• Analytical Science and Technology
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• v.24 no.6
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• pp.544-555
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• 2011

The acute toxicity in the rainbow trout (Oncorhynchus mykiss) was analyzed and predicted using quantitative structure-activity relationships (QSAR). The aquatic toxicity, 96h $LC_{50}$ (median lethal concentration) of 275 organic pesticides, was obtained from EU-funded project DEMETRA. Prediction models were derived from 558 2D molecular descriptors, calculated in PreADMET. The linear (multiple linear regression) and nonlinear (support vector machine and artificial neural network) learning methods were optimized by taking into account the statistical parameters between the experimental and predicted p$LC_{50}$. After preprocessing, population based forward selection were used to select the best subsets of descriptors in the learning methods including 5-fold cross-validation procedure. The support vector machine model was used as the best model ($R^2_{CV}$=0.677, RMSECV=0.887, MSECV=0.674) and also correctly classified 87% for the training set according to EU regulation criteria. The MLR model could describe the structural characteristics of toxic chemicals and interaction with lipid membrane of fish. All the developed models were validated by 5 fold cross-validation and Y-scrambling test.

• Journal of Korea Port Economic Association
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• v.23 no.3
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• pp.79-101
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• 2007

The purpose of this study is to identify key factors of Co-opetition through examining the environmental and structural changes in the ports industry and suggest a few Co-opetition strategies for enhancing our ports capabilities in the long-term. In recent years, the trend toward market liberalization and globalization in ports industry has made rapid progress and it made the competition fiercer. To survive in this rapid changes, the ports have traditionally pursed a competitive strategy. However, an alternative strategy replacing the traditional strategy was introduced: namely, 'Co-opetition' a buzzword combining competition and co operation. Policy proposals this study suggests are the construction of a database regarding costs and benefits of ports for more effective analysis and improving the competitive power of a shipping company operating national flag carriers for achieving the purpose of Co-opetition and adoption of selection and concentration strategy for increasing the possibility of Co-opetition success.

• Korean Journal of Plant Resources
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• v.33 no.4
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• pp.303-310
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• 2020

This study was conducted on propagation use for conservation scheme of a threatened plant; Wikstroemia ganpi (Sieb. et Zucc.) Maxim(Geomundo false ohelo). The seed propagation was showed higher (95%) in storage and lower values in ground and cutting. Softwood cutting was higher than hardwood cutting and it was possessing higher ratio of rooting that increase concentration of IBA and NAA. It was determined that for Geomundo false ohelo seedling was effective than cutting. In-situ and ex-situ conservation and restoration of substitute habitats of Geomundo false ohelo is therefore necessary due to human trampling in the habitats, damage, natural selection, loss and suppression.

• Journal of Korea Water Resources Association
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• v.43 no.3
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• pp.245-256
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• 2010

We study the basic theory and applicability of the WQUAL block in the FFC2Q model and the characteristics of non-point pollutant loads during the early stage of runoff. Study is also performed on selection of the values of the related parameters and their effect on the simulation results. FFC2Q simulation results are compared for verification with the measured data for three rainfall events in the Gunja Subbasin and found to be similar to the measured data in peak-flows, total runoff volumes, total loads, peak concentrations and times of peak concentration. This model thus shows results very close to those applying the SWMM and MOUSE models, even though it uses simplified input data. Related to rainfall distribution, under the condition of Huff 1st quartile distribution the pollutant loads occurred earlier than under other conditions, and in the early stage of rainfall the BOD and COD loads increased faster than the SS loads. The NPS loads were concentrated in the early stage of rainfall and finally reached total loads, so the rainfall after that could not contribute so much to the NPS loads.

• Reproductive and Developmental Biology
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• v.33 no.3
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• pp.171-177
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• 2009

Spermatogonial stem cells(SSCs) only are responsible for the generation of progeny and for the transmission of genetic information to the next generation in male. Other in vitro studies have cultured SSCs for proliferation, differentiation, and genetic modification in mouse and rat. Currently, information regarding in vitro culture of porcine Germline Stem Cell(GSC) such as gonocyte or SSC is limited and is in need of further studies. Therefore, in this study, we report development of a successful culture system for gonocytes of neonatal porcine testes. Testis cells were extracted from $10{\sim}14$-day-old pigs. These cells were harvested using enzymatic digestion, and the harvested cells were purified with combination of percoll, laminin, and gelatin selection techniques. The most effective culture system of porcine gonocytes was established through trial experiments which made a comparison between different feeder cells, medium, serum concentrations, temperatures, and $O_2$ tensions. Taken together, the optimal condition was established using C166 or Mouse Embryonic Fibroblast(MEF) feeder cell, Rat Serum Free Medium(RSFM), 0% serum concentration, $37^{\circ}C$ temperature, and $O_2$ 20% tension. Although we discovered the optimal culture condition for proliferation of porcine gonocytes, the gonocyte colonies ceased to expand after one month. These results suggest inadequate acquirement of ingredients essential for long term culture of porcine GSCs. Consequently, further study should be conducted to establish a successful long-term culture system for porcine GSCs by introducing various growth factors or nutrients.

• Journal of the Economic Geographical Society of Korea
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• v.8 no.1
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• pp.131-152
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• 2005

The purpose of this paper is to find out the spatial characteristics of the relationships between urban large retailer and agro-food suppliers. For this purpose, Dong-A department store which is one of the most famous local distribution company was selected as a case study firm. The case study company has its own systematic food supply chain in the process of food procurement, selection, delivery, and marketing. It mainly does businesses in Daegu and Gyeongbuk province, but also procures and delivers products all around the country. Customers' recent concerns over the freshness and the period of circulation made the company use the local physical distribution system that it purchases products in nearby areas and perform procurement and delivery in nationwide areas. It is identified that trading types are significantly different by locations of suppliers in that more thin 40$\%$ of suppliers in Daegu are food manufacturers, whereas suppliers in Gyeongbuk mainly belong to the ones in fresh food production areas. In terms of durability of the retailer-supplier relation, the case study firm has relatively long-term relationship with suppliers, maintaining the relationship fer over 5 years in more than 70$\%$ of suppliers.

• Journal of Korea Technology Innovation Society
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• v.17 no.4
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• pp.651-672
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• 2014

Under the diagnosis of low employment rate and low growth, the government regards the creation of new jobs through the creative and innovative R&D as an important national plans. This study attempts to measure the employment creation effect of R&D investment of industrial technology by using input-output analysis used in domestic and international broadly. The employment effect can be divided into employment inducement effect and direct employment effect. As a result of the analysis, The employment creation effect of R&D investment of government industrial technology is measured to be 8-12 peoples per 1 billion KRW investment. This results mean that government R&D investment is a effective policy for employment creation. And it is necessary to establish R&D policies that reflect the technical characteristics of the employment creation effect. In short term, it is important that the government invest the superior technology of total employment and direct employment as essential means of employment creation by selection and concentration strategy. In mid-long term, the government should focus on technology spread as technology transfer and opening innovation strategy for employment creation to support superior technology of employment inducement. The results of this study can be used in analysis on the employment creation effect related to industrial technology R&D.

• Journal of Life Science
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• v.20 no.10
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• pp.1544-1548
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• 2010

Moxifloxacin (MF) - resistant mutants of Mycoplasma hominis (M. hominis) were generated by stepwise selection in increasing concentrations of MF, and six strains of MF resistant M. hominis mutants - M1, M4, M8, M16, M32, and M64 - in which MICs of MF were 0.5, 4, 8, 16, 32, 64 ${\mu}g$/ml, respectively, were generated. Compared to the sequence of M. hominis PG21, all mutants harbored amino acid substitutions of Arg-163 Thr in GyrA, and Pro-445 Gln in ParE. While the concentrations were getting higher, an additional amino acid substitution was found at Ser-153 Lys in GyrA (${\geq}4{\mu}g/ml$), Ser-91 Ile in ParC (${\geq}16{\mu}g/ml$), and Val-450 Phe (${\geq}64{\mu}g/ml$) in GyrB. These substitutions seem to have an impact on resistance to MF, and GyrB change was found only in the highest concentration and seems to be associated with high-level resistance to MF. This, as far as we know, is the first description of a relationship between MF resistance phenotype and genotype.

• Journal of Korea Foresty Energy
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• v.24 no.2
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• pp.31-36
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• 2005

Cauliflower mushroom (Sparassis crispa) is an edible mushroom that shows remarkably high contents of $1,3-{\beta}-D-glucan$ compared to other edible mushrooms. The mushroom is known to give high antitumor and immunologic activities, thus the mushroom is recently cultivated in Japan and Korea. However, cultivation methods are being kept in secret or under patents by some companies with complicated procedures. This study was conducted to solve the problem by providing a simple method for the cultivation of cauliflower mushroom. We could produce the mushroom using sawdust-based media of Larix leptolepis, Pinus densiflora and P. koraiensis with addition of barley flours and sugar. The ratio of the sawdust : barley flours : sugar used for this study was 80:20:3 in dry-weight base, and the water content was adjusted as 65%. The productivity was somewhat different among the species of sawdust media and the strains of Sparassis crispa for the cultivation, and the mushroom production reached up to 177g from 650g base(productivity : 27%). Thus, this medium is strongly recommended as a practical cultivation method for cauliflower mushroom. By the way, further study for the determination of adequate concentration of barley flour and the selection of proper strain for each sawdust species is needed.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.561-567
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• 2013

Mixed hardwood chips were pre-pulping extracted with green liquor prior to kraft pulping in order to recover hemicelluloses for use as biofuels. This green liquor solution containing mainly sodium sulfide and sodium carbonate was applied at different alkali charges (expressed as $Na_2O$) of 0, 1, 3, and 5% on dry wood weight. The extractions were performed at $160^{\circ}C$ for residence times ranging from about 1-2 h to determine the effect of extraction severity on composition of the pre-pulping extract. The severity of hemicellulose extraction time and green liquor charge controls the concentration of acetic acid and monosaccharide sugars available for downstream processing, the accumulation of degradation products such as organic acids and furans in the extract. As the alkali charge was increased, the amount of acetate side chains on the hemicelluloses and the dissolved lignin in the extract increased but the carbohydrate and sugars in the extract decreased appreciably. Hot water extraction (0% alkali addition) released the greatest amount of carbohydrates, up to 29.80 g/L measured as component sugars, but resulted in the greatest decrease in pulp yield. Meanwhile, pre-pulping extraction with 3% green liquor increased the pulp yield while greatly reducing the component sugars to 7.08 g/L. Fundamental data obtained in this study will allow selection of optimum hemicellulose extraction conditions for integrating the extraction operation into the Kraft pulping process.