• Journal of Korean Society for Quality Management
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• v.17 no.2
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• pp.121-141
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• 1989

This paper is concerned with a development and evaluation of heuristics for the multi-stage sequence dependent flowshop sequencing. Eighteen heuristics, CAM1, CAM2, and etc., are proposed. The performance measure is a makespan which is to be minimized. The experiment for each algorithm is designed for a 4*3*3 factorial design with 360 observations. The experimental factors are PS(ratio of processing times to setup times), M(number of machines), N(number of jobs). The makespan of the proposed heuristics is compared with the optimal makespan obtained by the complete enumeration of schedules. This yardstick of comparison is called a relative error. The mean relative errors of the eighteen heuristics are from 2.048% to 8.717%. The computational results are analysed using SPSS. The experimental results show that the three factors are statistically significant at 5% level. The simulation for the large size problems is conducted to show having the similar computational results like the small size problems.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.2
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• pp.81-91
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• 1995

A miniature size electrostatic induction motor has been fabricated and studied with emphasis on the role of the surface resistivity, the relative dielectric constant of the rotor surface materials and the rotor liner materials, which control the charge induction and relaxation on the rotor surface and the field intensity between the rotor and the stator. It is found that the higher resitivity and/or the higher relative dielectric constant, concurrently the longer relaxation time constant of the rotor surface materials make the motor speed get higher speed. In case of discrete coated rotor surface it is found that the motor speed was increased logarithmically as narrow as width of the discrete coated Ti. And the degree of width of discrete coated Ti to the axial direction of the rotor was $60^{\circ}$ and $150^{\circ}$, the motor has got a 125% higher than that at the degree of $0^{\circ}$.

• International Journal of Reliability and Applications
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• v.12 no.1
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• pp.61-77
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• 2011

One of the most important problems in the estimation of the parameter of the failure model, is the cost of experimental sampling units, which can be reduced by using any prior information available about ${\theta}$, and devising a two-stage pooling shrunken estimation procedure. We have proposed an estimator of the reliability function (R(t)) of the exponential model using two-stage time censored data when a prior value about the unknown parameter (${\theta}$) is available from the past. To compare the performance of the proposed estimator with the classical estimator, computer intensive calculations for bias, mean squared error, relative efficiency, expected sample size and percentage of the overall sample size saved expressions, were done for varying the constants involved in the proposed estimator (${\tilde{R}}$(t)).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1256-1259
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• 2006

The purpose of this study was to investigate the current status and influence factor in measuring the dynamic stiffness of damping materials. The property of the dynamic stiffness of damping materials was tested and analysed in condition such as the size of test samples and the change of relative humidity in heating chamber. Test results showed that the dynamic stiffness of after-heating was lower than that of before-heating in most samples and the change of relative humidity in heating chamber got little influence of the dynamic stiffness. The resonant frequency of test sample decreased $2{\sim}7Hz$ as the decrease of the size of sample. Because it was increased that total mass per unit area of sample, the change of dynamic stiffness had little influence.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.10a
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• pp.39-40
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• 2003

1) Using a developed high-frequency induction heated sintering method, the rapid densification of WC-Co hard materials was accomplished using ultra fine powders with 260 nm size within 1 minute. 2) The relative density of the composite was 99.5% for the applide pressure of 60MPa and the induced current for 90% output of total capacity. 3) The grain size of WC-Co hard materials is about 260nm and the average thickness of the binder phase determined is about 11nm. The fracture toughness and the hardness of this work 12 $MPa{\cdot}nm^2$, respectively. 4) Using pressureless sintering, we produced dense WC-Co hard materials with a relative density of 97% without applying pressure.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.671-677
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• 1999

This study has been performed to investigate REW(relative electrode wear) in condition of vari-ous pulse-on duration using the copper and graphite electrode with change of the electrode size on the heat treated STD11 which is extensively used for metallic molding steel with the EDM. The results obtained are as follows; a) Graphite has much benefits than copper electrode when rapid machining is done without electrode wear, b) Neative REW result from the electrode that is very liable attach to decomposition carbide c)Increasing of machining time cause to increase wear length of the copper electrode and decrease wear length of the graphite electorde d)The more pulse-on duration copper electrode has the less REW. e) The edge portion of the electorde wears remarkably at the beginning of machining,.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.4
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• pp.167-173
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• 2022

Investors must adopt profitable investment opportunities to maximize their wealth. Almost all investment, finance, engineering economics textbooks explain that net present value (NPV) measures the profitability (or value) of investment opportunities in absolute size, and internal rate of return (IRR) measures the profitability of investment opportunities in relative proportions. However, NPV is a measure of the relative size of the return on investment opportunity to do-nothing alternative. Moreover, IRR can occur in multiple investment opportunities and may not exist. To make matters worse, IRR and NPV also have conflicting problems in accept-or-reject decisions. In this study, the reason why NPV and IRR cannot accurately measure the profitability of investment opportunities is identified, and fundamental characteristics that investment opportunity profitability measures should have are presented.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1004-1010
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• 1998

Effects of reaction conditions such as power input and feeding time and feeding mode of reactants on the reaction crystallization of lanthanum oxalate in semi-batch reactor were investigated experimentally. Even though the crystal size distribution of lanthanum oxalate was always monomodal, its mean crystal size was significantly varied with the reaction conditions. As the power input and reactant feeding rate increased, the mean crystal size was reduced and the relative induction time was prolonged. The mean crystal size produced in oxalic acid feeding mode was smaller than that in lanthanum chloride feeding mode, but the trend of the relative induction time with the feeding mode was reverse to that of the mean crystal size. The crystal morphology of lanthanum oxalate, which was produced within the ranges of the reaction conditions in our experiment, was maintained as a needle shape.

• Journal of Animal Science and Technology
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• v.56 no.5
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• pp.20.1-20.5
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• 2014

An experiment was conducted to evaluate the effect of form and particle size of feed supplemented with L-threonine on growth performance, carcass characteristic and blood biochemical parameters of broiler chickens. The experimental design was a $2{\times}2{\times}2$ factorial arrangement of treatments evaluating two feed forms (pellet or mash), two feed particle sizes (fine or course), and two inclusion rates of dietary L-threonine (with or without) which adopted from 7 to 42 days of age. In this experiment, 360 a day old chicks in two sexes were assigned in each treatment and each experimental unit was included 15 chicks. Feed consumption and weight gain were measured weekly. At 35 days of age, blood samples were taken to analysis blood biochemical parameters. At the end of the experimental period, two birds were slaughtered in each treatment and carcass analysis was carried out. The results showed that the effect of feed form on body weight gain and feed intake in whole of experimental period was significant (P < 0.05). Broilers fed pelleted diets had more weight gain than the mash group. Growth performance parameters were not affected by feed particle size and dietary L-threonine supplementation in whole of experimental period (P > 0.05). The results of carcass analysis showed that liver and gizzard relative weights were influenced by feed form (P < 0.05). However, pancreas and liver relative weights were affected by feed particle size and dietary L-threonine supplementation, respectively (P < 0.05). Triglyceride and VLDL levels were affected by feed form and dietary L-threonine supplementation (P < 0.05). The effect of feed particle size on blood biochemical parameters was not significant (P > 0.05). In conclusion, the experimental results indicated that feed form increased feed consumption and weight gain in whole of experimental period (1 to 42 days of age) while feed particle size and dietary L-threonine had no effect on broiler performance.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2004.11a
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• pp.419-420
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• 2004