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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.
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.
비소성 시멘트의 활성황토 치환에 따른 모르타르의 특성 변화
김무준 ( Moo-joon Kim ),문경주 ( Kyoung-ju Mun ),형원길 ( Won-gil Hyung ) 한국폐기물자원순환학회 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.
압전 배열 트랜스듀서의 진동 요소간 kerf 충진 매질에 따른 특성변화의 실험적 고찰
김정순,김무준,하강렬,Kim, Jung-Soon,Kim, Moo-Joon,Ha, Kang-Lyeol 한국음향학회 2008 韓國音響學會誌 Vol.27 No.5
의료용 초음파 프로브나 압전복합재료 트랜스듀서 등에 있어서는 배열된 압전세라믹 요소간의 공간, 즉 kerf에 주로 폴리머계열의 물질을 충진하고 있다. 이 경우 압전 요소의 횡방향 진동모드의 경계조건이 바뀌어 실제 사용되는 종방향 진동모드의 공진 주파수에도 영향을 미치게 된다. 본 연구에서는 kerf충진 매질에 따른 공진주파수의 변화를 실험적으로 고찰하기 위하여 크기가 $14mm{\times}0.22mm{\times}0.44mm$인 PZT 압전요소의 선형배열에 의한 초음파 트랜스듀서를 제작하고, kerf충진 매질이 없는 경우와 특성이 다른 두 종류의 에폭시로 충진한 경우 각각에 대한 측정을 행하였다. 그 결과 kerf충진 매질에 따른 종방향 공진주파수의 천이 경향이 이론해석 결과와 유사함을 확인하였다. The kerfs between arrayed piezoelectric elements in a medical ultrasonic transducer or a piezoelectric composite transducer are generally filled by polymeric materials. The boundary condition of the elements for lateral mode vibration is changed according to the kerf-filling materials, so that the resonance frequency for longitudinal mode of the transducer is also varied. In this study, to investigate the resonance frequency variation for an arrayed transducer experimentally, the piezoelectric vibration elements of $14mm{\times}0.22mm{\times}0.44mm$ were fabricated and those were linearly arrayed. And, the resonance frequencies were measured for three cases of kerf-filling condition, non-filling and two different kinds of epoxy filling. Conclusively, it is confirmed that the resonant frequency variation shows the similar tendency with the theoretical one for the longitudinal mode.
LiTaO<sub>3</sub> 단결정을 사용한 압전변압기의 개발
황성필,김무준,하강열,강갑중,Hwang, Sung-Phil,Kim, Moo-Joon,Ha, Kang-Lyeol,Kang, Gab-Joong 한국센서학회 2002 센서학회지 Vol.11 No.3
본 연구에서는 온도에 따른 압전특성이 매우 안정적인 $LiTaO_3$ ($x-112^{\circ}$ y) 단결정을 이용하여 압전변압기를 제작하고 그 특성을 분석하였다. 제작시 $LiTaO_3$ 단결정의 변환효율이 낮은 단점을 보완하기 위해 Lame'-mode를 이용하여 길이와 폭의 비가 2:1인 압전변압기를 제작하고 PSpice를 이용하여 진동 모드 해석, 입력전압에 따른 출력전압특성 및 진동속도특성을 분석하였다. 제작한 압전변압기는 길이방향의 제 2차 고조파 주파수와 폭방향의 기본공진주파수가 결합된 290.83[kHz]에서 입력전압에 대한 최대출력전압이 나타났으며, 약 10배 정도의 승압비를 얻을 수 있었다. The single crystal of $LiTaO_3$ ($x-112^{\circ}$ y) has very stable thermal characteristics in a piezoelectric transformer. In this paper, a piezoelectric transformer made of the crystal is newly designed and its operating characteristics are analyzed. The length of the transformer is determined as twice as its width for Lame'-mode because the single crystal of $LiTaO_3$ has low electro-acoustic efficiency. The electric and vibrational characteristics of the transformer is simulated by the PSpice program, and its results are compared to experimental ones. As the results, the ratio of output voltage to input shows large than 10 at 290.83[kHz], which is the frequency coupled the 2nd harmonic for length and the fundamental for width of the Lame'-mode transformer.