• Title/Summary/Keyword: Experimental designs

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A Taguchi Approach to Parameter Setting in a Genetic Algorithm for General Job Shop Scheduling Problem

  • Sun, Ji Ung
    • Industrial Engineering and Management Systems
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    • v.6 no.2
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    • pp.119-124
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    • 2007
  • The most difficult and time-intensive issue in the successful implementation of genetic algorithms is to find good parameter setting, one of the most popular subjects of current research in genetic algorithms. In this study, we present a new efficient experimental design method for parameter optimization in a genetic algorithm for general job shop scheduling problem using the Taguchi method. Four genetic parameters including the population size, the crossover rate, the mutation rate, and the stopping condition are treated as design factors. For the performance characteristic, makespan is adopted. The number of jobs, the number of operations required to be processed in each job, and the number of machines are considered as noise factors in generating various job shop environments. A robust design experiment with inner and outer orthogonal arrays is conducted by computer simulation, and the optimal parameter setting is presented which consists of a combination of the level of each design factor. The validity of the optimal parameter setting is investigated by comparing its SN ratios with those obtained by an experiment with full factorial designs.

Supplementary analyses of economic X over bar chart model

  • Jeon, Tae-Bo
    • Korean Management Science Review
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    • v.12 no.1
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    • pp.111-124
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    • 1995
  • With the increasing interest of reducing process variation, statistical process control has served the pivotal tool in most industrial quality programs. In this study, system analyses have been performed associated with a cost incorporated version of a process control, a quadratic loss-based X over bar control chart model. Specifically, two issues, the capital/research investments for improvement of a system and the precision of a parameter estimation, have been addressed and discussed. Through the analysis of experimental results, we show that process variability is seen to be one of the most important sources of loss and quality improvement efforts should be directed to reduce this variability. We further derive the results that, even if the optimal designs may be sensitive, the model appears to be robust with regard to misspecification of parameters. The approach and discussion taken in this study provide a meaningful guide for proper process control. We conclude this study with providing general comments.

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Sensitivity of the $217Plus^{TM}$ System Model to Failure Causes (고장요인들에 대한 $217Plus^{TM}$ 시스템 모형의 민감도)

  • Jeon, Tae-Bo
    • Journal of Applied Reliability
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    • v.11 no.4
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    • pp.387-398
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    • 2011
  • $217Plus^{TM}$, a newly developed as a surrogate of the MIL-HDBK-217, may be widely applied for reliability predictions of electronic systems. In this study, we performed sensitivity study of the $217Plus^{TM}$ system model to various parameters. Specific attention was put to logistics model and its behavior has been examined in terms of non-component failure causes. We first briefly explained the $217Plus^{TM}$ methodology with system level failure rate evaluation. We then applied experimental designs with several failure causes as factors. We used an orthogonal array with three levels of each parameter. Our results indicate that cannot duplicate, induced, and wear-out causes have dominant effects on the system failures and design, parts, and system management have much less but a little strong effects. The results in this study not only figure out the behavior of the predicted failure rate as functions of failure causes but provide meaningful guidelines for practical applications.

Characteristics of a High Power Factor Boost Converter with Continuous Current Mode Control

  • Kim, Cherl-Jin;Jang, Jun-Young
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.4B no.2
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    • pp.65-72
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    • 2004
  • Switching power supply systems are widely used in many industrial fields. Power factor correction (PFC) circuits have a tendency to be applied in new power supply designs. The input active power factor correction (APFC) circuits can be implemented in either the two-stage approach or the single-stage approach. The two-stage approach can be classified into boost type PFC circuit and dc/dc converter. The power factor correction circuit with a boost converter used as an input power source is studied in this paper. In a boost power factor correction circuit there are two feedback control loops, which are a current feedback loop and a voltage feedback loop. In this paper, the regulation performance of output voltage and compensator to improve the transient response presented at the continuous conduction mode (CCM) of the boost PFC circuit is analyzed. The validity of designed boost PFC circuit is confirmed by MATLAB simulation and experimental results.

Characteristics Analysis of AFPM motor for low speed and high torque (저속-고토크용 AFPM 전동기의 특성해석)

  • Seo, Young-Taek;Kim, Chul-Ho;Kim, Hyoung-Gil;Oh, Chul-Soo
    • Proceedings of the KIEE Conference
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    • 2001.07b
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    • pp.641-643
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    • 2001
  • This paper presents the analysis, design and performance of an axial-flux permanent magnet(AFPM) motor with a core-less stator. Axial-flux permanent magnet motors prove to be the best candidate for application in electric vehicles(EVs) as direct drive wheel motors, as in comparison with conventional motors. They allow designs with higher compactness lightness and efficiency. The paper discusses design and construction of a prototype motor, and reports experimental results achieved from laboratory tests.

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An experimental study of Incompressible time based mass flow controller (비압축성 시간식 질량유량계의 특성에 관한 연구)

  • Chang, Young-Chul
    • Journal of the Semiconductor & Display Technology
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    • v.7 no.3
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    • pp.55-58
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    • 2008
  • The objective of this research is to design, manufacture and test a mass flow controller capable of measuring compressible as well as incompressible fluid flows based on a 'bucket and stop-watch' method. The basic principle behind such a system is the measurement of time, where the time taken to fill and empty a bucket of known volume is measured. This device should be able to handle fluid flows in the range of 0.1 ml/min to 10 ml/min within an accuracy of ${\pm}$1%. For the flow meter to be able to compete with established designs, it must be not only comparable in cost and robustness, but also very accurate and reliable as well.

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Steel nitriding optimization through multi-objective and FEM analysis

  • Cavaliere, Pasquale;Perrone, Angelo;Silvello, Alessio
    • Journal of Computational Design and Engineering
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    • v.3 no.1
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    • pp.71-90
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    • 2016
  • Steel nitriding is a thermo-chemical process leading to surface hardening and improvement in fatigue properties. The process is strongly influenced by many different variables such as steel composition, nitrogen potential, temperature, time, and quenching media. In the present study, the influence of such parameters affecting physic-chemical and mechanical properties of nitride steels was evaluated. The aim was to streamline the process by numerical-experimental analysis allowing defining the optimal conditions for the success of the process. Input parameters-output results correlations were calculated through the employment of a multi-objective optimization software, modeFRONTIER (Esteco). The mechanical and microstructural results belonging to the nitriding process, performed with different processing conditions for various steels, are presented. The data were employed to obtain the analytical equations describing nitriding behavior as a function of nitriding parameters and steel composition. The obtained model was validated, through control designs, and optimized by taking into account physical and processing conditions.

Structural Characteristics of Damaged Offshore Tubular Members

  • Cho, Sang-Rai;Kwon, Jong-Sig;Kwak, Dong-Il
    • Journal of Ocean Engineering and Technology
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    • v.24 no.4
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    • pp.1-7
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    • 2010
  • Over the past few decades various experimental and theoretical investigations have been performed on offshore tubular members with regard to damage resistance and residual strength. Analysis of damaged tubular members requires a three-dimensional shell analysis for accurate results. Even though various commercial packages are available for this purpose, a beam-column analysis is preferred for offshore structural designs. In this paper, empirical equations are provided for a more accurate beam-column analysis of damaged tubes including the relationships between the lateral denting load and the depth of the dent, the rate of dent deepening due to increasing curvature and the longitudinal variation in the dent depth of damaged tubes. A design equation to predict the ultimate bending capacities of damaged offshore tubular members is also presented.

A Study of Performance Analysis for a Double-Suction Centrifugal Pump (양쪽 흡입 원심펌프의 성능해석에 대한 연구)

  • Chung, Kyung-Nam;Park, Pyun-Goo;Cho, Hyun-Jun;Lee, Sang-Gu
    • The KSFM Journal of Fluid Machinery
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    • v.4 no.4 s.13
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    • pp.7-15
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    • 2001
  • Flow analysis was carried out for a double-suction centrifugal pump. Impeller-only models and a full pump model were used to simulate the velocity field and the pressure field of the pump. Heads and efficiencies were calculated with flow rates in order to obtain general performance of the pump. The calculation results were compared to the experimental data, and satisfactory results were obtained. Thus, it may be said that the CFD serves as a useful tool for pump designs.

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Design Program of impellers of Vacuum Cleaner (진공청소기 임펠러 설계 프로그램)

  • Ahn, K.-W.;Lee, S.;Baek, S.-J.;Kim, C.-J.;Jeon, W.-H.
    • 유체기계공업학회:학술대회논문집
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    • 2001.11a
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    • pp.54-60
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    • 2001
  • In this research, we developed a computer code that designs a compressor impeller, which serves as an essential component of a vacuum cleaner, and predicted its performance. The TEIS model originally developed by Japikse(1985), and the mean line analysis m combined to design the centrifugal impeller optimally. In this program the inlet geometry is designed by using the mean line analysis, and with assumption of resonable exit blade angle, the optimal geometry is searched by means of TEIS model and iterative scheme. The performance of designed impeller was compared with experimental data, and the far-field noise by the rotating impeller is also predicted.

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