• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.422-428
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• 2005

In this paper, the contact force between two colliding bodies is modeled by using Hertz's force-displacement law and nonlinear damping function. In order to verify the appropriateness of the proposed contact force model, the drop type impact test is carried out for different impact velocities and different materials of the impacting body, such as rubber, plastic and steel. In the drop type impact experiment, six photo interrupters in series close to the collision location are installed to measure the velocity before impact more accurately. The characteristics of contact force model are investigated through experiments. The parameters of the contact force model are estimated using the optimization technique. Finally the estimated parameters are used to predict the impact force between two colliding bodies in opening action of the magnetic contactor, a kind of switch mechanism for switching electric circuits.

• ETRI Journal
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• v.32 no.5
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• pp.722-728
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• 2010

This paper presents the design and fabrication model of a touchpad based on a contact-resistance-type force sensor. The touchpad works as a touch input device, which can sense contact location and contact force simultaneously. The touchpad is 40 mm wide and 40 mm long. The touchpad is fabricated by using a simple screen printing technique. The contact location is evaluated by the calibration setup, which has a load cell and three-axis stages. The location error is approximately 4 mm with respect to x-axis and y-axis directions. The force response of the fabricated touchpad is obtained at three points by loading and unloading of the probe. The touchpad can detect loads from 0 N to 2 N. The touchpad shows a hysteresis error rate of about 11% and uniformity error rate of about 3%.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.278-284
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• 1998

In order to measure the real contact force between head and disk on hard disk drive quantitatively, many technique of measurement have been developed. Acoustic Emission Sensor can be used for detect elastic energy of head/disk contact as arms value. In this study using pencil breaking test is proposed for finding contact force using transfer function between calibrated force and real contact force. And real AE data of subambient and tripad slider shows bending and torsional mode and their energy are dominant in hard disk and head contact.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.101-107
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• 2003

A new mechanical probe for 3-D feature measurement on coordinate measuring machines (CMMs) is presented. The probe is composed of the contact stylus and the three-component force sensor. With the stylus mounted on the force sensor, the probe can not only measure 3-D features, but also detect contact force acting on the stylus tip. Furthermore, the probing direction and the actual contact position can be determined by the relationship among three components of contact force to be detected. In this paper, transformation matrix representing the relationship between the external force acting on the stylus tip and the output voltages of measurement gauges is derived and calibrated. The prototype of probe is developed and its availability is investigated through the experimental setup for calibration test of the probe. A series of experimental results show that the proposed probe can be an effective means of improving the accuracy of touch probing on CMM.

• Journal of Surface Science and Engineering
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• v.35 no.2
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• pp.129-137
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• 2002

The purpose of solderability assessment is to predict the effectiveness of soldering process. It is important for companies pursuing zero defects manufacturing because poor solderability is the major cause of two third of soldering failures. The most versatile solderability method is wetting balance method. However, there exist so many indices for wettability in the wetting balance test e.g. time to reach 2/3 values of maximum wetting force, tine to reach zero wetting force, maximum withdrawal force. In this study, three solderability assessment methods, which were the maximum withdrawal force, the wetting balance and the dynamic contact angle (DCA), were evaluated by comparing each other. The wetting balance technique measures the solderability by recording the forces exerted from the specimen after being dipped into the molten solder. Then the force at equilibrium state can be used to calculate a contact angle, which is known as static contact angles. The DCA measures contact angles occurred during advancing and withdrawing of the specimen and the contact angles are known as dynamic contact angles. The maximum withdrawal force uses the maximum force during withdrawal movement and then a contact angle can be calculated. In this study, the maximum withdrawal force method was found to be an objective index for measuring the solderability and the experiment results indicated good agreement between the maximum withdrawal force and the wetting balance method.

• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.409-419
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• 2013

A T-stub connection with high-strength bolts under tensile force is affected by prying action force and the contact force, among others, between members. If a design equation that does not consider such prying action force and contact force between members is not proposed, the T-stub under tensile force is liable to be fractured under the strength lower than the estimated design strength. To prevent it, many studies have proposed contact force estimation equations between members as well as the prying action force of the T-stub connection with high-strength bolts. However, no design equations based on such research have been proposed in South Korea. Therefore, this study aims to propose an estimation model for more accurate prying action force and contact force, and improve on previously proposed estimation models by implementing the three-dimensional, nonlinear finite element analysis. Throughout the results of three-dimensional, nonlinear finite element analysis, the prediction model proposed in this research for the prying action force and contact force of a T-stub provided much more accurate estimation than that of a existing prediction model previously suggested.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1262-1265
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• 2004

A cycloidal speed reducer is a type of the speed reducers of machinery. The cycloidal speed reducer consists of two cycloidal plate gears, housing roller gear, input shaft, output pin and shaft, and eccentric bearings. Especially the cycloidal plate gear has the peculiar parts of the teeth, because of gearing with the housing roller gear that has the several rollers on the circular line. And then all teeth on the cycloidal plate gear can be designed to contact with the rollers on the housing roller gear at the same time. Therefore the cycloidal plate gear has always contact motion with rollers and the force is interacted between roller gear with cycloidal plate gear. Because the contact force and friction force must be required to improve the accuracy in design procedures of cycloidal speed reducers, this paper presents a force analysis considered friction effect approach derived by static force equilibrium condition, geometrical adaptation, instant velocity center method and relative velocity method.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1374-1378
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• 2005

Appropriate upward force is crucial for the pantograph on high speed train to collect current from the catenery system without separation. However, at high speed, large aerodynamic lifting force is generated by the contact plate and the arms of pantograph, which may cause wear of the contact wire. In this study, to confirm the interface performance of the pantograph on Korea High Speed Train, a method to measure the contact force of the pantograph was proposed and the related measurement system was developed. The forces acting on the pantograph were clarified and a procedure to calculate the aerodynamic lifting force was proposed. A special device was invented and applied to measure the lifting force. Measured contact forces were displayed by the developed system and evaluated according to the criteria. Countermeasures were also taken to reduce the contact force based on the results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.21-26
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• 2016

This study evaluates the magnitudes and distributions of contact tangential forces with the swaging depth of punch acting at the contact surfaces between a rotor core slot and a Cu bar during a sequential rotor core swaging process. The effects of the core slot shape on the magnitudes and distributions of the total contact forces were investigated to improve the productivity of the rotor core swaging process. Parametric elastic-plastic numerical analyses were performed using simplified two-dimensional cyclic symmetric plane strain models to evaluate the contact force distributions at the contact surfaces. The numerical analysis results show that the total contact tangential forces increased by about 55% with the adjacent Cu bar swaging process. The length of the core slot is a dominant factor in the core slot design as result of the increased total contact tangential forces during the swaging process of the rotor core.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.1080-1084
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• 1989

The motion of an workpiece to be manipulated is determined by the forces applied to the workpiece. During the contact between the robot hand and the workpiece, impulsive forces may dominate all other forces, and determine the ultimate success or failure of a task. Therefore, one of the important problems in the robot hands is the control of the initial impact force. In this paper, the problem of the force control of robot hand under system with contact force is presented. The principle of energy can be applied in the modelling of the impact force. In order to achieve stable contact and avoid bounces and vibrations, VSS is adopted in the design of the contact force controller. Some simulations are carried out for a pushing operation to control the contact force.