• Geomechanics and Engineering
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• v.4 no.3
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• pp.191-208
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• 2012

Due to rapid industrialisation, large scale infrastructure development is taking place worldwide. This includes railways, high speed highways, elevated roads etc. To meet the demands of society and industry, many innovative techniques and materials are being developed. In developed nations like USA, Japan etc. for railways applications, new material like geocells, geogrids are being used successfully to enable fast movement of vehicles. The present research work was aimed to develop design methodologies for improvement of grounds subjected to cyclic loads caused by moving vehicles on roads, rail tracks etc. Deformation behavior of ballast under static and cyclic load tests was studied based on square footing test. The paper presents a study of the effect of geo-synthetic reinforcement on the (cumulative) plastic settlement, of point loaded square footing on a thick layer of granular base overlying different compressible bases. The research findings showed that inclusion of geo-synthetics significantly improves the performance of ballasted tracks and reduces the foundation area. If the area is kept same, higher speed trains can be allowed to pass through the same track with insertion of geosynthetics. Similarly, area of machine foundation may also be reduced where geosynthetics is provided in foundation. The model tests results have been validated by numerical modeling, using $FLAC^{3D}$.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1669-1679
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• 2017

Background: Steam generator (SG) is one of the significant components in the nuclear steam supply system. A variety of SGs have been designed and used in nuclear reactor systems. Every SG has advantages and disadvantages. A brief account of some of the existing SG designs is presented in this study. A high surface to volume ratio of a SG is required in small modular reactors to occupy the least space. In this paper, performance improvement for SGs of integral small modular reactor is proposed. Aims/Methods: For this purpose, cross-grooved microfins have been incorporated on the inner surface of the helical tube to enhance heat transfer. The primary objective of this work is to investigate thermal-hydraulic behavior of the proposed improvements through modeling in RELAP5-3D. Results and Conclusions: The results are compared with helical-coiled SGs being used in IRIS (International Reactor Innovative and Secure). The results show that the tube length reduces up to 11.56% keeping thermal and hydraulic conditions fixed. In the case of fixed size, the steam outlet temperature increases from 590.1 K to 597.0 K and the capability of power transfer from primary to secondary also increases. However, these advantages are associated with some extra pressure drop, which has to be compensated.

• Journal of the Korea Furniture Society
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• v.27 no.1
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• pp.49-58
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• 2016

In modern society, designers started feeling moral and social responsibility in the aspect of environment as a position of suggesting something new. Rather than creating another waste to make something innovative, the concept of Upcycling which is about adding design or utilization to the existing recyclable materials to raise their value to products or art works has started settling down. Among them, there have been various researches on the use of offcut waste to be dumped. Such use of waste can be found in Jogakbo (patchwork), one of our traditional boudoir crafts. This could be connected to the concept of the modern Upcycling in the aspect of giving new values to the wasted pieces of fabric through needlework. Therefore, this study suggested Stitch work as new Upcycling furniture by seeking for the common connections between Upcycling and traditional Jogakbo, and then reinterpreting them in the same viewpoint. It was an opportunity not only to rediscover 'the esthetics of waste' by changing the awareness of 'behavior of dumping', but also to reinterpret or reconsider the tradition. Based on this, it is expected to continuously have new attempts to use offcut waste for eco-friendly design in the future, and also to have opportunities to seek for new directions of Upcycling to rediscover new values through the revaluation of valuelessness.

• Steel and Composite Structures
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• v.31 no.3
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• pp.217-232
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• 2019

Modular steel buildings consist of prefabricated room-sized structural units that are manufactured offsite and installed onsite. The inter-module connections must fulfill the assembly construction requirements and soundly transfer the external loads. This work proposes an innovative assembled connection suitable for modular buildings with concrete-filled steel tube columns. The connection uses pretensioned strands and plugin bars to vertically connect the adjacent modular columns. The moment-transferring performance of this inter-module connection was studied through monotonic and cyclic loading tests. The results showed that because of the assembly construction, the connected sections were separated under lateral bending, and the prestressed inter-module connection performed as a weak semirigid connection. The moment strength at the early loading stage originated primarily from the contact bonding mechanism with the infilled concrete, and the postyield strength depended mainly on the tensioned strands. The connection displayed a self-centering-like behavior that the induced deformation was reversed during unloading. The energy dissipation originated primarily from frictional slipping of the plugin bars and steel strands. The moment transferring ability was closely related to the section dimension and the arrangements of the plugin bars and steel strands. A simplified strength calculation and evaluation method was also proposed, and the effectiveness was validated with the test data.

• Computers and Concrete
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• v.32 no.1
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• pp.87-97
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• 2023

The bending of a porous FG plate is discussed in this study using a novel higher quasi-3D hyperbolic shear deformation theory with four unknowns. The proposed theory takes into consideration the normal and transverse shear deformation effect and ensures the parabolic distribution of the transverse stresses through the thickness direction with zero-traction at the top and the bottom surfaces of the structure. Innovative porous functionally graded materials (FGM) have through-thickness porosity as a unique attribute that gradually varies with their qualities. An analytical solution of the static response of the perfect and imperfect FG plate was derived based on the virtual work principle and solved using Navier's procedure. The validity and the efficiency of the current model is confirmed by comparing the results with those obtained by others solutions. The comparisons showed that the present model is very efficient and simple in terms of computation time and exactness. The impact of the porosity parameter, aspect ratio, and thickness ratio on the bending of porous FG plate is shown through a discussion of several numerical results.

• Composites Research
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• v.17 no.6
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• pp.22-27
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• 2004

The objective of this work is to design Surface Antenna Structure (SAS) and investigate fatigue behavior of SAS that is asymmetric sandwich structure. This term, SAS, indicates that structural surface becomes antenna. Constituent materials are selected considering electrical properties, dielectric constant and tangent loss as well as mechanical properties. For the antenna performance, SSSFIP elements inserted into structural layers were designed fur satellite communication at a resonant frequency of 12.5 GHz and final demonstration article was $16{\;}{\tiems}{\;}8$ array antenna. From electrical measurements, it was shown that antenna performances were in good agreement with design requirements. In cyclic 4-point bending, flexure behavior was investigated by static and fatigue test. Fatigue life curve of SAS was obtained. The fatigue load was determined experimentally at a 0.75 (1.875kN) load level, Experimental results were compared with single load level fatigue life prediction equations (SFLPE) and in good agreement with SFLPE. SAS concept is the first serious attempt at integration fur both antenna and composite engineers and promises innovative future communication technology.

• Steel and Composite Structures
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• v.43 no.5
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• pp.581-601
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• 2022

The main objective of this research work is to investigate the free vibration behavior of annular sandwich plates resting on the Kerr foundation at thermal conditions. This sandwich configuration is composed of two FGM face sheets as coating layer and a porous GPLRC (GPL reinforced composite) core. It is supposed that the GPL nanofillers and the porosity coefficient vary continuously along the core thickness direction. To model closed-cell FG porous material reinforced with GPLs, Halpin-Tsai micromechanical modeling in conjunction with Gaussian-Random field scheme is used, while the Poisson's ratio and density are computed by the rule of mixtures. Besides, the material properties of two FGM face sheets change continuously through the thickness according to the power-law distribution. To capture fundamental frequencies of the annular sandwich plate resting on the Kerr foundation in a thermal environment, the analysis procedure is with the aid of Reddy's shear-deformation plate theory based high-order shear deformation plate theory (HSDT) to derive and solve the equations of motion and boundary conditions. The governing equations together with related boundary conditions are discretized using the generalized differential quadrature (GDQ) method in the spatial domain. Numerical results are compared with those published in the literature to examine the accuracy and validity of the present approach. A parametric solution for temperature variation across the thickness of the sandwich plate is employed taking into account the thermal conductivity, the inhomogeneity parameter, and the sandwich schemes. The numerical results indicate the influence of volume fraction index, GPLs volume fraction, porosity coefficient, three independent coefficients of Kerr elastic foundation, and temperature difference on the free vibration behavior of annular sandwich plate. This study provides essential information to engineers seeking innovative ways to promote composite structures in a practical way.

• Computers and Concrete
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• v.34 no.4
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• pp.447-476
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• 2024

The current research proposes an innovative finite element model established within the context of higher-order beam theory to examine the bending and buckling behaviors of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beams resting on Winkler-Pasternak elastic foundations. This two-node beam element includes four degrees of freedom per node and achieves inter-element continuity with both C¹ and C⁰ continuities for kinematic variables. The isoparametric coordinate system is implemented to generate the elementary stiffness and geometric matrices as a way to enhance the existing model formulation. The weak variational equilibrium equations are derived from the principle of virtual work. The mechanical properties of FG-CNTRC beams are considered to vary gradually and smoothly over the beam thickness. The current investigation highlights the influence of porosity dispersions through the beam cross-section, which is frequently omitted in previous studies. For this reason, this analysis offers an enhanced comprehension of the mechanical behavior of FG-CNTRC beams under various boundary conditions. Through the comparison of the current results with those published previously, the proposed finite element model demonstrates a high rate of efficiency and accuracy. The estimated results not only refine the precision in the mechanical analysis of FG-CNTRC beams but also offer a comprehensive conceptual model for analyzing the performance of porous composite structures. Moreover, the current results are crucial in various sectors that depend on structural integrity in specific environments.

• 한국벤처창업학회:학술대회논문집
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• 2017.08a
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• pp.1-13
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• 2017

In the era of the 4th Industrial Revolution, as the importance of creative talent became more and more important, we recognized the urgent need for start-ups to innovate new growth industries and creative talents to lead these eras.And the importance of entrepreneurship education emphasized in entrepreneurship education and the necessity of creativity competency education.However, there is a lack of research on how creativity competency education affects entrepreneurship intention for college students. Especially, research on the moderating effect of social support on the effect of entrepreneurship through education is very insufficient. The purpose of this study is to examine the effects of creativity competence education on the will of entrepreneurship and empowerment of social support. For this purpose, 393 college students were used for empirical analysis for 1 month from August 2016. As a result of this study, the ability of communicative communication and creative problem solving had a positive effect on self - efficacy. On the other hand, innovative work behavior abilities did not directly affect self-efficacy. In addition, creative problem solving ability and innovative work behavior ability had a positive effect on the will to start up. Collaborative communication skills, however, did not directly affect the willingness to start a business. Self - efficacy has a positive effect on the will of founding. Finally, the moderating effect of social support between self-efficacy and willingness to work was not directly affected. The implication of this study is that the effect of the creativity competency education on college students has a positive effect on the self - efficacy of self and the positive influence on the will to start up. The results of this study are as follows. First, it is found that the influence of social support (parental support) is not positively influenced by the control effect of the parents. In the case of college students, As well as the need to do so. Therefore, in order to further increase the willingness of young people to establish a university in the university, it is necessary to provide education and programs not only for direct education for college students, but also for improving the understanding of the talents and entrepreneurship required by the age of their parents.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.161-170
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• 2017

Research should explore techniques that will allow disposal of the dead to help the living by providing public space, protecting the environment, and contributing to economic development. Its design might bring a cemetery back into community life and make a present of a park. This new design for a cemetery can provide a structural solution for limited burial sites on the metropolitan area of Korea. It is based on the shared sense of a cemetery, a joint ownership or co-ownership of the space of a cemetery. FBS model by Gero[1] is used for engineering a cemetery design development. This framework contains a dynamic character of the context where such design takes place among its function, behavior and structure. This study suggests a new cemetery concept rather than a simple civil engineering work for a cemetery. It aims for people to have a new perspective on a cemetery and contribute to the society through an eco-friendly business model, so FBS may be an adequate model for such design. It can be one of the innovative business models and designs for engineering cemeteries, implementing sustainable environment and changing the design from a cemetery to a natural park.