• Structural Monitoring and Maintenance
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• 제5권1호
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• pp.93-110
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• 2018

In order to provide a novel strategy for long-span bridge health monitoring system design, this paper proposes a novel ultimate bearing capacity ratios based bridge internal force monitoring design method. The bridge ultimate bearing capacity analysis theories are briefly described. Then, based on the ultimate bearing capacity of the structural component, the component ultimate bearing capacity ratio, the uniformity of ultimate bearing capacity ratio, and the reference of component ultimate bearing capacity ratio are defined. Based on the defined indices, the high bearing components can then be found, and the internal force monitoring system can be designed. Finally, the proposed method is applied to the bridge health monitoring system design of the second highway bridge of Wuhu Yangtze river. Through the ultimate bearing capacity analysis of the bridge in eight load conditions, the high bearing components are found based on the proposed method. The bridge internal force monitoring system is then preliminary designed. The results show that the proposed method can provide quantitative criteria for sensors layout. The monitoring components based on the proposed method are consistent with the actual failure process of the bridge, and can reduce the monitoring of low bearing components. For the second highway bridge of Wuhu Yangtze river, only 59 components are designed to be monitored their internal forces. Therefore, the bridge internal force monitoring system based on the ultimate bearing capacity ratio can decrease the number of monitored components and the cost of the whole monitoring system.

• 한국공작기계학회논문집
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• 제10권1호
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• pp.1-9
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• 2001

The development of flexible automation in the manufacturing industry is concerned with production activities performed by unmanned machining system A major topic relevant to metal-cutting operations is monitoring toll wear, which affects process efficiency and product quality, and implementing automatic toll replacements. In this paper, the measurement of the cutting force components has been found to provide a method for an in-process detection of tool wear. The static com-ponents of cutting force have been used to detect flank wear. To eliminate the influence of variations in cutting conditions, tools, and workpiece materials, the force modeling is performed for various cutting conditions. The normalized force dis-parities are defined in this paper, and the relationships between normalized disparity and flank were are established. Final-ly, artificial neural network is used to learn these relationships and detect tool wear. According to proposed method, the static force components could provide the effective means to detect flank wear for varying cutting conditions in turning operation.

• 반도체디스플레이기술학회지
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• 제7권1호
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• pp.17-22
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• 2008

The proposed hybrid controller consists of PID controller, feedforward controller and RLSE (Recursive Least Square Estimating) adaptive controller to compensate the force ripple that is periodic function of position in a linear motor. The modeling of force ripple is divided into the current-dependent and current-independent components. The current independent components never change as the current into the linear motor changes. On the other hand, the current-dependent components change as current varies when the velocity and load of the linear motor change. The proposed controller can compensate both force ripples. The feedforward controller compensates the current-independent components and the RLSE adaptive controller compensates the current-dependents components. We verified the performance of the controller by simulation and experiments.

• 한국지진공학회논문집
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• 제24권6호
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• pp.267-275
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• 2020

In the event of an earthquake, non-structural components require seismic performance to ensure evacuation routes and to protect lives from falling non-structural components. Accordingly, the seismic design code proposes horizontal force for the design and evaluation of non-structural components. Ground motion observed on each floor is affected by a building's eigen vibration mode. Therefore, the earthquake damage of non-structural components is determined by the characteristics of the non-structural component system and the vibration characteristics of the building. Floor response spectra in the seismic design code are estimated through time history analysis using seismic waves. However, it is difficult to use floor response spectra as a design criterion because of user-specific uncertainties of time history analysis. In addition, considering the response characteristics of high-rise buildings to long-period ground motions, the safety factor of the proposed horizontal force may be low. Therefore, this study carried out the horizontal force review proposed in the seismic design code through dynamic analysis and evaluated the floor response of seismic waves considering buildings and predominant periods of seismic waves.

• 한국정밀공학회지
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• 제5권1호
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• pp.84-93
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• 1988

The on-line detection of the chip flow is one of the most important technologies in com- pletly automatic operation of machine tool, such as FMS and Unmanned Factories. This problem has been studied by many researchers, however, it is not solved as yet. For the recognition of chip flow in this study, the dynamic cutting force components due to the chip breaking were measured by dynamometer of piezo-electric type, and the frequency components of cutting force were also analyzed. From the measured results, the effect of cutting conditions and tool geometry on the dynamic cutting force component and chip formation were investigated in addition to the relationships between frequency of chip breaking (fB) and side serrated crack (fC) of chip. As a result, the following conclusions were obtaianed. 1) The chip formations have a large effect on the dynamic cutting force components. When chip breaking takes place, the dynamic cutting force component greatly increases, and the peridoic components appear, which correspond to maximum peak- frequency. 2) The crater wear of tool has a good effect on the chip control causing the chiup to be formed as upward-curl shape. In this case, the dymamic cutting force component greatly increases also 3) fB and fC of chip are closely corelated, and fC of chips has a large effect on the change of the situation of chip flow and dynamic cutting force component. 4) Under wide cutting conditions, the limit value (1.0 kgf) of dynamic cutting force component exists between the broken and continuous chips. Accordingly, this value is suitable for recognition of chip flow in on-line control of the cutting process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.371-376
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• 1996

The damping force of shock absorber in an automobile is determined by the components which construct the S/A. In this study we investigate the individual effect of these components on damping force. In addition, opening of important valve doling compression and tension cycle due to up-down reciprocation movement is also researched. Thus we are to strictly control the properties and tolerance of components having important effects on tile damping force and to produce S/A of better quality.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.552-555
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• 1996

In this paper, we present a force control of a five-axes robot, using an impedance model. Tasks such as assembly, grinding, and deburring, which involve extensive contact with the environment, are better handled by controlling the forces of interaction between the manipulator and the environment. The five-link articulated robot is equipped with a wrist force sensor which consists of an array of strain gauges and can delineate the three components of the vector force along the three axes of the sensor coordinate frame, and the three components of the torque about these axes. For the precise control of the contact force, impedance models of a robot and the environment are defined. Experimental results are shown.

• 센서학회지
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• 제28권2호
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• pp.106-112
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• 2019

Flexible impact force sensors composed of piezoelectric PZT/PDMS composite sandwiched between Al/PET films were fabricated and their voltage signal characteristics were evaluated under varying impact forces for electronic mitt applications. The piezoelectric impact force sensor on an ethylene-vinyl acetate (EVA) substrate exhibited an output voltage difference of no greater than 40 mV a periodical impact test in with the impact load was increased by as much as 240 N by a restoration time of 5 s in a five-time experiment, implying good sensing ability. Moreover, the impact force sensor embedded four electronic mitts showed a reliable sensitivity of less than 1 mV/N and good repeatability under 100 N-impact force during a cycle test executed 10,000 times. This indicated that the fabricated flexible piezoelectric impact sensor could be used in electronic mitt applications. However, the relatively low elastic limit of substrate material such as EVA or poly-urethane slightly deteriorated the sensitivity of the impact sensor embedded electronic mitt at over 200 N-impact forces.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1379-1382
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• 2007

In this paper, we present a simplified analytic approach for the prediction of roll force to be applicable to the grooveless rolling. The approach is based on the deformation shape deduced from physical considerations and employs the assumption that the deformation homogeneously occurs in three directions. Strain and strain rate are calculated by the geometric relationships between those components and the prescribed deformation functions. Then, stress components are obtained from the Levy-Mises' flow rule. By integrating the stress components along the rolling direction, roll force are finally obtained. The prediction accuracy of the proposed model is examined through comparison with results obtained from the finite element analysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.814-817
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• 2000

This paper has two purposes. One is to investigate the effect of the helix angle of endmilling cutter on the cutting haracteristics of inconel 718 in down endmilling. To this end a newly developed cutting force model in down end milling process is presented. Using this cutting force components of 4-tooth endmills with various helix angles have been predicted. Predicted values of cutting force components are well coincide with the measured ones. The other is to compare the down endmilling characteristics of lnconel 718 with those of the up milling previously presented. In up endmilling as the helix angle becomes larger the radial and tangential components of the specific cutting force ($K_1 and K_r$) decrease. While in down milling $K_1 and K_r$ become smaller as the helix angle decrease.