• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.592-602
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• 2021

Thorium compounds have attracted immense scientific and technological attention with regard to both fundamental and practical implications, owing to unique chemical and physical properties like high melting point, high density and thermal conductivity. Hereby, we investigate the mechanical and thermodynamic stability and report on the structural, electronic and magnetic properties of new silicon-doped cubic ternary thorium phosphides ThSi_xP_1-x (x = 0, 0.25, 0.5, 0.75 and 1). The first-principles density functional theory procedure was adopted within full-potential linearized augmented plane wave (FP-LAPW) method. The exchange and correlation potential terms were treated within Generalized-Gradient-Approximation functional modified by Perdew-Burke-Ernzerrhof parameterizations. The proposed compounds showed mechanical and thermodynamic stable structure and hence can be synthesized experimentally. The calculated lattice parameters, bulk modulus, total energy, density of states, electronic band structure and spin magnetic moments of the compounds revealed considerable correlation to the Si substitution for P and the relative Si/P doping concentration. The electronic and magnetic properties of the doped compounds rendered them non-magnetic but metallic in nature. The main orbital contribution to the Fermi level arises from the hybridization of Th(6d+5f) and (Si+P)3p states. Reported results may have potential implications with regard to both fundamental point of view and technological prospects such as fuel materials for clean nuclear energy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.632-638
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• 2019

This paper presents the conceptual design and reaction force analysis of a bogie structure for an inter-modal automated transportation system, including road and rail transportation. The proposed system was based on a train with rotation-aligning bogie mechanism that can save significant time and cost. One of the critical issues in conceptual design is the lateral forces applied to the rail caused by the characteristic shapes and structure of the rails and bogie. In particular, the lateral forces are significant in the transition section between the driving and platform sections. This paper provides design guidance for the transition section through reaction force analysis. Based on the analysis result, it was confirmed that the proposed concept can be a valid design candidate of a practical system, and the radius of the rail and the distance between rails are major factors for reaction force generation.

• International journal of steel structures
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• v.18 no.5
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• pp.1617-1630
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• 2018

The crucial differences between conventional rail with split-type connectors and continuous welded rails are axial stress in the longitudinal direction and stability, as well as other issues generated under the influence of loading effects. Longitudinal stresses generated in continuously welded rails on railway bridges are strongly influenced by the nonlinear behavior of the supporting system comprising sleepers and ballasts. Thus, the track structure interaction cannot be neglected. The rail-support system mentioned above has properties of non-uniform material distribution and uncertainty of construction quality. The linear elastic hypothesis therefore cannot correctly evaluate the stress distribution within the rails. The aim of this study is to apply the nonlinear finite element method using the nonlinear coupling interface between the track and structural model and to illustrate the welded rail behavior under the loading effect and uncertain factors of the ballast. Numerical results of nonlinear finite analysis with a three-dimensional solid and frame element model are presented for a typical track-bridge system. A composite plate girder, modeled by solid and shell elements, is also analyzed to consider the behavior of the welded rail. The analysis result showed buckling under the independent calculations of load cases, including 'temperature change', 'bending of the supporting structure', and 'braking' of the railway vehicle. A parametric study of the load combination method and the loading sequence is also included in this analysis.

• Journal of the Korean Institute of Rural Architecture
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• v.24 no.2
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• pp.21-28
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• 2022

Focusing on the creation of a new han ok, especially a mid-rise hybrid-structured Han-ok, this study proposes a middle-rise (four-story) Han-ok on one and two lots located in Seoun-dong, the existing Han-ok intensive housing site in downtown Cheongju. 1) In terms of layout and function, according to the existing L-shaped Han-ok corresponding to the road and the direction, the parking lots and shops on the 1st floor, the business facility on the 2nd floor, the Han-ok on the 3rd and 4th floors are placed. There are yards, open roof yards, and semi-open Daecheong(大廳, main hall), which can be shared by residents. 2) In terms of structure and form, one or two floors (some 3 floors) are 5.4m square and 5.4×6.6m modules of the RC(Reinforced Concrete) group, and the upper floor reflects the 2.7m module, size and shape of the existing Han-ok. By extending the outer wall of the RC group in the lower floors (1st to 3rd floors) to the wooden exterior of the upper floors (2nd to 4th floors), it is attempted to avoid the awkward appearance of the RC group being exposed to wooden structures. And it is also attempted to reflect the wooden shape and design elements through the elevation elements such as horizontal windows, corner windows, picture frames, and vertical slits. 3) In environmental control and facilities, it is attempted to smooth the ventilation of the building by forming a vertical upward airflow from the dark space of the low floor to the positive of the upper floor. This doubles the effect through a vertical rise of cold air generated in a narrow alleyway, piloti parking lot, and the various voids. In addition to the Daecheong and Numaru(loft) of Han ok, the rooftop yard, the terrace, and the balcony, horizontal natural ventilation is generated through divided doors and transom windows.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3D
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• pp.331-338
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• 2008

Road pavements consist of layered structure and each layer is made of various materials. The load responses of pavement structures are very sensitive to properties of subbase materials. Successful pavement design, therefore, depends on the method and the accuracy of measuring material properties, and it requires realistic description of the behavior of layered materials. Resilient modulus ($M_R$) is widely used properties representing pavement structure materials. In this study, we collected data for mechanical characteristics of subbase materials that were used in domestic construction and adopted them to form a constitutive equation of subbase $M_R$ value. Proposed model was evaluated through the finite element analysis.

• Smart Structures and Systems
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• v.32 no.3
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• pp.153-166
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• 2023

Health monitoring of civil infrastructures, in particular, old bridges that are still in service, has become more than necessary, given the risk that a possible degradation or failure of these infrastructures can induce on the safety of users in addition to the resulting commercial and economic impact. Bridge integrity assessment has attracted significant research efforts over the past forty years with the aim of developing new damage identification methods applicable to real structures. The bridge of Ouled Mimoun (Tlemcen, Algeria) is one of the oldest railway structure in the country. It was built in 1889. This bridge, which is too low with respect to the level of the road, has suffered multiple shocks from various machines that caused considerable damage to its central part. The present work aims to analyze the stability of this bridge by identifying damages and evaluating the damage rate in different parts of the structure on the basis of a finite element model. The applied method is based on an inverse analysis of the normal stress responses that were calculated from the corresponding recorded strains, during the passage of a real train, by means of a set of strain gauges placed on certain elements of the bridge. The results obtained from the inverse analysis made it possible to successfully locate areas that were really damaged and to estimate the damage rate. These results were also used to detect an excessive rigidity in certain elements due to the presence of plates, which were neglected in the numerical reference model. In the case of the continuous bridge monitoring, this developed method will be a very powerful tool as a smart health monitoring system, allowing engineers to take in time decisions in the event of bridge damage.

• International Journal of Highway Engineering
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• v.10 no.1
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• pp.63-74
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• 2008

Resilient deformation characteristics on unbound pavement materials have been adopted for design and nonlinear analysis of pavement structure under traffic loadings. However, relatively few studies have been done on the nonlinear resilient behavior of unbound pavement materials in Korea. In addition, only the limited information is available for estimating the resilient modulus values on unbound materials. In this study, a laboratory resilient-deformation test under repeated loadings is performed in order to fud a proper constitutive model that correlates the resilient modulus with stress state from field condition. Finally, a finite element analysis is conducted for evaluating the nonlinear characteristics of unbound materials. and the pavement performance respectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.31-37
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• 2008

In order to organize the Intelligent Transport System(ITS) as a communication equipment, the satellite and wireless system demand broadband characteristics for collecting information from the wide road. Band-pass filters (BPF) or broad BPFs used in such communication system are required for broadband characteristics. This paper presents a design of such broad BPF which can be used in the system. Designed BPF which was difficult to get broadband characteristics after realization, become possible to realize filter with broad bandwidth and compact structure using parallel coupled line. The designed filter achieved the insertion losses improved by 0.4 dB and the return losses improved by 17.4 dB respectively with 60% of bandwidth at the 5.8 GHz of the center frequency, respectively.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1739-1742
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• 2011

Public transportation network in our country is concentrated and advanced focusing on urban area in order to secure economic feasibility. As a result, as dependence on private vehicles is relatively getting higher in public transportation vulnerable area, traffic problem occurs since the average running speed in urban area is 22.5km/h. This paper has an objective to suggest an improvement plan by selecting public transportation vulnerable area, and defining according to urban structure, formation and function, and understand traffic characteristics and draw problems. As a method selecting public transportation vulnerable area, an area with high division rate of vehicle was selected as a primary proposed site by calculating division rate of means of public transportation according to area. Final proposed site was selected by using GIS Buffering technique aiming at selected proposed site, and selecting non-benefit area 500m outside, which is the road limit distance from each subway and bus station. Lastly, the degree of improvement effect was studied by constructing imaginary public transportation network aiming at final proposed site and comparing to the amount of change in division rate of means of transportation.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2393-2399
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• 2011

In the case where the bottom of railroad is penetrated by non-excavation construction method, the design is performed based on the assumption that there is no displacement and no change of stress However, measurement data showed that reduction of earth pressure and relaxation of stress take place by the displacement. In this study, we investigated the earth pressure on the structure under the railroad constructed by a non-excavation method and the stress relaxation region. The design based on earth pressure is non-economical because it is an over design. Relaxation of stress may lead to road base settlement and rail irregularly due to the reduced railroad supporting stiffness, to ballast crack in the case of concrete roadbed. The result showed that it is reasonable to set the stress on the structures as active earth pressure not as earth pressure at rest. Additionally, the study on the stress relaxation region identified the regions that should be supported in future construction by a non-excavation method.