• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.806-811
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• 2005

The robot to search and rescue is used in narrow space where human cannot approach. In case of this robot, it can overcome obstacles such as wrecks or stairs etc. Also, this robot can do various locomotion for each object. In this reason, an articulated robot has advantages comparing with one module robot. However, the existing articulated robot has limits to overcome vertical passages. For expanding contacted territory of robot, a novel mechanism is demanded. In this paper, the novel mechanism of articulated mobile robot is designed for moving level ground and vertical passages. This paper proposes to change wheel alignment. The robot needs two important motions for passing vertical passages like pipe. One is a motion to press wheels at wall for not falling into gravity direction. The other is a motion that wheels contact a vertical direction of wall's tangential direction for reducing loss of force. The mechanism of the robot focused that two motions can be acted to use just one motor. Length of each link of robot is optimized that wheels contact a vertical direction of wall's tangential direction through kinematic modeling of each link. The force of pressing wall of robot is calculated through dynamic modeling. This robot composes four modules. This mechanism is confirmed by dynamic simulation using ADAMS program. The articulated mobile robot is elaborated based on the results of kinematic modeling and dynamic simulation.

• Journal of IKEEE
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• v.26 no.3
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• pp.380-388
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• 2022

The traditional malware detection technologies collect known malicious programs and analyze their characteristics. Then such a detection technology makes a blacklist based on the analyzed malicious characteristics and checks programs in the user's system based on the blacklist to determine whether each program is malware. However, such an approach can detect known malicious programs, but responding to unknown or variant malware is challenging. In addition, since such detection technologies generally monitor all programs in the system in real-time, there is a disadvantage that they can degrade the system performance. In order to solve such problems, various methods have been proposed to analyze major behaviors of malicious programs and to respond to them. The main characteristic of ransomware is to access and encrypt the user's file. So, a new approach is to produce the whitelist of programs installed in the user's system and allow the only programs listed on the whitelist to access the user's files. However, although it applies such an approach, attackers can still perform malicious behavior by performing a DLL(Dynamic-Link Library) injection attack on a regular program registered on the whitelist. This paper proposes a method to respond effectively to attacks using DLL injection.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.53-60
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• 2011

The available power generated from the FC power plant may not be sufficient to meet sustained load demand, peak demand or transient events. An supercapacitor bank(SCB) can supply a large burst of power, but it cannot store a significant amount of energy. The combined use of FC and SCB has the potential for the better energy efficiency, reducing the cost of FC technology and improved dynamic response. In this paper, A single PEMFC and PEMFC operated in parallel with a SC bank are presented, A new dynamic model of PEMFC system, the converter and controller has been developed for stand-alone applications. The simulation results are presented using Matlab/Simulink, and SimPowerSystems environments. It is confirmed that the results show a good performance and stable DC-link voltage for proposed dynamic and mathematical models developed for the combined FC/SCB.

• Korean System Dynamics Review
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• v.1 no.1
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• pp.159-183
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• 2000

How to protect the environment without sacrificing the human environment and economy at the level of region is on of the most difficult issues of recent times. The dynamic Interactions between economic activities and environmental pollution control activities determine whether social welfare is increased of decreased by such activities and provides a basis for saying whether they help or hurt the economy. Bureaucratic Approach of Local government has failed, and an Impetus has arisen to develop new tools of analysis, useful for finding policy leverages focused on sustainability. This paper focus on understanding dynamic relationships between regional economic system and environmental system, and presenting possible framework for finding policy leverages in dynamic interaction behaviors. The case, selected in this study, is Nacdong river regions case, which is related many meaningful issues about sustainable development： two big metropolitan government and dwellers have different opinion with regard to construction of large scale Industrial pack, drinking water supply, and environment model consisting of three sectors： regional economy sector, river pollution and drinking water sector, environmental protection and investment policy sector Finally, this paper deal with how to link policy leverage to causal loop structure for the sustainable development of two regions.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2430-2434
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• 2003

This paper provides a new approach to analyze the stability of TCP Vegas, which is a kind of feedback-based congestion control algorithm. Whereas the conventional approaches use the approximately linearized model of the TCP Vegas along equilibrium points, this approach uses the exactly characterized dynamic model to get a new stability criterion via a piecewise and delay-dependent Lyapunov-Krasovskii function. Especially, the resulting stability criterion is formulated in terms of linear matrix inequalities (LMIs). Using the new criterion, this paper shows that the current TCP Vegas algorithm is stable in the sufficiently wide region of network delay and link capacity.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.123-124
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• 2017

Cascaded NPC/H-Bridge(CNHB) 컨버터는 전압 레벨 증가의 용이성 및 고효율 양방향 토폴로지로써 대전력 및 고전압 전력변환장치에 널리 사용되고 있다. 하지만 과도상태 및 정상상태에서의 단상으로 구성된 각 DC-link의 전압변동은 DC-link의 커패시턴스 증가 및 출력 전력의 품질을 저하시킨다. 이에 본 논문은 CNHB 컨버터의 정상상태 특성과 동특성 개선을 위하여 PI제어와 모델예측제어를 혼합한 제어기법을 제안한다. 제안한 기법의 타당성은 PSIM 9.1.4 시뮬레이션을 이용하여 검증한다.

• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.162-170
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• 2003

In this paper, we propose a robust controller for trajectory control of n-link robot manipulators using feature based on visual feedback. In order to reduce tracking error of the robot manipulator due to parametric uncertainties, integral action is included in the dynamic control part of the inner control loop. The desired trajectory for tracking is generated from feature extraction by the camera mounted on the end effector. The stability of the robust state feedback control system is shown by the Lyapunov method. Simulation and experimental results on a 5-link robot manipulator with two degree of freedom show that the proposed method has good tracking performance.

• Journal of the Korean Society for Railway
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• v.5 no.1
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• pp.18-25
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• 2002

This paper is to study a comparison of ride stabilities for the guideway vehicle between its three primary steering types; the front-rear wheel steering type, tile independent wheel steering and the front wheel steering. A numerical model were built to investigate various factors to have an influence on the vehicular stability. It was shown that dynamic stabilities of the three types were dependent on the steering gain ratio of front wheel steering to rear. The front-rear wheel steering type was more stable for the value of positive steering gains and the shorter distance between front axle and guide link showed better stabilities. On the contrary, the independent wheel steering was more stable for the value of negative gains and the longer distance between front axle and guide link showed better stabilities. Ride characteristics of he front wheel steering seemed to be found midway. Ride behaviors due to time delay from front steering to rear were very different from steering type to type.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.123-129
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• 2001

Recent requirements for the fast and accurate motion in industrial robot manipulators need more advanced control tech-niques. To satisfy the requirements, importance of force control is being continuously increased and the expensive force sensor is usually installed to obtain the contact force information in practice. This information is indispensable for the force control of maintaining the desired contact force. However, the sensor cost is too high to be used in industrial applications. In this paper, it is proposed to estimated the contact force occurring between the end-effector of 2 DOF robots and environ-ment. The contact force estimation system is developed based on the static and dynamic models of 2 DOF robot manipula-tors. where the contact force is described with respect to the link torque. The Extended Kalman Filter is designed and its performance is verified in simulations.

• Journal of Power System Engineering
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• v.5 no.2
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• pp.79-86
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• 2001

A method is presented for generating the path which significantly reduces residual vibration of the redundant, flexible robot manipulator in the presence of obstacles. The desired path is optimally designed so that the system completes the required move with minimum residual vibration, avoiding obstacles. The dynamic model and optimal path are effectively formulated and computed by using special moving coordinate, called VLCS, to represent the link flexibility. The path to be designed is developed by a combined Fourier series and polynomial function to satisfy both the convergence and boundary condition matching problems. The concept of correlation coefficients is used to select the minimum number of design variables. A planar three-link manipualtor is used to evaluate this method. Results show that residual vibration can be drastically reduced by selecting an appropriate path, in the presence of obstacles.