• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.208-209
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• 2022

This study aims to analyze the risk factors caused by object damage and third-party damage loss in actual bridge construction based on past insurance premium payment data from major domestic insurers for bridge construction projects, and develop a quantitative loss prediction model. For the development of quantitative bridge construction loss model, the dependent variable was selected as the loss ratio, and the independent variable adopted 1) Technical factors: superstructure type, foundation type, construction method, and bridge length 2) Natural hazards: flood anf Typhoon, 3) Project information: total construction duration, total cost and ranking. Among the selected independent variables, superstructure type, construction method, and project period were shown to affect the ratio of bridge construction losses, while superstructure, foundation, flood and ranking were shown to affect the ratio of the third-party losses.

• Korea Science and Art Forum
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• v.37 no.5
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• pp.239-248
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• 2019

This study started from the need to improve one of shortcomings of synthetic PVAc adhesives - potential physical harm and environmental hazards to the workers or their users. As a matter of fact, PVAc adhesives are currently mainly used because of their convenience and economy for the production of woodcrafts. The purpose of this study was to develop natural adhesives through research on natural adhesives in step with the current increase of societal attention to environmental friendliness and rapid surge in their demand in the face of such problems. So, the study attempted research on the bases to develop natural adhesives for woodcraft, using cellulose extracts from wood - natural adhesive material. The findings of the study were as follows. Firstly, natural adhesives showed the improved effect in the field of adhesive strength, a basic physical property by 0.2 - 4 times compared with the existing materials and the study confirmed they had the similar or stable pH value. Besides, they had good reversibility, demonstrating their basic physical property as a natural adhesive for woodcraft. While, their durability to ultraviolet ray degradation also showed an excellent result value being better by 1.5 - 8.5 times than the existing materials. The study expects natural adhesives with improved and better performances compared with the existing materials could be developed, if further research on adhesive strength, antibiosis, conservative property were to continue by developing refinery technology for cellulose extracts from wood and rendering the functionality to them.

• Economic and Environmental Geology
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• v.40 no.1 s.182
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• pp.115-128
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• 2007

This study proposed a modified logistic regression model for a probabilistic prediction of debris flow on natural terrain at the granitic rock area. The modified model dose not contain any categorical factors that were used in the previous model and secured higher reliability of prediction than that of the previous one. The modified model is composed of lithology, two factors of geomorphology, and three factors of soil property. Verification result shows that the prediction reliability is more than 86%. Using the modified regression model, the landslide prediction maps were established. In case of Sacheon area, the prediction map showed that the landslide occurrence was not well corresponded with the model since, even though the forest-fred area was distributed on the center of the model, no factors were considered for the landslide predictions. On the other hand, the prediction model was well corresponded with landslide occurrence at Jumunjin-Yeongok area. The prediction model developed in this study has very high availability to employ in other granitic areas.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.225-233
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• 2007

The engineering properties of surface soils in natural terrain are changed due to wildfire. This change of engineering properties induced by wildfire is related to landslides occurrence. To investigate the change of soil properties caused by wildfire, the various soil tests are performed. The soil samples are obtained from the recently burned slopes of Yangyang area, Kangwon Province. The soil samples obtained from the burned slopes are classified into three types depending on the burning grade: the perfect burning grade, the intermediate burning grade, the non-burning grade. As the result of tests, the specific gravity and the dry unit weight of soils obtained from perfect and alternative burning grades are less than those of soils obtained from non-burning grade. It judges that an electronic force, ionic components and of soils are changed and organic matters in soils are burned by wildfire. The permeability of soil obtained from alternative burning grade is the lowest and that of soil obtained from perfect burning grade is the highest. The water-repellent layer is formed on soil surface by wildfire. The water-repellent layer is existed at the area of alternative turning grade, while the layer is not existed at the area of perfect burning grade. The water-repellent layer is collapsed in high temperature more than about $400^{\circ}C$.

• Korean Journal of Medicinal Crop Science
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• v.24 no.2
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• pp.143-151
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• 2016

Background: The public has increasing concerns about herbal crops owing to insufficient information on biological hazards such as foodborne pathogens. Therefore, the objective of this study is the development of a herbal crop quality control system through monitoring with biological hazard analysis. Today, it is estimated that millions of people become ill every year from food contamination. The public demands agricultural products of stable and consistent quality. Governments have the responsibility of establishing the standards, legislation and enforcement programs necessary to control food quality and safety. However, research on the biosafety of herbal crop products is still insufficient. Therefore, the implementation of monitoring systems with high standards is critical for public safety. Methods and Results: In this study, we collected 52 samples of herbal crop products, and conducted both quantitative and qualitative biological hazard analysis. With biological hazard analysis, aerobic bacteria, Staphylococcus aureus, Salmonella spp., Escherichia coli, Coliforms, and Listeria spp. could be detected. Conclusions: Herbal crops were found to be contaminated with aerobic bacteria at $3.69{\pm}0.32log\;CFU/g$. Staphylococcus aureus, Salmonella spp., Escherichia coli, Coliforms, and Listeria spp. were not detected in any of the samples. This research suggests that continuous monitoring of biological hazards is required to improve the quality of herbal crops.

• The Journal of Engineering Geology
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• v.34 no.2
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• pp.163-171
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• 2024

Changes in the soil layer on Dokdo are important both academically and with regard to sustainable conservation and utilization of the islands. Continuous investigation and observation are necessary, as the soil layer is essential to the growth of plants and, therefore, the islands' ecosystem. Such work was carried out for about 8 years using soil erosion measuring bars, which are durable and facilitate simple monitoring of changes in the soil layer. Each bar comprised a rod measuring 30~50 cm long and 1.5 cm in diameter, and the use of stainless steel afforded resistance to corrosion caused by sea breezes. Six measuring bars were installed in the soil layers of each of two islands, Dongdo and Seodo, and measurements were taken one to three times a year from 2014 to 2021. The field measurements indicate that soil was deposited on Dongdo but eroded on Seodo during the observation period. As the measuring bars on Dongdo were located in the central and lower parts of the island, the observed changes in the soil layer resulted mainly from sedimentation of material eroded by weathering or soil runoff from the upper part of the island. In contrast, the measurement locations on Seodo were located in the upper and central parts of the island, where soil erosion and runoff diminished the soil layer at the observation points.

• Journal of Korean Neurosurgical Society
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• v.59 no.1
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• pp.11-16
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• 2016

Objective : We conducted a retrospective cohort study to elucidate the natural course of unruptured intracranial aneurysms (UIAs) at a single institution. Methods : Data from patients diagnosed with UIA from March 2000 to May 2008 at our hospital were subjected to a retrospective analysis. The cumulative and annual aneurysm rupture rates were calculated. Additionally, risk factors associated with aneurysmal rupture were identified. Results : A total of 1339 aneurysms in 1006 patients met the inclusion criteria. During the follow-up period, 685 aneurysms were treated before rupture via either an open surgical or endovascular procedure. Six hundred fifty-four UIAs were identified and not repaired during the follow-up period. The mean UIA size was $4.5{\pm}3.2mm$, and 86.5% of the total UIAs had a largest dimension <7 mm. Among these UIAs, 18 ruptured at a median of 1.6 years (range : 27 days to 9.8 years) after day 0. The annual rupture risk during a 9-year follow-up was 1.00%. A multivariate Cox proportional hazards analysis revealed that the aneurysm size and a history of subarachnoid hemorrhage (SAH) were statistically significant risk factors for rupture. For an aneurysms smaller than 7 mm in the absence of a history of SAH, the annual rupture risk was 0.79%. Conclusion : In our study, the annual rupture risk for UIAs smaller than 7 mm in the absence of a history of SAH was higher than that of Western populations but similar to that of the Japanese population.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1002-1010
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• 2015

Natural gas hydrates are newly emerging as an environment-friendly source of energy to substitute for fossil fuels in the 21stcentury.NGHs are reported to holds much amounts of natural gas (up to 182 standard volumes of gas per volume of hydrate); they are easy to store and safe to carry at about minus 20 degree Celsius under atmospheric pressure because of the self-preservation phenomenon of gas hydrates. The transporting method by gas-ice-hydrate ship carriers has been introduced and developed by a variety of industry and research institutions. Our team has been conducted to develop NGH total systems, including a breakthrough NGH carrier for sea transportation, since 2011. The NGH pellet carrier does not require a separate cooling system for cargo, and the initial temperature is maintained through insulation of the cargo tanks throughout the transport to the final destination. The heat conducted from the exterior and passing through the insulation material of the hull should be cut off as much as possible, but heat inflow inside the cargo tank from an external source is inevitable during transport. In this study, the heat transfer in a cargo tank of a 115K NGH carrier was analyzed through simulation with a commercial CFD code to estimate the boil-off gas/boil-off rate on the developed carrier and understand major hazards that could significantly impact the safety of the vessel.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.4
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• pp.47-53
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• 2011

As global warming and has caused the number of abnormal changes, much damage has occurred recently in Korean Peninsula from natural disaster. To prevent and cope with these annually repeated natural hazards, scientific analysis are needed in Disaster Management, including systematic management. In this study, As part of scientific disaster prevention measures, digital image based hazard map for solution to overcome the existing hazard map with schematic representation was constructed. which was combined digital image, digital map and hazard information, and than hazard information system was developed using the hazard map. The hazard information map and hazard information system are able to provide great service to the public and to support quick decision making for hazard management and analysis of natural hazard damage.

• Journal of the Korean association of regional geographers
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• v.19 no.4
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• pp.580-599
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• 2013

After the unification of Three Kingdoms, Silla Dynasty had been on the prosperity with continuous population growth during approximately 120 years. However, Unified Silla Dynasty experienced 11 times of famine and bad year by frequent droughts during 50 years since the late 8th century, and these caused to political, economic and social changes. It is evident that Silla Dynasty slowly declined by the droughts and famines, although ancient records described as still on glory days. Since then, national power of Unified Silla Dynasty was abruptly weakened by migration of residents, and 9 times of rebellion or revolt occurred during 50 years in the late 9th century. As a result, political and social agitations reached the maximum. These led to the collapse of the Unified Silla Dynasty, and King Gyeongsoon handed over the dynasty to King Wanggeon, a founder of Goryeo Dynasty. These resulted from the 500-year-cycle droughts and human activities that seriously devastated the vegetations by using trees as an energy source for hundreds of thousands people during several centuries. The devastation of vegetation destroyed farm lands and led to large changes in river and groundwater systems, and eventually, increased damages by droughts.