• Journal of the Korean Society for Precision Engineering
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• 제19권10호
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• pp.120-129
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• 2002

An integrated structure and controller design approach for rotating cantilever beam is presented. An optimization method is developed for improving positioning performance considering the elastic deformations during high speed rotation and adopting the beam shape and the control gains as design variables. For this end, a dynamic model is setup by the finite element method according to the shape of the beam. The mass and stiffness of the beam are distributed in such a way that the closed-loop poles of the control system should be located leftmost in the complex s-plane. For optimization method, the simulated annealing method is employed which has higher probability to find the global minimum than the gradient-based down-hill methods. Sequential design and simultaneous design methods are proposed to obtain the optimal shape and controller. Simulations are performed with new designs by the two methods to verify the effectiveness of the approach and the results show that the settling time is improved for point-to-point position controls.

• Journal of Korean Academy of Fundamentals of Nursing
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• 제20권4호
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• pp.400-409
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• 2013

Purpose: This study was conducted to define factors influencing health-related quality of life (HRQOL) in women undergraduates. Independent variables of physical activity, attitude to eating, satisfaction with body shape, stress and self-esteem were used to predict HRQOL. Method: Data were analyzed using the SPSS/WIN 20.0 program for descriptive statistics, Pearson correlation coefficients and stepwise multiple regression. Participants were 245 women undergraduates who were recruited from July to September 2012. Result: The mean for the physical component summary (PCS) of HRQOL was 73.89, and for the mental component summary (MCS) was 68.45. There were significant correlations between attitude to eating, satisfaction with body shape, stress, self-esteem and the two components of HRQOL. The groups with minimal or health enhancing activity were significantly higher in PCS and MCS than the inactivity group. Stepwise multiple regression analysis indicated that 35% of the variance in PCS was significantly accounted for by self-esteem, perceived stress, attitude to eating, and physical activity, and 45% of the variance in MCS was significantly accounted for by perceived stress, self-esteem, attitude to eating, and satisfaction with body shape. Conclusion: The results indicate that these factors influencing HRQOL should be considered when developing programs to improve HRQOL for women undergraduates.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제11권5호
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• pp.332-339
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• 1986

This paper proposes a new method for the normalization of shape pattern based on Gaussian probability density function to increase automatic recognition rate of hand-written Hangul pattern. The sizes of hand-written Hangul pattern are detected from the input images, and pattern sizes are normalized by two variables interpolation. The pattrn shapes are noralized by letting correlation coefficients equal to zero. It is analyzed theoretically and verified through computer simulation for the relation between input image and normaized shape pattern. It is confirmed that this method is effective and reasonable for deformed hand-written Hangul pattern. Experimental resu results show that the declination. size and stroke width of hand-written Hangul patterns are mych improved.

• Journal of Korea Foundry Society
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• 제36권1호
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• pp.10-17
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• 2016

Numerical analysis has been performed to evaluate effect of the shape variables such as core length, slot width and slot length on misrun in aluminum die casting process for motor rotor. The predictive method for misrun in diecasting process was established by comparing the result of numerical analysis and an actual motor rotor. Solidification modulus was introduced to predict quantitatively the castability of aluminum diecasting process for motor rotor. It was found that there are minimum critical solidification modulus and slot width to prevent misrun according to core length through diecasting limit diagram proposed using the predictive method. The critical solidification modulus and slot width increase as core length increases to prevent misrun of aluminum motor rotor in diecasting process. Based on the results, the design criteria of slot shape to prevent misrun of aluminum motor rotor with various core length were established.

• The KSFM Journal of Fluid Machinery
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• 제13권6호
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• pp.42-50
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• 2010

The present analysis deals with a numerical procedure for optimizing the shape of elliptical dimples in a cooling channel. The three-dimensional Reynolds-averaged Navier-Stokes (RANS) analysis is employed in conjunction with the SST model for predictions of the turbulent flow and the heat transfer. Three non-dimensional geometric design variables, such as the ellipse dimple diameter ratio, ratio of the dimple depth to the average diameter, and ratio of the distance between dimples to the pitch are considered in the optimization. Twenty-one experimental points within design space are selected by Latin Hypercube Sampling. Each objective function values at these points are evaluated by RANS analysis and producing optimal point using surrogate model. The linear combination of heat transfer coefficient and friction loss related terms with a weighting factor is defined as the objective function. The results show that the optimized elliptical dimple shape improves considerably the heat transfer performance than the circular dimple shape.

• Transactions of Materials Processing
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• 제29권5호
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• pp.282-289
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• 2020

Flexible roll forming is an advanced sheet-metal-forming process that allows the production of parts with various cross-sections. During the flexible process, material is subjected to three-dimensional deformation such as transverse bending, inhomogeneous elongations, or contraction. Because of the effects of process variables on the quality of the roll-formed products, the approaches used to investigate the roll-forming process have been largely dependent on experience and trial- and-error methods. Web-warping is one of the major shape defects encountered in flexible roll forming. In this study, an SVR model was developed to predict the web-warping during the flexible roll forming process. In the development of the SVR model, three process parameters, namely the forming-roll speed condition, leveling-roll height, and bend angle were considered as the model inputs, and the web-warping height was used as the response variable for three blank shapes; rectangular, concave, and convex shape. MATLAB software was used to train the SVR model and optimize three hyperparameters (λ, ε, and γ). To evaluate the SVR model performance, the statistical analysis was carried out based on the three indicators: the root-mean-square error, mean absolute error, and relative root-mean-square error.

• Journal of the Korea institute for structural maintenance and inspection
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• 제9권3호
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• pp.93-100
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• 2005

The purpose of this study is to investigate the physical properties of porous concrete according to the aggregate shape and size which is produced by con crusher and impact crusher. For this purpose, the selected test variables were the aggregate size and shape, the ratio of water to cement and the ratio of paste to aggregate. The results of this study showed that its economic performance and physical properties were improved using the aggregate made by impact crusher. The coefficient of permeability and compressive strength of porous concrete had a close correlationship with the void ratio, and it was suggested as a function of void ratio.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제29권4호
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• pp.460-468
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• 2005

Analyses of flow and heat transfer characteristics and shape optimization of internally finned circular tubes have been performed for three-dimensional periodically fully developed turbulent flow and heat transfer. CFD and mathematical optimization are coupled in order to optimize the shape of heat exchanger. The design variables such as fin widths $(d_{1},\;d_{2})$ and fin height (h) are numerically optimized by minimizing the pressure loss and maximizing the heat transfer rate for limiting conditions of $d_{1}=0.2\~1.5\;mm,\;d_{2}=0.2\~1.5\;mm,$ and $h=0.2\~1.5mm$. Due to the periodic boundary conditions along main flow direction, the three layers of meshes are considered. The flow and thermal fields are predicted using the finite volume method and the optimization is carried out by means of the sequential quadratic programming (SQP) method which is widely used in the constrained nonlinear optimization problem.

• Journal of the Architectural Institute of Korea Structure & Construction
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• 제34권11호
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• pp.3-10
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• 2018

Cladding that finishes the exterior of a building could enhance the value of the building, and shape control is an important factor. With the recent development of 3D printing, cementitious claddings were printed by 3D printer in China, U.S.A and elsewhere. On the other hand, the structural safety of the exterior panel should be examined, as casualties occur when the exterior panel fails due to typhoon or impact. Cement-based cladding is reinforced by wire mesh to improve safety. Introducing 3D printing composite system with polymer and cement, makes it possible to produce claddings fast and accurate. Prior to the development of 3D printing cementitious cladding, the major parameters influencing the optimal shape were identified based on structural performance. The wind load, joint, and bond behavior between polymer and cement were considered. Polymer laminate shape, order, and thickness were variables, and finite element analysis was performed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제20권12호
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• pp.36-43
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• 2021

In this study, the optimal feed system and process conditions that can simultaneously minimize each warpage occurring in the two shape features of the 2P Header HSG, a connector part for automobiles, were determined through injection molding simulation analysis. First, we defined each warping deformation of the two features geometrically and quantified them approximately using the injection molding simulation data. For design optimization, a full factorial experiment was conducted considering the feed system, resin temperature, and packing pressure as design variables, and a follow-up experiment was conducted based on the analysis of the average warpage. In this study, an optimal design was generated considering both the warpage result and resin-saving effect. In the optimal design, the warpages of the two shape features were predicted to be 0.18 and 0.29 mm, and these warpages were found to meet the allowable limit of warpage, which is 0.3 mm, for part assembly.