• 한국해양공학회지
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• 제26권3호
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• pp.20-25
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• 2012

In this paper, the authors propose a new approach to the control problem of marine vessels that are moored or controlled by actuators. The vessel control system is basically based on Dynamic Positioning System (DPS) technology. The main object of this paper is to obtain a more useful control design method for DPS. In this problem, the control allocation is a complication. For this problem, many results have been given and verified by other researchers using a two-step process, with the controller and control allocation design processes carried out individually. In this paper, the authors provide a more sophisticated design solution for this issue. The authors propose a new design method in which the controller design and control allocation problems are considered and solved simultaneously. In other words, the system stability, control performance, and allocation problem are unified by an LMI (linear matrix inequality) based on control theory. The usefulness of the proposed approach is verified by a simulation using a supply vessel model.

• Earthquakes and Structures
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• 제4권4호
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• pp.341-363
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• 2013

Earthquake response calculation, parametric analysis and seismic parameter optimization of base-isolated structures are some critical issues for seismic design of base-isolated structures. To calculate the earthquake responses for such non-symmetric and non-classical damping linear systems and to implement the earthquake resistant design codes, a modified complex mode superposition design response spectrum method is put forward. Furthermore, to do parameter optimization for base-isolation structures, a graphical approach is proposed by analyzing the relationship between the base shear ratio of a seismic base-isolation floor to non-seismic base-isolation one and frequency ratio-damping ratio, as well as the relationship between the seismic base-isolation floor displacement and frequency ratio-damping ratio. In addition, the influences of mode number and site classification on the seismic base-isolation structure and corresponding optimum parameters are investigated. It is demonstrated that the modified complex mode superposition design response spectrum method is more precise and more convenient to engineering applications for utilizing the damping reduction factors and the design response spectrum, and the proposed graphical approach for parameter optimization of seismic base-isolation structures is compendious and feasible.

• 한국CDE학회논문집
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• 제9권2호
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• pp.122-132
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• 2004

Progressive mesh representation and generation have become one of the most important issues in network-based computer graphics. However, current researches are mostly focused on triangular mesh models. On the other hand, solid models are widely used in industry and are applied to advanced applications such as product design and virtual assembly. Moreover, as the demand to share and transmit these solid models over the network is emerging, the generation and the transmission of progressive solid models depending on specific engineering needs and purpose are essential. In this paper, we present a Cellular Topology-based approach to generating and transmitting progressive solid models from a feature-based solid model for internet-based design and collaboration. The proposed approach introduces a new scheme for storing and transmitting solid models over the network. The Cellular Topology (CT) approach makes it possible to effectively generate progressive solid models and to efficiently transmit the models over the network with compact model size. Thus, an arbitrary solid model SM designed by a set of design features is stored as a much coarser solid model SM/sup 0/ together with a sequence of n detail records that indicate how to incrementally refine SM/sup 0/ exactly back into the original solid model SM = SM/sup 0/.

• Smart Structures and Systems
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• 제20권3호
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• pp.303-309
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• 2017

Structural control through seismic isolation using elastomeric rubber bearing, which is also known as High Damping Rubber Bearing (HDRB), has seen an increase in use to provide protective from earthquake, especially for new buildings in earthquake zones. Besides, HDRB has also been used in structural rehabilitation of older yet significant buildings, such as museums and palaces. However, the present design approach applied in normal practice has often resulted in dissimilar HDRB dimension requirement between structural designers and bearing manufacturers mainly due to ineffective communication. Therefore, in order to ease the design process, most HDRB manufacturers have come up with catalogs that list all necessary and relevant product lines specifically for structural engineers to choose from. In fact, these catalogs contain physical dimension, compression property, shear characteristic, and most importantly, the total rubber thickness. Nonetheless, other complicated issues, such as the relationship between target isolation period and displacement demand (which determines the total rubber thickness), are omitted due to cul-de-sac fixing of these values in the catalogs. As such, this paper presents a formula, which is derived and extended from the present design approach, in order to offer a simple guideline for engineers to estimate the required HDRB size. This improved design formula successfully minimizes the discrepancies stumbled upon among structural designers, builders, and rubber bearing manufacturers in terms of variation order issue at the designing stage because manufacturer of isolator is always the last to be appointed in most projects.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2004년도 춘계학술발표대회 논문집
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• pp.136-140
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• 2004

This study starts from the premise that future elementary school should be designed based on ecological approach. In order to restore the emotionality of children, school should provide and protect our natural environment by greening and energy saving. The research was conducted in Osaka and Busan to analyze the present condition of elementary schools in terms of ecology. The shared spaces such as halls, corridors, stairs and rest areas of fourteen schools were chosen and analyzed by the design analysis list. The list included the guidelines including greening, lighting, heating and cooling, ventilation and use of materials. The results showed that Korean schools require void space for more natural lighting, ventilation and insulation, while Japanese schools have problems in use of environmentally friendly materials, natural lighting and interior greening. This study reveals that ecological approach including greening and natural lighting should be considered in future elementary school design to make the school environment more agreeable and economical.

• Smart Structures and Systems
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• 제13권3호
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• pp.473-500
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• 2014

Tuned mass dampers (TMDs) have been installed in many high-rise buildings, to improve their resiliency under dynamic loads. However, high-rise buildings may experience natural frequency changes under ambient temperature fluctuations, extreme wind loads and relative humidity variations. This makes the design of a TMD challenging and may lead to a detuned scenario, which can reduce significantly the performance. To alleviate this problem, the current paper presents a proposed approach for the design of a robust and efficient TMD. The approach accounts for the uncertain natural frequency, the optimization objective and the input excitation. The study shows that robust design parameters can be different from the optimal parameters. Nevertheless, predetermined optimal parameters are useful to attain design robustness. A case study of a high-rise building is executed. The TMD designed with the proposed approach showed its robustness and effectiveness in reducing the responses of high-rise buildings under multidirectional wind. The case study represents an engineered design that is instructive. The results show that shear buildings may be controlled with less effort than cantilever buildings. Structural control performance in high-rise buildings may depend on the shape of the building, hence the flow patterns, as well as the wind direction angle. To further increase the performance of the robust TMD in one lateral direction, active control using LQG and fuzzy logic controllers was carried out. The performance of the controllers is remarkable in enhancing the response reduction. In addition, the fuzzy logic controller may be more robust than the LQG controller.

• 소성∙가공
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• 제16권3호
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• pp.172-177
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• 2007

The process design for large-scale ring rolling of Ti-6Al-4V alloy was performed by calculation method, processing map approach and FEM simulation. The ring rolling design includes geometry design and optimization of process variables. The calculation method was used to make geometry design such as initial billet and blank sizes, and final rolled ring shape. A commercial FEM code, SHAPE-RR was used to simulate the effect of process variables in ring rolling on the distribution of the internal state variables such as strain, strain rate and temperature. In order to predict the forming defects during ring rolling and the formation of over-heating above $\beta$-transus temperature due to deformation heating, the process-map approach based on Ziegler's instability criterion was used with FEM simulation. Finally, an optimum process design to obtain sound Ti-6Al-4V rings without forming defects was suggested through combined approach of Ziegler's instability map and FEM simulation results.

• 품질경영학회지
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• 제47권3호
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• pp.631-639
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• 2019

Purpose: In this paper we present a case study of applying quick and easy experimental design approach to develop a Halogen free flame retardant material for cellular phone charger cable. Methods: We employ sequential experimentation of mixture design, verification design, and factorial design. A quick and easy approach is adopted based on data investigation and graphical method instead of strict statistical analysis, which helped enhancing smooth communication with the engineers and speeding up the development process. Results: Flame retardant material in pellet type produced from the optimal condition is transported to the customer and tested, to pass the customer retardancy criteria. Conclusion: The quick and easy experimental design approach is considered to be useful in this case study.

• 대한건축학회논문집:계획계
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• 제34권4호
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• pp.77-85
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• 2018

Rapid urbanization has fostered development of modern cities. Although Conventional zoning played its role to control urban development, it also segregated land uses and created homogeneous development pattern. Mega cities with satellite bed towns has not shown their unique identity and characters. In order to develop comprehensive approach which may bring social and physical enhancement can be difficult to achieve by considering city as a two dimensions. On contrary, extensive analysis and proposals require an approach which can perceive city with three dimensions. Form-Based Codes (FBCs) are appeared as an alternative to conventional zoning with different design process and principles. FBCs approach urban place with three dimension and giving priority to form rather than land use. The purpose of this study was to analyze the necessity of FBCs and its concept, components and how this would change urban characteristics in the aspects of architectural design through analysis on 4 case studies for zoning codes of US cities. Through comparison of components in Form-Based Codes of 4 different cases, this study can show the reasons for differences in application of Form-Based Codes and how detailed components would play a role to establish better urban environments.

• Computers and Concrete
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• 제32권5호
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• pp.527-541
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• 2023

This paper emphasizes the use of CFT columns in frame structures subjected to strong horizontal forces and shows that the efficiency of using CFT columns is increased when the plastic design approach is adopted. Because the plastic design approach is based on redistribution of the force of the internal member, a double node for the rotational degrees of freedom, where the adjacent two rotational degrees of freedom can be connected by a non-dimensional spring element, is designed and implemented into the formulation. In addition, an accompanying criterion is considered in order to make it possible to describe the continuous moment redistribution in members connected to a nodal point up to a complete plastic state. The efficiency of CFT columns is reviewed in comparison with RC columns in terms of the cost and the resistance capacity, as defined by a P-M interaction diagram. Three representative frame structures are considered and the obtained results show that the most efficient and economical design can be expected when the use of CFT columns is considered on the basis of the plastic design, especially when a frame structure is subjected to significant horizontal forces, as in a high-rise building.