• 한국기계가공학회지
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• 제12권1호
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• pp.97-103
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• 2013

A new precision positioning mechanism for stage was been developed by Displacement Magnification Device(DMD) in this paper. The DMD was composed of the beam and multilayer piezoelectric actuators. The theoretical and experimental analysis of DMD to enlarge displacement more then 50times were discussed. And the 2-axis stage by using displacement amplification apparatus was added in the new DMD, and it was able to do it through finite element analysis and experiment. As the results, the magnification of DMD can be obtained about $100{mu}m$ displacement to the 10V input voltage($1.5{mu}m$). And the about 50nm of linearity error in the $30{mu}m$ measurement range and 20times of the amplification in displacement can be measured. In addition, the experimental results are confirmed the possibility of millimeter displacement characteristics and correspond to finite element analysis results.

• 한국정밀공학회지
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• 제29권6호
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• pp.671-679
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• 2012

This paper presents an estimation procedure for axial displacement in spindle equipped with angular contact ball bearings due to rotational speed. High-speed spindle-bearing system experiences axial displacement due to thermal expansion and rotational speed-dependent characteristics of angular contact ball bearings. This paper deals with the axial displacement caused by the rotational speed-dependent effects such as centrifugal force and gyroscopic moments. To this end, a bearing dynamic model is established that includes all the static and dynamic properties of angular contact ball bearing. An analytical formula to calculate the axial displacement based on contact angles between ball and races is derived to discuss the physics regarding the axial displacement in spindle. The proposed dynamic model is compared with a reference and a commercial program. Numerical examples are presented to show the effects of centrifugal force and gyroscopic moment on the axial displacement. The proposed model is also validated with an experimental result.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 가을 학술발표회 논문집
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• pp.242-249
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• 1995

In order to search more efficient structural control algorithm, several closed-loop algorithm are developed. Among those, feedback control algorithm using parameters as displacement velocity, and acceleration has been studied. In this paper, especially the characteristics of accleration feedback is studied as more efficient control algorithm than any others. Furthermore the fact that ATMD with acceleration feedback system further reduce the variance of structural displacement rather than with displacement or velocity feedback system will be examined and proved.

• 대한기계학회논문집
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• 제18권1호
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• pp.232-239
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• 1994

This paper presents an effective way of improving fuel consumption for a variable displacement engine. The improvement of fuel consumption can be accomplished by means of deactivating inlet and exhaust valves, reducing the number of effective cylinders of a four-cylinder gasoline engine that is mounted on a domestic compact automobile.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.509-512
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• 1995

A new modeling incorporating the role of control arm is proposed for the Macpherson type suspension system. Vertical displacement of the sprung mass and angular displacement of the control arm are selected as main control variables in the new modeling. With the same values of suspension vehicle parameters the conventional modeling and the new modeling are compared in terms of open loop characteristics.

• 터널과지하공간
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• 제2권2호
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• pp.237-250
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• 1992

The cavities formed by the excavation of coal seam cause unstable within rock body, leading to large displacement around adjacent roadway. This displacement brings the closure of roadway and deformation of support. Therefore, it is necessary to understand and predict the deformation characteristics of roadway while coal seam is under excavation. In this study, the observed displacements are compared with the calculated ones through the analysis using Linear Boundary Element Mothod under the elastostatic conditions, in order to determine the virgin stress state and deformation modulus which affect the deformation characteristices.

• 한국태양에너지학회 논문집
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• 제25권4호
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• pp.133-139
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• 2005

In this paper, the ventilation performance of suspended particulates in indoor side was investigated by step-down method. Experiments were performed in function of mechanical ventilation types and locations of supply and extract air. The type 2 ventilation system shows the highest removal characteristics rather than other 2 types. It means that the displacement ventilation has also good decay rates of concentration compared to mixing ventilation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1157-1161
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• 2003

A novel actuator with built-in the displacement and the thrust control function is presented in this paper. This actuator is a kind of compact hydraulic cylinder system which consists of a hydraulic cylinder, a spool, a sleeve, a mechanical feedback mechanism and a stepping motor. The displacement and thrust is in proportion to the rotational angle of stepping motor by the mechanical feedback. In order to investigate characteristics of this actuator, simulation study and preliminary experiments are conducted. Through the preliminary experiment this actuator is very effective in the control for displacement and thrust. Also, it became obvious that the stability of system can be adjusted by using the restrictor with the effect of velocity feedback. Furthermore, this paper explained that a flexible compliance control could be realized by adjusting the feedback weighting in the actuator.

• Journal of Advanced Marine Engineering and Technology
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• 제30권2호
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• pp.284-290
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• 2006

For the case of high head and critical low flow rate range of micro hydropower resources, it requires very low specific speed turbines which are lower than conventional impulse turbine's specific speed. In order to satisfy the request for very low specific speed turbine with high efficiency, a new positive displacement turbine is developed. The performance characteristics of the new turbine is tested and compared with a conventional impulse turbine, which is used for automatic water faucet system. The purpose of present study is to develop an high performance turbine that can be used to extract micro hydropower potential of a water supply system. The test results show that the positive displacement turbine is much more efficient than the conventional turbine and it can sustain high efficiency under the wide range of operating conditions. The pressure pulsations at the inlet and outlet of the positive displacement turbine can be considerably minimized by using simple pressure damper.

• 한국자기학회지
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• 제25권1호
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• pp.27-30
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• 2015

본 연구에서는 새로운 타입의 변위센서를 개발하기 위한 목적으로, 페라이트코어를 이용한 인던턴스와 외부 캐패시턴스를 이용하는 LC공진자를 제작하고 특성을 검토하였다. 개별 공진자의 임피던스의 주파수의존성을 분석하였고, 두 개의 공진자가 인접해 있을 때 자체 인덕턴스와 상호 인덕턴스에 부합하는 주파수에서 각각의 공진이 일어나는 것을 알 수 있었다. 공진주파수는 5~17 mm의 변위에 대해서 선형적으로 변화하였으며, 제안된 방법으로 정밀한 변위를 측정할 수 있음을 알 수 있었다.