• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.45
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• pp.237-246
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• 1998

In most statistical process control(SPC), control charts are used in which samples are taken and a suitable statistic is determined and plotted. In these control charts, control limits, ${\mu}{\pm}textsc{k{\sigma}}$, from which a decision is made are mostly ${\mu}{\pm}3{\sigma}$ and current literature in control charts are mainly concerned with detecting a shift in the mean. Therefore, when $\sigma$ is increased considerably after a long time, using control limits set at the first time causes a great deal of economic loss. In this paper the solutions to determine new control limits which maximizes the profit per unit produced and reduce $\sigma$ to economically optimal level for a certain cost when $\sigma$ is increased due to process deterioration are proposed. By applying new control limits, $\alpha$ error decreases considerably compared to apply initial control limits when $\sigma$ is increased due to process deterioration. Therefore, false alarm investigation cost drops down to the level of initial a error. And also this solution provides useful information regarding replacement of a process when the process is reviewed regularly.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.1 s.160
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• pp.119-130
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• 2007

The objects of this study were to investigate responses and peculiarity during local cooling by parts of the human body and to show permissible safety limits without injurious to his health because of excessive cooling when he works hot environments. It were measured rectal temperature, skin temperature, heart rate, total body weight loss, local sweat in back and thigh, clothing microclimate and subjective sensation on 8 subjects and cooling parts were head, neck, chest, abdomen, back, waist, hip, upper arm, forearm, hand, thigh, calf and foot. According to above-mentioned the first experiment, we chose permissible safety limits by parts of the human body for one hour. In the second experiment, it was showed permissible safety limits by parts which examined their safety about health through 4 hours cooling test on 3 subjects. The results are as follows: 1. As a result of the first experiment, we chose permissible safety limits by parts, as follows, head $25^{\circ}C$, neck $20^{\circ}C$, chest $27^{\circ}C$, abdomen $25^{\circ}C$, back $20^{\circ}C$, waist $20^{\circ}C$, upper arm $20^{\circ}C$, forearm $20^{\circ}C$, hand $23^{\circ}C$, thigh $20^{\circ}C$, calf $20^{\circ}C$ and foot $23^{\circ}C$ in $37^{\circ}C$, 50%R.H. environment for 1 hour. 2. As a result of the second experiment, cooling on these safety limits temperatures except chest didn't have a bad effect on health. So it was proved that right permissible safety limits of chest was $28^{\circ}C$. From these results, it has been suggested that skin temperature didn't fall below permissible safety limits when human body was to be cool by parts.

• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.337-348
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• 2023

The optimization of reinforced concrete (RC) cantilever retaining walls is a complex problem and requires the use of advanced techniques like metaheuristic algorithms. For this purpose, an optimization model must first be developed, which involves mathematical complications, multidisciplinary knowledge, and programming skills. This task has proven to be too arduous and has halted the mainstream acceptance of optimization. Therefore, it is necessary to unravel the complications of optimization into an easily applicable form. Currently, the most commonly used method for designing retaining walls is by following the proportioning limits provided by the ACI handbook. However, these limits, derived manually, are not verified by any optimization technique. There is a need to validate or modify these limits, using optimization algorithms to consider them as optimal limits. Therefore, this study aims to propose updated proportioning limits for the economical design of a RC cantilever retaining wall through a comprehensive parametric investigation using the genetic algorithm (GA). Multiple simulations are run to examine various design parameters, and trends are drawn to determine effective ranges. The optimal limits are derived for 5 geometric and 3 reinforcement variables and validated by comparison with their predecessor, ACI's preliminary proportioning limits. The results indicate close proximity between the optimized and code-provided ranges; however, the use of optimal limits can lead to additional cost optimization. Modifications to achieve further optimization are also discussed. Besides the geometric variables, other design parameters not covered by the ACI building code, like reinforcement ratios, bar diameters, and material strengths, and their effects on cost optimization, are also discussed. The findings of this investigation can be used by experienced engineers to refine their designs, without delving into the complexities of optimization.

• IE interfaces
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• v.17 no.1
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• pp.1-12
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• 2004

In a modern semiconductor device manufacturing industry, statistical bin limits on wafer level test bin data are used for minimizing value added to defective product as well as protecting end customers from potential quality and reliability excursion. Most wafer level test bin data show skewed distributions. By Monte Carlo simulation, this paper evaluates methods and sample size effect regarding determination of statistical bin limits. In the simulation, it is assumed that wafer level test bin data follow the Poisson distribution. Hence, typical shapes of the data distribution can be specified in terms of the distribution's parameter. This study examines three different methods; 1) percentile based methodology; 2) data transformation; and 3) Poisson model fitting. The mean square error is adopted as a performance measure for each simulation scenario. Then, a case study is presented. Results show that the percentile and transformation based methods give more stable statistical bin limits associated with the real dataset. However, with highly skewed distributions, the transformation based method should be used with caution in determining statistical bin limits. When the data are well fitted to a certain probability distribution, the model fitting approach can be used in the determination. As for the sample size effect, the mean square error seems to reduce exponentially according to the sample size.

• Journal of the Korean Institute of Educational Facilities
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• v.13 no.4
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• pp.31-42
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• 2006

This study is about an analysis of the relation between the degree of cognition of student's acts within limits when coping with several types of disaster and the degree of cognition of damage by disasters in the method of multiple regression analysis. The dependent variable is the degree of cognition of student's acts within limits and the independent variable is the degree of cognition of damage by disasters such as heavy snow, typhoon, heavy rain, heat, and yellow sand. A survey of graduates of metropolitan area high-schools has found that there are no difference between girls and boys of the degree of cognition of student's acts within limits when coping with disasters. This study finds that the independent variable, which are playgrounds, animals and plants, streets and roads, altitude and incline, gives positive effect to the degree of cognition of student's acts within limits when coping with typhoon or heavy rain in order. The study also finds that the degree of cognition of student's acts within limits when coping with heavy snow is affected positively by streets and roads, playgrounds, altitude and incline in order. It also shows that there are factors that has an effect to the degree of cognition of student's acts within limits when coping with yellow sand and heat. This study proposes suggestions to facility plans based on these facts discovered.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.67-76
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• 1992

A procedure to determine the axle load limits of asphalt concrete pavements are proposed in this study. Axle load limits are determined by calculating maximum tensile strains at the bottom of the asphalt stabilized base layer and maximum vertical strains at the top of the subgrade. In order to investigate the efficiency of axle configuration, calculated influence line of wheel load on domestic expressway pavement system is used. Limiting strains are selected through the analysis of conventional failure criteria. From the analysis of axle load limits about axle composition(single-axle, tandem-axle, tridem-axle), it is found that the axle load limits of tandem-axle and tridem-axle can be calculated by muitipling the axle load limits of single-axle by axle numbers and that axle load limits are closely related to the thickness of each layer of pavement structure. It is also found that the axle load limits by tensile strains are more critical than those by vertical strains on asphalt concrete pavement models of YOUNG-DONG, KYONG-IN and KYONG-BU expressways.

• Kyungpook Mathematical Journal
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• v.19 no.2
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• pp.257-260
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• 1979

We show that the condition S of Sidon is sufficient for the integrability of the limit of Rees-$Stanojevi{\acute{c}$ cosine sums $g_n(x)={\frac{1}{2}}{\limits\sum^{n}_{k=0}}{\Delta}a_k+{\limits\sum^{n}_{k=1}}{\limits\sum^{n}_{j=k}}{\Delta}a_j\;cos\;kx$.

• Journal of the Korean Mathematical Society
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• v.50 no.3
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• pp.641-693
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• 2013

We show that the optimistic limits of the colored Jones polynomials of the hyperbolic knots coincide with the optimistic limits of the Kashaev invariants modulo $4{\pi}^2$.

• Honam Mathematical Journal
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• v.30 no.2
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• pp.233-246
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• 2008

In this paper, we obtain the general solution of the following cubic type functional equation and establish the stability of this equation (0.1) $kf({{\sum}\limits^{n-1}_{j=1}}x_j+kx_n)+kf({{\sum}\limits^{n-1}_{j=1}}x_j-kx_n)+2{{\sum}\limits^{n-1}_{j=1}}f(kx_j)+(k^3-1)(n-1)[f(x_1)+f(-x_1)]=2kf({\sum\limits^{n-1}_{j=1}}x_j)=K^3{\sum\limits^{n-1}_{j=1}[f(x_j+x_n)+f(x_j-x_n)]$ for any integers k and n with k ${\geq}$ 2 and n ${\geq}$ 3.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.145-150
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• 2017

This paper present a unified method of steady state performance analysis and limits characteristics of an autonomous three-phase self-excited induction generator (SEIG) driven by a wind turbine under different types of loads and speeds. The proposed method is based on a new mathematical function to solve for the real and imaginary components of the complex equation of the mathematical model. Performances limits, regulation and characteristics of different configurations will be thoroughly examined and compared. The proposed system will be modeled and simulated and the performance limits characteristics will be compared with variable speed and variable capacity.