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시간-주파수 통합 해석법을 이용한 유도초음파 모드 분석 알고리즘 도출
이영호,강철식,정창호 충남대학교 산업기술연구소 2006 산업기술연구논문집 Vol.21 No.1
Ultrasound testing as a nondestructive tool has become quite popular and effective inflaw detection and material characterization. Most ultrasonic systems utilize transducers which generate longitudinal or shear waves. However, in those situations involving inspection of sheet or tubular materials, an alternate inspection method utilizingultrasonic guided waves may be more suitable. Unlike longitudinal wave or shear waves, many ultrasonic guided wave modes can exist in a particular component. Each of these modes has a particular wave structure. Wave structure describes the distribution ofparticle motion through the thickness of the tube. And various Joint Time-Frequency Analysis(JTFA) methodology were developed and compared for mode identification tool for received ultrasonic guided wave signal. From the this study, D-STFT was the optimal Joint-Time Frequency Analysis algorithm for ultrasonic guided wave ultrasonic mode identification tool.
Transcranial Doppler Ultrasonography(TCD)의 참고치와 변화 요인들과의 연관성
정종안,조국령,김남욱,강철식,전상윤,홍석,Jung, Jong-An,Cho, Gook-Ryung,Kim, Nam-Uk,Kang, Chul-Sik,Jeon, Sang-Yun,Hong, Seok 대한한방내과학회 2007 大韓韓方內科學會誌 Vol.28 No.4
Objective : We present reference values of flow velocities of intracranial and extracranial cerebral arteries and relation with change factor. Method : We checked transcranial Doppler ultrasonography on mean velocity, systolic velocity, pulsatility index, and resistance index of 252 patients. We also compared differences of change factor. Result : The result showed a difference by sex and age and relevance between vessels besides mean velocity of vessels related with past history and social history. Conclusion : According to the above results, females showed higher velocity of all vessels. With advancing age, subjects showed reduction in velocity and increase in pulsatility index and resistance index. Anterior cerebral, middle cerebral, and posterior cerebral artery increased in proportion to velocity of internal carotid artery and basilar artery. Vessel velocity correlated with diabetes mellitus, hypertension and hyperlipidemia.