• Title/Summary/Keyword: Initial Trajectory

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The consideration on changes of ship's trajectory in case-by-case initial response to cognitive situation by SHS (SHS에 의한 인지상황 초기대응 사례별 선박 궤적 변화 고찰)

  • Yoon, Cheong-Guem;Kim, Deok-Bong
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2016.05a
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    • pp.199-201
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    • 2016
  • The performance of navigational equipments is advanced, but the importance of the practical capability of bridge device by ship's officer, ie the ability of risk prediction and the obligation of avoidance for reducing sea accident, has been constantly augmenting. This abilities and obligation may be represented in the cognitive competence of navigational officer. Different levels of ship's bridge team was carried out rescue maneuvering by ship handling simulator and then it analyzed the resulting of initial response in cognitive progress by case based on trajectory. Further, the data will be used as training and evaluation model of cognitive situation.

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ON A TIME-CONSISTENT SOLUTION OF A COOPERATIVE DIFFERENTIAL TIME-OPTIMAL PURSUIT GAME

  • Kwon, O-Hun;Svetlana, Tarashinina
    • Journal of the Korean Mathematical Society
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    • v.39 no.5
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    • pp.745-764
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    • 2002
  • In this paper we Study a time-optimal model of pursuit in which the players move on a plane with bounded velocities. This game is supposed to be a nonzero-sum group pursuit game. The main point of the work is to construct and compare cooperative and non-cooperative solutions in the game and make a conclusion about cooperation possibility in differential pursuit games. We consider all possible cooperations of the players in the game. For that purpose for every game $\Gamma(x_0,y_0,z_0)$ we construct the corresponding game in characteristic function form $\Gamma_v(x_0,y_0,z_0)$. We show that in this game there exists the nonempty core for any initial positions of the players. The core can take four various forms depending on initial positions of the players. We study how the core changes when the game is proceeding. For the original agreement (an imputation from the original core) to remain in force at each current instant t it is necessary for the core to be time-consistent. Nonemptiness of the core in any current subgame constructing along a cooperative trajectory and its time-consistency are shown. Finally, we discuss advantages and disadvantages of choosing this or that imputation from the core.

The Influence of Collision Energy on the Reaction H+HS→H2+S

  • Liu, Yanlei;Zhai, Hongsheng;Zhu, Zunlue;Liu, Yufang
    • Bulletin of the Korean Chemical Society
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    • v.34 no.11
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    • pp.3350-3356
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    • 2013
  • Quasi-classical trajectory calculations have been carried out for the reaction H+HS by using the newest triplet 3A" potential energy surface (PES). The effects of the collision energy and reagent initial rotational excitation are studied. The cross sections and thermal rate constants for the title reaction are calculated. The results indicate that the integral cross sections (ICSs) are sensitive to the collision energy and almost independent to the initial rotational states. The ro-vibrational distributions for the product $H_2$ at different collision energies are presented. The investigations on the vector correlations are also performed. It is found that the collision energies play a postive role on the forward scatter of the product molecules. There is a negative influence on both the alignment and orientation of the product angular momentum for low collision energy at low energy region. Whereas the influence of collision energy is not obvious at high energy region.

PWSCC Crack Growth Analysis Using Numerical Method in the Inner Surface Repair Weld of A Nozzle (노즐 이종금속용접부의 내면 보수용접부에서 수치해석법을 이용한 PWSCC 균열성장해석)

  • Kim, Sang-Chul;Kim, Mann-Won
    • Journal of Welding and Joining
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    • v.29 no.2
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    • pp.64-71
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    • 2011
  • In this paper, crack propagation analyses in the inner diameter (ID) repair weld of the dissimilar metal weldment of a nozzle were performed using a finite element alternating method (FEAM). To calculate the theoretical solution for the crack tip stress intensity factor, a weak type singular integral equation consisted of crack surface traction and dislocation density function was constructed and solved in conjunction with the FEAM. A two-dimensional axisymmetric finite element nozzle model was prepared and ID repair welding was simulated. An initial crack, 10% depth of weld thickness, was assumed and crack propagation trajectory from the initial crack to the 75% depth of thickness was calculated using the FEAM. Crack growth versus time curve was also calculated and compared with the curves obtained from ASME code method. With the method constructed in this paper, crack propagation trajectory and crack growth time were calculated automatically and effectively.

Unguided Rocket Trajectory Analysis under Rotor Wake and External Wind (로터 후류와 외풍에 따른 무유도 로켓 궤적 변화 해석)

  • Kim, Hyeongseok;Chae, Sanghyun;Yee, Kwanjung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.1
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    • pp.41-51
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    • 2018
  • Downwash from helicopter rotor blades and external winds from various maneuvering make an unguided rocket change its trajectory and range. For the prediction of the trajectory and range, it is essential to consider the downwash effect. In this study, an algorithm was developed to calculate 6-Degree-Of-Freedom(6 DOF) forces and moments exerting on the rocket, and total flight trajectory of a 2.75-inch unguided rocket in a helicopter downwash flow field. Using Actuator Disk Model(ADM) analysis result, the algorithm could analyze the entire trajectory in various initial launch condition such as launch angle, launch velocity, and external wind. The algorithm that considered the interference between a fuselage and external winds could predict the trajectory change more precisely than inflow model analysis. Using the developed algorithm, the attitude and trajectory change mechanism by the downwash effect were investigated analyzing the effective angle of attack change and characteristics of pitching stability of the unguided rocket. Also, the trajectory and range changes were analyzed by considering the downwash effect with external winds. As a result, it was concluded that the key factors of the rocket range change were downwash area and magnitude which effect on the rocket, and the secondary factors were the dynamic pressure of the rocket and the interference between a fuselage and external winds. In tailwind case which was much influential on the range characteristics than other wind cases, the range of the rocket rose as increasing the tailwind velocity. However, there was a limit that the range of the rocket did not increase more than the specific tailwind velocity.

A Study on the Changing Trajectory of Game Use and the Current and Lag Effect from Self-Control during Early Adolescences (초기 청소년의 게임사용 변화궤적과 자기통제력의 동시효과 및 지연효과 연구)

  • Heo, Gyun
    • The Journal of Korean Association of Computer Education
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    • v.15 no.3
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    • pp.71-80
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    • 2012
  • The purpose of this study is to find out the changing trajectory of online game use as the development of early adolescences. It is also to explore whether the self-control has a current and a lag effect on the game use while development of students. We found these results: (a) There is a statically significant individual variability in initial levels and rates of change in online game use over time. The change of trajectory is declined. (b) Boys also have higher rate of the change in using game than girls over time. (c) Both initial state and changing rate of online game use affects negatively the academic achievement. (d) Current effect always supports, but lag effect does not support except the period from last elementary school grade to middle school grade as explanations for the developmental relation between self-control and online game use in young adolescents.

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3D printing of multiple container models and their trajectory tests in calm water

  • Li, Yi;Yu, Hanqi;Smith, Damon;Khonsari, M.M.;Thiel, Ryan;Morrissey, George;Yu, Xiaochuan
    • Ocean Systems Engineering
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    • v.12 no.2
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    • pp.225-245
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    • 2022
  • More and more shipping containers are falling into the sea due to bad weather. Containers lost at sea negatively affect the shipping line, the trader and the consumer, and the environment. The question of locating and recovering dropped containers is a challenging engineering problem. Model-testing of small-scaled container models is proposed as an efficient way to investigate their falling trajectories to salvage them. In this study, we first build a standard 20-ft container model in SOLIDWORKS. Then, a three-dimensional (3D) geometric model in the STL (Standard Tessellation Language) format is exported to a Stratasys F170 Fused Deposition Modeling (FDM) printer. In total, six models were made of acrylonitrile styrene acrylate (ASA) and printed for the purpose of testing. They represent three different loading conditions with different densities and center of gravity (COG). Two samples for each condition were tested. The physical models were dropped into the towing tank of University of New Orleans (UNO). From the experimental tests, it is found that the impact of the initial position after sinking can cause a certain initial rolling velocity, which may have a great impact on the lateral displacement, and subsequently affect the final landing position. This series of model tests not only provide experimental data for the study of the trajectory of box-shape objects but also provide a valuable reference for maritime salvage operations and for the pipeline layout design.

Stability Research on Aerodynamic Configuration Design and Trajectory Analysis for Low Altitude Subsonic Unmanned Air Vehicle

  • Rafique, Amer Farhan;He, LinShu
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.690-699
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    • 2008
  • In this paper a conventional approach for design and analysis of subsonic air vehicle is used. First of all subsonic aerodynamic coefficients are calculated using Computational Fluid Dynamics(CFD) tools and then wind-tunnel model was developed that integrates vehicle components including control surfaces and initial data is validated as well as refined to enhance aerodynamic efficiency of control surfaces. Experimental data and limited computational fluid dynamics solutions were obtained over a Mach number range of 0.5 to 0.8. The experimental data show the component build-up effects and the aerodynamic characteristics of the fully integrated configurations, including control surface effectiveness. The aerodynamic performance of the fully integrated configurations is comparable to previously tested subsonic vehicle models. Mathematical model of the dynamic equations in 6-Degree of Freedom(DOF) is then simulated using MATLAB/SIMULINK to simulate trajectory of vehicle. Effect of altitude on range, Mach no and stability is also shown. The approach presented here is suitable enough for preliminary conceptual design. The trajectory evaluation method devised accurately predicted the performance for the air vehicle studied. Formulas for the aerodynamic coefficients for this model are constructed to include the effects of several different aspects contributing to the aerodynamic performance of the vehicle. Characteristic parameter values of the model are compared with those found in a different set of similar air vehicle simulations. We execute a set of example problems which solve the dynamic equations to find the aircraft trajectory given specified control inputs.

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A Study on Position Control of 2-Mass Resonant System Using Iterative Learning Control (반복 학습 제어를 이용한 2관성 공진계의 위치 제어에 관한 연구)

  • Lee, Hak-Sung;Moon, Seung-Bin
    • Journal of the Korean Institute of Intelligent Systems
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    • v.14 no.6
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    • pp.693-698
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    • 2004
  • In this paper, an iterative learning control method is applied to suppress a vibration of a 2-mass system which has a flexible coupling between a load and a motor. More specifically, conditions for the load speed without vibration are derived based on the steady-state condition. And the desired motor position trajectory is synthesized based on the relation between the load and motor speed. Finally, a PD-type iterative learning control law is applied for the desired motor position trajectory. Since the learning law applied for the desired trajectory guarantees the perfect tracking performance, the resulting load speed shows no vibration even when there exist model uncertainties. A modification to the learning law is also Presented to suppress undesired effects of an initial position error, The simulation results show the effectiveness of the proposed learning method.

Sequential Convex Programming Based Performance Analysis of UAV Design (순차 컨벡스 프로그래밍 기반 무인기 설계 형상의 성능 분석)

  • Ko, Hyo-Sang;Choi, Hanlim;Jang, Jong-Youn;Kim, Joon;Ryu, Gu-Hyun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.11
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    • pp.771-781
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    • 2022
  • Sequential convex programming based performance analysis of the designed UAV is performed. The nonlinear optimization problems generated by aerodynamics are approximated to socond order program by discretization and convexification. To improve the performance of the algorithm, the solution of the relaxed problem is used as the initial trajectory. Dive trajectory optimization problem is analyzed through iterative solution procedure of approximated problem. Finally, the maximum final velocity according to the performance of the actuator model was compared.