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Fully soft electronics with enhanced interfacial contact between semiconductor and conductor for future wearable applications
No full textHigh fidelity transient solver in STREAM based on multigroup coarse-mesh finite difference method
No full textThis study incorporates a high-fidelity transient analysis solver based on multigroup CMFD in the MOC code STREAM. Transport modeling with heterogeneous geometries of the reactor core increases computational cost in terms of memory and time, whereas the multigroup CMFD reduces the computational cost. The reactor condition does not change at every time step, which is a vital point for the utilization of CMFD. CMFD correction factors are updated from the transport solution whenever the reactor core condition changes, and the simulation continues until the end. The transport solution is adjusted once CMFD achieves the solution. The flux-weighted method is used for rod decusping to update the partially inserted control rod cell material, which maintains the solution's stability. A smaller time-step size is needed to obtain an accurate solution, which increases the computational cost. The adaptive step-size control algorithm is robust for controlling the time step size. This algorithm is based on local errors and has the potential capability to accept or reject the solution. Several numerical problems are selected to analyze the performance and numerical accuracy of parallel computing, rod decusping, and adaptive time step control. Lastly, a typical pressurized LWR was chosen to study the rodejection accident. & COPY; 2023 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Carbon dioxide removal from the oceans: Carbon dioxide emission and techno-economic analyses of producing renewable synthetic methane
No full textThe capture of carbon dioxide from ocean water and utilizing the captured carbon as a stock for carbon-neutral renewable methane production may reduce a considerable amount of carbon in the atmosphere. However, given the lack of comprehensive analyses to reveal the potential, the examination proceeded through techno-economic and carbon dioxide emission analyses with several possible options of carbon dioxide extraction, location, electricity sources, and transport media. Through the economic analysis, the unit methane supply costs range from 3.5 to 7.5 $ kgCH4- 1 according to the different options, and the majority of the total cost is found to be the electrolysis for generating hydrogen. The results of the emission analysis indicate cumulative emissions of the considered pathways which are highly negative values of around -80,000 tonCO2 y-1 due to the utilization of carbon by extraction. However, the utilization of synthesized methane in the natural gas power plant makes the final cumulative emission amount become highly positive values of more than 70,000 tonCO2 y-1. Here, the required capture rates in the power plant are suggested for the respective pathways to achieve carbon neutrality. A capture rate of 54.44 % is required for the pathway using column and OTEC, while 77.62 % is required for the pathway using BPMED and PV. Thus, given that it could be verified that the suggested pathways are competitive in the environmental aspect if the carbon capture in the utilization plant is possible, which can take advantage of the rate less than the common existing rate, a significant reduction in the cost, especially the levelized cost of electricity, will be crucial for the pathways to attaining competitiveness in the economic aspect as well
Cementless ultra-high performance concrete (UHPC) using CaO- activated GGBFS and calcium formate as an accelerator
No full textThis study proposes an innovative approach to develop cementless ultra-high performance con-crete (UHPC) by activating ground granulated blast furnace slag (GGBFS) without an alkaline-activating solution. To develop cementless UHPC, calcium oxide (CaO) (5% by weight) was used to activate GGBFS, and calcium formate (CF) was used as an accelerator at concentrations rang -ing from 0 to 6 wt%. The results showed that CF significantly improved the mechanical proper -ties until 5 wt% and all the samples, including CF, exhibited a compressive strength of over 150 MPa. Uniaxial tensile tests revealed strain-hardening behavior, similar to typical cement-based UHPC. The addition of CF led to an increase in hydration products and pore size refine-ment, resulting in improved mechanical properties. The life cycle assessment results indicated that the developed UHPC mixture had nearly 70% lower CO2 emission than cement-based UHPC. The experimental results highlight the potential of this method for sustainable UHPC develop-ment
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No full textSchool of Business Administration (Management Engineering)clos
The Estimation of Earthquake Magnitudes using Pulse Durations and Amplitudes of Initial P-wave Seismograms in South Korea
No full textDepartment of Urban and Environmental Engineering (Disaster Management Engineering)clos
Laser Plasma Study through Simulation and Theory
Full text linkDepartment of PhysicsStimulated Raman Scattering (SRS) is a fascinating physical phenomenon that arises from the interaction between a plasma medium and high-energy laser radiation. It involves the transfer of laser energy to plasma waves, resulting in the generation of new waves and the scattering of the incident laser beam. SRS is an important phenomenon in laser plasma interaction, with various applications in fields such as laser fusion, particle acceleration, and high-energy-density physics. The SRS process begins when a high-intensity laser beam interacts with a plasma medium. The laser energy excites plasma waves, which can be longitudinal or transverse depending on the direction of the laser polarization. These waves then undergo a resonance process, where they interact with the plasma ions and transfer energy to them. As a result, new waves are generated, and the incident laser beam is scattered in a different direction. One of the most significant features of SRS is its threshold behavior. SRS only occurs when the laser intensity exceeds a certain threshold value. Below this value, the plasma waves cannot reach the resonance condition and do not transfer energy to the plasma ions. Above the threshold value, however, the plasma waves grow exponentially, leading to a rapid increase in the scattered light intensity. SRS has various applications in laser plasma interaction. In laser fusion, SRS can be a significant obstacle as it leads to the loss of laser energy and can damage the laser system. Researchers have developed various methods to mitigate SRS, such as using frequency conversion techniques, plasma shaping, and polarization smoothing. In particle acceleration, SRS can be used to generate high-energy electron beams. By controlling the laser intensity and plasma conditions, researchers can create plasma wakefields that accelerate charged particles to high energies. Plasma density diagnostics are crucial to understanding the laser plasma interaction process. One diagnostic method involves using a probe laser to measure the plasma density through the interaction with the plasma electrons. Other diagnostic methods include interferometry, Thomson scattering, and Langmuir probes. Raman scattering diagnostics are a powerful tool for measuring the plasma density in a wide range of applications. This technique relies on the inelastic scattering of light from the plasma, which results in a shift in the frequency of the scattered light. By measuring the frequency shift, researchers can determine the plasma density and gain insight into the plasma???s behavior. Overall, Raman scattering diagnostics are a powerful tool for measuring plasma density in a wide range of applications. These techniques can provide valuable insight into the plasma???s behavior and are essential for the development of advanced plasma technologies. Ongoing research continues to improve the sensitivity and accuracy of Raman scattering diagnostics, ensuring that these techniques remain at the forefront of plasma research. Plasma dipole oscillations are a type of collective motion that can occur in a plasma medium when it is excited by an external electromagnetic field. These oscillations result from the motion of the plasma electrons in response to the electromagnetic field, creating a dipole moment that oscillates at a characteristic frequency. Plasma dipole oscillations are an important phenomenon in plasma physics and have various applications, including as a radiation source for plasma diagnostics. Plasma dipole oscillations can also act as a radiation source for plasma diagnostics. When the dipole moment of the plasma oscillates, it generates electromagnetic radiation at the same frequency. This radiation can be in the THzband depending on the plasma parameters. This characteristics create new diagnostic method for plasma density. More easily usage of PDO method, we shot the laser pulse obliquely. The magnetization of the PDO induces the formation of three modes in gyrating electrons: the upper hybrid (H) mode, the right circular mode (R), and the left circular mode (L). The H-mode acts as a resonance point that prevents transmission to the vacuum, whereas X-modes can be transmitted through the plasma. The H-mode diminishes as the magnetic field increases, while X-modes become more prominent. This results in more energy being extracted from the PDO in the form of radiation. This effect is demonstrated by the effective flow, where in the weak field regime, electrons are well organized, resulting in effective longitudinal flow, while in the strong field regime, electron phases are randomized, and circular flows prevail, forming X-modes instead of H-mode.clos
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No full textDepartment of Biomedical Engineeringclos
Creative and practical solutions in genomic data analysis
No full textDepartment of Biomedical EngineeringToday, in practice, genomic data is rarely utilized to its full potential in clinical, academic, and research and development (R&D) sectors, owing to a variety of issues and technical limitations. This Ph.D. dissertation delves into two inherently distinct genomics studies with almost equal emphasis on the key findings and the limitations they encountered. The first part covers one of the pioneering studies in the history of Korean paleogenomics. The study presents eight whole genomes dated to Three Kingdoms period, seven of whom were obtained from, arguably, the most iconic funerary complex in the Three Kingdoms period Korea, the Daeseong-dong tumuli. This research has been an extensive collaborative effort among Korean Genomics Center (KOGIC), ancient DNA experts in Vienna University, four major museums in Korea, and two commercial entities, combining a variety of expertise. The ancient Korean study puts forward three important aspects: 1) Koreans during the Three Kingdoms period were not yet genetically homogeneous. 2) Jomon admixture was not explicitly endemic to the Japanese archipelago during the Three Kingdoms periodit is also found in Koreans from Gimhae locality, despite of being lost in modern Koreans 3) Genetic continuity from the Three Kingdoms period into modern Koreans is strong and can be observed by utilizing both genetic and phenotypic inference. While doing so, this study also presents potential solutions to address the ???blind spots??? in genomic analyses and highlights successful approaches in dealing with such technical limitations. One technical novelty presented in this study is the application of full facial profile prediction using forensic DNA-only markers. This is the first such case in paleogenomics having fully undergone peer-review process.
The second part of this dissertation provides a glimpse into methods and preliminary results on somatic mosaicism variant-calling in Korea10K genomes. This study instead of focusing on diseases, aims at observing peripheral blood mosaicism dynamics in a relatively healthy general population, the first large-scale study of its kind in Korea and beyond.clos