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307 result(s) for "Juhyun Lee"
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Tropical Cyclone Intensity Estimation Using Multi-Dimensional Convolutional Neural Networks from Geostationary Satellite Data
For a long time, researchers have tried to find a way to analyze tropical cyclone (TC) intensity in real-time. Since there is no standardized method for estimating TC intensity and the most widely used method is a manual algorithm using satellite-based cloud images, there is a bias that varies depending on the TC center and shape. In this study, we adopted convolutional neural networks (CNNs) which are part of a state-of-art approach that analyzes image patterns to estimate TC intensity by mimicking human cloud pattern recognition. Both two dimensional-CNN (2D-CNN) and three-dimensional-CNN (3D-CNN) were used to analyze the relationship between multi-spectral geostationary satellite images and TC intensity. Our best-optimized model produced a root mean squared error (RMSE) of 8.32 kts, resulting in better performance (~35%) than the existing model using the CNN-based approach with a single channel image. Moreover, we analyzed the characteristics of multi-spectral satellite-based TC images according to intensity using a heat map, which is one of the visualization means of CNNs. It shows that the stronger the intensity of the TC, the greater the influence of the TC center in the lower atmosphere. This is consistent with the results from the existing TC initialization method with numerical simulations based on dynamical TC models. Our study suggests the possibility that a deep learning approach can be used to interpret the behavior characteristics of TCs.
Bridging the gap between theory and practice in sustainable urban planning education through active learning with SDGs project assessment tool
Education for Sustainable Development (ESD) in higher education (HE) continues to struggle with bridging the theory–practice gap, especially in urban planning education, where students often lack the critical skills to holistically evaluate cities through a sustainability lens. This study investigates how the Sustainable Development Goals (SDG) Project Assessment Tool, developed by UN-Habitat to help urban planners align with the SDGs, can foster active learning and reflective practice in urban planning education, especially within a transnational context. This research was conducted as action research embedded in the postgraduate module “Sustainable Urban Planning Strategies” involving 88 students from five different academic programs. The module emphasizes applying sustainability principles to real-world planning practice, with the SDG tool integrated into both classroom activities and assessed coursework. To explore how such tools support experiential learning and critical reflection, data were collected through classroom observations, online surveys, and analysis of students’ reflective coursework, combining qualitative and quantitative methods. Findings reveal that the SDG tool enabled students to apply theoretical concepts to real-world planning challenges, while also prompting critical reflection and adaptation of the tool itself. Students proactively engaged with modifying the tool to address cultural, social, and contextual differences across cities. Importantly, disciplinary orientations influenced how students engaged with the tool, often prioritizing aspects aligned with their discipline, highlighting both the value and complexity of disciplinary diversity in implementing ESD. Overall, our study contributes to the underexplored area of sustainability evaluation tools in HE and establishes an evidence-based foundation for more integrated, experiential, and practice-oriented ESD that prepares students to address complex urban issues.
Cardiac tissue engineering: state-of-the-art methods and outlook
The purpose of this review is to assess the state-of-the-art fabrication methods, advances in genome editing, and the use of machine learning to shape the prospective growth in cardiac tissue engineering. Those interdisciplinary emerging innovations would move forward basic research in this field and their clinical applications. The long-entrenched challenges in this field could be addressed by novel 3-dimensional (3D) scaffold substrates for cardiomyocyte (CM) growth and maturation. Stem cell-based therapy through genome editing techniques can repair gene mutation, control better maturation of CMs or even reveal its molecular clock. Finally, machine learning and precision control for improvements of the construct fabrication process and optimization in tissue-specific clonal selections with an outlook of cardiac tissue engineering are also presented.
An Advanced Operational Approach for Tropical Cyclone Center Estimation Using Geostationary-Satellite-Based Water Vapor and Infrared Channels
Tropical cyclones (TCs) are destructive natural disasters. Accurate prediction and monitoring are important to mitigate the effects of natural disasters. Although remarkable efforts have been made to understand TCs, operational monitoring information still depends on the experience and knowledge of forecasters. In this study, a fully automated geostationary-satellite-based TC center estimation approach is proposed. The proposed approach consists of two improved methods: the setting of regions of interest (ROI) using a score matrix (SCM) and a TC center determination method using an enhanced logarithmic spiral band (LSB) and SCM. The former enables prescreening of the regions that may be misidentified as TC centers during the ROI setting step, and the latter contributes to the determination of an accurate TC center, considering the size and length of the TC rainband in relation to its intensity. Two schemes, schemes A and B, were examined depending on whether the forecasting data or real-time observations were used to determine the initial guess of the TC centers. For each scheme, two models were evaluated to discern whether SCM was combined with LSB for TC center determination. The results were investigated based on TC intensity and phase to determine the impact of TC structural characteristics on TC center determination. While both proposed models improved the detection performance over the existing approach, the best-performing model (i.e., LSB combined with SCM) achieved skill scores (SSs) of +17.4% and +20.8% for the two schemes. In particular, the model resulted in a significant improvement for strong TCs (categories 4 and 5), with SSs of +47.8% and +72.8% and +41.2% and +72.3% for schemes A and B, respectively. The research findings provide an improved understanding of the intensity- and phase-wise spatial characteristics of TCs, which contributes to objective TC center estimation.
Customizable, wireless and implantable neural probe design and fabrication via 3D printing
This Protocol Extension describes the low-cost production of rapidly customizable optical neural probes for in vivo optogenetics. We detail the use of a 3D printer to fabricate minimally invasive microscale inorganic light-emitting-diode-based neural probes that can control neural circuit activity in freely behaving animals, thus extending the scope of two previously published protocols describing the fabrication and implementation of optoelectronic devices for studying intact neural systems. The 3D-printing fabrication process does not require extensive training and eliminates the need for expensive materials, specialized cleanroom facilities and time-consuming microfabrication techniques typical of conventional manufacturing processes. As a result, the design of the probes can be quickly optimized, on the basis of experimental need, reducing the cost and turnaround for customization. For example, 3D-printed probes can be customized to target multiple brain regions or scaled up for use in large animal models. This protocol comprises three procedures: (1) probe fabrication, (2) wireless module preparation and (3) implantation for in vivo assays. For experienced researchers, neural probe and wireless module fabrication requires ~2 d, while implantation should take 30–60 min per animal. Time required for behavioral assays will vary depending on the experimental design and should include at least 5 d of animal handling before implantation of the probe, to familiarize each animal to their handler, thus reducing handling stress that may influence the result of the behavioral assays. The implementation of customized probes improves the flexibility in optogenetic experimental design and increases access to wireless probes for in vivo optogenetic research. This Protocol Extension describes the fabrication and implantation of 3D-printed neural probes for tethered or wireless optogenetics in freely moving rodents.
Exploring Potential R&D Collaboration Partners Using Embedding of Patent Graph
Rapid market change is one of the reasons for accelerating a technology lifecycle. Enterprises have socialized, externalized, combined, and internalized knowledge for their survival. However, the current era requires ambidextrous innovation through the diffusion of knowledge from enterprises. Accordingly, enterprises have discovered sustainable resources and increased market value through collaborations with research institutions and universities. Such collaborative activities effectively improve enterprise innovation, economic growth, and national competence. However, as such collaborations are conducted continuously and iteratively, their effect has gradually weakened. Therefore, we focus on exploring potential R&D collaboration partners through patents co-owned by enterprises, research institutions, and universities. The business pattern of co-applicants is extracted through a patent graph, and potential R&D collaboration partners are unearthed. In this paper, we propose a method of converting a co-applicant-based graph into a vector using representation learning. Our purpose is to explore potential R&D collaboration partners from the similarity between vectors. Compared to other methods, the proposed method contributes to discovering potential R&D collaboration partners based on organizational features. The following questions are considered in order to discover potential R&D partners in collaborative activities: Can information about co-applicants of patents satisfactorily explain R&D collaboration? Conversely, can potential R&D collaboration partners be discovered from co-applicants? To answer these questions, we conducted experiments using autonomous-driving-related patents. We verified that our proposed method can explore potential R&D collaboration partners with high accuracy through experiments.
A Study on the Calibrated Confidence of Text Classification Using a Variational Bayes
Recently, predictions based on big data have become more successful. In fact, research using images or text can make a long-imagined future come true. However, the data often contain a lot of noise, or the model does not account for the data, which increases uncertainty. Moreover, the gap between accuracy and likelihood is widening in modern predictive models. This gap may increase the uncertainty of predictions. In particular, applications such as self-driving cars and healthcare have problems that can be directly threatened by these uncertainties. Previous studies have proposed methods for reducing uncertainty in applications using images or signals. However, although studies that use natural language processing are being actively conducted, there remains insufficient discussion about uncertainty in text classification. Therefore, we propose a method that uses Variational Bayes to reduce the difference between accuracy and likelihood in text classification. This paper conducts an experiment using patent data in the field of technology management to confirm the proposed method’s practical applicability. As a result of the experiment, the calibrated confidence in the model was very small, from a minimum of 0.02 to a maximum of 0.04. Furthermore, through statistical tests, we proved that the proposed method within the significance level of 0.05 was more effective at calibrating the confidence than before.
A Novel Framework of Detecting Convective Initiation Combining Automated Sampling, Machine Learning, and Repeated Model Tuning from Geostationary Satellite Data
This paper proposes a complete framework of a machine learning-based model that detects convective initiation (CI) from geostationary meteorological satellite data. The suggested framework consists of three main processes: (1) An automated sampling tool; (2) machine learning-based CI detection modelling; (3) repeated model tuning through validation. In this study, the automated sampling tool was able to track the CI objects iteratively, even without ancillary data such as an atmospheric motion vector (AMV). The collected samples were used to train the machine learning model for CI detection. Random forest (RF) was used to classify the CI and non-CI. To enhance the advantages of the machine learning approach, we adopted model tuning to iteratively update the training dataset from each validation result by adding hits and misses to the CI samples, and false alarms and correct negatives to the non-CI samples. Using 12 interest fields from the Himawari-8 Advanced Himawari Imager (AHI) over the Korean Peninsula, this simple and intuitive tuning process increased the overall probability of detection (POD) from 0.79 to 0.82 and decreased the overall false alarm rate (FAR) from 0.46 to 0.37 with around 40 min of the lead-time. Amongst the 12 interest fields, T b (11.2) µm was identified as the most significant predictor in the RF model, followed by T b (8.6—11.2) µm, and T b (6.2–7.3) µm. The effect of model tuning on the CI detection performance was also analyzed using spatiotemporal validation maps. By automatically collecting and updating the machine learning training dataset, the suggested framework is expected to help the maintenance of the CI detection model from an operational perspective.
A method to quantify mechanobiologic forces during zebrafish cardiac development using 4-D light sheet imaging and computational modeling
Blood flow and mechanical forces in the ventricle are implicated in cardiac development and trabeculation. However, the mechanisms of mechanotransduction remain elusive. This is due in part to the challenges associated with accurately quantifying mechanical forces in the developing heart. We present a novel computational framework to simulate cardiac hemodynamics in developing zebrafish embryos by coupling 4-D light sheet imaging with a stabilized finite element flow solver, and extract time-dependent mechanical stimuli data. We employ deformable image registration methods to segment the motion of the ventricle from high resolution 4-D light sheet image data. This results in a robust and efficient workflow, as segmentation need only be performed at one cardiac phase, while wall position in the other cardiac phases is found by image registration. Ventricular hemodynamics are then quantified by numerically solving the Navier-Stokes equations in the moving wall domain with our validated flow solver. We demonstrate the applicability of the workflow in wild type zebrafish and three treated fish types that disrupt trabeculation: (a) chemical treatment using AG1478, an ErbB2 signaling inhibitor that inhibits proliferation and differentiation of cardiac trabeculation; (b) injection of gata1a morpholino oligomer (gata1aMO) suppressing hematopoiesis and resulting in attenuated trabeculation; (c) weak-atriumm58 mutant (wea) with inhibited atrial contraction leading to a highly undeveloped ventricle and poor cardiac function. Our simulations reveal elevated wall shear stress (WSS) in wild type and AG1478 compared to gata1aMO and wea. High oscillatory shear index (OSI) in the grooves between trabeculae, compared to lower values on the ridges, in the wild type suggest oscillatory forces as a possible regulatory mechanism of cardiac trabeculation development. The framework has broad applicability for future cardiac developmental studies focused on quantitatively investigating the role of hemodynamic forces and mechanotransduction during morphogenesis.
Proformer: a hybrid macaron transformer model predicts expression values from promoter sequences
The breakthrough high-throughput measurement of the cis-regulatory activity of millions of randomly generated promoters provides an unprecedented opportunity to systematically decode the cis-regulatory logic that determines the expression values. We developed an end-to-end transformer encoder architecture named Proformer to predict the expression values from DNA sequences. Proformer used a Macaron-like Transformer encoder architecture, where two half-step feed forward (FFN) layers were placed at the beginning and the end of each encoder block, and a separable 1D convolution layer was inserted after the first FFN layer and in front of the multi-head attention layer. The sliding k -mers from one-hot encoded sequences were mapped onto a continuous embedding, combined with the learned positional embedding and strand embedding (forward strand vs. reverse complemented strand) as the sequence input. Moreover, Proformer introduced multiple expression heads with mask filling to prevent the transformer models from collapsing when training on relatively small amount of data. We empirically determined that this design had significantly better performance than the conventional design such as using the global pooling layer as the output layer for the regression task. These analyses support the notion that Proformer provides a novel method of learning and enhances our understanding of how cis-regulatory sequences determine the expression values.