• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.52-59
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• 2014

This study examines the compressive strength, elastic modulus and splitting tensile strength of geopolymer concrete in order to evaluate its mechanical characteristics according to the admixing of fly ash and blast furnace slag. Moreover, identical tests are also conducted considering the amount of powder, the mixing ratio of alkali activator and the mixing ratio of silica fume for further comparative analysis considering various variables. The comparison with the formulae specified in Korean and overseas codes reveal that a mixing ratio of 18% is adequate for the alkali activator and that a replacement ratio of 5% by silica fume is recommended for silica fume. The elastic modulus of the geopolymer concrete appears to increase slightly with the increase of the compressive strength per variable and age and to be smaller than the values predicted by the formulae specified in Korean and overseas codes. In addition, the examination of the stress-strain curves shows that the geopolymer concrete exhibits ductile behavior compared to the conventional OPC. In view of the splitting tensile strength, high strength is observed for a powder content of $400kg/m^3$ and a replacement ratio of 18% by silica fume. The resulting ratio of the compressive strength to the splitting tensile strength is seen to range between 8.7 and 10.2%.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.629-638
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• 2009

In this paper, the existing formulas of the step-by-step method were generalized for effective estimation of responses of complicated composite sections due to long-term deformation of concrete. The initial transformed section properties of the composite section were derived from material and section properties of concrete section and sections which confine the longterm deformation of concrete. The transformed section properties at each step were derived from the effective modulus of elasticity considered the creep coefficient variation. Improved formulas of the step-by-step method for generalized responses were derived by introducing 5 generalized parameters. The formulas can be more simplified by applying constant increment of creep coefficient at each step. The constant increment of creep coefficient at each step can also reduce computing time and make equal computing error of each step. The generalized responses for axial elastic strain of concrete section were most sensitive to the area rate of concrete section, and the ratio of the second moment of the confining section area was more sensitive than that of the concrete section. Those for elastic curvature of concrete section were most sensitive to the ratio of the second moment of concrete section area.

• Journal of Microbiology and Biotechnology
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• v.17 no.4
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• pp.638-643
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• 2007

The full encoding sequence for human type II hexokinase (HXK II) was cloned into the E. coli expression vector pET 21b and expressed as a C-terminally hexahistidine-tagged protein in the BL2l (DE3) strain. The IPTG-induced HXK II approximately accounted for 17% of the total E. coli proteins, and 81% of HXK $II_{6{\times}His}$ existed in inclusion bodies. To improve the production of soluble recombinant HXK II protein, in the functionally active form, we used low temperature, and the osmotic stress expression method. When expressed at $18^{\circ}C$, about 83% of HXK $II_{6{\times}His}$ existed in the soluble fraction, which amounted to a 4.1-fold yield over that expressed at $37^{\circ}C$. The soluble form of HXK $II_{6{\times}His}$ was also highly produced in the presence of 1M sorbitol under the standard condition $(37^{\circ}C)$, which indicated that temperature downshift and low water potentials were required to improve the yield of active recombinant HXK II protein. The expressed protein was purified by metal chelate affinity chromatography performed in an IDA Excellose column charged with $Ni^{2+}$ ions, resulting in about 40mg recombinant HXK II protein obtained with purity over 89% from 51 of E. coli culture. The identity of HXK $II_{6{\times}His}$ was confirmed by Western blotting analysis. Taken together, using the stress-governed expression described in this study, human active HXK II can be purified in sufficient amounts for biochemical and biomedical studies.

• Journal of Microbiology and Biotechnology
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• v.22 no.4
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• pp.555-562
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• 2012

PCR was performed to analyze the ${\beta}$-lactamase genes carried by ampicillin-resistant Vibrio spp. strains isolated from marine environments in Korea between 2006 and 2009. All 36 strains tested showed negative results in PCR with the primers designed from the nucleotide sequences of various known ${\beta}$-lactamase genes. This prompted us to screen new ${\beta}$-lactamase genes. A novel ${\beta}$-lactamase gene was cloned from Vibrio alginolyticus KV3 isolated from the aquaculture water of Geoje Island of Korea. The determined nucleotide sequence (VAK-3 ${\beta}$-lactamase) revealed an open reading frame (ORF) of 852 bp, encoding a protein of 283 amino acids (aa), which displayed low homology to any other ${\beta}$-lactamase genes reported in public databases. The deduced 283 aa sequence of VAK-3, consisting of a 19 aa signal peptide and a 264 aa mature protein, contained highly conserved peptide segments specific to class A ${\beta}$-lactamases including the specific amino acid residues STFK (62-65), SDN (122-124), E (158), and RTG (226-228). Results from PCR performed with primers specific to the VAK-3 ${\beta}$-lactamase gene identified 3 of the 36 isolated strains as V. alginolyticus, Vibrio cholerae, and Photobacterium damselae subsp. damselae, indicating the utilization of various ${\beta}$-lactamase genes including unidentified ones in ampicillin-resistant Vibrio spp. strains from the marine environment. In a mating experiment, none of the isolates transfered the VAK-3 ${\beta}$-lactamase gene to the Escherichia coli recipient. This lack of mobility, and the presence of a chromosomal acyl-CoA flanking sequence upstream of the VAK-3 ${\beta}$-lactamase gene, led to the assumption that the location of this new ${\beta}$-lactamase gene was in the chromosome, rather than the mobile plasmid. Antibiotic susceptibility of VAK-3 ${\beta}$-lactamase was indicated by elevated levels of resistance to penicillins, but not to cephalosporins in the wild type and E. coli harboring recombinant plasmid pKV-3, compared with those of the host strain alone. Phylogenetic analysis showed that VAK-3 ${\beta}$-lactamase is a new and separate member of class A ${\beta}$-lactamases.

• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.372-378
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• 2013

An alginate-degrading bacterium, identified as Shewanella oneidensis PKA 1008 by 16S ribosomal RNA sequence analysis, was isolated from the green alga Ulva pertusa. Optimal conditions for the alginate-degrading ability of its crude enzyme were then determined. The optimal culture conditions for the growth of S. oneidensis PKA 1008 were pH 9, 2% NaCl, $30^{\circ}C$, and 24 hours incubation time. The crude enzyme produced by S. oneidensis PKA 1008 showed the highest alginate-degrading activity at pH 9, $30^{\circ}C$ and produced 1.001 g of reducing sugar per liter in 3.5% (w/v) sodium alginate for 1 hour.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.33-43
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• 2013

A bacterium producing a fibrinolytic enzyme was isolated from Cheonggukjang. The bacterium was identified as a strain of Bacillus amyloliquefaciens by 16S rDNA analysis and designated as B. amyloliquefaciens HC188. The optimum culture medium appeared to be one containing 0.5% (w/v) maltose and 0.5% (w/v) soytone. Bacterial growth in the optimal medium at $37^{\circ}C$ reached the stationary phase after 27 h of incubation and the fibrinolytic enzyme showed optimum activity at 24 h. The enzyme was purified by 20-80% ammonium sulfate precipitation, CM Sepharose fast flow ion exchange chromatography, and Sephacryl S-200HR column chromatography. Its specific activity was 38359.3 units/mg protein and the yield was 5.5% of the total activity of the crude extracts. The molecular weight was 24.7 kDa and the amino acids of the N-terminal sequence were AQSVPYGVSQIKAPA. The fibrinolytic enzyme activity had an optimum temperature of $40^{\circ}C$ and an optimum pH of 8.0, and the enzyme was stable in the ranges $20-40^{\circ}C$ and pH 6.0-8.0. Enzyme activity was increased by $Ca^{2+}$ and $Co^{2+}$ but inhibited by $Cu^{2+}$, EDTA, and PMSF. It is suggested that the purified enzyme is a metallo-serine protease.

• Microbiology and Biotechnology Letters
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• v.34 no.3
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• pp.244-249
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• 2006

In order to select the best strains to have the feasibility of Cheonghju brewing, 10 wild type yeast strains from 300 different types of Nuruk were investigated on their ethanol resistance, resistance to glucose and flocculation. The amounts of alcohol, organic acids, and volatile compounds, Brix, pH were also examined for the alcoholic beverages made with the 10 selected strains. Almost all strains showed alcohol production activities in the medium containing 18%(v/v) ethanol and 29%(w/v) glucose. The strains 90-2 showed a higher flocculation activity than other strains. Strains 54-3, 90-2 and 91-5 produced more alcohol than control strain (7.42%(w/w)) when fermented with wild type yeast strains. In addition, alcoholic beverages containing low acetic acid also showed low levels of total acidity. GC/MS analysis of the product showed 4 alcohols, 11 esters and 1 acid as volatile compounds. Selected strains were tentatively identified as Phichia sydowiorum (91-5), Zygosaccharomyces cidri (192-2 and 271-4), and as Saccharomyces cerevisiae (18-2, 54-3, 90-2, 91-2, 98-2, 99-5 and 272-7) by BIIOLOG method.

• Research in Plant Disease
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• v.23 no.1
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• pp.60-64
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• 2017

Leaves of twenties radish (Raphanus sativus L.) inbred lines were mechanically inoculated with Turnip mosaic virus (TuMV) strain HY to evaluate TuMV resistance of the radish inbred lines. The inoculated radish plants were incubated at $22^{\circ}C{\pm}3^{\circ}C$ and resistance assessment was examined using symptom development for 4 weeks. Based on the reactions of differential radish inbred lines, 16 radish lines were produced mild mosaic, mottling, mosaic and severe mosaic symptoms by TuMV infection. These results were confirmed by RT-PCR analysis of TuMV coat protein gene, suggesting that TuMV is responsible for the disease symptoms. Four resistant radish lines did not induce systemic mosaic symptoms on upper leaves and chlorosis in stem tissues for 4 weeks, showing they were symptomless by 8 weeks. Further examination of TuMV infection in the 4 radish lines showed no TuMV infection in all systemic leaves. These results suggest that the 4 radish lines are highly resistant to TuMV.

• International Journal of Highway Engineering
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• v.8 no.2 s.28
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• pp.1-12
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• 2006

An existing Steel pipe, Cast iron pipe and Concrete pipe is can not escaped from aging, specially Metal tube is causing many problems that the quality of water worse is concerned about many rust and mike efficient use of preservation of water. The use of Glassfiber Reinforced Plastic Pipe(GRP PIPE) should be one of the possible scheme to get over these problems. The GRP PIPE has an excellent resistance power and the life is lasting from 50 to 100 years roughly. It's to be useful as a result of high durability and a good construction work also it is a light weight therefore can be expected to short the time of construction and man power. In this research, to executed the small-scaled model test, in-situ model test using CLSM of in-situ soil and to evaluated the stress - strain of the pipe also try to estimated how useful is. From the model test in laboratory, the vertical and horizontal deformation of the GRP PIPE measured in six instance using 200mm and 300mm in diameters. The value of experimentation, theory, analysis got the same results of the test, but the vertical and horizontal deformation gauged in small and the earth pressure was almost zero using CLSM of in-situ soil..

• Korean Journal of Environmental Biology
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• v.34 no.1
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• pp.56-62
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• 2016

Pest population density models are very important to monitor the initial occurrence and to understand the continuous fluctuation pattern of pest in pest management. This is one of the major issues in agriculture because these predictions make pesticides more effective and environmental impact of pesticides less. In this study, we combined and predicted the mortality change of pest caused by pesticides with temperature change and population dynamic model. Sensitive strain of two-spotted spider mite (Tetranychus urticae Koch) with kidney bean leaf as host was exposed to mixed acaricide, Acrinathrin-Spiromesifen and organotin acaricide, Azocyclotin, at 20, 25, 30, and $35^{\circ}C$, respectively. There was significant difference in mortality of T. urticae among pesticides and temperatures. We used DYMEX to simulate population density of T. urticae and predicted that the initial management time and number of chemical control would be changed in the future with climate change. There would be implications for strategies for pest management and selection process of pesticide in the future corresponding climate change.