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Development of SFM System for Nano In-Process Profile Measurement
권현규,최성대,홍성욱,Kweon, Hyun-Kyu,Choi, Seong-Dae,Hong, Sung-Wook The Korean Society of Manufacturing Process Engine 2004 한국기계가공학회지 Vol.3 No.2
In this paper, we propose a new multi-purpose Scanning Force Microscope (SFM) system. The system can be used for nano/micro-scratching, in-process profile measurement, and observation of potential surface defects which occur during the scratching in air or liquid. Experimental results of nano/micro-scratching show that the smallest scratching depth can be controlled to be 10nm, which corresponds to the stability of the SFM system. Profile measurements of nano/micro-scratching surfaces have also been performed by the method of on-machine measurement and in-process measurement. Two measurement results were in good agreement with each other. The maximum difference was approximately 10 nm, which was mainly caused by the sampling repeatability error that influences the measurement accuracy Also, micro-defects on the micro-scratching surface were successfully detected by the SFM system. It was confirmed that the number of micro-defects increases when the surface is subjected to a cyclic bending load. The maximum depth was less than 100nm.
권현규,최성대,Kweon, Hyun-Kyu,Choi, Seong-Dae 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.1
In this paper, a new nano/micro-mechanical processing test machine was developed. This new test machine, which is based on the principle of the scanning force controlled probe microscope, can realize nano/micro-mechanical machining and in-process profile measurement. Experimental results of nano/micro indentation and scratching show that the controllable cutting depth of the test machine can be controlled by PZT actuator. Profile measurement of the machined surface has also been performed by using the test machine and a conventional AFM(Atomic Force Microscopy). A good agreement of the two measurement results have been achieved.
원자간력 현미경의 캔틸레버의 정량적 특성평가를 위한 계측 시스템 개발
권현규(Hyun-Kyu Kweon),남기호(Ki-Ho Nam) 한국기계가공학회 2007 한국기계가공학회지 Vol.6 No.2
In this study, the two methods of stiffness measurement(Spring constant) of cantilever were proposed for quantitative measurement in Atomic Force Microscopy(AFM). As the 1st method for the measurement of stiffness, the probe method, which is used in the measurement of the semiconductor mechanical and electrical properties, was applied to the measurement of the cantilever. Experiments by the probe method were performed finding the resistance value of cantilever. As the results, the resistance was measured differently along with the dimension and the thickness of cantilever that determined the stiffness(spring constant) of the lever. As the 2nd method, the vibration characteristics(Dunkerley expression) is used to obtain the stiffness of the complex structure which is combined by AFM cantilever and the standard cantilever. We measured the resonant frequency from the complex structure using the micro stages and stereo microscope. As the results, we confirmed that the vibration characteristics(Dunkerley expression) is effected the micro complex structure of AFM cantilever.
Development of Micro/Nano Universal Testing Machine using a Piezoelectric Ceramic Actuator
권현규(Hyun Kyu Kweon),최성대(Seong Dae Choi) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.4
Micro/nano MUTM(Miniature Universal Testing Machines) are becoming increasingly popular for testing the mechanical properties of MEMS materials, metal thin films, and micro-molecule materials. And new miniature testing machines that can perform in-process measurement in SEM, TEM, and SPM are also needed. In this paper, new micro/nano MUTMs with a precision positioning system that can be used in SEM, TEM, and SPM have been proposed. Three type precision actuators are used in fine positioning system. One is the bimorph type PZT actuator, and the another is the multilayer type(inchworm) and the other is the nano motor. Coarse positioning is implemented by step motor. The size, load output, and displacement output of bimorph type MUTM are respectively 109×64×22(㎜), about 35g, and 0.4 ㎜. Multilayer type MUTM has the size of 60×46×27(㎜) and load output of 0.5 ㎏. And the displacement output is controlled with the block digital form. The results of the analysis and basic properties of the three types positioning system, and micro/nano MUTMs are presented in this paper. In addition, the experiment results of in-process measurement during tensile load in SEM and AFM are showed, too.
권현규(Hyun-Kyu Kweon),박창용(Chang-Yong Park) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.2
This paper presents a new stopper mechanism for precision stage by using the Piezoelectric element actuator. The new stage including a new stopper mechanism has the precision positioning mechanism that was been developed for generation displacements with nanometer accuracy and a millimeter dynamic range simulataneouly. The stage is composed not of the mechanical two stopper but of only one Piezoelectric element actuator. The characteristics for the new stage and the stopper have been evaluated experimentally. As the results, we can know that the linearity error characteristics of stage is 30nm in the 20㎛ measurement range. In addition, the experimental results are confirmed the possibility of the movement in millimeter range.
PSD의 출력특성향상을 위한 경사 입력광의 특성해석에 대한 기본연구
권현규(Hyun-Kyu Kweon),박창용(Chang-Yong Park) 한국기계가공학회 2010 한국기계가공학회지 Vol.9 No.4
In this paper, the output characteristics of PSD(Position Sensetive Detector) used in measurement system are described. Most of the precision measurment systems are accomplished by a laser diode(LD), a photo diode(PD) and PSD(Position Sensetive Detector), which are used in reflection of mirror or projection of infrared spectrometer. But it is especially restricted by resolution of PD and PSD in nano-measurement. A new inclined light methods into the PSD are employed in the surface measurement system for increasing the resolution. As the results, we can know that the output characteristics of detective senser (PSD) become more than 2 or 3 times by changing inclined angle(range: 5 degree) compared with common angle. In addition, the experiment results are confirmed that the change of inclined angle is not affecting to the linearity and repeating.
유니몰프 PZT 액츄에이터를 이용한 정밀 이송기구의 개발
권현규(Hyun-Kyu Kweon),최성대(Sung-Dae Choi) 한국기계가공학회 2008 한국기계가공학회지 Vol.7 No.1
This paper presents a new precision moving instrument for the displacement and direction control using the uni-morph type PZT actuator. The instrument is composed of the two-body and a link. The body has the uni-morph type PZT actuator, which make the vibration. Movement of simple moving instrument is generally analyzed by the theory of center-of-gravity moment. However the analysis of the instrument in this paper is focused the resonance of instrument. Resonance of the body is originated a uni-morph type PZT actuator that is vibrated by voltage and frequency. The basic performances of one body instrument are analyzed by the FEM analysis. And experiments are also performed to confirm the linear movement of the instrument and direction control. it is proper a voltage control than a frequency control for the direction changing. And Moving velocity is 0.032㎧.
정선환,최성대,권현규,최은환,Cheong, Seon-Hwan,Choi, Seong-Dae,Kweon, Hyun-Kyu,Choi, Eun-Hwan 한국기계가공학회 2004 한국기계가공학회지 Vol.3 No.2
Generally industrial multi-articulated robots are used for parts assembly, welding, and painting processes. The high flexibility of them is very useful to not only parts assembly, welding, and painting processes, but also machining processes. But because of machining processes to need a high stiffness of machine structure, so machining is usually not tried at them, except deburring processes now. During past three years the works are carried out to improve the stiffness of a industrial multi-articulated robot With some gas spring as a first idea in this research area. As a result of that stiffness was significantly up, and found and investigated the machining possibility at it.
정선환,최성대,권현규,최은환,Cheong, Seon-Hwan,Choi, Seong-Dae,Kweon, Hyun-Kyu,Choi, Eun-Hwan 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.4
The stiffness of multi-articulated industrial robots is very weak, because their structure is an articulated type with some links and joints. Thus it is known that cutting processes for metals are not accepted in machine shop well, but they have a lot of merits for cutting processes, for example, drilling, tapping, and engraving etc, because of the characteristics of their high degree of freedom. The temptation of cutting aluminium was carried out to investigate the feasibility and the limitations or constraints for cutting metals on them. First the mode shapes of 6 degree of freedom welding robot were taken and analysed, and next the cutting processes were practically carried out on it. The results of study were found out to show the feasibility of cutting processes at drilling under 6mm of tool diameter, as well as to have some limitations and constraints, for examples, feed rate, depth of cut and cutting force etc.