• 한국자동차공학회논문집
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• 제14권4호
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• pp.164-173
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• 2006

In the electro-hydraulic injector for the common rail Diesel fuel injection system, the injection nozzle is being opened and closed by movement of a injector's needle which is balanced by pressure at the nozzle seat and at the needle control chamber, at the opposite end of the needle. In this study, the piezo actuator was considered as a prime movers in high pressure Diesel injector. Namely a piezo-driven Diesel injector, as a new method driven by piezoelectric energy, has been applied with a purpose to develop the analysis model of the piezo actuator to predict the dynamics characteristics of the hydraulic component(injector) by using the AMESim code. Aimed at simulating the hydraulic behavior of the piezo-driven injector, the circuit model has been developed and verified by comparison with the experimental results. As this research results, we found that the input voltage exerted on piezo stack is the dominant factor which affects on the initial needle behavior of piezo-driven injector than the hydraulic force generated by the constant injection pressure. Also we know the piezo-driven injector has more degrees of freedom in controlling the injection rate with the high pressure than a solenoid-driven injector.

• Journal of Advanced Marine Engineering and Technology
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• 제35권8호
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• pp.1063-1069
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• 2011

본 논문은 2 MW급 풍력터빈 3기로 구성된 6 MW 해상풍력발전단지의 풍력터빈 이격거리에 따른 공기역학적 출력 변화를 전산유동해석을 활용하여 연구한 것이다. 육상 뿐만 아니라 해상풍력발전단지에 있어서 레이아웃 설계는 풍력발전단지 초기 투자비, 년간 발전량 및 유지보수비에 영향을 끼치는 핵심 인자이다. 각 풍력터빈 로터에 대해서 모멘텀 소스를 가지는 액츄에이터 디스크가 아닌 완전한 3-D 모델에 대해서 전산유동해석 기법을 적용하여 연구하였으며 이는 기술적으로 큰 의미를 가진다. 본 논문의 연구결과는 향후 해상풍력발전단지 레이아웃 설계에 유용하게 적용될 수 있을 것이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.899-903
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• 2004

A limit switch box is used for a indicator of a valve actuator. This device indicates an opening and closing of a valve or throttle in a valve actuator. In ship, equipments are required safe and robust because of a rough environment and a specific condition during a voyage. However, the limit switch box is used in an indoor environment generally. Thus, a new limit switch box must be developed which can be used at an outdoor environment. This study designed the limit switch box. The housing of the limit switch box was made by an aluminium die cast method with surface painting after anodizing or chromate coating. In order to evaluate the endurance of the housing, the endurance tests against salt water have been conducted. Experiment results showed that the proposed device provides a reliable performance against salt water.

• 한국공작기계학회논문집
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• 제15권1호
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• pp.8-16
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• 2006

The communication through optical fiber is taking an important role of the expansion of communication network with excellent transmitting rate and quality. As the optical communication is introduced to the backbone network at first and becomes a general communication method of network, the demand of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, and WDM(Wavelength Division Multiplexing) element increases. The alignment and the attachment technology are very important in the fabrication of optical elements. In this paper, the driving mechanism of ultra precision stage is studied with the aim of optimal design of stage. The travel and the resolution of stage are investigated. The hysteresis of the stage is generated because of PZT actuator. The hysteresis and the inverse hysteresis are modeled in X, Y, and Z-axis motion. The input data of desired displacement of the stage according to input voltage is obtained from the inverse hysteresis equation. In the result of experiments with the input data, the errors due to hysteresis are well compensated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.723-726
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• 2002

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research of dynamic characteristics is very deficient. In this paper, the helical spring is fabricated with NiTi SMA wire of high resistivity The farce, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA actuator is analyzed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.836-839
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• 2005

A limit switch box is used for a indicator of a valve actuator. This device indicates an opening and closing of a valve or throttle in a valve actuator. In a ship, equipments are required safety and robustness because of a rough environment and a specific condition during a voyage. However, the limit switch box is used in an indoor environment generally. In order to evaluate the endurance of the limit switch box used in an indoor environment, the endurance tests against salt water have been conducted. Experiment results showed that the limit switch box was corroded severely. Thus, this study developed a new limit switch box which can be used at an outdoor environment. The housing of the developed limit switch box was made by an stainless steel to prevent corrosion.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1613-1616
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• 2007

A microgripper using thermal actuator and SU-8 polymer was designed and fabricated to manipulate cells and microparts. A chip size of a microgripper was 3 mm ${\times}$ 5 mm. The thermally actuated microgripper consisted of two couples of hot and cold arm actuators. The high thermal expansion coefficient, 52 $ppm/^{\circ}C$, of SU-8 compared to silicon and metals, allows the actuation of the microgripper. Thickness and width of SU-8 as an end-effector were 26 ${\mu}m$ and 80 ${\mu}m$, respectively. Initial gap between left jaw and right jaw was 120 ${\mu}m$. The ANSYS program as FEM tool was introduced to analyze the thermal distribution and displacement induced by thermal actuators. $XeF_2$ gas was used for isotropic silicon dry etching process to release SU-8 end-effector. Mechanical displacements of the fabricated microgripper were measured by optical microscopy in the range of input voltage from 0 V to 2.5 V. The maximum displacement between two jaws of a microgripper Type OG 1_1 was 22.4 ${\mu}m$ at 2.5 V.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.425-428
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• 2006

Recently, Direct Methanol Fuel Cell (DMFC) for portable devices has been received much attention because DMFC has a possibility of higher energy density than electrical batteries and smaller size than other fuel cells. This paper presents the fabrication and test of a thermopneumatic microactuator with a phase change for DMFC. A microactuator consists of an inlet an outlet a chamber, a heater and a sensor of resistance temperature detector(RTD). The micoractuator is fabricated by the spin-coating process, the lithograph process, the deep RIE process and so on. The total size of microactuator is $20{\times}20{\times}0.53mm^3$. When the current is applied, the heater heats liquid in chamber. As a result the liquid vaporizes. The response of temperature in the chamber was measured using thermocouple The changed temperature is $3^{\circ}C$ for 5 sec at 0.032W.

• 전기학회논문지
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• 제62권8호
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• pp.1095-1100
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• 2013

Piezo devices have large power density and simple structure compared with conventional electrical motors. Thus they can generate larger forces than the conventional actuators with small size. Their resopnses to commands are also very fast and thus the bandwidths are very wide. Thus the piezo devices are expected to be used widely in the future for actuating devices requiring fast response and large actuating force with small size. However, the piezo actuators need high voltage with high driving current due to their large capacitive property. In this paper, proposed is a simple method to drive piezo devices using voltage inversion circuit with coli inductance. The coil inductance carries the charges in the piezo device to the opposite side, inverting the polarity of the applied voltage, thus saving the power to drive the device with AC voltages. Experiments with real circuit demonstrates that the proposed scheme can improve the energy efficiency very much.

• 한국유체기계학회 논문집
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• 제6권3호
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• pp.51-57
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• 2003

Characteristics of the high frequency pulsatile flow have been investigated experimentally to understand the flow phenomena in the hydraulic system. One axis fatigue test bed, which is widely used for automobile field test, is used. Four pressure transducers, an amplifier and a A/D convertor are used to obtain the high frequency pulsatile pressure waveform in hydraulic system. The characteristics of frequency are analyzed by power spectrum method. According to the variations of pump input pressure and actuator acceleration frequency, the pressure is measured with or without an accumulator. The amplitude of pressure with accumulator is very lower than those without accumulator due to absorbing function of accumulator. As the frequency of actuator acceleration is increased, the effect of accumulator become very important to decrease the amplitude of pulsatile pressure waveform with high frequencies.