• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.153-160
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• 2010

This study aims to obtain technical data for improvement of utilization of Blast Furnace Slag(BFS), recycled aggregate in the future by complementing fundamental problems of BFS such as manifestation of initial strength and excessive alkali quantity as well as weakness of recycled fine aggregate through manufacturing of recycled fine aggregate mortar using BFS. The recycled aggregate includes the cement paste hardened as the surface and the type of the aggregate, which contains plenty of calcium hydroxide($Ca(OH)_2$) as well as the unhydrated cement. Accordingly, the objectives of this study are to inspect the manufacturing the recycled fine aggregate mortar used with blast furnace slag, to consider the effects of the recycled aggregate on the strength development of ground granulated blast furnace slag, and then to acquire the technical data to take into consideration the further usages of the recycled aggregate and blast furnace slag. In eluted ions from recycled aggregate, it showed that there were natrium($Na^+$) and kalium($K^+$), expected to be flown out of unhydrated cement, as well as calcium hydroxide($Ca(OH)_2$). Application of this water to mix cement mortar with ground granulated blast furnace slag was observed to expedite hydration as calcium hydroxide($Ca(OH)_2$) and unhydrated cement component were expressed to give stimuli effects on ground granulated blast furnace slag. The results of the experiment show that the recycled aggregate mixed with blast furnace slag has comparatively higher hydration activity in 7 day than the mortar not mixed with one in 3 day mortar does, causing the calcium hydroxide in the recycled fine aggregate to work on as a stimulus to the hydration of ground granulated blast furnace slag.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.245-257
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• 2023

The representative crop in the Republic of Korea, rice, is cultivated over extensive areas every year, which resulting in reduced resistance to pests and diseases. One of the major rice diseases, rice blast disease, can lead to a significant decrease in yields when it occurs on a large scale, necessitating early detection and effective control of rice blast disease. Drone-based crop monitoring techniques are valuable for detecting abnormal growth, but frequent image capture for potential rice blast disease occurrences can consume significant labor and resources. The purpose of this study is to early detect rice blast disease using remote sensing data, such as drone and satellite images, along with weather data. Satellite images was helpful in identifying rice cultivation fields. Effective detection of paddy fields was achieved by utilizing vegetation and water indices. Subsequently, air temperature, relative humidity, and number of rainy days were used to calculate the risk of rice blast disease occurrence. An increase in the risk of disease occurrence implies a higher likelihood of disease development, and drone measurements perform at this time. Spectral reflectance changes in the red and near-infrared wavelength regions were observed at the locations where rice blast disease occurred. Clusters with low vegetation index values were observed at locations where rice blast disease occurred, and the time series data for drone images allowed for tracking the spread of the disease from these points. Finally, drone images captured before harvesting was used to generate spatial information on the incidence of rice blast disease in each field.

• Journal of Korean Society of Steel Construction
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• v.20 no.5
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• pp.583-590
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• 2008

Blasting has been applied in newly-built steel structures for cleaning forged surfaces and increasing the adhesive property of applied painting systems. However, the effect of the blast cleaning on fatigue behavior of welded joints is not clear. In this paper, fatigue tests were carried out on out-of-plane gusset welded joints and the effect of the blast cleaning on the fatigue behavior was studied. The curvature radius at the weld toe of the surface-treated specimens by using the blast method is larger than that of as-welded specimens. By the blast cleaning compressive residual stresses were induced into weld toes. The experimental results showed that the fatigue life of surface-treated specimens is longer than that of as-welded specimens, even though the fatigue life of surface-treated specimens and that of as-welded specimens are not clearly different in the high stress range. About a 160% increase in fatigue limit could be realized by using blast cleaning.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.629-636
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• 2011

It has been suggested that buildings designed for strong ground motions will also have improved resistance to air blast loads. As an initial attempt to quantify this behavior, the responses of a ten story steel building, designed for the 1994 building code, with lateral resistance provided by perimeter moment frames, is considered. An analytical model of the building is developed and the magnitude and distribution of blast loads on the structure are estimated using available computer software that is based on empirical methods. To obtain the relationship between pressure, time duration, and standoff distance, these programs are used to obtain an accurate model of the air blast loading. A hemispherical surface burst for various explosive weights and standoff distances is considered for generating the air blast loading and determining the structural response. Linear and nonlinear analyses are conducted for these loadings. Air blast demands on the structure are compared to current seismic guidelines. These studies present the displacement responses, story drifts, demand/capacity ratio and inelastic demands for this structure.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.2
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• pp.76-82
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• 1981

A water culture experiment was carried out to elucidate the relationship between the nutritional conditions emphasized on $SiO_2$ of rice plant with the growth stages and rice blast incidence. Two rice cultivars, Milyang 23 and Nakdongbyeo were tested under the two Nitrogen levels and $SiO_2$ applications at the different growth stages. The results obtained were as follows. 1. By silicate application, the incidence of rice blast disease was remarkably reduced possibly due to increase of silicate and decrease of nitrogen contents in rice plant. 2. Silicate application at the late growth stage also reduced infected ratio of neck blast. 3. The effect of silicate on reducing the incidence of rice blast disease was clearer in neck blast than in leaf blast.

• Resources Recycling
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• v.15 no.2 s.70
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• pp.10-17
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• 2006

The purpose of this study was to evaluate the effects of blast-furnace slag on strength development and durability of latex-modified concrete (LMC) and ordinary portland cement concrete as slag contents. Main experimental variables were performed latex contents (0%, 10%, 15%) and slag contents (0%, 30%). The compressive and flexural strengths, chloride-ion rapid permeability and chemical attacks resistance were measured to analyze the characteristic of the developed LMC and BS-LMC(latex-modified concrete added blast-furnace slag) on hardened concrete. The test results showed that compressive and flexural strength of BS-LMC increased as the slag contents increased from 0% to 30% at the long term of curing. It considers blast furnace slag used when latex content was up to 10%. The permeability resistance of BS-LMC(latex 10%, blast 30%) was extremely good at the curing time 90 days. Also. the effects of added blast furnace slag on OPC and LMC were increased on the permeability and chemical attacks resistance.

• Korean Journal of Plant Resources
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• v.29 no.6
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• pp.658-669
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• 2016

Rice blast, caused by a fungus Magnaporthe oryzae, is one of the most devastating diseases of rice worldwide. Analyzing the valuable genetic resources is important in making progress towards blast resistance. Molecular screening of major rice blast resistance (R) genes was determined in 2,509 accessions of rice germplasm from different geographic regions of Asia and Europe using PCR based markers which showed linkage to twelve major blast R genes, Pik-p, Pi39, Pit, Pik-m, Pi-d(t)2, Pii, Pib, Pik, Pita, Pita/Pita-2, Pi5, and Piz-t. Out of 2,509 accessions, only two accessions had maximum nine blast resistance genes followed by eighteen accessions each with eight R genes. The polygenic combination of three genes was possessed by maximum number of accessions (824), while among others 48 accessions possessed seven genes, 119 accessions had six genes, 267 accessions had five genes, 487 accessions had four genes, 646 accessions had two genes, and 98 accessions had single R gene. The Pik-p gene appeared to be omnipresent and was detected in all germplasm. Furthermore, principal component analysis (PCA) indicated that Pita, Pita/Pita-2, Pi-d(t)2, Pib and Pit were the major genes responsible for resistance in the germplasm. The present investigation revealed that a set of 68 elite germplasm accessions would have a competitive edge over the current resistance donors being utilized in the breeding programs. Overall, these results might be useful to identify and incorporate the resistance genes from germplasm into elite cultivars through marker assisted selection in rice breeding.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.182-182
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• 2017

The objective of this research was to determine controlling effects on rice blast (Pyricularia oryzae) in rice plants by using plant extracts from different extraction methods (water, boiling water, fermentation, and ethanol) from 38 agricultural materials of traditional agriculture. Rice blast was completely suppressed by 3% ethanol extracts in Rheum palmatum roots, and suppressed 97% and 77% by 10% ethanol extracts in onion bulb and pine tree leaves, respectively in a laboratory test. However, other agricultural materials showed low effect on suppression of rice blast. Additionally, in a seedling test, rice injury of two cultivars (Ilmibyeo and Hopyoungbyeo) against rice blast was reduced 40-71%, 29-63%, and 23-63% by 5 and 10% ethanol extracts in Rheum palmatum roots, onion bulb, and pine tree leaves, respectively, compared with non-treated controls. Rice injury of two cultivars (Ilmibyeo and Hopyoungbyeo) against rice blast was reduced by 21-55%, 23-46%, and 5-39% in response to Rheum palmatum roots, onion bulb, and pine tree leaf applications at 100, 200 and $400g/m^2$ at 0 day after seeding, respectively, compared with non-treated controls. Rice plants did not show any leaf injuries and growth reduction after treatments of the Rheum palmatum roots, onion bulb, and pine tree leaf extracts or soil application. Thus, the above materials may be used for controlling rice blast in organically produced rice fields.

• Architectural research
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• v.15 no.3
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• pp.151-158
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• 2013

Offshore oil and gas process plants are exposed to hazardous accidents such as explosion and fire, so that the structural components should resist such accidental loads. Given the possibilities of thousands of different scenarios for the occurrence of an accidental hazard, the best way to predict a reasonable size of a specific accidental load would be the employment of a probabilistic approach. Having the fact that a specific procedure for probabilistic accidental hazard analysis has not yet been established especially for explosion and fire hazards, it is widely accepted that engineers usually take simple and conservative figures in assuming uncertainties inherent in the procedure, resulting either in underestimation or more likely in overestimation in the topside structural design for offshore plants. The variation in the results of a probabilistic approach is determined by the assumptions accepted in the procedures of explosion probability computation, explosion analysis, and structural analysis. A design overpressure load for a sample offshore plant is determined according to the proposed probabilistic approach in this study. CFD analysis results using a Flame Acceleration Simulator, FLACS_v9.1, are utilized to create an overpressure hazard curve. Moreover, the negative impulse and frequency contents of a blast wave are considerably influencing structural responses, but those are completely ignored in a widely used triangular form of blast wave. An idealistic blast wave profile deploying both negative and positive pulses is proposed in this study. A topside process module and piperack with blast wall are 3D FE modeled for structural analysis using LS-DYNA. Three different types of blast wave profiles are applied, two of typical triangular forms having different impulse and the proposed load profile. In conclusion, it is found that a typical triangular blast load leads to overestimation in structural design.

• Resources Recycling
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• v.17 no.5
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• pp.11-18
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• 2008

The purpose of this study was to evaluate the effects of blast-furnace slag on chemical attack and carbonation of latex-modified concrete (LMC) and ordinary portland cement concrete as slag contents. Main experimental variables were performed latex contents (0%, 15%) and slag contents (0%, 30%, 50%). The compressive strengths, chemical attacks resistance and carbonation depth were measured to analyze the characteristic of the developed LMC and BS-LMC(latex-modified concrete added blast-furnace slag) on hardened concrete. The test results showed that compressive strength of BS-LMC with blast-furnace slag content 30% was quite similar to it of OPC without slag content. The structural quality deterioration was concerned when blast slag content was up to 50%. However, carbonation restraint of BS-LMC with blast-furnace slag 30% was bigger then that of opc. Also, the effects of added latex on OPC and BS-LMC were increased on the carbonation restraint and chemical attacks resistance.