<0.005). 3) The sensitivity of each processing methods for detecting paradoxical wall motion was 76.9% by phase analysis, 74.6% by endless cine loop mapping and 68.4% by paradox image manipultion respectively. Paradoxial motions visualized only in phase, paradox or both images were appeared as hypokinesia or akinesia in cine loop image. 4) All events could be identified by at least one of above three processing methods, however only 34 cases (48.4%) showed the paradoxical molies in all of the three images. By these findings, we concluded that simultaneous inspection of all above three processing methods-endless cine loop, phase analysis and paradox image-is necessary for accurate identification and assessment of paradoxical ventricular wall motion when performing GBPS.

• 한국의학물리학회지:의학물리
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• 제28권4호
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• pp.164-170
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• 2017

One of the methods to consider the effect of respiratory motion of a tumor target in radiotherapy is to establish a treatment plan with the internal target volume (ITV) created based on an accurate analysis of the target motion displacement. When this method is applied to intensity modulated radiotherapy (IMRT), it is expected to yield a different treatment dose distribution under the motion condition according to the IMRT method. In this study, we prepared ITV-based IMRT plans with conventional IMRT using fixed gantry angle beams, RapidArc using volumetric modulated arc therapy, and tomotherapy using helical therapy. Then, the variation in dose distribution caused by the target motion was analyzed by the dose measurement in the actual motion condition. A delivery quality assurance plan was prepared for the established IMRT plan and the dose distribution in the actual motion condition was measured and analyzed using a two-dimensional diode detector placed on a moving phantom capable of simulating breathing movements. The dose measurement was performed considering only a uniform target shape and motion in the superior-inferior (SI) direction. In this condition, it was confirmed that the error of the dose distribution due to the target motion is minimum in tomotherapy. This is thought to be due to the characteristic of tomotherapy that treats the target sequentially by dividing it into several slices. When the target shape is uniform and the main target motion direction is SI, it is considered that tomotherapy for the ITV-based IMRT method has a characteristic which can reduce the dose difference compared with the plan dose under the target motion condition.

• 한국의학물리학회지:의학물리
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• 제23권2호
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• pp.91-98
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• 2012

방사선치료 중 내부 장기의 움직임을 확인하고 이를 보정하는 것은 움직이는 종양에 정확히 방사선을 조사하는데 매우 중요한 역할을 한다. 실제 치료 중 획득한 연속촬영 전자조사 문(cine EPID) 영상을 이용해 치료 중 내부 장기 움직임을 추적하는 오프라인 기반 분석 시스템(IMVS, Internal-organ Motion Verification System using cine EPID)을 개발하였고 모형을 이용하여 개발된 시스템의 정확도와 유용성을 평가했다. IMVS는 cine EPID영상을 이용한 내부 장기 움직임 추적을 위해 내부 표지자를 이용한 유형 정합 알고리즘을 이용했다. 시스템의 성능평가를 위해 폐와 폐 종양을 묘사한 인체 모형과 이를 상하(SI, superior-inferior)방향으로 직선 운동시키는 구동 장치와 제어 프로그램을 고안했다. 모형을 4초 주기로 2 cm 직선 운동 시키면서 10 MV X선으로 3.3 fps, 6.6 fps속도로 cine EPID 영상($1,024{\times}768$ 해상도)를 획득했다. 획득된 cine EPID 영상은 IMVS를 이용하여 표적의 움직임을 추적하고 기존 외부 표지자를 이용한 비디오 영상 기반 추적시스템(RPM, Real-time Position Management, Varian, USA)으로부터 얻은 결과와 비교했다. 정량적 평가를 위해 두 시스템으로부터 움직임의 평균 주기(Peak-To-Peak), 진폭과 패턴(RMS, Root Mean Square)을 측정하여 비교했다. RPM과 IMVS로 측정한 폐 종양 모형의 움직임 주기는 각각 $3.95{\pm}0.02$ (RPM), $3.98{\pm}0.11$ (IMVS 3.3 fps), $4.005{\pm}0.001$ (IMVS 6.6 fps) 초로 실제움직임 주기인 4초와 잘 일치했다. IMVS로 획득한 모형 내부장기의 평균 움직임 진폭은 3.3 fps에서 $1.85{\pm}0.02$ cm, 6.6 fps에서 $1.94{\pm}0.02$ cm으로 실제 진폭 2 cm에 비해 각각 0.15 cm (오차 7.5%) 및 0.06 cm (오차 3%)의 차를 보였다. 움직임 신호의 일치성 평가를 위해 측정한 RMS는 0.1044 (IMVS 3.3 fps), 0.0480 (IMVS 6.6 fps)로 계획된 신호와 잘 일치 했다. cine EPID 영상을 이용하여 내부 표지자의 움직임을 추적하는 IMVS는 모형 실험에서 내부 장기의 움직임을 3% 오차 내에서 확인 가능했다. IMVS는 치료 중 내부장기 움직임을 측정하고 이를 사차원 방사선 치료계획과 비교하여 오차를 보정하는데 기여할 것으로 생각된다.

• 제어로봇시스템학회논문지
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• 제16권9호
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• pp.827-832
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• 2010

Many researchers have tried to detect the falling and to reduce the injury associated with falling. Normally the method of detection of a loss of balance is more efficient than that of a compensatory motion in order to predict the falling. The detection algorithm of the loss of balance was composed of three main parts: parts of processing of measured data, construction of an internal model and detection of the loss of balance. The internal model represented a simple dynamic motion balancing with two rear legs of a four-legged chair and was a simplified model of a central nervous system of a person. The internal model was defined by the experimental data obtained within a fixed time interval, and was applied to the detecting algorithm to the end of the experiment without being changed. The balancing motion controlled by the human brain was improved in process of time because of the experience accruing to the brain from controlling sensory organs. In this study a reconstruction method of the internal model was used in order to improve the success rate and the detecting time of the algorithm and was changed with time the same as the brain did. When using the reconstruction method, the success rate and the detecting time were 95 % and 0.729 sec, respectively and those results were improved by about 7.6 % and 0.25 sec in comparison to the results of the paper of Ahmed and Ashton-Miller. The results showed that the proposed reconstruction method of the internal model was efficient to improve the detecting performance of the algorithm.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권1호
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• pp.95-95
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• 2004

The objectives of this study are to perform extensive analysis on internal mass motion for a wider parameter space and to provide suitable design criteria for a broader applicability for the class of spinning spacecraft. In order to examine the stability criterion determined by an analytical method, some numerical simulations will be performed and compared at various parameter points. (omitted)

• Journal of Chest Surgery
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• 제46권6호
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• pp.457-460
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• 2013

Dynamic left ventricular (LV) outflow tract obstruction is a characteristic feature of hypertrophic cardiomyopathy; however, it can also occur in association with hyperdynamic LV contraction and/or changes in the cardiac loading condition, even in a structurally normal or near-normal heart. Here, we report a case of anemia-induced systolic anterior motion of the mitral valve and the resultant intraventricular obstruction in a patient who underwent coronary artery bypass grafting and suffered from anemia associated with recurrent gastrointestinal bleeding.

• Coupled systems mechanics
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• 제7권3호
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• pp.321-331
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• 2018

When a cantilever beam with a lumped mass at its free end undergoes free transverse vibration, internal axial forces are produced in the beam. Such internal axial forces have an effect on free transverse vibration of the beam. This effect is studied in this paper. The equations of motion for the beam in terms of the generalized coordinates including the effect are derived. The method for determining free transverse vibration of the beam including the effect is presented. In numerical simulations, the results of free transverse vibration of the free end of the beam including and not including the effect are obtained. Based on comparison between the results obtained, the conclusions concerning the effect are given.

• 대한기계학회논문집A
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• 제25권10호
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• pp.1501-1513
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• 2001

Disturbance observer, adaptive robust control, and enhanced internal model control are model based disturbance attenuation methods famous for robust motion controller which can satisfy desired performance and robustness of high-speed/high-accuracy positioning systems. In this paper, these are shown to be the same scheme with different parameterizations. To do this, a generalized framework, called as RIC(robust internal-loop compensator) is proposed and the conventional schemes are analyzed in the RIC framework. Through this analysis, it can be shown that there are inherent similarities between the schemes and advantages of the RIC in the viewpoint of controller design. This is verified through simulations and experiments.