• 영어어문교육
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• 제10권3호
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• pp.159-175
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• 2004

This paper investigated the types of errors on English pronunciation and intelligibility of Korean EFL students, and the relationship between the pronunciation accuracy and intelligibility. Thirty one students were evaluated by six English native speakers in terms of overall intelligibility and accuracy In five areas such as nuclear stress, word stress, syllable structure, consonants and vowels. According to the findings of the study, pronunciation errors were made by the subjects more frequently In word stress than any other area of pronunciation accuracy. The Pearson correlation analysis showed that intelligibility was related with word stress, syllable structure, consonants and vowels, and the stepwise multiple regression analysis indicated that, among the above five areas of pronunciation accuracy, word stress best accounted for the intelligibility of a given sentence. In the conclusion, the importance of teaching pronunciation of in those five areas with a special focus on word stress was emphasized m terms of intelligibility.

• Applied Microscopy
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• 제41권1호
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• pp.75-79
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• 2011

For quantitative analysis of nano-crystal structure, we reported the accuracy improvement method of lattice parameters measured from electron diffraction. For calculation of Au lattice parameters used as a standard crystal structure, it was considered two different acquisition methods (detector and enegy-filter) and three different calculation methods (conventional, least-square and regression fit). As a result, the measurement reliability could be enhanced by using CCD camera which gives higher performance, while energy-filtering did not affect the improvement the camera constant accuracy. Also, the accuracy of lattice parameters could be improved up to $10^{-4}$ order by regression fitting with correction formula. Finally, it is expected that the combination of regression fitting and intensity extraction from energy-filtered precession electron diffraction gives a solution of quantitative structure analysis for unknown nano-crystals.

• 한국정밀공학회지
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• 제16권3호통권96호
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• pp.215-221
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• 1999

The object of the thermal error compensation system in machine tools is improving the accuracy of a machine tool through real time error compensation. The accuracy of the machine tool totally depends on the accuracy of thermal error model. A thermal error model can be obtained by appropriate combination of temperature variables. The proposed method for optimal variable selection in the thermal error model is based on correlation grouping and successive regression analysis. Collinearity matter is improved with the correlation grouping and the judgment function which minimizes residual mean square is used. The linear model is more robust against measurement noises than an engineering judgement model that includes the higher order terms of variables. The proposed method is more effective for the applications in real time error compensation because of the reduction in computational time, sufficient model accuracy, and the robustness.

• 한국측량학회지
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• 제20권3호
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• pp.235-242
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• 2002

고해상도의 IKONOS 위성 영상데이터로부터 도로 정보를 판독.추출하고 그 정확도를 분석하고자 하였다. RFM을 이용하여 기하보정영상을 생성한 후, 이 영상으로부터 도로를 판독하고 스크린디지타이징 하였다. 도로 판독 및 추출 정확도를 평가하기 위하여 도로 경계선의 위치와 도로 폭을 수치지도와 비교한 결과, 도로 경계선은 $\pm$3.4m, 도로의 폭은 $\pm$1.1m의 정확도로 추출되었다.

• 한국산학기술학회논문지
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• 제19권12호
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• pp.863-871
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• 2018

본 논문에서는 기존의 취약점 분석 도구들의 미탐지, 오탐지, 과탐지를 발생시켜 정확한 취약점 탐지를 어렵게 하는 문제점을 해결하고 분석 대상이 되는 어플리케이션의 위험도를 평가하여 안전한 어플리케이션을 개발하거나 관리할 수 있는 정적 및 동적 분석을 이용한 크로스 체크기반의 취약점 탐지 기법을 제안한다. 또한 각각의 취약점이 가지고 있는 자체 위험도를 계산하고 정확도를 높인 취약점 탐지 기법을 바탕으로 최종적인 어플리케이션의 위험도를 평가, 제시함으로서 안전한 어플리케이션의 개발 및 운영을 돕는다. 제안하는 기법은 정적 분석 및 동적 분석 기법을 사용하는 도구들의 상호작용을 통해 각 기법의 단점들을 극복하여 취약점 탐지 정확도를 향상시킨다. 또한 기존의 취약점 위험도평가 시스템은 취약점 자체 위험도에 대해서만 평가하였으나, 제안하는 위험도 평가는 취약점 자체 위험도와 탐지 정확도를 복합적으로 반영하여 어플리케이션이 얼마나 위험에 노출되어 있는지를 평가한다. 제안하는 기법은 CWE에서 SANS top 25의 상위 10위 항목을 기준으로 기존의 분석 도구들과 탐지 가능한 목록, 탐지 정확도를 비교분석하였으며, 기존의 취약점 위험도에 대한 정량적 평가 시스템과 제안하는 어플리케이션 위험도 평가 결과를 비교 분석 및 평가하였다. 제안하는 기법으로 프로토타입 분석 툴을 구현하여 실험을 통해 어플리케이션의 취약점을 분석하였을 때, 기존의 분석 도구들의 취약점 탐지 능력보다 우수한 것으로 나타났다.

• 한국도로학회논문집
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• 제18권1호
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• pp.73-83
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• 2016

PURPOSES : The purpose of this study is to develop a method for improving the accuracy of analysis results obtained from a two-dimensional (2-D) numerical analysis model of continuously reinforced concrete pavement (CRCP). METHODS : The analysis results from the 2-D numerical model of CRCP are compared with those from more rigorous three-dimensional (3-D) models of CRCP, and the relationships between the results are recognized. In addition, the numerical analysis results are compared with the results obtained from field experiments. By performing these comparisons, the calibration factors used for the 2-D CRCP model are determined. RESULTS : The results from the comparisons between 2-D and 3-D CRCP analyses show that with the 2-D CRCP model, concrete stresses can be overestimated significantly, and crack widths can either be underestimated or overestimated by a slight margin depending on the assumption of plane stress or plane strain. The behaviors of crack width in field measurements are comparable to those obtained from the numerical model of CRCP. CONCLUSIONS : The accuracy of analysis results from the 2-D CRCP model can be improved significantly by applying calibration factors obtained from comparisons with 3-D analyses and field experiments.

• 대한의용생체공학회:의공학회지
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• 제41권3호
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• pp.121-127
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• 2020

The purpose of this paper is to review the validation on the application of low frequency IMU(Inertial Measurement Unit) sensors by replacing high frequency motion analysis systems. Using an infrared-based 3D motion analysis system and IMU sensors (22 Hz) simultaneously, the gait cycle and knee flexion angle were measured. And the accuracy of each gait parameter was compared according to the statistical analysis method. The Bland-Altman plot analysis method was used to verify whether proper accuracy can be obtained when extracting gait parameters with low frequency sensors. As a result of the study, the use of the new gait assessment system was able to identify adequate accuracy in the measurement of cadence and stance phase. In addition, if the number of gait cycles is increased and the results of body anthropometric measurements are reflected in the gait analysis algorithm, is expected to improve accuracy in step length, walking speed, and range of motion measurements. The suggested gait assessment system is expected to make gait analysis more convenient. Furthermore, it will provide patients more accurate assessment and customized rehabilitation program through the quantitative data driven results.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2007년도 춘계학술발표회 논문집
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• pp.447-450
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• 2007

Positioning technology for moving object is an important and essential component of ubiquitous. Also RFID(Radio Frequency IDentification) is a core technology of ubiquitous wireless communication. In this study we adapted kalman-filter theory to RFID-based Positioning System in order to trace a time-variant moving object and verify the positioning accuracy using RMSE (Roong technology for moving object is an important and essential component of ubiquitous Mean Square Error). The purpose of this study is to verify an effect of kalman-filter on the positioning accuracy and to analyze what does each design factor have an effect on the positioning accuracy by means of simulations and to suggest a standard of optimal design factor of a RFID-based Positioning System. From the results of simulations, Kalman-filer improved the positioning accuracy remarkably; the detection range of RFID tag is not a determining factor. The smaller standard deviation of detection range improves the positioning accuracy. However it accompanies a smaller fluctuation of the positioning accuracy. The larger detection rate of RFID tag yields the smaller fluctuation in the positioning accuracy and has more stable system and improves the positioning accuracy;

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.337-340
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• 2008

The cross section shape of intermediate die is one of important parameters to obtain dimensional accuracy of final product in shaped drawing process. Until now it has been designed by the experience or trial and error of the expert. In this study, the cross section shape of intermediate die fur spline shape is determined by the electronic field analysis, shape factor method. The result of the electronic field analysis, shape factor method has been compared with that of the present method. The effects of cross section shape on the dimensional accuracy were investigated by using FE analysis. And then the multi-stage shaped drawing experiments were performed to verify the results of FE analysis. As a result, the cross section shape from the electronic field analysis had the good dimensional accuracy. The electronic field analysis can be used for the method to obtain the cross section shape of intermediate die in shaped drawing process.

• Structural Engineering and Mechanics
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• 제75권6호
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• pp.771-784
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• 2020

Reliability analysis techniques combining with various surrogate models have attracted increasing attention because of their accuracy and great efficiency. However, they primarily focus on the structures with continuous response, while very rare researches on the reliability analysis for structures with discontinuous response are carried out. Furthermore, existing adaptive reliability analysis methods based on importance sampling (IS) still have some intractable defects when dealing with small failure probability, and there is no related research on reliability analysis for structures involving discontinuous response and small failure probability. Therefore, this paper proposes a novel reliability analysis method called AGPC-IS for such structures, which combines adaptive Gaussian process classification (GPC) and adaptive-kernel-density-estimation-based IS. In AGPC-IS, an efficient adaptive strategy for design of experiments (DoE), taking into consideration the classification uncertainty, the sampling uniformity and the regional classification accuracy improvement, is developed with the purpose of improving the accuracy of Gaussian process classifier. The adaptive kernel density estimation is introduced for constructing the quasi-optimal density function of IS. In addition, a novel and more precise stopping criterion is also developed from the perspective of the stability of failure probability estimation. The efficiency, superiority and practicability of AGPC-IS are verified by three examples.