• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.980-983
• /
• 1996

This paper presents the method of determining state feedback gains of XPTOS for disk drive servomechanism based BESSEL filter prototype. A typical disk drive actuator can be modeled as second order dynamics for low frequencies. However, the response at higher frequencies shows resonant behavior which cannot be easily modeled. XPTOS consists of the nonlinear control region and the linear control region. In the linear control region, the poles of a second order nominal model of plant must be properly relocated by pole placement technique to attenuate resonant modes at high frequency and to attain minimum time state transition. It is difficult to select position to satisfy this object because velocity feedback gain is subjected to position feedback gain in XPTOS. Here poles of BESSEL filter prototype are selected to determine state feedback gains of XPTOS. Simulation results for disk drive servomechanism using XPTOS having state feedback gains by the proposed method are presented.

• Structural Monitoring and Maintenance
• /
• v.6 no.2
• /
• pp.85-101
• /
• 2019

The effects of foundation scour depth and riverbed condition on the natural frequencies of a typical cross-river integral abutment bridge have been studied. The conventional operational modal analysis technique has been employed in order to extract the modal properties of the bridge and the results have been used in the Finite Element (FE) model updating procedure. Two tests have been carried out in two different levels of water and wet condition of the riverbed. In the first test, the riverbed was in dry condition for two subsequent years and the level of water was 10 meter lower than the natural riverbed. In the second test, the river was opened to water flow from the upstream dam and the level of water was 2 meter higher than the natural riverbed. The results of these two tests have also been used in order to find to what extend the presence of water flow in the river and saturation of the surrounding soil affect the bridge natural frequencies. Finally, the updated FE model of the bridge has been applied in a series of parametric analyses incorporating the effect of piles' relative scour depth on the bridge natural frequency of the first four vibration modes.

• Journal of Theoretical and Applied Mechanics
• /
• v.2 no.1
• /
• pp.1-14
• /
• 1996

In this paper, breaking waves are generated in a 2-D wave tank and simulated by using a higher-order boundary element method. A piston-type wavemaker is operated by signals composed of elementary waves. The phase of elementary waves is determined by the linear theory such that they are focused to a prescribed position. Calculated plunging waves coincide well with experiment. A steel box with different plate thicknesses is installed at a predetermined position in the tank. Measured impulsive pressures due to breaking waves are found to be 0.8-1.2$\rho$C2, where $\rho$ corresponds to water density and C to wave celerity. The transverse displacement of the plate is described in terms of modal eigenfunctions. The natural frequencies measured by impact tests in air for thin plate coincide with the computational and theoretical values. The radiationpotential due to plate vibration is derived and the radiation force is expressed in terms of hydroelastic added mass and damping forces. Comparison of natural frequencies of plate in water proves that hydroelastic added mass and damping are properly considered. The measured strain due to regular waves supports the calculated one, but there are apparent discrepancies between theory and experiment in the impulsive case.

• Structural Engineering and Mechanics
• /
• v.69 no.2
• /
• pp.231-241
• /
• 2019

In this paper, a new higher order shear deformation model is developed for static and free vibration analysis of functionally graded beams with considering porosities that may possibly occur inside the functionally graded materials (FGMs) during their fabrication. Different patterns of porosity distributions (including even and uneven distribution patterns, and the logarithmic-uneven pattern) are considered. In addition, the effect of different micromechanical models on the bending and free vibration response of these beams is studied. Various micromechanical models are used to evaluate the mechanical characteristics of the FG beams whose properties vary continuously across the thickness according to a simple power law. Based on the present higher-order shear deformation model, the equations of motion are derived from Hamilton's principle. Navier type solution method was used to obtain displacement, stresses and frequencies, and the numerical results are compared with those available in the literature. A comprehensive parametric study is carried out to assess the effects of volume fraction index, porosity fraction index, micromechanical models, mode numbers, and geometry on the bending and natural frequencies of imperfect FG beams.

• Proceedings of the KIEE Conference
• /
• 1987.07a
• /
• pp.110-114
• /
• 1987

A method for synthesizing low-pass elliptic filters in a microstrip configuration is presented. The realization consists of the cascade connection of proper rectangular elements, each one corresponding to four reactive elements of the lumped-constant prototype. This allows an effictive control of parasitics and unwanted reactances. Which results in the possibility of realizing higher order filters with cutoff frequencies UP to X-band. Fifth and seventh order filters were fabricated on allumina substrates.

• Steel and Composite Structures
• /
• v.35 no.5
• /
• pp.659-670
• /
• 2020

This paper proposes the use of a porous core between layers of laminated composite plates to examine its effect on the natural frequencies of the resulted porous laminated composite sandwich plate (PLCSP) resting on a two-parameter elastic foundation. Moreover, it has been suggested that the dispersion of porosity has two different functionally graded (FG) patterns which are compared with a uniformly dispersed (UD) profile to find their best vibrational efficiency in the proposed PLCSPs. In FG patterns, two types of dispersions, including symmetric (FG-S) and asymmetric (FG-A) patterns have been considered. To derive the governing Eigen value equation of such structures, the first order shear deformation theory (FSDT) of plates has been employed. Accordingly, a finite element method (FEM) is developed to solve the derived Eigen value equation. Using the mentioned theory and method, the effects of porosity parameters, fiber orientation of laminated composite, geometrical dimensions, boundary conditions and elastic foundation on the natural frequencies of the proposed PLCSPs have been studied. It is observed that embedding porosity in core layer leads to a significant improvement in the natural frequencies of PLCSPs. Moreover, the natural frequencies of PLCSPs with FG porous core are higher than those with UD porous core.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.28A no.11
• /
• pp.866-873
• /
• 1991

In this paper the electric and magnetic field distributions in a TEM cell used for EMC testing are analyzed numerically. The fields are distorted with the increase of frequency. These distortions are due to higher order modes and resonances and cause the bandwidthe limitations in the uae of TEM cels. The upper frequency is lower modes however, are reflected at some points through the tapered ends of the cell. Higher order modes however, are reflected at some points within the tapered region where it becomes too small to support the modes, The first two TE mode(TE$_{01}$ and TE$_{10}$) cutoff frequencies and the first six TE$_mnp$ resonant ferquencies are identified in a TEM cell (1x0 6x2m,w=0.72m) from field patterns and the results are consistent with others' data. The circumferential wall currents to support resonances are shown. For the large cell it is desired to extend the usable frequency range above the cutoff frequency of the first higher order mode. This study proposes an attempt to expand the frequency bandwidth by a resonance suppression.

• Journal of Korean Academy of Nursing
• /
• v.35 no.6
• /
• pp.979-990
• /
• 2005

Purpose: The purpose of this study was to develop and to apply the NANDA, NOC, and NIC (NNN) linkages into a computerized nursing process program using the classification systems of nursing diagnoses, nursing outcomes and nursing interventions. Method: The program was developed with planning, analysis, design and performance stages. The program was applied to 117 patients who were admitted to orthopedic surgery nursing units from January to February, 2004. Results: Thirty-five of fifty-three nursing diagnoses were identified. Five nursing diagnoses in order of frequency were: Acute pain $(28.4\%)$, Impaired physical mobility $(15.6\%)$, Impaired walking $(8.7\%)$, Chronic pain $(5.5\%)$ and Risk for disuse syndrome $(5.0\%)$. The nursing outcomes of the 'Acute pain' nursing diagnosis tended to have higher frequencies (cumulative) in order of Pain management $(95.2\%)$, Comfort level $(35.5\%)$ and Pain level $(17.7\%)$. The nursing interventions of the 'Acute pain' nursing diagnosis tended to have higher frequencies (cumulative) in order of Pain management $(71.0\%)$, Splinting $(24.2\%)$ and Analgesic administration $(17.7\%)$. In comparison of outcome indicator scores between before and after the intervention according to the 61 nursing outcomes, the mean scores of 52 outcome indicators after the intervention were significantly higher than before the intervention. Conclusion: It is expected that this program will help nurses perform their nursing processes more efficiently.

• Journal of Korean Society of Steel Construction
• /
• v.14 no.1
• /
• pp.1-12
• /
• 2002

To obtain more accurate responses of laminated composite structures, the effect of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate need to be considered in the analysis. The improved higher-order theory is used to determine the deflections and natural frequencies of laminated composite structures. A quasi-elastic method is used for the solution of viscoelastic analysis of the laminated composite plates and sandwiches. Solutions of simply-supported laminated composite plates and sandwiches are obtained and the results are compared with those by the 3D elasticity theory and other theories. The improved theory proposed in this paper is shown to predict the deflections and natural frequencies more accurately than all other theories.

• Smart Structures and Systems
• /
• v.21 no.3
• /
• pp.279-286
• /
• 2018

The free longitudinal vibration of a circular truncated nanocone is investigated based on the nonlocal elasticity theory. Exact analytical formulations for tapered nanostructures are derived and the nonlinear differential governing equation of motion is developed. The nonlocal small scale effect unavailable in classical continuum theory is addressed to reveal the long-range interaction of atoms implicated in nonlocal constitutive relation. Unlike most previous studies applying the truncation method to the infinite higher-order differential equation, this paper aims to consider all higher-order terms to show the overall nonlocality. The explicit solution of nonlocal stress for longitudinal deformation is determined and it is an infinite series incorporating the classical stress derived in classical mechanics of materials and the infinite higher-order derivative of longitudinal displacement. Subsequently, the first three modes natural frequencies are calculated numerically and the significant effects of nonlocal small scale and vertex angle on natural frequencies are examined. The coupling phenomenon of natural frequency is observed and it is induced by the combined effects of nonlocal small scale and vertex angle. The critical value of nonlocal small scale is defined, and after that a new proposal for determining the range of nonlocal small scale is put forward since the principle of choosing the nonlocal small scale is still unclear at present. Additionally, two different types of nonlocal effects, namely the nonlocal stiffness weakening and strengthening, reversed phenomena existing in nanostructures are observed and verified. Hence the opposite nonlocal effects are resolved again clearly. The nano-engineers dealing with a circular truncated nanocone-based sensors and oscillators may benefit from the present work.