• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.4
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• pp.693-704
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• 2020

As a company's network structure is getting bigger and the number of security system is increasing, it is not easy to quickly detect abnormal traffic from huge amounts of security system events. In this paper, We propose traffic visualization analysis system(FDANT-PCSV) that can detect and analyze security events of information security systems such as firewalls in real time. FDANT-PCSV consists of Parallel Coordinates visualization using five factors(source IP, destination IP, destination port, packet length, processing status) and Sankey visualization using four factors(source IP, destination IP, number of events, data size) among security events. In addition, the use of big data-based SIEM enables real-time detection of network attacks and network failure traffic from the internet and intranet. FDANT-PCSV enables cyber security officers and network administrators to quickly and easily detect network abnormal traffic and respond quickly to network threats.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1086-1095
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• 2013

The main issue of parallel three-phase boost converters is reduction of the low- and high frequency circulating currents. Most present technologies concentrate on low frequency circulating current because the circulating current controller cannot mitigate the high frequency circulating current. In this paper, analytical approach of three-phase coupled inductor applied to parallel system becomes an important objective to effectively reduce the low- and high frequency circulating currents. The characteristics of three-phase coupled inductor based on a structure and voltage equations are mathematically derived. The modified voltage equations are then applied to parallel three-phase boost converters to develop averaged models in stationary coordinates and rotating coordinates. Based on the averaged modeling approach, design of the circulating current controller is presented. Simulation and experimental results demonstrate the effectiveness of the analysis and modeling for the parallel three-phase boost converters using three-phase coupled inductor.

• Communications for Statistical Applications and Methods
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• v.8 no.3
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• pp.643-650
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• 2001

Some classical plots like scatterplot matrices and parallel coordinates are valuable tools for data visualization. These tools are extensively used in the modern data mining softwares to explore the inherent data structure, and hence to visually classify or cluster the database into appropriate groups. However, the interpretation of these plots are very sensitive to the arrangement of variables. In this work, we introduce two methods to arrange the variables for data visualization. First method is based on the work of Wegman (1999), and this is to arrange the variables using minimum distance among all the pairwise permutation of the variables. Second method is using the idea of principal components. We Investigate the effectiveness of these methods with parallel coordinates using real data sets, and show that each of the two proposed methods has its own strength from different aspects respectively.

• Spatial Information Research
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• v.17 no.3
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• pp.371-379
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• 2009

Recently, GPU (Graphics Processing Unit) has been improved rapidly on the need of speed for gaming. As a result, GPU contains multiple ALU (Arithmetic Logic Unit) for parallel processing of a lot of graphics data, such as transform, ray tracing, etc. Therefore, this paper proposed a technique for parallel processing of spatial data using GPU. Spatial data consists of multiple coordinates, and each coordinate contains value of x and y axis. To display spatial data graphics operations have to be processed to large amount of coordinates. Because the graphics operation is identical and coordinates are multiple data, SIMD (Single Instruction Multiple Data) parallel processing of GPU can be used for processing of spatial data to improve performance. This paper implemented SIMD parallel processing of spatial data using two kinds of SDK (Software Development Kit). CUDA and ATI Stream are used for NVIDIA and ATI GPU respectively. Experiments that measure time of calculation for graphics operations are carried out to observe enhancement of performance. Experimental result is reported that proposed method can enhance performance up to 1,162% for graphics operations. The proposed method that uses parallel processing with GPU for spatial data can be generally used to enhance performance for applications which deal with large amount of spatial data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1067-1070
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• 1995

In this paper, we have treated the modeling and development of three degree of freedom parallel manipulator for micromotion based on the Stewart platform type parallel structure. the kinematic modeling was derived from the relation between base coordinate and platform anr the dynamic modeling was from the method of Kinematic Influence Coefficients(KIC) and transferring of the generalized coordinates. Using this method, we presented the method to choose the actuator and joint by investigating the actuating forces needed when the manipulator moves along the given trajectory. In the end, the prototype manipulator was developmented and evaluated.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.55-56
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• 2017

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.507-515
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• 2017

Flexible multibody simulations are widely used in the industry to design mechanical systems. In flexible multibody dynamics, deformation coordinates are described either relatively in the body reference frame that is floating in the space or in the inertial reference frame. Moreover, these deformation coordinates are generated based on the discretization of the body according to the finite element approach. Therefore, the formulation of the flexible multibody system always deals with a huge number of degrees of freedom and the numerical solution methods require a substantial amount of computational time. Parallel computational methods are a solution for efficient computation. However, most of the parallel computational methods are focused on the efficient solution of large-sized linear equations. For multibody analysis, we need to develop an efficient formulation that could be suitable for parallel computation. In this paper, we developed a subsystem synthesis method for a flexible multibody system and proposed efficient parallel computational schemes based on the OpenMP API in order to achieve efficient computation. Simulations of a rotating blade system, which consists of three identical blades, were carried out with two different parallel computational schemes. Actual CPU times were measured to investigate the efficiency of the proposed parallel schemes.

• Journal of Mechanical Science and Technology
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• v.16 no.8
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• pp.1053-1063
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• 2002

This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.130-132
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• 2005

인터넷상의 수많은 트래픽 정보 중에서 악성 트래픽 정보를 빠르게 감지하는 것은 그 정보의 방대함 때문에 쉽지 않다. 공격시각회(Attack Visualization) 기법은 이런 수많은 정보 중에서 악성 트래픽 정보를 좀 더 쉽게 인지하게 함으로써 새로운 공격에 대해서 빠른 대응과 피해 최소화를 하는데 활용할 수 있다. 본 연구에서는 평행좌표계(Parallel Coordinates)를 이용해 공격시각화를 하여, 분산 서비스 거부 공격, 웜, 스캐닝 공격 등 인터넷상에 알려진 혹은 알려지지 않은 새로운 공격들에 대해 빠른 대응을 하기위한 기술 연구를 하였으며, 각 공격들의 특정 시각화 패턴을 감지하고 이를 알려주는 이상탐지(anomaly detection) 시각화 시스템 PCAV를 구현하였다. PCAV 시스템을 통해 네트워크 관리자는 실시간으로 트래픽 정보와 공격들의 시각화 정보를 원격에서도 모니터링하고 이를 통해 즉시 대응하는 것이 가능하다. 또한, 이전에 발생한 공격들의 시각화 정보를 확인하고 이를 분석하는 것과, 알려지지 않은 공격이 발생했을지라도 그 공격의 시각적 패턴이 나타났을 때 즉각 공격 서명(Signature)으로 활용 하는 것이 가능하다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.44-44
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• 2000

Firstly, kinematic model of various type of wheels which includesskidding and skidding friction are presented. Tend, the transfer method of generalized coordinates which is useful to model the parallel mechanisms, can be applied to mobile robot by including such friction terms. Particularly, by appling the modeling method to mobile robot consisting of two conventional wheels and one caster wheel, forword/reverse kinematic modeling could be obtained without using pseudoinverse solutions.