• The Korean Journal of Pesticide Science
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• v.8 no.4
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• pp.338-346
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• 2004

The methanol extract of Chloranthus japonicus roots effectively controlled the development of rice blast(Magnaporthe grisea), rice sheath blight(Corticium sasaki), tomato pay mold(Btrytis cinerea), tomato late blight(Phytophthora infestans), and wheat leaf rust(Puccinia recondita). From the methanol extract of C. japonicus roots, three antifungal substances were isolated. Their chemical structures were determined to be shizukanols B, C, and D mainly by mass and NMR spectral data. Among the three substances, shizukanol C showed the strongest inhibitory activity against mycelial growth of the plant pathogenic fungi tested; it completely inhibited mycelial growth of M. grisea. Colletotrichum gloeosporioides, and C. acutatum at concentrations of more than $12.5{\mu}g$/ and P. infestans at concentrations of more than $3.13{\mu}g/m\ell$. They also controlled effectively the development of rice blast and wheat leaf rust. On the other hand, they caused phytotoxic symptoms on barley leaves and inhibited the growth of duckweed (Lemna paucicostata) with $EC_{50}$ values of $30.0{\mu}g/m\ell$ for shizukanol B, $49.9{\mu}g/m\ell$ for shizukanol C, and $154{\mu}g/m\ell$ for shizukanol D. In addition, shizukanol C showed an insecticidal activity against brown planthopper (Nilaparavata lugens), peen peach aphid (Myzus persicae), diamond-back moth (Plutella xylostella), and tobacco cutworm (Spodoptera litura) of the 5 arthropod pests tested with mortality values of more than 60% at a concentration of $1,000{\mu}g/m\ell$.

• The Korean Journal of Pesticide Science
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• v.4 no.3
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• pp.19-26
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• 2000

In order to select potent bioactive isolates, 70 Fusarium isolates obtained from soil and 21 plant species were screened by antifungal, insecticidal, herbicidal, and duckweed bioassays after culturing in potato dextrose broth and rice solid media. Eight (11.4%) of the 70 liquid broth cultures showed disease-controlling activities more than 80% against at least one of the 6 plant diseases tested. Fusarium sp. FO-68 isolate exhibited the most potent antifungal activity; it controlled rice blast, wheat leaf rust, and barley powdery mildew with control values more than 95%. Out of 70 solid cultures, 21 (30.0%) controlled at least one plant disease more than 80% and F. equiseti FO-68 isolate showed disease-controlling activities more than 95% against 3 plant diseases such as rice blast, tomato late blight, and wheat leaf rust. As for tile insecticidal activities, 2 liquid and 1 solid cultures showed potent insecticidal activities against pest insects more than 80%, Liquid cultures of F. oxysporum FO-61 and Fusarium sp. FO-80 isolates exhibited insecticidal activities more than 80% against green peach aphid and diamondback moth, respectively. The solid culture of Fusarium sp. FO-510 isolate had 80% insecticidal activity against green peach aphid. However, none of liquid and solid cultures of the 70 Fusarium isolates showed potent herbicidal activities against 10 upland weeds. As the results of duckweed assay, 3 liquid cultures showed 70% growth inhibitory activity at concentrations less than 1.25% of culture supernatants and 9 solid cultures had a potent inhibitory activity against duckweed growth. On the other hand, there was a significant correlation between antifungal activities and herbicidal activities against duckweed of both liquid and solid cultures of tile 70 Fusarium isolates.

• The Korean Journal of Pesticide Science
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• v.5 no.3
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• pp.18-25
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• 2001

Ethanol extracts from 46 plants were tested for their fungicidal activity against six plant diseases consisting of Maynaporthe grisea, Rhizoctonia solani, Botrytis cinerea, Phytophthora infestans, Puccinia recondita, and Erysiphe graminis in the greenhouse studies. Strong activity at 5 and 10 mg/pot was produced from the extracts of Helianthus annuus flowers and Zea mays leaves against P. grisea. In a test with B. cineara, extracts of H. annuus leaves, H. annuus flowers, Chrysanthmum coronarium var. spatiosum, Cucurbita moschata seeds, Lycopersicon esculentum, Z. mays, and Z. mays leaves had strong activities at 5 mg/pot. In a test with P. recondita, strong activity was obtained from the extracts of Capsicum frutescens, C. moschata seeds, H. annuus seeds, L. esculentum, and Malva veticillata at 5 mg/pot. Against E. graminis, extracts of Cucumis sativus, H. annuus seeds, Salanum tuberosum, Z. mays, and Z. mays leaves produced strong activities at 10 mg/pot. All the extracts were ineffective against P. infestans and R. solani. Among seven extracts tested, the extracts of H. annuus leaves and flowers were highly effective against all the strains of B. cinerea resistant to carbendazim, procymidone, and diethofencarb. Furthermore, potent fungicidal activity was produced from the extracts of C. coronarium var. spatiosum and C. moschata seeds against the SSR, SRR, and RSR strains of B. cinerea, and Z. mays and Z. mays leaves against SSR and RSR. Extract of L. esculentum showed very strong activity only against RRS of B. cinerea.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.64-69
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• 1998

New thirty derivatives of 5,6-dihydro-2-trifluoromethyl-1,4-oxathiin carboxanilide as substrate(S) were synthesized and their fungicidal activities in vivo against rice sheath blight(Rhizoctonia solani) and wheat leaf rust(Puccinia recondita) were examined. The structure activity relationships(SAR) between the activities($pI_{50}$) and a physicochemical parameters of substituents(X) at the phenylcarbamoyl group were analyzed using the adaptive regression analysis method. The 3-methoxy, 11, 3-isopropyloxy, 13 and 3-isopropyl substituent, 25 as X on the phenylcarbamoyl group exhibited the most highest fungicidal activity against the two fungi. The fungicidal potency of the (S) against Puccinia recondita was higher than Rhizoctonia solani. In case of Rhizoctonia solani, the molecular hydrophobicity(${\pi}>0$) and resonance effect(R<0) by meta-alkyl substitutents with electron donating were important factors in determining fungicidal activity. And the HOMO energy(HOMO>0), ABSQ, sum of absolute values of the atomic charges on each atom and specific polarizability(Sp.Pol<0) of (S) were significantly influential towards fungicidal activity against Puccinia recondita.. The interaction between (S) and receptor agonist from the based on SAR studies proceeds through charge-control reaction, and conditions to show higher activity has been also discussed.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.399-409
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• 2010

Steel structures are threatened to reduce load-carrying capacity as the cross section is decreased by corrosion. However, there has been no method in definitely evaluating residual load-carrying capacity and the effect of corrosion to the load-carrying capacity of steel. This study evaluated tensile residual load-carrying capacity of corroded steel plates by using tensile tests of specimens, which were selected from the web of temporary structure's main beam. After the surface shapes were measured and tensile tests were examined, the rust of 21 corroded specimens was, first of all, removed using a chemical method. From the tensile test result, which of reference specimens that was picked off at the flange of the same main 13-mm-thick beam and corroded specimens were based, surface geometry and correlation with the reduction of corroded thickness and strain, yield strength or tensile strength was established as constant numbers. Effective thickness of corroded steel with irregular cross sections could be calculated using average residual thickness and standard deviation. The irregular cross sections could be the evaluated tensile strength that is equalized to non-corroded uniform steel's regardless of corrosion. Also, reasonable measuring intervals of residual thickness could be proposed by using this result to apply for executive work.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.432-439
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• 2020

Brake judder has been identified in some operating military units of Korean Light Tactical Vehicles(KLTV) with In-board brake systems to improve braking performance. Severe vibration generated while driving the vehicle may reduce the KLTV's driving stability and further lead to accidents. For the prevention of this, this study analyzes the root cause through the failure analysis on the vehicles with the brake judder identified. Furthermore, the improvement factor was derived by identifying a vibration transmission path by analyzing the vibration transmission mechanism. The study analysis confirmed that the vibration of the frame during braking in the tactical vehicle is a cold judder phenomenon, which is caused by an increase in disk thickness variation due to rust and foreign substances under excessive brake disc's run-out. In addition, it was confirmed that such vibration can be reduced by improving the mounting structure. So, an improvement method for each factor was suggested and its effectiveness was verified by comparison test. Finally, it is expected that the improvement plans derived through this study can be used in the development of a next military vehicle.

• Journal of the Korea Institute of Building Construction
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• v.17 no.6
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• pp.545-557
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• 2017

The study is about the efficient alternative to concrete surface in the field of visual inspection technology for deteriorated infrastructure. By combining industrial drones and deep learning based image analysis techniques with traditional visual inspection and research, we tried to reduce manpowers, time requirements and costs, and to overcome the height and dome structures. On board device mounted on drones is consisting of a high resolution camera for detecting cracks of more than 0.3 mm, a lidar sensor and a embeded image processor module. It was mounted on an industrial drones, took sample images of damage from the site specimen through automatic flight navigation. In addition, the damege parts of the site specimen was used to measure not only the width and length of cracks but white rust also, and tried up compare them with the final image analysis detected results. Using the image analysis techniques, the damages of 54ea sample images were analyzed by the segmentation - feature extraction - decision making process, and extracted the analysis parameters using supervised mode of the deep learning platform. The image analysis of newly added non-supervised 60ea image samples was performed based on the extracted parameters. The result presented in 90.5 % of the damage detection rate.

• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.163-169
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• 2004

Feasibility of using PE sheet laminated CSP(Corrugated steel pipe) to sewers were tested via corrosion and abrasion tests for PE sheet laminated CSP; 1) corrosion test for PE film and PE coated plate, 2) corrosion test for joint of PE sheet laminated CSP, 3) corrosion test for outside of PE sheet laminated CSP, and 4) abrasion test for inside of PE sheet laminated CSP. The results for the corrosion and abrasion tests are as follows. 1. Results for corrosion tests on PE films and zinc coated steel plates that were coated with PE films show that the surfaces of both PE were not changed compared to those of original PE samples. Furthermore, PE films maintained strong adhesion on the steel plates even though they were exposed to sewage and seawater provided cutting planes of the steel plates were treated with molding. But, results for corrosion tests on the spots that were previously cut off by a knife and a cutting planes of the steel plates were treated without molding show that steel plates have been corroded if they were exposed to sewage and seawater. 2. Results for corrosion tests on joints of PE sheet laminated corrugated steel using sewage show that gathering rust was observed at cutting plane of PE sheet laminated corrugated steel after 180 days, but PE film was not flaked off. However, PE film at cutting plane was flaked off when PE sheet laminated corrugated steel was exposed to seawater. Furthermore, flaking process was severely progressed at lockseam points of which the surfaces were not smooth. 3. Results for laying PE sheet laminated corrugated steel under the ground show that the surface of untouched PE film was almost identical to that of original PE film. However, the spots that were previously cut off by a knife and a cutting plane of PE sheet laminated corrugated steel have flaked off. 4. As a result of abrasion tests conducted with PE sheet laminated corrugated steel and sand, brilliance and thickness of PE was not greatly changed under the severe abrasion conditions. Therefore, the durability of PE sheet laminated corrugated steel for abrasion was determined to be good.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.396-400
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• 2006

In the preliminary experiment, the factors(soil moisture content, type of organic fertilizers, wound of ginseng, and concentration of rusty-root causing bacteria) inducing the rusty-root of ginseng were investigated. The Hue values were measured for the degree of rustiness affected by the factors. The rustiness was severe on the wounded-ginseng and on the ginseng inoculated with Agrobacterium tumefaciens (CG20126). The Hue values of the control, the non-wounded ginseng inoculated with CG20126, the wounded-ginseng, and the wounded-ginseng inoculated with CG20126 were 113.3, 108.1, 85.8, and 57.5, respectively. The Hue value of the horticulture bed-soil was 56.8 whereas the value of the paddy bed-soil counterpart was 64.7. The Hue values on the ginseng roots grown in the soil containing 10%, 20%, 50%, and 70% of moisture, were 96.2, 85.9, 78.0, and 75.7, respectively. The organic fertilizer increased the rustiness of ginseng and the range of Hue values was 35.2-27.8. The increased concentrations of A. tumefaciens CG20126 increased the rustiness of ginseng. The concentration of A. tumefaciens CG20126 at $10^{2},\;10^{4},\;10^{6},\;and\;10^{8}cells/m{\ell}$ resulted in the Hue values of 62.8, 63.3, 55.6, and 48.8, respectively.

• The Plant Pathology Journal
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• v.33 no.5
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• pp.488-498
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• 2017

The aim of this study was to identify volatile and agardiffusible antifungal metabolites produced by Bacillus sp. G341 with strong antifungal activity against various phytopathogenic fungi. Strain G341 isolated from four-year-old roots of Korean ginseng with rot symptoms was identified as Bacillus velezensis based on 16S rDNA and gyrA sequences. Strain G341 inhibited mycelial growth of all phytopathogenic fungi tested. In vivo experiment results revealed that n-butanol extract of fermentation broth effectively controlled the development of rice sheath blight, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew, and red pepper anthracnose. Two antifungal compounds were isolated from strain G341 and identified as bacillomycin L and fengycin A by MS/MS analysis. Moreover, volatile compounds emitted from strain G341 were found to be able to inhibit mycelial growth of various phytopathogenic fungi. Based on volatile compound profiles of strain G341 obtained through headspace collection and analysis on GC-MS, dimethylsulfoxide, 1-butanol, and 3-hydroxy-2-butanone (acetoin) were identified. Taken together, these results suggest that B. valezensis G341 can be used as a biocontrol agent for various plant diseases caused by phytopathogenic fungi.