• Journal of the Korean Wood Science and Technology
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• 제22권1호
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• pp.20-27
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• 1994

Water repellent preservative (WRP) treated and untreated, small-sized specimens prepared from semiwater resistant, water resistant, and tegofilm-overlaid plywood were exposed to outdoor weathering for one year. Exterior durability of specimens was evaluated on the basis of changes in dynamic modulus of elasticity, degree of delamination, modulus of elasticity, modulus of rupture, and glueline shear strength. Among untreated specimens, tegofilm-overlaid plywood showed the best outdoor durability, and durability between semiwater resistant and water resistant plywood was similar. Although WRP treatment increased the durability of all types of plywoods, the effect of treatment on the increase in durability for semi water resistant plywood was not distinct. Accordingly, it can be concluded that semi water resistant plywood, which is used for temporary construction such as concrete formwork in our country, can not be inadequate for exterior use, regardless of WRP treatment. The bending strength and glueline shear strength of untreated water resistant plywood measured after weathering for one year did not exceed the minimum value specified by Korean Standard (KS), thereby the outdoor use of water resistant plywood was not desirable without WRP treatment. Exterior durability between treated water resistant plywood and untreated tegofilm-overlaid plywood was very similar. This result suggests that if an exposed plywood surface is treated with WRP regularly water resistant plywood can be used for temporary construction. This suggestion, however, needs to be investigated. In summary, semiwater resistant plywood cannot be used for temporay construction regardless of WRP treatment. Water resistant plywood can be used only with WRP treatment. Comparing the cost of tegofilm-overlaid plywood to costs of water resistant plywood and WRP treatment, however, it can be concluded that use of tegofilm-overlaid plywood for temporay constrution is strongly suggested from the point of view of both outdoor durability and costs.

• 한국자원식물학회지
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• 제31권6호
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• pp.719-724
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• 2018

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for a number of infections in humans that are difficult to treat, and as a result, is a substantial contributor to morbidity and mortality. In the present study, in search of natural products capable of inhibiting this multidrug-resistant bacterium, we investigated the antimicrobial activity of Lysimachia clethroides Duby root. The antibacterial activities of EtOH extract of Lysimachia clethroides Duby root and its n-hexane, EtOAc, n-BuOH and water fractions were evaluated against 15 strains of methicillin-resistant staphylococcus aureus (MRSA) and 1 standard methicillin-susceptible S. aureus (MSSA) strain by using the minimal inhibitory concentrations (MICs) assay, colorimetric assay using MTT test, checkerboard dilution test. Antimicrobial activity of n-hexane fraction of Lysimachia clethroides Duby root was remarkable. Against the 16 strains, the minimum inhibitory concentrations (MICs) were in the range of $31.25-62.5{\mu}g/ml$ and FICI values for n-hexane fraction of Lysimachia clethroides Duby root+AM and n-hexane fraction of Lysimachia clethroides Duby root+OX were checkerboard method performed using the MRSA, MSSA and one clinical isolate strains via MICI 0.12-1 and 0.25-0.75, showing the increase of synergistic effect. When combined together, these antibiotic effects were dramatically increased. These effective combinations could be new promising agents in the management of MRSA.

• Journal of Ginseng Research
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• 제34권4호
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• pp.274-281
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• 2010

This experiment was conducted to examine ginseng lines resistant and susceptible to high-temperature injury and to investigate characteristics of the selected lines: leaf burning phenomenon, chlorophyll content, quantum yield, and maximum light interception rate. The leaf burning phenomenon incidence rates of the resistant lines Yunpoong, high-temperature injury resistance (HTIR)1, HTIR2, and HTIR3 were low: 5.8%, 3.6%, 4.0%, and 1.9%, respectively. Resistance of the susceptible lines Chunpoong, high-temperature injury susceptible (HTIS)1, and HTIS2 was high: 58.5%, 23.2%, and 21.7%, respectively. The chlorophyll content (SPAD value) of the resistant lines Yunpoong, HTIR1, HTIR2, and HTIR3, which were exposed to high temperatures and intense light, remained as high at 24.8, 27.9, 24.9, and 30.6, respectively, but that of the susceptible lines Chunpoong, HTIS1, and HTIS2 was low at 21.0, 21.1, and 20.1, respectively. During the summer season, the quantum yield of the resistant lines (Yunpoong, HTIR1, HTIR2, and HTIR3) changed little, but that of the susceptible lines (Chunpoong, HTIS1, and HTIS2) changed dramatically. The maximum light interception rate (Fm/Fv value) for the resistant lines (Yunpoong, HTIR1, HTIR2, and HTIR3) was as high as 0.848, 0.794, 0.805, and 0.813, respectively, while that of the susceptible lines (Chunpoong, HTIS1, and HTIS2) was 0.678, 0.642, and 0.717, respectively. Based on these results, the high-temperature injury-resistant lines seemed to be less susceptible to high light, even at high temperatures. Future studies on red ginseng quality and its active ingredients in resistant ginseng lines and field experimentation will be conducted to verify the potential of the resistant lines.

• 한국자원식물학회지
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• 제29권6호
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• pp.699-703
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• 2016

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious clinical and an urgent problem worldwide. Few new drugs are available against MRSA, because MRSA has the ability to acquire resistance to most antibiotics, which consequently increases the cost of medication. In the present study, the antibacterial activity of Hydnocarpi Semen was investigated. The most effective method is to develop antibiotics from the natural products without having any toxic or side effects. Therefore, there is a need to develop alternative antibacterial drugs for the treatment of infectious diseases. Five Clinical isolates (MRSA) were obtained from five different patients at Wonkwang University Hospital (Iksan, South Korea). The Other 2 strains were ATCC 33591 (Methicillin-resistant strain) and ATCC 25923 (Methicillin-susceptible strain). Antibacterial activity (Minimal Inhibitory Concentrations, MICs) was determined by broth dilution method, disk diffusion method, MTT test, and checkerboard dilution test. Antibacterial activity of n-hexane fraction was remarkable, and had a MICs ranging from $31.25-125{\mu}g/m{\ell}$. FICI values for HFH+AM and HFH+OX were 0.13-0.19 and 0.04-0.29, showing the increase of synergistic effect. When combined together, these antibacterial effects were dramatically increased.

• Plant Resources
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• 제5권3호
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• pp.169-175
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• 2002

The soybean cyst nematode (Heterodera glycines Inchinoe; SCN) is a devastating pest of soybean and is responsible for significant losses in yield. The use of resistant cultivars is the effective method to reduce or eliminate SCN damage. The objective of this research is to identify AFLP markers linked to the SCN resistant genes. Bulked genomic DNA was made from resistant and susceptible genotypes to SCN and a total of 19 primer combinations were used. About 31 fragments were detected per primer combination. The banding patterns were readily distinguished in resistant and susceptible bulked genotypes. Polymorphic fragments were detected between resistant and susceptible bulked genotypes in the primer combination of CGT/GGC, CAG/GTG and CTC/GAG. In primer combinations of CGT/GGC and CAG/GTG, bulked resistant genotype produced a polymorphic bands. However, in primer of CTC/GAG, bulked susceptible genotype produced a polymorphic fragments. Three AFLP markers identified as a polymorphic fragments between bulked genomic DNA were mapped in 85 F2 population. Among them, only two markers, CGT/GGC and CTC/GAG, was linked and was mapped. Broad application of AFLP marker would be possible for improving resistant cultivars to SCN.

• 한국자원식물학회지
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• 제32권6호
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• pp.743-751
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• 2019

Sclerotinia rot, caused by Sclerotinia sclerotiorum, is a devastating disease that poses a serious threat to perilla production in Korea. Identifying effective sources of resistance offers long term prospects for improving management of this disease. Screening disease resistant genetic resources is important for development of disease-resistant, new cultivars and conduct related research. In the present study, perilla germplasm were screened in vitro against S. sclerotiorum using detached leaf method. Among 544 perilla accessions, two were highly resistant (IT226504, IT226533), five were resistant (IT226561, IT226532, IT226526, IT226441, and IT226589), five were moderately resistant (IT226525, IT226640, IT226568, IT220624, and IT178655), 16 were moderately susceptible, 31 were susceptible, and 485 were highly susceptible. The resistant accessions in this study could serve as resistance donor in the breeding of Sclerotinia rot resistance or subjected to selection procedure of varietal development for direct use by breeders, farmers, researchers, and end consumers.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.15-22
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• 2008

Four series (S, M, R, and W) of Alternaria longipes isolates were obtained based on consecutive selection with Dimethachlon (Dim) and ultraviolet irradiation. These isolates were then characterized according to their tolerance to Dim, sensitivity to osmotic stress, and phenotypic properties. All the selected Dim-resistant isolates showed a higher osmosensitivity than the parental strains, and the last generation was more resistant than the first generation in the M, R, and W series. In addition, the changes in the Dim resistance and osmotic sensitivity were not found to be directly correlated, and no distinct morphologic characteristics were found among the resistant and sensitive isolates, with the exception of the resistant isolate K-11. Thus, to investigate the molecular basis of the fungicide resistance, a group III two-component histidine kinase (HK) gene, AlHK1, was cloned from nineteen A. longipes isolates. AlHK1p was found to be comprised of a six 92-amino-acid repeat domain (AARD), HK domain, and response regulator domain, similar to the Os-1p from Neurospora crassa. A comparison of the nucleotide sequences of the AlHK1 gene from the Dim-sensitive and -resistant isolates revealed that all the resistant isolates contained a single-point mutation in the AARD of AlHK1p, with the exception of isolate K-11, where the AlHK1p contained a deletion of 107 amino acids. Moreover, the AlHK1p mutations in the isolates of each respective series involved the same amino acid substitution at the same site, although the resistance levels differed significantly in each series. Therefore, these findings suggested that a mutation in the AARD of AlHK1p was not the sole factor responsible for A. longipes resistance to dicarboximide fungicides.

• 한국세라믹학회지
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• 제52권4호
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• pp.253-263
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• 2015

Ordinary Portland cement is a widely favored construction material because of its good strength and durability and its reasonable price; however, spalling behaviour during fire exposure can be a serious risk that can lead to strength degradation or collapse of a building. Geopolymers, which can be synthesized by mixing aluminosilicate source materials such as metakaolin and fly ash, and alkali activators, are resistant to fire. Because the chemical composition of geopolymers controls the properties of the geopolyers, geopolymers with various Si:Al ratios were synthesized and evaluated as fire resistant construction materials. Rejected fly ash generated from a power plant was quantitatively analyzed and mixed with alkali activators to produce geopolymers having Si:Al ratios of 1.5, 2.0, and 3.5. Compressive strength of the geopolymers was measured at 28 days before and after heating at $900^{\circ}C$. Geopolymers having an Si:Al ratio of 1.5 presented the best fire resistance, with a 44% increase of strength from 29 MPa to 41 MPa after heating. This material also showed the least expansion-shrinkage characteristics. Geopolymer mortar developed no spalling and presented more than a 2 h fire resistance rating at $1,050^{\circ}C$ during the fire testing, with a cold side temperature of $74^{\circ}C$. Geopolymers have high potential as a fire resistant construction material in terms of their increased strength after exposure to fire.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.474-478
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• 2004

Based on the recent laboratory experiments (Kim et al. 2004), comparisons of caisson sliding distance are made between the computations and experiments. The time history model of wave force, which is proposed by Tanimoto et al. (1996), is modified in the standing wave part of horizontal and uplift wave forces because of the overestimation of the time history model. The comparison between experimental and computational sliding distance has showed that the caisson tilting increases the resistant force to the horizontal sliding. Therefore, a titling resistant force, which is caused by caisson tilting, is introduced into computation of sliding distance.

• 한국육종학회지
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• 제41권2호
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• pp.73-83
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• 2009

To investigate genes related to vernalization and cold- resistance in barley (Hordeum vulgare L. cv. Nagaoka), differentially expressed genes were identified from cold-resistant barley leaves with suppression subtractive hybridization (SSH) and Northern blot analyses. The nucleotide and the deduced amino acid sequences of the putative gene products were compared. The bvrn-7 showed high homology(84%) with gene related to vernalization, and the bvrn-3, bvrn-12, bvrn-28, bvrn-29 and bvrn-36 related to cold-resistant genes had high identity of 88~98% with low temperature-induced genes. The results indicate that the 6 genes were closely related to vernalization and cold-resistance during low temperature treatment.