• 한국해양공학회지
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• 제27권2호
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• pp.107-113
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• 2013

Most natural river reach are approximately balanced with respect to sediment inflow and outflow. Dam construction dramatically alters this balance, creating an impounded river reach characterized by extremely low flow velocities and efficient sediment trapping. The impounded reach will accumulate sediment and lose storage capacity until a balance is again achieved, which would normally occur after the impoundment has become "filled up" with sediment and can no longer provide water storage and other benefits. This paper aims to investigate the sediment removal process in dam reservoir using simultaneously pressure flushing operation and vibrator machine. The main objective of this study is to identify the effect of vibrator in flushing cone dimensions. To achieve the objectives of present study, laboratory test have conducted under different hydraulic conditions such as two bottom outlets with diameter equal to 2" and 3", five discharges 0.23, 0.53, 1.21, 1.53 and 2.1 lit/s and only one water depth above the center of bottom outlets. Using the vibrator machine mounted into the reservoir and close to the bottom outlet, different frequency e.g. 20, 35 and 50 HZ, have been introduced to the deposited sediment at the vicinity of outlet. The results indicate that the volume and width of flushing cone are strongly affected by frequency of vibrations. The results indicate that the volume and width of flushing cone are strongly affected by frequency of vibrations.

• 한국음향학회지
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• 제27권6호
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• pp.271-278
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• 2008

압전판의 길이나 폭에 따라 두께가 변화하는 압전 세라믹을 사용하여 광대역 특성을 구현하는 초음파 트랜스듀서에 대하여 압전진동자의 측면에서 본 형태에 따른 전기-음향적 특성해석을 이론적으로 수행하였다. 압전진동자의 길이방향에 따른 두께 변화를 지수함수의 조합으로 표현하고 이 함수를 이용하여 압전진동자의 전기단자에서 본 자유 어드미턴스 및 파워전달함수에 대한 식을 도출하였다. 대표적인 PZT압전 세라믹을 예로 들어 압전 진동자의 측면 형태변화에 따른 비 대역폭을 고찰해본 결과 넓은 대역폭를 얻기 위한 최적의 형태가 존재함을 알 수 있었으며, 압전진동자의 최대두께에 대한 최소두께 비가 자아짐에 따라 대역폭은 100%이상까지도 넓어질 수 있으나 파워전달함수는 반대로 감소하는 경향을 확인할 수 있었다. 또 압전진동자의 길이가 길어질수록 전달함수의 크기는 증가하나 광대역 특성을 갖는 압전진동자의 형태는 매우 한정적이 됨을 확인할 수 있었으며 이는 고효율의 광대역 초음파 트렌스듀서 제작에 있어서는 정밀한 가공이 요구됨을 확인할 수 있었다.

• 감성과학
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• 제13권4호
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• pp.703-710
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• 2010

본 연구에서는 선행 연구에서 개발된 촉각 자극 시스템의 시스템적인 문제, 자극 제어에 관한 문제, 기타 부가적인 문제들을 보완할 수 있는 촉각 자극기를 개발하였다. 개발된 장치는 제어부(control unit), 구동부(drive unit), 진동부(vibrator)의 세부분으로 구성된다. 제어부는 E-Prime 소프트웨어로부터 명령을 전송받고 진동 자극 신호를 발생한다. 구동부는 촉각 자극기가 효과적으로 진동 자극을 발생할 수 있도록 충분한 전류를 공급한다. 진동부는 작은 동전(coin) 형 진동기(vibrator)와 벨크로(velcro)로 구성되며 피험자의 손에 쉽게 고정 할 수 있도록 제작하였다. 개발된 장치는 소형, 경량, 저전력 구동, 간단한 구조, 최대 35개의 자극 채널, 시각 및 청각과의 다양한 자극 조합을 지연시간 없이 제시할 수 있도록 설계 되어 시스템적인 문제들을 보완하였다. 자극의 크기와 시간을 10단계로 조절할 수 있도록 하고, 넓은 동작주파수 범위를 확보하여 자극 제어에 관한 문제들을 보완하였다. 저전압 구동으로 인체에 대한 안정성을 확보하고, 손가락 이외에 신체의 어느 부분이든 자극 제시가 가능하도록 제작하였다. 특히 본 시스템은 인지과학 연구에서 범용으로 사용되는 소프트웨어인 E-Prime을 기반으로 개발되었기 때문에 활용성이 매우 높을 것으로 판단된다.

• 해양환경안전학회지
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• 제7권2호
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• pp.1-11
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• 2001

Many investments and works being continued to preserve green ocean in each countries of the world. Especial1y, the researches on the prevention of marine oil pollution being strengthened. It is not easy to disclose sludge oils that were produced necessarily in the ships operation, so that they are transferred to shore treating facility after collected inside the ship＇s sludge tank mostly. However, this shore transferring method is not only costly and time consuming but also entails risk of oil pollution. In this regard, it will be the best way to manage the sludge oils inside ship itself. The purpose of this study is to device an ultrasonic breaking systems which recycle the sludge oil from ships into usable oil to be burnt. In this paper, the first place, matrix structures of sludge fuel oil(SFO) and sludge lubricating oil(SLO) with the irradiation time for ultrasonic vibrator were interpreted. And, erosion damage for vibrator horn tip which is one of important part of ultrasonic breaking systems was examined under such an environment of the sludge oils. The material for horn tip is being made of SS41 steel and its erosion phase was investigated with variation of the vibration amplitude of 50${\mu}{\textrm}{m}$ and 24${\mu}{\textrm}{m}$ as well as the change of temperature in the oil environments. It is suggested that the experimental results can be helpful to the development of sludge oil disposing systems for the vessel.

• Journal of Power Electronics
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• 제3권2호
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• pp.139-144
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• 2003

In this paper, 11 and 13 layered step-down piezoelectric transformers were fabricated and their electrical characteristics have been analyzed for AC-adapter. When the voltage is applied to the driving piezoelectric vibrator polarized in the longitudinal direction, the output voltage is generated at the generating piezoelectric vibrator polarized in the thickness direction due to the piezoelectric effects. From the piezoelectric direct and converse effects, symbolic expressions between the electric inputs and outputs of the step-down piezoelectric transformer are derived with an equivalent circuit model. With those expressions, load and frequency characteristics are discussed through the simulations. Output voltage and current from a 11-layered and a 13-layered piezoelectric transformers were measured under the different load and frequency conditions. First we measured resonant frequency from impedance curve and got equivalent impedance value of the piezoelectric transformer from admittance plot. It was shown from experiments that output voltage increase s and resonant frequency changes according to the various resistor loads. Output current decreases inversely proportional to the change of loads. Moreover, the measured output voltage and current are well matched with the simulated results obtained from the proposed equivalent circuit model. Furthermore, a new step-down piezoelectric transformer has been suggested to Increase the output power based on a simulation result having a driving piezoelectric vibrator polarized thickness direction.

• Transactions on Electrical and Electronic Materials
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• 제5권3호
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• pp.109-112
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• 2004

In this study, in order to develop the low temperature sintering ceramics for ultrasonic vibrator, Pb(Sb$\_$$\frac{1}{2}$/Nb$\_$$\frac{1}{2}$/) O$_3$-Pb(Ni$\_$1/3/Nb$\_$2/3/)O$_3$-Pb(Zr$\_$0.48/Ti$\_$0.52/)O$_3$ ceramics were manufactured as a function of the amount of CuO addition, and their dielectric and piezoelectric characteristics were investigated. With increasing CuO addition, the grain size and density increased up to 0.3 wt% CuO addition. Taking into consideration electromechanical coupling factor(k$\_$p/) of 0.53, mechanical quality factor(Q$\_$m/) of 423, dielectric constant($\varepsilon$$\_$r/) of 1,759 and piezoelectric constant(d$\_$33/) of 362pC/N, it could be concluded that 0.5 wt% CuO added composition ceramic sintered at 920$^{\circ}C$ was suitable for ultrasonic vibrator application.

• 한국전기전자재료학회논문지
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• 제18권3호
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• pp.243-247
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• 2005

In this study, in order to develop low temperature sintering ceramics for ultrasonic vibrator application, PNW-PMN-PZT system ceramics were manufactured according to the amount of CaCO$_3$ addition, and their piezoelectric, dielectric and microstructural characteristics were investigated. The ceramic specimens could be sintered at sintering temperature below 1000 $^{\circ}C$ due to the effect of Li$_2$CO$_3$-CaCO$_3$ liquid phase produced by the reaction of Li$_2$CO$_3$ and CaCO$_3$. At 0.2 wt% Li$_2$CO$_3$ and 0.25 wt％ CaCO$_3$ added specimen sintered at 920 $^{\circ}C$, the density, electromechanical coupling factor(k$_{p}$), mechanical quality factor(Q$_{m}$) and dielectric constant showed the optimal value of 7.78 g/㎤, 0.49, 1396, and 1300, respectively, for ultrasonic vibrator application.ion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.53-56
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• 2000

Piezoelectric ceramics can provide electro-mechanical transduction with high stresses but low displacement. To obtain larger displacements, several mechanical amplifying structures have been used. High alternating displacements can be obtained using resonant structure. In this paper, we designed a bolt-tightened Langevin type ultrasonic vibrator whose resonant frequency is 50[kHz] and ceramics are multilayered. FEM(Finite Element Methode) was employed to calculate. the resonant frequencies and maximum displacements of designed vibrators. The designed resonant frequency and computer calculated frequencies were coincided. When input voltages were increased, the maximum displacements also rose. As AC voltage was applied, the maximum displacement were shown sinusoidal changes. Terminal input admittance over a frequency range spanning the resonant frequency were calculated. ANSYS was used to find resonant frequencies and calculate displacements of vibrators.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.33-34
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• 2005

In this study, in odor to develop low temperature sintering multilayer piezoelectric actuator and ultrasonic vibrator, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3$ and $Na_2CO_3$ as sintering aids and their piezoelectric and dielectric characteristics were investigated according to the addition of dopant CuO and $Fe_2O_3$, respectively. The CuO added PMN-PNN-PZT ceramics improved mechanical quality factor Qm due to the acceptor doping effect. And also, $Fe_2O_3$ reacted as softner in this composition system in addition to the increase of grain size and sinterability. Taking into consideration electromechanical coupling factor kp of 0.62, dielectric constant $\varepsilon_r$, of 1275, Piezoelectric $d_{33}$ constant of 377[pC/N] and mechanical quality factor Qm of 975, it was concluded that the ceramics with the $Fe_2O_3$, added composition sintered at 900[$^{\circ}C$] were best for the multilayer piezoelectric actuator and ultrasonic vibrator application.

• 동의생리병리학회지
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• 제20권5호
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• pp.1223-1225
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• 2006

The purpose of this study was to examine the effects of enlarging the breast by the B-secret I , II( vaccum vibrator) in women. This study was one group in a pre-test / post-test desgian with repeated measures. The experimental group of 30 patients were selected through sampling from L-oriental medicine in the P-city. The subjects received B-secret 1 , 11 ( vaccum vibrator) for 15 - 20minutes / 1 day during three months . All of the subjects were examined on the volume-size of the breast & the degree on the improvement. Prior and post surveys were measured before and after the experiment. The volume and size of the breast were measured the girth of the chest on the breast and below breast, the range on nipple and the middle point of the clavicle, the range on nipple and the middle point of the sternum, the range out of two nipple, the lineal and obligue line distance on nipple and the under crumples of breast, the height on the nipple and the under crumples of the breast, the diameter of the girth of nipple. As the effect on enlargement and the degree on the improvement of breast by B-secret 1 , 11 ( vaccum vibrator) were observed the girth of the chest on the breast, the range on nipple and the middle point of the clavicle, the range on nipple and the sternum, the height on the nipple and the under crumples of the breast.