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다층 PZT 초음파 트랜스듀서에 대한 새로운 전송선로형 등가회로의 제안
김무준,하강열,김성부,이종규,Kim, Moo-Joon,Ha, Kang-Lyeol,Kim, Sung-Boo,Lee, Jong-Kyu 한국음향학회 1995 韓國音響學會誌 Vol.14 No.4
높은 결합계수를 가진 압전진동자의 전기단자에 전기적 임피던스를 결합하면 공진주파수가 크게 변화한다. 본 연구에서는 이 현상의 해석을 위하여 전기단자의 부하상태를 고려한 새로운 전송선로형 등가회로를 제안하고, 그 등가회로의 유효성을 실험적으로 확인하였다. 실험에 있어서는 2층구조의 주파수 가변형 PZT 트랜스듀서를 제작, 그 전기단자에 접속시킨 임피던스의 변화에 따른 공진주파수의 변화와 실효감쇠량을 측정하였다. 제작된 트랜스듀서의 공진주파수는 180 KHz~580KHz의 넓은 주파수 대역에서 연속적으로 변화하고, 330KHz~470KHz에서의 실효감쇠량은 7dB이하의 높은 효율을 나타내었는데, 이 결과는 제안한 등가회로에 의한 해석결과와 잘 일치하였다. A resonant frequency of piezoelectric transducer depends remarkably on the electric impedance connected to the vibrator. In this paper, using this effect of frequency controllable two layered PZT ultrasonic transducer is designed and its acoustic characteristics are analyzed by a new transmission model equivalent circuit. The theoretical and the experimental results of the electric impedance effect on the resonant frequency variation were compared and both results showed a good consistency each other. The resonant frequency has been controlled continuously in the wide frequency range of 180kHz~580kHz and the effective attenuations were less than 7dB in the frequency range of 330kHz~470kHz.
비소성 시멘트의 활성황토 치환에 따른 모르타르의 특성 변화
김무준 ( Moo-joon Kim ),문경주 ( Kyoung-ju Mun ),형원길 ( Won-gil Hyung ) 한국폐기물자원순환학회(구 한국폐기물학회) 2020 한국폐기물자원순환학회지 Vol.37 No.2
In construction sectors, activities using cement emit a significant amount of carbon dioxide accounting for approximately 30% of global CO<sub>2</sub> emissions. Therefore, the use of cement in construction sectors needs to be reduced in order to reduce CO<sub>2</sub> emissions. In this regard, herein the properties of non-sintered cement mortar made with ground granulated blast furnace slag, high calcium fly ash, and activated Hwangto were characterized to find proper eco-friendly replacement of cement. Flow test results of non-sintered cement mortar indicated a tendency for water/binder ratio is increased with the rate of adding activated Hwangto. When activated Hwangto was added, flexural and compressive strength was 20% (HFAH-20). Absorption rates was also increased with the addition of activated Hwangto. The neutralization test showed that the nonsintered cement mortar made with activated Hwangto is responded. X-ray diffraction analysis showed that as activated Hwangto is added, stratlingite was increased but Ca(OH)<sub>2</sub> was decreased. Through scanning electron microscope analysis, a small amount of ettringite and calcium-silicate-hydrate gels was found, but no plate-like Ca(OH)<sub>2</sub> were observed.
플랜트 시설물 안전관리를 위한 Pipe Insulation의 화재안전성능 기준 현황 연구
김무준(Moo Joon Kim),신이철(Yi Chul Shin),박수영(Soo Young Park),이길용(Gil Yong Lee),여한승(Han Seung Yeo) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
This study aims to investigate and analyze the current status of the fire safety performance standards for pipe insulation for plant facility safety management. According to statistics from the National Fire Agency, the number of fires has tended to decrease in the past 10 years (2011-2020), but deaths and property damage caused by fires have been on the rise. In addition, plants that use high-pressure gas have a high fire strength and a fast spread in the event of a fire. As a result of examining the current status of domestic and foreign standards for pipe insulation materials, the flame retardancy performance of fire-fighting pipe insulation materials only suggests a certain performance (oxygen index test ≥ 28, horizontal combustion test HF-1 grade). On the other hand, Sunström (2002) presented the International Standard for Reaction-to-Fire Tests - Small room test for pipe insulation product systems: 2008) for the real-scale fire safety evaluation method for piping insulation based on EN 13823 (SBI) and ISO 9705. As a result of the study, it is judged that it is difficult to prevent the spread of fire with the flame retardant performance of domestic pipe insulation. Considering the current piping thermal insulation market, realistic flame retardant performance standards are required, and it is judged that test standards that can consider field applicability through actual-scale tests such as ISO 20632 are needed.
플랜트 시설물 안전관리를 위한 Pipe Insulation의 화재안전성능 기준 현황 연구
김무준(Moo Joon Kim),신이철(Yi Chul Shin),박수영(Soo Young Park),이길용(Gil Yong Lee),여한승(Han Seung Yeo) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
This study aims to investigate and analyze the current status of the fire safety performance standards for pipe insulation for plant facility safety management. According to statistics from the National Fire Agency, the number of fires has tended to decrease in the past 10 years (2011-2020), but deaths and property damage caused by fires have been on the rise. In addition, plants that use high-pressure gas have a high fire strength and a fast spread in the event of a fire. As a result of examining the current status of domestic and foreign standards for pipe insulation materials, the flame retardancy performance of fire-fighting pipe insulation materials only suggests a certain performance (oxygen index test ≥ 28, horizontal combustion test HF-1 grade). On the other hand, Sunström (2002) presented the International Standard for Reaction-to-Fire Tests - Small room test for pipe insulation product systems: 2008) for the real-scale fire safety evaluation method for piping insulation based on EN 13823 (SBI) and ISO 9705. As a result of the study, it is judged that it is difficult to prevent the spread of fire with the flame retardant performance of domestic pipe insulation. Considering the current piping thermal insulation market, realistic flame retardant performance standards are required, and it is judged that test standards that can consider field applicability through actual-scale tests such as ISO 20632 are needed.
플랜트 시설물 안전관리를 위한 Pipe Insulation의 화재안전성능 기준 현황 연구
김무준(Moo Joon Kim),신이철(Yi Chul Shin),박수영(Soo Young Park),이길용(Gil Yong Lee),여한승(Han Seung Yeo) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
This study aims to investigate and analyze the current status of the fire safety performance standards for pipe insulation for plant facility safety management. According to statistics from the National Fire Agency, the number of fires has tended to decrease in the past 10 years (2011-2020), but deaths and property damage caused by fires have been on the rise. In addition, plants that use high-pressure gas have a high fire strength and a fast spread in the event of a fire. As a result of examining the current status of domestic and foreign standards for pipe insulation materials, the flame retardancy performance of fire-fighting pipe insulation materials only suggests a certain performance (oxygen index test ≥ 28, horizontal combustion test HF-1 grade). On the other hand, Sunström (2002) presented the International Standard for Reaction-to-Fire Tests - Small room test for pipe insulation product systems: 2008) for the real-scale fire safety evaluation method for piping insulation based on EN 13823 (SBI) and ISO 9705. As a result of the study, it is judged that it is difficult to prevent the spread of fire with the flame retardant performance of domestic pipe insulation. Considering the current piping thermal insulation market, realistic flame retardant performance standards are required, and it is judged that test standards that can consider field applicability through actual-scale tests such as ISO 20632 are needed.
Active Vibration Control Method Using Frequency Controllable Piezoelectric Transducer
김정순,김무준,하강렬,강성학,Kim, Jung-Soon,Kim, Moo-Joon,Ha, Kang-Lyeol,Kang, Sung-Hak The Acoustical Society of Korea 2007 韓國音響學會誌 Vol.26 No.e1
Hydraulic actuator and electro-magnetic liner actuator have been used as typical active vibration control methods. However these methods have many kinds of disadvantages such as causing space limit, difficult maintenance, complicate structures, etc. The purpose of this paper was to study on the possibility of active vibration control using piezoelectric transducer. Piezoelectric transducer generated a vibration and GIC (General Impedance Converter) amplifier was adopted to give adjustable vibration signal to transducer and high amplitude of vibration. Resonance frequency of piezoelectric transducer was controlled by GIC amplifier and higher amplitude of vibration was achieved. Finally active vibration control using piezoelectric transducer was performed.
하강열,김무준,이종규,김성부,신발헌현,Ha, Kang-Lyeol,Kim, Moo-Joon,Lee, Jong-Kyu,Kim, Sung-Boo,Noriyoshi, Chubachi 한국음향학회 1995 韓國音響學會誌 Vol.14 No.6
초음파펄스의 주파수해석에 의하여 재료의 음속과 감쇠계수 및 복소모듈러스를 동시에 측정하는 시스템을 구축하고 그 특성을 평가하였다. 이 시스템은 초음파현미경의 기계구동부와 공진주파수 85MHz의 ZnO 평면 트랜스듀서에 의해 구성되며, 음속은 시료의 표면과 저면에서 반사되어온 두개의 펄스파가 동시에 포함되도록 게이트한 후 파워스펙트럼을 구하였을 때 생기는 주파수영역에서의 극대점(또는 극소점)간의 간격으로부터, 감쇠계수는 그 두 펄스파의 각각에 대한 파워스펙트럼준위와 표준시료 표면으로 부터의 반사파의 파워스펙트럼준위로부터 구하여진다. 구축된 시스템을 용융석영, 폴리에스텔막등의 재료에 적용한 결과 정도 높은 계측이 가능함을 알았다. A system for measurement of ultrasonic velocity, attenuation and complex modulus of materials by using the spectral analysis method of pulses has been constructed and its performances are estimated. The system has a mechanical scanning part of an acoustic microscope with a ZnO plane wave transducer of the resonant frequency of 85MHz. Ultrasonic velocity has been obtained by the intervals of maxima (or minima) on the power spectrum of a pulse train reflected from the surface and bottom of a specimen, and attenuation has been obtained by the power spectra of three pulses reflected from the surface and the bottom of a specimen and the surface of a standard specimen. The measured results for materials such as fused quartz, polyester show that the system has very high accuracy.