• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.601-606
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• 1992

In this paper, we consider an optimal guidance problem with both the terminal impact angle and control constraints in addition to the usual zero miss distance constraint. We first present the optimal solution of the problem for the missile of an arbitrary order, and show that it is a linear combination of a step response and a ramp response of the missile. Therefore the usual practice of using the control obtained by saturating the optimal solution for the case of unlimited control may result in a large terminal miss. A method called the initial command saturation is suggested to reduce this terminal miss, where the control in the initial phase of guidance is forced to be saturated until a certain condition for a guidance variable is met.

• Journal of Navigation and Port Research
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• v.30 no.3 s.109
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• pp.227-233
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• 2006

As North-east Chinese parts including Shanghai port grow rapidly, competition among the Far-East parts to be a hub port is getting higher, somebody has even raised a crisis of Busan port. However there are same constraints an the North-east parts such as weather aggravation and long distance from main truck routes. When we consider the competitiveness of port, weather aggravation should be considered as one of the significant factors. But previous studies have rarely examined these kinds of external factors of port operation Therefore, this study analyze constraints an the North-east Chinese parts through a survey of same national flag shipping companies and agencies of foreign shipping companies. The result shows that the mast significant constraint in the North-east ports is weather aggravation which causes problems for regular schedules of shipping, operation cast and customer service qualities etc.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.2
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• pp.154-169
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• 2012

This paper presents a comprehensive review of spacecraft guidance algorithms for asteroid intercept and rendezvous missions. Classical proportional navigation (PN) guidance is reviewed first, followed by pulsed PN guidance, augmented PN guidance, predictive feedback guidance, Lambert guidance, and other guidance laws based on orbit perturbation theory. Optimal feedback guidance laws satisfying various terminal constraints are also discussed. Finally, the zero-effort-velocity (ZEV) error, analogous to the well-known zero-effort-miss (ZEM) distance, is introduced, leading to a generalized ZEM/ZEV guidance law. These various feedback guidance laws can be easily applied to real asteroid intercept and rendezvous missions. However, differing mission requirements and spacecraft capabilities will require continued research on terminal-phase guidance laws.

• IE interfaces
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• v.19 no.4
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• pp.270-280
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• 2006

The shipping plan for an efficient augmentation of terminal is NP-hard problem which is subordinate to a shipping quantity. The load location problem and stowage planning problem are two important tactical problems for the efficient operations of container terminals. This paper is concerned with reduction of feasible region in constraints for stowage planning. After designing model which minimizes the number of shifting and the travel distance of the transfer crane, the simulated annealing algorithm is employed to search optimal solution quickly and accurately. In order to apply more realistic approach, the partial restriction through adding hatch is complemented to stowage planning decision problem applied in cluster. A variety of numerical experiments demonstrated that solutions by simulated annealing algorithm are useful and applicable in practice.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.3
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• pp.289-303
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• 2015

In this paper, an optimal guidance law with terminal angle constraint considering the seeker's lock-on condition, in which the target is located within the field-of-view (FOV) and detection range limits at the end of the midcourse phase, is proposed. The optimal solution is obtained by solving an optimal control problem minimizing the energy cost function weighted by a power of range-to-go subject to the terminal constraints, which can shape the guidance commands and the missile trajectories adjusting guidance gains of the weighting function. The proposed guidance law can be applied to both of the midcourse and terminal phases by setting the desired relative range and look angle to the final interception conditions. The performance of the proposed guidance law is analyzed through nonlinear simulations for various engagement conditions.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.46-53
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• 2007

In this paper, a guidance law for vision-based automatic landing of unmanned aerial vehicles (UAVs) is proposed. Automatic landing is a challenging but crucial capability for UAVs to achieve a fully autonomous flight. In an autonomous landing maneuver of UAVs, the decision of where to landing and the generation of guidance command to achieve a successful landing are very significant problem. This paper is focused on the design of guidance law applicable to automatic landing problem of fixed-wing UAV and rotary-wing UAV, simultaneously. The proposed guidance law generates acceleration command as a control input which derived from a specified time-to-go ($t_go$) polynomial function. The coefficient of $t_go$-polynomial function are determined to satisfy some terminal constraints. Nonlinear simulation results using a fixed-wing and rotary-wing UAV models are presented.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.1
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• pp.14-24
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• 2002

We focus on resource allocation planning in container terminal operation planning problems and present network design model and genetic algorithm. We present a network design model in which arc capacities must be properly dimensioned to sustain the container traffic. This model supports various planning aspects of container terminal and brings in a very general form. The integer programming model of network design can be extended to accommodate vertical or horizontal yard configuration by adding constraints such as restricting the sum of yard cranes allocated to a block of yards. We devise a genetic algorithm for the network design model in which genes have the form of general integers instead of binary integers. In computational experiments, it is found that the genetic algorithm can produce very good solution compared to the optimal solution obtained by CPLEX in terms of computation time and solution quality. This algorithm can be used to generate many alternatives of a resource allocation plan for the container terminal and to evaluate the alternatives using various tools such as simulation.

• Journal of information and communication convergence engineering
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• v.19 no.2
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• pp.114-119
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• 2021

This paper proposes a method to find an optimal T' with the most terminal of the subset of T' trees that can be connected by a given length by improving a memetic genetic algorithm within several constraints, when the set of terminal T is given to the Euclidean plane R². Constraint (1) is that a given length cannot connect all terminals of T, and (2) considers only the rectilinear layout of the edge connecting each terminal. The construction of interconnections has been used in various design-related areas, from network to architecture. Among these areas, there are cases where only the rectilinear layout is considered, such as wiring paths in the computer network and VLSI design, network design, and circuit connection length estimation in standard cell deployment. Therefore, the heuristics proposed in this paper are expected to provide various cost savings in the rectilinear layout.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.165-171
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• 2006

The appearance of over 10,000 TEU containerships (so called Mega-containerships) is determined. In order to operate these ships effectively, the number of these calling ports will diminish, and then feeder ships will transport cargoes from the hub-ports where mega-containerships call to the destination ports. In the hub-ports, handling containers for mega-containerships become huger, thus it is important for terminals to deal with cargo handling as soon as possible. However, the present terminal layout might have the limitation of maximum throughput per time unit. And then the transit time at the ports become longer. Therefore, we investigate the effect on some different terminal layouts with new alternatives. Actually, we discuss the ship-to-berth allocation at some adjacent berths for mega-containerships on three types of terminal layouts. First one is the conventional type consisted by some linear berths, most container terminals in the world are normally this type. Second one is the indented type consisted by linear berths and indented berths which we can handle from both sides of mega-containership simultaneously. Third one is the floating type consisted by linear berths and the floating berth. On this type, mega-containerships can moor between linear and floating berths. The merits of this type are that we can also handle from both sides of mega-containerships simultaneously, and ships can go through between linear berth and floating berths. Thus it is easier for ships to moor and leave berths. Under such assumptions, we examine the numerical experiments. In most cases, the total service times on the indented type are the longest among three types, these on the floating type are the next longer. Those reasons are that these layouts have the differences of berth occupancy obtained by the time and space axes, and whether the precedence constraints of ship service order needs or not.

• Industrial Engineering and Management Systems
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• v.9 no.2
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• pp.178-194
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• 2010

To improve the ship operation in automated container terminals, it is important to schedule different types of handling equipment to operate synchronously. For example, a vehicle with container receiving and lifting capabilities is used to transport containers from a storage yard to a vessel and vice versa, while a triple quay crane (QC) can handle up to three 40-ft containers simultaneously. This paper discusses the manner in which vehicles should be assigned to containers to support such multi-lifts of QCs by using information about the locations and times of deliveries. A mixed-integer programming model is introduced to optimally assign delivery tasks to vehicles. This model considers the constraint imposed by the limited buffer space under each QC. A procedure for converting buffer-space constraints into time window constraints and a heuristic algorithmfor overcoming the excessive computational time required for solving the mathematical model are suggested. A numerical experiment is conducted to compare the objective values and computational times of the heuristic algorithm with those of the optimizing method to evaluate the performance of the heuristic algorithm.