• Korean Chemical Engineering Research
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• 제54권3호
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• pp.310-314
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• 2016

The search for natural antioxidants as alternatives to synthetic products is growing. Microalgae have emerged as a source of natural antioxidants with significant and diverse health-promoting properties. In this study, the effects of hot-water extraction conditions on total polyphenol compounds (TPC) production were investigated for lipid extracted microalgae (LEA). In order to enhance the polyphenol productivity, the extraction variables including solvents, temperature, time and ethanol concentration were optimized. The results showed hot-water extraction provided a higher extraction efficiency than the organic solvents and extraction at high temperatures showed a better extraction efficiency. While hot-water extract showed a higher extraction efficiency compared to 98% ethanol extraction, the mixture of water and ethanol (40:60 v/v) showed the highest production of polyphenols. The maximum polyphenols of 3.35 mg GAE (gallic acid equivalent)/g DM were obtained at the optimized extraction time of 10 min, $100^{\circ}C$ and 40% ethanol, respectively. Although Tetraselmis KCTC 12236BP was preprocessed by hexane to remove lipid for bio-diesel production, the results showed LEA contains relatively high level of polyphenols compared to untreated microalgae which can be used in the production of value-added materials. The predictions obtained from the developed Peleg's model were compared with the experimental data under the same operating conditions. The predicted and experimental data were consistent, indicating the reliability of the model.

• Korean Journal of Soil Science and Fertilizer
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• 제45권5호
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• pp.760-763
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• 2012

This study was conducted to investigate foliar treatment effects of organic agricultural materials for the environmentally-friendly cultivation of grape. The organic materials applied were chitosan, wood vinegar (pyroligneous acid), amino acid solution, and ginkgo leaf extract. All the organic materials were relatively strong acidic ranging lower than pH 4.6. when comparing with other organic materials, amino acid solution contained relatively high contents of selected plant nutrients, such as N, P, K, Ca, Mg, Cu, Fe, Mn, and Zn. As comparison of selected soil properties in the grape cultivating field, soil pH values were lower at the harvest stage than at the first stage of grape growing (before treating the organic materials), and electrical conductivity (EC) and soil organic matter content were higher at the harvest stage in the all plots. The concentrations of available phosphorus increased in most of the plot soils except in control plot (conventional treatment). The concentrations of exchangeable K decreased in the plot treated with ginkgo leaf extract and the control plot. The exchangeable Mg concentrations decreased in soils of all the plots. On the other hand, the concentrations of N and K in the grape leaves were higher with the treatments of chitosan and amino acid solution, P concentrations were higher with the applications of chitosan, wood vinegar and amino acid solution, and Ca and Mg concentrations were higher with chitosan and amino acid solution treatments, respectively, than with others. The yields of grape were higher, $1,581{\sim}1,583kg\;10a^{-1}$, in the control and wood vinegar treatment plots than others. Sugar contents of grape were not different among all the plots.

• Journal of the Korean Society of Marine Environment & Safety
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• 제25권6호
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• pp.772-779
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• 2019

The subsea pipeline has received considerable attention as a high-value-added industry linked to the energy and steel industries including natural resource development. The design and installation of the subsea pipeline require a variety of key technologies to carry out the project. In particular, a thorough pre-verification process through pre-commissioning is essential for the safe operation of the subsea pipeline. The hydrotesting stage in the pre-commissioning process of the subsea pipeline is known to be affected significantly by the ambient temperature change; however, there is a little study based on the theoretical and numerical approach. In this study, the method of predicting the internal temperature change using the transient heat transfer method for the stage of hydrotesting during the pre-commissioning process of the subsea pipeline and the prediction method of the pressure variation in the pipeline using it were proposed. The predicted results were compared with field test results and its effectiveness was verified. The proposed analysis procedure is expected to contribute to the productivity improvement of the subsea pipeline installation project by enabling the prediction of pressure variation through pipeline heat transfer simulation from the initial design stage of the subsea pipeline installation project.

• Korean Business Review
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• 제19권1호
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• pp.223-240
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• 2006

The purpose of this study is to review the current state of the transformational leadership and LMX approach to the study of leadership. Leadership research has witnessed a shift from traditional transactional models to a new genre of theories of transformational and charismatic leadership and LMX. Transformational leadership theories offer the promise of extraordinary individual and organizational outcomes. Leaders motivate followers to perform beyond expected levels by activating higher order needs, fostering a climate of trust, and inducing them to transcend their self-interest for the organization's sake. Numerous investigations point of the robustness of the effects of such leadership on individual and organizational outcomes such as job satisfaction, organizational commitment, and performance. LMX theory suggests that leaders do not use the same style in dealing with all subordinates, but rather develop a different type of relationship or exchange with each subordinate. These relationships range from those that are based strictly on employment contracts to those that are characterized by mutual trust, respect, liking, and reciprocal influence. LMX has been positively related to job satisfaction, productivity, and career progress of managers and negatively related to turnover and employee grievances. In conclusions, effective leaders link achievement of organizational goals to follower fulfillment of self-development goals, with the former advancing the latter.

• Korean Journal of Agricultural Science
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• 제3권2호
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• pp.184-191
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• 1976

This experiment was conducted for the control of summer depression of cool-season pasture plant. Orchard grass, tall fescue, red clover, alfalfa, and crabgrass were mulched by barley straw with depths of $100g/m^2$, $200g/m^2$ and $300g/m^2$ for 45 days -from July 1, to August 14-, and the effects on growth, yield and chemical composition were observed. The results obetain were as follow: Temperature decrease of $1.0{\sim}3.04^{\circ}C$ was followed after barley straw mulching on the grassland as compared with the control. The growth of the grasses after mulching was hastened, i. e. plant height was increasd 6.0~45% as compared with the control. Barley straw mulching with $100g/m^2$ supported the increase in yield of the grasses with an average of 32.77%, however, average yield was decreased by 7.75% with $300g/m^2$ mulching, apparently due to the rottening of grasses. Chemical compositions of mulched grasses were varied; contents of crude protein and nitrogen free extract were higher, but crude fats, fibre, and ashes were lower than those of the control.

• Asian Journal of Turfgrass Science
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• 제6권2호
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• pp.73-81
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• 1992

This study was designed to estimate on the interaction of the first productivity, light condition and to examine the ecophysiological 'characteristics of Zoysia japonica. Artificial community of Zoysia japonica was analyzed effect of matter production and growth construction under various shading condition. The results summarized this experiment were as follows ; 1. The relative growth rate(RGR) in all experimental plots was high during the growth stage of 20 days after transplanting and then tend to decrease. RGR value in severe shading or short day condition was remarkably decreased from the early growth stage. 2. The net assimilation rate(NAR) was high during the early growth stage after transplanting. and then decreased the growth proceeded. NAR value in the severe shading or short day condition plots was low. 3. The increasing rate of leaf ared ratio(LAR) was high during the early growth stage after transplanting in the control plot and 30% shading plot, but it appeared to be high 40 days after transplanting in the 50% and 70% shading plot. LAR was appeared to be negative correlation against RGR and NAR. 4. The crop growth rate(CGR) in each experimental plot was increased until 50 days after transplanting, and then decreased. After that time, the maximum CGR value appeared in the control plot(1.56g /g, 10days), 60days after transplanting. CGR had positive correlation with LAI. The optimum LAI in the control, 30%, 50%, and 70% shading plots was appeared as 2.10, 1.75, 1.25, and 0.90.

• KSBB Journal
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• 제21권6호
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• pp.479-483
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• 2006

[ ${\beta}-Glucan$ ], one of the cell wall components, is most plentiful polysaccharides in cell wall and has several advantages in immune system. In yeast ${\beta}-glucan$ is mainly contained in the yeast cell wall, and thus it is important to produce high levels of cell mass for the mass production of yeast ${\beta}-glucan$. The best carbon and nitrogen sources on cell mass production were high fructose syrup and yeast extract. Response surface methodology (RSM) was very potential tool for the optimization of process factor and medium component. It was applied to estimate the effects of medium components on the production of cell mass. Optimal concentrations of high fructose syrup and yeast extract by response surface methodology were 8.0% (v/v) and 5.2% (w/v), respectively and the cell mass predicted was $17.0\;g/{\ell}$ at 20 h of cultivation.

• KDI Journal of Economic Policy
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• 제34권1호
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• pp.87-133
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• 2012

This paper consists of two parts. The first part introduces a simple endogenous growth model. It is based on Romer(1990), but extends the original model by incorporating individual workers skill heterogeneity. Based on the heterogeneity, the model has a labor allocation mechanism between skilled (research) and unskilled (production) sectors. Different from Romer(1990), the labor allocation is determined by both demand and supply conditions of the economy. The endogenous growth model presented in this paper shows how the shape of the distribution of human capital affects on the labor allocation, hence on the employment structure, wage profile and economic growth. The model can be extended to an open economy. With the heterogeneity, the extended model explains distributional effect as well as growth effect of the economic openness. The second part provides empirical evidence in support of the extension part of the model presented in the first part. Based on the endogenous growth framework as proposed by Romer(1990) and Rivera-Batiz and Romer(1991), the model explains how economic openness affects labor allocation between skilled and unskilled sectors. According to the model, economic openness can affect labor allocation through two channels; knowledge spillover and specialization. First, the openness promotes knowledge spillover and hence increases the productivity of workers in the skilled sectors. This makes the economy employs more workers in the skilled sector. On the other hand, the openness causes global specialization which leads more employment in the skilled sector for the developed countries but at the same time, leads less employment in the skilled sector for the developing countries since the developing countries have comparative advantages in the unskilled sector. The empirical results obtained using cross country panel data in this paper support these two effects of knowledge spillover and specialization.

• Journal of the Korean Society of Food Science and Nutrition
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• 제33권1호
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• pp.170-175
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• 2004

This study was conducted to determine the minimum concentration of citrus juice for basal medium and also to search for an additional carbon source for the best production of the gel. A concentrate of citrus fruit juice of 65$^{\circ}$Brix, it was diluted to be used as a basal medium. Static cultivation of Gluconacetobacter hansenii TL-2C for 14 days at 3$0^{\circ}C$ produced the best gel with 7.5$\pm$0.4 mm thickness in the 6-fold diluted citrus Juice concentrate without any additional nutrient. However, the same thickness could be obtained with 60 to 100-fold diluted juice concentrate when refined white sugar was added at appropriate concentrations. Glucose was the most effective sugar for the both of gel and acid production, and optimal concentration of the sugar was 10$^{\circ}$Brix. Ethyl alcohol at 1.0% had synergistic effects in combination with refined sugar and increased the gel thickness up to 15.1 mm which was 1.85 times thicker than that of refined sugar alone. However, acetic acid was not effective. Gel productivity with supplement of ethanol was 172.6$\pm$8.4 g wet/L, and it was approximately equal to 4.7 g of dry gel/L.

• Journal of Environmental Science International
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• 제27권5호
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• pp.291-297
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• 2018

Vertical farming systems offer many advantages in urban spaces. They have also been proposed as an engineering solution to increase the productivity per unit area of cultivated land by extending crop production in the vertical dimension. However, soil water retention is a major constraint affecting the plant environment. This study analyzed the effects of growth environment of Tropaeolum majus and Fragaria spp., on the vertical farming system, by using four different types of cover material types including sphagnum moss (Control), a shading net (S.N.), multi-layered fabric (M.L.F.), and non-woven fabric (N.W.F.). The volumetric soil moisture contents and plant characteristics were investigated from May to September 2014. Plant materials were individually cultivated in hanging baskets measuring $30{\times}17{\times}17cm$, filled with a mixture of soil and perlite, and placed at 1.5m height. Each treatment was performed in quadruplicate and consisted of five plants, amounting to a total of 20 plants. The analysis indicated that different covers were associated with multiple functions and soil water retention improvements may have a positive impact on the vertical farming system. The difference in soil water retention increased in the following order: M.L.F. > Control > N.W.F. > S.N.. Furthermore, the differences in plant height and survival rate increased in the following order: M.L.F. > Control > N.W.F. > S.N. Therefore, M.L.F yielded satisfactory good response for the vertical farming system of cover materials. Our results clearly demonstrate that vertical spaces represent an attractive alternative to urban farming and suggest that further increases in yield may be achieved via different cover materials in vertical farming using hanging baskets.