• Journal of the Korean institute of surface engineering
• /
• v.53 no.6
• /
• pp.330-342
• /
• 2020

Since the original report on ferroelectricity in Si-doped HfO2 in 2011, fluorite-structured ferroelectrics have attracted increasing interest due to their scalability, established deposition techniques including atomic layer deposition, and compatibility with the complementary-metal-oxide-semiconductor technology. Especially, the emerging fluorite-structured ferroelectrics are considered promising for the next-generation semiconductor devices such as storage class memories, memory-logic hybrid devices, and neuromorphic computing devices. For achieving the practical semiconductor devices, understanding polarization switching kinetics in fluorite-structured ferroelectrics is an urgent task. To understand the polarization switching kinetics and domain dynamics in this emerging ferroelectric materials, various classical models such as Kolmogorov-Avrami-Ishibashi model, nucleation limited switching model, inhomogeneous field mechanism model, and Du-Chen model have been applied to the fluorite-structured ferroelectrics. However, the polarization switching kinetics of fluorite-structured ferroelectrics are reported to be strongly affected by various nonideal factors such as nanoscale polymorphism, strong effect of defects such as oxygen vacancies and residual impurities, and polycrystallinity with a weak texture. Moreover, some important parameters for polarization switching kinetics and domain dynamics including activation field, domain wall velocity, and switching time distribution have been reported quantitatively different from conventional ferroelectrics such as perovskite-structured ferroelectrics. In this focused review, therefore, the polarization switching kinetics of fluorite-structured ferroelectrics are comprehensively reviewed based on the available literature.

• Smart Media Journal
• /
• v.9 no.4
• /
• pp.9-16
• /
• 2020

Recently, various studies are being conducted to integrate Image Segmentation into smart factory industries and autonomous driving fields. In particular, Image Segmentation systems using deep learning algorithms have been researched and developed enough to learn from large volumes of data with higher accuracy. In order to use image segmentation in the autonomous driving sector, sufficient amount of learning is needed with large amounts of data and the streaming environment that processes drivers' data in real time is important for the accuracy of safe operation through highways and child protection zones. Therefore, we proposed a novel DFCN algorithm that enhanced existing FCN algorithms that could be applied to various road environments, demonstrated that the performance of the DFCN algorithm improved 1.3% in terms of "loss" value compared to the previous FCN algorithms. Moreover, the proposed DFCN algorithm was applied to the existing U-Net algorithm to maintain the information of frequencies in the image to produce better results, resulting in a better performance than the classical FCN algorithm in the autonomous environment.

• Earthquakes and Structures
• /
• v.20 no.3
• /
• pp.353-364
• /
• 2021

Natural hazards like earthquakes, high winds, and tsunami are a threat all the time for multi-story structures. The environmental forces cannot be clogged but the structures can be prevented from these natural hazards by using protective systems. The structural control can be achieved by using protective systems like the passive, active, semi-active, and hybrid protective systems; but the semi-active protective system has gained importance because of its adaptability to the active systems and reliability of the passive systems. Therefore, a semi-active protective system for the earthquake forces has been adopted in this work. Magneto-Rheological (MR) damper is used in the structure as a semi-active protective system; which is connected to the current driver and proposed controller. The Proportional Integral Derivative (PID) controller and reliable PID controller are two proposed controllers, which will actuate the MR damper and the desired force is generated to mitigate the vibration of the structural response subjected to the earthquake. PID controller and reliable PID controller are designed and tuned using Ziegler-Nichols tuning technique along with the MR damper simulated in Simulink toolbox and MATLAB to obtain the reduced vibration in a three-story benchmark structure. The earthquake is considered to be uncertain; where the proposed control algorithm works well during the presence of earthquake; this paper considers robustness to provide satisfactory resilience against this uncertainty. In this work, two different earthquakes are considered like El-Centro and Northridge earthquakes for simulation with different controllers. In this paper performances of the structure with and without two controllers are compared and results are discussed.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.102-115
• /
• 2020

In this study, the SST k - ω turbulence model and the sliding mesh technology based on RANS method have been adopted to simulate the exciting force and hydrodynamic of a pump-jet propulsor in different oblique inflow angle (0°, 10°, 20°, 30°) and different advance ratio (J = 0.95, J = 1.18, J = 1.58).The fully structured grid and full channel model have been adopted to improved computational accuracy. The classical skewed marine propeller E779A with different advance ratio was carried out to verify the accuracy of the numerical simulation method. The grid independence was verified. The time-domain data of pump-jet propulsor exciting force including bearing force and fluctuating pressure in different working conditions was monitored, and then which was converted to frequency domain data by fast Fourier transform (FFT). The variation laws of bearing force and fluctuating pressure in different advance ratio and different oblique flow angle has been presented. The influence of the peak of pulsation pressure in different oblique flow angle and different advance ratio has been presented. The results show that the exciting force increases with the increase of the advance ratio, the closer which is to the rotor domain and the closer to the blades tip, the greater the variation of the pulsating pressure. At the same time, the exciting force decrease with the oblique flow angle increases. And the vertical and transverse forces will change more obviously, which is the main cause of the exciting force. In addition, the pressure distribution and the velocity distribution of rotor blades tip in different oblique flow angles has been investigated.

• Steel and Composite Structures
• /
• v.37 no.6
• /
• pp.711-731
• /
• 2020

This paper deals with free vibration of FG sandwich annular sector plates on Pasternak elastic foundation with different boundary conditions, based on the three-dimensional theory of elasticity. The plates with simply supported radial edges and arbitrary boundary conditions on their circular edges are considered. The influence of carbon nanotubes (CNTs) waviness, aspect ratio, internal pores and graphene platelets (GPLs) on the vibrational behavior of functionally graded nanocomposite sandwich plates is investigated in this research work. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness of upper and bottom layers of the sandwich sectorial plates and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. The core of structure is porous and the internal pores and graphene platelets (GPLs) are distributed in the matrix of core either uniformly or non-uniformly according to three different patterns. The elastic properties of the nanocomposite are obtained by employing Halpin-Tsai micromechanics model. A semi-analytic approach composed of 2D-Generalized Differential Quadrature Method (2D-GDQM) and series solution is adopted to solve the equations of motion. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. Some new results for the natural frequencies of the plate are prepared, which include the effects of elastic coefficients of foundation, boundary conditions, material and geometrical parameters. The new results can be used as benchmark solutions for future researches.

• Journal of the Korea Convergence Society
• /
• v.12 no.8
• /
• pp.47-53
• /
• 2021

With increasing interest in the 4th industrial revolution, data-driven scientific methodologies have developed. However, there are limitations of data collection in the real estate field of research. In addition, as the public becomes more knowledgeable about the real estate market, the qualitative sentiment comes to play a bigger role in the real estate market. Therefore, we propose a method to collect quantitative data that reflects sentiment using text mining and k-means algorithms, rather than the existing source data, and to predict the direction of housing index through artificial neural network learning based on the collected data. Data from 2012 to 2019 is set as the training period and 2020 as the prediction period. It is expected that this study will contribute to the utilization of scientific methods such as artificial neural networks rather than the use of the classical methodology for real estate market participants in their decision making process.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.8
• /
• pp.1060-1066
• /
• 2021

Recently, researches for quantum computers have been carried out in various fields. Quantum computers performs calculations by utilizing various phenomena and characteristics of quantum mechanics such as quantum entanglement and quantum superposition, thus it is a very complex calculation process compared to classical computers used in the past. In order to simulate a quantum computer, many factors and parameters of a quantum computer need to be analyzed, for example, error verification, optimization, and reliability verification. Therefore, it is necessary to visualize circuits that can intuitively simulate the configuration of the quantum computer components. In this paper, we present a novel visualization method for designing complex quantum computer system, and attempt to create a 3D visualization toolkit to deploy large circuits, provide help a new way to design large-scale quantum computing systems that can be built into future computing systems.

• The Journal of the Korea Contents Association
• /
• v.21 no.5
• /
• pp.824-836
• /
• 2021

In this study, the use of '心' letter used in classic Chinese book of 『Hwangjenaegyeog』 and its meaning was examined. In Chinese letters, '肉' is a sign that symbolizes the body. The letters '肝', '脾', '肺', and '腎' expressing the five human organs all contain the form of '肉'. So they don't cause semantic confusion. However, the Chinese letter that means heart and mind are written as '心'. As a result, it is difficult to understand the meaning of '心'. In addition, the contents of 『Hwangjenaegyeog』 cover various fields from disease to astronomy. For this reason, a total of 286 '心' letters used in it have various meanings. The results of this study are as follows. First, it means human heart. Second, it means the human chest. Third, it refers to mind. Fourth, it means a transcendent concept like spiritual enlightenment. Fifth, it refers to pericardium. Sixth, it refers to logical thought Seventh, it means center or core, and finally does constellation. in the eastern sky of ancient Asia. The results of this study are thought to be helpful in grasping the meaning of '心' in the classical literature as well as in 『hwangjenaegyeonglyeongchu』.

• Korean Journal of Remote Sensing
• /
• v.38 no.1
• /
• pp.21-32
• /
• 2022

The importance of the classical theme of how the Top-of-Atmosphere (TOA) and Top-of-Canopy (TOC) reflectance of high-resolution satellite images match the actual atmospheric reflectance and surface reflectance has been emphasized. Based on the Radiometric Calibration Network (RadCalNet) BTCN and BSCN data, this study compared the accuracy of TOA and TOC reflectance products of the currently available optical satellites, including KOMPSAT-3, WorldView-2, and Pléiades-1A image sets calculated using the absolute atmospheric correction function of the Orfeo Toolbox (OTB) tool. The comparison experiment used data in 2018 and 2019, and the Landsat-8 image sets from the same period were applied together. The experiment results showed that the product of TOA and TOC reflectance obtained from the three sets of images were highly consistent with RadCalNet data. It implies that any imagery may be applied when high-resolution reflectance products are required for a certain application. Meanwhile, the processed results of the OTB tool and those by the Apparent Reflection method of another tool for WorldView-2 images were nearly identical. However, in some cases, the reflectance products of Landsat-8 images provided by USGS sometimes showed relatively low consistency than those computed by the OTB tool, with the reference of RadCalNet BTCN and BSCN data. Continuous experiments on active vegetation areas in addition to the RadCalNet sites are necessary to obtain generalized results.

• Fashion & Textile Research Journal
• /
• v.23 no.6
• /
• pp.709-725
• /
• 2021

The study focused on the design features of Chanel and Fendi, directed by Carl Lagerfeld, creative director of Chanel and Fendi until his recent death. The range of the study was from the 2017 S/S Collection to the 2019 F/W Collection, which collected a total of 767 fashion photographs, including 483 Chanel, 284 Fendi, with tops, bottoms and dresses at VOGUE (https://www.vogue.com). According to the data analysis criteria organized based on prior research and related literature, it was classified in the order of form, color, material, pattern, decoration, fashion image, item and coordination, and content analysis was conducted based on statistical analysis. Overall, the design characteristics of the Chanel collection, directed by Karl Lagerfeld, were rectangle form, tone in tone coloring, combination of identical materials, geometric patterns, and classical images as the main design characteristics of the Chanel collection. The design characteristics shown in the Fendi collection directed by Karl Lagerfeld were rectangle form, tone in tone coloration, hard material combination, abstract pattern, and total coordination. Comparing the design features of Chanel and Fendi, directed by Karl Lagerfeld, is as follows. Chanel and Fendi's designs show a lot of rectangle form, tone-in-tone colors, hard-materials and combination of the same material.