• The Journal of Korean Association of Computer Education
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• v.8 no.6
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• pp.103-111
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• 2005

This paper presents a novel automated threshold-decision algorithm that uses the mean and standard-deviation values obtained from the difference values of consecutive frames. At first, the calculation of difference values is obtained by the weighted ${\chi}^2$-test algorithm which was modified by joining color histogram to ${\chi}^2$-test algorithm. The weighted ${\chi}^2$-test algorithm can subdivide the difference values by imposing weights according to NTSC standard. In the first step, the proposed automatic threshold-decision algorithm calculates the mean and standard-deviation value from the total difference values, and then subtracts the mean value from the each difference values. In the next step, the same process is performed on the remained difference values, and lastly, the threshold is detected from the mean when the standard deviation has a maximum value. The proposed method is tested on various video sources and, in the experimental results, it is shown that the proposed method efficiently estimates the thresholds and reliably detects scene changes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1482-1489
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• 2007

In this paper, characteristics of infrasound and low-frequency noise emission from large modern wind turbines are experimentally investigated. The sound measurement procedures of IEC 61400-11 and ISO 7196 are utilized to field test and evaluation of noise emission from each of 1.5 MW and 660 kW wind turbines using the stall regulation and the pitch control for the power regulation, respectively. It was found that the G-weighted SPLs of low-frequency noise including infrasound shows positive correlation with the wind speeds, irrespective of methods of power regulation. This highlights the potential complaint of local community against the infrasound and low-frequency noise of wind turbines. The comparison of measured data with the existing hearing thresholds and criteria curves shows that it is highly probable that the low-frequency noise from the 1.5 MW and 660 kW wind turbines in the frequency range over 30 Hz leads to the psychological complaint of ordinary adults, and that the infrasound in the frequency range from 5 Hz to 8 Hz causes the complaint by rattling the house fitting such as doors and windows.

• Korean Management Science Review
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• v.32 no.4
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• pp.97-108
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• 2015

This study proposes a mathematical model to estimate the economic value of weather forecast service, among which the precipitation forecast service is focused. The value is calculated in terms of users' satisfaction or dissatisfaction resulted from the users' decisions made by using the precipitation probabilistic forecasts and thresholds. The satisfaction values can be quantified by the traditional value score model, which shows the scaled utility values relative to the perfect forecast information. This paper extends the value score concept to a collective value score model which is defined as a weighted sum of users' satisfaction based on threshold distribution in a group of the users. The proposed collective value score model is applied to the picnic scenario by using four hypothetical sets of probabilistic forecasts, i.e., under-confident, over-confident, under-forecast and over-forecast. The application results show that under-confident type of forecasts outperforms the others as a measure of the maximum collective value regardless of users' dissatisfaction patterns caused by two types of forecast errors, e.g., miss and false alarm.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.445-454
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• 2020

Structural damage identification (SDI) is a crucial step in structural health monitoring. However, some of the existing SDI methods cannot provide enough identification accuracy and efficiency in practice. A novel whale optimization algorithm (WOA) based method is proposed for SDI by weighting modal data and flexibility assurance criterion in this study. At first, the SDI problem is mathematically converted into a constrained optimization problem. Unlike traditional objective function defined using frequencies and mode shapes, a new objective function on the SDI problem is formulated by weighting both modal data and flexibility assurance criterion. Then, the WOA method, due to its good performance of fast convergence and global searching ability, is adopted to provide an accurate solution to the SDI problem, different predator mechanisms are formulated and their probability thresholds are selected. Finally, the performance of the proposed method is assessed by numerical simulations on a simply-supported beam and a 31-bar truss structures. For the given multiple structural damage conditions under environmental noises, the WOA-based SDI method can effectively locate structural damages and accurately estimate severities of damages. Compared with other optimization methods, such as particle swarm optimization and dragonfly algorithm, the proposed WOA-based method outperforms in accuracy and efficiency, which can provide a more effective and potential tool for the SDI problem.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.235-245
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• 1998

Adquate friction resistance is needed to prevent pavement slipperiness and to allow vehicles to stop in a reasonable distance. Performance of the aggregates is reduced over time by wear and polishing as a consequence of vehicular traffic. In this research, the objective was to develop a laboratory method to test Indiana gravel aggregates to predict field performance, and determine causes for the range of values amang gravel aggregates. The assessment of gravel sources was primarily on the basis of individual rock types and those proportions comprising the gravel. Polish and friction values were determined in the laboratory with the British Wheel and Pendulum. The gravels of this study were composed primarily of carbonate aggregates that showed considerable variability in polishing thresholds. Igneous and metamorphic constituents polished to a lesser degree and are expected to improve overall aggregate performance. Estimates of the IFV (Initial Friction Value) and PV (Polished Value) for crushed gravel samples can be made based on the percentage of rock types present in the sample. A weighted average is used to make this calculation.

• Journal of Audiology & Otology
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• v.23 no.2
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• pp.63-68
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• 2019

Background and Objectives: To investigate the relationship between hearing impairment and alcohol drinking patterns in South Korean adults. Subjects and Methods: Data collection was performed by Korean National Health and Nutrition Survey from January 1 to December 31, 2012. Data analyses were performed from February 20 to March 3, 2018. Data from 3,860 adults 20 years of age or older without a history of malignancy or chronic otitis media in the Korean National Health and Nutrition Survey 2012 database who participated in the health questionnaires, and who had available results from otologic examinations that included pure tone audiogram, were included. Pure-tone average hearing thresholds were calculated at 500, 1,000, 2,000, and 4,000 Hz. Hearing loss was defined as a pure-tone average >40 dB in one or both ears. The Alcohol Use Disorder Identification Test was used to evaluate drinking statuses of subjects. Data were analyzed using the complex-sample χ²-test of independence and a complex-sample logistic regression analysis. Results: Of the 29,954,319 individuals in the weighted cross-sectional study population, 15,106,040 (50.4%) were men and 14,848,098 (49.6%) were women. A total of 8.1% of men and 7% of women had hearing impairment. The degrees of drinking with appropriate, risky, and hazardous drinking habits were 58.2, 32.1, and 9.7% among men; and 76.4, 12.5, and 11.1% among women, respectively. Among men, the odds ratio of hearing loss increased by 2.506 times when comparing hazardous and appropriate drinking (confidence interval, 1.083 to 5.800, p=0.002). Moderate alcohol consumption (≤2 drinks per day) was not protective for hearing in either group. Conclusions: As hazardous drinking tends to coexist with hearing impairment in men, appropriate prevention and intervention strategies should be emphasized. A longitudinal study to investigate harmful drinking and the mechanism of hearing loss should be performed.

• Korean Journal of Audiology
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• v.23 no.2
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• pp.63-68
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• 2019

Background and Objectives: To investigate the relationship between hearing impairment and alcohol drinking patterns in South Korean adults. Subjects and Methods: Data collection was performed by Korean National Health and Nutrition Survey from January 1 to December 31, 2012. Data analyses were performed from February 20 to March 3, 2018. Data from 3,860 adults 20 years of age or older without a history of malignancy or chronic otitis media in the Korean National Health and Nutrition Survey 2012 database who participated in the health questionnaires, and who had available results from otologic examinations that included pure tone audiogram, were included. Pure-tone average hearing thresholds were calculated at 500, 1,000, 2,000, and 4,000 Hz. Hearing loss was defined as a pure-tone average >40 dB in one or both ears. The Alcohol Use Disorder Identification Test was used to evaluate drinking statuses of subjects. Data were analyzed using the complex-sample χ²-test of independence and a complex-sample logistic regression analysis. Results: Of the 29,954,319 individuals in the weighted cross-sectional study population, 15,106,040 (50.4%) were men and 14,848,098 (49.6%) were women. A total of 8.1% of men and 7% of women had hearing impairment. The degrees of drinking with appropriate, risky, and hazardous drinking habits were 58.2, 32.1, and 9.7% among men; and 76.4, 12.5, and 11.1% among women, respectively. Among men, the odds ratio of hearing loss increased by 2.506 times when comparing hazardous and appropriate drinking (confidence interval, 1.083 to 5.800, p=0.002). Moderate alcohol consumption (≤2 drinks per day) was not protective for hearing in either group. Conclusions: As hazardous drinking tends to coexist with hearing impairment in men, appropriate prevention and intervention strategies should be emphasized. A longitudinal study to investigate harmful drinking and the mechanism of hearing loss should be performed.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.4
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• pp.359-367
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• 2023

In order to ensure the high-integrity of reference stations of satellite navigation system, cycle slip should be precisely monitored and compensated. In this paper, we proposed a cycle slip algorithm for the integrity monitoring of the reference stations. Unlike the legacy method using the Melbourne-Wübbena (MW) combination and ionosphere combination, the proposed algorithm is based on ionosphere combination only, which uses high precision carrier phase observations without pseudorange observations. Two independent and complementary ionosphere combinations, Ionospheric Negative (IN) and Ionospheric Positive (IP), were adopted to avoid insensitive cycle slip pairs. In addition, a second-order time difference was applied to the IN and IP combinations to minimize the influence of ionospheric and tropospheric delay even under severe atmosphere conditions. Then, the cycle slip was detected by the thresholds determined based on error propagation rules, and the cycle slip was identified through weighted least square method. The performance of the proposed cycle slip algorithm was validated with the 1 Hz dual-frequency carrier phase data collected under the difference levels of ionospheric activities. For this experiment, 15 insensitive cycle slip pairs were intentionally inserted into the raw carrier phase observations, which is difficult to be detected with the traditional cycle slip approach. The results indicate that the proposed approach can successfully detect and compensate all of the inserted cycle slip pairs regardless of ionospheric activity. As a consequence, the proposed cycle slip algorithm is confirmed to be suitable for the reference station where real time high-integrity monitoring is crucial.

• Journal of Preventive Medicine and Public Health
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• v.28 no.4 s.51
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• pp.899-910
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• 1995

This study was conducted to determine the correlation between weighted needle pinprick sensory threshold(PPT) and sensory nerve conduction tests. The subjects were 53 healthy controls, 31 diabetic patients without peripheral neuropathic symptoms(DM) and 36 diabetic patients with peripheral neuropathic symptoms(DN). PPT was measured on the index and little fingers, bilaterally, as well as under the lateral malleolus, bilaterally. In electrophysiologic assessment the left and right median, ulnar and sural nerves were studied. Each mean PPTs was high in order of controls, DM and DN. Age adjusted PPT was significantly different among three groups on right little finger(p<0.05) and left malleolus(p<0.05), but not significantly different between DN and DM on other sites. Each sensory nerve conduction velocity and amplitude was statistically significantly different among three groups(p<0.05). Correlations of PPT with sensory nerve conduction velocity and amplitude were statistically significant on each site and ranged from -0.4203(left malleolus) to -0.5649(right index finger) and from -0.3897(left index finger) to -0.6200(right index finger), respectively. When electrophysiological study is not feasible, measurement of PPT may be helpful for the assessment of peripheral sensory neurological function.

• Journal of Korean Physical Therapy Science
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• v.3 no.1
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• pp.929-941
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• 1996

This study was conducted to determine the association between weighted needle pinprick sensory threshold(PPT) and sensory nerve conduction studies. The subjects were 53 healthy controls, 31 diabetic patients without peripheral neuropathic symptoms(DM) and 36 diabetic patients with peripheral neuropathic symptoms(DN). PPT was measured on the index and little fingers, bilaterally, as well as under the lateral malleolus, bilaterally. In electrophysiologic assessment the left and right median, ulnar and sural nerves were studied. Mean PPT in DN, DM and controls was high in turn on each sites tested. Age controlled PPT was significantly different among three groups on right little finger(p<0.05) and left malleolus(p<0.05), but on other sites, not statistically significantly different between DN and DM. The results were as follows: Sensory nerve conduction velocity and amplitude on each nerve tested were statistically significantly different among three groups(p<0.05). Correlation of PPT with sensory nerve conduction velocity and amplitude were statistically significant on each site and ranged from -0.4203(left malleolus) to -0.5649(right index finger) and from -0.3897(left index finger) to -0.6200(right index finger), respectively. When electrophysiological study is not feasible, measurement of PPT may be helpful for the assessment of peripheral sensory neurological function.