• Journal of the Korean Wood Science and Technology
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• 제42권6호
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• pp.723-731
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• 2014

공진주파수 모드를 이용하는 비파괴 평가기술법을 거대억새 파티클 보드를 페놀수지로 함침한 후 탄화온도별(600, 800, 1000, $1200^{\circ}C$)로 제조한 세라믹에 적용하였다. 동적 탄성계수와 정적 휨 탄성계수는 탄화온도가 증가할수록 증가하였다. 휨 강도에 대한 동적 탄성계수 및 정적 휨 탄성계수는 밀접한 상관관계를 나타내었다. 그러나 휨 강도에 대한 상관관계에서 정적 탄성계수 보다 동적 탄성계수가 더 밀접한 상관관계를 나타내었다. 따라서 공진 주파수 모드를 사용하는 동적 탄성계수측정법으로 소성온도에 따라 제조된 거대억대 파티클보드의 휨 강도를 예측하는 비파괴 평가 방법으로 유용할 것으로 판단된다.

• 농업생명과학연구
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• 제46권1호
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• pp.35-41
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• 2012

공진주파수 모드를 이용하는 비파괴 평가기술법을 닥나무를 소성온도별(600, 800, 1000, $1200^{\circ}C$)로 제조한 우드세라믹에 적용하였다. 공진주파수 및 동적 탄성계수는 소성온도가 증가할수록 증가하였다. 동적 탄성계수 및 정적 휨 탄성계수와 휨강도사이에는 밀접한 상관관계가 나타났다. 따라서 공진 주파수 모드를 사용하는 동적 탄성계수측정은 소성온도에 따라 제조된 우드세라믹의 휨강도를 예측하는 비파괴 평가 방법으로 유용할 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1115-1119
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• 2005

The paper proposes the elastic modulus evaluation technique of a cantilever beam by vibration analysis based on time-average electronic speckle pattern interferometry (TA-ESPI) with non-contact and nondestructive and Euler-Bernoulli equation. General approaches for the measurement of elastic modulus of thin film are Nano indentation test, Bulge test and Micro-tensile test and so on. They each have strength and weakness in the preparation of test specimen and the analysis of experimental result. ESPI has been developed as a common measurement method for vibration mode visualization and surface displacement. Whole-field vibration mode shape (surface displacement distribution) at a resonance frequency can be visualized by ESPI. And the maximum surface displacement distribution from ESPI is a clue to find the resonance frequency at each vibration mode shape. And the elastic modules of test material can be easily estimated from the measured resonance frequency and Euler-Bernoulli equation. The TA-ESPI vibration analysis technique is able to give the elastic modulus of materials through the simple processing of preparation and analysis.

• Investigative Magnetic Resonance Imaging
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• 제14권1호
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• pp.1-9
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• 2010

여성골반 질환 영역에 있어서 초음파가 적은 비용과 안전성 등의 이유로 가장 흔히 이용되는 최우선적 검사라 한다면 MRI는 정확한 진단과 치료 결정을 위한 중요한 정보를 제공하는 최선의 영상검사로 이미 널리 이용되고 있다. 여성 골반 MRI의 적응증은 광범위하지만 선천성 기형, 자궁 및 난소 종양의 양성 및 악성 감별진단, 악성 자궁 및 난소 종양의 병기 결정 등에 주로 사용되고 있다. 따라서 여성골반 질환의 정확한 진단과 치료 방침 결정에 있어 각각의 질환에 따른 최적의 영상을 얻기 위한 MRI 프로토콜에 대한 이해가 중요하다.

• 한국의학물리학회지:의학물리
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• 제31권4호
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• pp.189-193
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• 2020

An MR-based attenuation correction (MRAC) map plays an important role in quantitative positron emission tomography (PET) image evaluation in PET/magnetic resonance imaging (MRI) systems. However, the MRAC map is affected by the magnetic field inhomogeneity of MRIs. This study aims to evaluate the characteristics of MRAC maps of physical phantoms on PET/MRI images. Phantom measurements were performed using the Siemens Biograph mMR. The modular type physical phantoms that provide assembly versatility for phantom construction were scanned in a four-channel Body Matrix coil. The MRAC map was generated using the two-point Dixon-based segmentation method for whole-body imaging. The modular phantoms were scanned in compact and non-compact assembly configurations. In addition, the phantoms were scanned repeatedly to generate MRAC maps. The acquired MRAC maps show differently assigned values for void areas. An incorrect assignment of a void area was shown on a locally compact space between phantoms. The assigned MRAC values were distorted using a wide field-of-view (FOV). The MRAC values also differed after repeated scans. However, the erroneous MRAC values appeared outside of phantom, except for a large FOV. The MRAC map of the phantom was affected by phantom configuration and the number of scans. A quantitative study using a phantom in a PET/MRI system should be performed after evaluation of the MRAC map characteristics.

• 대한방사선기술학회지:방사선기술과학
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• 제44권1호
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• pp.31-37
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• 2021

This study aim of quantitative assessment of Noise Power Spectrum(NPS) and image characteristics of by acquired the optimal image for noise characteristics and quality assurance by using magnetic resonance imaging(MRI). MRI device was (MAGNETOM Vida 3.0T MRI; Siemense healthcare system; Germany) used and the head/neck shim MR receive coil were 20 channels coil and a diameter 200 mm hemisphere phantom. Frequency signal could be acquired the K-space trajectory image and white image for NPS. The T2 image highest quantitatively value for NPS finding of showed the best value of 0.026 based on the T2 frequency of 1.0 mm-1. The NPS acquired of showed that the T1 CE turbo image was 0.077, the T1 CE Conca2 turbo image was 0.056, T1 turbo image was 0.061, and the T1 Conca2 turbo image was 0.066. The assessment of NPS image characteristics of this study were to that could be used efficiently of the MRI and to present the quantitative evaluation methods and image noise characteristics of 3.0T MRI.

• 비파괴검사학회지
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• 제31권2호
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• pp.174-180
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• 2011

본 연구에서는 초음파원자현미경을 이용하여 비파괴적인 표면탄성이미지 분석과 나노표면에서의 기계적 물성 평가를 연구하였다. 이를 위해 접촉역학 특성에 따른 캔틸레버의 공진주파수 변화를 이론적으로 해석하고 실험적으로 측정하였다. 스프링-질량 모델과 Herzian 이론을 이용하여 계산한 이론적인 접촉공천주파수는 초음파원자현미경 캔틸레버의 실험적인 접촉 공진주파수의 변화와 매우 유사하였다. 결과적으로, 초음파원자현미경의 표면 높이 이미지와 진폭이미지를 성공적으로 얻을 수 있었고 진폭신호를 통하여 시료표면에서의 탄성특성을 정성적으로 평가하였다.

• Investigative Magnetic Resonance Imaging
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• 제14권1호
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• pp.69-73
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• 2010

뇌 지방 색전증은 비록 드물지만, 장골 골절의 잠재적, 치명적 합병증이다. 두부외상이 없이, 초기에는 명료한 의식을 보였으나, 추후 의식저하를 보이는 모든 환자는 뇌 지방 색전증을 염두에 둔 진단적 검사를 받아야한다. 본 증례에서, 자기공명영상 특히 확산-강조 영상이 뇌 지방 색전증의 진단에있어서 최고의 민감도를 보였다. 저자는 이 증례를 통해, 병리생리학적 근거를 바탕으로 한 뇌 지방 색전증의 자기공명영상의 특이점 해석과 치료를 보고하고자 한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.101-106
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• 2011

In the present paper, the phenomena of abnormal noise and vibration due to acoustic resonance of CFBC(Circulating Fluidized Bed Combustion) boiler was presented. The acoustic resonance which occurred in the gas path of CFBC boiler system was caused by coincidence of vortex shedding frequency of tube bank and acoustic natural frequency of duct and hopper. And, the phenomena of beating arose from the interference of two closed resonant waves at 66.4Hz and 70.8Hz. There are two control methods for acoustic resonance in this system. The first method is to change the vortex shedding frequency from the structural alterations on the tube bank. And the second method is to change the acoustic natural frequency of the gas path with the installation of anti-noise baffles. The second one which is relatively easy to apply, was adapted in this study. As a result, the noise and vibration level have been decreased by 41dB and 94% at 66.4Hz, respectively. And the improvement of noise and vibration at 70.8Hz was identified by sensory evaluation.

• Investigative Magnetic Resonance Imaging
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• 제22권4호
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• pp.254-259
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• 2018

Application of magnetic resonance imaging (MRI) for assessment of pulmonary disease has been limited, due to susceptibility to cardiac pulsation, respiratory motion, and inhomogeneity of the magnetic field of the lung. With technical advances of MRI and unmet clinical needs for more accurate diagnosis and assessment of the disease, however, the use of MRI for evaluation of the lung has broadened. Herein, we present a case of pneumonic-type lung adenocarcinoma in a patient with history of anaphylactic shock to iodinated contrast medium, in which MRI played a critical role for targeted lung biopsy and cancer staging. Through this paper, we would like to report potential value of MRI in assessment of lung cancer.