Chang-Hun Lee

The work presented here investigates proposed impact angle control guidance laws with terminal acceleration constraints for a stationary or slowly moving target. These laws, called time-to-go polynomial guidance (TPG), assume the guidance command as a polynomial function of time-to-go and determine the coefficients of the guidance command to satisfy the specified terminal constraints. The closed-form trajectory solutions of the guidance command and the target look angle for lag-free systems are

Purpose The purpose of this paper is to understand how the development of social capital can promote buyer’s bi-directional (inflow and outflow) information sharing. The authors examined buyers’ perceptional differences in information sharing: when they receive information from suppliers and when they provide information to suppliers, and how such inequivalent perception in information sharing can be resolved by the level of social capital and its’ sub-dimensions. Design/methodology/approach The

The generalized formulation of weighted optimal guidance laws with impact angle constraint is investigated here. From the generalized formulation, we explicitly find the feasible set of weighting functions that lead to analytical forms of weighted optimal guidance laws. This result has potential significance because it can provide additional degrees of freedom in designing a guidance law that accomplishes the specified guidance objective.

Despite the emerging phenomenon of sexting, scientific investigation with criminological perspectives has been limited. Utilizing data collected from 1,612 randomly selected youth in South Korea, this study begins the investigation into which criminological theory best explains sexting behaviors. Theories considered include self-control, social control, and social learning theories. Some variables of each of those theories were tested. Findings showed that peer pressure was the most important fa

This paper proposes a new three-dimensional optimal guidance law for impact time control with seeker’s Field-of-View (FOV) constraint to intercept a stationary target. The proposed guidance law is devised in conjunction with the concept of biased Proportional Navigation Guidance (PNG). The guidance law developed leverages a nonlinear function to ensure the boundedness of velocity lead angle to cater to the seeker’s FOV limit. It is proven that the impact time error is nullified in a finite-time

In this article, a new impact angle control guidance law for a stationary or slowly moving target is developed using the high-performance sliding mode control methodology. The law can produce various missile trajectories by changing the damping ratio of the guidance loop motion during interception in order to achieve not only the satisfaction of the terminal impact angle constraint but also the additional guidance objectives. Since the proposed guidance law is given using the general function te

This paper deals with a nonlinear adaptive autopilot design for agile missile systems. During the agile turn, there exist highly nonlinear, rapidly changing dynamics and aerodynamic uncertainties. To handle these difficulties, we propose a longitudinal autopilot for angle-of-attack tracking based on backstepping control methodology in conjunction with the time-delay adaptation scheme. The performance of the proposed method is investigated through nonlinear 6-DOF simulations using a reference ang

This paper proposes a biased proportional navigation guidance (BPNG) law providing enhanced target observability for passive homing missile systems against a nonmaneuvering target. After examining the line-of-sight (LOS) rate equation, which is an important parameter of target observability and which reveals that the LOS rate is proportional to the rate of cross-range deviation, a bias term of BPNG is formulated using the rate of cross-range deviation to generate an additional LOS rate. The clos

This paper suggests a new approach in designing homing guidance laws to enable direct shaping of the pattern of zero-effort-miss (ZEM) as desired. The proposed approach uses the concept of weighted ZEM and its specific desired error dynamics: the former is to provide an additional degree of freedom in shaping actual ZEM and the latter is to guarantee a finite-time convergence. Utilization of these two concepts allows simple determination of the guidance law that can achieve the desired pattern o

This paper deals with a new passive homing guidance law for a stationary or a slowly moving target using sliding mode control technique. The proposed guidance law is designed in such a way of increasing the target observability. In addition, it can control a terminal impact angle to maximize warhead effect. The main idea is that we design the nonlinear sliding surface which makes an oscillatory missile motion along the desired impact angle frame so that the proposed guidance law introduces the L

In this paper, new optimal guidance laws for a stationary or a slowly moving target are proposed by solving the optimal control problem with the energy performance index weighted by sinusoidal functions. This weighting function is adopted to shape the specific guidance command: introducing a small acceleration at the initial and final time. This property is desirable for reducing the sensitivity against the initial heading error and improving terminal guidance performance. Numerical simulations