• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.416-424
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• 2005

At present, the Korean electricity industry is undergoing restructuring and the Cost Based-generation Pool (CBP) market is being operated in preparation of a Two Way Bidding Pool (TWBP) market. In deregulated electricity industries, an integrated power market simulator is one of the tools that can be used by market participants and market operators analyzing market behaviors and studying market structures and market codes. In this regard, it is very important to develop an electricity market simulator that reflects market code providing a market operation mechanism. This paper presents the development of an integrated market simulator, called the Power Exchange Simulator (PEXSIM), which is designed to imitate the Korean electricity market considering the various features of the market operating mechanism such as uniform price and constrained on/off payment. The PEXSIM is developed in VB.NET and composed of five modules whose titles are M-SIM, P-SIM, O-SIM, T-SIM and G-SIM interfacing the Access database program. To verify the features and the performance of the PEXSIM, a small Two Way bidding market with a 12-bus system and a One Way bidding market for generator competition will be presented for the electricity market simulations using PEXSIM.

• Journal of Communications and Networks
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• 제7권4호
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• pp.438-449
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• 2005

In this paper, we describes the information-theoretic approaches to sensor selection and sensor placement in sensor net­works for target localization and tracking. We have developed a sensor selection heuristic to activate the most informative candidate sensor for collaborative target localization and tracking. The fusion of the observation by the selected sensor with the prior target location distribution yields nearly the greatest reduction of the entropy of the expected posterior target location distribution. Our sensor selection heuristic is computationally less complex and thus more suitable to sensor networks with moderate computing power than the mutual information sensor selection criteria. We have also developed a method to compute the posterior target location distribution with the minimum entropy that could be achieved by the fusion of observations of the sensor network with a given deployment geometry. We have found that the covariance matrix of the posterior target location distribution with the minimum entropy is consistent with the Cramer-Rao lower bound (CRB) of the target location estimate. Using the minimum entropy of the posterior target location distribution, we have characterized the effect of the sensor placement geometry on the localization accuracy.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2535-2542
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• 2020

To understand the fundamental parameters of Alvand tokamak, A Rogowski coil with an active integrator was designed and constructed. Considering the characteristics of the Alvand tokamak, the structural and electrical parameters affecting the sensor function, were designed. Calibration was performed directly in the presence of plasma. The sensor has a high resistance against interference of external magnetic fields. Plasma current was measured in various experiments. Based on the plasma current profile and loop voltage signal, the time evolution of plasma discharge was investigated and plasma behavior was analyzed. Alvand tokamak discharge was divided into several regions that represents different physical phenomena in the plasma. During the plasma discharge time, plasma had significant changes and its characteristic was not uniform. To understand the plasma behavior in each of the phases, the Rogowski sensor should have sufficient time resolution. The Rogowski sensor with a frequency up to 15 kHz was appropriate for this purpose.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2630-2637
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• 2020

The structure design of divertor Multi-Functional Maintenance Platform (MFMP) actuated by hydraulic system for China Fusion Engineering Test Reactor (CFETR) was introduced in this paper. The model of MFMP was established according to maintenance requirements. In this paper, Newton-Euler method and the improved virtual work principle were used, the equivalent driving force of each actuator was obtained through the equivalent Jacobian inverse matrix derived from velocity relationship among the components. The accuracy of the model was verified by ADAMS simulation. The stability control of the heavy-duty components driven by hydraulic cylinders based on Newton-Euler method and improved virtual work principle was established.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.491-500
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• 2012

The dissimilar metal joints welded between Ni-based alloy, Alloy 690 and low alloy steel, A533 Gr. B with Alloy 152 filler metal were characterized by using optical microscope, scanning electron microscope, transmission electron microscope, secondary ion mass spectrometry and 3-dimensional atom probe tomography. It was found that in the weld root region, the weld was divided into several regions including unmixed zone in Ni-base alloy, fusion boundary, and heat-affected zone in the low alloy steel. The result of nanostructural and nanochemical analyses in this study showed the non-homogeneous distribution of elements with higher Fe but lower Mn, Ni and Cr in A533 Gr. B compared with Alloy 152, and the precipitation of carbides near the fusion boundary.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1251-1260
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• 2019

The water-cooled WCLL blanket is one of the possible candidates for the blanket of the fusion power reactors. The plasma-facing first wall manufactured from the reduced-activation ferritic-martensitic steel Eurofer97 will be cooled with water at a typical pressurized water reactor (PWR) conditions. According to new estimates, the first wall will be exposed to peak heat fluxes up to $7MW/m^2$ while the maximum operated temperature of Eurofer97 is set to $550^{\circ}C$. The performed analysis shows the capability of the designed flat first wall concept to remove heat flux without exceeding the maximum Eurofer97 operating temperature only up to $0.75MW/m^2$. Several heat transfer enhancement methods (turbulator promoters), structural modifications, and variations of parameters were analysed. The effects of particular modifications on the wall temperature were evaluated using thermo-hydraulic three-dimensional numerical simulation. The analysis shows the negligible effect of the turbulators. By the combination of the proposed modifications, the permitted heat flux was increased up to $1.69MW/m^2$ only. The results indicate the necessity of the re-evaluation of the existing first wall concepts.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.51-73
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• 2023

Social media play a significant role in communicating information across the globe, connecting with loved ones, getting the news, communicating ideas, etc. However, a group of people uses social media to spread fake information, which has a bad impact on society. Therefore, minimizing fake news and its detection are the two primary challenges that need to be addressed. This paper presents a multi-modal deep learning technique to address the above challenges. The proposed modal can use and process visual and textual features. Therefore, it has the ability to detect fake information from visual and textual data. We used EfficientNetB0 and a sentence transformer, respectively, for detecting counterfeit images and for textural learning. Feature embedding is performed at individual channels, whilst fusion is done at the last classification layer. The late fusion is applied intentionally to mitigate the noisy data that are generated by multi-modalities. Extensive experiments are conducted, and performance is evaluated against state-of-the-art methods. Three real-world benchmark datasets, such as MediaEval (Twitter), Weibo, and Fakeddit, are used for experimentation. Result reveals that the proposed modal outperformed the state-of-the-art methods and achieved an accuracy of 86.48%, 82.50%, and 88.80%, respectively, for MediaEval (Twitter), Weibo, and Fakeddit datasets.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2678-2686
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• 2023

This work demonstrates the results of full-scale numerical experiments of a hybrid thorium-containing fuel plant operating in a state close to critical due to a controlled source of D-T neutrons. The proposed facility represented a level of generated power (~10-100 MW_t) in a small pilot. In this work, the simulation of the D-T neutron plasma source operation in conjunction with the facility blanket was performed. The fission of fuel nuclei and the formation of spatial-energy release were studied in this simulation, in pulsed and stationary modes of the facility operation. The optimization results of neutronic and fluid dynamics studies to level the emerging offsets of the radial energy formed in the volume of the facility multiplying part due to the pulsed operation of the D-T neutron plasma source were presented. The results will be useful in improving the power control-based subcriticality monitoring method in coupled systems of the "pulsed neutron source-subcritical fuel assembly" type.

• 한국인공지능학회지
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• 제11권4호
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• pp.1-8
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• 2023

In this paper, we propose a black ice detection platform framework using Convolutional Neural Networks (CNNs). To overcome black ice problem, we introduce a real-time based early warning platform using CNN-based architecture, and furthermore, in order to enhance the accuracy of black ice detection, we apply a multi-scale dilation convolution feature fusion (MsDC-FF) technique. Then, we establish a specialized experimental platform by using a comprehensive dataset of thermal road black ice images for a training and evaluation purpose. Experimental results of a real-time black ice detection platform show the better performance of our proposed network model compared to conventional image segmentation models. Our proposed platform have achieved real-time segmentation of road black ice areas by deploying a road black ice area segmentation network on the edge device Jetson Nano devices. This approach in parallel using multi-scale dilated convolutions with different dilation rates had faster segmentation speeds due to its smaller model parameters. The proposed MsCD-FF Net(2) model had the fastest segmentation speed at 5.53 frame per second (FPS). Thereby encouraging safe driving for motorists and providing decision support for road surface management in the road traffic monitoring department.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1490-1500
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• 2024

Helium-induced defect nucleation and accumulation in polycrystalline W and W0.5 wt%ZrC (W0.5ZrC) were studied in-situ using the transmission electron microscopy (TEM) combined with 40 keV He⁺ irradiation at 800 and 1000℃ at the maximum damage level of 1 dpa. Radiation-induced dislocation loops were not observed in the current study. W0.5ZrC was found to be less susceptible to irradiation damage in terms of helium bubble formation and growth, especially at lower temperature (800 ℃) when vacancies were less mobile. The ZrC particles present in the W matrix pin the forming helium bubbles via interaction between C atom and neighbouring W atom at vacancies. This reduces the capability of helium to trap a vacancy which is required to form the bubble core and, as a consequence, delays, the bubble nucleation. At 1000 ℃, significant bubble growth occurred in both materials and all the present bubbles transitioned from spherical to faceted shape, whereas at 800 ℃, the faceted helium bubble population was dominated in W.