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안봉영(Bongyoung Ahn),이승석(Seung Seok Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Plastic anisotropy is one of important factors which determine the drawability of a<br/> steel sheet. It has been mainly measured by mechanical tensile test. From the<br/> ultrasonic velocities propagating along the relative directions to the rolling direction,<br/> CODF (crystallite orientation distribution function) can be measured and ODC's<br/> (orientation distribution coefficients) has some correlations with the plastic anisotropy.<br/> In this study the correlations between the plastic anisotropy and ODC's of the cold<br/> rolled steel sheet were measured. From the results of ultrasonic velocity measurements<br/> the average normal anisotropy, r and the average planar anisotropy, Δr could be<br/> predicted within the accuracy of ±0.082 and ±0.096, respectively. Acoustic resonance<br/> method was applied to measure the ultrasonic velocities and EMAT's were used for<br/> generating and detecting the ultrasonic waves.
도일,임현균,안봉영,지영준,이종실,오재훈,Doh, Il,Lim, Hyun Kyoon,Ahn, Bongyoung,Chee, Youngjoon,Lee, Jongshill,OH, Jae Hoon 대한의용생체공학회 2017 의공학회지 Vol.38 No.3
Blood pressure is one of the important vital signs for monitoring the medical condition of a patient. Automated NIBP(non-invasive blood pressure) monitoring devices calculate systolic and diastolic blood pressures from the oscillation in cuff pressure caused by a pulsation of an artery. To validate the NIBP devices, we developed a simulator to supply the oscillometric waveforms obtained from human subjects. The simulator provided pressure pulses to device-under-test and device readings were compared to the auscultatory references. Fully automated simulation system including OCR(optical character recognition) were developed and used for NIBP monitoring devices. The validation results using the simulator agreed well with previous clinical validation. More validation studies using the standardized oscillometric waveforms would be required for the replacement of clinical trials to validate a new automated NIBP monitoring device.
자기센서에 의한 강재 케이블 장력측정에서 온도특성에 대한 연구
박해원 ( Haewon Park ),안봉영 ( Bongyoung Ahn ),이승석 ( Seungseok Lee ),박정학 ( Jeonghak Park ) 한국구조물진단유지관리공학회 2008 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.12 No.1
교량 지지용으로 사용되는 강재 케이블에 대한 장력측정은 교량의 안전관리에 중요한 측정항목이다. 현재 케이블에 걸린 장력을 주로 진동법으로 장력을 측정하고 있으나 측정 결과가 아직 만족스럽지 못한 상태이다. 또한 선진국에서는 자기적 방식으로 장력측정 방법을 연구하여 이에 대해 여러 가지 결과물을 제공하고 있다. 이에 우리 연구원에서도 자기적 방식에 의한 케이블 장력측정 방법을 연구하고 있으며 이에 대해 이미 논문지에 발표하였으며 자기적 장력측정 시 케이블이 온도에 따라 출력 특성이 크게 변하고 있다. 따라서 재현성이나 정밀도를 높이기 위해서는 강재 케이블의 온도에 따른 정확한 특성식을 산출하고 적용해야 한다. 따라서 금번 논문에서는 강재 케이블의 온도 특성에 대해 시험한 결과를 분석하고 평가하고자 한다. The tension measurement of steel cables that are used to support bridges is a critical element in terms of bridge safety. Today, cable tension at bridge is measured using the vibration method. However, the measurement results have yet been satisfactory. Further, many developed countries have suggested various outcomes of tension measurement through studies on the magnetic method. Our research institute is also studying the cable tensions measurement method using the magnetic sensor and has already published the findings so far as we were able to deduct that the output properties vary greatly according to the temperature of the cable when measuring its tension. Consequently, in order to improve the reproducibility or and precision, we must compute and apply exact coefficients according to steel cable temperatures. Thus, in this study, we intend to analyze and evaluate the results of the test conducted on the temperature properties of steel cables.
김기복(Ki-Bok Kim),안봉영(Bongyoung Ahn),박해원(Haewon Park),김영주(Young-ju Kim),이승석(Seung-Seok Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.8
In this study, the capacitive micromachined ultrasonic transducer (cMUT) was developed. Theoretical analysis and finite element analysis of the behavior of membrane (such as resonance frequency, membrane deflection, collapse deflection and collapse voltage) of the cMUT were performed. The design parameters of the cMUT were estimated and are the dimension and thickness of membrane, thickness of sacrificial layer, thickness and size of electrode, size of active element and so on. With the micro-fabrication process, the cMUT was fabricated on the silicon wafer. To measure the membrane displacement of cMUT, the Michelson phase modulation fiber interferometer was constructed. The measured membrane displacement was good agreed with the result of finite element analysis. To estimate the ultrasonic wave generated by the cMUT, the ultrasonic transceiver system was constructed. The developed cMUT shows a good performance and hence will be widely used to the filed of non-contact ultrasonic application.
자기변형 SH 파 트랜스듀서 모듈을 이용한 배관 점진 감육 진단
조승현(Seung Hyun Cho),박재하(Jae Ha Park),권휴상(Hyu-sang Kwon),안봉영(Bongyoung Ahn),이승석(Seung Seok Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Inspection and monitoring of pipe wall thinning is one of severe problems on structural nondestructive evaluation in nuclear power plants. Even though the guided wave technique shows much possibility for long-range inspection, the gradual thickness variation of a pipe resulted from FAC (Flow Accelerated Corrosion) is not easy to detect due to the small reflection coefficient at the defect. In this work, a method to evaluate gradual wall thinning of a pipe is proposed with a magnetostrictive transducer module. The transducer module is designed to generate and detect multiple modes of SH guided waves. Based on the variation of the dispersion, that is, the propagation characteristics of SH waves, the wall thinning can be detected. Some experiments on artificial wall thinned plates and pipe were conducted. Consequently, the results confirm the feasible performance of the present method with the magnetostrictive transducer module.