• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.645-646
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• 2006

The oscillation amplitude of a probe tip is an important parameter to determine the resolution of atomic force microscopy (AFM) techniques. In this work, we introduce a new method for the measurement of the oscillation amplitude of a quartz tuning fork tip sub-nanometer resolution.

• Safety and Health at Work
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• 제7권4호
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• pp.347-353
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• 2016

Background: This study aimed to investigate the relation between key strike forces and musculoskeletal symptoms (MSS). Moreover, this study presents a key strike force measurement method to be used in a workplace setting. The correlation between key strike force characteristics and MSS was previously studied, but the measurement methods used either a single-key switch or force platforms applied under the keyboard. Most of the studies were conducted in a laboratory setting. The uniqueness of measurement methods in the current study is their ability to measure forces applied to a specific key in a workplace setting and to provide more information about specific key strike forces during typing. Methods: Twenty-four healthy computer workers were recruited for the study. The demographic questionnaire, and self-reported questionnaires for psychosocial status (General Nordic Questionnaire for Psychological and Social Factors at Work) and for detecting MSS were filled up, which later helped in dividing the participants into two groups (12 participants with pain and 12 without pain). Participants typed a predetermined text that utilized the instrumented keys multiple times. The dynamic forces applied to the keys were recorded and collected, using four thin and flexible force sensors attached to the preselected keys according to their location. Results: The results demonstrated that participants with high levels of MSS, specifically in the back and neck, in the last year exerted significantly higher key strike forces than those with lower levels of symptoms (p < 0.005). Conclusion: The key strike force exerted while typing on a keyboard may be a risk factor for MSS, and should therefore be considered in ergonomic evaluations and interventional programs.

• 한국기계가공학회지
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• 제3권2호
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• pp.53-59
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• 2004

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.

• 한국항공우주학회지
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• 제48권7호
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• pp.489-495
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• 2020

충격파 터널에서 항력 측정을 위하여 가속도계 기반 시스템을 설계 및 구축하고, 마하 6 유동조건에서 원뿔형 모델의 항력계수를 측정하였다. 항력 측정 시스템의 마찰력을 보정하기 위하여 간단하고 직관적인 교정 방식을 제시하고, 항력 측정 결과를 단순 원뿔형 모델의 전산유체역학 해석 결과와 비교, 분석하였다. 다양한 형상의 지지대를 이용하여 지지대에 의한 항력 측정 간섭 영향을 파악하고 이를 최소화하기 위한 디자인을 제시하였다. 수정된 지지대를 이용하여 항력계수를 측정한 결과, 지지대에 의한 항력계수 오차가 작아지는 것이 확인되었다.

• Tribology and Lubricants
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• 제29권2호
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• pp.91-97
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• 2013

Quantifying the nanoscale force between the atomic force microscopy (AFM) probe of a force-sensing cantilever and the sample is one of the challenges faced by AFM researchers. The normal force calibration is straightforward; however, the lateral force is complicated due to the twisting motion of the cantilever. Force measurement in a liquid environment is often needed for biological applications; however, calibrating the force of the AFM probes for those applications is more difficult owing to the limitations of conventional calibration methods. In this work, an accurate nondestructive lateral force calibration method using multiple pivot loading was proposed for liquid environment. The torque sensitivity at the location of the integrated probe was extrapolated based on accurately measured torque sensitivities across the cantilever width along a few cantilever lengths. The uncertainty of the torque sensitivity at the location of the integrated tip was about 13%, which is significantly smaller than those for other calibration methods in a liquid environment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.128.5-128
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• 2001

This paper presents investigation of an arc force sensor for a robotic welding control system. Arc force sensor is employed in this research to monitor the bead geometry of the arc welding process. Arc force sensor mounted at the end of the robot wrist was employed to measure the arc force applied to the weld. Experimental configuration for measurement of arc force was used to quantify the changes in the arc force distributions of the plate being welded. A relationship between the bead dimension and the arc force distributions was established. The sensor information was used to establish a relationship between welding current and arc force. Arc force sensor have shown to be one of the most sophisticated technique to monitor perturbations that occurred during robotic arc welding process.

• 한국정밀공학회지
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• 제22권4호
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• pp.84-91
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• 2005

We measured the pitch of one-dimensional (ID) grating specimens using a metrological atomic force microscope (M-AFM). The ID grating specimens a.e often used as a magnification standard in nano-metrology, such as scanning probe microscopy (SPM) and scanning electron microscopy (SEM). Thus, we need to certify the pitch of grating specimens fur the meter-traceability in nano-metrology. To this end, an M-AFM was setup at KRISS. The M-AFM consists of a commercial AFM head module, a two-axis flexure hinge type nanoscanner with built-in capacitive sensors, and a two-axis heterodyne interferometer to establish the meter-traceability directly. Two kinds of ID grating specimens, each with the nominal pitch of 288 nm and 700 nm, were measured. The uncertainty in pitch measurement was evaluated according to Guide to the Expression of Uncertainty in Measurement. The pitch was calculated from 9 line scan profiles obtained at different positions with 100 ㎛ scan range. The expanded uncertainties (k = 2) in pitch measurement were 0.10 nm and 0.30 nm for the specimens with the nominal pitch of 288 nm and 700 nm. The measured pitch values were compared with those obtained using an optical diffractometer, and agreed within the range of the expanded uncertainty of pitch measurement. We also discussed the effect of averaging in the measurement of mean pitch using M-AFM and main components of uncertainty.

• 한국강구조학회 논문집
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• 제25권1호
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• pp.61-70
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• 2013

인장구조물의 하중을 지지하는 인장재 사이에서 한쪽은 왼나사, 다른 쪽은 오른나사로 구성되어 장력을 조절하는 장치가 턴버클이다. 인장재의 종류 및 연결 형태에 따라 다양한 종류가 존재하지만, 보편적으로 사용되는 기존의 턴버클은 장력을 측정할 수 없는 단점을 지니고 있다. 이에 장력조절의 기능과 함께 장력측정도 가능한 측정용 턴버클을 개발하였다. 본 논문에서는 기 개발된 측정용 턴버클의 비선형해석을 통한 극한강도와 측정 신뢰성을 확인하고자 한다. 기 개발된 100kN, 200kN, 300kN급 측정한계하중을 가지는 턴버클의 극한강도를 살펴보면, 측정한계하중의 5배 이상의 극한강도를 나타내었다. 추가로 300kN 이상의 고장력을 측정하기 위한 턴버클 개발을 위하여 검토한 결과 턴버클의 경사부가 휨과 인장에 저항하기 때문에 크기가 거대해지는 경향이 나타났다. 이에 300kN급 턴버클을 병렬연결하여 설치를 하면 600kN까지 측정할 수 있을 것이라는 발상에서 병렬연결장치를 구상하여 실험을 실시하였고, 그 가능성을 실험결과로부터 확인할 수 있었다. 또한 실험적인 인장구조물을 설치하여 개발된 턴버클이 외기에 노출되었을 시에 초기 하중의 변화 및 부식의 정도를 살펴보았다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.34-38
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• 1996

Cylindrical plunge grinding is widely used for final machining process of precision parts such as automobile, aircraft, measurement units. In order to make parts which have high precison accuracy and high surface integrity, it is neccessary to consider grinding characteristics. these grinding characteristics are closely related grinding force. Soin this study, to examine closely characteristics of grinding force, effects of dressing condition, depth of cut and speed ratio on grinding force are considered. As the result, It is shown that grinding forces are affected bydressing condition, depth of cut and speed ratio and that there exist threshod grinding force and it also affected by dressing conditon.

• 대한기계학회논문집A
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• 제26권3호
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• pp.537-543
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• 2002

This paper examines a new in-process measurement system for the measurement of micro-defects on the surfaces of brittle materials by using the AFM (Atomic Force Microscopy). A new AFM scanning stage that can also perform nano-scale bending of the sample was developed by adding a bending unit to a commercially available AFM scanner. The bending unit consists of a PZT actuator and sample holder, and can perform static and cyclic three-point bending. The true bending displacement of the bending unit is approximately 1.8mm when 80 volts are applied to the PZT actuator. The frequency response of the bending unit and the stress on the sample were also analyzed, both theoretically and experimentally. Potential surface defects of the sample were successfully detected by this measurement system. It was confirmed that the number of micro-defects on a scratched surface increases when the surface is subjected to a cyclic bending load.