• Geomechanics and Engineering
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• v.11 no.5
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• pp.607-624
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• 2016

Rockburst is becoming more serious in Chinese coal mine. One of the effective methods to control rockburst is blasting. In the paper, we monitored and analyzed the blasting waves at different blast center distances by the Hilbert-Huang transform (HHT) in a coal mine. Results show that with the increase of blast center distance, the main frequency and amplitude of blasting waves show the decreasing trend. The attenuation of blasting waves is slower in the near blast field (10-75 m), compared with the far blast field (75-230 m). Besides, the frequency superposition phenomenon aggravates in the far field. A majority of the blasting waves energy at different blast center distances is concentrated around the IMF components 1-3. The instantaneous energy peak shows attenuation trend with the blast center distance increase, there are two obvious energy peaks in the near blast field (10-75 m), the energy spectrum appears "fat", and the total energy is greater. By contrast, there is only an energy peak in the far blast field, the energy spectrum is "thin", and the total energy is lesser. The HHT three dimensional spectrum shows that the wave energy accumulates in the time and frequency with the increasing of blast center distance.

• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.402-407
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• 2011

The objectives of this study were to analyze the crown vertical structure, crown bulk density, and to develop regression models for predicting crown fuel load using the data from 10 destructively sampled Pinus densiflora trees in Bonghwa, Gyeongbuk. The fuel loads were observed higher in the middle portion of the vertical distribution of crown followed by the lower portion and upper portion of Pinus densiflora, respectively. Approximately 25% crown fuel load was found in the needle while 33% was observed in the branches with <1 cm diameter with a total of 58% available fuel loads. The average crown bulk density was $0.45kg/m^3$, and $0.27kg/m^3$ of this was available in the needles and branches with <1 cm diameters. The resulting models in linear equations were able to account for 84% and 88% of the observed variation, while the allometric equations with diameter at breast height as the single predictor showed better results to account for 90% and 95% of the observed variation in the available crown fuel loads and total crown fuel loads, respectively. The suggested equations in this study could provide quantitative fuel load attributes for crown fire behavior models and fire management of red pine stands in Bonghwa areas.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.88-96
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• 2019

The purpose of this study is to understand when forest fire as a natural phenomenon becomes constructed as social issues in Korea; how the forest fire-related discourses in the editorials reflecting the social perceptions have been changed regarding the principal subject and the measures of the forest fire management; and whether the social perception on the forest fire affects the forest fire policy of the state. From the analysis of a total of 44 editorials related to forest fires from 1988 to 2017. By the using, in the forest fire-related editorials the social perceptions on forest fires are forest fire editorials categories, main keywords, contents of social perception on 'the main subject responsible for forest fire management,' 'forest fire prevention measures,' categorization, frequency analysis and context analysis of words used. It is found that in the first-period forest fire management measures were recognized as a part of the overall forest management. In the second period, the approaches of ecological management emerged on the part of forest fire management. As forest fires were managed as a type of social disaster during the third period, such perceptions were gradually reinforced that the state should protect the people from the forest fire. In the 3rd, 4th, and 5th National Forest Plan, the forest fire management policy of each period was focused in enlightening the general public, protecting forest resources ecosystems, and preventing loss of lives, respectively. As a result of the analysis of social perceptions and comparing them to the forest fire policies through the analysis of editorials on forest fires, it is found that the social perception on the forest fire and forest fire management plan has changed having interconnections.

• Journal of the Society of Disaster Information
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• v.10 no.2
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• pp.304-311
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• 2014

Disaster Resources are the resources used in the disaster fields such as fire, typhoon, flood, collapse, flood damage, distress, relief, sanitary, explosion and so forth. The resources are distributed by the several institutes including governmental agencies, public institution, and private sectors. When the large scale disaster is occurred, many kinds of the disaster resources are needed. But it is not easy to know where institutes has the needed resources, because the resource management systems are all distributed in the each institute. To integrate or connect the resource data among the systems, it need the several kinds of coordinations such as terms, classification, and resource exchange protocols. In this paper, we propose the standard specifications and how to connect and exchange the data among the systems.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.51-56
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• 2000

Demand for new nondestructive evaluations is growing to detect tensile crack growth behavior to predict long term performance of materials and structure in aggressive environments, especially when they are in non-visible area. Acoustic emission technique is well suited to these problems and has drawn a keen interests because of its dynamic detection ability, extreme sensitivity and location of growing defects. In this study, we analysed acoustic emission signals obtained in tensile test of high strength fire resistance steel for frame structure with time frequency analysis methods. The results obtained are summaries as follows ; In the T and TN specimen consisting of ferrite and pearlite grains, most of acoustic emission events were produced near yield point, mainly due to the dislocation activities during the deformation. However, B specimen under $600^{\circ}C$ - 10min had a two peak which was attribute to the presence of martensite phase. The first peak is before yield point the second is after yield point. The sources of second acoustic emission peak were the debonding of martensite-martensite interface and the micro-cracking of brittle martensite phase. In $600^{\circ}C$-30min to $700^{\circ}C$-60min specimens, many signals were observed from area before yield point and counts were decreased after yield point.

• Wind and Structures
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• v.11 no.6
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• pp.427-440
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• 2008

Estimates of wind-induced wind effects on tall buildings are based largely on 1980s technology. Such estimates can vary significantly depending upon the wind engineering laboratory producing them. We describe an efficient database-assisted design (DAD) procedure allowing the realistic estimation of wind-induced internal forces with any mean recurrence interval in any individual member. The procedure makes use of (a) time series of directional aerodynamic pressures recorded simultaneously at typically hundreds of ports on the building surface, (b) directional wind climatological data, (c) micrometeorological modeling of ratios between wind speeds in open exposure and mean wind speeds at the top of the building, (d) a physically and probabilistically realistic aerodynamic/climatological interfacing model, and (e) modern computational resources for calculating internal forces and demand-to-capacity ratios for each member being designed. The procedure is applicable to tall buildings not susceptible to aeroelastic effects, and with sufficiently large dimensions to allow placement of the requisite pressure measurement tubes. The paper then addresses the issue of accounting explicitly for uncertainties in the factors that determine wind effects. Unlike for routine structures, for which simplifications inherent in standard provisions are acceptable, for tall buildings these uncertainties need to be considered with care, since over-simplified reliability estimates could defeat the purpose of ad-hoc wind tunnel tests.

• The Korean Journal of Emergency Medical Services
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• v.24 no.3
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• pp.89-106
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• 2020

Purpose: This study attempts to improve the status of emergency care for major trauma patients transferred by 119 paramedics by analyzing the status of emergency care and the obstacles to the spinal motion restriction (SMR) for major trauma patients. Methods: A total of 600 rescue logs were collected from major trauma patients transported by 119 paramedics in the C fire department from Jan. 1, 2015, to Dec. 31, 2017. And then, 280 questionnaires were collected from the 119 paramedics in C fire department from May 3 to Jun. 3, 2019. Data were analyzed using SPSS 24.0 version. Results: Among 499 spinal motion restriction adaptive patients, the spinal motion restriction rate was 51.1% (255 individuals). Lack of human resources and quality control problems were among the obstacles to spinal motion restriction. Conclusion: The 119 paramedics should improve their activeness and skills in performing emergency care, and since training and experience are of crucial importance, they should expand various education systematized according to demand.

• Journal of Korea Water Resources Association
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• v.53 no.6
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• pp.463-467
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• 2020

The main feature of this study is to automatically synthesize square images by sending aerial photographs and images from unmanned aerial vehicles (drons). It may be applicable to the cloud server, and to apply analytical algorithms for the suitable purpose of image processing. Drone imaging analysis is a process that can be used in various fields such as finding contaminated area of green algae, monitoring forest fire, and managing crop cultivation.

• Journal of Environmental Impact Assessment
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• v.32 no.6
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• pp.463-472
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• 2023

The amount of damage and the area of damage to forest fires are increasing globally, and the effectiveness analysis of the restoration method after the damage is performed insufficient. This study calculated the area of forest fire damage was calculated using Sentinel-2B satellite images and stack map and the intensity of forest fire damage is analyzed according to the forest type. In addition, the vegetation index was calculated using various wavelength bands. Based on the results, the vegetation resilience by the restoration method was quantitatively. As results, areas with a high proportion of coniferous forests suffered high intensity forest fire damage, and areas with a relatively high ratio of mixed and broad-leaved forests tended to have low forest fire damage. Also, artificial forests showed a recovery of about 92.7% compared to before forest fires and natural forests showed a recovery of about 99.6% from the result of analyzing vegetation resilience in artificial and natural forests after forest fires. Accordingly, it was confirmed that natural forests after forest fire damage had superior vegetation resilience compared to artificial forests. It can be proposed that this study is meaningful in providing important information for efficiently restoring the affected target site and the selection criteria for trees to reduce forest fire damage through the evaluation of vegetation resilience by the intensity of forest fire damage and restoration methods.

• Structural Engineering and Mechanics
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• v.76 no.5
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• pp.613-618
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• 2020

Exhausting oil resources and increasing pollution around the world are forcing researchers to look for new, renewable, biodegradable materials to lead sustainable development. The use of fiber reinforced composites based on natural fibres has increasingly begun as prospective materials for various engineering applications in the automotive, rail, construction and aerospace industries. The natural fiber chosen to make the composite material is plant-based fibre, e.g. jute fibre, and hemp fibre. Thermosetting polymer based Epoxy (LY556) was utilized as matrix material and The composites were produced using hand lay-up technique. The fabricated composites were tested for acoustic testing, thermo-gravimetric analysis (TGA) and flammability testing to asses sound absorption, thermal decomposition and fire resistivity of the structures. Hemp fibre composites have shown improved thermal stability over Jute fibre composites. However, the fire resistance characteristics of jute fibre composites are better as compared to hemp fibre composites. The sound absorption coefficient of composites was found to enhance with the increase of frequency.