• Fire Science and Engineering
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• v.26 no.3
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• pp.21-28
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• 2012

The objective of this study is to evaluate the prediction accuracy of FDS(Fire Dynamic Simulator) for the thermal and chemical characteristics of under-ventilated fire with unsteady fire growth in a semi-closed compartment. To this end, a standard doorway width of the full-scale ISO 9705 room was modified to 0.1 m and the flow rate of heptane fuel was increased linearly with time (until maximum 2.0 MW based on ideal heat release rate) using a spray nozzle located at the center of enclosure. To verify the capability of FDS, the predicted results were compared with a previous experimental data under the identical fire conditions. It was observed that with an appropriate grid system, the numerically predicted temperature and heat flux inside the compartment showed reasonable agreement with the experimental data. On the other hand, there were considerable limitations to predict accurately the unsteady behaviors of CO and $CO_2$ concentration under the condition of continuous fire growth. These results leaded to a discrepancy between the present evaluation of FDS and the previous evaluation conducted for steady-state under-ventilated fires. It was important to note that the prediction of transient CO production characteristics using FDS was approached carefully for the under-ventilated fire in a semi-closed compartment.

• Journal of Korean Society of Rural Planning
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• v.20 no.1
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• pp.1-12
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• 2014

Living environments in rural area have become deteriorated rapidly. Increase of aging population, decline in agricultural income, polarization of wealth in rural community due to rural returners have caused severe decline and imbalance of living environments in rural area. Responding to this circumstances, governments currently develop projects for improving living environments focusing on individual housing which were excluded from governmental supports because those had been regarded as private property. Nevertheless, there are still some gaps and problems in evaluating the quality of living environment and suggesting effective solutions. It would be because standards and guidelines of the projects have been based on urban housing system. In order to support the implementation of the projects, this research has developed an index for evaluating and monitoring the quality of living environments in rural area. By applying Delphi method, the index has been created in four categories of 'security', 'convenience', 'comfortability', and 'durability' 'Security' consists of structural safety, crime, disaster, accident prevention. 'Convenience' includes three divisions of living, traffic, farm working. 'Comfortability' is divided into sanitation, indoor environments, and aesthetic appreciation. Lastly, 'durability' has four divisions of energy conservation, environmental friendliness, efficiency, and economics. Each sub-division also has different items from three to twelves. In the case of an index for performance evaluation, items have been derived from energy conservation(6-items), and environmental friendliness(7-items). Items developed as an index for evaluating rural living environments in this research might be good background information for remodeling project in rural housing development.

• Fire Science and Engineering
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• v.29 no.2
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• pp.13-19
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• 2015

Real scale fire tests was carried out for extinguishing performance evaluation of the wetting agent. The experiment was conducted in accordance with a Class A fire extinguishing test methods specified in the 'Type Approval of the Manual System Fire Extinguisher and Technical Standards of Test'. In addition, the subjects of this experiment were the wood flour and rice husk. Fire-fighting water, the three kinds of wetting agents used in the country and this study was used, was undertaken to determine a clear discrimination of the water and wetting agent. In the experimental results, it was confirmed that the internal temperature is maintained long time in the case of water. The internal temperature were rapidly lowered in the experiment of wetting agents. Therefore, the discrimination of extinguishing ability was confirmed by the temperature distribution in accordance with time. Based on the results of this experiment, this study is expected to be used as a underlying material on presenting a method of optimized performance evaluation of wetting extinguishing agent.

• Journal of Korean Society of Disaster and Security
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• v.14 no.3
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• pp.17-27
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• 2021

In this study, classification models were built using machine learning techniques that can classify the soil creep risk into three classes from A to C (A: risk, B: moderate, C: good). A total of six machine learning techniques were used: K-Nearest Neighbor, Support Vector Machine, Logistic Regression, Decision Tree, Random Forest, and Extreme Gradient Boosting and then their classification accuracy was analyzed using the nationwide soil creep field survey data in 2019 and 2020. As a result of classification accuracy analysis, all six methods showed excellent accuracy of 0.9 or more. The methods where numerical data were applied for data training showed better performance than the methods based on character data of field survey evaluation table. Moreover, the methods learned with the data group (R1~R4) reflecting the expert opinion had higher accuracy than the field survey evaluation score data group (C1~C4). The machine learning can be used as a tool for prediction of soil creep if high-quality data are continuously secured and updated in the future.

• Journal of the Korean Society of Safety
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• v.35 no.4
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• pp.56-63
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• 2020

The government has established various policies focusing on accident prevention to reduce the accident rate in the construction industry, but the effect is still insignificant. These results allude that there are still many problems in terms of usability. Although construction safety accidents usually have characteristics that occur during construction, the laws and systems should include the pre-construction cycle (plan/order - design - construction business management- construction) to eliminate risk factors in advance. The purpose of this study is to analyze the performance evaluation of the construction safety system before construction rather than during construction. In the pre-construction phase (plan/ order-design-constuction business management), we intend to investigate and analyze measures to prevent safety accidents and identify a system that lacks the ability to implement. Specifically, we analyzed what to focus on as precautionary measures in the planning, ordering, designing, and supervising. To improve them, we made a questionnaire based on the role related to construction safety for each subject, and seek implications for lack of performance through interviews. Based on the results, some ways to improve the safety system were proposed.

• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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• pp.17-23
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• 2022

Using cement as a road subbase is economical, easily modified and supplemented and has excellent road pavement quality control. In addition, cement adheres well to sandy soils without adhesion, and it plays a role of permanently preserving adhesion in viscous soils with adhesion, so it can be widely applied as stable treatment with the advantages of increased strength, reduced compressibility. and improved durability. However, while cement is excellent in terms of strength for a road subbase, the material properties mean that it is difficult to maintain and reinforce when cracks or fractures occur due to dry shrinkage, and the pH increases in the ground due to hexavalent chromium eluting from cement. which can cause environmental problems such as groundwater contamination. Therefore, this study evaluates the usability of alternatives in the road base layer such as environmentally cementitious stabilizer and on-site soil generated from the site. We intend to reduce the environmental damage and evaluate the durability. To evaluate the applicability of the site, Environmental stability test and freeze-thaw test and wetting-drying test was conducted to evaluate the strength characteristics of alternative materials on the road through the limited performance evaluation of environmentally cementitious stabilizer. The test ranges were set at mixing ratios of 10%, 20%, and 30% and ages of three days, and 28 days old to evaluate the early strength and reference strength according to the mixing ratio of the environmentally cementitious stabilizer.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.38-50
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• 2022

Purpose: The goal of this research is to create a numerical analytic database that may assist fire prevention managers and building officials in prioritizing items that need to be addressed in order to improve evacuation safety performance while working within a constrained budget and time frame. Method: It was carried out utilizing the CFD Tool, a quantitative evaluation approach, to assess evacuation safety. One direct staircase-type apartment houses and one corridor-type apartment were chosen to make it. Result: In the fire compartment category, Apartment A's evacuation time was around 130 percent longer than that of sprinkler facilities. Conclusion: Fire prevention managers and building officials feel that starting with a single level and implementing "dwelling unit separations" will increase evacuation safety, and that maintaining fire compartments and sprinkler systems at all times will be effective. Because of the limited characteristics of smoke propagation in corridor-type apartments compared to direct staircase-type flats, it is thought that fire extinguishing equipment should be addressed.

• Fire Science and Engineering
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• v.30 no.1
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• pp.6-11
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• 2016

This study analyzed the performance of smoke exhaustion installed to secure the life safety from the smoke each opening modes, as performing the simulation on the Jeju regions generating to strong windy using CONTAM. We assessed the effectiveness of the system under conditions of high external winds as well as an ambient wind conditions. It also assessed the relative effectiveness of opening all vents versus opening only those vents which served rooms in which the fire was located. This study revealed external winds exerted a substantial impact on the performance of the smoke ventilation system. It was found that opening the ventilation system in the room containing the fire resulted in a greater performance than opening vents in both fire in all rooms. The reduced performance of the smoke ventilation system upon the opening of all vents is thought to be due to the intrusion of outside air, and the establishment of unfavorable air circulation, caused by the negative pressure generated in the building.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.463-478
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• 2021

The subjects of the study are the sedimentary rock slope of the Mesozoic Gyeongsang Supergroup, which has a high risk of failure. The orientation of the slope-face represents a variety of changing characteristics. The rocks of the slope shall be sandstone, siltstone and dacite, and discontinuities shall develop beddings, shear joints, extension joints, and dacite dyke boundary planes. The type and scale of failure varies depending on the type of rock and the strike/dip of the discontinuities, but the toppling failure prevails. Based on the face-mapping data, SMR, physical and mechanical testing of rocks, analysis and review of the stereonet projections and the critical equilibrium analysis, all four representative sections required a countermeasure method because the acceptable safety factor during dry and rainy seasons were far below Fs = 1.5 and Fs = 1.2. After applying the countermeasure method, both the dry and wet conditions of the slope exceeded the allowable safety factor. In particular, the face-mapping data of the slope-face, the geological cross-sections of several representative sections perpendicular to the slope-face, and the critical equilibrium analysis and the presentation of countermeasure methods that have been reviewed based on them are expected to be reasonable tools for the slope stability. In addition, it will be possible to use it as basic data for performance evaluation for slope maintenance.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.60-72
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• 2023

The purpose of this study is to measure the change in evacuation time at high schools according to the change in hallway width using an evacuation simulation program and to analyze the result of such change. In order to measure the evacuation time according to the change in the hallway width according to the 「Rules on the Standards for Evacuation and Fire Protection Structures of Buildings」 and to analyze the change in evacuation time resulted from the increase in the number of occupants, a scenario was constructed by applying the 「performance-oriented design method and standard for firefighting facilities, etc.」. As a result of the experiment, it was found that the evacuation time was the shortest when the width of the hallway was the widest, which was 3m. On the other hand, the evacuation time took the longest at 1.8m, which was the width of the second narrowest hallway. For the safety of high school students who spend a lot of time at school, it is necessary to secure a wide hallway width when building a new school or to provide periodic safety education in the case of an existing school whose hallways are considered narrow.