• 산업경영시스템학회지
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• 제41권2호
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• pp.117-132
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• 2018

There always exist nonzero inspection errors whether inspectors are humans or automatic inspection machines. Inspection errors can be categorized by two types, type I error and type II error, and they can be regarded as either a constant or a random variable. Under the assumption that two types of random inspection errors are distributed with the "uniform" distribution on a half-open interval starting from zero, it was proved that inspectors overestimate any given fraction defective with the probability more than 50%, if and only if the given fraction defective is smaller than a critical value, which depends upon only the ratio of a type II error over a type I error. In addition, it was also proved that the probability of overestimation approaches one hundred percent as a given fraction defective approaches zero. If these critical phenomena hold true for any error distribution, then it might have great economic impact on commercial inspection plans due to the unfair overestimation and the recent trend of decreasing fraction defectives in industry. In this paper, we deal with the same overestimation problem, but assume a "symmetrical triangular" distribution expecting better results since our triangular distribution is closer to a normal distribution than the uniform distribution. It turns out that the overestimation phenomenon still holds true even for the triangular error distribution.

• 한국초등수학교육학회지
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• 제18권2호
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• pp.257-278
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• 2014

0의 개념 및 0이 포함된 사칙계산은 학생들이 수학 학습에서 경험하는 어려운 내용 중 하나이다. 이는 0의 발생 과정 및 0을 포함하는 계산에 대한 인식 등에서 수학사적으로도 확인되는 바이다. 따라서 수학 교수 학습 시 학생들의 0 개념에 대한 올바른 이해와 0을 포함하는 계산 절차의 숙달을 위한 적절한 지도가 이루어져야 함을 함의한다. 본 연구는 선행 연구에 기초하여 학생들이 경험할 것으로 예상되는 0처리 오류가 주의 깊게 지도되고 있는지 조사하고 바람직한 지도 방향을 모색하는 것을 목표로 한다. 이를 위해 교과용 도서 분석을 통해 실제 수학 지도 시 0의 개념 및 0을 포함하는 계산이 적절하게 지도되고 있는지 검토하였다. 분석 결과, $0{\div}$수, 몫의 중간에 0이 포함되는 나눗셈의 지도가 미흡한 것으로 나타났다. 이에 관련 내용의 학습을 목표로 하는 활동지를 구성하고, 0처리 오류 방지를 위한 시사점을 제시하였다.

• 대한수학교육학회지:학교수학
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• 제8권4호
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• pp.397-415
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• 2006

이 연구는 사칙 계산 과정에서 초등학생들이 공통적으로 0을 처리하는 것의 어려움을 느낀다는 점에 착안하여, 학생들의 0처리 오류의 기원을 찾고자 수학사 및 교과서 분석을 시도하였다. 그 결과 오늘날의 사람들이 가지고 있는 0에 대한 어려움이 역사적인 근원을 가지고 있음을 밝혀내었다. 또한 0의 지도라는 관점에서 수학 교과서 및 익힘책을 분석한 결과, 0의 도입 시기와 방법이 십진기수법에서의 0의 역할을 인식시키기에 미흡한 점이 있으며, 0을 대상으로 하는 간단한 계산이 부분적으로 다루어지고 있지 않음을 밝혀내었다. 또한 학생들이 자주 범하는 0처리 오류를 예방하기 위한 문항이 체계적으로 제시되어 있지 않았다. 이러한 문제점을 극복하기 위해, 이 연구에서는 일렬, 독일 교과서 등을 참고하여 0의 지도와 관련된 세 가지 방안을 제안하였다.

• 한국통신학회논문지
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• 제36권12C호
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• pp.753-758
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• 2011

The constant modulus algorithm (CMA) widely used in blind equalization applications minimizes the averaged power of constant modulus error (CME) defined as the difference between an instant output power and a constant modulus. In this paper, a decision feedback version of the linear blind algorithm based on maximization of the zero-error probability for CME is proposed. The Gaussian kernel of the maximum zero-error criterion is analyzed to have the property to cut out excessive CMEs that may be induced from severely distorted channel characteristics. Decision feedback approach to the maximum zero-error criterion for CME is developed based on the characteristic that the Gaussian kernel suppresses the outliers and this prevents error propagation to some extent. Compared to the linear algorithm based on maximum zero-error probability for CME in the simulation of blind equalization environments, the proposed decision feedback version has superior performance enhancement particularly in cases of severe channel distortions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.236-239
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• 1988

Prediction errors generated by motion compensated coding are coded with transform coding techniques as DCT. The performance of transform coding techniques are lowered mainly due to the source characteristics with a great deal of zero populations and plus-minus sign changes, i.e., low correlation. In this paper a transform coding scheme which adopts a decomposition of prediciton errors into two sources is proposed and compared its performance with conventional scheme.

• Journal of the Korean Statistical Society
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• 제25권2호
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• pp.235-241
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• 1996

The ordinary least squares estimator of the disturbance variance in the linear regression model with stationary errors is shown to be asymptotically unbiased when the error process has a spectral density bounded from the above and away from zero. Such error processes cover a broad class of stationary processes, including ARMA processes.

• Journal of Positioning, Navigation, and Timing
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• 제9권1호
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• pp.33-42
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• 2020

In Integration Approach (IA)-based Pedestrian Dead Reckoning (PDR), it is important to detect the exact zero-velocity of the foot with an Inertial Measurement Unit (IMU). By detecting zero-velocity during the stance phase of the foot touching the ground and executing Zero-velocity UPdaTe (ZUPT) at the exact time, stable navigation information can be provided by the PDR. When the pace is fast, however, it is not easy to accurately detect the zero-velocity because of the small stance phase interval and the large signal variance of the corresponding interval. Incorrect zero-velcity detection greatly causes navigation errors of IA-based PDR. In this paper, we propose a method to detect the zero-velocity stably even at high speed by novel buffering of IMU's output data and signal processing of the buffer. And we design a PDR based on this. By analyzing the performance of the proposed Zero-Velocity Detection (ZVD) algorithm and ZVD-based PDR through experiemnts, we confirm that the proposed method can provide accurate navigation information of pedestrians such as firefighters in the indoor space.

• 품질경영학회지
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• 제25권1호
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• pp.69-79
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• 1997

We consider the semiparametric linear errors-in-variables model: yi=(${\alpha}+{\beta}ui+{\varepsilon}i$, xi=ui＋${\varepsilon}i$ i=1, …, n where (xi, yi) stands for an observation vector, (ui) denotes a set of incidental nuisance parameters, (${\alpha}$ , ${\beta}$) is a vector of regression parameters and (${\varepsilon}i$, ${\delta}i$) are mutually uncorrelated measurement errors with zero mean and finite variances but otherwise unknown distributions. On the basis of a simple small-sample low-noise a, pp.oximation, we propose a new method of comparing the mean squared errors(MSE) of the various competing estimators of the true regression parameters ((${\alpha}$ , ${\beta}$). Then we show that a class of estimators including the classical least squares estimator and the maximum likelihood estimator are consistent and first-order efficient within the class of all regular consistent estimators irrespective of type of measurement errors.

• Journal of Power Electronics
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• 제16권1호
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• pp.1-8
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• 2016

Dead time is typically incorporated in voltage source inverter systems to prevent short circuit cases. However, dead time causes an error between the output voltage and reference voltage. Hence, voltage equation-based algorithms, such as motor parameter estimation and back electromotive force (EMF)-based sensorless algorithms, are prone to estimation errors. Several dead-time compensation methods have been developed to reduce output voltage errors. However, voltage errors are still common in zero current crossing areas, and an effect of the error is much worse in a low speed region. Therefore, employing voltage equation-based algorithms in low speed regions is difficult. This study analyzes the conventional dead-time compensation method and output voltage errors in low speed operation areas. A current shaping method that can reduce output voltage errors is also proposed. Experimental results prove that the proposed method reduces voltage errors and improves the accuracy of the parameter estimation method and the performance of the back EMF-based sensorless algorithm.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.323-326
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• 2003

This paper presents a new algorithm that can refine hexahedral elements while maintaining the appropriate connectivity. In the algorithm, at first the regions of mesh to be refined are defined and, then, the zero-thickness element layers inserted into the interfaces between the regions. All the meshes in the regions, in which the zero-thickness layers are inserted, are to be regularized in order to improve the shape of the slender elements on the interfaces. This algorithm is applied to the analysis of plastic deformation process. The results show that the refined mesh gives smaller relative errors than the original mesh.