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Into the unknown part of the human limb dynamics identification using a robot
No full textDepartment of Mechanical Engineeringclos
Evaluating ground motion models and spectrum decay parameter (??) for Korea
No full textDepartment of Urban and Environmental Engineering (Disaster Management Engineering)The Korean Peninsula was previously regarded as a stable continental region (SCR), but the sudden earthquake, with a moment magnitude (M) 5.4, occurred on 12 September 2016 at Gyeongju. After a year, M5.5 Pohang earthquake was occurred on November 15, 2017. It is analyzed that the possibility of a large earthquake is latent, with the perception that the 2020 earthquake in Haenam, Jeollanam-do, and the 2021 earthquake in Seogwipo (M 4.8). Ground-motion models (GMMsinclude ground motion prediction equations, ground-motion relations, and attenuation relationships) are the key to the seismic hazard assessment analysis. For example, the U.S. National Seismic Hazard Maps (NSHMs), the foundation for seismic hazard assessment, have been adopted the Next Generation Attenuation (NGA) models for shallow crustal earthquakes in the active tectonic regions (NGA-West2) coordinated by the Pacific Earthquake Engineering Research Center (PEER) (Rezaeian et al. 2014). Although GMMs are developed a lot, some of them are overly complex and the developing parameters for each GMM are different from each other, so it is not easy to compare the GMMs. Therefore, finding the method to select appropriate GMM considering the regional characteristics for the target region is significant.
The high-frequency spectral decay parameter kappa (??) has emerged as an essential parameter in seismic studies and engineering applications due to its significant role in determining ground motion attenuation characteristics. Despite the extensive research conducted in various parts of the world to estimate and comprehend ?? and its inherent components, ??0 and the shear-wave velocity in the top 30 m of soil (VS30), there exists a research gap in the context of the Korean Peninsula. This study aims to bridge this gap by exploring the relationship between ??0 and VS30 in Korea, supplementing the limited regional research on the subject. The study leverages an extensive database of earthquake seismograms from various locations across Korea to estimate ?? values and analyze their variations with factors such as epicentral distance and site conditions. Furthermore, the study scrutinizes the influence of ??0, perceived as a site-specific component, on the amplification or seismic properties of the ground, with an emphasis on its applicability in Ground Motion Models. This research offers insights into the regional characteristics of ?? and paves the way for more accurate and region-specific seismic hazard assessments in Korea.clos
Reservoir computing for salt-and-pepper noise removal with a small dataset
Get PDFDepartment of Mathematical SciencesWe propose a reservoir computing inspiring neural network approach for salt-and-pepper noise removal. Despite the fact that reservoir computing was derived from RNNs dealing with sequential data and that images are not sequential data, our clever reservoir design has made it possible for the reservoir to process image data through a nonlinear image-specific forward operator replacing the linear operator of the multiplication by a randomly chosen input weight matrix. There are two essential advantages of the proposed method. One is that it takes only a small amount of training data as many as a few hundreds of 24??24 images and outperforms most analytic or machine-learning based denoising models for saltand-pepper noise unlike most neural networks requiring a large amount of training data for good results to avoid overfitting, if not the best. Another is that the reconstruction is completely parallel, in that noisy pixels do not communicate with each other, and hence, noise in different pixels can be removed in parallel. Recursive reservoir architecture is also discussed to further improve the reconstruction quality, confirmed by various numerical simulations.clos
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No full textSchool of Energy and Chemical Engineering (Energy Engineering)clos
Approaching a reversible oxygen redox in high-energy Li-ion cathode materials by integrating experimental and computational study
No full textSchool of Energy and Chemical Engineering (Energy Engineering (Battery Science and Technology))clos
Investigation of the Degradation Mechanism and Dopant Selection Process of Mn-rich Olivine Cathode Materials (LiMnxFe1-xPO4)
No full textSchool of Energy and Chemical Engineering (Energy Engineering (Battery Science and Technology))clos
Development Heterogeneous Pd/C3N4 Catalysts for Formic Acid/Formate Cycle for CO2 Hydrogenation and Hydrogen Carrier
No full textSchool of Energy and Chemical Engineering (Chemical Engineering)clos
Characterization of thermotolerant Cupriavidus cauae PHS1 for production of polyhydroxyalkanoates
No full textSchool of Energy and Chemical Engineering (Chemical Engineering)clos
Leveraging 2D Masked Reconstruction for Domain Adaptation of 3D Pose Estimation
No full textGraduate School of Artificial Intelligenceclos
Component-Level Mitigation Solution and System-Level Analysis Method of High-Voltage Transient ESD Event
Get PDFDepartment of Electrical EngineeringElectrostatic discharge (ESD) is a significant phenomenon in the field of electromagnetic compatibility (EMC) that causes critical issues in the reliability and functionality of electronic devices and systems. ESD events can be classified based on the occurring environment and conditions, and the methods to address related issues vary accordingly. The two main classifications are component-level ESD events and system-level ESD events. Component-level ESD events primarily occur during repetitive and predictable stages of electronic component and product manufacturing processes. These events can be effectively addressed by eliminating the ESD hazards themselves. On the other hand, system-level ESD events are characterized by their irregular and unpredictable occurrence during the operation of electronic devices and systems. To address issues related to system-level ESD events, it is necessary to enhance ESD robustness of the system. This thesis covers research on various aspects of the ESD that encompass both component-level events and system-level events.
In electronic device manufacturing process, ionizers are commonly used to effectively eliminate static charges. Among diverse ionizers, corona ionizers utilizing a high-voltage source are widely preferred for their easy installation and safety. However, the corona ionizers may induce electric overstress (EOS) to sensitive electronic devices. Also, regular maintenance is necessary to prevent particle accumulation on corona ionizers, which can interfere with their performance and lead to ESD failures. In this thesis, a novel low-voltage microwave plasma ionizer is proposed and analyzed to address the critical limitations associated with the EOS risk and particle fuzzballs in the corona ionizers.
To evaluate the system-level ESD immunity of electronic products, researchers and manufacturers conduct ESD immunity tests according to international standards such as IEC 61000-4-2 and ISO 10605 for general and automotive electronic devices, respectively. However, the process of design iteration and troubleshooting to improve the ESD immunity of novel electronic devices in this test setup are time consuming and costly. To solve this problem, many studies have been conducted to predict ESD immunity by computing the system-level ESD noise in the test setup. However, the prediction of the automotive system-level ESD immunity is very difficult because the automotive ESD test setup in ISO 10605 contains complex and large structures, requiring significant computational memory and time. In this thesis, an accurate and efficient method for computing system-level ESD noise waveforms in the ISO 10605 standard using the decomposition method and split-domain approach is proposed and validated.
While the standards related to the ESD immunity test primarily address ESD scenarios involving a charged human body, it is also important to consider other objects that may act as ESD sources, which can be charged with high potential. For example, in areas with low relative humidity, such as deserts, automotive parts can be damaged or malfunction if they come into contact with a charged dust cleaner during cleaning operations. In this thesis, an ESD model of a dust cleaner is proposed and the ESD failure of an automobile headlamp is analyzed using the proposed ESD model.clos