• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.351-358
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• 2005

Many methods have been developed and are in use for structural size optimization problems, In which the cross-sectional areas or sizing variables are usually assumed to be continuous. In most practical structural engineering design problems, however, the design variables are discrete. This paper proposes an efficient optimization method for structures with discrete-sized variables based on the harmony search (HS) meta-heuristic algorithm. The recently developed HS algorithm was conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary In this paper, a discrete search strategy using the HS algorithm is presented in detail and its effectiveness and robustness, as compared to current discrete optimization methods, are demonstrated through a standard truss example. The numerical results reveal that the proposed method is a powerful search and design optimization tool for structures with discrete-sized members, and may yield better solutions than those obtained using current method.

• Journal of information and communication convergence engineering
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• v.12 no.4
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• pp.257-262
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• 2014

Meta-analysis is a statistical integration method that delivers an opportunity to overview the entire result by integrating and analyzing many quantitative research results. This study will find meaningful mediator variables for criterion variables that affect purchase and repurchase intentions in e-commerce, on the basis of the results of a meta-analysis. We reviewed a total of 114 e-commerce studies published in Korean journals between 2000 and 2014, where a cause and effect relationship is established between variables that are specified in the conceptual model of this study. In this meta-analysis, the path between trust and purchase intention showed the biggest effect size. The second biggest effect size was found in the path between commitment and purchase intention, while the smallest one was obtained with perceived. Thus, we present the theoretical and practical implications of these results and discuss the differences among these results through a comparative analysis with previous studies.

• Journal of Distribution Science
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• v.17 no.10
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• pp.17-26
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• 2019

Purpose - This research investigates the old marketing mix approach to satisfaction and loyalty from the perspective of research subjects of Samsung brand smartphone cases through empirical testing involving product quality, price, distribution channel variables as antecedent variables. Research design, data, and methodology - This study emphasizes the empirical/quantitative concept by using a survey as a data collection tool. The number of samples used was 179 eligible respondents who used Samsung smartphone devices for more than five years. Statistical testing tools use PLS with several testing stages such as the classical assumption test to the hypothesis testing stage. Results - The nine hypotheses proposed, as many as two hypotheses were proposed, namely intervening relationships involving Price and Distribution channel variables on customer satisfaction and customer loyalty. Conclusions - Product quality is the essential component affecting customer satisfaction and loyalty while distribution channel is a complementary component that is no less important to measure the extent to which customer satisfaction expectations and customer loyalty are realized for the product quality of the products that have been produced and marketed. The price component is not the only reason to make consumers satisfied and loyal.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.11a
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• pp.99-106
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• 2001

The design for cold extrusion dies is very important, because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, the used assumptions are such that the yield strength of each ring is selected according to the allowable tensile or compressive hoop stress in each ring and the maximum allowable inner pressure, when yielding occurs in one ring of the dies, is obtained by the proposed equation. In order to obtain design variables, such as diameter ratios and interferences, using the maximum inner pressure, the flexible tolerance method was used for shrink-fitted thick-walled cylinders. ANSYS APDL was used to perform the repeated analysis of deformation of the dies due to the variation of the design variables. The response surface methodology is utilized to analyze the relationship between the design variables and the maximum radial displacement of the die insert during extrusion. From the results, it is found that outer diameter of the die Insert has the largest effect on the minimization of maximum radial displacement at the inner surface of the dies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1574-1582
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• 2004

Binary manipulators have recently received much attention due to hyper-redundancy, light weight, good controllability and high reliability. The precise positioning of the manipulator end-effecter requires the use of many modules, which results in a high-dimensional workspace. When the workspace dimension is large, existing inverse kinematics methods such as the Ebert-Uphoff algorithm may require impractically large memory size in determining the binary positions of all actuators. To overcome this limitation, we propose a new inverse kinematics algorithm: the inverse kinematics problem is formulated as an optimization problem using real-valued design variables, The key procedure in this approach is to transform the integer-variable optimization problem to a real-variable optimization problem and to push the real-valued design variables as closely as possible to the permissible binary values. Since the actual optimization is performed in real-valued design variables, the design sensitivity becomes readily available, and the optimization method becomes extremely efficient. Because the proposed formulation is quite general, other design considerations such as operation power minimization can be easily considered.

• Journal of the Korean Data and Information Science Society
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• v.28 no.5
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• pp.971-980
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• 2017

The varying coefficient regression model has gained lots of attention since it is capable to model dynamic changes of regression coefficients in many regression problems of science. In this paper we propose a varying coefficient regression model that effectively considers the errors on both input and response variables, which utilizes the kernel method in estimating the varying coefficient which is the unknown nonlinear function of smoothing variables. We provide a generalized cross validation method for choosing the hyper-parameters which affect the performance of the proposed model. The proposed method is evaluated through numerical studies.

• Journal of Families and Better Life
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• v.32 no.1
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• pp.63-79
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• 2014

Recently, in our society, the use of smartphones has been widespread and changed our lives positively; however, the excessive use of smartphones has also produced many side effects. In particular, we can see that the reckless use of smartphones has constantly increased smartphone addiction propensities. University students, too, show smartphone addiction propensities more and more gradually; therefore this study intends to perform research related with smartphone addiction propensities with university students as the subjects. Since it is more and more important to perform leisure activities to prevent smartphone addiction and reduce addiction propensities, it can be said that the research on the correlation between leisure activities and smartphone addiction propensities is significant. The major findings of the research are as follows: First, among the smartphone addiction propensities, their tolerance and disturbance of adaptive function were relatively higher than other factors. Second, overall smartphone addiction affects the variables of gender (male), school year (freshmen), economic leisure constraints, time leisure constraints, and the adequacy of travel behavior, sports behavior, media use behavior, reading behavior, volunteer work and religious behavior. The adequacy of the media use behavior variables showed the greatest impact.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.506-509
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• 2006

Shaped Sound Focusing is defined as the generation of acoustically bright shape in space using multiple sources. The acoustically bright shape is a spatially focused region with relatively high acoustic potential energy level. In view of the energy transfer, acoustical focusing is essential because acoustic energy is very small to use other type of energy. Practically, focused sound shape control not a point is meaningful because there are so many needs to enlarge the focal region especially in clinical uses and others. If focused sound shape can be controlled, it offers various kinds of solutions for clinical uses and others because a regional focusing is essentially needed to reduce a treatment time and enhance the performance of transducers. For making the shaped-sound field, control variables, such as a number of sources, excitation frequency, source positioning, etc., should be taken according to geometrical sound shape. To verify these relations between them, wavenumber domain matching method is suggested because wavenumber spectrum can provide the information of control variables of sources. In this paper, the procedures of shaped sound focusing using wavenumber domain matching and relations between control variables and geometrical sound shape are covered in case of an acoustical ring.

• Journal of the Korean Institute of Rural Architecture
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• v.11 no.2
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• pp.29-36
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• 2009

The recently research shows that the many tourists of Suanbo hot spring waters haven't satisfied the service. These reasons due to that they did not properly consider the satisfaction of tourists' services and index. However, satisfaction level of hot spring waters tourists is interacted complicatedly with various factors, the interactions are not easily identified. A structural equations model is adopted to capture the complex relationships among variables. In the model estimation, we used 140 survey data of Suanbo hot spring waters tourists. The SEM with several factors mentioned above as exogenous variables shows that they have complex and strong relationships. As results of a SEM, it was shown that variables influencing in pleasance are surrounding scenery, clean condition inside hot springs and congestion for use in satisfaction level most. Secondly, in case of kindness, attitudes of employees influence in satisfaction level most, followed by attitudes of residents and kindness of employees. Thirdly, in case of information, it was shown guidance on internal roads influencing in satisfaction level most, followed by guidance on owner drivers, guidance on surrounding tourist attractions and guidance on public transportation. Finally, a variable influencing in accessibility most is satisfaction level of public transportation.

• The Korean Journal of Applied Statistics
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• v.8 no.1
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• pp.61-74
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• 1995

These days, many kinds of graphical methods have been developed, and it is possible to get information directly from data. Especially, R-code (Cook and Weisberg, 1994) make it possible to draw various kinds of two and three dimensional plots, and to rotate the axis of the plots. But the maximum dimensional of the plot is three, so we can not draw plot of one response variable with more than three explanatory variables. Li(1991, 1992) has developed a method to reduce the dimension of the explanatory variables, so it is possible to draw lower dimensional plots to get information of the full explanatory variables. One of the dimension reduction method developed by Li is pHd. In this paper, we have tried to apply the pHd method for the model with multivariate response.