• 대한기계학회논문집A
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• 제24권11호
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• pp.2672-2679
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• 2000

In synthesizing and RSSS-SC mechanism that is the kinematic model of the McPherson strut suspension system in automobiles, the design equations for R-S, S-S and S-C dyads should be solved separately for a given set of prescribed positions. The number of prescribed positions that the RSSS-SC mechanism can be synthesized is up to three because of the S-C dyad. This limitation may cause unsatisfactory results in synthesized joint positions. This paper presents a kinematic synthesis method to place the joints of an RSSS-SC mechanism in desired boundaries by varying the prescribed positions of the mechanism within acceptable tolerances. The sensitivity analysis of the joint positions is used determine which displacement parameter should be altered to fulfill this task.

• Journal of Mechanical Science and Technology
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• 제16권1호
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• pp.102-108
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• 2002

Numerical simulations of 1, 2 dichloroethane(EDC) pyrolyisis are conducted to understand the process in the production of the vinyl chloride monomer (VCM) and by-products. A chemical kinetic mechanism Is developed, with the adopted scheme involving 44 gas-phase species and 260 elementary forward and backward reactions. Detailed sensitivity analyses and the rates of production analysis are performed on each of the reactions and the various species, respectively. The concentrations of EDC, VCM, and HCI predicted by this mechanism are in good agreement with those deduced from experiments of commercial and laboratory scale. The mechanism is found to accurately predict the EDC yield an(1 the production of by-products by varying the ranges of pyrolysis temperature, residence time, and pressure which impact on the pyrolysis of 1, 2 dichloroethane. The influence of reactions related to H atom on the relative sensitivity of EDC becomes important as the residence time increases. The pyrolysis of EDC mainly occurs through C$_2$H$_4$Cl$_2$+Cl=CH$_2$CICHI+HCI.

• 대한기계학회논문집
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• 제19권8호
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• pp.1822-1831
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• 1995

A general formulation of the design optimization problem with the random parameters is presented here. The formulation is based on the stochastic finite element second-order perturbation method ; it takes into full account of the stress and displacement constraints together with the rates of change of the random variables. A method of direct differentiation for calculating the sensitivity coefficients in regard to the governing equation and the second-order perturbed equation is derived. A gradient-based nonlinear programming technique is used to solve the problem. The numerical results are specifically noted, where the stiffness parameter and external load are treated as random variables.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1271-1280
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• 2000

A sensor placement technique to identify structural parameter was developed. Experimental results must be acquired to identify unknown dynamic characteristics of a targeting structure for the comparison between analytical model and real structure. If the experimental environment was not equipped itself properly, it can be happened that some valuable information are distorted or ill-condition can be occurred. In this work the index to determine exciting points was derived from the criterion of maximizing parameter sensitivity matrix and that to choose measurement points was from that of preserving the invariant of sensitivity matrix. This idea was applied to a compressor hull structure to verify its performance. The result shows that the selection of measurement and excitation points using suggested criteria improve the ill-conditioning problem of inverse type problems such , as model updating.

• 대한기계학회논문집A
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• 제23권11호
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• pp.1896-1903
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• 1999

The basic requirements to improve the joints quality of tube-to-tubesheet for heat exchangers are to obtain high residual contact pressures between the tubes and the tubesheet as well as low residual stresses in the transition zone of the tubes. The residual contact pressures and residual stresses which govern the joint quality are influenced by parameters such as material properties, geometric dimension of tube and tubesheet and expansion pressures. There are two types of tube layout patterns, triangular and square, which are frequently used for heat exchangers. The purpose of the present work is to examine the superior tube layout patterns considering the joints quality by comparing numerical results from sensitivity analyses which were performed for both of tube layout patterns.

• 대한기계학회논문집A
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• 제33권11호
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• pp.1341-1346
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• 2009

In this paper, the technique to reinforce the durability performance of structure using the sensitivity information for the frame structure is applied. The fatigue life calculation for the frame structure is performed from the quasi-static and transient analysis and the characteristics of two methods are compared for the fatigue analysis. Then the reinforcement technique is applied. First, some design variables related to the locations of fatigue failure is selected. Then sensitivities of fatigue life at fracture points with respect to the variation of design variables are calculated and the vector composed of gaps between the target life and initial life cycles is calculated. If the number of fatigue fracture points is same as the number of design variables, the variations of the design variables are calculated from the linear algebraic equation. If not, the variations of the design variables are calculated from the optimization formulation with the constraints.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.319.2-319
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• 2002

The main obstacle to high track density in HDD id the structural resonances of the suspension. The most critical mode is sway mode and second torsion mode, when a data is read and written. It is common fact that the effect of two modes is smaller when a thickness is bulky. But the stiffness of suspension is smaller, the slider can follow a disk better. Because these two fact are reciprocal, a compromise is needed. So we investigated another method to improve band width without changing of the thickness of suspension but with changing of the shape. (omitted)

• 한국소음진동공학회논문집
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• 제25권11호
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• pp.731-738
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• 2015

This study proposed the method of the multi-crack detection using the sensitivity coefficient matrix which is calculated from the change of eigenvalues and eigenvectors before and after the crack. Each crack is modeled by a rotational springs. The method is applied to the cantilever beam with miulti-crack. The eigenvalues and eigenvectors are determined for different crack locations and depths. The prediction of multi-crack detection are in good agreement with the results of structural reanalysis.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.89-93
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• 1997

A superlastic material, aluminum - lithium alloy 8090, were examined with uniaxial tensile test to investigate its thermomechanical behavior. The tests were carried out at the strain-rates ranging from 2${\times}$10-4 to 1${\times}$10-2 and at the temperatures from 48 0$^{\circ}C$ to 540$^{\circ}C$. The experiments produced force-displacement curves which converted to stress-strain curves. From the curves, several important superplastic factor such as strain-rate sensitivity, optimum strain-rate and strength coefficient were obtained.

• 마이크로전자및패키징학회지
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• 제21권3호
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• pp.19-24
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• 2014

This article reviews the recent progress in nanowell array biosensors that use the label-free detection protocol, and are detected in their natural forms. These nanowell array biosensors are fabricated by nanofabrication technologies that should be useful for developing highly sensitive and selective also reproducible biosensors. Moreover, electrochemical method was selected as analysis method that has high sensitivity compared with other analysis. Finally, highly sensitive nanobiosensor was achieved by combining nanofabrication technologies and classical electrochemical method. Many examples are mentioned about the sensing performance of nanowell array biosensors will be evaluated in terms of sensitivity and detection limit compared with other micro-sized electrode without nanowell array.