• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.144-152
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• 2011

The existing underground trenchless methods use reinforcing rod in steel tube to obtain structural stiffness. However, there are some problems such as inconvenience of work and expensive material fee which are resulted from limited working space and reinforcing work. To resolve these problems, a new trenchless method, namely P.S.T method (Prestressed Segment Tunnel Method), is developed which uses joint to connect the steel segment and form erection structure in underground construction. Further, installing strands for prestressing. In order to evaluate the flexural capacity of the P.S.T method structure, experiment was conducted. The parameters considered in the experiment are the span-to-depth ratio, diameter of steel tube at corner, prestressing force and welding of joint. Altogether examining the flexural behavior, the effect of deflection in structure according to different parameters has also been analysised.

• Structural Engineering and Mechanics
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• v.56 no.5
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• pp.707-726
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• 2015

There is a growing trend of considering uncertainty in optimization process since last few decades. In this regard, Robust Design Optimization (RDO) scheme has gained increasing momentum because of its virtue of improving performance of structure by minimizing the variation of performance and ensuring necessary safety and feasibility of constraint under uncertainty. In the present study, RDO of reinforced concrete folded plate and shell structure has been carried out incorporating uncertainty in the relevant parameters by Monte Carlo Simulation. Folded plate and shell structures are among the new generation popular structures often used in aesthetically appealing constructions. However, RDO study of such important structures is observed to be scarce. The optimization problem is formulated as cost minimization problem subjected to the force and displacements constraints considering dead, live and wind load. Then, the RDO is framed by simultaneously optimizing the expected value and the variation of the performance function using weighted sum approach. The robustness in constraint is ensured by adding suitable penalty term and through a target reliability index. The RDO problem is solved by Sequential Quadratic Programming. Subsequently, the results of the RDO are compared with conventional deterministic design approach. The parametric study implies that robust designs can be achieved by sacrificing only small increment in initial cost, but at the same time, considerable quality and guarantee of the structural behaviour can be ensured by the RDO solutions.

• Interaction and multiscale mechanics
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• v.3 no.2
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• pp.192-211
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• 2010

In most framed structures the nonlinearities and the damages are localized, extending over a limited length of the structural member. In order to capture the details of the local damage, the segments of a member that have entered the nonlinear range may need to be analyzed using the three-dimensional element (3D) model whereas the rest of the member can be analyzed using the simpler one-dimensional (1D) element model with fewer degrees of freedom. An Element-Coupling model was proposed to couple the small scale solid 3D elements with the large scale 1D beam elements. The mixed dimensional coupling is performed imposing the kinematic coupling hypothesis of the 1D model on the interfaces of the 3D model. The analysis results are compared with test results of a reinforced concrete pipe column and a structure consisting of reinforced concrete columns and a steel space truss subjected to static and dynamic loading. This structure is a reduced scale model of a direct air-cooled condenser support platform built in a thermal power plant. The reduction scale for the column as well as for the structure was 1:8. The same structures are also analyzed using 3D solid elements for the entire structure to demonstrate the validity of the Element-Coupling model. A comparison of the accuracy and the computational effort indicates that by the proposed Element-Coupling method the accuracy is almost the same but the computational effort is significantly reduced.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.52-59
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• 2015

In this paper, the vibration control effect of the isotropic damping devices (so-called Kagome dampers) was investigated by applying the Kagome dampers to a 20-story frame structure apartment. A new Kagome Damper System (KGDS) composed of the dampers and supporting column was proposed and numerical analyses were performed to investigate the effects of stiffness ratio between controlled structure and supporting column, the damper size and the number of the dampers. The numerical analysis results of a structure with KGDS up to the third story showed that the stiffness ratio should be higher than 6.4 and the damper size be at least $700{\times}700mm$ to effectively reduce the base shear and the maximum drift of the uppermost story. When the KGDS was installed up to the fifth story, the stiffness ratio should be higher than 7.0 and damper size needs to be at least $500{\times}500mm$ for obtaining the target performance.

• Journal of the Korea Furniture Society
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• v.21 no.3
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• pp.216-228
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• 2010

Recently, there is a new issue, among the contemporary people, for new life style, such as green design and well being. This trend brought up the necessity that there should be alternatives for interior spatial design. In order to catch up with these new issues, the new convenient and environment friendly methods are in need. Space composition using setting-up is skill that can express both the structural aspect and esthetic because it represents traditional beauty into the contemporary age through the structural rigidity and formal beauty. Also the lumber, as main materials for setting up, is in line with well being life style and environment friendliness. The construction of structure by setting-up has advantages in terms of the reuse and the convenience in that the construction of structure is adjustable according to environment. And setting-up has enough plasticity not only because of its own role as linking the objects but also because of being framed by itself. Therefore setting-up will be a design element, if it is expressed outward. Thus, this study aims to give a guide line about how to apply the result from the evaluating that "what is the most suitable setting-up" and "what is the most suitable detail setting-up", based on that structural rigidity, decorativeness and the ease of works. As a result of evaluation, the most excellent types of setting-up in terms of structural rigidity are "Jangbu" and "Panjae" and "Yeongui". The most excellent types of setting-up in terms of decorativeness are "Panjae" and "Yeongui", and the most excellent type of the ease of work is "Mat". And also the most applicable detail setting-up for the utilization of spatial composition is proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.2
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• pp.104-112
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• 2012

The failure of tenon in a traditional wood-framed structure may collapse of the entire structure. This study evaluates the strength and stiffness of tenon joints between the beams and pillars through experimental study and suggests reinforcing method of the tenon joint without dismantling the main structures. The main experimental parameters are the number, distance, shape, and inserting depth of spiral-shaped reinforcing steels. As the thickness of the tenon in beams increases, the strength and the initial shear stiffness of the joint increases and, however, the tenons in pillar becomes weaker, resulting in the safety problem of the structure. It is recommended that three spiral-shaped reinforcing steels be placed in the central parts of the tenon to effectively improve the strength and the shear stiffness of the joint.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.3
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• pp.133-140
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• 2014

The friction damper can be used for improving the seismic resistance of existing buildings. The damper is often installed in bracing members. The energy dissipation capacity of the damping systems depends on the type of the structure, the configuration of the bracing members, and the property of dampers. In Korea, there are numerous low- to mid-rise reinforced concrete moment frames that were constructed considering only gravity loads. Those frames may be vulnerable for future earthquakes. To resolve the problem, this study developed a toggle bracing system with a high density friction damper. To investigate the improvement of reinforced concrete frames after retrofit using the developed damped system, experimental tests were conducted on frame specimens with and without the damped system. The results showed that the maximum strength, initial stiffness and energy dissipation capacity of the framed with the damped system were much larger than those of the frame without the damped system.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.189-192
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• 2000

This paper proposes a fuzzy-based random access controller with a superimposed frame structure (F$^2$RAC) fur voice/data-integrated wireless networks. F$^2$RAC adopts mini-slot technique for reducing contention cost, and these mini-slots of which number may dynamically vary from one frame to the next as a function of the traffic load are further partitioned into two regions for access requests coming from voice and data traffic with their respective QoS requirements. And F$^2$RAC is designed to properly determine the access regions and permission probabilities for enhancing the data packet delay while ensuring the voice packet dropping probability constraint. It mainly consists of the estimator with Pseudo-Bayesian algorithm and fuzzy logic controller with Sugeno-type of fuzzy rules. Simulation results prove that F$^2$RAC can guarantee QoS requirement of voice and provide the highest throughput efficiency and the smallest data packet delay amongst the different alternatives including PRMA［1］, IPRMA［2］, and SIR［3］.

• Korean Institute of Interior Design Journal
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• v.14 no.5 s.52
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• pp.44-51
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• 2005

This study focuses 'Korean characteristics' in architectural interior design. In this study, some Korean characteristics was extracted by analysing traditional Korean spaces and as well as by considering the architectural interior spaces which are designed with Korean character since 1970. This paper started with differenciating the elements and principles that consist of space, and then classified the elements into 8 categories such as Spatial system, Enclosure system, Circulation system, Material system, Furnishing system, Light, Color, Context which are analysing frames. As a conclusion, the concepts of Korean characteristics are extracted and suggested as design concept with Korean characteristics by analysing the contents of each category. These concepts were presented with simple diagrams and supporting cases were also presented in this paper. The design concepts of 'Korean characteristics' are classified in the 25 concepts: Holonic composition, Transitional space, Hierarchy by floor level, Gradation of privacy, Changeability, Various central yards, Space with opened edges, Gray space, Continuity of space, Translucent wall, Folding-lifting wall, Skeleton, Abstract facet, Path as a message, Mild light, Multii-layered vista, Fluidity, framed scenery, Serial view, Interpenetrating Space, Harmony with nature, Organic interrelationship, Complementary Dual Structure, Temporal change of space, Hierarchical order.

• Journal of Korean Library and Information Science Society
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• v.32 no.3
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• pp.31-58
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• 2001

The objective of this study was to provide the basic information necessary for the efficient library service policy for the graduate students in engineering field as investigating the academic information seeking behavior and demands of users who major in electronic engineering at a graduate program. Literature studies and survey through questionnaire were conducted for the purpose. The established theories were synthetically examined through literature studies, and theoretical systematization and structure for positive research were framed. Graduate students in engineering field were classified into two groups: those who major in electronic engineering and the others, and their demands for information and its seeking behavior were comparatively analyzed in this thesis.