• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.773-784
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• 2008

Even if the exploitation of copper slag produced during the smelting process of copper as aggregate for construction purpose has been permitted since 2004 in Korea, the lack of sufficient data enabling to evaluate its long-term stability that is its durability has to date impeded its application. This study intends to investigate experimentally the durability characteristics of 18 and 27 MPa-class commercial concretes in which natural sand (fine aggregates) has been partially replaced by copper slag through accelerated and exposure tests so as to provide bases promoting the application of copper slag concrete. The experimental results revealed insignificant difference of the durability characteristics in most of the mix proportions in which 30% of natural sand was replaced by copper slag. In the case where crushed sand was adopted, tests verified similar characteristics for replacement ratio of 50%. Particularly, the results of the exposure test conducted during 8 years demonstrated that equivalent level of durability was secured compared to the case using natural sand. In the case of 18MPa-class lower grade concrete, exposure test verified also that the physical lifetime similar to 50 years could be secured until carbonation reaches cover depth of 20 mm.

• Journal of Forest and Environmental Science
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• v.29 no.4
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• pp.257-274
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• 2013

Ecological and ethnomedicinal survey of plants was conducted in one hundred and twenty homesteads in Mbala, Amuda, Umuaku, and Nneato communities of Nneochi Local Governement Area, Abia State-Nigeria. A total of ninety-one medicinal plant species belonging to seventy-eight genera and forty-eight families, used in the treatment of malaria, yellow fever, fibroid, hepatitis, convulsion, hypertension, diabetes, insomnia, ulcer, rashes, low sperm count, snake bite, among others, were documented. Plant remedies were prepared mostly as infusions or decoctions from different plant parts with mainly water, and palm wine/gin sometimes. The highest number of medicinal plant species (73) was recorded in Mbala, followed by Amuda (71), Umuaku (68) and Nneato (61). Medicinal plant species diversity was highest in Amuda (Simpson 1-D=0.9621;H=3.663), followed by Umuaku (Simpson 1-D=0.9481; H=3.471), Mbala (Simpson 1-D=0.9345; H=3.341), and Nneato (Simpson 1-D=0.9307; H=3.277), respectively. Similarity in medicinal plant species was highest between Umuaku and Nneato (76.71%), followed by Amuda and Umuaku (75.95%), Mbala and Amuda (71.43%), while Mbala and Nneato had the lowest similarity (59.52%). The results of the study showed that traditional medicine is pivotal in the treatment of ailments in the study area, and that the indigenous people of Nneochi have recognized the need to conserve medicinal plants of importance ex situ within homesteads due to threats from unsustainable exploitation and deforestation.

• Journal of Ecology and Environment
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• v.31 no.1
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• pp.1-7
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• 2008

In this minireview we focus on how males may exploit female's sensitivity to predation risk in the context of mating. It has been shown in studies on guppies and jumping spiders that in response to altered female behaviors, which are adaptations to the unfavorable environment and a consequence of females' higher sensitivity to predator's presence as well as females' higher predation risk, males can adopt condition-dependent mating tactics. It appears that in such cases males do not modify their reproductive behavior directly in response to their own perception of predation risk, but indirectly in response to changes in female behavior induced by predator presence. It has also been recently shown in crabs that males can exploit female behavior by creating safer habitat spots, which increases the male mating success. Hence all the evidence suggests that males not only respond to female sensitivity to the natural variation in predation risk, but that males can also exploit female behavior by altering the environment. As a logical extension of these findings, we present a hypothesis that in certain conditions males can manipulate the environment in order to increase the predation risk and to induce female behaviors that enhance the male's mating success with the increased predation risk. We propose that such a manipulation to increase predation risk is expected to evolve in males of species with a strong sexual conflict and female-biased predation risk. Although empirical evidence has not been yet shown, initial observations in a water strider species in Korea, Gerris gracilicornis, seem to support this hypothesis.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1491-1499
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• 2010

Rhizosphere microorganisms possessing phytase activity are considered important for rendering phytate-phosphorus (P) available to plants. In the present study, the Citrobacter braakii phytase gene (appA) was overexpressed in rhizobacteria possessing plant growth promoting (PGP) traits, for increasing their potential as bioinoculants. AppA was cloned under the lac promoter in the broadhost-range expression vector pBBR1MCS-2. Transformation of the recombinant construct pCBappA resulted in high constitutive phytase activity in all of the eight rhizobacterial strains belonging to genera Pantoea, Citrobacter, Enterobacter, Pseudomonas (two strains), Rhizobium (two strains), and Ensifer that were studied. Transgenic rhizobacterial strains were found to display varying levels of phytase activity, ranging from 10-folds to 538-folds higher than the corresponding control strains. The transgenic derivative of Pseudomonas fluorescens CHA0, a well-characterized plant growth promoting rhizobacterium, showed the highest expression of phytase (~8 U/mg) activity in crude extracts. Although all transformants showed high phytase activity, rhizobacteria having the ability to secrete organic acid showed significantly higher release of P from Ca-phytate in buffered minimal media. AppA overexpressing rhizobacteria showed increased P content, and dry weight (shoot) or shoot/ root ratio of mung bean (Vigna radiata) plants, to different extents, when grown in semisolid agar (SSA) medium containing Na-phytate or Ca-phytate as the P sources. This is the first report of the overexpression of phytase in rhizobacterial strains and its exploitation for plant growth enhancement.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2076-2086
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• 2016

Fungal cytochrome P450 (CYP) enzymes catalyze versatile monooxygenase reactions and play a major role in fungal adaptations owing to their essential roles in the production avoid metabolites critical for pathogenesis, detoxification of xenobiotics, and exploitation avoid substrates. Although fungal CYP-dependent biotransformation for the selective oxidation avoid organic compounds in yeast system is advantageous, it often suffers from a shortage avoid intracellular NADPH. In this study, we aimed to investigate the use of bacterial glucose dehydrogenase (GDH) for the intracellular electron regeneration of fungal CYP monooxygenase in a yeast reconstituted system. The benzoate hydroxylase FoCYP53A19 and its homologous redox partner FoCPR from Fusarium oxysporum were co-expressed with the BsGDH from Bacillus subtilis in Saccharomyces cerevisiae for heterologous expression and biotransformations. We attempted to optimize several bottlenecks concerning the efficiency of fungal CYP-mediated whole-cell-biotransformation to enhance the conversion. The catalytic performance of the intracellular NADPH regeneration system facilitated the hydroxylation of benzoic acid to 4-hydroxybenzoic acid with high conversion in the resting-cell reaction. The FoCYP53A19+FoCPR+BsGDH reconstituted system produced 0.47 mM 4-hydroxybenzoic acid (94% conversion) in the resting-cell biotransformations performed in 50 mM phosphate buffer (pH 6.0) containing 0.5 mM benzoic acid and 0.25% glucose for 24 h at $30^{\circ}C$. The "coupled-enzyme" system can certainly improve the overall performance of NADPH-dependent whole-cell biotransformations in a yeast system.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.101-104
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• 2005

To understand the geologic and hydrogeochemical controls on the occurrence of high fluoride concentrations in bedrock groundwaters in South Korea, we examined a total of 367 hydrochemistry data obtained from deep groundwater wells (avg, depth = 600 m) that were drilled for exploitation of hot springs. The fluoride concentrations were generally very high (avg. 5.65 mg/L) and exceeded the Drinking Water Standard (1.5 mg/L) in 72% of the samples, A significant geologic control of fluoride concentrations was observed: the highest concentrations occur in the areas of granitoids and granitic gneiss, while the lowest concentrations in the areas of volcanic and sedimentary rocks. In relation to the hydrochemical facies, alkaline $Na-HCO_3$ type waters had remarkably higher F concentrations than circum-neutral to slightly alkaline $Ca-HCO_3$ type waters. The Prolonged water-rock interaction occurring during the deep circulation of groundwater in the areas of granitoids and granitic gneiss is considered most important for the generation of high F concentrations. Under such condition, fluoride-rich groundwaters are likely formed through hydrogeochemical processes consisting of the removal of Ca from groundwater via calcite precipitation and/or cation exchange and the successive dissolution of plagioclase and F-bearing hydroxyl minerals (esp. biotite). Thus, groundwaters with high pH and very high Na/Ca ratio within granitoids and granitic gneiss are likely most vulnerable to the water supply problem in relation to the enriched fluorine.

• Animal cells and systems
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• v.13 no.4
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• pp.419-427
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• 2009

The Minke whale, Balaenoptera acutorostrata, is the smallest baleen whale in the suborder Mysticeti. Because this species inhabits coastal areas, it became a main target species of coastal small-type whaling in the North Atlantic and the Northwest Pacific Oceans, and the species' population size dramatically decreased because of over-exploitation. As a result, the International Whaling Commission declared a global moratorium on whaling and launched the development of a management procedure for protecting the whales. Morphological studies, whaling history analysis, and genetic studies conducted mainly by Japanese scientists showed the existence of one unique "E" stock that inhabits the waters around the Korean peninsula and mixes with the "O" stock in the southern part of the Sea of Okhotsk. We used the mitochondrial DNA control region polymorphism of 348 Minke whales bycaught or stranded in Korean waters from 30 October 1998 to 25 June 2005 to assess the whale population structure by year. The frequency of the 10 major haplotypes from the 40 identified haplotypes was not significantly different among groups, suggesting that a subpopulation was not present. A comparison of the genetic distances calculated with Tamura-Nei's method showed that the distances between groups were lower than those within groups, which suggests that there was no genetic difference in the Minke whale populations. The Fst comparison between groups and the phylogenetic tree constructed using the unweighted pair group method with arithmetic mean (UPGMA) and Neighbor Joining (NJ) method also detected no obvious sub-stock structure.

• The Journal of the Petrological Society of Korea
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• v.24 no.3
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• pp.233-252
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• 2015

This research are systematic and scientific approaches to obtain the distribution, occurrence and quality of granite stone for building purposes. The process of dimension stone exploration must be carried out to know the underground potentiality of granitic body using the basic data collection and study, field mapping, detailed drilling survey, televiewer technique, and physical and chemical tests in the Geochang area. Televiewer data obtained in drilling boreholes can be accurately distinguished from the discontinuous face, strike and inclination, extension which is difficult to obtain in a core logging. 3D joint images will be helpful to establish a quarry exploitation plan because the 3D joint images give quite accurate information down to depth below the outcrop surface. Through the process of the quality estimation on the Geochang site, the proven reserve estimated as dimensional building stone are calculated with good quality in petrologic and physical properties.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.8
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• pp.103-115
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• 2020

In many countries, the Government enacts tax laws in order to manage tax collection and regulate the macro-economy. According to Noor, Jamaludin, Omar, and Aziz (2013), tax non-compliance is a growing concern because of its negative effects on the state budget. The main objectives of this article are to identify the factors affecting corporate income tax non-compliance of enterprises in Ho Chi Minh City in accordance with the current situation of Vietnamese tax administration. We use several research methods, including the exploitation of information and practical experiences from both taxpayers and tax authorities; with Probit regression model on a sample of 187 enterprises that have been inspected or examined by tax authorities in Vietnam during the period from 2013 to 2017.The article identified eight factors affecting corporate income tax (CIT) non-compliance: (1) working capital/total assets; (2) revenue/total assets; (3) total debt/total assets; (4) loss in the previous year; (5) receivables/revenue; (6) the size of enterprises; (7) tax administrative penalties/tax payable; and (8) business field. In particular, the tax non-compliance was studied as a violation of Vietnamese tax laws by enterprises declaring an insufficient amount of CIT payable to the State budget.

• Korean Business Review
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• v.11
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• pp.343-364
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• 1998

The results of the study show that managers of Korean manufacturing firms pursue international business strategy(IBS) to achieve four different objectives: global integration, national responsiveness, market expansion, or development and exploitation of firm-specific knowledge. IBS is closely related to the international business environment of the firms. When managers think they can exploit economies of scale by integrating worldwide operations, they prefer the global standardization strategy. Managers of firms which implement the localization strategy actively recognize the importance of the strategy more than those of other firms. IBS helps to improve the overall international competitiveness of the firms. Especially. implementing global standardization and localization simultaneously seems to be useful to strengthen the competitiveness of the firms.