• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.225-232
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• 1999

The effect of manufacturing parameters such as molding and curing conditions on friction characteristics of friction materials was studied using a pad-on-disk type friction tester. Friction materials containing 15 ingredients were investigated for an optimal manufacturing condition for the best friction characteristics employing Taguchi robust experimental design. The main effects were different for mechanical properties and friction characteristics and were strongly influenced by manufacturing conditions. An optimum manufacturing condition was obtained to achieve the best friction characteristics concerning mechanical properties(hardness, porosity, wear resistance), friction stability, and change of rotor temperature.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.3
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• pp.459-471
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• 1996

This paper considers ramp tests for exponential lifetime distribution when there are limitations on test stress and test time. The inverse power law and a cumulative exposure model are assumed. Maximum likelihood (ML) estimators of model parameters and their asymptotic covariance matrix are obtained. The optimum ramp test plans are also found which minimize the asymptotic variance of the ML estimator of the log mean life at design constant stress. For selected values of the design parameters, tables useful for finding optimal test plans are given. The effect of the pre-estimates of design parameters is studied.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.199-205
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• 2016

A thin sheet of metal with corrugated structures has been utilized in various devices: heat exchangers, separators in fuel cells, and many others. However, it is not easy to fabricate thin corrugated structures using a single-step stamping process due to their geometrical complexity. To solve this problem, firstly, a plate type heat exchanger was redesigned to attain the optimal value of aspect ratio and the optimal shape of corrugated structures for the actual loading conditions. A forming analysis of the corrugated plate was then carried out to determine the process parameters. From this work, the optimal value of aspect ratio was found to be 4.6. In addition, the process parameters of heat exchanger forming were optimized using the optimal value of aspect ratio, and the analytical results were evaluated through experiments. The results obtained indicated good agreements between them.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.41
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• pp.15-23
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• 1997

Because of various request of consummer and rapidly chang, a product change and new-production come out variously. To satisfy the condition, companies must develop the product of rapidity and good quality. But, a product design difficults to consider many parameters and increase the level of each parameter. In order to solve this problem, this paper studies out algorithms taken into account more parameters and increased the level of parameters using the Genetic Algorithms. Because this algorithm can search detailed and wide for the level of parameter, in case of new-product development, we can use it for designing parameters of new-product.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.298-303
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• 2004

parameters in surface grinding. Taguchi method which is one of the design of experiments has been introduced in achieving the aims. The process parameters were the grain size, the wheel speed, the depth of cut and the table speed. The effect of the process parameters on the geometric error was examined and an optimal set of the parameters was selected to minimize the geometric error within the controllable range of the used grinding machine. The reliability of the results was evaluated by the ANOVA.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.1994-2003
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• 2003

The vibration of a flexible cantilever tube with nonlinear constraints when it is subjected to flow internally with fluids is examined by experimental and theoretical analysis. These kinds of studies have been performed to find the existence of chaotic motion. In this paper, the important parameters of the system leading to such a chaotic motion such as Young's modulus and the coefficient of viscoelastic damping are discussed. The parameters are investigated by means of system identification so that comparisons are made between numerical analysis using the design parameters and the experimental results. The chaotic region led by several period-doubling bifurcations beyond the Hopf bifurcation is also re-established with phase portraits, bifurcation diagram and Lyapunov exponent so that one can define optimal parameters for system design.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.13-19
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• 2004

This paper deals with the analysis of geometric error and the optimization of process parameters in surface grinding. Taguchi method which is one of the design of experiments has been introduced in achieving the aims. The process parameters were the grain size, the wheel speed, the depth of cut and the table speed. The effect of the process parameters on the geometric error was examined and an optimal set of the parameters was selected to minimize the geometric error within the controllable range of the used grinding machine. The reliability of the results was evaluated by the ANOVA.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.242-248
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• 2000

This paper has focused on the optimization of the cutting parameters for turning operation based on the Taguchi method. Four cutting parameters, namely, cutting speed, feed, depth of cut and nose radius are optimized with consideration of the surface roughness. The design and analysis of experiments are conducted to study the performance characteristic. The effects of these parameters on the surface roughness have been investigated using the signal-to-noise (S/N) ratio, analysis of variance (ANOVA). The experiments have been peformed using coated tungsten carbide inserts without any cutting fluid. Experimental results illustrate the effectiveness of this approach.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.3
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• pp.367-379
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• 1998

This paper considers two modes of partially accelerated life tests for items having Weibull lifetime distributions. In a use-to-acclerated mode each item is first run at use condition and, if it does not fail for a specified time, then it is run at accelerated condition until a predetermined censoring time. In an accelerated-to-use mode each one is first run at accelerated condition and, if it does not fail for a specified time, then it is run at use condition. Maximum likelihood estimators of the parameters of the lifetime distribution at use condition, and the 'acceleration factor' are obtained. The stress change time for each mode is determined to minimize the asymptotic variance of the acceleration factor, and the two modes are compared. For selected values of the design parameters the optimum plans are obtained, and the effects of the incorrect pre-estimates of the design parameters are investigated. Minimizing the generalized asymptotic variance of the estimators of the model parameters is also considered as an optimality criterion.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.729-733
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• 2003

Hybrid RMU is a kind of power circuit breaker and protects electric devices from over-current. In this paper we built a dynamic model of RMU driving mechanism using ADAMS and performed a optimal design of several design parameters. Finally we developed a prototype of RMU driving mechanism through results of analysis and confirmed it to satisfy design requisitions.