• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.126-130
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• 1997

In the development of the totally implantable artificial heart (TAH), the information of the preload condition is important to ind appropriate condition or the automatic control of the heart. Our TAH configuration consists of two artificial ventricles, and brushless DC motor within actuator. The pressure between ventricles could indicate the preload condition during the TAH operation. If we can measure accurately inspite of the noise induced from TAH and environmental condition. We suggested integrating a feedback loop to remove an unexpected DC drift. NPI 19-series Nova sensor was used which could measure pressure in gas and liquid. This method and sensor enabled us to develop the pressure transducer compact so (that) the systems can be implanted with TAH into patient. This system has been verified in vitro and in vivo test. This results showed that the output waveform of this system was stable irrespective of animal condition.

• 대한기계학회논문집B
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• 제26권1호
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• pp.74-81
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• 2002

Combustion phenomena in a sub-millimeter scale combustor have been investigated. To evaluate scale effect on flame propagation characteristics, a cylindrical combustion chamber with variable depth was built in-house. The combustor was charged with premixed gas of hydrogen and air and ignited electronically. A piezo electric pressure transducer recorded transient pressure after the ignition. Measurements were made at different test conditions specified with chamber depth and initial pressure as parameters. Visual observation was made through a quartz glass window on top side of the combustion chamber using high speed digital video camera. From the pressure data, available work was estimated and compared with energy input required for stable ignition. The preliminary results suggested that the net thermal energy release is sufficient to generate power and enables a combustor of the size in the present study to be used as the energy source of a micro power devices .

• Journal of Welding and Joining
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• 제30권6호
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• pp.36-41
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• 2012

General condensers consist of many tubes supported by tube sheets and support plates to prevent the deflection of the condenser tubes. When a fluid at high pressure and temperature runs over the tubes for the purpose of transferring heat from one medium to another, the tubes vibrate and their surface comes into contact with the support plates. This vibration causes damage to the tubes, such as cracks and wear. We propose an ultrasonic guided wave technique to detect the above problems in the support plate region. In the proposed method, the ultrasonic guided wave mode, L(0,1), is excited using an internal transducer probe from a single position at the end of the tube. In this paper, we present a preliminary experimental verification using a super stainless tube and show that the defects can be discriminated from the support signals in the support region.

• 한국광학회지
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• 제9권4호
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• pp.240-244
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• 1998

공동 광자 감쇠 분광법(cavity ring down spectroscopy, CRDS)은 미량기체의 절대밀도를 측정할 수 있는 고감도 레이저 분광기술이다. 연속발진 레이저(continuous wave laser)를 사용한 새로운 방법의 CRDS 분광기를 구현하였다. 이 장치에서는 PZT(piezoelectric transducer)를 움직여 공동의 길이를 비공명(off-resonance)상태로 빠르게 변화시킴으로써 입사되는 연속발진 레이저 빔을 차단하여 감쇠신호를 발생시킨다. 이 방법으로 570 nm 근처에서 압력이 2700 Pa인 아세틸렌(C2H2)의 overtone 천이에 대한 흡수 분광선을 측정하였으며, 이때 측정할 수 있는 최소 흡수계수는 3$\times$10-9 cm-1정도이다.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.93-100
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• 2016

Since the sodium-cooled fast reactor is operated in a hostile environment due to the use of liquid sodium as its coolant, advanced techniques for in-service inspection are required to periodically verify the integrity of the reactor. This paper presents the development of in-service inspection techniques for Proto-type Generation IV Sodium-cooled Fast Reactor. First, the 10 m long plate-type ultrasonic waveguide sensor has been developed for in-service inspection of reactor internals, and its feasibility was verified through several under-water and under-sodium experiments. Second, the combined inspection system for in-service inspection of ferromagnetic steam generator tubes has been developed. The remote field eddy current testing and magnetic flux leakage testing can be conducted simultaneously by using the developed inspection system, and the detectability was demonstrated through several damage detection experiments. Finally, the electro-magnetic acoustic transducer which can withstand high temperature and be installable in the remote operated vehicle has been developed for in-service inspection of the reactor vessel, and its detectability was investigated through damage detection experiments.

• Clinical Endoscopy
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• 제56권2호
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• pp.229-238
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• 2023

Background/Aims: Shear wave elastography (SWE) is used for liver fibrosis staging based on stiffness measurements. It can be performed using endoscopic ultrasound (EUS) or a transabdominal approach. Transabdominal accuracy can be limited in patients with obesity because of the thick abdomen. Theoretically, EUS-SWE overcomes this limitation by internally assessing the liver. We aimed to define the optimal technique for EUS-SWE for future research and clinical use and compare its accuracy with that of transabdominal SWE. Methods: Benchtop study: A standardized phantom model was used. The compared variables included the region of interest (ROI) size, depth, and orientation and transducer pressure. Porcine study: Phantom models with varying stiffness values were surgically implanted between the hepatic lobes. Results: For EUS-SWE, a larger ROI size of 1.5 cm and a smaller ROI depth of 1 cm demonstrated a significantly higher accuracy. For transabdominal SWE, the ROI size was nonadjustable, and the optimal ROI depth ranged from 2 to 4 cm. The transducer pressure and ROI orientation did not significantly affect the accuracy. There were no significant differences in the accuracy between transabdominal SWE and EUS-SWE in the animal model. The variability among the operators was more pronounced for the higher stiffness values. Small lesion measurements were accurate only when the ROI was entirely situated within the lesion. Conclusions: We defined the optimal viewing windows for EUS-SWE and transabdominal SWE. The accuracy was comparable in the non-obese porcine model. EUS-SWE may have a higher utility for evaluating small lesions than transabdominal SWE.

• 사상체질의학회지
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• 제12권1호
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• pp.216-227
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• 2000

1. 연구목적 태음인(太陰人) 청심연자탕(淸心蓮子湯)은 "동의수세보원(東醫壽世保元)" 태음인병 24처방 중에 기재된 신정방으로 태음인 간조열증(肝燥熱證)에 응용되는 처방이다. 근래에는 뇌졸중을 비롯한 중추신경계통 질환에 많이 사용되고 있다. 이러한 태음인(太陰人) 청심연자탕(心蓮子湯)의 용도를 과학기기를 이용하여 기전을 규명하고자 하였다. 2. 연구방법 백서를 urethane으로 마취시키고 태음인(太陰人) 청심연자탕(淸心蓮子湯)을 투여한 후 Pressure Transducer와 Laser-Doppler flowmetry를 이용하여 백서의 혈압과 국소뇌혈류량을 측정하였으며 이를 구성약물까지 진행하였다. 또한 태음인(太陰人) 청심연자탕(淸心蓮子湯)의 대뇌혈류에 관한 기전 규명을 위하여 propranolol과 methylene blue로 전처치한 후 태음인(太陰人) 청심연자탕(淸心蓮子湯)을 투여하여 이를 분석하였다. 3. 결과 및 결론 태음인(太陰人) 청심연자탕(淸心蓮子湯)의 투여로 혈압의 유의한 변화는 없었으며, 국소뇌혈류량은 유의하게 증가되었다. 구성약물 중 연자육(蓮子肉), 맥문동(麥門冬), 천문동(天門冬), 원지(遠志), 산조인(酸棗仁), 룡안육(龍眼肉), 나복자, 감국(甘菊)은 국소뇌혈류량을 유의하게 증가시켰다. 이 실험으로 태음인(太陰人) 청심연자탕(淸心蓮子湯)의 국소뇌혈류량 증가의 기전은 교감신경 ${\beta}$-수용체와 cyclic GMP의 생성효소인 guanylyl cyclase의 작용과 관련이 있는 것으로 생각된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.245-246
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• 2009

정전용량형 후막 스트레인 게이지(piezocapacitive thick film strain gage)는 세라믹 ($Al_2O_3$)을 주 원료로 하는 지지대(약 5mm)와 다이어프램(약 $300{\mu}m$) 그리고 가드 링으로 구성된다. 전극 판은 도전성 페이스트를 이용하여 지지대와 다이어프램에 형성되었으며 극판 사이에는 유전체 메이스트를 사용하여 스크린 인쇄로 후막을 형성하였다. 극판 사이의 가드 링 두께는 약 $30{\mu}m$정도로 다이어프램의 변위 최대값을 유지시키는 데 필요한 간격이다. 따라서 정전용랑형 후막 스트레인 게이지는 지지대를 중심으로 다이어프램에 압력 (0.5~1.0bar)이 인가될 때 변위를 발생시키면서 커패시터 값이 압력의 크기에 따라 비례 특성을 가지고 변화하는 것을 이용한 것이다. 압력이 없을때 초기값은 35pF~40pF 정도이고 정격압력의 최대치를 인가시켰을 때 약 55pF~55p를 나타내었다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.36-44
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• 2000

The flow at the impeller exit is important to validate engineering design and numerical analysis of pumps. We installed axisymmetric collector instead of the volute casing, so there is no interaction between the impeller and casing. A hot-film probe and a high response pressure transducer are used to investigate the flow at impeller exit and vaneless diffuser region for design and off design flow rate. For a single suction centrifugal pump of low specific speed, the flow field such as velocity, flow angle, and total pressure are measured by traversing the probe across the vaneless diffuser. These data can be used for performance prediction, design, and numerical analysis of pumps.

• 한국기계가공학회지
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• 제10권5호
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• pp.125-130
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• 2011

The characteristics of unsteady combustion were experimentally investigated using confined premixed flames stabilized by a rearward-facing step. The unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillations and it has usually desirable performance such as high load combustion and low pollutant emission. It is known that combustion oscillation is occurred if Rayleigh's criterion is satisfied. The pressure fluctuation and OH-emission fluctuation were measured using pressure transducer and OH optical fiber respectively and then cross-corelation and phase difference were calculated to apply Rayleigh's criterion.