• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.1054-1058
• /
• 1995

There have been many research works for the indirect cutting force measurement in machining process, which deal with the case of one-axis cutting process. In multi-axis cutting process, the main difficulties to estimate the cutting forces occur when the feed direction is reversed. This paper presents the indirect cutting force measurement method in contour NC milling processes by using current signals of servo motors. An artificial neural network (ANN) system are suggested. An artificial neural network(ANN) system is also implemented with a training set of experimental cutting data to measure cutting force indirectly. The input variables of the ANN system are the motor currents and the feedrates of x and y-axis servo motors, and output variable is the cutting force of each axis. A series of experimental works on the circular interpolated contour milling process with the path of a complete circle has been performed. It is concluded that by comparing the ANN system with a dynamometer measuring cutting force directil, the ANN system has a good performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.780-785
• /
• 2001

A method for accurate measurement of the contact force in the current collection system of the high-speed railway is developed. In order to measure the contact force with minimal modifications to the pantograph, strain gauges are attached to the bottom of the contact strip. An algorithm for deriving the magnitude and stagger of the contact force from the bending strain measurements is devised. For the sample pantograph, the static contact forces are measured to within ${\pm}$5 % error for the magnitude and ${\pm}$ 2cm error for the stagger. For dynamic contact force measurement, it is found that the contact strip can the regarded as a rigid body for the contact frequency of less than 15 ㎐.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.3
• /
• pp.27-32
• /
• 2002

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.237-240
• /
• 2003

In biological cell manipulation, manual thrust or penetration of an injection pipette into an embryo cell is currently performed by a skilled operator, relying on visual feedback information only. Accurately measuring cellular forces is a requirement for minimally invasive cell injections. Moreover, the cellular farce sensing is essential in investigating the biophysical properties for cell injury and membrane modeling studies. This paper presents cellular force measurements for the force feedback-based biomanipulation. Cellular force measurement system using piezoelectric polymer sensor is implemented to measure the penetration force of a zebrafish egg cell. First, measurement system setup and calibration are described. Second, the force feedback-based biomanipulation is experimentally carried out. Experimental results show that it successfully supplies real-time cellular force feedback to the operator at several tens of uN and thus plays a main role in improving the reliability of biological cell injection tasks.

• Journal of Sensor Science and Technology
• /
• v.23 no.6
• /
• pp.357-361
• /
• 2014

This paper describes the evaluation of the effectiveness of rehabilitation therapy for patients with finger paralysis based on a two-finger force measurement system (TFFMS). The paralyzed fingers can be recovered through rehabilitation therapies. The finger pressing force of the patients can be measured utilizing the TFFMS previously developed by the author [7]. The TFFMS, however, has not been fully adopted as a standard method for evaluating the therapy owing to the lack of a standard protocol. The pressing force of healthy volunteers and patients is analyzed with the TFFMS to explore the feasibility of the TFFMS as an evaluation device. The test confirms that the established standard protocol is useful to quantitatively assess the progress of finger rehabilitation therapy.

• Korean Journal of Applied Biomechanics
• /
• v.22 no.2
• /
• pp.243-251
• /
• 2012

The purpose of this study was to develop an impact force measurement device in order to facilitate the acquisition of quantitative data for the analysis of various sporting events. The device was designed to include cylindrical aluminum supports of 220 mm diameter, which allows mounting and dismounting of the device on walls and frames. In addition, a hard sponge for impact absorption, as well as 4 springs, were attached to the plate. Both were attached to prevent psychological variables and injuries. When a subject applies force on the device, accurate data about the maximum repulsive force is acquired in real time, with a lag of only 0.001 s. The device was calibrated in four steps: (1) increase, (2) increase, (3) increase-decrease, and (4) increase-decrease. The maximum relative expanded uncertainty was 0.166%, indicating that the impact force measurement was sufficiently reliable. The proposed device can be applied to various sporting situations and is expected to be useful for studying kinetics.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1996.10a
• /
• pp.158-162
• /
• 1996

A split shaft device is commonly used to measure the radial force of lip seals. The radial force measured with this device includes some inevitable error. This error is caused by the fact that the split shafts cannot maintain a perfect circle when the interference becomes larger or smaller than some initial interference. In this study, a theoretical model for the calculation of the radial contact force has been carried out, and an explicit equation for the measurement error as a function of the initial interference and the interference to be measured has been obtained. The error when the interference is small is not dependent upon the material properties and the shape of the lip seal, but rather upon the amplitude of the initial interference and the interference to be measured. When the interference is larger or smaller than the initial interference, the measured contact force is always underestimated or overestimated.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.3
• /
• pp.22-29
• /
• 2004

Runout causes severe differences among cutting force waveforms due to changes of rotational radii. Thus a runout model must be included in a cutting force model to simulate cutting force accurately. In this paper, a runout modeling method and a measurement method using a dialgauge were developed, which were easy to apply. To calculate runout parameters, a computer program algorithm which obtained runout parameters from measurement values was developed. Cutting force waveforms simulated from cutting force model considering runout effect and measured from experiments had good agreements for their wave size and order.

• International Journal of Precision Engineering and Manufacturing
• /
• v.9 no.3
• /
• pp.46-50
• /
• 2008

The present status and future prospects of the levitation mass method (LMM), a technique for precision mass and force measurement, are reviewed. In the LMM, the inertial force of a mass levitated using a pneumatic linear bearing is used as the reference force applied to the objects being tested, such as force transducers, materials, or structures. The inertial force of the levitated mass is measured using an optical interferometer. We have modified this technique for dynamic force calibration of impact, oscillation, and step loads. We have also applied the LMM to material testing, providing methods for evaluating material viscoelasticity under an oscillating or impact load, evaluating material friction, evaluating the biomechanics of a human hand, and generating and measuring micro-Newton-level forces.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.564-567
• /
• 1997

In the design of structure the forces acting on the structure are important parameter for noise and vibration control. However, in the complex structure, the forces at the injection point on the structure cannot be measured directly. Thus it is necessary to find out indirect force evaluation method. In this paper forces have been measured with in-situ vibration responses and system information. Three existing techniques of indirect force measurement, viz. direct inverse, principal component analysis and regularization have been compared. It has been shown that multi-vibration responses are essential for the precise estimation of the forces. To satisfy those conditions, Rotary compressor is adopted as test sample, because it is very difficult to measure the injection forces from internal excitation to shell. It has also been obtained that relatively higher force is transmitted though three welding paths to the compressor shell. It shows a good agreement between direct and indirect force evaluation with curvature shell and plate and is investigated the possibility of force evaluation of rotary compressor as a complex structure.