• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.662-669
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• 2018

Recently, the installation of submarine power cables is under consideration due to the increase of electric power usage and the development of the offshore wind farm in island areas, including Jeju. In order to protect power cables installed on the seabed, it is necessary to calculate the burial depth based on the characteristics of anchoring, dragging and fishing, etc. However, there is no design standard related to the size of target ships to protect the cables in Korea. In this study, we analyzed the design standards for the protection of domestic submarine pipelines similar to submarine cables, and developed the risk matrix based on the classification by emergency anchoring considering the installation environment, then designed the size of target ships according to the cumulative function scale by ship size sailing through the sea concerned. Also, we linked marine accident conditions, such as anchoring, dragging, etc. and the environmental conditions such as current, sea-area depth of installation etc. to the criteria of the protection of submarine cable, and examined the size of specific target ships by dividing the operating environment of ships into harbor, coastal and short sea. To confirm the adequacy and availability of the size of target ships, we verified this result by applying to No. 3 submarine power cables, which is to be installed in the section from Wando to Jeju Island. This result is expected to influence in the development of a protection system for submarine cables and pipelines as well as the selection of anchor weight according to the determination of burial depth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4863-4870
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• 2015

Currently, as a priority to secure the safety of the railway signalling system, verification for satisfy of the safety integrity requirements(SIR) is required to the essential elements. Safety Integrity Requirements(SIR) verification is performed based on the system safety analysis. But the probability of securing basic data for system safety analysis significantly dropped because there is no experience yet performed in the country. Therefore we are had to rely on a qualitative analysis. There are methods such as qualitative risk analysis matrix, and risk graphs. The qualitative analysis is wide, the width of the accident. However, the reliability of the result is significantly less has a disadvantage. Therefore, it should be parallel quantitative safety analysis of the system/products in order to compensate for the disadvantages of the qualitative analysis. This paper presents a quantitative safety analysis method to overcome the disadvantages of the qualitative analysis. And through a result, highly reliable Safety Integrity Requirements(SIR) verification measures proposed. Verification results, the dangerous failure incidence for vital data processing device was calculated to be $1.172279{\times}10^{-9}$. The result was verified to exceed the required safety integrity targets more.

• Korean Journal of Environment and Ecology
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• v.24 no.2
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• pp.178-185
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• 2010

The purpose of this study is to verify the effectiveness of the biotope model in applying and developing Korean urban forests. We found that there are 17 biotope assessment indicators, including forest layer structure, site conditions, ratio of broad-leaved trees, species richness, etc. In terms of correlation analysis between indicators, the stand ages and the period of space formation have the highest relativity(coefficient 0.684). On the other hand, indicators that have negative relativity are layer structure and risk, with a coefficient of -0.412. Ten models were developed for the multiple regression analysis. 10 variables(site conditions(X2), ratio of broad-leaved trees(X3) and so forth except layer structure(X1), species richness(X4)) were found to have a 95% significance level The results from comparing the regression model and adding-up estimation matrix, the most accurate one was Model 3, which has a 91.7% out of the 10 models. However more monitoring will be needed to improve the accuracy of models for the Korean urban forests in future.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.2
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• pp.159-172
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• 2021

This study is an action study that plans a instructional strategy for improving experimental activities and interactions in online science classes and suggests improvement plans based on the results. To this end, from July 7 to September 9, 2020, the 'Earth and the Moon' unit class was conducted for 20 6th grade elementary school students located in G Metropolitan City. For the class, smart devices and alternative experiments were planned in the experimental activity category, and an online chat room and Q&A strategy were planned in the interaction category. Among the collected data, class activity papers, homework assignments, reflection journals, online conversation contents, and Q&A contents were input into the matrix and analyzed by writing analytical texts. As a result of the implementation, smart devices and alternative experiments provided opportunities for exploration, but there was a risk of misconception formation and hindered experimental activities. The online chat room and Q&A provided opportunities for communication and examination and feedback on scientific concepts. Through this action study, the researcher was able to reflect on the class while writing class reflection notes, and suggested the role of smart devices in terms of the effectiveness and efficiency of science classes.

• Journal of the Korean Geotechnical Society
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• v.26 no.3
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• pp.59-68
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• 2010

Systematic risk management is necessary in grand scaled urban construction because of the existence of complicated and various risk factors. Problems of obstructions, adjacent structures, safety, environment, traffic and geotechnical properties need to be solved because urban construction is progressed in limited space not as general earthwork. Therefore the establishment of special risk management system is necessary to manage not only geotechnical properties but also social and cultural uncertainties. This research presents the technique analysis by the current state of risk management technique. Risk factors were noticed and the importance of each factor was estimated through survey. The systemically categorized database was established. Risk extraction module, matrix and score module were developed based on the database. Expected construction budget and time distribution can be computed by Monte Carlo analysis of probabilities and influences. Construction budgets and time distributions of before and after response can be compared and analyzed 80 the risks are manageable for entire whole construction time. This system will be the foundation of standardization and integration. Procurement, efficiency improvement, effective time and resource management are available through integrated management technique development and application. Conclusively decrease in cost and time is expected by systemization of project management.