• 한국정밀공학회지
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• 제14권11호
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• pp.93-101
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• 1997

Ever since the nonlinearity of machine tool dynamics was established, researchers attempted to make use of this fact to devise better monitoring, diagnostics and control system, which were hitherto based on linear models. Theory of chaos which explains many nonlinear phenomena comes handy for furthering the analysis using nonlinear model. In this study, measuring system will be constructed using multi-sensor (Tool Dynamometer, Acoustic Emission) in end milling process. Then, it will be verified that cutting force is low-dimensional chaos by calculating Lyapunov exponents. Fractal dimension, embedding dimension. And it will be investigated that the relation between characteristic parameter calculated from sensor signal and tool wear.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.13-14
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• 2006

The quality of tool material is very important factor in machining evaluation. The characteristics of tungsten carbide, such as grain size and hardness, and density are depending on the variation of Co composition and WC size. In this study, the non-coated end mill which is made of ultra-fine tungsten carbide is investigated by measuring tool wear and tool lift test. The machining test is conducted with high hardened workpiece under high-speed cutting condition.

• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.3-8
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• 2007

A machining system that generates accurate relative motions between the tool and workpiece is required to realize ultra precise machining or measurements. Accuracy improvements for each element of the machine are also required. This paper proposes a machining system that uses a compensation device for the six-degree-of-freedom (6-DOF) motion error between the tool and workpiece. The compensation device eliminates elastic and thermal errors of the joints and links due to temperature fluctuations and external forces. A hexapod parallel kinematics mechanism installed between the tool spindle and surface plate is passively actuated by a conventional machine. Then the parallel mechanism measures the 6-DOF motions. We describe the conception and fundamentals of the system and test a passively extensible strut with a compensation device for the joint errors.

• 로봇학회논문지
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• 제13권4호
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• pp.205-212
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• 2018

This paper deals with the paddle type end of arm tool for rescue robot instead of rescue worker in dangerous environments such as fire, earthquake, national disaster and defense. It is equipped at the dual arm manipulator of the rescue robot to safely lift up an injured person. It consists of the paddle for lifting person, sensors for detecting insertion of person onto the paddle, sensor for measuring the tilting angle of the paddle, and mechanical compliance part for preventing incidental injuries. The electronics is comprised of the DAQ module to acquire the sensors data, the control module to treat the sensors data and to manage the errors, and the communication module to transmit the sensors data. After optimally designing the mechanical and electronical parts, we successfully made the paddle type end of arm tool and evaluated its performance by using specially designed jigs. The developed paddle type end of arm tool is going to be applied to the rescue robot for performance verification through field testing.

• 대한인간공학회지
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• 제14권1호
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• pp.69-81
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• 1995

Few studies on the biomechanical analysis of hand postures and tool handling tasks exist because of the lack of appropriate measurement techniques for hand force. A measurement system for the finger forces and joint angles for the analysis of manual tool handling tasks was developed in this study. The measurement system consists of a force sensing glove made from twelve Force Sensitive Resistors and an angle-measuring glove (Cyberglove$^{TM}$, Virtual technologies) with eighteem joint angle sensors. A biomechanical model of the hand using the data from the measurement system was also developed. Systems of computerized procedures were implemented inte- grating the hand posture measurement system, biomechanical analysis system, and the task analysis system for manual tool handling tasks. The measurement system was useful in providing the hand force data needed for an existing task analysis system used in CTD risk evaluation. It is expected that the hand posture measurement developed in this study will provide an efficient and cost-effective solution to task analysis of manual tool handling tasks.s.

• 한국공작기계학회논문집
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• 제11권5호
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• pp.73-80
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• 2002

In this study, work materials of the ree form surface shape was machined by ball end mill cutter according to the change of cutting location and depth, and the acquired data of cutting force, tool deflection and shape accuracy were analyzed. Cutting force results were obtained with tool dynamometer and tool deflection values were measured by a couple of eddy-current sensors. Shape accuracy was obtained by roundness tester and surface profile measuring machine. As inclination angle was decreased, cutting force was increased. Cutting force showed large value at $105^{\circ}$ and $150^{\circ}$. Tool deflection was less at down milling than at up milling, decreased at 45$^{\circ}$ and 120$^{\circ}$, and shown large tool deflection at $150^{\circ}$. Roughness values were found to be bad in the inside of surface shape tool deflection. Surface accuracy was obtained better precision in down milling than in up milling.

• 성인간호학회지
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• 제28권1호
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• pp.95-105
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• 2016

Purpose: This study was conducted to test whether Health Communication Assessment Tool (HCAT) developed by Campbell et al. in 2013 can be applied to assess Korean nursing students' communication skills in simulation education. Methods: The content validity of the Korean version of HCAT (K-HCAT) was evaluated through expert's assessment and a principal component analysis was conducted for testing construct validity. The convergent validity was tested by measuring relationship between the K-HCAT and those of existing communication assessment tool for standardized patient instruction. The evaluation was done by surveying 154 senior students from four different nursing colleges. Results: The K-HCAT was condensed into 15 items from the original 22 HCAT items. Four factors were extracted from the principal component analysis; factor loadings ranged from .50 to .83; cumulative explained variance was 62.65%. Four factors were entitled as 'relationship building', 'empowering', 'empathy/response', and 'education/feedback'. Cronbach's ${\alpha}$ for sub-dimensions ranged from .73 to .84. An evaluation of convergent validity showed that the scores of the K-HCAT were moderately correlated with those of an assessment tool for standardized patient instruction. Conclusion: The K-HCAT can be used as an effective tool for assessing nursing students' communication skills in various kinds of simulation educations Further research is needed to test the consistency of the K-HCAT.

• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.54-58
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• 2007

This paper describes an atomic force microscope (AFM)-based instrument for measuring the nanoscale cutting edge profiles of diamond cutting tools. The instrument consists of a combined AFM unit and an optical sensor to align the AFM tip with the top of the diamond cutting tool edge over a submicron range. In the optical sensor, a aser beam is emitted from a laser diode along the Y-axis and focused to a small beam spot with a diameter of approximately $10{\mu}m$ at the beam waist, which is then received by a photodiode. The top of the tool edge is first brought into the center of the beam waist by adjusting it in the X-Z-plane while monitoring the variation in the photodiode output. The cutting tool is then withdrawn and its top edge position at the beam center is recorded. The AFM tip can also be positioned at the beam center in a similar manner to align it with the top of the cutting edge. To reduce electronic noise interference on the photodiode output and thereby enhance the alignment accuracy, a technique is applied that can modulate the photodiode output to an AC signal by driving the laser diode with a sinusoidal current. Alignment experiments and edge profile measurements of a diamond cutting tool were carried out to verify the performance of the proposed system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.621-628
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• 2000

A kinematic ball bar measuring system can analyze the various errors of a machine tool easil rapidly with only one measurement, But it cannot be used to measure the errors of the equipment the semiconductor manufacturing (e.g. chip mounter, PCB router etc.) not to use a cir interpolation. This paper presents the method to apply a kinematic ball bar measuring system tc machines which use merely a linear interpolation Also, the work of measuring and calibratir various errors of a chip mounter with a kinematic bal1 bar measurement system is accomplished

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.613-617
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• 2000

This paper descries the effect of the stylus tip size on the measuring error in surface topography measurement. To analyze the distortional effect of an actual surface geometry originating from the finite stylus size, the surface is modeled as a sinusoid and the stylus tip as a circle. the measuring error is defined as the ratio of the standard deviation of a tracing profile and an original profile. It is shown that this measuring error depends on the amplitude and wavelength of an original profile. In this paper, the spectrum analysis is applied to investigate the distortional effect due to the mechanical filtering of the stylus in the frequency domain. and, the cumulative power spectrum is applied to determinate the minimum wavelength limits to be measured with the various stylus tip radius from these results, a new method to select proper stylus tip radius is proposed.