• 한국한의학연구원논문집
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• 제2권1호
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• pp.40-70
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• 1996

In the literatual study on the cerebral vascular dementia, the results were as follows : 1. Cerebral vascular dementia is so called apoplectic dementia, because it almost occurs after apoplexy, the attack rate has gradually increased by increase of life, so it exert a harmful influence to geriatric diseases. 2. The etiological factors are summarized on deficiency in the heart, kidney, liver(心, 腎, 肝虛), pathogenic wind(豊) pathogenic fire(火) phlegm(痰) and stagnated blood(瘀血) in the oriental medicine, and multiple cerebral infarction, cerebral anemia, decrease of cerebral vascular flow are etiological factors in the occidental medicine. 3. The region of infarction and attack of cerebral vascular dementia have a close connection, and generally the cerebral vascular dementia easily occur in injury of white matter of brain. 4. Symptoms of cerebral vascular dementia are dysphasia, walking disorder, hemiplegia, sensory paralysis, disturbance of memory, judgement, calculation, emotion incontinence, speech impediment, silence or talkative, lower thinking ability and depersonalization, and symptoms are aggravated by stage. 5. Therapeutic herb medicines are Palpungsan(八風散), Baepungsan(排風散), Jinsaanshinhwan(辰砂安神丸), Sabacksan(四白散), Kanghwalyupungsan(姜活愈風散), Woohwangchungshimhwan(牛黃淸心丸), and they are used to dispelling pathogenic wind(祛風), soothe the nerves(安神), dispel pathogenic heat from lung, nourish the blood(淸肺養血).

• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.325-338
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• 2015

Experimental and numerical investigations were conducted to identify the wake characteristics downstream of two vane-type vortex generators over laminar flat plate boundary layer. Experimental study was carried out by using the stereoscopic particle image velocimetry. To describe the flow field around the vortex generator in detail, numerical study was performed. We considered two different planform shapes of vortex generator: triangular and rectangular shape. The height of the generator was chosen to be about the boundary layer thickness at the position of its installation. Two different lengths of the generator were chosen: two and five times the height. Wake measurements were carried out at three angles of attack for each configuration. Wake characteristics for each case such as overall vortical structure, vorticity distribution, and location of vortex center with downstream distance were obtained from the PIV data. Wake characteristics, as expected, were found to vary strongly with the geometry and angle of attack so that no general tendency could be deduced. Causes of this irregular tendency were explained by using the results of the numerical simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.3946-3965
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• 2018

Network anomaly detection in Software Defined Networking, especially the detection of DDoS attack, has been given great attention in recent years. It is convenient to build the Traffic Matrix from a global view in SDN. However, the monitoring and management of high-volume feature-rich traffic in large networks brings significant challenges. In this paper, we propose a moving window Principal Components Analysis based anomaly detection and mitigation approach to map data onto a low-dimensional subspace and keep monitoring the network state in real-time. Once the anomaly is detected, the controller will install the defense flow table rules onto the corresponding data plane switches to mitigate the attack. Furthermore, we evaluate our approach with experiments. The Receiver Operating Characteristic curves show that our approach performs well in both detection probability and false alarm probability compared with the entropy-based approach. In addition, the mitigation effect is impressive that our approach can prevent most of the attacking traffic. At last, we evaluate the overhead of the system, including the detection delay and utilization of CPU, which is not excessive. Our anomaly detection approach is lightweight and effective.

• 대한조선학회논문집
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• 제56권6호
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• pp.541-549
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• 2019

In the present study, we investigated planing forces of supercavitated bodies by using the supercavitation shape produced by the disk type cavitator. The cavity shapes are observed to find the immersion draft and planing angle when the stern of the supercavitated body is partially immersed in the water. To make the planing the angle-of-attack (AOA) of the supercavitated body is varied statically against the main flow and the planing tests are carried out for different body shapes that are changed systematically. The drag, lift and pitch moment acting on the body are measured to understand the relation between the planing force and the immersion draft of the supercavitated body. It is found that the planing force increased in general linearly with the immersion draft ratio and the planing angle is certainly not proportional to the immersion draft ratio.

• 한국군사과학기술학회지
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• 제23권4호
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• pp.363-370
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• 2020

In this study, pitching stability derivatives of the conical shell configuration is predicted using commercial CFD code. Unsteady flow analysis with forced harmonic motion of the model is performed using overset mesh. The test is conducted about Basic finner missile configuration. The static and dynamic stability derivatives are good agreement with available experimental data. As the same way, a conical shell is analyzed in Mach number 1.6 and various reduced frequency. The static and dynamic derivatives are obtained from the time-pitching moment coefficient histories in each of four cases of mean angle of attack. The variation of reduced frequency is not affected static and dynamic derivatives. Increasing the mean angle of attack, static derivatives are increased slowly. Comparison of the Cm curves at the steady and unsteady state results shows that the Cm curve including the damping effect is lower than otherwise case, approximately 9-18 %.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.780-787
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• 2018

This article presents a security module based on a field programmable gate array (FPGA) to mitigate man-in-the-middle cyber attacks. Nowadays, the FPGA is considered to be the state of the art in nuclear power plants I&C systems due to its flexibility, reconfigurability, and maintainability of the FPGA technology; it also provides acceptable solutions for embedded computing applications that require cybersecurity. The proposed FPGA-based security module is developed to mitigate information-gathering attacks, which can be made by gaining physical access to the network, e.g., a man-in-the-middle attack, using a cryptographic process to ensure data confidentiality and integrity and prevent injecting malware or malicious data into the critical digital assets of a nuclear power plant data communication system. A model-based system engineering approach is applied. System requirements analysis and enhanced function flow block diagrams are created and simulated using CORE9 to compare the performance of the current and developed systems. Hardware description language code for encryption and serial communication is developed using Vivado Design Suite 2017.2 as a programming tool to run the system synthesis and implementation for performance simulation and design verification. Simple windows are developed using Java for physical testing and communication between a personal computer and the FPGA.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.383-390
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• 2008

Flow pattern of cavitation around a plano-convex foil, whose shape is similar to the inducer impeller of the turbo-pumps in the liquid fuel rocket engine, was observed by using a cryogenic cavitation tunnel of blowdown type for visualization. Working fluids were liquid nitrogen and hot water. The parameter range to be varied was between 20 and 60mm for channel width, 20 and 60mm for foil chord, -1.8 and 13.2 for cavitation number, 3.7 and 19.5m/sec for averaged inlet velocity, $8.5{\times}10^4$ and $1.5{\times}10^6$ for Reynolds number, -8 and $8^{\circ}$ for angle of attack, respectively. Especially at positive angle of attack, namely, convex surface being downstream, the whole cavity or a part of the cavity on the foil surface departs periodically. Periodic cavitation occurs only in case of smaller cavitation size than twice foil chord. Cavitation thickness and length in 20mm wide channel are larger than those in 60mm due to the wall confinement effect. Therefore, periodic cavitation in 60mm wide channel easily occurs than that in 20mm. These results suggest that the periodic cavitation is controlled by not only the hydrodynamic effect of vortex shedding but also the channel wall confinement effect.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권6호
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• pp.1689-1705
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• 2023

To deal with the potential XSS vulnerabilities in the source code of the power communication network, an XSS vulnerability detection method combining the static analysis method with the dynamic testing method is proposed. The static analysis method aims to analyze the structure and content of the source code. We construct a set of feature expressions to match malignant content and set a "variable conversion" method to analyze the data flow of the code that implements interactive functions. The static analysis method explores the vulnerabilities existing in the source code structure and code content. Dynamic testing aims to simulate network attacks to reflect whether there are vulnerabilities in web pages. We construct many attack vectors and implemented the test in the Selenium tool. Due to the combination of the two analysis methods, XSS vulnerability discovery research could be conducted from two aspects: "white-box testing" and "black-box testing". Tests show that this method can effectively detect XSS vulnerabilities in the source code of the power communication network.

• Wind and Structures
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• 제35권4호
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• pp.243-253
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• 2022

The conformal mapping method (CMM) has been broadly exploited in the study of fluid flows over airfoils and other research areas, yet it's hard to find relevant research in bridge engineering. This paper explores the feasibility of CMM in streamlined box girder bridges. Firstly, the mapping function transforming a unit circle to the streamlined box girder was solved by CMM. Subsequently, the potential flow solution of aerostatic pressure on the streamlined box girder was obtained and was compared with numerical simulation results. Finally, the aerostatic pressure attained by CMM was utilized to estimate the aerostatic coefficient and flutter performance of the streamlined box girder. The results indicate that the solution of the aerostatic pressure by CMM on the windward side is satisfactory within a small angle of attack. Considering the windward aerostatic pressure and coefficient of correction, CMM can be employed to estimate the rate of change of the lift and moment coefficients with angle of attack and the influence of the geometric shape of the streamlined box girder on flutter performance.

• Wind and Structures
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• 제38권2호
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• pp.147-160
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• 2024

The aerodynamic force is a significant component that influences the stability and safety of structures. It has unstable properties and depends on computer precision, making its long-term prediction challenging. Accurately estimating the aerodynamic traits of structures is critical for structural design and vibration control. This paper establishes an unsteady aerodynamic time series prediction model using Long Short-Term Memory (LSTM) network. The unsteady aerodynamic force under varied Reynolds number and angles of attack is predicted by the LSTM model. The input of the model is the aerodynamic coefficients of the 1 to n sample points and output is the aerodynamic coefficients of the n+1 sample point. The model is predicted by interpolation and extrapolation utilizing Unsteady Reynolds-average Navier-Stokes (URANS) simulation data of flow around a circular cylinder, square cylinder and airfoil. The results illustrate that the trajectories of the LSTM prediction results and URANS outcomes are largely consistent with time. The mean relative error between the forecast results and the original results is less than 6%. Therefore, our technique has a prospective application in unsteady aerodynamic force prediction of structures and can give technical assistance for engineering applications.