• The Journal of Information Systems
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• v.14 no.3
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• pp.117-122
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• 2005

This paper presents a method for detecting scene changes in video sequences, in which the $chi^{2}$-test is modified by imposing weights according to NTSC standard. To automatically determine threshold values for scene change detection, the proposed method utilizes the frame differences that are obtained by the weighted $chi^{2}$-test. In the first step, the mean and the standard deviation of the difference values are calculated, and then, we subtract the mean difference value from each difference value. In the next step, the same process is performed on the remained difference values, mean-subtracted frame differences, until the stopping criterion is satisfied. Finally, the threshold value for scene change detection is determined by the proposed automatic threshold estimation algorithm. The proposed method is tested on various video sources and, in the experimental results, it is shown that the proposed method is reliably estimates the thresholds and detects scene changes.

• The KIPS Transactions:PartC
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• v.15C no.1
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• pp.31-36
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• 2008

The clock frequency difference of sensor nodes is one of main parameters in TOF estimation and affect to degrade ranging algorithms to estimate positions of mobile nodes in wireless sensor networks. The specification of IEEE802.15.4a describes asynchronous TWR and SDS-TWR insensitive to frequency difference without any additional network synchronization. But the TWR and SDS-TWR can not eliminate sufficiently the effect of frequency difference of node pair, packet processing delay and its difference. Especially use of low cost oscillator with wide range offset, sensor node with different hardware and software can make the positioning errors worse. We propose an estimation method of frequency differences, and apply the measured frequency differences to TWR and SDS-TWR. We evaluate the performance of the proposed algorithm with simulation, and make certain that the proposed method enhances the performance of existing algorithms with positioning errors less than 25 cm.

• The Korean Journal of Applied Statistics
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• v.25 no.6
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• pp.877-887
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• 2012

The Bank of Korea changed its method of GDP estimation from a fixed-weighted to a chain-weighted measure in 2009. The fixed-weighted method had had problems such as substitution bias and the rewriting of economic history. As a result of the change, annual growth rates calculated using the chain-weighted method from 1970 through 2008 turned out to be 0.8%p higher on average than the existing rates. The quarterly average chain-weighted growth rates were 0.19%p higher than the fixed-weighted ones, but they changed in the same directions. In this paper we analyze whether the differences in rates between the two calculation methods would bring about a difference in the cyclical characteristics of GDP. We conclude that although there were differences in growth rates after introduction of the chain-weighted method, there was no difference in the cyclical fluctuation.

• Journal of the Ergonomics Society of Korea
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• v.14 no.1
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• pp.1-7
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• 1995

In this paper, the effectiveness and accuracy of using the direct estimation method were investigated in determining a worker's lifting capacity or the maximum acceptable weight of lifting (MAWOL) of symmetrical fifting tasks in the workplace were investigated. Six lifting tasks involving two vertical fifting start-end points (0-80cm, 47-102cm) and three lifting frequencies (1, 2, and 4 lifts/minute) were studied. Ten young, male subjects performed the six lifting tasks to predict the MAWOL using the psychophysical method and the direct estimation method. The main results indicated that there were no significant differences between the MAWOLs determined by the two methods except for the lifting frequency of 4 lifts/minute. Analysis of variance was performed on the task rating data to check the consistency of the task rating across subjects, which revealed no significant difference.

• International Journal of Computer Science & Network Security
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• v.21 no.7
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• pp.93-102
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• 2021

This study aimed to test method on the accuracy of estimating the items parameters and ability, using the Three Parameter Logistic. To achieve the objectives of the study, an achievement test in chemistry was constructed for third-year secondary school students in the course of "natural sciences". A descriptive approach was employed to conduct the study. The test was applied to a sample of (507) students of the third year of secondary school in the "Natural Sciences Course". The study's results revealed that the (EAP) method showed a higher degree of accuracy in the estimation of the difficulty parameter and the abilities of persons higher than the MML method. There were no statistically significant differences in the accuracy of the parameter estimation of discrimination and guessing regarding the difference of the two methods: (MML) and (EAP).

• Journal of the Ergonomics Society of Korea
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• v.30 no.4
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• pp.535-540
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• 2011

Objective: The aim of this paper is to survey the gender differences Work-related musculoskeletal disorders among agriculture workers. Background: The number of occupational injuries has been decreasing trend in Korea, but it has been increasing in agriculture. The ratio of women worker shows steady increasing trend among the agricultural worker in Korea. Method: This study investigated through the questionnaire to 358 agricultural workers who are working for agriculture located in Gyeongnam, Gyeongbuk and Jeju. Results: The task types occurring frequently and the weight of a heavy object handled according to the sex were showed statistically significant difference. The estimation of WMSDs patients by sex appeared statistically very significant difference. Conclusion: The prevalence rate of WMSDs in female was about 21 percent higher than the prevalence rate of WMSDs in male. Application: The result of this study will help improvement of work environment and prevention of WMSDs in agricultural work.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.284-290
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• 2012

This paper addresses a new passive target tracking problem using the range differences measured by cooperative UAVs. In order to solve the range difference based passive target tracking problem within the framework of linear robust state estimation, the uncertain linear measurement model which contains the stochastic parameter uncertainty is derived by using the noisy range difference measurements. To cope with the performance degradation due to the stochastic parameter uncertainty, the recently developed non-conservative robust Kalman filtering technique [1] is applied. For the cruciform formation flying UAVs, the relationship between the target tracking performance and the measurement errors is quantitatively analyzed. The proposed filter has practical advantages over the classical nonlinear filters because, for its recursive linear structure, it can provide satisfactory convergence properties and is suitable for real-time multiple UAVs applications. Through the simulations, the usefulness of the proposed method is demonstrated.

• Journal of Korean Physical Therapy Science
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• v.18 no.4
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• pp.73-79
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• 2011

Purpose : This study is to know how position change in high-heels affects sacral tilt angle. 15 healthy women aged 21.87(standard deviation=3.54) were tested. Method : Lumbar and sacral tilt angle was measured by radiography barefooted, and after 15 mins of application time, they were measured in the same way in high-heels. Result : There was not notable difference in lumbar lordosis, lumbosacral angle, and sacral tilt angle. However, there was differences in change degree, which was measured by estimation data of [post-pre)/pre]${\times}$100. Conclusion : There was no notable difference in lumbar lordosis, lumbosacral angle, and sacral tilt angle, but as there were differences in change degree, research about how women's lumbar change when heel height increases is needed.

• Environmental and Resource Economics Review
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• v.19 no.4
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• pp.875-896
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• 2010

Using the difference in differences (DID) estimation method, this paper analyzes the effect of European Union's Emission Trading Scheme (EU ETS) on the reduction of per capita $CO_2$ emission among the twenty five participating countries. For this, the panel dataset of forty two European countries for the period 1990~2007 is constructed. Special attention is paid to the bias of the standard errors in the DID estimation due to the presence of serial correlation in the error terms. The results shows quite a robust effect of EU ETS on the reduction of per capita $CO_2$ emission among the participating countries regardless of the calculation methods of standard errors. The results also shows that the increased implicit tax rate on energy has a robust effect on the reduction of per capita $CO_2$ emission. On the contrary, the estimation results regarding the effects of per capita GDP and population density on the per capita $CO_2$ emission seem inconsistent. In particular, the environmental Kuznets curve is not statistically supported with the use of robust standard errors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1887-1893
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• 2016

The VSA(Video Signal Analysis) method is the time-domain approach for estimating ultrasonic attenuation which utilizes the envelop signals from backscattered rf signals. The echogenicity of backscattered ultrasonic signals, however, from deeper depths are distorted when the broadband transmit pulse is used and it degrades the estimation accuracy of attenuation coefficients. We propose the modified VSA method using adaptive bandpass filters according to the centroid shift of echo signals as a pulse propagates. The technique of dual-reference diffraction compensation is also proposed to minimize the estimation errors because the difference of attenuation properties between the reference and sample aggravates the estimation accuracy when the differences are accumulated in deeper depth. The proposed techniques minimize the distortion of relative echogenicity and maximize the signal-to-noise ratio at the given depth. Simulation results for numerical tissue-mimicking phantoms show that the Rectangular-shaped filter with the appropriate center frequency exhibits the best estimation performance and the technique of the dual-reference diffraction compensation dramatically improves accuracy for the region after the beam focus.