• Title/Summary/Keyword: and resonance

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The Magnetic Resonance (MR) Imaging Features of Myxoid Liposarcoma Arising from the Mesentery: a Case Report

  • Ahn, Taehoon;Lee, Young Hwan;Lee, Guy Mok;Kim, Youe Ree;Yoon, Kwon-Ha
    • Investigative Magnetic Resonance Imaging
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    • v.21 no.4
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    • pp.252-258
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    • 2017
  • Primary mesenteric liposarcoma is rare. It is difficult to make an accurate preoperative diagnosis of the myxoid type of liposarcoma by using imaging such as ultrasound or computed tomography (CT) due to the very small amount of fat that is located in the tumor. We report a case of primary myxoid liposarcoma of the mesentery which was difficult to differentiate from other solid mesenteric tumors with a myxoid component such as low grade fibromyxoid sarcoma, myxoid leiomyosarcoma or myxoma. Use of chemical shift magnetic resonance (MR) imaging to detect small fat components and its cystic appearance with solid components on the MR images can be useful to differentiate myxoid liposarcoma from the other mesenteric tumors with a myxoid component.

The Measurement of the Resonance Frequency of Transducer by Ultrasonic Visualization (초음파의 가시화에 의한 진동자의 공진주파수 측정에 관한 연구)

  • Lee, B.S.;Han, E.K.;Song, C.S.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.13 no.3
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    • pp.14-23
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    • 1993
  • A method to measure the resonance frequency of the ultrasonic transducer which is adhered to the specimen by the ultrasonic visualization is tried. The result shows that the resonance frequency of the transducer adhered to the specimen is lower than the nominal resonance frequency of the transducer in itself and the greater the degree of deviation. It is verified that its cause is the resonance of Al-plate for protecting the transducer by the theoretical analysis.

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Noise Reduction Characteristics of a High-performance Air-gap Resonator (고효율 에어갭 공명기의 소음 저감 특성)

  • Kang, Sang-Wook;Lee, Jang-Moo;Lim, Won-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.2
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    • pp.118-124
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    • 2004
  • The objective of the paper is to demonstrate the noise reduction characteristics of an air-gap resonator, which is composed of an air gap and a partition sheet. By means of installing the air-gap resonator in an enclosed cavity, acoustic resonance can be effectively suppressed using a small space. In particular, it is revealed from a simple, one-dimensional model that the air-gap resonator serves as the Helmholtz resonator that generally absorbs acoustic resonance energy at its resonance frequency. As a result, the air-8ap resonator also has a resonance frequency, which can be predicted with a simple frequency equation derived in the paper. Finally, verification experiments show that the air-gap resonator can be effectively designed by predicting a reasonable gap thickness using the simple frequency-equation.

Undifferentiated Pleomorphic Sarcoma of the Descending Thoracic Aorta Mimicking Pseudoaneurysm with Periaortic Hematoma: a Case Report

  • Kim, Minsu;Bae, Young-A;Byeon, Sun-Ju;Choi, Jung-Ah
    • Investigative Magnetic Resonance Imaging
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    • v.23 no.2
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    • pp.162-166
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    • 2019
  • Undifferentiated pleomorphic sarcoma (UPS) arising from the descending thoracic aorta is a rare type of tumor. To our knowledge, only a few cases have been reported in the literature. We present computed tomography (CT) and magnetic resonance imaging findings of a 43-year-old male patient with undifferentiated pleomorphic sarcoma of the descending thoracic aorta, which showed enhancement on only magnetic resonance imaging (MRI). MRI with contrast enhancement may be useful in differentiating an aortic tumor from atherosclerotic disease.