• Journal of Microbiology and Biotechnology
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• v.25 no.1
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• pp.109-118
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• 2015

Open raceway ponds are cost-efficient for mass cultivation of microalgae compared with photobioreactors. Although low-cost options like wastewater as nutrient source is studied to overcome the commercialization threshold for biodiesel production from microalgae, a cost analysis on the use of wastewater and other incremental increases in productivity has not been elucidated. We determined the effect of using wastewater and wavelength filters on microalgal productivity. Experimental results were then fitted into a model, and cost analysis was performed in comparison with control raceways. Three different microalgal strains, Chlorella vulgaris AG10032, Chlorella sp. JK2, and Scenedesmus sp. JK10, were tested for nutrient removal under different light wavelengths (blue, green, red, and white) using filters in batch cultivation. Blue wavelength showed an average of 27% higher nutrient removal and at least 42% higher chemical oxygen demand removal compared with white light. Naturally, the specific growth rate of microalgae cultivated under blue wavelength was on average 10.8% higher than white wavelength. Similarly, lipid productivity was highest in blue wavelength, at least 46.8% higher than white wavelength, whereas FAME composition revealed a mild increase in oleic and palmitic acid levels. Cost analysis reveals that raceways treating wastewater and using monochromatic wavelength would decrease costs from 2.71 to 0.73 $/kg biomass. We prove that increasing both biomass and lipid productivity is possible through cost-effective approaches, thereby accelerating the commercialization of low-value products from microalgae, like biodiesel.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.201-212
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• 2011

Nanotechnology is the applied science which develops new materials and systems sized within 1 to 100 nanometer, and improves their physical, chemical, and biological characteristics by manipulating on an atomic and molecular scale. This nanotechnology has been applied to wide spectrum of industries resulting in production of various nanoparticles. It is expected that more nanoparticles will be generated and enter to natural water bodies, imposing great threat to potable water resources. However their toxicity and treatment options have not been throughly investigated, despite the significant growth of nanotechnology-based industries. The objective of this study is to provide fundamental information for the management of nanoparticles in water supply systems through extensive literature survey. More specifically, two types of nanoparticles are selected to be a potential problem for drinking water treatment. They are carbon nanoparticles such as carbon nanotube and fullerene, and metal nanoparticles including silver, gold, silica and titanium oxide. In this study, basic characteristics and toxicity of these nanoparticles were first investigated systematically. Their monitoring techniques and treatment efficiencies in conventional water treatment plants were also studied to examine our capability to mitigate the risk associated with nanoparticles. This study suggests that the technologies monitoring nanopartilces need to be greatly improved in water supply systems, and more advanced water treatment processes should be adopted for better control of these nanoparticles.

• Archives of Plastic Surgery
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• v.39 no.1
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• pp.36-41
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• 2012

Background : Poststernotomy mediastinitis is a rare, but life-threatening complication, thus early diagnosis and proper management is essential for poststernotomy mediastinitis. The main treatment for mediastinitis is aggressive debridement. Several options exist for reconstruction of defects after debridement. The efficacy of immediate debridement and reconstruction with a pectoralis major muscle flap designed for the defect immediately after the diagnosis of poststernotomy mediastinitis is demonstrated. Methods : Between September 2009 and June 2011, 6 patients were referred to the Department of Plastic and Reconstructive Surgery and the Department of Thoracic and Cardiovascular Surgery of Ajou University Hospital for poststernotomy mediastinitis. All of the patients underwent extensive debridement and reconstruction with pectoralis major muscle flaps, advanced based on the pedicle of the thoracoacromial artery as soon as possible following diagnosis. A retrospective review of the 6 cases was performed to evaluate infection control, postoperative morbidity, and mortality. Results : All patients had complete wound closures and reduced severity of infections based on the erythrocyte sedimentation rate and C-reactive protein levels and a reduction in poststernal fluid collection on computed tomography an average of 6 days postoperatively. A lack of growth of organisms in the wound culture was demonstrated after 3 weeks. There were no major wound morbidities, such as hematomas, but one minor complication required a skin graft caused by skin flap necrosis. No patient expired after definitive surgery. Conclusions : Immediate debridement and reconstruction using a pectoralis major muscle flap is a safe technique for managing infections associated with poststernotomy mediastinitis, and is associated with minimal morbidity and mortality.

• Health Policy and Management
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• v.30 no.2
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• pp.192-198
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• 2020

Background: Korea National Health Insurance Service (NHIS) is operated as a social insurance system in which people pay a portion of their monthly income as insurance premiums and receive benefits when they experience illness or injury. Since 2005, the national health insurance remained surplus accumulating cumulative reserves each year. However, as of 2018, NHIS revenue recorded 62.11 trillion won and spending of 62.29 trillion won. The deterioration of NHIS finances is expected to accelerate with the aging population, income growth, new medical technology development, and enhanced security policies. Methods: To examine the financial health and sustainability of NHIS, we estimated the future revenue and spending until 2030 using the data from Korea Health Insurance Review and Assessment Service statistical yearbook. 2004-2018 average percentage change in NHIS revenue and spending was calculated. We estimated the future NHIS financial status using two methods. In the first method, we calculated the revenue and spending of the future NHIS by applying the 2004-2018 average percentage change to the subsequent years consecutively. In the second method, we estimated the future NHIS financial status after adjusting for the predicted demographic changes such as the aging population and declining birth rate in South Korea. Results: The estimates from this study suggest that the NHIS's cumulative reserves will run out by 2024. Conclusion: In terms of spending on current health insurance, there should be a search for ways of more efficient spending and funding options.

• Wind and Structures
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• v.15 no.1
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• pp.17-26
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• 2012

Modeling swirling wakes is of considerable interest to wind farm designers. The present work is an attempt to develop a computational tool to understand free, far-wake development behind a single rotating wind turbine. Besides the standard momentum and continuity equations from the boundary layer theory in two dimensions, an additional equation for the conservation of angular momentum is introduced to study axisymmetric swirl effects on wake growth. Turbulence is simulated with two options: the standard ${\kappa}-{\varepsilon}$ model and the Reynolds Stress transport model. A finite volume method is used to discretize the governing equations for mean flow and turbulence quantities. A marching algorithm of expanding grids is employed to enclose the growing far-wake and to solve the equations implicitly at every axial step. Axisymmetric far-wakes with/without swirl are studied at different Reynolds numbers and swirl numbers. Wake characteristics such as wake width, half radius, velocity profiles and pressure profiles are computed. Compared with the results obtained under similar flow conditions using the computational software, FLUENT, this far-wake model shows simplicity with acceptable accuracy, covering large wake regions in far-wake study.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.220-220
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• 2015

Water, energy, and food security already became a risk that threatens people around the world. Increasing of resources demand, rapid urbanization, decreasing of natural resources and climate change are four major problems inducing resources' scarcity. Indeed, water, energy, and food are interconnected each other thus cannot be analyzed separately. That is, for simple example, energy needs water as source for hydropower plant, water needs energy for distribution, and food needs water and energy for production, which is defined as W-E-F nexus. Due to their complicated linkage, it needs a computer model to simulate and analyze the nexus. Development of a computer simulation model using system dynamics approach makes this linkage possible to be visualized and quantified. System dynamics can be defined as an approach to learn the feedback connections of all elements in a complex system, which mean, every element's interaction is simulated simultaneously. Present W-E-F nexus models do not calculate and simulate the element's interaction simultaneously. Existing models only calculate the amount of water and energy resources that needed to provide food, water, or energy without any interaction from the product to resources. The new proposed model tries to cope these lacks by adding the interactions, climate change effect, and government policy to optimize the best options to maintain the resources sustainability. On this first phase of development, the model is developed only to learn and analyze the interaction between elements based on scenario of fulfilling the increasing of resources demand, due to population growth. The model is developed using the Vensim, well-known system dynamics model software. The results are amount of total water, energy, and food demand and production for a certain time period and it is evaluated to determine the sustainability of resources.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.1006-1014
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• 2020

Consumer expectations for drama VFX increased as the influx of overseas dramas increased due to the growth of OTT service, but the current production time of the drama production system has a negative effect on the quality and completion of work. This paper proposes a background rendering using a game engine and a subject rendering using background HDRI as environmental lighting. The proposed workflow is expected to reduce the production time of VFX and improve the quality of VFX. The proposed workflow was verified in 3 steps. Comparing game engine and rendering software according to the same lighting environment and camera distance, comparing rendering with existing rendering method and background HDRI generation, and validating the proposed workflow. For verification, quantitative evaluation was performed using Structual similarity index and histogram. This study is expected to be one of the options to improve the quality of VFX and improve the risk.

• The Journal of Bigdata
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• v.5 no.2
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• pp.231-240
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• 2020

With the development in the IT industry and the growth in the game industry, user's game data is recorded in seconds according to various plays and options, and a vast amount of game data can be analyzed based on Bigdata. Combined with business, Bigdata is used to discover new values for profit creation in various fields, but it is utilized in the game industry in insufficient ways. In this study, considering the characteristics of the subdivided lines, we constructed a win-loss prediction model for each line using the game data of League of Legends, and derived the importance of variables. This study can contribute to planning of strategies for general game users to get information about team members in advance and increase the win rate by using the record search sites.

• Journal of Korea Trade
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• v.24 no.1
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• pp.1-34
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• 2020

Purpose - In this study, we investigate determinants of hedging with derivatives and its effect on firm value and firm risk for Korean firms. Design/methodology - To avoid the endogeneity problem pointed out in previous studies, we use a two-stage analysis by using gains and losses from derivatives as instrument variable for hedging with derivatives. Findings - Our analysis on the determinants of hedging shows that firms that are more leveraged and less profitable, and with more growth opportunities are likely to hedge through derivatives. Additionally, large firms, firms less diversified into industry, and firms more diversified geographically are likely to use derivatives. Our two-stage analysis shows that indicators of hedging with derivatives have an insignificant effect on firm value, and the indicator of futures/forwards use and of swaps use have significant negative effect on firm value. Whereas, the extent of hedging with derivatives has positive effect on firm value for all types of foreign currency derivatives, which suggests that moderately low hedgers use derivatives inefficiently, but extensive hedgers use derivatives properly. With regard to firm risk, hedging with derivatives increases market-based risk, but decreases accounting-based risk. Thus, we conclude that Korean firms use derivatives to manage operational volatility rather than to manage market risk, and accounting-based risk reduction through hedging is not directly translated into higher firm value. Originality/value - This is not the first study to investigate hedging behavior of Korean firms, but the sample period that that this study analyzed is the longest and various method are used to control the endogeneity problem. We investigate not only total foreign currency derivatives but also by types of derivatives, including futures/forwards, options, and swaps.

• Molecules and Cells
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• v.45 no.8
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• pp.550-563
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• 2022

Hepatocellular carcinoma (HCC) is an aggressive and incurable cancer. Although understanding of the molecular pathogenesis of HCC has greatly advanced, therapeutic options for the disease remain limited. In this study, we demonstrated that SETD5 expression is positively associated with poor prognosis of HCC and that SETD5 depletion decreased HCC cell proliferation and invasion while inducing cell death. Transcriptome analysis revealed that SETD5 loss downregulated the interferon-mediated inflammatory response in HCC cells. In addition, SETD5 depletion downregulated the expression of a critical glycolysis gene, PKM (pyruvate kinase M1/2), and decreased glycolysis activity in HCC cells. Finally, SETD5 knockdown inhibited tumor growth in xenograft mouse models. These results collectively suggest that SETD5 is involved in the tumorigenic features of HCC cells and that targeting SETD5 may suppress HCC progression.