• Tunnel and Underground Space
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• 제18권6호
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• pp.436-446
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• 2008

The volumetric expansion ratio of rock mass on the subsidence occurrence area can explain why the depth of the surface subsidence is lower than the height of an opening; it is because the empty space of the gangway is filled with the broken rock. But, until now, when the surface subsidence mechanism is studied without consideration of the volumetric expansion ratio, it is usually overlooked that the amount of subsidence occurrence can be overestimated. Therefore, in this study, the authors researched the subsidence occurrence mechanism with a new theoretical approaching method. The volumetric expansion ratio obtained from this method has been applied to the numerical simulations. The authors adopted the UDEC(Universal Distinct Element Code) for their discontinuum numerical analysis, because this program has an advantage for analyzing the behavior of rock discontinuities.

• Agricultural and Biosystems Engineering
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• 제2권2호
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• pp.63-68
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• 2001

The objective of this study was to develop a real-time soil moisture meter using RF impedance. The impedance suchas capacitance and resistance (or conductance) was analyzed using parallel cylinder type capacitance probe(C-probe) and Q-meter (HP4342). The capacitance and conductance of soil increased as volumetric water content increased. The 5 MHz of modified Colpitts type crystal oscillator was designed to detect the capacitance change of the C-probe with moist soil. A third order polynomial regression model was proposed to describe the relationship between RF impedance and volumetric water content. The prototype real time moisture meter consisted of the C-probe, sample container, oscillator, frequency counter and related signal processing units. The calibration equation for measurement of volumetric moisture content of soil was developed and validated. The correlation coefficient and root mean square error between measured volumetric water content by oven method and predicted values by prototype moisture meter for unknown soil samples were 0.984 and 0.032$cm^3$$cm\^3$, respectively.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제8권3호
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• pp.28-34
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• 1999

The objective of this study is to estimate and to compensate far the volumetric error of a workpiece influenced by the geometric error of a machine tool. In this paper, the volumetric error is defined and the error synthesis model is presented. Then, the volumetric error of workpiece is calculated and compared through the simulation, and a new tool-path is generated to compensate for the error in the post-processor of CAM system using the error synthesis model. By this method, the error is compensated without modification or replacement of a machine tool being in use.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.134-139
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• 1998

The objective of this study is to estimate and to compensate for the volumetric error of a machine tool. In this paper, the volumetric error is defined and error synthesis model is presented. Then, the volumetric error of workpiece is compared through the virtual machining and a new tool-path is generated to compensate for the error in the post-processor of CAM system using the error synthesis model. By this method, the error is compensated without modification or replacement of a machine tool being in use.

• 유공압시스템학회:학술대회논문집
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• 유공압시스템학회 2010년도 춘계학술대회
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• pp.39-43
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• 2010

It is hard and complex to analytically derive a volumetric displacement formula of a gerotor hydraulic motor because geometric shape of its rotors is complicate. An analytical method about the volumetric displacement is proposed in this work, which is relatively easy and based upon two physical concepts. The first one is energy conservation between hydraulic input energy of the motor and mechanical output energy. The second concept is torque equilibrium with respect to inner and outer rotors. The proposed formula about the volumetric displacement is verified by comparing an analytical displacement and a numerical displacement for an example specification of the motor. The numerical displacement is calculated through a kind of CAD technology. The analytical formula can be utilized in analysis and design of hydraulic gerotor motors.

• Journal of Power System Engineering
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• 제9권3호
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• pp.26-32
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• 2005

The volumetric efficiency is significantly affected by the behavior of pressure wave in induction system and exhaust pipe. By the motion of the piston, there exist pressure fluctuation in induction system which produce waves. Waves are propagated along a pipe bi-directional as they propagated through it, making compression wave and rare-faction(expansion) wave. These wave phenomena can affect to the volumetric efficiency. As a method of improvement of the volumetric efficiency, fuel economy and pollutant emission reduction particularly in low engine speeds, a side-branch additional tunable helmholtz resonator on the secondary pipe of intake system is proposed by use of their acoustic vibrations. Some of results are presented which deal with their physical phenomena for the wave action of intake system in a four-stroke three cylinders diesel engine.

• Journal of Information Processing Systems
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• 제8권1호
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• pp.55-66
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• 2012

This paper presents a dual modeling method that simulates the graphic and haptic behavior of a volumetric deformable object and conveys the behavior to a human operator. Although conventional modeling methods (a mass-spring model and a finite element method) are suitable for the real-time computation of an object's deformation, it is not easy to compute the haptic behavior of a volumetric deformable object with the conventional modeling method in real-time (within a 1kHz) due to a computational burden. Previously, we proposed a fast volume haptic rendering method based on the S-chain model that can compute the deformation of a volumetric non-rigid object and its haptic feedback in real-time. When the S-chain model represents the object, the haptic feeling is realistic, whereas the graphical results of the deformed shape look linear. In order to improve the graphic and haptic behavior at the same time, we propose a dual modeling framework in which a volumetric haptic model and a surface graphical model coexist. In order to inspect the graphic and haptic behavior of objects represented by the proposed dual model, experiments are conducted with volumetric objects consisting of about 20,000 nodes at a haptic update rate of 1000Hz and a graphic update rate of 30Hz. We also conduct human factor studies to show that the haptic and graphic behavior from our model is realistic. Our experiments verify that our model provides a realistic haptic and graphic feeling to users in real-time.

• Transactions of the Korean Society of Machine Tool Engineers
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• 제15권1호
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• pp.1-7
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• 2006

A method of the volumetric error measurement and calibration of NC machine tools is studied using an artifact method. In this study, a hole-pate is designed and machined using stainless steel. We tested and applied the hole-plate artifact in a commercial CMM(Coordinate Measuring Machine), after calibration of the hole-plate using a precise CMM. It has been shown that not only the measurement of geometric error components but also the 2D length error calculation in a working volume is available using the hole-pate artifact method. The results of study can also be used in NC machine with touch probe as the same method in CMM.

• Tunnel and Underground Space
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• 제15권2호
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• pp.137-144
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• 2005

An estimation technique of the joint diameter distribution using the least square method is suggested. When utilizing the technique by Song and Lee, the diameter distribution would be obtained only from the trace length distribution defined in an infinite window after the trace length distribution is estimated from the contained trace length distribution. With the new technique, however, the diameter distribution can be directly obtained from the sample histogram of the contained trace lengths. Compared with the previous technique, it shows a more accurate result for small sizes of joint samples and provides the joint geometry parameter of volumetric frequency. Verification of this new technique was completed by using Monte Carlo simulations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제11권3호
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• pp.48-54
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• 2012

This paper introduces the kinematic calibration method to improve the positioning accuracy of a parallel mechanism. Since all the actuators in the parallel mechanism are controlled simultaneously toward the target position, the volumetric errors originated from each motion element are too complicated. Therefore, the exact evaluation of the error sources of each motion element and its calibration is very important in terms of volumetric errors. In the calibration processes, the measurement of the errors between commands and trajectories is necessary in advance. To do this, a digitizer was used for the data acquisition in 3 dimensional space rather than arbitrary planar error data. After that, the optimization process that was used for reducing the motion errors were followed. Consequently, Levenberg-Marquart algorithm as well as the error data acquisition method turned out effective for the purpose of the calibration of the parallel mechanism.