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초음파 유량계에 사용되는 초음파 진동자 특성향상에 관한 연구
현병국(Byung-Gook Hyun),황상윤(Shang-Yoon Hwang),안용관(Yong-Kwan Ahn),박성하(Sung-Ha Park) 한국유체기계학회 2001 유체기계 연구개발 발표회 논문집 Vol.- No.-
For the piezoelectric vibrator, PZT, in a general transmit-receive sensor using the ultrasonic flowmeter, the characteristics of frequency response relating to the backing materials were analyzed with the Mason equivalent circuit for design, and the sensitivity of fabricated transducer relating to the matching materials was measured and discussed. The results those were measured in water for the transmit-receive characteristics of each transducer can be applied to the flowmeter sensor.
2차원 배열 수중청음기를 이용한 생체조직에서의 초음파 음장 전파특성 측정
하강열,김무준,현병국,채민구,Xiu-Fen Gong 한국음향학회 2001 韓國音響學會誌 Vol.20 No.5
Because the biological tissue with inhomogeneous acoustic properties does not keep a particular shape, the measurement of propagation characteristics of ultrasonic fields by the conventional scanning method with a miniature hydrophone is difficult. In this study, a two-dimensional may hydrophone was fabricated using the PVDF (Polyvinylidene fluoride) piezo-electric film and a ultrasonic field measurement system with it was established. For the acoustic field produced by a circular plan transducer with center frequency of 2.25㎒ and 13㎜ in diameter, it was possible to make a fairly accurate field measurement using the hydrophone system. The attenuation coefficients at 2.25 ㎒ for biological tissues were 0.7∼1.3 dB/cm(average; 1.0 dB/cm) in bovine liver, 1.0∼1.8 dB/cm (average; 1.6 dB/cm) in pig liver, 0.9∼2,9 dB/cm(average: 2.1 dB/cm) in bovine muscles, 1.7∼3.3 dB/cm (average; 2.5 dB/cm) in pig muscles. 음향특성이 균일하지 않는 생체조직은 특정의 형태 유지가 어렵기 때문에 종래의 극소형 수중청음기의 스캐닝 방법에 의한 초음파 음장 전파특성 측정이 곤란하다. 본 연구에서는 PVDF (Polyvinylidene fluoride) 압전막을 사용하여 2차원 배열 수중청음기를 제작하고, 그것에 의한 음장 측정 시스템을 구축한 후, 생체조직에 적용하였다. 중심주파수 2.25 ㎒이고 직경이 13㎜인 원형평면 트랜스듀서에 의한 실험 결과, 구축한 시스템에 의해 비교적 정밀한 음장 측정이 가능한 것을 알았으며, 그 주파수에 대해 소와 돼지의 간에서는 각각 0.7∼l.3dB/cm (평균; 1.0 dB/cm), 1.0∼l.8 dB/cm (평균; 1.6 dB/cm), 근육에서는 각각 0.9∼2.9 dB/cm (평균; 2.1dB/cm), 1.7∼3.3 dB/cm (평균: 2.5 dB/cm)의 값을 갖는 감쇠계수의 공간적 분포를 측정할 수 있었다.
Enhanced cell growth inhibition by thiacremonone in paclitaxel-treated lung cancer cells
반정옥,황철주,박미희,황인국,정헌상,이희범,현병국,김지영,윤해석,함영완,윤도영,한상배,송민종,홍진태 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.7
Activation of nuclear factor kappa-B (NF-jB) is implicated in drug resistant of lung cancer cells. Our previous data showed that thiacremonone inhibited activation of NF-jB. In the present study, we investigated whether thiacremonone enhanced susceptibility oflungcancercellstoa common anti-cancer drug paclitaxel by further inhibition of NF-jB. Thus, we used the threefold lower doses of IC50 values (50 lg/ml thiacremonone and 2.5 nM paclitaxel). We found that combination treatment with thiacremonone and paclitaxel was more susceptible (combination index; 0.40inNCI-H460cellsand0.46inA549cells)incellgrowth inhibition of two types of lung cancer cell lines compared to a single agent treatment. Consistent with the combination effect on cancer cell growth inhibition, the combination treatment further induced apoptotic cell death and arrested the cancer cells in G2/M phase accompanied with a much lowerexpressionofcdc2andcyclinB1,andinhibitedcolony formation. Much more inactivation of NF-jB and greater expression of NF-jB target apoptosis regulated genes such as caspase-8 and PARPs were found by the combination treatment. Molecular model and pull down assay as well as MALDI-TOF analysis demonstrated that thiacremonone directly binds to p50. These data indicated that thiacremonone leads to increased apoptotic cell death in lung cancer cell lines through greater inhibition of NF-jB by the combination treatment with paclitaxel.
물리센서 - 2 차원 배열 수증청음기의 제작과 초음파 음장 측정에의 응용
하강열(Kang Lyeol Ha),김무준(Moo Joon Kim),강갑중(Gab Joong Kang),현병국(Byung Gook Hyun),채민구(Min Ku Chae),금야 화언(Gazuhiko Imano) 한국센서학회 2001 센서학회지 Vol.10 No.5
N/A Two-dimensional array hydrophones with 8 x 8 elements were designed and fabricated using the PVDF(Polyvinylidene fluoride) piezoelectric film, and the method and system for ultrasonic field measurement in several MHz ∼ tens of MHz band using the hydrophones was established. The characteristics of frequency response relating to the backing materials were analyzed with the Mason equivalent circuit for design, and the accuracy of ultrasonic field measurement relating to the sizes and kerfs of piezoelectric elements was discussed. Good results of the measurement of ultrasonic field formed by a circular plane transducer of 2.25MHz in water were obtained by the system with the array hydrophones.