• The Mathematical Education
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• v.50 no.4
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• pp.489-505
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• 2011

This study is an analysis on the focus of textbooks regarding the statistical chapters of "measures of representative(central tendency) and of the spread". Applying the summary-concept criteria of Juhyeon Nam(2007), 4 kinds of aspect of the chapter; (1) definition and its teleological validity of the measures of representative, (2) definition and practical value of the measures of spread (3) distributional form on the measures of representative and of spread (4) location and scale preservation or invariance of the measures of representative and of spread were observed. On the measures of representative, some definitions were insufficient to check the teleological validity of the measure. Most definitions of the measure of spread were based on the practical view points but no preparation for the future statistical inferences were found even by implication. Some books mention about the measures of representative and of spread for distributions, but we could not find any comments on the correspondence between the sample mean and the expectation of a distribution or population mean. However it is stimulant that some books check the validity of corresponding measures with the location and scale preservation or invariant property, that were not found in the previous curriculum.

• The Korean Journal of Financial Studies
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• v.2 no.1
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• pp.127-144
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• 1995

Previous literature in financial economics documents the existence of a liquidity premium in expected returns, measured by the bid-ask spread. This study provides a more comprehensive test of the egect of liquidity on common stock returns by including trading volume as an additional liquidity measure. we find that trading volume is a relevant measure of liquidity, and affects expected returns even aher controlling for the effects of systematic risk, firm size, and the relative bid-ask spread. We also find that trading volume complements the bid-ask spread as a liquidity measure, and provides additional information about the liquidity premium. The liquidity effect emerges in non-January months as a volume effect, in addition to the spread effect in January documented by Eleswarapu and Reinganum(1993).

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.4
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• pp.195-197
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• 2006

When we measure electrical impedance of a small object, such as an electronic component, external interference or jamming signal can be rejected by shielding the object. However, when we measure impedance of a large object, such as a human body, shielding is not easy and severe error due to the external interference could be introduced. In this paper, spread spectrum technique applicable to bioimpedance measurements for rejecting external interference without shielding is introduced. The improvement in signal-to-jamming ratio by the spread spectrum technique was experimentally confirmed.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.200-207
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• 1999

To increase dimensional accuracy of strip width, model to compensate width spread during roughing mill has been developed. To measure the amount of width spread during the production rolling more precisely, special roughing rolling procedures for the horizontal rolling and dog-bone rolling were designed in the actual production mill. From the operational data analysis, it is known that the prime factors influencing on the width spread were strip width, strip thickness, edging amount, number of pass and type of edger roll etc., Based upon the statistical analysis of rolling data, new models which can predict width spread during horizontal rolling and dog-bone rolling were developed and tested on the actual processing conditions for the reliability. The application test showed that newly developed model gave fairly accurate predictions on the width spread during roughing passes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.68-74
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• 2000

Experimental investigation on flame spread along suspended droplet arrays have been conducted with various droplet spacings and ambient air velocities. Especially, an opposed air stream is introduced to simulate fundamental flame spread behaviors in spray combustion. High-speed chemiluminescence imaging technique of OH radicals has been adopted to measure flame spread rates and to observe various flame spread behaviors. The fuel used is n-Decane and the air velocity varies from 0 to 17cm/s. The pattern of flame spread is grouped into two: a continuous mode and an intermittent one. It is found that there exists droplet spcings, above which flame spread does not occur. The increase of ambient air velocity causes the limit droplet spacing of flame spread to become small due to the increase of apparent flame stretch. As the ambient air velocity decreases, flame spread rate increases and then decreases after taking a maximum flame spread rate. This suggests that there exists a moderate air flowing to give a maximum flame spread rate due to enhanced chemical reaction by the increase of oxidizer concentration.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.833-836
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• 1987

The error probability for coherent frequency-hopped spread-spectrum multiple-access communications is computed. We employ PSK as a modulation scheme. The channel capacity is performance measure and the minimum bit signal-to-noise ratio for reliable communications is obtained.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.10
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• pp.994-1001
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• 2009

CSS (Chirp Spread Spectrum) specified in IEEE 802.15.4a can be used for ranging applications. In this paper, we apply the CSS to estimate the coordinates of a mobile robot. Four anchor nodes are installed at known positions and a tag node is attached to the target mobile robot. By CSS ranging, we measure the distances between each anchor and the tag node. Based on the measured distances, the coordinates of the mobile robot can be calculated by the method of trilateration. However the calculated coordinates are not accurate because of the errors of the measured distances. Therefore we propose an algorithm for reducing the effect of the errors. The proposed algorithm is executed with the extended Kalman filter. Through localization experiments, we show the performance of the proposed algorithm and the accuracy of the estimated position.

• Communications for Statistical Applications and Methods
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• v.6 no.2
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• pp.383-395
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• 1999

This study is concerned with the evaluation of predictive ability of classification models with ordered multiple categories. If categories can be ordered or ranked the spread of misclassification should be considered to evaluate the performance of the classification models using loss rate since the apparent error rate can not measure the spread of misclassification. Since loss rate is known to underestimate the true loss rate the bootstrap method were used to estimate the true loss rate. thus this study suggests the method to evaluate the predictive power of the classification models using loss rate and the bootstrap estimate of the true loss rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.6
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• pp.453-460
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• 1988

The error probability for coherent frequency-hopped spread-spectrum multiple-access communications is computed by using characteristic function method. We employ PSK as a modulation scheme. The channel capacity is performance measure and the minimum bit signal-to-noise ratio for reliable communications is obtained.

• Journal of Yeungnam Medical Science
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• v.39 no.4
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• pp.344-346
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• 2022

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread worldwide, leading the World Health Organization to declare coronavirus disease 2019 (COVID-19) a pandemic. To curb the unchecked spread of SARS-CoV-2 infection, most countries have enforced travel restrictions. However, it is debatable whether such restrictions are effective in containing infections and preventing pandemics. Rather, they may negatively impact economies and diplomatic relationships. Each government should conduct an extensive and appropriate analysis of its national economy, diplomatic status, and COVID-19 preparedness to decide whether it is best to restrict entering travelers. Even if travelers from other countries are allowed entry, extensive contact tracing is required to prevent the spread of COVID-19. In addition, governments can implement "travel bubbles," which allow the quarantine-free flow of people among countries with relatively low levels of community transmission. An accurate evaluation of the benefits and losses due to entry restrictions during the COVID-19 pandemic would be helpful in determining whether entry restrictions are an effective measure to reduce the spread of infection in future pandemics.