• Progress in Medical Physics
• /
• v.32 no.4
• /
• pp.172-178
• /
• 2021

Purpose: This study aimed to develop a deep learning architecture combining two task models to generate synthetic computed tomography (sCT) images from low-tesla magnetic resonance (MR) images to improve metallic marker visibility. Methods: Twenty-three patients with cervical cancer treated with intracavitary radiotherapy (ICR) were retrospectively enrolled, and images were acquired using both a computed tomography (CT) scanner and a low-tesla MR machine. The CT images were aligned to the corresponding MR images using a deformable registration, and the metallic dummy source markers were delineated using threshold-based segmentation followed by manual modification. The deformed CT (dCT), MR, and segmentation mask pairs were used for training and testing. The sCT generation model has a cascaded three-dimensional (3D) U-Net-based architecture that converts MR images to CT images and segments the metallic marker. The performance of the model was evaluated with intensity-based comparison metrics. Results: The proposed model with segmentation loss outperformed the 3D U-Net in terms of errors between the sCT and dCT. The structural similarity score difference was not significant. Conclusions: Our study shows the two-task-based deep learning models for generating the sCT images using low-tesla MR images for 3D ICR. This approach will be useful to the MR-only workflow in high-dose-rate brachytherapy.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.121-122
• /
• 2002

The main principle of radiation therapy is to deliver optimum dose to tumor to increase tumor cure probability while minimizing dose to critical normal structure to reduce complications. RTP system is required for proper dose plan in radiation therapy treatment. The main goal of this research is to develop dose model for photon, electron, and brachytherapy, and to display dose distribution on patient images with optimum process. The main items developed in this research includes: (l) user requirements and quality control; analysis of user requirement in RTP, networking between RTP and relevant equipment, quality control using phantom for clinical application (2) dose model in RTP; photon, electron, brachytherapy, modifying dose model (3) image processing and 3D visualization; 2D image processing, auto contouring, image reconstruction, 3D visualization (4) object modeling and graphic user interface; development of total software structure, step-by-step planning procedure, window design and user-interface. Our final product show strong capability for routine and advance RTP planning.

• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.36.2-36.2
• /
• 2020

Intensive Monitoring Survey of Nearby Galaxies (IMSNG) has been managed over 6 years. It aimed to constrain the progenitor system and explosion mechanism of SNe by detection of very early signal from shock heated emission. We have conducted monitoring observation of nearby bright galaxies those were carefully selected using global network of 1-m class telescopes. More than 20 SNe have occured in our target fields. As One of result of the survey, we present light curve analysis of type Ia SN 2018kp, which was discovered in NGC 3367. Based on photometric analysis, we calculated explosion parameters and set constraints of physical conditions of this supernova. We compared the results with theoretical model progenitor systems to find out which scenario is the most fitted to SN 2018kp case. Moreover, we estimate the distance to the galaxy and look into the relation between SNe and galactic physical parameters.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.557-562
• /
• 2004

For constructing virtual environment it is more natural to model object as deformable body than as rigid body. High accuracy of simulation of model and low-latency computational cost for real-time simulation should be guaranteed. We pre-compute Green function through finite element analysis of deformable body and it is possible to simulate deformation of body in real-time environment using Capacitance Matrix Algorithm. Also, the capacitance matrix algorithm enables to construct the haptic rendering which serves the reaction force through a haptic device. The Newmark scheme is used for the more realistic haptic rendering and dynamic simulation in real-time.

• Nuclear Engineering and Technology
• /
• v.54 no.5
• /
• pp.1929-1934
• /
• 2022

Besides recent progresses in the physics-based modelling of fission gas and helium behaviour, the scarcity of experimental data concerning their combined behaviour (i.e., cocktail) hinders further model developments. For this reason, in this work, we propose a modelling methodology aimed at providing recommendations for accelerated experimental investigations. By exploring a wide range of annealing temperatures and cocktail compositions with a physics-based modelling approach we identify the most interesting conditions to be targeted by future experiments. To corroborate the recommendations arising from the proposed methodology, we include a sensitivity analysis quantifying the impact of the model parameters on fission gas and helium release, in conditions representative of high and low burnup.

• Bulletin of the Korean Space Science Society
• /
• 2003.10a
• /
• pp.39-39
• /
• 2003

The plasmaspheric region shows relatively strong longitudinal asymmetry in the sense that the location of the plasmapause and the density distribution significantly vary with respect to local time, and this asymmetry effect has been neglected in previous magnetospheric ULF wave studies. In this study, we numerically examine the MHD wave properties of field line resonances (FLRs) and Pi2 pulsations when the inner magnetosphere is assumed to be asymmetric. We use the dipole magnetic field model, but our density model is based on. observational data from the IMAGE satellite. We assume an impulsive input in the magnetotail, which can be associated with a substorm onset. Our results suggest that local FLRs appear in both the radial and azimuthal oscillations owing to the asymmetry. Plasmaspheric Pi2 signals appear in the compressional component, but they are more strongly affected by ambient plasmaspheric structure than the FLRs. We compare our results with the observational data of Pi2 events.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.2
• /
• pp.72.3-73
• /
• 2021

Baryon Acoustic Oscillations (BAO) are caused by acoustic density waves in the early universe and act as a standard ruler in the clustering pattern of galaxies in the late Universe. Measuring the BAO feature in the 2-point correlation function of a sample of galaxies allows us to estimate cosmological distances to the galaxies mean redshift, , which is important for testing and constraining the cosmology model. The BAO feature is also expected to appear in the higher order statistics. In this work we measure the generalized spatial N-point point correlation functions up to 4th order. We made measurements of the 2, 3, and 4-point correlation functions in the SDSS-III DR12 CMASS data, comprising of 777,202 galaxies. The errors and covariances matrices were estimated from 500 mock catalogues. We created a theoretical model for these statistics by measuring the N-point functions in halo catalogues produced by the approximate Lagrangian perturbation theory based simulation code, PINOCCHIO. We created simulations using initial conditions with and without the BAO feature. We find that the BAO is detected to high significance up to the 4-point correlation function.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.943-946
• /
• 2008

Many works have been done to enable computer, as brain of robot, to learn color categorization, most of them rely on modeling of human color perception and mathematical complexities. This paper aims at developing the innate ability of the computer to learn the human-like color categorization.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.11 no.3
• /
• pp.153-161
• /
• 2011

In this work, we report the physics-based SPICE model of amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) and demonstrate the SPICE simulation of amorphous InGaZnO (a-IGZO) TFT inverter by using Verilog-A. As key physical parameter, subgap density-of-states (DOS) is extracted and used for calculating the electric potential, carrier density, and mobility along the depth direction of active thin-film. It is confirmed that the proposed DOS-based SPICE model can successfully reproduce the voltage transfer characteristic of a-IGZO inverter as well as the measured I-V characteristics of a-IGZO TFTs within the average error of 6% at $V_{DD}$=20 V.

• Advances in aircraft and spacecraft science
• /
• v.7 no.6
• /
• pp.475-493
• /
• 2020

This paper is focused on the characterization of the thermomechanical properties of semicrystalline poly-ether-ether-ketone (PEKK) and of carbon fiberreinforced thermoplastic based laminated composites (C/PEKK) below and above the glass transition temperature (T_g). Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and tensile tests are carried out on both pure PEKK polymer and [(±45)₂, +45]_s C/PEKK composite samples, showing a significant similarity in behavior. The employment of a simple micromechanical model confirms that the mechanical and physical behavior of the polymer and that of the matrix in the composite are similar.