• International Journal of Aeronautical and Space Sciences
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• v.15 no.2
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• pp.190-198
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• 2014

The pyramidal reaction wheel arrangement is one of the configurations that can be used in attitude control simulators for evaluation of attitude control performance in satellites. In this arrangement, the wheels are oriented in a pyramidal configuration with a tilt angle. In this paper, a study of pyramidal reaction wheel arrangement is carried out in order to find the optimum tilt angle that minimizes total power consumption of the system. The attitude control system is analyzed and the pyramidal configuration is implemented in numerical simulation. Optimization is carried out by using an iterative process and the optimum tilt angle that provides minimum system power consumption is obtained. Simulation results show that the system requires the least power by using optimum tilt angle in reaction wheels arrangement.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1678-1680
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• 1998

The purpose of this study is to obtain optimum arrangement of phase conductors in minimizing magnetic field from overhead transmission lines. Data of the transmission lines rated 345 kV of the KEPCO(Korea Electric Power Company)'s system were used. For a three phase-double circuit transmission line, low-reactance arrangement is optimum in minimizing magnetic fields. For a three phase-four circuit, optimum phase arrangement is a-b-c-b-a-c(lower two circuits, clockwise)/b-c-a-c-a-b(upper two circuits, clockwise).

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.918-925
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• 2017

Multiple reflections on exterior equipment with complex shape on naval ships cause unexpectedly high Radar Cross Section (RCS) distributions, and the directions of reradiated electromagnetic waves are hard to predict. Therefore, the optimum arrangement of exterior equipments should be considered according to the Radar Absorbing Structure (RAS) method. In this paper, the optimum arrangement for exterior equipments was determined to reduce multiple reflections and RCS even with complex shapes. The sequential descending arrangement method was used to establish an optimum arrangement algorithm. An LCS-2 type model was selected for optimum exterior equipment arrangements. In order to reduce computational cost, RCS distributions and multiple reflection path analysis of exterior equipments was carried out to select exterior equipments for optimum arrangement, and an optimum arrangement was determined to find positions with minimum RCS values. Also, the RCS reduction effect was analyzed using detectable radar range.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.3-7
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• 2001

Although elbows are commonly used in practice, many questions regarding the optimum arrangement still remain unanswered. The effect due to an elbow lasts for a considerable distance downstream of the elbow and is severe when two elbows are in the system. The goal of this study is to provide an effective guide for the optimum arrangement of elbows and the optimum design of the approach piping system.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.1
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• pp.59-68
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• 2013

Nowadays, optimum structural design techniques based on CSR have been developed and applied to the preliminary design stage focused on minimum weight and minimum construction cost of ship structure. Optimum structural design algorithm developed before could minimize weight and cost on fixed compartment arrangement. However, to develop more efficient design technique, a designer needs to combine optimized compartment arrangement with optimized ship structural design because compartment arrangement has a large effect on structural design according to the change of still water bending moment as a consequence of compartment arrangement change. In this study, automated algorithm for compartment arrangement of an oil tanker is developed to apply preliminary structural design. The usefulness of developed algorithm is verified with Aframax oil tanker constructed by STX shipbuilding Co.Ltd..

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.397-402
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• 2003

Generally, container arrangement has been carried out based on the Classification guidelines. However, guidelines provide only container securing forces for the given container arrangement and Classification requirements of the forces. In order to design container arrangement additional information is needed such as container securing forces and arrangement that accounts for lashing bridges, vertical lashing, vertical center of gravity (VCG), and maximum stack weight. Trial and error method using the existing guidelines requires excessive amount of calculation time and cannot provide accurate results of the calculations. In order to fulfill this need, a new container securing system has been established based on the equilibrium conditions that include lashing bridges and vertical lashing. An optimization algorithm has been developed for the new system since current optimization methods such as genetic algorithms and evolution strategies are unsuitable for the container securing problems, which involve equality constraint. Design variables are container weights of tier and objective function is either total container weight or VCG of a stack. The newly developed system provides optimum arrangement of containers for both maximum stack weight and maximum VCG. It also greatly reduces time for designing container arrangement.

• Journal of Ocean Engineering and Technology
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• v.30 no.1
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• pp.10-17
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• 2016

This paper reports a simulation-based design method for the optimized arrangement design of buoyancy modules in a marine riser system. A buoyancy module is used for the safe operation and structural stability of the riser. Engineers design buoyancy modules based on experience and experimental data. However, they are difficult to design because of the difficulty of conducting real sea experiments and quantifying the data. Therefore, a simulation-based design method is needed to tackle this problem. In this study, we developed a simulation-based design algorithm using a multi-body dynamic simulation and genetic algorithm to perform optimization arrangement design of a buoyancy module. The design results are discussed in this paper.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.4
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• pp.298-304
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• 2015

Shipboard equipment in naval ships should be designed to be safe under the shock load. Very high stress due to the shock load can be effectively reduced by the resilient mounts considering the mount capacity and dynamic characteristics. An optimum arrangement of resilient mount installed to absorb the shock energy is addressed to assess the safety of ship structure and shipboard equipment subjected to the shock load. Structural responses are analyzed for both frame structure supporting the shipboard equipment subject to the shock load with and without the resilient mounts. The shock absorbability of the resilient mount is evaluated by the results of structural response analysis; meanwhile, several types of shock analyses considering the arrangement of resilient mounts are carried out and the shock responses are compared to verify the effect of the arrangement. Thereafter, optimum arrangements are obtained by means of Genetic algorithm (GA) considering the different capacities of resilient mount. Stress, deformation and dynamic feature at the frame structure supporting the shipboard equipment under the shock load are also discussed in order to meet the capacity of resilient mount.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.2
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• pp.138-147
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• 2014

This paper proposed an application of expert system to submarine arrangement design. Since all components of the submarine should be placed in a restricted place called pressure hull, expert knowledge has great effects on design of submarine arrangement. In this regard, a suitable knowledge-based expert system shell was applied to design of submarine arrangement process. To use expert system on the design of submarine arrangement effectively, a template model for submarine arrangement, which is proper to use in optimum design process, was developed. The proposed system was applied to simplified example of submarine arrangement problem to choose optimal design alternative. From this study, it was verified that expert system could be used in design of submarine arrangement with effect.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.741-748
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• 2006

This paper numerically investigates the effects of pass arrangement on the flow distribution characteristics and the performance of a multi-pass multi-branch heat exchanger. Four cases of pass arrangement (2, 4, 6, 8 pass) are chosen to select a proper pass arrangement. A JF factor is used as an evaluation characteristic value to consider the heat transfer and the pressure drop. The present results indicate that 4-pass heat exchanger shows the best performance, and the design parameters in 4-pass heat exchanger are optimized. The design parameters are the locations of the inlet, outlet and separator, and are optimized using a response surface methodology. The JF factor of the optimum model is increased by about 9.3%, compared to that of the reference model (2-pass heat exchanger).