• Journal of Korean Institute of Industrial Engineers
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• v.16 no.1
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• pp.1-15
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• 1990

An AQL type variables sampling system with switching rules is proposed. Comparative studies of existing variables sampling standards - MIL-STD-414, ANSI Z1.9, ISO 3951, and BS 6002 - are made, and simulation studies on switching procedures are conducted. Based on comparative and simulation studies, a variables sampling standard for Korean industry is proposed. The master sampling tables of the proposed standard are taken from the variables standard ANSI Z 1. 9 and the switching rules are matched to the attributes standard KS A 3109 to enable us to move between the proposed variables standard and KS A 3109. Composite OC and ASN curves of the proposed standard are calculated for selected combinations of lot sizes and AQL's and they are compared with those of ANSI Z1.9.

• Journal of the Korea Society for Simulation
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• v.8 no.3
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• pp.77-89
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• 1999

Simulating rare events, such as probability of cell loss in ATM networks, machine failure in highly reliable systems, requires huge simulation efforts due to the low chance of occurrence. Importance Sampling (IS) has been applied to accelerate the occurrence of rare events. However, it has a drawback of effective biasing scheme to make the estimator of IS unbiased. Adaptive Importance Sampling (AIS) employs an estimated sampling distribution of IS to the system of interest during the course of simulation. We propose Nonparametric Adaptive Importance Sampling (NAIS) technique which is nonparametrical version of AIS. We test NAIS to estimate a probability of rare event in M/M/1 queueing model. Comparing with classical Monte Carlo simulation, the computational efficiency and variance reductions gained via NAIS are substantial. A possible extension of NAIS regarding with random number generation is also discussed.

• Journal of Biomedical Engineering Research
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• v.10 no.1
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• pp.33-42
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• 1989

The doppler effect is used for measuring the velocity of the blood flow in artery. Because of the range information, the pulsed doppler system is most commonly used. In this paper, we propose a new two-dimensional(2-D) pulsed Doppler system. Which uses second-order sampling method and serial processing. The proposed system using second-order sampling method eliminates in-phase, quadrature-phase balancing problem at demodulator of quadrature detection method. In addition, the new pulsed 2-D doppler system eliminates balancing problem of channels of 2-D doppler system because of serial processing.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.10
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• pp.994-1000
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• 2013

Conventional MIMO system is required to a number of RF chains as much as a number of antennas. If the number of antennas increased then the number of RF chains increased. Therefore, it is difficult to apply conventional MIMO system to mobile terminals with limited power. In this paper, we propose a TDM(time division multiplexing)-based single RF chain MIMO system. The outcome shows that performance of the proposed system is similar to conventional MIMO system using multiple RF chains when STO is corrected by phase angle estimation and the synchronizing signal of received signal. Therefore, it is possible to implement the MIMO-OFDM system of low power and complexity through a single RF chain.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.79-81
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• 1992

This paper describes the design of an adaptive closed circuit anesthesia controller based on a multiplexed mass spectrometer system. The controller deals with measurement deterioration caused by measurement delay and rise time through a tong catheter as well as long sampling times due to the multiplexed measurements. Measurement data is extrapolated between sampling periods to increase the estimation convergence rate. A multiple-step-ahead predictive control algorithm is used to calculate intermediatc control inputs between sampling intervals. Simulations are used to validate the designed controller.

• Communications for Statistical Applications and Methods
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• v.12 no.1
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• pp.229-240
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• 2005

This study described the application of constructivism and information technology for teaching simple random sampling. We considered more student's participation, more interaction, and more flow in their introductory statistics class. In addition, we presented a web-based teaching and learning system for simple random sampling to demonstrate.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.553-556
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• 1996

The cell loss probability recommended in the B-ISDN is in the range of 10$^{-8}$ ~ 10$^{-12}$ . When a simulation technique is used to analyze the performance of the ATM switching system, an enormous amount of computer time is required. In this study, we derive an importance sampling simulation technique that can be used to evaluate the loss probability obtained by the importance sampling simulation is very close to that obtained by the ordinary simulation and the computer time can be reduced drastically by the importance sampling simulation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.59
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• pp.97-103
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• 2000

This study considers the design of life test sampling inspection plans by attributes for failure rate level qualification at selected confidence level. The lifetime distribution of products is assumed to be exponential. MIL-STD-690C and KS C 6032 standards provide this procedures. But these procedures have some questions to apply in the field. The cost of test and confidence level($1-{\beta}$ risk) are the problem between supplier and user. So, we suggest that the optimal life test sampling inspection plans using expected cost model considering product cost, capability, environmental test cost, etc.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.21
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• pp.81-90
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• 1990

In stratified random sampling a simple random sample must be taken in each stratum to reduce the maximum gain in precision given the minimum cost. The purpose of this paper is to deal with the propertics of the estimates and variances and obtain the economic design of stratified random sampling through the optimum allocation of the sample sizes. In addition, the between stratum variation and the within stratum variation is stratifying the population are described.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.4
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• pp.12-22
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• 2003

The purposes of this study are to investigate the conformity of Korean Standards(KS) according to agreement on WTO/TBT, and to propose systematic frameworks of preparation, adoption, and application for KS in our enterprises. Significant changes in this establishment, revision, and abrogation include the following divisions; i) statistics-vocabulary and symbols, ii) Shewhart control chart, iii) statistical interpretation of data, iv) sampling procedures for inspection by attributes, v) sequential sampling plans for inspection.