• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.73-76
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• 2008

The damage of earthquakes have to achieve by probabilistic evaluation because of uncertainty of earthquake. Fragility analysis is a useful tool for predicting the probability of damage induced by the probable earthquake. This paper presents the probability of damage as a function of peak ground acceleration and estimates the probability of five damage levels for the pier of prestressed concrete (PSC) bridge subjected to given ground acceleration. At each 100 artificial earthquake motions were generated in terms of soil conditions, and nonlinear time domain analyses were performed for the damage states of the pier of PSC bridge structures. These damage states are described by displacement ductility result from seismic performance based on existing research results. Using the damage states and ground motion parameters, five fragility curves for the pier of PSC bridges with five types of dominant frequencies were constructed assuming a log-nomal distribution. It was found that there was a significant effect on the fragility curves due to the dominant frequencies.

• Journal of Ecology and Environment
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• v.41 no.2
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• pp.34-44
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• 2017

Background: Monitoring terrestrial vegetation cover condition is important to evaluate its current condition and to identify potential vulnerabilities. Due to simplicity and low cost, point intercept method has been widely used in evaluating grassland surface and quantifying cover conditions. Field-based digital photography method is gaining popularity for the purpose of cover estimate, as it can reduce field time and enable additional analysis in the future. However, the caveats and uncertainty among field-based vegetation cover estimation methods is not well known, especially across a wide range of cover conditions. We compared cover estimates from point intercept and digital photography methods with varying sampling intensities (25, 49, and 100 points within an image), across 61 transects in typical steppe, forest steppe, and desert steppe in central Mongolia. We classified three photosynthetic groups of cover important to grassland ecosystem functioning: photosynthetic vegetation, non-photosynthetic vegetation, and bare soil. We also acquired normalized difference vegetation index from satellite image comparison with the field-based cover. Results: Photosynthetic vegetation estimates by point intercept method were correlated with normalized difference vegetation index, with improvement when non-photosynthetic vegetation was combined. For digital photography method, photosynthetic and non-photosynthetic vegetation estimates showed no correlation with normalized difference vegetation index, but combining of both showed moderate and significant correlation, which slightly increased with greater sampling intensity. Conclusions: Results imply that varying greenness is playing an important role in classification accuracy confusion. We suggest adopting measures to reduce observer bias and better distinguishing greenness levels in combination with multispectral indices to improve estimates on dry matter.

• Journal of the Korean earth science society
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• v.25 no.3
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• pp.194-204
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• 2004

The purpose of this literature review is to investigate what kinds of research have been done about scientific inquiry in terms of scientific argumentation in the classroom context from the upper elementary to the high school levels. First, science educators argued that there had not been differentiation between authentic scientific inquiry by scientists and school scientific inquiry by students in the classroom. This uncertainty of goals or definition of scientific inquiry has led to the problem or limitation of implementing scientific inquiry in the classroom. It was also pointed out that students' learning science as inquiry has been done without opportunities of argumentation to understand how scientific knowledge is constructed. Second, what is scientific argumentation, then? Researchers stated that scientific inquiry in the classroom cannot be guaranteed only through hands-on experimentation. Students can understand how scientific knowledge is constructed through their reasoning skills using opportunities of argumentation based on their procedural skills using opportunities of experimentation. Third, many researchers emphasized the social practices of small or whole group work for enhancing students' scientific reasoning skills through argumentations. Different role of leadership in groups and existence of teachers' roles are found to have potential in enhancing students' scientific reasoning skills to understand science as inquiry. Fourth, what is scientific reasoning? Scientific reasoning is defined as an ability to differentiate evidence or data from theory and coordinate them to construct their scientific knowledge based on their collection of data (Kuhn, 1989, 1992; Dunbar & Klahr, 1988, 1989; Reif & Larkin, 1991). Those researchers found that students skills in scientific reasoning are different from scientists. Fifth, for the purpose of enhancing students' scientific reasoning skills to understand how scientific knowledge is constructed, other researchers suggested that teachers' roles in scaffolding could help students develop those skills. Based on this literature review, it is important to find what kinds of generalizable teaching strategies teachers use for students scientific reasoning skills through scientific argumentation and investigate teachers' knowledge of scientific argumentation in the context of scientific inquiry. The relationship between teachers' knowledge and their teaching strategies and between teachers teaching strategies and students scientific reasoning skills can be found out if there is any.

• Journal of Digital Contents Society
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• v.19 no.1
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• pp.165-171
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• 2018

Shadow is a physical phenomenon observed in natural scenes and has a negative effect on various image processing systems such as intelligent video surveillance, traffic surveillance and aerial imagery analysis. Therefore, shadow detection should be considered as a preprocessing process in all areas of computer vision. In this paper, we define and analyze various feature elements for shadow detection in a single natural image that does not require a reference image. The shadow elements describe the intensity, chromaticity, illuminant-invariant, color invariance, and entropy image, which indicate the uncertainty of the information. The results show that the chromaticity and illuminant-invariant images are effective for shadow detection. In the future, we will define a fusion map of various shadow feature elements, and continue to study shadow detection that can adapt to various lighting levels, and shadow removal using chromaticity and illuminance invariant images.

• Geomechanics and Engineering
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• v.8 no.2
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• pp.153-171
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• 2015

The observational method in tunnel engineering allows the evaluation in real time of the actual conditions of the ground and to take measures if its behavior deviates considerably from predictions. However, it lacks a consistent and structured methodology to use the monitoring data to adapt the support system in real time. The definition of limit criteria above which adaptation is required are not defined and complex inverse analysis procedures (Rechea et al. 2008, Levasseur et al. 2010, Zentar et al. 2001, Lecampion et al. 2002, Finno and Calvello 2005, Goh 1999, Cui and Pan 2012, Deng et al. 2010, Mathew and Lehane 2013, Sharifzadeh et al. 2012, 2013) may be needed to consistently analyze the problem. In this paper a methodology for the real time adaptation of the support systems during tunneling is presented. In a first step limit criteria for displacements and stresses are proposed. The methodology uses graphics that are constructed during the project stage based on parametric calculations to assist in the process and when these graphics are not available, since it is not possible to predict every possible scenario, inverse analysis calculations are carried out. The methodology is applied to the "Bois de Peu" tunnel which is composed by two tubes with over 500 m long. High uncertainty levels existed concerning the heterogeneity of the soil and consequently in the geomechanical design parameters. The methodology was applied in four sections and the results focus on two of them. It is shown that the methodology has potential to be applied in real cases contributing for a consistent approach of a real time adaptation of the support system and highlight the importance of the existence of good quality and specific monitoring data to improve the inverse analysis procedure.

• Journal of the Korean earth science society
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• v.41 no.4
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• pp.323-343
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• 2020

Observation data measured at Ieodo Ocean Research Station (IORS) have been utilized in oceanographic and atmospheric studies since 2003. Sea level data observed at the IORS have not been paid attention as compared with many other variables such as aerosol, radiation, turbulent flux, wind, wave, fog, temperature, and salinity. Total sea level rises at the IORS (5.6 mm yr^-1) from both satellite and tide-gauge observations were higher than those in the northeast Asian marginal seas (5.4 mm yr^-1) and the world (4.6 mm yr^-1) from satellite observation from 2009 to 2018. The rates of thermosteric, halosteric, and steric sea level rises were 2.7-4.8, -0.7-2.6, 2.3-7.4 mm yr^-1 from four different calculating methods using observations. The rising rate of the steric sea level was higher than that of the total sea level in the case with additional data quality control. Calculating the non-steric sea level was not found to yield meaningful results, despite the ability to calculate non-steric sea level by simply subtracting the steric sea level from total sea level. This uncertainty did not arise from the data analysis but from a lack of good data, even though tide, temperature, and salinity data were quality controlled two times by Korea Hydrographic and Oceanography Agency. The status of the IORS data suggests that the maintenance management of observation systems, equipment, and data quality control should be improved to facilitate data use from the IORS.

• Journal of the Economic Geographical Society of Korea
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• v.12 no.4
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• pp.454-476
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• 2009

The purpose of this paper is to examine relation between trust building level and linkages's spatial characteristics on the logistics & storage industry of Busan. As a result, First, long-term & repeated interaction, information sharing & reciprocity, and interdependence & asset specificity have an important effect upon the micro trust which implies the highest trust. Proximity and uncertainty impact on the meso trust, the trust of middle level. Culture, norm, and formal institution of firms affect the macro trust, the lowest level of trust. Second, the micro, the meso, and the macro trusts mainly form in the local scale where spatial proximity is great. The higher the trust building levels become, the more spatial dimensions by linkage expand to national and international dimension, respectively. Third, these results appear more clearly in the output linkage than input linkage, in the service areas-many firm, in the horizontal linkage than vertical linkage, in the advanced evolution phases of firm connection, and in the supply chain management than outsourcing.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1315-1331
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• 2014

Replacement rates which shows the ratio of retirement income relative to preretirement income is used for a valuable evaluation measures while discussing social security benefit levels or the adequacy of retirement income. However, replacement rates has been only used for an index for evaluating benefit level at the time of retirement or specific retirement period in advanced research projects. This article analyzes how much the uncertainty of survival has an influence on retirement income, and shows replacement rates in conformity with the period of survival as an index. The researchers named this index lifetime income replacement rates. Analysis based on this index shows both life replacement income rates of 38.3% in men's case and of 41.1% in women's case while enrolled for 20years in three pension plans - national pension, retirement pension and individual annuity.

• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1324-1329
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• 2018

This study presents a practical application of complementary safety indicators, which can be applied in a safety assessment of a radioactive waste repository by excluding a biosphere simulation and comparing the artificial radiation originating from the repository with the background natural radiation. Complementary safety indicators (radiotoxicity flux from geosphere and radiotoxicity concentration in seawater) were applied in the safety assessment of a rock-cavern type low and intermediate level radioactive waste (LILW) repository in the Republic of Korea. The natural radionuclide ($^{40}K$, $^{226,228}Ra$, $^{232}Th$, and $^{234,235,238}U$) concentrations in the groundwater and seawater at the Gyeongju LILW repository site were measured. Based on the analyzed concentrations of natural radionuclides, the levels of natural radiation were determined to be $8.6{\times}10^{-5}$ - $8.0{\times}10^{-4}Sv/m^2/yr$ and $6.95{\times}10^{-5}Sv/m^3$ for radiotoxicity flux from the geosphere and radiotoxicity concentration in seawater, respectively. From simulation results obtained using a Goldsim-based safety assessment model, it was determined that the radiotoxicity of radionuclides released from the repository is lower than that of the natural radionuclides inherently present in the natural waters. The applicability of the complementary safety indicators to the safety case was discussed with regard to reduction of the uncertainty associated with biosphere simulations, and communication with the public.

• Journal of Astronomy and Space Sciences
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• v.37 no.4
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• pp.237-247
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• 2020

The ground tracking support is a critical factor for the navigation performance of spacecraft orbiting around the Moon. Because of the tracking limit of antennas, only a small number of facilities can support lunar missions. Therefore, case studies for various ground tracking support conditions are needed for lunar missions on the stage of preliminary mission analysis. This study analyzes the ground supporting condition effect on orbit determination (OD) of Korea Pathfinder Lunar Orbiter (KPLO) in the lunar orbit. For the assumption of ground support conditions, daily tracking frequency, cut-off angle for low elevation, tracking measurement accuracy, and tracking failure situations were considered. Two antennas of deep space network (DSN) and Korea Deep Space Antenna (KDSA) are utilized for various tracking conditions configuration. For the investigation of the daily tracking frequency effect, three cases (full support, DSN 4 pass/day and KDSA 4 pass/day, and DSN 2 pass/day and KDSA 2 pass/day) are prepared. For the elevation cut-off angle effect, two situations, which are 5 deg and 10 deg, are assumed. Three cases (0%, 30%, and 50% of degradation) were considered for the tracking measurement accuracy effect. Three cases such as no missing, 1-day KDSA missing, and 2-day KDSA missing are assumed for tracking failure effect. For OD, a sequential estimation algorithm was used, and for the OD performance evaluation, position uncertainty, position differences between true and estimated orbits, and orbit overlap precision according to various ground supporting conditions were investigated. Orbit prediction accuracy variations due to ground tracking conditions were also demonstrated. This study provides a guideline for selecting ground tracking support levels and preparing a backup plan for the KPLO lunar mission phase.