• Bulletin of the Korean Space Science Society
• /
• 2005.10a
• /
• pp.65-65
• /
• 2005

• Bulletin of the Korean Space Science Society
• /
• 2004.10b
• /
• pp.77-77
• /
• 2004

• International Journal of Aeronautical and Space Sciences
• /
• v.16 no.3
• /
• pp.347-359
• /
• 2015

A method of describing the rovibrational energy transitions and coupled chemical reactions in the direct simulation Monte Carlo (DSMC) calculations is constructed for $H(^2S)+H_2(X^1{\Sigma}_g)$ and $He(^1S)+H_2(X^1{\Sigma}_g)$. First, the state-specific total cross sections for each rovibrational states are proposed to describe the state-resolved elastic collisions. The state-resolved method is constructed to describe the rotational-vibrational-translational (RVT) energy transitions and coupled chemical reactions by these state-specific total cross sections and the rovibrational state-to-state transition cross sections of bound-bound and bound-free transitions. The RVT energy transitions and coupled chemical reactions are calculated by the state-resolved method in various heat bath conditions without relying on a macroscopic properties and phenomenological models of the DSMC. In nonequilibrium heat bath calculations, the state-resolved method are validated with those of the master equation calculations and the existing shock-tube experimental data. In bound-free transitions, the parameters of the existing chemical reaction models of the DSMC are proposed through the calibrations in the thermochemical nonequilibrium conditions. When the bound-free transition component of the state-resolved method is replaced by the existing chemical reaction models, the same agreement can be obtained except total collision energy model.

• Bulletin of the Korean Space Science Society
• /
• 1997.04a
• /
• pp.36.2-36
• /
• 1997

No Abstract.See Full-text

• The Bulletin of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.44.2-44.2
• /
• 2005

• Journal of Korea Multimedia Society
• /
• v.3 no.1
• /
• pp.77-90
• /
• 2000

Real-Time verification is a procedure that verifies the correctness of specification related to requirement in time as well as in logic. One serious problem encountered in the verification task is that the state space grows exponentially owing to the unboundedness of time, which is termed the state space explosion problem. In this paper, we propose a real-time verification technique checking the correctness of specification by showing that a system model described in timed automata is equivalent to the characteristic of system property specified in timed modal-mu calculus. For this, we propose a local model checking method based on the value of the formula in initial state with constructing product graph concerned to only the nodes needed for verification process. Since this method does not search for every state of system model, the state space is reduced drastically so that the proposed method can be applied effectively to real-time system verification.

• Structural Engineering and Mechanics
• /
• v.34 no.6
• /
• pp.739-753
• /
• 2010

Pointing to the design requirement of prestressed space grid structure being the target cable force, the pretension scheme decision analysis method is studied when there's great difference between structural actual state and the analytical model. Based on recursive formulation of cable forces, the simulative recursive system for pretension process is established from the systematic viewpoint, including four kinds of parameters, i.e., system initial value (structural initial state), system input value (tensioning control force scheme), system state parameters (influence matrix of cable forces), system output value (pretension accomplishment). The system controllability depends on the system state parameters. Based on cable force observation values, the influence matrix for system state parameters can be calculated, making the system controllable. Next, the pretension scheme decision method based on cable force observation values can be formed on the basis of iterative calculation for recursive system. In this way, the tensioning control force scheme that can meet the design requirement when next cyclic supplemental tension finished is obtained. Engineering example analysis results show that the proposed method in this paper can reduce a lot of cyclic tensioning work and meanwhile the design requirement can be met.

• International Journal of Aeronautical and Space Sciences
• /
• v.15 no.2
• /
• pp.163-172
• /
• 2014

This paper proposes a novel guidance law based on the block backstepping sliding mode control and extended state observer (ESO), which also takes into account the autopilot dynamic characteristics of the near space interceptor (NSI), and the impact angle constraint of attacking the maneuvering target. Based on the backstepping control approach, the target maneuvers and the parameter uncertainties of the autopilot are regarded as disturbances of the outer loop and inner loop, respectively. Then, the ESO is constructed to estimate the target acceleration and the inner loop disturbance, and the block backstepping sliding model guidance law is employed, based on the estimated disturbance value. Furthermore, in order to avoid the "explosion of complexity" problem, first-order low-pass filters are also introduced, to obtain differentiations of the virtual control variables. The stability of the closed-loop guidance system is also proven, based on the Lyapunov theory. Finally, simulation results demonstrate that the proposed guidance law can not only overcome the influence of the autopilot dynamic delay and target maneuvers, but also obtain a small miss distance.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.2
• /
• pp.670-683
• /
• 2016

Network coding, as a new technique to improve the throughput, is studied combined with multi-relay model in this paper to address the challenges of long distance and power limit in deep space communication. First, an amplify-and-forward relaying approach based on analog network coding (AFNC) is proposed in multi-relay network to improve the capacity for deep space communication system, where multiple relays are introduced to overcome the long distance link loss. The design of amplification coefficients is mathematically formulated as the optimization problem of maximizing SNR under sum-power constraint over relays. Then for a dual-hop relay network with a single source, the optimal amplification coefficients are derived when the multiple relays introduce non-coherent noise. Through theoretic analysis and simulation, it is shown that our approach can achieve the maximum transmission rate and perform better over single link transmission for deep space communication.

• The Journal of Korean Academy of Prosthodontics
• /
• v.13 no.1
• /
• pp.11-22
• /
• 1975

This study is to determine the severity and direction of the movement of the adjacent tooth into the created space by tooth or teeth loss. The random samples 387 cases (upper; 121 cases, lower; 266 cases) were selected with surveying record under some criteria. Edentulous area is grouped into the free end type and the tooth borne type. The following results were obtained. In the tooth borne type, slight distal movement of the adjacent tooth into the edentulous space was obtained. And the tooth distal to the edentulous space moved into the space in proportion to the duration of the edentulous state. Elongation of the opposing tooth of the free end type was more severe than that of the tooth borne type. And no inter-relationship between the severity of the elongation and the duration of the edentulous state In general, adjacent teeth had normal and mesial inclination. Lower teeth migrated mesially and lingually (especially in the distal tooth to the edentulous space in the tooth borne type). Upper adjacent teeth usually moved into the normal direction.