• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.588-598
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• 2017

Currently, bioethanol, a fuel additive for transportation, is produced mainly by using biomass (first generation) such as corn and sugar canes. First generation biomass can cause various problems in terms of increase in agricultural prices and ethical reasons. To address these problems, a nonedible lignocellulosic biomass can be utilized. Agricultural byproducts such as straw, bagasse, and forest byproducts from the wood processing industry. Therefore, production of wood based bioethanol can be an effective utilization route of second generation biomass, and its raw materials are more abundant than first generation resources. Furthermore, it is possible to secure cheap raw materials. One of the biggest advantages of using biofuels is that it contributes to the reduction of greenhouse gases by minimizing the environmental impact, unlike fossil fuels. In this study, we investigated the greenhouse gas reduction effects that can be achieved through the use of Lignocellulosic bioethanol and government policies on renewable energy currently being implemented in ASEAN countries (Indonesia, Malaysia, Thailand and the Philippines). In these four countries, policies and incentives related to biofuels have been developed. It is expected that the reduction ratio of carbon dioxide emission and the mixed biofuel will be gradually increased in the future.

• Journal of Energy Engineering
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• v.22 no.2
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• pp.184-196
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• 2013

We need to develop new renewable energy that could fundamentally replace fossil fuel, since the volume of economy and industry of our time becomes uncontrollably enormous. One of the alternative is to develop energy based on marine biomass, which would meet environment and energy needs at the same time. The marine bio-energy productions is supposed to occupy 50% to 500 million TOE in bio-energy production that is based on the Korean 3rd new renewable energy technology development, utilization, supply plan until 2030. This study attempts to apply input-output analysis to investigating the economic impacts of marine bio-energy development project in the Korean national economy. More specifically, this study shows what national economy effect of production-inducing effect, value-added inducing effect, employment-inducing effect, and R&D-inducing effect are explored with demand-driven model. Furthermore, this study attempts to define and classify the marine bio-energy development project sector from I-O table. Also, this study pays particular attention to marine bio-energy development project by taking the industry as exogenous specification and then investigating its economic impacts. The Marine bio-energy development project case 223 billion won, production-inducing effect, value-added inducing effect, and employment-inducing effect are 312 billion won, 87 billion won, 1,151 persons, and 5 billion won respectively. These quantitative information can be usefully utilized in the policy-making for the industrialization of marine bio-energy development project.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.239-247
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• 2013

Recently renewable energy such as offshore wind energy takes a higher interest due to the depletion of fossil fuel and the environmental pollution. This paper deals with multi-body dynamics (MBD) analysis technique for offshore wind turbine system considering aerodynamic loads and Thevenin equation used for determination of electric generator torque. Dynamic responses of 5MW offshore wind turbine system are evaluated via the MBD analysis, and the system is the horizontal axis wind turbine (HAWT) which generates electricity from the three blades horizontally installed at upwind direction. The aerodynamic loads acting on the blades are computed by AeroDyn code, which is capable of accommodating a generalized dynamic wake using blade element momentum (BEM) theory. In order that the characteristics of dynamic loads and torques on the main joint parts of offshore wind turbine system are simulated similarly such an actual system, flexible body modeling including the actual structural properties are applied for both blade and tower in the multi-body dynamics model.

• Journal of KIISE:Software and Applications
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• v.41 no.7
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• pp.481-491
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• 2014

The power production using renewable energy is more important because of a limited amount of fossil fuel and the problem of global warming. A concentrative photovoltaic system comes into the spotlight with high energy production, since the rate of power production using solar energy is proliferated. These systems, however, need to sophisticated tracking methods to give the high power production. In this paper, we propose a hierarchical tracking system using modular Bayesian networks and a naive Bayes classifier. The Bayesian networks can respond flexibly in uncertain situations and can be designed by domain knowledge even when the data are not enough. Bayesian network modules infer the weather states which are classified into nine classes. Then, naive Bayes classifier selects the most effective method considering inferred weather states and the system makes a decision using the rules. We collected real weather data for the experiments and the average accuracy of the proposed method is 93.9%. In addition, comparing the photovoltaic efficiency with the pinhole camera system results in improved performance of about 16.58%.

• Microbiology and Biotechnology Letters
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• v.41 no.2
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• pp.207-214
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• 2013

A concerted effort to develop alternative forms of energy is underway due to fossil fuel shortages and its deleterious effects. Recently, bioenergy from microalgae has gained prominence and the use of municipal wastewater as a low cost alternative for a nutrient source has significant advantages. In this study, we have employed municipal wastewater directly after primary treatment (primary settling basin) in a small scale raceway pond (SSRP) for microalgal growth. Indigenous microalgae in the wastewater were encouraged to grow in the SSRP under optimal conditions. The mean removal efficiencies of TN, TP, and $NH_3-N$ after 6 days were 77.77%, 63.55%, and 89.02%, respectively. The average lipid content of the microalgae was 19.51% of dry cell weight, and linolenate and linoleate (18:n) were the predominant fatty acids. The 18S rRNA gene analysis and microscopic observations of the indigenous microalgae community revealed the presence of Chlorella vulgaris and Scenedesmus obliquus as the dominant microalgae. These results indicate that untreated municipal wastewater, serving as an excellent nitrogen and phosphate source for microalgal growth, could be treated using microalgae in open raceway ponds. Moreover, microalgal biomass could be further profitable by the extraction of biodiesel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.663-667
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• 2017

Fuel depletion and environmental problems due to the use of fossil fuels have been worsening of late, and the development of alternative energy sources is urgently required to address these problems. Among the alternative energy sources, wind energy is attracting much attention as a clean energy source, because it can be used unlimitedly without any pollutant emissions. In wind power generation, wind energy is converted to kinetic energy through rotor blades and this kinetic energy is converted to electric energy through generators. The design and manufacturing of the blades, which are the major parts of wind power generators, are very important, but South Korea still lacks the requisite basic data and key technologies and, therefore, has to import the blades from overseas. In this study, multi-layered blades capable of generating power at low wind speeds were applied to a small wind power generator and the output characteristics of the generator according to the wind speed and the number of blades were analyzed. As a result, at the maximum wind speed of 8m/s, the application of three blades achieved up to 33% and 18% higher generator output voltage, up to 33% and 15% higher generator output current, and up to 23% and 13% higher generator RPM than the application of one or two blades, respectively. In this study, the application of multi-layered blades to a small wind power generator was shown to improve the output characteristics of the generator and make the collection of electric energy possible even at low wind speeds.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.551-560
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• 2020

Recently, the offshore wind power generator market is expected to grow significantly because of increased energy demand, reduced dependence on fossil fuel-based power generation, and environmental regulations. Consequently, wind power generation is increasing worldwide, and several attempts have been made to utilize offshore wind power. Norway's Petroleum Safety Authority (PSA) requires a leg-structure design with a collision energy of 35 MJ owing to the event of a collision under operation conditions. In this study, the results of the numerical analysis of a wind turbine installation vessel subjected to ship collision were set such that the maximum collision energy that the leg could sustain was calculated and compared with the PSA requirements. The current leg design plan does not satisfy the required value of 35 MJ, and it is necessary to increase the section modulus by more than 200 % to satisfy the regulations, which is unfeasible in realistic leg design. Therefore, a collision energy standard based on a reasonable collision scenario should be established.

• Environmental and Resource Economics Review
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• v.16 no.1
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• pp.129-169
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• 2007

The purpose of this study is to experiment and simulate the newly-updated Second Generation Model for Korea (SGM-Korea). With the updated model, we tried to simulate effect of carbon tax on $CO_2$ emissions and other macroeconomic variables for Korea. The baseline data are compared with projected profiles by various scenarios to evaluate its performance. Our contribution in this study is to having up-graded the model from its earlier version by building new hybrid input-output table based on 2000 input-output and energy balanced tables. According to our estimation, total $CO_2$ emission in Korea has already increased in 2000 to about 1.86 times the 1990 figure. The level of carbon tax required for the current level of $CO_2$ emission to be reduced to the 1995 or 2000 level seems to be too high for Korean economy to bear. It is possible to find a reasonable level of carbon tax, however, if it can combine it with improvement of energy efficiency at the rate of 0.5% to 1% per year. For Korea to meet its obligation to reduce $CO_2$ emissions, therefore, it is imperative for her to improve energy efficiency as well as to develop alternative energy source reducing its dependence on fossil fuel.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.7
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• pp.461-468
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• 2014

Biochar is a carbon rich solid produced by the pyrolysis of biomass such as energy crops, forestry residues, and wood wastes. Biochar returned to soil is to mitigate climate change and the feedstock of wood wastes reduces fossil fuel consumption as well as disposal costs. This study was practiced to evaluate a biochar system by gasification in terms of global warming regarding the soil application of the produced biochar. Life cycle assessment methodology was used to analyze the environmental impacts of the system, and the functional unit was 1 tonne of wood wastes. The result shows that the biochar system by using wood wastes as feedstock produces 4.048E-01 $kgCO_2-eq$ from the pre-treatment process as chipping and drying, 4.579E-01 $kgCO_2-eq$ from the pyrolysis process, and 9.070E-02 $kgCO_2-eq$ from the spreading to agricultural land, therefore total 9.534E-01 $kgCO_2-eq$ are generated. About 252 kg of $CO_2$ is still stored in the produced biochar in soil after carbon offsetting of the system. Therefore, the net carbon of the system is -251 kg of $CO_2-eq$.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.111-115
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• 2005

The concentration of atmosphere carbon dioxide ($CO_2$) which is one of the major greenhouse gas, continues to rise by the increase in fossil fuel consumption, forest destruction and decrease of biological diversity, etc. In order to weaken the global warming, a reduction of $CO_2$ discharge to the atmosphere is required. The $CO_2$ ocean sequestration technology utilizes the intrinsic oceanic capacity of $CO_2$ absorption, diluting and/or dispersing the liquefied $CO_2$ in the deep ocean (>2,000 m). This geo-engineering approach is regarded as one of the occasions to mitigate the $CO_2$ concentration in the atmosphere. Some developed centuries such as Japan, USA, Norway, etc. have intensively carried out the projects on the research and development of $CO_2$ ocean sequestration since 1990s. There have been several approaches to develop the relative technological system to mitigate the increasing $CO_2$, however, there was no systematic and practical R&D programme in the $CO_2$ ocean sequestration. This paper has described the state of the art on the three optional methods of $CO_2$ sequestration, and compared with them in the aspect of the applicable possibility.