• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.235-239
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• 2008

Cable systems are a construction of elements carrying only tension and no compression or bending in membrane structure. Tensile membrane structures are most often used as roofs as they can economically and attractively span large distances. But cable systems have weaknesses to vibration by earthquake, wind and vehicle loads. Damage detection of cable systems by using existing safety diagnosis is difficult to detect the characteristic change of overall structural action. If cable snaps are occurred to cable release and tear in tension structures, these are set up a vibration. So, we used piezo-electric materials, and The principle of operation of a piezoelectric sensor is that a physical dimension, transformed into a force, acts on two opposing faces of the sensing element. In this study, the development on test method of cable system is proposed and tested by tensile strength using piezo-electric materials.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.68-71
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• 2000

A tool holder system has been designed to measure cutting forces in diamond turning. This system includes a 3-component piezo-electric tranducer. In this research, tool holder system is modeled by considering the element dividing, material properties, and boundary conditions using MSC/PATRAN. Mode and frequency analysis of structure is simulated by MSC/NASTRAN, for the purpose of developing the effective design. In addition, tool holder system is verified by vibration test using accelerometer. This system will aid to the development of Fast Tool Servo.

• 한국분무공학회지
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• 제15권1호
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• pp.25-30
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• 2010

The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail direct injection system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors with different electric driving characteristics, including solenoid-driven and piezo-driven type. Namely three common-rail injectors with different electric current wave were investigated in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. As this research results, it was found that pilot injection of common-rail system was effected by rate of injection with different electrical characteristic for driving the injector.

• Computers and Concrete
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• 제26권1호
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• pp.75-94
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• 2020

The aim of this research is to investigate free vibration of a novel five layer Timoshenko microbeam which consists of a transversely flexible porous core made of Al-foam, two graphen platelets (GPL) nanocomposite reinforced layers to enhance the mechanical behavior of the structure as well as two piezo-magneto-electric face sheets layers. This microbeam is subjected to a thermal load and resting on Pasternak's foundation. To accomplish the analysis, constitutive equations of each layer are derived by means of nonlocal strain gradient theory (NSGT) to capture size dependent effects. Then, the Hamilton's principle is employed to obtain the equations of motion for five layer Timoshenko microbeam. They are subsequently solved analytically by applying Navier's method so that discretized governing equations are determined in form of dynamic matrix giving the possibility to gain the natural frequencies of the Timoshenko microbeam. Eventually, after a validation study, the numerical results are presented to study and discuss the influences of various parameters such as nonlocal parameter, strain gradient parameter, aspect ratio, porosity, various volume fraction and distributions of graphene platelets, temperature change and elastic foundation coefficients on natural frequencies of the sandwich microbeam.

• Coupled systems mechanics
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• 제2권1호
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• pp.53-83
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• 2013

Sea waves induce significant pressures on coastal surfaces, especially on rocky vertical cliffs or breakwater structures (Peregrine 2003). In the present work, this hydrodynamic pressure is considered as the excitation acting on a piezoelectric material sheet, installed on a vertical cliff, and connected to an external electric circuit (on land). The whole hydro/piezo/electric system is modeled in the context of linear wave theory. The piezoelectric elements are assumed to be small plates, possibly of stack configuration, under a specific wiring. They are connected with an external circuit, modeled by a complex impedance, as usually happens in preliminary studies (Liang and Liao 2011). The piezoelectric elements are subjected to thickness-mode vibrations under the influence of incident harmonic water waves. Full, kinematic and dynamic, coupling is implemented along the water-solid interface, using propagation and evanescent modes (Athanassoulis and Belibassakis 1999). For most energetically interesting conditions the long-wave theory is valid, making the effect of evanescent modes negligible, and permitting us to calculate a closed-form solution for the efficiency of the energy harvesting system. It is found that the efficiency is dependent on two dimensionless hydro/piezo/electric parameters, and may become significant (as high as 30 - 50%) for appropriate combinations of parameter values, which, however, corresponds to exotically flexible piezoelectric materials. The existence or the possibility of constructing such kind of materials formulates a question to material scientists.

• 대한기계학회논문집B
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• 제36권10호
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• pp.971-977
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• 2012

고압 인젝터의 성능은 디젤 연소엔진의 동력, 배출물, 연료소모와 직접적인 관계가 있다. 본 논문에서는 솔레노이드 코일과 피에조 세라믹으로 구동되는 커먼레일 디젤 분사용 인젝터의 응답 특성을 AMESim 코드를 사용하여 상대 비교 연구를 수행하였다. 따라서 연료압력, 분공경을 주요 해석변수로 설정하였다. 본 연구를 수행한 결과, 솔레노이드 구동 인젝터에 비해 피에조 구동 인젝터가 상대적으로 더 빠른 응답성과 더 높은 제어성을 가짐을 알 수 있었으며, 특히 다단분사 적용시, 이런 결과가 매우 효과적임을 확인할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.475-476
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• 2007

• 한국ITS학회:학술대회논문집
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• 한국ITS학회 2003년도 제2회 정기총회 및 추계학술대회
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• pp.56-61
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• 2003

• 한국정밀공학회지
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• 제24권10호
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• pp.19-24
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• 2007

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.393-394
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• 2008