• 제목/요약/키워드: J-Estimation

검색결과 1,379건 처리시간 0.079초

Blood Pulsation의 효과가 뇌 활성화에 미치는 영향을 알아보는 방법 (Estimation Method for Brain Activities are Influenced by Blood Pulsation Effect)

  • 이원호;구정훈;이형래;한기완;박진식;김재진;윤강준;김인영;김선일
    • 대한의용생체공학회:의공학회지
    • /
    • 제28권3호
    • /
    • pp.338-343
    • /
    • 2007
  • BOLD T2*-weighted MR images reflects cortical blood flow and oxygenation alterations. fMRI study relies on the detection of localized changes in BOLD signal intensity. Since fMRI measures the very small modulations in BOLD signal intensity that occur during changes in brain activity, it is also very sensitive to small signal intensity variations caused by physiologic noise during the scan. Due to the complexity of movement of various organs associated with heart beat, it is important to reduce cardiac related noise rather than other physiological noise which could be required with relatively simple method. Therefore, a number of methods have been developed for the estimation and reduction of cardiac noise in fMRI study. But, each method has limitation. In this study, we proposed a new estimation method for brain activities influenced by blood pulsation effect using regression analysis with blood pulsation signal and the correspond slice of fMRI. We could find out that the right anterior cingulate cortex and right olfactory cortex and left olfactory cortex were largely influenced by blood pulsation effect for new method. These observed areas are mostly on the structure of anterior cerebral artery in the brain. That is convinced with that our method would be valid and our new method is easier to apply in practice and reduce computational burden than the retrospective method.

CFRP 적층판의 동적 층간파괴인성의 평가법 (A Study on the Estimation of Dynamic Interlaminar Fracture Toughness on CFRP Laminates Plates)

  • 김지훈;김영남;판부직규;양인영
    • 한국자동차공학회논문집
    • /
    • 제6권2호
    • /
    • pp.80-91
    • /
    • 1998
  • In this paper, the estimation of dynamic interlaminar fracture toughness on fracture mode II in CFRP(carbon fiber reinforced plastics) laminates in made. Dynamic ENF(End Notched Flexure) apparatus used in this paper is manufactured by suing Split Hopkinson Pressure Bar. The static and impact load history in the CFRP specimen is measured by using manufactured dynamic ENF tester and 3-point bending test is carried out to find the load history. Also dynamic interlaminar fracture toughness can be found by using the J integral obrained from dynamic analysis in consideration of intertia-force effect.

  • PDF

전문가 시스템을 이용한 부하 구성비 추정 (Estimation of Load Composition by Expert System)

  • 김정훈;임재윤;이재혁;김형섭
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 1991년도 하계학술대회 논문집
    • /
    • pp.345-349
    • /
    • 1991
  • The accurate simulation of the static and/or dynamic response of a power system requires detailed knowledge of the behavior of the loads. For the Precise load model, the chearacteristics and the composition of the load are needed. In this papers, the reliable estimation method of load composition is suggested intruducing knowledge-based system though it used various weekly-reliable survey data.

  • PDF

인덕턴스 추론기법에 의한 SRM의 센서리스 제어 (Sensorless Control of SRM using Inductance Estimation Thechnique)

  • 문재원;박성준;안진우;김철우;황영문
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
    • /
    • pp.137-139
    • /
    • 2001
  • This paper describes a new methods of detecting rotor position in SRM(switched reluctance motor). The Conventional method of position sensorless control for SRM is measuring phase current and pulse voltage applied in unexcited phase. The estimation of rotor position based on the detection of inductance by pulse current. Implementation is via low-cost electronic circuits with DSP320F241. Test results show that this technique is a possible approach to detect the rotor position of an SRM.

  • PDF

새로운 인덕턴스 연산에 의한 SRM 회전자 위치 검출 (The Rotor Position Detection of SRM with the Novel Inductance Estimation)

  • 나종덕;김지훈;변문걸;최연옥;백형래;조금배
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
    • /
    • pp.229-231
    • /
    • 2005
  • A sensorless control scheme for the switched reluctance motor (SRM) drive at speed control is presented in this paper. In this paper proposes a very simple method to estimate the rotor position of a switched reluctance motor. By on-line estimating the self-inductance of the motor, the rotor position of the SR motor is obtained, and a closed-loop drive system can be achieved. Proposed methods can easy implement to application with sensorless SR motor drive system. SR motor simulation executed with self inductance estimation and result represented.

  • PDF

궤도 기하학 기반 바이어스 추정기법을 이용한 저궤도 위성의 유도자기장 바이어스 분석 (Analysis of Induced Magnetic Field Bias in LEO Satellites Using Orbital Geometry-based Bias Estimation Algorithm)

  • 이선호;용기력;최홍택;오시환;임조령;김용복;서현호;이혜진
    • 한국항공우주학회지
    • /
    • 제36권11호
    • /
    • pp.1126-1131
    • /
    • 2008
  • 본 논문은 궤도 기하학 기반 바이어스 추정기법을 다목적실용위성 1호 및 2호의 자기센서 측정데이터에 적용하여 위성체 태양전지판과 전장박스에서 발생하는 유도자기장 바이어스를 추정한다. 유도자기장 바이어스의 추정과 적절한 보정은 자기센서의 노후화를 대처하고 수명을 최대한 연장하여 정상적으로 위성 임무를 수행을 가능하게 한다.