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이준석(Lee Junsok),곽윤근(Kwak Yoonkeun),김수현(Kim Soohyun) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
In this paper, we proposed a new method to control the length of carbon nano tube in the single CNT<br/> probe. A single CNT probe was composed of a tungsten tip made by the electrochemical etching and carbon<br/> nano tube which was grown by CVD and prepared through the sonication. The two components were attached<br/> with the carbon tape. Since the length of CNT can not be controlled during the manufacturing, the post<br/> process is needed to shorten the CNT. In this paper, we proposed the method of electrochemical process. The<br/> process was done under the optical microscope and the results were checked by SEM. The diameter of the<br/> carbon nano tube used in this paper was about 130 because the above process had to be done with the<br/> optical microscope. Using the method proposed in this paper, we can control the length of the nano tube tip.
단분자 위치추적을 위한 원형 스캐닝 타입의 공초점 형광 현미경 설계
박효준(Hyojun Park),곽윤근(Yoonkeun Kwak),김수현(Soohyun Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Single molecule tracking technique has been widely used for studying biophysical processes, such as the diffusion of protein in cell membrane or the movement of molecular motors. A method to measure the position change of fluorescing single particles designed for a confocal fluorescence microscope. This method can be used to measure relative distance on the scale of 10nm with 1ms temporal resolution. By moving around the excitation beam in a circular orbit, photons emitted by fluorescence molecules are detected. The fluorescence signal depends on the relative position of the fluorescent molecule with respect to the circle of rotation. After each rotation, the center of rotation is moved to new position so that single molecule tracking can be achieved.
자기예압 공기베어링 스테이지의 3 자유도 운동오차 측정 및 능동 보정
노승국(Seung-Kook Ro),김수현(Soohyun Kim),곽윤근(Yoonkeun Kwak),박천홍(Chun Hong Park) Korean Society for Precision Engineering 2009 한국정밀공학회지 Vol.26 No.2
This paper presents a linear air bearing stage with compensated motion errors by active control of preloads generated by magnetic actuators with combination of permanent and electro-magnets. A 1-axis linear stage motorized with a linear motor with 240 mm of travel range is built for verifying this design concept and tested its performances. The three motions of the table are controlled with four magnetic actuators driven by current amplifiers and a DSP based digital controller. Three motion errors were measured combined method with laser interferometer and two-probe method with 0.085 um of repeatability for straightness error. The measured motion errors were modeled as functions of the stage position, and compensation were carried out with feedforward control because the characteristics of the motion control with magnetic actuators are linear and independent for each degree-of-freedoms. As the results, the errors were reduced from 1.09 um to 0.11 um for the vertical motion, from 9.42 sec to 0.18 sec for the pitch motion and from 2.42 sec to 0.18 sec for roll motion.
이준석(Junsok Lee),권순근(Soongeun Kwon),곽윤근(Yoonkeun Kwak),김수현(Soohyun Kim) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.6
In this paper, we proposed a new method to control the length of carbon nanotube using electrochemical etching. We made a nano probe that was composed of the tungsten tip and multi-wall carbon nanotube. The nano probe was placed on the nano stage and the carbon nanotube on the nano probe was etched in the electrolyte solution with the applied voltage. The overall procedures were done under optical microscope and can be monitored. We can obtain a nano probe with proper length through this procedure.
초정밀 직선 이송계용 능동 자기예압 공기베어링에 관한 연구
노승국(Seung-Kook Ro),김수현(Soohyun Kim),곽윤근(Yoonkeun Kwak),박천홍(Chun Hong Park) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.6
In this paper, we propose a precise linear motion stage supported by magnetically preloaded air bearings. The eight aero static bearings with rectangular carbon porous pads were located only one side of vertical direction under the platen where four bearings are in both sides of horizontal direction as wrap-around-design, and this gives simpler configuration than which constrained by air bearings for all direction. Each of the magnetic actuators has a permanent magnet generating static magnetic flux for required preload and a coil to perturb the magnetic force resulting adjustment of air¬bearing clearance. The characteristics of porous aero static bearing are analyzed by numerical analysis, and analytic magnetic circuit model is driven for magnetic actuator to calculate preload and variation of force due to current. A l-axis linear stage motorized with a core less linear motor and a linear encoder was designed and built to verify this design concept. The load capacity, stiffness and preload force were examined and compared with analysis. With the active magnetic preloading actuators controlled with DSP board and PWM power amplifiers, the active on-line adjusting tests about the vertical, pitching and rolling motion were performed. It was shown that motion control for three DOF motions were linear and independent after calibration of the control gains.
노승국(Seung-Kook Ro),김수현(Soohyun Kim),곽윤근(Yoonkeun Kwak),박천홍(Chun Hong Park) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.12
In this paper, we proposed an air bearing stage with active magnetic preloads in vertical directions compensating motion errors and attenuating vibrations to improve dynamic characteristics. This preloaded design gives simpler configuration of the stage, and active control of preload can be used for compensating motion errors by feedforward method. To improve dynamic characteristics, vibration of the table is monitored by an accelerometer, and controlled by a DSP based digital controller with integrator and band pass filters for suppressing roll and pitch vibration modes. The modes were evaluated by measuring frequency response functions, and compared with compensated responses. This showed effective results for suppressing poorly damped regenerative vibration of air bearings.
생물학적 초미세력 검출을 위한 탄소나노튜브 프로브의 제작 및 기계적 특성 검출
권순근(Soongeun Kwon),박효준(Hyojun Park),이형우(Hyung Woo Lee),곽윤근(Yoonkeun Kwak),김수현(Soohyun Kim) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.5
In this study, a carbon nanotube probe (CNT probe) is proposed as a mechanical force transducer for the measurement of pico-Newton (pN) order force in biological applications. In order to measure nantube's displacement in the air or liquid environment ,the fabrication of a CNT probe with tip-specific loading of fluorescent dyes is performed using tip-specific functionalization of the nanotube and chemical bonding between dyes and nanotube. Also, we experimentally investigated the mechanical properties of the CNT probe using electrostatic actuation and fluorescence microscope measurement. Using fluorescence measurement of the tip deflection according to the applied voltage, we optimized the bending stiffness of the CNT probe, therefore determined the spring constant of the CNT probe. The results show that the spring constant of CNT probes is as small as 1 pN/㎚ and CNT probes can be used to measure pN order force.
이준석(Lee Junsok),최재성(Choi Jaiseong),강경수(Kang Gyungsoo),곽윤근(Kwak Yoonkeun),김수현(Kim Soohyun) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
In this paper, we propose a method to estimate the actuating voltage of the nanotweezer made by manual assembly using carbon nanotube. The nanotweezer is composed of two CNT arms that are made by the multiwalled carbon nanotube and tungsten tip. Since the each CNT arm has the macro actuator, the nanotweezer can manipulate a large particle and it is possible to close and open the CNT arm repeatedly. The closing voltage, i.e., actuating voltage is calculated using the capacitance between the carbon nanotubes in CNT arm. We demonstrate the actuation of the nanotweezer using the voltage calculated with the electrostatic force.
단일 CNT 팁에서 탄소나노튜브의 에칭부피에 관한 연구
이준석(Lee Junsok),최재성(Choi Jaiseong),강경수(Kang Gyungsoo),곽윤근(Kwak Yoonkeun),김수현(Kim Soohyun) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Because of the various length condition of carbon nanotube, it is very confined the application area of the single CNT tip. In this paper, it was proposed the cutting technique of single CNT tip and the relationship between the etched volume and the amount of the applied charge. It is possible to control the length of single CNT tip arbitrary using this technique. The etched volume and length in the single CNT tip can be predicted with the amount of the applied charge. It is very easy to make a single CNT tip with proper length using this technique and to make nanotweezer that was composed two single CNT tips.