• Korean Journal of Remote Sensing
• /
• v.39 no.3
• /
• pp.257-268
• /
• 2023

Sea ice plays an important role in Earth's climate by regulating the amount of solar energy absorbed and controlling the exchange of heat and material across the air-sea interface. Its growth, drift, and melting are monitored on a regular basis by satellite observations. However, low-resolution products with passive microwave radiometer have reduced accuracy during summer to autumn when the ice surface changes rapidly. Synthetic aperture radar (SAR) observations are emerging as a powerful complementary, but previous researches have mainly focused on winter ice. In this study, sea ice drift tracking was evaluated and analyzed using SAR images and tracker with global positioning system (GPS) during late summer-early autumn period when ice surface condition changes a lot. The results showed that observational uncertainty increases compared to winter period, however, the correlation coefficient with GPS measurements was excellent at 0.98, and the performance of the ice tracking algorithm was proportional to the sea ice concentration with a correlation coefficient of 0.59 for ice concentrations above 50%.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.5D
• /
• pp.453-459
• /
• 2010

In the study of traffic safety, it is utmost important to obtain more reliable estimates of the expected crashes for a site (or a segment). The observed crashes have been mainly used as the estimate of the expected crashes in Korea, while the empirical Bayes (EB) estimates based on the Poisson-gamma mixture model have been used in the USA and several European countries. Although numerous studies have used the EB method for estimating the expected crashes and/or the effectiveness of the safety countermeasures, no past studies examine the difference in the estimation errors between the two estimates. Thus, this study compares the estimation errors of the two estimates using a Monte Carlo simulation study. By analyzing the crash dataset at 3,000,000 simulated sites, this study reveals that the estimation errors of the EB estimates are always less than those of the observed crashes. Hence, it is imperative to incorporate the EB method into the traffic safety research guideline in Korea. However, the results show that the differences in the estimation errors between the two estimates decrease as the uncertainty of the prior distribution increases. Consequently, it is recommended that the EB method be used with reliable hyper-parameter estimates after conducting a comprehensive examination on the estimated negative binomial model.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6D
• /
• pp.859-869
• /
• 2008

These days, almost every industry's production line has become automatic and this phenomenon brought a lot of benefits such as increase in productivity and economical effect, assurance in industrial safety, better quality and compatibility. However, unlike industrial production line, in construction industry, automation has number of barriers like uncertainty incidents and intellectual judgment to make ability to make solution out of it. Therefore construction industry is still demanding use of construction machine through labor. Due to this matter operational labor in construction industry is aging and fading. To solve these problem, in developed nations like Europe, US or Japan are keep researching for the automation in construction and road pavement, strengthening and some other simple operations have been worked through automation but in civil engineering site, automation research is still low despite of its importance in constructional site. For automating civil engineering operation, effective operational plan have to be set by analyzing ground information acquainted. If skillful worker apply heuristics, trial & error can be reduced with increased safety and the effective work plan can be established. Hence, this research will introduce Intellectual Task Planning System for Intelligent Excavating System's effective work plan and heuristics applied in each steps.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.10a
• /
• pp.128-130
• /
• 2021

This study aims to implement a Regression Analysis system for predicting the appropriate production of flatfish. Due to Korea's signing of FTAs with countries around the world and accelerating market opening, Korean flatfish farming businesses are experiencing many difficulties due to the specificity and uncertainty of the environment. In addition, there is a need for a solution to problems such as sluggish consumption and price drop due to the recent surge in imported seafood such as salmon and yellowtail and changes in people's dietary habits. in this study, Using the python module, xlwings, it was used to obtain for the production amount of flatfish and to predict the amount of flatfish to be produced later. was used to predict the amount of flatfish to be produced in the future. Therefore, based on the analysis results of this prediction of flatfish production, the flatfish aquaculture industry will be able to come up with a plan to achieve an appropriate production volume and control supply and demand, which will reduce unnecessary economic loss and promote new value creation based on data. In addition, through the data approach attempted in this study, various analysis techniques such as artificial neural networks and multiple regression analysis can be used in future research in various fields, which will become the foundation of basic data that can effectively analyze and utilize big data in various industries.

• Analytical Science and Technology
• /
• v.19 no.5
• /
• pp.400-406
• /
• 2006

Hydrogen analysis by elastic recoil detection has been performed utilizing polyimide film as a reference sample of known hydrogen content assuming the soundness of ion beam current integration. However beam current integration at higher incidence angle is not reliable. Scattering yield per unit fluence by current integration which is normalized per unit path length decreases as the sample tilt angle is getting higher. Moreover because beam current integration at high tilt angle is incomplete, hydrogen evaluation is very risky by direct comparison of sequentially collected recoil spectra between reference and target sample. In this study, primary ion beam dose is determined by backscattering spectrum that is collected simultaneously with recoil spectrum instead of ion beam current integration in order to reduce uncertainty arising in the process of current integration and to enhance the reliability of quantitative analysis. Three test samples are selected $-7.6{\mu}m$ polyimide film, hydrogen implanted silicondioxide and Au deposited carbon wafer- and analyzed by two methods and compared.

• Analytical Science and Technology
• /
• v.19 no.1
• /
• pp.1-8
• /
• 2006

The isotope dilution method was used for the determination of Br impurity in $1000{\mu}g/g$ Cl standard solution. Since relatively pure KCl salt was used for the preparation of the Cl standard solution, the Br impurity determination suffers from both spectral and non-spectral interferences due to the presence of a large amount of K and Cl matrices. AG2-X8 anion-exchange resin was employed to separate the Br analyte from the matrices, and RF power was raised to 1500 W and nebulizer gas flow rate was lowered to 0.77 L/min to reduce background from the $ArArH^+$ molecular ions. The Br impurity in the $1000{\mu}g/g$ Cl standard solution was determined to be 43.7 ng/g with the standard addition method. The analytical result was in good agreement with 41.2 ng/g (RSD 1.6%) determined by the isotope dilution method to lower uncertainty from poor reproducibility of the anion-exchange process.

• Analytical Science and Technology
• /
• v.21 no.4
• /
• pp.316-325
• /
• 2008

An inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with flow injection-hydride generation system was used for the determination of trace arsenic in seawater sample. The accuracy in this method was verified by the analysis of certified reference materials (CRM) of seawater (CASS-4, NASS-5). The analytical results agreed with certified value within the range of uncertainty. The expanded uncertainties for CASS-4 and NASS-5 in this experiment were ranged from 6.2% to 6.8% obtained from repeated analyses of the CRMs (n=5). The detection limit of $As^+$ (m/z=74.9216) in this method was confirmed about 0.01 ug/kg. Linearity obtained from calibration curve of arsenic was excellent ($R^2=1$). The detection at $As^+$ (m/z=74.9216) and $AsO^+$ (m/z=90.9165) by using oxygen reaction gas in DRC mode was compared. Sensitivity at $AsO^+$ (m/z=90.9165) was decreased about 25-fold, but the analytical results are the same that at $As^+$ (m/z=74.9216).

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.6B
• /
• pp.599-606
• /
• 2010

Due to the short period of precipitation data in Korea, the uncertainty of drought analysis is inevitable from a point frequency analysis. So it is desired to introduce a regional drought frequency analysis. This study first extracted drought characteristics from 3-month and 12-month moving average rainfalls which represent short and long-term droughts, respectively. Then, the homogeneous regions were distinguished by performing a principal component analysis and cluster analysis. The Korean peninsula was classified into five regions based on drought characteristics. Finally, this study applied the bivariate frequency analysis using a kernel density function to quantify the regionalized drought characteristics. Based on the bivariate drought frequency curves, the drought severities of five regions were evaluated for durations of 2, 5, 10, and 20 months, and return periods of 5, 10, 20, 50, and 100 years. As a result, the largest severity of drought was occurred in the Lower Geum River basin, in the Youngsan River basin, and over in the southern coast of Korea.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6A
• /
• pp.765-778
• /
• 2008

Performance Profiles are essential to predict the performance variation over time for the bridge management system (BMS) based on risk management. In general, condition profiles based on experts opinion and/or visual inspection records have been used widely because obtaining profiles based on real performance is not easy. However, those condition profiles usually don't give a good consistency to the safety of bridges, causing practical problems for the effective bridge management. The accuracy of performance evaluation is directly related to the accuracy of BMS. The reliability of the evaluation is important to produce the optimal solution for distributing maintenance budget reasonably. However, conventional methods of bridge assessment are not suitable for a more sophisticated decision making procedure. In this study, a method to compute quantitative performance profiles has been proposed to overcome the limitations of those conventional models. In Bridge Management Systems, the main role of performance profiles is to compute and predict the performance of bridges subject to lifetime activities with uncertainty. Therefore, the computation time for obtaining an optimal maintenance scenario is closely related to the efficiency of the performance profile. In this study, the Response Surface Method (RSM) based on independent and important design variables is developed for the rapid computation. Steel box bridges have been investigated because the number of independent design variables can be reduced significantly due to the high dependency between design variables.

• Journal of Korea Entertainment Industry Association
• /
• v.13 no.8
• /
• pp.551-561
• /
• 2019

The purpose of this study was to investigate the relationship between entrance exam stress and oral care self-efficacy in girls high school. From June to July 2018, A self-reported questionnaire was administered to 192 high school students in the G area. The data were analyzed for independent t-test, one-way ANOVA and Pearson's correlation coefficient by using SPSS/WIN 21.0 program. Among the sub-sectors of entrance exam stress, exam tension/poor was the highest with 3.07 points, followed by Insufficient spare time stress 2.83 points, future uncertainty stress 2.57 points, and parent pressure stress 2.44 points. the variables related to exam tension/poor stress were academic performance (p<.01), family income level (p<.05), Subjective oral health status(p<.05), and daily brushing frequency(p<.01). The highest level of oral care self-efficacy was 3.13 points for brushing self-efficacy, followed by dental visits 2.80 points and interdental hygiene 2.64 points. As a result of analyzing the general characteristics and oral care self-efficacy, subjects related to brushing self-efficacy were subjective oral health status, caries snacking(daily), and caries drinks(daily)(p<.01). There were negative correlations between entrance exam stress and oral care self-efficacy. The higher the entrance stress, the lower the oral care self-efficacy. To prevent oral disease and increase oral care self-efficacy of students with high entrance stress, it is necessary to provide school oral health education programs that can facilitate oral health behaviors.