• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.12
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• pp.1433-1441
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• 2009

In multibody dynamic analysis, one of the most important problems is to reduce computation times for real-time simulation. This paper presents the derivation procedure of equations of motion of a 6${\times}$6 autonomous vehicle in terms of chassis local coordinates which do not require coordinates transformation matrix to enhance efficiency for real-time dynamic analysis. Also, equations of motion are derived using the VT(velocity transformation) technique and symbolic computation method coded by MATLAB. The Jacobian matrix of the equations of motion of a system is derived from symbolic operations to apply the implicit integration method. The analysis results were compared with ADAMS results to verify the accuracy and approve the feasibility of real time analysis.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.389-390
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• 2009

컴퓨터에서 생성된 시뮬레이션의 결과는 컴퓨터 그래픽스 기술을 이용한 일련의 가시화 과정을 거쳐서 인간이 해석하기 쉬운 형태로 변형되게 된다. 최근에는 고성능 컴퓨터(HPC: High Performance Computer)의 발달로 인해 데이터의 크기가 점점 더 증가하는 추세에 있으며, 이런 복잡한 데이터를 해석하는 데는 클러스터 시스템을 이용한 고해상도의 디스플레이 장치가 필요하다. 하지만 이런 디스플레이 장치에서 사용자 인터페이스를 제공하는 방법은 VR(Virtual Reality, 가상현실) 환경을 활용하는 것이 거의 유일한 해결책이다. 하지만 현재 VR 환경에서 시뮬레이션 데이터 해석에 필요한 적절한 사용자 인터페이스를 제공하는 툴은 존재하지 않는다. 이에, 본 논문에서는 시뮬레이터 데이터, 특히 로터 동역학 분야의 시뮬레이션 데이터를 VR 환경에서 가시화하는 GLOVE 프레임워크의 통합 인터페이스를 소개한다. 이 인터페이스는 VR 환경에서 시뮬레이션 데이터를 실시간으로 상호작용을 통해 분석하는 데 필요한 기반 환경을 제공한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1069-1075
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• 2013

An effective method is necessary for the real-time analysis of an unmanned military robot. To achieve highly efficient simulations, a subsystem synthesis method has been developed. The subsystem synthesis method separately generates equations of motion for the base body and for the subsystem. The equations of motion are expressed by DAE, which consist of differential equations and algebraic equations. To increase the accuracy and efficiency of solutions, DAE solvers such as the Direct, CS (Constraint Stabilization), and GCP (Generalized Coordinate Partitioning) method are employed. In this study, the subsystem synthesis method is applied for effective multi-body dynamics analysis of an unmanned military robot, and a comparative study of three different DAE solvers is carried out.

• Journal of Aerospace System Engineering
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• v.18 no.4
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• pp.18-26
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• 2024

This paper describes the results of a study on Generic Quad Tilt Rotor UAM aircraft, focusing on nonlinear mathematical modeling and the development of real-time simulation software. In this research, we designed a configuration for a Generic Quad Tilt Rotor eVTOL UAM aircraft based on NASA's UAM mission requirements. We modeled the aerodynamics using a database, the prop-rotor dynamics with a thrust database, and included a ground reaction and atmospheric model in the flight model. We defined the control concept for various modes(helicopter mode, transition mode, and airplane mode), derived tilt angle corridors, and formulated flight control requirements. The resultant real-time flight simulation software not only performs trim analysis for Tilt Rotor UAM aircraft but also predicts handling qualities, optimizes tilt angle scheduling based on dynamic characteristics, designs and validates flight control laws for helicopter, transition, and airplane modes, and facilitates flight training through simulator integration.

• Journal of Korea Water Resources Association
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• v.33 no.3
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• pp.331-340
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• 2000

This study aims to develop a methodology of real time forecasting of mundation risk based on DAMBRK model and Kalman filter. The model is based on implicit, nonlinear finite difference approximatIons of the one-dimensional dynamic wave equations. The stochastic estimator uses on extended Kalman filter to provide optimal updating estimates. These are accomplished by combining the predictions of the determurustic model with real time observauons modified by the Kalman filter gain ractor. Inundation risks are also estimated by applying Monte Carlo simulation to consider the variability in cross section geometry and Manning's roughness coefficient. The model calibrated by applying to the floods ot South Han River on September, 1990 and August, 1995. The Kalman tilter model indicates that significant improvement compared to deteriministic analysis in flood routing predictions in the river. Overtopping risk of levee is also presented by comparing levee height with simulated flood level. level.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.321-322
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• 2022

In this study, the marine environment is measured and analyzed in real time through the X-band radar installed on the rooftop of the Sokcho Beach administrative Welfare Center and Ulleungdo. Afterwards, the goal is to transmit the analysis results to the client PC. Using electronic maps and electronic navigational charts, the measurement results are overlaid on GIS (spatial information system), real-time data are shared through a website, and information is displayed through a web server. Currently, CCTV information and marine environment information are displayed on the website, but various application studies such as the use of Open AP I will be conducted in the future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.525-530
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• 2016

In this paper, we proposed an image shaking index to evaluate the remote controllability of vision based unmanned vehicles. To analyze the usefulness of the proposed image-shaking index, we perform subjective tests using a virtual unmanned vehicle driving simulator. The developed driving simulator consists of a real-time multibody dynamic software of the unmanned vehicle, a motion simulator, and a driver console. We perform dynamic simulations to obtain the motion of the unmanned vehicle running on the various road surfaces such as ISO roughness level A~E roads. The motion of the vehicle body is reflected in the motion simulator. Then, to enable remote control operation, we offer to operators the image data that was measured using the camera sensor on the simulator. We verify the usefulness of the proposed image-shaking index compared with subjective index provided by operators.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.4
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• pp.311-320
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• 2021

A study is performed for the real time fault diagnosis during operation and health estimation relating to performance deterioration in a turbojet engine used for an unmanned air vehicle. For this study the real time dynamic model is derived from the transient thermodynamic gas path analysis. For real fault conditions which are manipulated for the simulation, the detection techniques are applied such as Kalman filter and probabilistic decision-making approach based on statistical hypothesis test. Thereby the effectiveness is verified by showing good fault detection and isolation performances. For the health estimation with measurement parameters, it shows using an assumed performance degradation that the method by adaptive Kalman filter is feasible in practice for a condition based diagnosis and maintenance.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.31.2-31.2
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• 2010

편대비행 위성이 공동의 임무를 수행하기 위해서는 편대를 이루는 위성의 각기 다른 초기 오차와 다양한 외란 환경에서도 자세 동기화를 이룰 수 있는 기법이 필요하다. 이 연구에서는 편대비행위성의 자세 동기화를 위하여 비선형 시스템에 대한 준최적 제어기법인 SDRE(State-Dependent Riccati Equation)에 기반한 추적 제어기가 사용되었다. 반작용 휠이 포함된 위성의 자세 동역학이 SDRE 추적 제어기를 구성하는데 이용된다. 이를 Leader/Follower 편대비행 시스템에 적용하며, 기준 자세를 추적하는 Leader 위성의 자세를 Follower 위성이 추적하여 자세 동기화를 이룰 수 있다. MATLAB과 SIMULINK를 이용한 수치해석적 시뮬레이션으로 추적 제어기의 성능을 검증하였으며, 이에 대한 실시간 HIL(Hardware-In-the-Loop) 시뮬레이션이 수행되었다. 무중력 환경을 모사하는 에어베어링시스템과 세 개의 반작용 휠을 장착한 자세제어 HILS(Hardware-In-the-Loop Simulator)는 PC104 타입의 임베디드 컴퓨터에서 SIMULINK의 xPC Target을 이용한 실시간 시뮬레이션 환경을 제공하며, 이에 적용되는 SDRE 추적 제어기는 이산화되어 설계되었다. 또한 SDRE 추적 제어기에 대한 안정성을 보장하는 영역이 추정되어 위 추적 제어기가 위성 편대비행에 적합한 자세 동기화 기법임을 보였다.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.8-15
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• 2004

With all the recent progresses in computer hardware and software technology, the animation of fluids in real-time is still among the most challenging issues of computer graphics. The fluid animation is carried out in two steps - the physical simulation of fluids immediately followed by the visual rendering. The physical simulation is usually accomplished by numerical methods utilizing the particle dynamics equations as well as the fluid mechanics based on the Navier-Stokes equations. Particle dynamics method is usually fast in calculation, but the resulting fluid motion is conditionally unrealistic. The methods using Navier-Stokes equation, on the contrary, yield lifelike fluid motion when properly conditioned, yet the complexity of calculation restrains this method from being used in real-time applications. This article presents a rapid fluid animation method by using the continuum-based fluid mechanics and the enhanced particle dynamics equations. For real-time rendering, pre-integrated volume rendering technique was employed. The proposed method can create realistic fluid effects that can interact with the viewer in action, to be used in computer games, performances, installation arts, virtual reality and many similar multimedia applications.