• Journal of Ocean Engineering and Technology
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• v.11 no.1
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• pp.3-9
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• 1997

In this paper, design sensivity of plate natural frequency is computed for thickness design variables. Once the variational equation is derived from Lagrange quation using the virtual displacement, governing energy bilinear form is obtained and sensivity equation is formulated through the first variation. Natural frequency is obtained using the commercial FEM code and the accuracy of sensivity is verified by finite difference. The accuracy of natural frequency and sensivity improves for the fine mesh model.

• Journal of Power Electronics
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• v.7 no.1
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• pp.13-20
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• 2007

LLC resonant converters display many advantages over the conventional LC series resonant converter such as narrow frequency variation over wide range of load and input variation and zero voltage switching even under no load conditions. This paper presents analysis and design consideration for the half bridge LLC resonant converter. Using the fundamental approximation, the gain equation is obtained, where the leakage inductance in the transformer secondary side is also considered. Based on the gain equation, the practical design procedure is investigated to optimize the resonant network for a given input/output specifications. The design procedure is verified through an experimental prototype of the 115W half-bridge LLC resonant converter.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.951-953
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• 1993

This study presents a design methods for linear DC motor and the designed motor is analyzed. To design the linear DC motor, magnetic circuit design is introduced and characteristics of LDM is analyzed by using the voltage equation aid dynamic equation. And the thrust characteristics are investigated using MEXWELL 2D.

• Journal of the Korean Statistical Society
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• v.20 no.2
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• pp.147-155
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• 1991

This paper treats a robust design criterion which minimizes the effects of outliers and model inadequacy, and investigates robust designs for some response surface designs. In order to develop a robust design criterion and robust design, the integrated mean squared error of *(equation omitted) over a region is utilized, where *(equation omitted). is the estimated response by the minimum bias estimation proposed by carson, Manson and Hader (1969) . According to the number of aberrant observations and their positions, the proposed criterion and designs are studied. Also further development of the proposed criterion is treated when outliers can occur in any position of a design.

• Journal of Korea Water Resources Association
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• v.51 no.3
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• pp.263-272
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• 2018

For the design of hydraulic structures, the design flood discharge corresponding to a specific frequency is generally used by using the design storm calculated according to the rainfall-runoff relationship. In the past, empirical equations such as rational equations were used to calculate the peak flow rate. However, as the duration of rainfall is prolonged, the outflow patterns are different from the actual events, so the accuracy of the temporal distribution of the probability rainfall becomes important. In the present work, Huff's quartile method is used for the temporal distribution of rainfall, and the third quartile is generally used. The regression equation for Huff's quadratic curve applies a sixth order polynomial equation because of its high accuracy throughout the duration of rainfall. However, in statistical modeling, the regression equation needs to be concise in accordance with the principle of simplicity, and it is necessary to determine the regression coefficient based on the statistical significance level. Therefore, in this study, the statistical significance test for regression equation for temporal distribution of the Huff's quartile method, which is used as the temporal distribution method of design rainfall, is conducted for 69 rainfall observation stations under the jurisdiction of the Korea Meteorological Administration. It is statistically significant that the regression equation of the Huff's quartile method can be considered only up to the 4th order polynomial equation, as the regression coefficient is significant in most of the 69 rainfall observation stations.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.188-191
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• 1996

In this paper, we derive dynamic equation of double pole inverted pendulum using Lagrangian equation, and design the fuzzy sliding mode controller. We demonstrate that the designed controller regulates double pole simultaneously regardless of cart position by computer simulation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2172-2180
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• 1993

Under general loadings, including body forces, crack-face tractions and thermal loading, the energy release rate equation for a two-dimensional cracked body is presented. Defining the virtual crack extension as the variation of the geometry, the equation is directly derived by a shape design sensitivity of the potential energy. Although the form of the derived energy release rate equation is different from other researchers's results, the three example show that the former is exactly the same as the latter. However, the final integral equation do not involve the derivative of the displacement on the crack surface and crack tip region, thereby improving the numerical accuracy in the computation of the energy relase rate. Moreover, as it was derived from the governing equation including non-linear elasticity without special assumptions, the energy release rate of a elasto-plastic fracture can be obtained and any numerical stress analysis method can be applied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.9 s.240
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• pp.1270-1275
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• 2005

Rolling process to fabricate a strip with even thickness is significant to enhance the quality of the strip. The thickness of a strip can be effectively controlled by pair-cross mills. However, pair-cross mill generates thrust in the axial direction of roller and causes skewness, deflection, twist and even accidental roll chock failure. Therefore, accurate estimation of the thrust of the pair-cross mill during rolling process is necessary to monitor the failure of roll and the quality of products. An empirical equation given by Mitsubishi Heavy Industry (MHI) is hitherto employed, where the thrust is expressed in terms of rolling force, reduction ratio and crossed angle. However it turns out that the MHI empirical equation provides somehow inaccurate and unsuitable thrust in practical rolling processes. Moreover, we learn that three parameters involved in MHI equation are coupled each other. In this paper, axiomatic design principle is employed to select appropriate parameters involved in approximate equation in order to make parameters uncoupled. A quadratic equation using response surface method with new parameters is suggested. The accuracy of the approximate model is examined by comparing with real experimental data.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.1
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• pp.48-58
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• 2002

There is a purpose of this study for the proposal of the optimum technique utilized for the vibration design initial step. The stiffened plate structure for the ship hull is made for analysis model. To begin with, dynamic characteristics of stiffened plate structure is analysed using FEM. Main vibrational mode of the structure is decided in the analytical result of FEM. The simplified equation on the natural frequency of the main vibrational mode is induced. Next, sensitivity analysis is carried out using the simplified equation, and rate of change of dynamic characteristics is calculated. Then, amount of design variable is calculated using this sensitivity value and optimum structural modification method. The change of natural frequency is made to be an objective function. Thickness of panel, cross section moment of stiffener and girder become a design variable. The validity of the optimization method using simplified equation is examined. It is shown that the result effective in the optimum modification for natural frequency of the stiffened plate structure.

• Journal of Mechanical Science and Technology
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• v.16 no.8
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• pp.1102-1108
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• 2002

In this study, a topological design sensitivity of the ai. bearing surface (ABS) is suggested by using an adjoint variable method. The discrete form of the generalized lubrication equation based on a control volume formulation is used as a compatible condition. A residual function of the slider is considered as an equality constraint function, which represents the slider in equilibrium. The slider thickness parameters at all grid cells are chosen as design variables since they are the topological parameters determining the ABS shape. Then, a complicated adjoint variable equation is formulated to directly handle the highly nonlinear and asymmetric coefficient matrix and vector in the discrete system equation of air-lubricated slider bearings. An alternating direction implicit (ADI) scheme is utilized for the numerical calculation. This is an efficient iterative solver to solve large-scale problem in special band storage. Then, a computer program is developed and applied to a slider model of a sophisticated shape. The simulation results of design sensitivity analysis (DSA) are directly compared with those of FDM at the randomly selected grid cells to show the effectiveness of the proposed approach. The overall distribution of DSA results are reported, clearly showing the region on the ABS where special attention should be given during the manufacturing process.