• Wind and Structures
• /
• v.19 no.3
• /
• pp.321-337
• /
• 2014

This study has developed an Enhanced Remote-Sensing (ERS) scale to improve the accuracy and efficiency of using remote-sensing images of residential building to predict their damage conditions. The new scale, by incorporating multiple damage states observable on remote-sensing imagery, substantially reduces measurement errors and increases the amount of information retained. A ground damage survey was conducted six days after the Joplin EF 5 tornado in 2011. A total of 1,400 one- and two-family residences (FR12) were selected and their damage states were evaluated based on Degree of Damage (DOD) in the Enhanced Fujita (EF) scale. A subsequent remote-sensing survey was performed to rate damages with the ERS scale using high-resolution aerial imagery. Results from Ordinary Least Square regression indicate that ERS-derived damage states could reliably predict the ground level damage with 94% of variance in DOD explained by ERS. The superior performance is mainly because ERS extracts more information. The regression model developed can be used for future rapid assessment of tornado damages. In addition, this study provides strong empirical evidence for the effectiveness of the ERS scale and remote-sensing technology for assessment of damages from tornadoes and other wind events.

• Earthquakes and Structures
• /
• v.3 no.1
• /
• pp.17-35
• /
• 2012

Simplified equations for fundamental period of vibration of skeletal structures provided by most seismic design provisions suffer from the absence of any associated confidence levels and of any reference to their empirical basis. Therefore, such equations may typically give a sector of designers the false impression of yielding a fairly accurate value of the period of vibration. This paper, although not addressing simplified codes equations, introduces a set of mathematical equations utilizing the theory of error propagation and First-Order Second-Moment (FOSM) techniques to determine bounds on the relative error in theoretically calculated fundamental period of vibration of skeletal structures. In a complementary step, and for verification purposes, Monte Carlo simulation technique has been also applied. The latter, despite involving larger computational effort, is expected to provide more precise estimates than FOSM methods. Studies of parametric uncertainties applied to reinforced concrete frame bents - potentially idealized as SDOF systems - are conducted demonstrating the effect of randomness and uncertainty of various relevant properties, shaping both mass and stiffness, on the variance (i.e. relative error) in the estimated period of vibration. Correlation between mass and stiffness parameters - regarded as random variables - is also thoroughly discussed. According to achieved results, a relative error in the period of vibration in the order of 19% for new designs/constructions and of about 25% for existing structures for assessment purposes - and even climbing up to about 36% in some special applications and/or circumstances - is acknowledged when adopting estimates gathered from the literature for relative errors in the relevant random input variables.

• Transactions on Control, Automation and Systems Engineering
• /
• v.1 no.2
• /
• pp.134-140
• /
• 1999

The robust generalized H2 filtering problem for a class of discrete time uncertain linear systems satisfying the sum quadratic constraints(SQCs) is considered. The objective of this paper is to develop robust stability condition using SQCs and design a robust generalized Ha filter to take place of the existing robust Kalman filter. The robust generalized H2 filter is designed based on newly derived robust stability condition. The robust generalized Ha filter bounds the energy to peak gain from the energy bounded exogenous disturbances to the estimation errors under the given positive scalar ${\gamma}$. Unlike the robust Lalman filter, it does not require any spectral assumptions about the exogenous disturbances . Therefore the robust generalized H2 filter can be considered as a deterministic formulation of the robust Kalman filter. Moreover, the variance of the estimation error obtained by the proposed filter is lower than that by the existing robust Kalman filter. The robustness of the robust generalized H2 filter against the uncertainty and the exogenous signal is illustrated by a simple numerical example.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.17 no.1
• /
• pp.64-72
• /
• 2010

Purpose: This study was performed to measure hospital nurses' perceived patient safety culture and their safety care activities, and to investigate the relationship between these two factors. Method: This study was a cross-sectional survey. The participants were 301 nurses working at 4 general hospitals, and data collection was done from June 22 to June 30, 2009 by self-administrated questionnaires. Results: With a possible score of 5 points, the average score for nurses' perceived patient safety culture was 3.34, and for their safety care activities, 4.25. There were perceived differences in patient safety culture and safety care activities according to age, position, length of work experience and number of patient safety education sessions attended. All sub-factors in patient safety culture had a positive relationship with safety care activities. Factors influencing nurses' safety care activities were number of patient safety education sessions attended, hospital environment, and supervisor/manager. These factors explained 58.2% of the variance. Conclusion: The findings indicate that patient safety education is very important to improve nurses' safety care activity. So nursing supervisors/ managers should develop strategies encourage patient safety education, and make nurses' working environment safer.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.1
• /
• pp.33-42
• /
• 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.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.10
• /
• pp.18-22
• /
• 2012

This paper suggests an altitude determination algorithm using GPS and barometric altitude sensors and evaluates the algorithm by digital map contour. A code based GPS altitude has lots of errors so that the car navigation companies can not use this data. Therefore, altitude is calculated by convergence data with GPS and barometric altitude variance in this paper. The modified altitudes are compared with the digital map contour and then this algorithm's effect is evaluated for the car navigation systems.

• Korean Journal of Oriental Medicine
• /
• v.14 no.2
• /
• pp.87-91
• /
• 2008

Background and Purpose: The purpose of this study was investigate statistical validities of previously reported articles that used various statistical techniques such as t-test and analysis of variance. Methods: To analyze the statistical procedures, 66 original articles using those statistical methods were selected from "Korean Journal of Oriental Medicine(KJOM)" published from 1995 to 2007. Results: Twenty-one articles(32%) did not report correct p-values, 33 articles(50%) used mean${\pm}$standard error(mean${\pm}$SE) and 11 articles(l7%) used mean${\pm}$standard deviation(mean${\pm}$SD). Fifty-two articles(95%) of 55 ones which were tested for normal distribution made an error in describing normal distribution. Seventeen articles misused t-test and 12 articles did not carry out the multiple comparison. Conclusions: The training of researchers with clinical statistics or the participation of statisticians in research design will reduce the significant errors in statistical interpretation of the results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.1B
• /
• pp.99-104
• /
• 2000

In this paper, as a digital watermark we propose to use a chaotic sequence instead of the conventional Gaussian sequence. It is relatively easy to generate the chaotic sequence and is very sensitive to the change of initial value. The chaotic sequence adopted in this paper is a modified version of logistic map to give the sequence distribution of Chebyshev map. In the experiments, we applied the Gaussian sequence and chaotic sequence to wavelet coefficients of images to compare the similarity distribution. The results show that, as id the DCT-based watermarking system, the chaotic sequence is robust for various signal processing attacks, Moreover, the similarity variance is smaller than the Gaussian sequence for iterative experiments. It also shows a better performance for compression errors than the Gaussian sequence.

• The Mathematical Education
• /
• v.57 no.1
• /
• pp.55-74
• /
• 2018

The purpose of this study is first to examine the relative influence of each error source and to investigate the optimal measurement conditions to ensure satisfactory multiple reliability coefficients based on the teaching aptitude and personality test for pre-service teachers. Participants were 33 students enrolled in mathematics education in a graduate school of education located in the Seoul metropolitan area from 2013 to 2017. The main results were as follows. First, the estimated variance due to residual was highest, followed by nesting of items within domains, graduate students, interactions of graduate students with domains, and domains. Second, total 96 items, with 12 domains containing 8 items in each domain, with cut score of 598, and original 210 items, with 14 domains containing 15 items in each domain, with cut scores of 615 or 716 were optimal measurement conditions to reach acceptable reliability levels based on the joint consideration of dependability coefficients, cut score dependability coefficients, adjusted dependability coefficients, and standard errors of measurement. Third, larger deviations between the arithmetic mean and the cut score indicated higher reliability coefficients of the test results. Finally, this study suggests ways for practitioners to consider how to apply generalizability theory for criterion-referenced tests and how to develop future research based on limitations.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2001.04a
• /
• pp.102-109
• /
• 2001

In order to take account of the statistical properties of probability variables used in the structural analysis, the conventional approach using the safety factor based on past experience usually estimated the safety of a structure. The real structures could only be analyzed with the error in estimation of loads, material characters and the dimensions of the members. But the errors should be considered systematically in the structural analysis. Structural safety could not precisely be appraised by the traditional structural design concept. Recently, new approach based on the probability concept has been applied to the assessment of structural safety using the reliability concept. Thus, the computer program by the Probabilistic FEM is developed by incorporating the probabilistic concept into the conventional FEM method. This paper estimated for the reliability of a plane stress structure by Advanced First-Order Second Moment method using von Mises, Tresca and Mohr-Coulomb failure criterions. The reliability index and failure probability of attained by the Monte Carlo Simulation method with the von Mises criterion were same as PFEM, but the Monte Carlo Simulation were very time-consuming. The variance of member thickness and load could influence the reliability and failure probability most sensitively among the design variables from the results of the parameter analysis. And proper failure criterion must be used to design safely.