• Journal of Mechanical Science and Technology
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• v.16 no.3
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• pp.310-319
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• 2002

This paper deals with the analytical modeling, and the experimental verification of the strain rate self-sensing method using a hybrid adaptive filter for a cantilevered piezoelectric beam. The piezoelectric beam consists of two laminated lead zirconium titanates (PZT) on a metal shim. A mathematical model of the beam dynamics is derived by Hamilton's principle and the accuracy of the modeling is verified through the comparison with experimental results. For the strain rate estimation of the cantilevered piezoelectric beam, a self-sensing mechanism using a hybrid adaptive filter is considered. The discrete parts of this mechanism are realized by the DS1103 DSP board manufactured by dSPACE$\^$TM/. The efficacy of this method is investigated through the comparison of experimental results with the predictions from the derived analytical model.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.594-607
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• 2013

A new efficient analytical eye-diagram determination technique for coupled interconnect lines is presented. Two coupled lines are decoupled into isolated eigen modes; bit blocks for coupled lines, which are defined as a block of consecutive bits, are then represented with decoupled modes. The crosstalk effects within the bit blocks are taken into account. Thereby, the crucial input bit patterns for the worst case eye-diagram determination are modeled mathematically, including inter-symbol interference (ISI). The proposed technique shows excellent agreement with the SPICE-based simulation. Furthermore, it is very computation-time-efficient in the order of magnitude, compared with the SPICE simulation, which requires numerous pseudo-random bit sequence (PRBS) input signals.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.492-500
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• 2002

This paper presents a study of the effect of varying the roll gap of oval pass in round-oval-round pass sequence on the interracial slip of workpiece, entrance and exit velocities, stresses and roll load that the workpiece experiences during rolling, by applying analytical method, finite element simulation and verification through hot bar rolling tests. The results have shown that the roll gap variation of oval pass affects the interfacial slip of workpiece along the groove contact and the specific roll pressure. The optimum conditions in terms of minimum interfacial slip and minimum specific roll pressure, which might influence the maximum groove life, is obtained when the subsequent round pass is completely filled.

• International Journal of Fluid Machinery and Systems
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• v.6 no.4
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• pp.189-199
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• 2013

A practical method of surge simulation in a system of a high-pressure-ratio multistage axial flow compressor and ducts, named SRGTRAN, is described about the principal procedures and the details. The code is constructed on the basis of one-dimensional stage-by-stage modeling and application of fundamental equations of mass, momentum, and energy. An example of analytical result on surge behaviors is included as an experimental verification. It will enable to examine the transient flow phenomena caused by possible compressor surges and their influences on the system components in plant systems including high-pressure-ratio axial compressors or gas turbines.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1031-1032
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• 2007

In order to reduce the cogging torque, by predicting the variation of the cogging torque according to pole arc/pitch ratio by analytical and FE methods, pole arc/pitch ratio which makes the cogging torque minimum are determined. And then, the measurements of cogging torque for permanent magnet generators with determined pole arc/pitch ratio are presented. The reasons for the error between predicted and measured value are discussed fully in terms of the shape of permanent magnet. Finally, by confirming that predicted results for cogging torque according to pole arc/pitch ratio and skew are shown in good agreement with those obtained from measured one, the validation of analysis results is confirmed.

• Journal of Drive and Control
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• v.12 no.2
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• pp.39-48
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• 2015

In order to control the actuators of hydraulic machinery such as excavators, various control valves are typically assembled in a single block. Such a control block is called a main control valve(MCV). In this paper, we analyzed the working principle and the particular purpose of the design of all valves included in the MCV system. To Examine the reliability of the analysis model, the pressure drop of the MCV at each port was measured. The authors developed an analytical model of the control valve(main spool, load poppet, pressure relief, make up, and regeneration). The authors considered the notch shape of the spool while developing the analytical models of the main spool valve. Most importantly, at the stage before the analysis model was applied in the design tuning, the reliability was ensured by comparing the analysis results with the test results. This paper showed a process of developing an analysis model that can be utilized in the design and tuning stages.

• Journal of Drive and Control
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• v.15 no.2
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• pp.22-31
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• 2018

This study deals with verifying the design feasibility, of an independently driving hydraulic system for disaster response purposes, through an analytical approach. The development target is a system in which four traveling motors are driven independently, and must be easy to operate even under conditions in which different loads are applied to the traveling motors. In order to be suitable for complex work, the hydraulic system was designed using the main control valve with a pressure compensation function. If we can develop an analytical model that reflects the specifications and functions of the parts through the analysis program, we can verify the validity of the design before we make the prototype. The purpose of this study therefore, is to verify the feasibility of designing an independent drive hydraulic system through the development of an analysis model from the viewpoint of complex work. The analysis program uses Simulation X.

• Structural Engineering and Mechanics
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• v.17 no.5
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• pp.641-654
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• 2004

This paper presents a theoretic model of a smart structure, a transversely isotropic piezoelectric thick square plate constructed with three laminas, piezoelectric-elastic-piezoelectric layer, by adopting the first order shear deformation plate theory and piezoelectric theory. This model assumes that the transverse displacements through thickness are linear, and the in-plane displacements in the mid-plane of the plate are not taken to be account. By using Fourier's series expansion, an exact Navier typed analytical solution for deflection and electric potential of the simply supported smart plate is obtained. The electric boundary conditions are being grounded along four vertical edges. The external voltage and non-external voltage applied on the surfaces of piezoelectric layers are all considered. The convergence of the present approach is carefully studied. Comparison studies are also made for verifying the accuracy and the applicability of the present method. Then some new results of the electric potentials and displacements are provided. Numerical results show that the electrostatic voltage is approximately linear in the thickness direction, while parabolic in the plate in-plane directions, for both the deflection and the electric voltage. These results are very useful for distributed sensing and finite element verification.

• Tribology and Lubricants
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• v.40 no.1
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• pp.1-7
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• 2024

Ball bearings are a major component of mechanical parts for transmitting rotation. Compared to tapered roller bearings, ball bearings offer less rolling resistance, which leads to reduced heat generation during operation. Because of these characteristics, ball bearings are widely used in electric vehicles and machine tools. The design of ball bearing cages has recently emerged as a major issue in ball bearing design. Cage design requires pre-verification of performance using theoretical or experimental formula or computational fluid dynamics (CFD). However, CFD analysis is time-consuming, making it difficult to apply in case studies for design decisions and is mainly used in performance prediction following design confirmation. To use CFD in the early stages of design, main-taining analytical accuracy while reducing the time required for analysis are necessary. Accordingly, this study proposes a laminar steady-state segment CFD technique to solve the problem of long CFD analytical times and to enable the use of CFD analysis in the early stages of design. To verify the reliability of the CFD analysis, a bearing drag torque test is performed, and the results are compared with the analytical results. The proposed laminar steady-state segment CFD technique is expected to be useful for case studies in bearing design, including cage design.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.456-461
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• 2011

Recently the design specification has been advanced with preventing earthquake disaster in Korea because of increasing occurrence of large size earthquake. A composite plate with ductile fiber is proposed, which can enhance the performance of built tunnel in both strength and ductility. This study is to focus to verify the effect of strengthening of existing tunnels which is built without earthquake type load scenario, so that it can provide the safety of existing urban subway system against earthquakes.