• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.6
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• pp.70-76
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• 2011

This paper presents an optimization procedure for reducing warpage of injection molded part by using a volumetric shrinkage deviation as an objective function. A design of experiments based on orthogonal arrays was used in the optimization procedure, and the entire optimization was performed through a two stage process - a preliminary experimentation and a principal experimentation. Proposed optimization method was applied to the design of a CPU-base part in computer. With the moderate number of experiments, an optimal molding condition for uniform distribution of volumetric shrinkage was obtained, as a result, the warpage of the molded part was significantly reduced.

• Communications of the Korean Mathematical Society
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• v.15 no.2
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• pp.285-308
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• 2000

We generalize bi-orthogonal (non-orthogona) MRA to frame MRA in which the family of integer translates of a scaling func-tion forms a frame for the initial ladder space V0. We investigate the internal structure of frame MRA and establish the existence of a dual scaling function, and show that, unlike bi-orthogonal MRA, there ex-ists a frame MRA that has no (frame) 'wavelet'. Then we prove the existence of a dual wavelet under the assumption of the existence of a wavelet and present easy sufficient conditions for the existence of a wavelet. Finally we give a new proof of an equivalent condition for the translates of a function in L2(R) to be a frame of its closed linear span.

• Composites Research
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• v.29 no.5
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• pp.236-242
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• 2016

In this work, tensile and in-plane shear tests for thermoplastic glass fiber/polypropylene composites were performed at a thermo-forming temperature and their properties were characterized and mathematically expressed by using the non-orthogonal constitutive model. As for the thermo-forming test, half-dome experiments were carried out by varying the usage of a releasing agent and the weight of holders. As results, the optimum final shape having well-aligned symmetry and no wrinkle formation was obtained when the releasing agent was used, and it was found that the careful control of a holding force is crucial to manufacture the healthy product. Furthermore, FEM simulations based on the non-orthogonal model showed similar final shapes and tendency of wrinkle formation with experimental results, and confirmed that wrinkles increase with less holding force and higher punch force is required under high frictional condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.72-82
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• 2005

The objective of this paper is to describe the optimization of design parameters in a large-sized commercial bus heater system by using CFD(computational fluid dynamics) analysis and Taguchi method. In order to obtain the best combination of each control factor which results in a desired performance of heater system, the parameter design of the Taguchi method is adopted for the robust design considering the dynamic characteristic. The research activity may be divided into four phases. The first one is analyzing the problem, i.e., ascertaining the influential factors. In the second phase the levels were set in such a way that their variation would significantly influence the response. In the third phase the experimental runs were designed. In the final phase the planned runs were carried out numerically to evaluate the optimal combination of factors which is able to provide the best response. In this study, eight factors were considered for the analysis: one with two level and seven with three level combinations comprising the $L_{18}(2^1{\times}3^7)$ orthogonal array. The results of this study can be summarized as follows ; (i)The optimum condition of control factor is a set of <$A_2\;B_1\;C_3\;D_3\;E_1\;F_2\;G_3\;H_2$> where A is shape of the outer fin, B is pitch of the outer fin, C is height of the outer fin, D is the inner fin number, E is the inner fin height, F is length of the flame guide, G is diameter of the heating element and H is clearance between air guide and heating element. (ii)The heat capacity of heated discharge air under the optimum condition satisfies the equation y=0.6M w here M is a signal factor. (iii)The warm-up rate improves about three times, more largely as com pared with the current condition, which results in about 9.2minutes reduction.

• Journal of Korean Society for Quality Management
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• v.7 no.2
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• pp.22-28
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• 1979

The problem considered in this paper is to select the vital factor effect to the product quality through the experimental design and analysis of response surface, so as to control the quality improvement of industrial product. In this time, even through the mathematical model is unknown it could be applicable to control the quality of industrial products and to determine optimum operating condition for many technical fields, particulary, for industrial manufacturing process. When a set of data is available from an experimental design, it is often of interest 1:0 fit polynominal repression model in independent variables (eg, time, temperature, pressure, etc) the optimize the response variable (eg. yield, strength etc). This paper proposes a method known to obtain the optimum operating condition, and how to find the condition by using table of orthogonal array experiments, and optimization methodology of statistical model. A criterion can be applied determining to optimum operating conditions in manufacturing industry and improving the fit of response surface which may be used for prediction of responses and quality control of industrial products.

• Communications for Statistical Applications and Methods
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• v.30 no.6
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• pp.631-652
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• 2023

In the two-condition within-subject mediation design, pairs of variables such as mediator and outcome are observed under two treatment conditions. The main objective of the design is to investigate the indirect effects of the condition difference (sum) on the outcome difference (sum) through the mediator difference (sum) for comparison of two treatment conditions. The natural condition variables mean the original variables, while the rotated condition variables mean the difference and the sum of two natural variables. The outcome difference (sum) is expressed as a linear model regressed on two natural (rotated) mediators as a parallel two-mediator design in two condition approaches: the natural condition approach uses regressors as the natural condition variables, while the rotated condition approach uses regressors as the rotated condition variables. In each condition approach, the total indirect effect on the outcome difference (sum) can be expressed as the sum of two individual indirect effects: within- and cross-condition indirect effects. The total indirect effects on the outcome difference (sum) for both condition approaches are the same. The invariance of the total indirect effect makes it possible to analyze the nature of two pairs of individual indirect effects induced from the natural conditions and the rotated conditions. The two-condition within-subject design is extended to the addition of a between-subject moderator. Probing of the conditional indirect effects given the moderator values is implemented by plotting the bootstrap confidence intervals of indirect effects against the moderator values. The expected indirect effect with respect to the moderator is derived to provide the overall effect of moderator on the indirect effect. The model coefficients are estimated by the structural equation modeling approach and their statistical significance is tested using the bias-corrected bootstrap confidence intervals. All procedures are evaluated using function lavaan() of package {lavaan} in R.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.32-37
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• 2014

In this study, the optimum design process of an indoor package air-conditioner (PAC) was implemented by Taguchi method. The goal of this study is to obtain the best set condition of each control factor composing of an indoor PAC. The number of revolution of a double inlet sirocco fan installed in an indoor PAC was measured by the orthogonal array of $L_{18}(2^3{\times}3^4)$ and analysed by using the-smaller- the-better characteristic among the static characteristic analyses. As a result, the optimum condition of an indoor PAC was found as a set of when the cost of production, assembling and working conditions were considered. Moreover, the number of revolution of a double-inlet sirocco fan used for an optimum condition was reduced about 8.5% more than that of a standard condition for the target flowrate of $18.5m^3/min$.

• Journal of the Korean Statistical Society
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• v.21 no.1
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• pp.80-86
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• 1992

The concept of Balanced Factorial Experiment (BFE) was introduced by Shah (1958). The conditions for BFE were set up by Kurkjian and Zelen (1963) and Kshirsagar (1966). Generalized Cyclic Factorial Experiment (GCFE), which is more wide class of designs than BFE, do not satisfy the condition of BFE. So all contrasts belonging to the same interaction are not estimated with equal variance. The main purpose of this paper is to show that GCFE have orthogonal factorial structure and the scheme of the size of variances for all normalized contrasts in GCFE is similar to the original intra-block association scheme.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.1 no.1
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• pp.1-34
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• 1997

In this study, various available meshless methods are briefly reviewed and the connection among them is investigated. The objective of meshless methods is to eliminate some difficulties which are originated from reliance on a mesh by constructing the approximation entirely in terms of nodes. Especially, focusing on Element Free Galerkin Method(EFGM) based on moving least square interpolants(MLSI), a new implementation is developed based on a variational principle with penalty function method were used to enforce the essential boundary condition. In addition, the weighted orthogonal basis functions are constructed to overcome disadvantage of MLSI.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.698-706
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• 2016

Orthogonal frequency division multiplexing (OFDM) has high peak to power ratio (PAPR). High PAPR makes problems such as signal distortion and circuit cost increasing. To solve the problemsm several PAPR reduction methods have been proposed. However, synchronization and orthogonality in OFDM systems may be a limitation to reduce latency for 5G networks. Generalized frequency division multiplexing (GFDM) is one of the possible solutions for asynchronous and non-orthogonal systems, which are more preferable to reduce the latency. However, multiple subsymbols in GFDM result in more superposition in time domain, GFDM has higher PAPR. Selective mapping (SLM) is one of PAPR reduction techniques in OFDM, which uses phase shift. The PAPR of GFDM SLM is compared to conventional GFDM and OFDM SLM in terms of PAPR reduction enhancement via numerical simulations. In addition, the out-of-band performance is analyzed in the aspect of asynchronous condition interference.