• Journal of Korean Society of Industrial and Systems Engineering
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• v.10 no.16
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• pp.101-106
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• 1987

Statistical control charts are useful tools to monitor and control the manufacturing processes and are widely used in most Korean industries. Many Korean companies, however, do not always obtain desired results from the traditional control charts by Shewhart such as the $\bar{X}$-chart, $\bar{X}$-chart, $\bar{X}$-chart, etc. This is partly because the quality charterstics of the process are not distributed normally but are skewed due to the intermittent production, small lot size, etc. In Shewhart $\bar{X}$-chart. which is the most widely used one in Kora, such skewed distributions make the plots to be inclined below or above the central line or outside the control limits although no assignable causes can be found. To overcome such shortcomings in nonnormally distributed processes, a distribution-free type of confidence interval can be used, which should be based on order statistics. This thesis is concerned with the design of control chart based on a sample median which is easy to use in practical situation and therefore properties for nonnormal distributions may be easily analyzed. Control limits and central lines are given for the more famous nonnormal distributions, such as Gamma, Beta, Lognormal, Weibull, Pareto, Truncated-normal distributions. Robustness of the proposed median control chart is compared with that of the $\bar{X}$-chart; the former tends to be superior to the latter as the probability distribution of the process becomes more skewed. The average run length to detect the assignable cause is also compared when the process has a Normal or a Gamma distribution for which the properties of X are easy to verify, the proposed chart is slightly worse than the $\bar{X}$-chart for the normally distributed product but much better for Gamma-distributed products. Average Run Lengths of the other distributions are also computed. To use the proposed control chart, the probability distribution of the process should be known or estimated. If it is not possible, the results of comparison of the robustness force us to use the proposed median control chart based oh a normal distribution. To estimate the distribution of the process, Sturge's formula is used to graph the histogram and the method of probability plotting, $\chi$$^2$-goodness of fit test and Kolmogorov-Smirnov test, are discussed with real case examples. A comparison of the proposed median chart and the $\bar{X}$ chart was also performed with these examples and the median chart turned out to be superior to the $\bar{X}$-chart.

• Journal of Magnetics
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• v.2 no.1
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• pp.25-27
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• 1997

Ferrite tile absorber is of great concern for the application to anechoic chambers due to the growing demand of EMI or EMC measurements. This paper investigates the magnetic, dielectric and microwave absorbing properties of a Ni-An ferrite for the purpose. A design chart was constructed with the solutions of impedance-matching equation in the radio frequencies (30 MHz - 1 GHz). The material parameters for zero-reflection are predicted from the chart. The magnetic and dielectric properties of sintered Ni-Zn ferrite is found to be well suited for this requirements. A superior microwave absorbing properties (frequency band and absorber thickness) of the samples are demonstrated.

• Journal of Korean Society for Quality Management
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• v.21 no.2
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• pp.232-241
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• 1993

The objective of this study is to develop an algorithm in the consideration of importance Weight and desirable shape of specific department in the computerized layout planning. Quantitative relationship chart between each department was used. It is decided that the priority among the department as to variable factors and the optimum quantitative relationship chart was obtained using by the Weighting method. The algorithm presented in this study could generate more practical layout for the actual design problem.

• Journal of Korean Society for Quality Management
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• v.23 no.4
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• pp.1-12
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• 1995

Sample skewness has not received much attention from researchers to design a control chart. In this paper, control charts based on two skewness measures are studied to control a manufacturing process. One skewness measure is the third central moment about mean, the other is the third L-moment which is a linear combination of order statistics. Since the exact sampling distributions of two skewness measures are unknown, empirical sampling distributions are studied using simulation. The sampling distributions are used to design control charts for skewness and performance of two skewness measures is compared.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1844-1845
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• 2007

A CUSUM control chart was used to monitor semiconductor plasma equipment. The performance of plasma monitoring was evaluated with various combinations of design variables involved in CUCUM control chart. Experimental data collected by using a real-time matching monitoring system include electrical positions of impedance and phase positions, and reflected power. The evaluation revealed that by determining specific design variables plasma states could be more strictly monitored.

• Journal of the Korea Safety Management & Science
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• v.1 no.1
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• pp.123-134
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• 1999

There are several models for process quality assurance by quality system (ISO 9000), process capability analysis, acceptance control chart and so on. When a high level process capability has been achieved, it takes a long time to monitor the process shift, so it is sometimes necessary to develop a quicker monitoring system. To achieve a quicker quality assurance model for high-reliability process, this paper presents a model for process quality assurance when the fraction nonconforming is very small. We design an acceptance control chart based on variable quality characteristic and time-censored accelerated testing. The distribution of the characteristics is assumed to be normal or lognormal with a location parameter of the distribution that is a linear function of a stress. The design parameters are sample size, control limits and sample proportions allocated to low stress. These paramaters are obtained under minimization of the relative variance of the MLE of location parameter subject to APL and RPL constraints.

• Current Optics and Photonics
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• v.1 no.4
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• pp.378-388
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• 2017

We present a graphical method for determining a pair of optical materials and powers to design an achromatic and athermal lens system with corrected Petzval curvature. To graphically obtain the solutions, a three-dimensional (3D) glass chart is proposed. Even if a particular material combination is unavailable, we can select an element suitable for a specific lens and continuously change the element powers of an equivalent single lens for aberrations correction. Thus, we can iteratively identify the materials and powers on a 3D glass chart. By designing a fisheye lens using this method, an achromatic and athermal system with flat Petzval curvature is obtained, over the specified waveband and temperature ranges.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7C
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• pp.587-593
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• 2010

In this paper we design an irregular low-density parity-check (LDPC) code for multiple-input multiple-output (MIMO) system, using a simple extrinsic information transfer (EXIT) chart method. The MIMO systems considered are optimal maximum a posteriori probability (MAP) detector. The MIMO detector and the LDPC decoder exchange soft information and form a turbo iterative receiver. The EXIT charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the MIMO detector. It is shown that the performance of the designed LDPC code is better than that of conventional LDPC code which was optimized for either the Additive White Gaussian Noise (AWGN) channel or the MIMO channel.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.127-137
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• 1989

This paper describes hardware flow-chart and SDL-II, which are register-transfer level, to automate logic design. Hardware flow-chart specifies behavioral and structural charaterstics of generalized FSMs (Finite State Machine) usin the modified ASM (Algorithmic State Machnine) design techniques. SDL-II describes the hardware flow-chat which specifies the control and the data path of ASIC(Application Specific IC). Also many examples are enumerated to illustrate the features of hardware flow-chart and SDL-II.

• Communications for Statistical Applications and Methods
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• v.17 no.3
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• pp.357-365
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• 2010

This paper considers the integrated process control procedure for detecting special causes in an IMA(1,1) noise process that is being adjusted using a minimum mean squared error adjustment. As a SPC procedure, we use a GLR chart for detecting special causes whose effects are the sustained shift or the sustained drift in the process mean, and the sustained shift in the process variance. For the design of the GLR chart, we derive expressions for the control limit which accurately satisfies the given in-control ARL.