• 제목/요약/키워드: Internal resonance

검색결과 667건 처리시간 0.026초

Magnetization Transfer Contrast Angiography for Organized Thrombosed Intracranial Aneurysm in TOF MR Angiography: a Case Report

  • Kang, Dong-Hun;Lee, Hui Joong
    • Investigative Magnetic Resonance Imaging
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    • 제22권4호
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    • pp.266-271
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    • 2018
  • A 66-year-old woman was referred for treatment of incidental detection of two intracranial aneurysms. Time-of-flight MR angiography (TOF MRA) revealed two aneurysms at the M1 segment of the right middle cerebral artery, and clinoid segment of left internal carotid artery, respectively. On digital subtraction angiography, there was a saccular aneurysm on the left internal carotid artery, but the other aneurysm was not detected on the right middle cerebral artery. Based on comprehensive review of imaging findings, organized thrombosed aneurysm was judged as the most likely diagnosis. In the presented report, magnetization transfer (MT) pulse to TOF MRA was used, to differentiate aneurysm-mimicking lesion on TOF MRA. We report that MT technique could be effective in differentiating true aneurysm, from possible T1 high signal artifact on TOF MRA.

자기공명영상을 이용한 농축산물의 비파괴 내부품질 평가 (Nondestructive Internal Quality Evaluation of Agricultural Products using Magnetic Resonance Imaging)

  • 김성민
    • Journal of Biosystems Engineering
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    • 제24권6호
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    • pp.523-530
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    • 1999
  • 자기공명영상 (MRI)기법은 최근에 그의 이용 분야가 식품공학 및 농학 분야까지 확대되고 있다. 이 연구에서는 MRI의 기본 원리를 알아보고 어떤 요인들이 자기공명영상의 명암을 결정하는지 알아 보았다. MRI를 이용하여 비파괴적인 방법으로 농축산물의 내부 구조 영상을 얻고 이로부터 토마토의 내부 공동, 감자의 공동병, 사과와 파파야의 멍, 버찌씨의 유무, 망고와 감자의 벌레에 의한 손상, 망고와 마늘의 내부 결함, 키위의 성숙도에 따른 변화, 그리고 소고기의 내부 구조 둥을 판별할 수 있음을 알아 보았으며 농축산물의 품질을 결정짓는 이러한 내부 요인들이 어떻게 자기공명영상을 형성하는지 알아 보았다. 대상 시료에 따라 적당한 자기공명영상 인자(TR과 TE)를 선택하여야 한다. 또한 특정 인자를 강조하기 위해서는 최적의 자기공명영상 인자를 선택하여야 한다.

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Linearized analysis of the internal pressures for a two-compartment building with leakage

  • Yu, Xianfeng;Gu, Ming;Xie, Zhuangning
    • Wind and Structures
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    • 제28권2호
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    • pp.89-97
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    • 2019
  • The non-linear equations governing wind-induced internal pressures for a two-compartment building with background leakage are linearized based on some reasonable assumptions. The explicit admittance functions for both building compartments are derived, and the equivalent damping coefficients of the coupling internal pressure system are iteratively obtained. The RMS values of the internal pressure coefficients calculated from the non-linear equations and linearized equations are compared. Results indicate that the linearized equations generally have good calculation precision when the porosity ratio is less than 20%. Parameters are analyzed on the explicit admittance functions. Results show that the peaks of the internal pressure in the compartment without an external opening (Compartment 2) are higher than that in the compartment with an external opening (Compartment 1) at lower Helmholtz frequency. By contrast, the resonance peak of the internal pressure in compartment 2 is lower than that in compartment 1 at higher Helmholtz frequencies.

Global Bifurcations and Chaos Via Breaking of KAM Tori of an Harmonically Excited Imperfect Circular Plate

  • Samoylenko, S.B.;Lee, W.K.
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 춘계학술대회논문집
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    • pp.419-422
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    • 2005
  • Global bifurcations and chaos in modal interactions of an imperfect circular plate with one-to-one internal resonance are investigated. The case of primary resonance, in which an excitation frequency is near natural frequencies, is considered. The damping force is not included in the analysis. The renormalization-group technique for KAM tori is used to obtain the criteria for large-scale stochasticity in the system.

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Quantitative Analysis of Chloride by Heteronuclear Electronic Reference NMR Method

  • Lee, Sueg-Geun
    • 한국자기공명학회논문지
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    • 제11권2호
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    • pp.115-121
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    • 2007
  • A new quantitative analysis of chloride by the HERETIC NMR method which does not need internal or external references was described. The results showed that the use of HERETIC peak corresponding $500\;{\mu}g/mL$ of chloride calibration showed less than 4 % standard deviations from 50 to $5000\;{\mu}g/mL$ range of chloride concentrations.

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Global Bifurcations and Chaos in an Harmonically Excited and Undamped Circular Plate

  • ;이원경
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 추계학술대회논문집
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    • pp.140-144
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    • 2004
  • Global bifurcations and chaos in modal interactions of an imperfect circular plate with one-to-one internal resonance are investigated. The case of primary resonance, in which an excitation frequency is near natural frequencies, is considered. The damping force is not included in the analysis. The Melnikov's method for heteroclinic orbits of the autonomous system was used to obtain the criteria for chaotic motion.

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Time-Resolved Resonance Raman Spectroscopic Study on Metallotetraphenylporphyrins: Effects of Metal Sizes

  • 정새채;김동호;조대원;윤민중
    • Bulletin of the Korean Chemical Society
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    • 제20권6호
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    • pp.657-662
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    • 1999
  • The variation of Jahn-Teller(J-T) distortion imposed on various metallo- tetraphenylporphyrins(MTPPS;M=ZnⅡ,PdⅡ,PtⅡ,and RhⅢ) has been investigated by time-resolved resonance Raman spectroscopy. B1g and B2g modes of the triplet(π,π*) states for the heavy-metal porphyrins exhibit the enhancement of their intensities compared with those of 3ZnⅢTPP, while the enhancement of phenyl internal mode is reduced. These results suggest that the J-T distortion becomes manifest as the metal size increases, and consequently the porphyrin-to-phenyl ring charge transfer in the excited triplet state is inhibited.

요크셔테리어에서 발생한 난소 유두모양샘암종 (Ovarian Papillary Adenocarcinoma in a Yorkshire Terrier Dog)

  • 조수경;강병택;박철;유종현;정동인;임채영;이종환;우응제;박희명
    • 한국임상수의학회지
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    • 제24권2호
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    • pp.251-254
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    • 2007
  • 10년령의 중성화되지 않은 암컷 요크셔테리어가 심한 복부확장과 출혈성 삼출물에 대한 평가를 위해 내원하였다. 복부 방사선과 초음파 검사상에서 삼출물과 무에코의 낭성 구성물 들을 지닌 복강 내 종괴가 확인되었다. 복수의 세포검사에서 공포화된 세포질을 지닌 종양성 외피 세포들과 현저한 핵들이 관찰되었다. 자기공명영상에서는 잘 분획되고, 이질성의 큰 종괴가 복강 내를 채우고 있었다. 부검 상에서는 우측 난소로부터 유래한 큰 종괴가 관찰되었다. 조직병리학적 검사에서는 종양성 외피세포들로 이루어진 유두모양 구조들로 종괴가 구성되어있는 것을 확인 할 수 있었다. 환견은 임상 및 조직병리학적 소견들에 근거하여 유두모양의 악성 난소 샘암종으로 최종 진단되었다.