• Earthquakes and Structures
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• v.16 no.6
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• pp.691-704
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• 2019

This study simulates the responses of large-scale bridge piers under pseudo-dynamic tests to investigate the performance of four types of numerical models that consider the nonlinear behavior of the pier and the rocking behavior of the footing. In the models, beam-column elements with plastic hinges are used for the pier, two types of foundation models (rotational spring and distributed spring models) are adopted for the footing behavior, and two types of viscous damping models (Rayleigh and dashpot models) are applied for energy dissipation. Results show that the nonlinear pier model combined with the distributed spring-dashpot foundation model can reasonably capture the behavior of the piers in the tests. Although the commonly used rotational spring foundation model adopts a nonlinear moment-rotation property that reflects the effect of footing uplift, it cannot suitably simulate the hysteretic moment-rotation response of the footing in the dynamic analysis once the footing uplifts. In addition, the piers are susceptible to cracking damage under strong seismic loading and the induced plastic response can provide contribution to earthquake energy dissipation.

• Journal of Wind Energy
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• v.2 no.1
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• pp.61-67
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• 2011

In the present study, numerical unsteady simulations of the NREL Phase VI wind turbine in downwind operation conditions were conducted to investigate rotor-tower interaction. The calculations were performed using an unstructured mesh, incompressible Reynolds-averaged Navier-Stokes flow solver. To capture the unsteady effects associated with the tower shadow between the rotor blades and the tower, the wind turbine was modelled including the rotor, tower, hub, and nacelle. The present results generally showed good agreements with available experimental data. At the lowest wind speed, the pressure distribution was characterized by a complete collapse of the suction peak on the blade when the blade passes through the tower wake. It was found that unsteady effects play a significant role in the response of the blades.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.343-347
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• 2011

Due to the strong dependence on fossil fuels within the history of human progress, it leads to disaster of the whole world like flood, shortage of water and extinction of the species. In order to curb carbon dioxide emissions, many technologies are being developed. Among them, porous carbon materials have important advantages over other absorbent, such as high surface area, thermal and chemical resistance, low cost, various pore distribution and low energy requirement for their regeneration. Carbon capture and storage (CCS) has attracted the significant research efforts for reducing green house gas emission using several absorbent and process. Moreover, the absorbent are used for the separation of bio mass gas that contains methane which is considered a promising fuel as new green energy resource. In this review, we summarized the recent studies and trend about the porous carbon materials for CCS as well as separation from the biogas.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.59-71
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• 2023

Carbon capture, and storage (CCS) is important for the reduction of greenhouse gases and achieving carbon neutrality. CCS focuses on storing captured CO₂ permanently in underground reservoirs. CO₂-enhanced oil recovery (CO₂-EOR) is one form of CCS, where CO₂ is injected into the underground to enhance oil recovery. CO₂-EOR not only aids in the extraction of residual oil but also contributes to carbon neutrality by storing CO₂ underground continuously. CO₂-EOR can be classified into miscible and immiscible methods, with the CO₂-water alternating gas (CO₂-WAG) technique being a representative approach within the miscible method. In CO₂-WAG, water and CO₂ are alternately injected into the reservoir, enabling oil production and CO₂ storage. The WAG method allows for controlling the breakthrough of injection fluids, providing advantages in oil recovery. It also induces hysteresis in relative permeability during the injection and production process, expanding the amount of trapped CO₂. In this study, the effects of enhancing oil recovery and storing CO₂ underground during CO₂-EOR were presented. Additionally, cases of CO₂-EOR application in relation to CCS were introduced.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.617-625
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• 2012

This study examines the current status and policy development of Carbon Dioxide Capture and Storage(CCS), which is a technology to mitigate climate change, in Korea and foreign countries. It also analyzes IEA CCS regulatory framework as a guideline and provides limitations and implications for marine geological storage in the Republic of Korea. Although CCS master plan is established at national level, related laws are not amended and detailed polices are not yet provided. Established 'Intergovernmental CCS committee' lacks its cooperative mechanism and flexibility. Only limited and segmented economic analyses are performed and funding for large scale of CCS project is not secured. In addition, information sharing is limited and public awareness activities are insufficient. Therefore, this paper provides some policy suggestions on establishing a legal framework based on the 'Marine Environmental Management Act', strengthening the role of intergovernmental CCS committee, conducting CCS economic analysis based on various scenarios, providing economic incentives and public participation strategies, and establishing a specialized agency for information sharing.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.539-546
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• 2019

Global warming has mentioned as one of the international problems and these researches have conducted. Carbon Capture, Utilization and Storage (CCUS) technology has improved due to increasing importance of reducing emission of carbon dioxide. Among of various CCUS technologies, mineral carbonation can converted $CO_2$ into high-cost materials with low energy. Existing researches has been used ions extracted solid wastes for mineral carbonation but the procedure is complicated. However, the procedure using seawater is simple because it contained high concentration of metal cation. This research is a basic study using seawater-based wastewater for mineral carbonation. 3 M Monoethanolamine (MEA) was used as $CO_2$ absorbent. Making various concentrations of seawater solution, simulated seawater powder was used. Precipitated metal carbonate salts were produced by mixing seawater solutions and $rich-CO_2$ absorbent solution. They were analyzed by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Thermogravimetric Analysis (TGA) and studied characteristic of producing precipitated metal carbonate and possibility of reusing absorbent.

• Journal of Hydrogen and New Energy
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• v.24 no.6
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• pp.535-542
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• 2013

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor using bed inserts, effect of bed insert geometry on CO conversion of WGS catalyst was measured and investigated. Small scale fluidized bed reactor was used as experimental apparatus and tablet shaped WGS catalyst and sand particle were used as bed materials. The cylinder type and the spring type bed inserts were used to hold the WGS catalysts. The CO conversion of WGS catalyst with the change of steam/CO ratio was determined based on the exit gas analysis. Moreover, gas flow direction was confirmed by bed pressure drop measurement for each case. The measured CO conversion using the bed inserts showed high value comparable to previous results even though at low catalyst content. Most of input gas flowed through the bed center side when we charged tablet type catalyst into the cylinder type bed insert and this can cause low $CO_2$ capture efficiency because the possibility of contact between input gas and $CO_2$ absorbent is low in this case. However, the spring type bed insert showed good reactivity and good distribution of gas, and therefore, the spring type bed insert was selected as the best bed insert for SEWGS process.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.1
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• pp.83-90
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• 2017

The pyroprocessing of spent nuclear fuel generates LiCl-KCl eutectic waste salt containing radioactive rare earth nuclides. It is necessary to develop a simple process for the treatment of LiCl-KCl eutectic waste in a hot-cell facility. In this study, capture and solidification of a rare earth nuclide (Nd) in LiCl-KCl eutectic salt using an inorganic composite with a $Li_2O-Al_2O_3-SiO_2-B_2O_3$ system was conducted to simplify the existing separation and solidification process of rare earth nuclides in LiCl-KCl eutectic waste salt from the pyroprocessing of spent nuclear fuel. More than 98wt% of Nd in LiCl-KCl eutectic salt was captured when the mass ratio of the composite was 0.67 over $NdCl_3$ in the eutectic salt. The content of $Nd_2O_3$ in the Nd captured-composite reached about 50wt%, and this composite was directly fabricated into a homogeneous and chemical resistant glass waste in a monolithic form. These results will be utilized in designing a process to simplify the existing separation and solidification process.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.150-163
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• 2015

Gasification technology is one of the representative next-generation fossil fuel utilization technologies, converting low grade fossil fuels such as coal, heavy residue oil, pet-coke into highly clean and efficient energy sources. Accordingly, related market demand for gasification technology is ever increasing steadily and rapidly. A few years ago, conventional pulverized coal utilization technology had an edge over the gasification technology but the most significant technical barrier of limited capacity and availability has been largely overcome nowadays. Futhermore, it will be more competitive in the future with the advancement of related technologies such as gas turbine, ion transfer membrane and so on. China has recently completed a commercialization-capable large-scale coal gasification technology for its domestic market expansion and foreign export, rapidly becoming a newcomer in the field and competing with existing US and EU technical leadership at comparable terms. Techno-economic aspect deserves intensive attention and steady R&D efforts need to continue in organized, considering that gasification technology is quite attractive combined with $CO_2$ capture process and coal to SNG plant is economically viable in Korea where natural gas is very expensive. In the present paper, recent technology development and commercialization trend of many leading companies with coal gasification expertise have been reviewed with significant portion of literature cited from the recently held '2014 Gasification Technology Conference'.

• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.356-367
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• 2018

A series of tests dedicated to station blackout (SBO) accident scenarios have been recently performed at the $Prim{\ddot{a}}rkreislauf-Versuchsanlage$ (primary coolant loop test facility; PKL) facility in the framework of the OECD/NEA PKL-3 project. These investigations address current safety issues related to beyond design basis accident transients with significant core heat up. This work presents a detailed analysis using the best estimate thermal-hydraulic code TRACE (v5.0 Patch4) of different SBO scenarios conducted at the PKL facility; failures of high- and low-pressure safety injection systems together with steam generator (SG) feedwater supply are considered, thus calling for adequate accident management actions and timely implementation of alternative emergency cooling procedures to prevent core meltdown. The presented analysis evaluates the capability of the applied TRACE model of the PKL facility to correctly capture the sequences of events in the different SBO scenarios, namely the SBO tests H2.1, H2.2 run 1 and H2.2 run 2, including symmetric or asymmetric secondary side depressurization, primary side depressurization, accumulator (ACC) injection in the cold legs and secondary side feeding with mobile pump and/or primary side emergency core coolant injection from the fuel pool cooling pump. This study is focused specifically on the prediction of the core exit temperature, which drives the execution of the most relevant accident management actions. This work presents, in particular, the key improvements made to the TRACE model that helped to improve the code predictions, including the modeling of dynamical heat losses, the nodalization of SGs' heat exchanger tubes and the ACCs. Another relevant aspect of this work is to evaluate how well the model simulations of the three different scenarios qualitatively and quantitatively capture the trends and results exhibited by the actual experiments. For instance, how the number of SGs considered for secondary side depressurization affects the heat transfer from primary side; how the discharge capacity of the pressurizer relief valve affects the dynamics of the transient; how ACC initial pressure and nitrogen release affect the grace time between ACC injection and subsequent core heat up; and how well the alternative feeding modes of the secondary and/or primary side with mobile injection pumps affect core quenching and ensure stable long-term core cooling under controlled boiling conditions.