• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.372-375
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• 2003

MCA deflection control is a important technology for the development of MEMS applications. In this study, deflection analysis at the MLA/Si diaphragm was investigated by Finite Element Method. Analysis of Si diaphragm combined with MCA has been implemented into the ANSYS (Solid5 and Solid45). On the basis of this structure, deflection versus MCA number of layers has been modelled and MCA/Si contact area characteristics with different diaphragm conditions were analyzed. Consequently, it is expected that fabrication technology of MCA/Si diaphragm could be usefully applied for the fabrication process of high-performance piezoelectric MEMS devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.327-327
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• 2007

This paper reports the simulation results of piezoelectric microspeakers due to structural changes(diaphragm materials, corrugation width and electrode shapes). When we compared the dependence of diaphragm material properties, the microspeaker with LTO(Low Temperature Oxide) diaphragm shows higher deflection than that of silicon nitride diaphragm, even though the resonant frequencies are almost same in both cases. In case of circular-electrode microspeaker, the deflection of diaphragm is about $16\;{\mu}m$ at 20 V, and it decreases as the corrugation width is decreased. However, the deflection of diaphragm with the square-electrode reveals almost twice times higher value at the same applied voltage than the circular one, and it increases as the corrugation depths are decreased from $30\;{\mu}m\;to\;10\;{\mu}m$. The first resonant frequency of microspeakers present about 1.8 kHz in circular-electrode and 1.2 kHz in square-electrode, respectively.

• Elastomers and Composites
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• 제55권3호
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• pp.222-228
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• 2020

Rubber materials, used in nuclear power plants, need high heat-oxidation resistance to curing or cracking under a heat aging environment. This is because they are applied to environments with high temperature, high humidity, and radiation exposure. Nuclear radiation causes additional hardening or degradation, therefore, rubber materials need radiation resistance that satisfies the general and any accidental conditions produced in the power plant. Therefore, in this study, we developed a rubber material with excellent heat and radiation resistance for the diaphragm seal of a nuclear steam generator nozzle dam. The rubber material greatly improved the reliability of the steam generator nozzle dam. In addition, 30 inch and 42 inch diaphragm seals were manufactured using the developed rubber material. A nozzle dam was installed in a nuclear power plant and tested under the same conditions as a steam generator to evaluate safety and reliability. In the future, the performance and safety of diaphragm seals developed through field tests of nuclear power plants will be evaluated and applied to currently operating and new nuclear power plants.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2961-2966
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• 2007

When the pressure at the weak spot established at a certain part of a high pressure vessel or piping system exceeds a design pressure, this weak spot is burst, and the pressurized gas emitted through the weak spot will cause a compression wave system. In this connection, in the present study, an experimental study by using a conventional shock tube facility is performed to estimate the effects of the material of diaphragm, curvature radius and thickness of materials on the valve opening time in diaphragm. Pressure sensor having 500kHz in natural frequency is installed at 35mm downstream of the rupture diaphragm to measure the static pressure history of propagating and being accumulated compression wave. 4 kinds of materials are used as diaphragm that is aluminium, copper, stainless steel and zinc. The diaphragm radii of curvature R are ${\infty}$, 120mm and 60, respectively. And the depth for $90^{\circ}$ groove is 0.04mm. It is found that the smaller the tensile strength and elongation of the rupture diaphragm is, the smaller the radius of curvature of the rupture diaphragm is, and for the same conditions the thinner the thickness of the rupture diaphragm is, the shorter the valve opening time becomes. Also, the tensile strength, elongation and the radius of curvature of the rupture diaphragm for the same conditions are smaller, the maximum pressure rise caused by the coalescences of the compression wave is smaller. Finally the pressure ratio is higher, the valve opening time is shortened and gradient of pressure increment is more steepen.

• 한국전기전자재료학회논문지
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• 제14권12호
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• pp.987-993
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• 2001

In this paper, we presents the construction details and output characteristics of a thick film piezoresistive strain gage. The thick film was printed on the ceramic diaphragm back side by screen printing and cured at 850$^{\circ}C$. The strain distribution and deflection on ceramic diaphragm were performed with finite-element method(FEM tool ANSYS-5.3). Various thick film strain gage characteristics were analysed, including nonlinearity, hysteresis, stability and sensitivity of thick film strain gages.

• 한국음향학회지
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• 제25권5호
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• pp.222-228
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• 2006

본 연구에서는 마이크로스피커에 사용되는 진동판의 재질에 따른 음향특성을 연구하였다. 진동판의 재료가 달라지면 영률과 밀도가 바뀌게 되고, 그로 인하여 재질에 따라서 음속과 스티프니스 값이 변하게 된다. 그 결과로써, 공명진동 수는 PEl, PPS, PET, PEN의 순서로 점차 높게 나타났으며, 이는 이론적으로 예측된 결과와 정확히 일치하였다. 진동판의 재질은 저음으로부터 최저공명진동수 ($f_s$)까지 음압이 증가하는 변화율이나 최고한계공명진동수 ($f_h$)에는 영향을 주지 않았다. 그러나 임피던스 특성에서 얻어진 공명진동수가 낮은 재질의 순서대로 저음영역이 강하게 나타났다.

• 한국전기전자재료학회논문지
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• 제21권6호
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• pp.556-561
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• 2008

This paper reports the characteristics of piezoelectric microspeakers that are audible in open air with high quality piezoelectric AlN thin film according to the materials properties. When we use a tensile-stressed silicon nitride diaphragm as a supporting layer, the Sound Pressure Level (SPL) is relatively small and constant at low frequency region and shows about 70 dB at 10 kHz. However, in case of a compressively stressed composite diaphragm, the SPL of the fabricated microspeakers shows higher output pressure than those of a tensile-stressed diaphragm. It produces more than 66 dB from 100 Hz to 15 kHz and the highest SPL is about 100 dB at 9.3 kHz with $20V_{peak-to-peak}$, sinusoidal input biases and at 10 mm distances from the fabricated microspeakers to the reference microphone. From the experimental results, it is superior to have a compressively composite diaphragm in order to produce a high SPL in piezoelectric microspeaker.

• Elastomers and Composites
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• 제35권1호
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• pp.4-11
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• 2000

어큐뮬레이터에 사용되는 얇은 막 형태의 고무다이아프램은 외부의 맥동 및 충격압력을 흡수하고 유체의 수송과 압력을 전달하는 역할을 수행하며, 압력 변화에 따른 변형 거동은 어큐뮬레이터의 특성을 결정하는 중요한 설계 변수이다. 고무다이아프램은 고무 자체의 비선형성에 의한 비선형거동과 작은 압력 변화에도 큰 변형을 일으키는 대변형 거동을 나타내며, 임의 압력 이상에서는 고무다이아프램이 변형된 후 용기에 접촉되는 현상이 나타난다. 본 연구에서는 비선형 대변형 해석과 접촉 해석 둥이 용이한 구조해석 소프트웨어인 MARC를 이용하여 두 가지 형상에 대한 고무다이아프램의 거동을 해석하여, 고무 물성 변화와 압력 변화에 따른 변형 거동을 예측하고 파손 취약 부위로 예상되는 다이아프램의 고정 부위에서의 응력을 완화하기 위한 설계 개선 방안을 제시하였다.

• 한국가스학회지
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• 제21권3호
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• pp.33-38
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• 2017

국내 CNG Bi-fuel Kit를 개조한 차량들은 대부분 Diaphragm 감압방식을 적용한 기계식 레귤레이터를 장착하여 운행 중에 있다. 하지만 Diaphragm의 재질 특성 및 기계식 압력제어 방식의 특성 상 다양한 문제점들이 발생되고 있으며, 이를 개선하기 위한 연구들이 진행되고 있다. 본 연구에서는 CNG 차량용 레귤레이터의 압력제어방식에 따른 성능특성 확인 및 비교 분석 진행을 통해 개선방안을 도출하고자 하였다. 실험 결과에 따르면 Diaphragm을 적용한 감압방식이 Piston을 적용한 방식보다 일반적인 성능에서 유리하였으나 주변 온도환경 변화에 따른 변동 폭이 큰 것을 확인하였다. 또한 전자식 압력제어를 통해 레귤레이터의 일반적인 성능을 향상시킬 수 있음을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.677-680
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• 1999

Rapid developing automation technology enhances the need of sensors. Among many materials, silicon has the advantages of electrical and mechanical property, Single-crystalline silicon has different piezoresistivity on 야fferent directions and a current leakage at elevated temperature, but poly-crystalline silicon has the possibility of controling resistivity using dopping ions, and operation at high temperature, which is grown on insulating layers. Each wafer has slightly different thicknesses that make difficult to obtain the precisely same thickness of a diaphragm. This paper deals with the fabrication process to make poly-crystalline silicon based pressure sensors which includes diaphragm thickness and wet-etching techniques for each layer. Diaphragms of the same thickness can be fabricated consisting of deposited layers by silicon bulk etching. HF etches silicon nitride, HNO$_3$+HF does poly -crystalline silicon at room temperature very fast. Whereas ethylenediamice based etchant is used to etch silicon at 11$0^{\circ}C$ slowly.