• Explosives and Blasting
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• v.41 no.4
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• pp.1-8
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• 2023

On August 4, 2020, 2750 tons of ammonium nitrate stored in a storage warehouse at the Port of Beirut exploded. This explosion is said to be the largest ammonium nitrate explosion ever. By applying the TNT equivalency method, TNT equivalent amount corresponding to the explosion energy of 2750 tons of ammonium nitrate was calculated, and it is found to be 856 tons. Overpressure and impulse were calculated in a range up to 3600 m from the blast using the Kingery-Bulmash explosion parameter calculator tool. As the distance from the explosion center increases, the overpressure and impulse decrease exponentially, but the overpressure decreases more significantly, showing that overpressure is more affected by distance than the impact. As a result of applying the damage criteria to evaluate the effects of overpressure and impulse on the structure, the critical distances at which partial collapse, major damage, and minor damage to the structure occur are found to be approximately 500, 800, and 2200 m from the center of the explosion, respectively. The probit function was applied to evaluate the probability of damage to structures and human body. The points where the probability of collapse, major damage, minor damage, and breakage of window-panes to structures are greater than 50% are found to be approximately 500, 810, 2200, and 3200 m, respectively. For people within 200 m from the center of the explosion, the probability of death due to lung damage is more than 99%, and the 50% probability of eardrum rupture is approximately 300 m. The points with a 100% probability of death due to skull rupture and whole body impact due to whole body displacement are evaluated to be 300 and 100 m, respectively.

• Journal of Ecology and Environment
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• v.41 no.11
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• pp.310-317
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• 2017

Background: Many studies about climate-related range shift of plants have focused on understanding the relationship between climatic factors and plant distributions. However, consideration of adaptation factors, such as dispersal and plant physiological processes, is necessary for a more accurate prediction. This study predicted the future distribution of marlberry (Ardisia japonica), a warm-adapted evergreen broadleaved shrub, under climate change in relation to the dispersal ability that is determined by elapsed time for the first seed production. Results: We introduced climate change data under four representative concentration pathway (RCP 2.6, 4.5, 6.0, and 8.5) scenarios from five different global circulation models (GCMs) to simulate the future distributions (2041~2060) of marlberry. Using these 20 different climate data, ensemble forecasts were produced by averaging the future distributions of marlberry in order to minimize the model uncertainties. Then, a dispersal-limited function was applied to the ensemble forecast in order to exam the impact of dispersal capacity on future marlberry distributions. In the dispersal-limited function, elapsed time for the first seed production and possible dispersal distances define the dispersal capacity. The results showed that the current suitable habitats of marlberry expanded toward central coast and southern inland area from the current southern and mid-eastern coast area in Korea. However, given the dispersal-limited function, this experiment showed lower expansions to the central coast area and southern inland area. Conclusions: This study well explains the importance of dispersal capacity in the prediction of future marlberry distribution and can be used as basic information in understanding the climate change effects on the future distributions of Ardisia japonica.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.6
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• pp.29-41
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• 2012

This study was conducted in Ningxia Hui autonomous region, located at southern part of Mu Us sand land in China. To investigate relationships between windbreak effect and installation cost of sand barriers, plastic net is utilized by using four kind of heights (0.2, 0.3, 0.4 and 0.5m) and four kind of porosities (20, 30, 50 and 70%). These heights and porosities are measured for estimating distances for effective windbreak. It is shown that porosity and the distance have a positive relationship at same heights and porosity on ground indicates a constant figure when height reaches a certain level, regardless of the porosity. This implies that there is a difference of level of windbreak with different porosities; however, distance of windbreak effect is same at the same height of sand barrier. As a result of comparison between porosity of sand barrier on the ground and installation cost in each sand barrier with various heights and porosities (16 combinations), 0.4m and 0.5m height sand barriers describe highest economical efficiency. Within two variables, we concluded that height has a higher impact on windbreak effect than porosity.

• ALGAE
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• v.17 no.1
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• pp.41-51
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• 2002

Three dominant rocky intertidal macroalgae, the fucoids Fucus gardneri and Pelvetiopsis limitata (Phaeophyta) and the red alga Mazzaella cornucopiae (= Iridaea cornucopiae) on the west coast of Vancouver Island, British Columbia, Canada were used in a series of field experiments to examine interspecific interactions. These experiments showed complex patterns which included an interchange of negative (inhibition) and positive (facilitation) interactions depending on neighbor distance. Less fucoid recruitment occurred in the plots with greater percent cover of a turfforming red alga, M. cornucopiae. However, experimentally removing Mazzaella turf (the turf was considered to be "blocking" fucoid recruits or "shading" growing recruits) did not increase recruitment. This result indicated that there may be another factor(s) involved in the survivorship of juvenile fucoids in the turf-removed plots. Morphological differences in adult plants between Mazzaella and the two fucoids resulted in another type of interaction; these began when fucoids successfully settled and grew nearby or within the red algal turf. By monitoring microhabitat at the individual plant level for two years, I found that survivorship of fucoid recruits showed different species-specific patterns. The patterns also varied as the microhabitat changed from Mazzaella turf edge to open space. For F. gardneri, longevity of P.limitata at all distances tested was similar. A reason for greater longevity of F. gardneri individuals at edge microhabitats may be that these sites have one side open to light and nutrients and another site that buffers them from desiccation and wave impact. In the Mazzaella-Fucus interaction, neighbor distance was a key factor in determining whether the outcome of the interaction would be competition or facilitation (or protection). This study provides experimental evidence that detectable biological interactions occur in this upper intertidal algal community where physical conditions are usually severe, and also indicates the importance of small scale examination in understanding macroalgal interactions in intertidal habitats.

• Korean Journal of Construction Engineering and Management
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• v.17 no.1
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• pp.101-109
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• 2016

During road construction, minimizing haul and return distances as well as keeping a balance between cut and fill quantities are two of the key tasks for earthmoving operation planning. The result of the earthwork planning has a significant impact on the construction cost and duration. Although there have been research efforts regarding optimized earthwork planning using linear programming, the current practice of selecting earthwork planning methods typically depends on a field manager's intuitive and/or experimental knowledge. Furthermore, there is no system considering earthwork influential field factors including the transportation distance, the earthwork quantity, and the recycling ratio of earth volume. Therefore, this research focuses on the development of such a model for planning the optimized earthwork to increase the efficiency of a road construction. The proposed model is developed based upon the transportation problem method which is a part of Linear Programming. The application result of optimization model on a case study shows that the duration and cost for earthwork ha sbeen reduced approximately 19% and 11% respectively

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06b
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• pp.285-309
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• 1996

Non oxide ceramics such as nitrides of transition metals have shown significant potential for future economic impact, in diverse applications in ceramic, aerospace and electronic industries, as refractory products, abrasives and cutting tools, aircraft components, and semi-conductor substrates amid others. Combustion synthesis has become an attractive alternative to the conventional furnace technology to produce these materials cheaply, faster and at a higher level of purity. However he process os highly exothermic and manifests complex dynamics due to its strongly non-linear nature. In order to develop an understanding of this process and to study the effect of operational parameters on the final outcome, numerical modeling is necessary, which would generated essential knowledge to help scale-up the process. the model is based on a system of parabolic-hyperbolic partial differential equations representing the heat, mass and momentum conservation relations. The model also takes into account structural change due to sintering and volumetric expansion, and their effect on the transport properties of the system. The solutions of these equations exhibit steep moving spatial gradients in the form of reaction fronts, propagating in space with variable velocity, which gives rise to varying time scales. To cope with the possibility of extremely abrupt changes in the values of the solution over very short distances, adaptive mesh techniques can be applied to resolve the high activity regions by ordering grid points in appropriate places. To avoid a control volume formulation of the solution of partial differential equations, a simple orthogonal, adaptive-mesh technique is employed. This involves separate adaptation in the x and y directions. Through simple analysis and numerical examples, the adaptive mesh is shown to give significant increase in accuracy in the computations.

• Land and Housing Review
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• v.11 no.1
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• pp.109-116
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• 2020

This study aims to establish an approach to assess urban flood vulnerability by identifying social characteristics such as the road transportation and the vulnerable groups. Assessment procedures comprise three steps as: (1) composing the assessment criteria to reflect the urban characteristics; (2) calculating the weight; and (3) evaluating the vulnerability. The criteria were adopted by Delphi survey technique. Four criteria as land cover, residents, vulnerable areas, and disaster response were adopted in the current study. To determine the weight set of criteria, subjective and objective methods were combined. The weight set was determined using the combined method which reflects the Delphi method and Entropy analysis. In the process of data-based construction, GIS tools wwere used to extract administrative unit materials such as land cover, road status, and slope. Data on population and other social criteria were collected through the National Statistical Office and the Seoul Metropolitan statistical data. TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) technique, which uses materials from cell units in order to rank the closest distance to the best case and the farthest distance from the worst case by calculating the distances to the area of assessment, was applied to assess. The study area was the Dorimcheon basin, a flood special treatment area of Seoul city. The results from the current study indicates that the established urban flood vulnerability assessment approach is able to predict the inherent vulnerable factors in urban regions and to propose the area of priority control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.212-219
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• 2021

Chemical accidents caused by transport vehicles account for 20% of all chemical accidents every year, but there are difficulties in the accident-response process due to repeated situations where the impact assessment information is unknown. In this study, we developed a calculation table and formula for predicting the range of damage for chlorine and hydrogen fluoride, which have a high domestic usage, high risk of accidents, and high accident frequency in the last 7 years. The calculation table is based on the leakage rate, wind speed, and temperature, and the calculation formula was derived using R software for special situations where it is difficult to apply the calculation table. The calculation table and formula could be used on site by related organizations to obtain important information for decision making, which could help in minimizing damage from chemical accidents, setting separation distances, and deciding to evacuate residents.

• Fisheries and Aquatic Sciences
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• v.22 no.6
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• pp.12.1-12.8
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• 2019

Background: Wild fish populations stock is continuously diminishing in the Indo-Ganges river basin, and the population status of most fishes is unidentified. The identification of the population status and the conservation of commercially important and endemic wild fish populations in this region are crucial for the management. The aim of this paper was to identify the population status of Cirrhinus reba, a promising aquaculture but vulnerable species in the Indo-Ganges river basin in Bangladesh. Methods: C. reba samples were collected from four isolated populations of the Brahmaputra (n = 30), the Padma (33), the Karatoya (31), and the Jamuna Rivers (30) in Bangladesh, and the population status was evaluated using morphometric and landmark comparisons. Data were analyzed with the Kruskal-Wallis test, univariate analysis, discriminant function analysis, and the formation of a dendrogram. Results: Three meristic characters (Pectoral fin rays, caudal fin rays, scale in lateral lines), four morphometric characters (head length, pre-orbital length, post-orbital length, maximum body depth), and truss measurement (4-7) were significantly different among the stocks. The step-wise discriminant function analysis retained 15 variables from morphometric and landmark measurements that significantly differentiated the populations based on the constructed DFI and DFII. Discriminate function analysis also showed that 91.2% of the original groups were classified into their correct samples. The cluster analysis of Euclidean distances placed the Jamuna population in one cluster and the Brahmaputra, the Padma, and the Karatoya populations in the second one. Conclusion : Morphological differences among the stock were probably due to different ancestral origin. This is the first report about population status of C. reba in their natural habitat of the Indian subcontinent. Further genetic studies and the evaluation of environmental impact on C. reba populations in Bangladesh are suggested to support our findings.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.259-266
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• 2019

This paper presents a comparison between experimental measurements and numerical estimations of penetration length of a cement grout injected in discrete joints. In the experiment, a joint was generated by planar acryl plates with a certain separation distance (; aperture) and was designed in such a way to vary the separation distances. Since a cement grout was used, the grout viscosity can be varied by controlling water-cement (W/C) ratios. Throughout these experiments, the influence of joint aperture, cement grout viscosity, and injection rate on a penetration length in a discrete joint was investigated. During the experiments, we also measured the time-dependent variation of grout viscosity due to a hardening process. The time-dependent viscosity was included in our numerical simulations as a function of elapsed time to demonstrate its impact on the estimation of penetration length. In the numerical simulations, Bingham fluid model that has been known to be applicable to a viscous cement material, was employed. We showed that the estimations by the current numerical approach were well comparable to the experimental measurements only in limited conditions of lower injection rates and smaller joint apertures. The difference between two approaches resulted from the facts that material separation (; bleeding) of cement grout, which was noticeable in higher injection rate and there could be a significant surface friction between the grout and joint planes, which are not included in the numerical simulations. Our numerical simulation, meanwhile, could well demonstrate that penetration length can be significantly over-estimated without considering a time-dependency of viscosity in a cement grout.