• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 추계학술대회 논문집
• /
• pp.200-203
• /
• 2000

The application of the ultrasonic nozzle has been extended because it is possible atomization of liquid material. In this study, the characteristics of the ultrasonic nozzle and ceramic oscillator were investigated. The oscillator for the ultrasonic nozzle were made piezoelectric ceramic of Pb[($Sb_{1/2}$ $Nb_{1/2}$)$_{0.035}$-($Mn_{1/3}$$Nb_{2/3}$)$_{0.065}$-($Zr_{0.49}$$Ti_{0.51}$)$_{0.90}$]$O_3$. The electromechanical coupling factor($k_p$) and mechanical quality factor(Qm) showed the values of 0.555, 1, 214 respectively when the Zr/Ti ratio was 49/51. Moreover, this oscillator will have the temperature stability because it's curie temperature is 322[$^{\circ}C$]. The driving current of ultrasonic nozzle showed the value of 80[mA] when the driving time was lO[min.]. Also, The surface temperature of ceramic oscillator showed 80[$^{\circ}C$] at driving time lO[min.] We knew that the ultrasonic nozzle had stabile driving above 10[min.].

• 한국정밀공학회지
• /
• 제17권11호
• /
• pp.206-212
• /
• 2000

This paper presents a hybrid actuator scheme to actively control the end-point position and vibration of a two-link flexible robot arm. Control scheme consists of four different actuators; two servo-motors at the hubs and two piezoceramics bonded to the surfaces of the flexible links. Two sliding hyperplanes are designed for two servo-motors which have time varying parameters to maintain control performance in any configuration. The surface gradients of the hyperplanes are determined by pole assignment technique to guarantee the stability on the hyperplanes themselves. During the motion, undesirable oscillations caused by the torques based on the rigid link dynamics are actively suppressed by applying feedback control voltages to the piezoceramic actuators. Consequently, desired tip motion is achieved. In order to demonstrate the effectiveness of the proposed methodology, experiments are performed for the regulating and tracking control problems.

• Steel and Composite Structures
• /
• 제31권4호
• /
• pp.341-359
• /
• 2019

Non-monolithic concrete structural connections are commonly used both in new constructions and retrofitted structures where anchors are used for connections. Often, flaws are present in anchor system due to poor workmanship and deterioration; and methods available to check the quality of the composite system afterward are very limited. In case of presence of flaw, load transfer mechanism inside the anchor system is severely disturbed, and the load carrying capacity drops drastically. This raises the question of safety of the entire structural system. The present study proposes a wave propagation technique to assess the integrity of the anchor system. A chemical anchor (embedded in concrete) composite system comprising of three materials viz., steel (anchor), polymer (adhesive) and concrete (base) is considered for carrying out the wave propagation studies. Piezoelectric transducers (PZTs) affixed to the anchor head is used for actuation and the PZTs affixed to the surrounding concrete surface of the concrete-anchor system are used for sensing the propagated wave through the anchor interface to concrete. Experimentally validated finite element model is used to investigate three types of composite chemical anchor systems. Studies on the influence of geometry, material properties of the medium and their distribution, and the flaw types on the wave signals are carried out. Temporal energy of through time domain differentiation is found as a promising technique for identifying the flaws in the multi-layered composite system. The present study shows a unique procedure for monitoring of inaccessible but crucial locations of structures by using wave signals without baseline information.

• Smart Structures and Systems
• /
• 제28권6호
• /
• pp.761-777
• /
• 2021

This study presents a numerical investigation on the sensitivity of electromechanical (EM) impedance responses to inner damaged concrete of a prestressed anchorage zone. Firstly, the Ottosen yield criterion is selected to simulate the plasticity behavior of the concrete anchorage zone under the compressive loading. Secondly, several overloading cases are selected to analyze inner damage formations in the concrete of the anchorage zone. Using a finite element (FE) model of the anchorage zone, the relationship between applied forces and stresses is analyzed to illustrate inner plasticity regions in concrete induced by the overloading. Thirdly, EM impedance responses of surface-mounted PZT (lead-zirconate-titanate) sensors are numerically acquired before and after concrete damage occurrence in the anchorage zone. The variation of impedance responses is estimated using the RMSD (root-mean-square-deviation) damage metric to quantify the sensitivity of the signals to inner damaged concrete. Lastly, a novel PZT skin, which can measure impedance signatures in predetermined frequency ranges, is designed for the anchorage zone to sensitively monitor the EM impedance signals of the inner damaged concrete. The feasibility of the proposed method is numerically evaluated for a series of damage cases of the anchorage zone. The results reveal that the proposed impedance-based method is promising for monitoring inner damaged concrete in anchorage zones.

• 한국음향학회지
• /
• 제9권4호
• /
• pp.18-32
• /
• 1990

최근 신호 처리 기기와 센서로서 각광을 받고 있는 SAW Device 는 때론 목적에 따라 수중에서 사용해야 할 때가 있다. 그러나 유체내의 고체 표면을 전파하는 표면파의 경우, 유체내로의 에너지 손실로 인해 설계상에 많은 어려움을 주고 있다. 따라서 본 연구에서는 이러한 어려움을 극복할 수 있는 최적 설계법으로서, 컴퓨터 모형해석을 통해 수중에서 압전물질에 의한 표면파의 최대 발진 효율, 최소 전파 감쇄율, 그리고 pure mode 전파를 이룰 수 있는 SAW Device 의 최적 geometry, 즉 초적 압전 결정 평면, 표면과 전파 방향, 그리고 무차원 전파 계수 들을 구하였다. 본 논문에서는 표면파가 전파하는 고체 재료로서 PZT와 PVDF 적층, 그리고 쇠 하부층을 사용하였으나, 이 설계법은 임의의 유체층과 고체층의 조합에도 적용할 수 있다. 동일한 기술은 수중음향 계측기, antifouling, 그리고 산업 및 의료 분야 등에 쓰이는 센서와 발진기의 설계에도 바로 응용할 수 있다.

• 마이크로전자및패키징학회지
• /
• 제12권3호
• /
• pp.267-274
• /
• 2005

This paper presents the fabrication of surface acoustic wave (SAW)-based pressure sensor for long-term stable mechanical compression force measurement. SAW pressure sensor has many attractive features for practical pressure measurement: no battery requirement, wireless pressure detection especially at hazardous environments, and easy other functionality integrations such as temperature, humidity, and RFID. A $41^{\circ}$ YX $LiNbO_3$ piezoelectric substrate was used because of its high SAW propagation velocity and large values of electromechanical coupling factors $K^2$. A silicon substrate with $\~200{\mu}m$ deep cavity was bonded to the diaphragm with epoxy, in which gold was covered all over the inner cavity in order to confine electromagnetic energy inside the sensor, and provide good isolation of the device from its environment. The reflection coefficient $S_{11}$ was measured using network analyzer. High S/N ratio, sharp reflected peaks, and clear separation between the peaks were observed. As a mechanical compression force was applied to the diaphragm from top with extremely sharp object, the diaphragm was bended, resulting in the phase shifts of the reflected peaks. The phase shifts were modulated depending on the amount of applied mechanical compression force. The measured $S_{11}$ results showed a good agreement with simulated results obtained from equivalent admittance circuit modeling.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권12호
• /
• pp.5115-5118
• /
• 2015

Background: The $p16^{INK4a}$ is a protein that expressed in Liquid-based cervical cytology specimens and has been proved link to cervical cancer. The $p16^{INK4a}$ could be detection by piezoelectric immunosensor and the immobilization of the $p16^{INK4a}$ antibody influence the sensitivity of the piezoelectric immunosensor. Materials and Methods: $5{\mu}L$ mouse polyclonal antibody against $p16^{INK4a}$ was bound onto the surface of immonosensor through two methods. (directly immobilized method; protein A method). Absorb of the $p16^{INK4a}$ antibody on the surface of immonosensor caused a shift in the resonant frequency of the immunosensor and The frequency changes recorded showed a better reproducibility. The activity of the immobilization antibody with the directly method and protein A method was tested with $p16^{INK4a}$ antigen. Results: The resonant frequency for different antibody immobilization methods were different, and the sensitivity for $p16^{INK4a}$ detection also different. Conclusions: The protein A method was found to be much more better than the directly method for the immobilization of the p16INK4A antibody on the gold electrode of the quartz crystal for cervical lesion detection. The Protein A method created more reproducible and stable immobilization antibody layers with p16INK4A antigen.

• 한국식품과학회지
• /
• 제31권1호
• /
• pp.1-6
• /
• 1999

Salmonella spp.의 신속한 검출을 위하여 발진모듈, 수정결정 진동측정기, 박막형태의 수정결정으로 이루어진 압전류적(piezoelectric, PZ) 항체센서 시스템을 구성하였다. 수정결정의 금전극 표면에 Salmonella 구조 항원(common structural antigen)에 대한 항체를 protein A를 사용하여 고정화하고, 항체가 고정화된 수정결정과 미생물간의 결합반응에 의한 질량증가로 나타나는 진동수의 감소량을 측정하였다. PZ 항체센서는 $35^{\circ}C$, pH 7.2의 0.1M 인산 완충용액에서 Salmonella균에 대하여 가장 높은 감응도를 나타내었다. PZ 항체센서의 반응은 Salmonella균에 대하여 매우 선택적이었고 polystyrene bead 첨가시 센서의 감응도가 크게 증가하였다. Salmonella균의 농도가 $10^5{\sim}10^6\;CFU/mL$의 범위 내에 있을 때 쌍대수좌표에서 직선구간의 검량선을 얻을 수 있었고, Salmonella 검출에 소요되는 시간은 50분이내 이었다.

• 대한기계학회논문집
• /
• 제8권6호
• /
• pp.591-598
• /
• 1984

본 논문에서는 고체상호간 미끄름접촉에 의해 발생하는 진동과 소음의 특성을 조사하기 위해서 실험과 이론해석을 행하였다. 미끄름접촉과 관련된 소음에는 brake squeal 혹은 wheel screech등과 같이 stick-slip 형태의 동적 불안정 상태와 관련이 있는 squeal noise와, 겉보기로 동적 안정 상태에 있으나 미끄름접촉면간에 내재하는 미끄름접촉 고유의 불규칙한 동특성에 기인하여 발생하는 rubbing noise가 있다. 본 연구의 대상은 보다 기본적인 형태인 후자에 한한다.

• Journal of the Optical Society of Korea
• /
• 제13권2호
• /
• pp.245-250
• /
• 2009

We propose a digital holographic interference analysis method based on a 2-frame phase-shifting technique for measuring an optical mirror surface. The technique using 2-frame phase-shifting digital interferometry is more efficient than multi-frame phase-shifting techniques because the 2-frame method has the advantage of a reduced number of interferograms, and then takes less time to acquire the wanted topography information from interferograms. In this measurement system, 2-frame phase-shifting digital interferograms are acquired by moving the reference flat mirror surface, which is attached to a piezoelectric transducer, with phase step of 0 or $\pi$/2 in the reference beam path. The measurements are recorded on a CCD detector. The optical interferometry is designed on the basis of polarization characteristics of a polarizing beam splitter. Therefore the noise from outside turbulence can be decreased. The proposed 2-frame algorithm uses the relative phase difference of the neighbor pixels. The experiment has been carried out on an optical mirror which flatness is less than $\lambda$/4. The measurement of the optical mirror surface topography using 2-frame phase-shifting interferometry shows that the peak-to-peak value is calculated to be about $0.1779{\mu}m$, the root-mean-square value is about $0.034{\mu}m$. Thus, the proposed method is expected to be used in nondestructive testing of optical components.