• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.460-469
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• 2000

A study on the corrosion behavior of RE36 steel for marine structure was investigated with parameters such as micro-Vickers hardness, corrosion potential and corrosion current density measurement of weld metal(WM), base metal (BM) and heat affected zone(HAZ), Al anode generating current and Al anode weight loss quantity in case of cathodic protection. And we carried out slow strain rate test(SSRT) in order to research mechanical properties such as stress at maximum load, percent strain, time to fracture and strain to failure ratio etc and to find out limiting cathodic polarization potential for hydrogen embrittlement with applied cathodic polarization potential. Hardness of HAZ part was the highest among those three parts and also galvanic corrosion susceptibility was the highest in HAZ part among those three parts due to the lowest corrosion potential than other parts. However corrosion current density was the highest in WM part among those three parts. And the optimum cathodic polarization potential showing the best mechanical properties obtained by SSRT method with applied constant cathodic potential was from - 770mV to - 875mV(SCE). However it is suggested that limiting cathodic polarization potential indicating hydrogen embrittlement on the mechanical properties was under - 900mV(SCE).

• Steel and Composite Structures
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• v.11 no.4
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• pp.273-290
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• 2011

In current ductility-based earthquake-resistant design, the estimation of design forces continues to be carried out with the application of response modification factors on elastic design spectra. It is well-known that the response modification factor (R) takes into account the force reduction, strength, redundancy, and damping of structural systems. The key components of the response modification factor (R) are force reduction ($R_{\mu}$) and strength ($R_S$) factors. However, the response modification and strength factors for structural systems presented in design codes were based on professional judgment and experiences. A numerical study has been accomplished to evaluate force reduction, strength, and response modification factors for special steel moment resisting frames. A total of 72 prototype steel frames were designed based on the recommendations given in the AISC Seismic Provisions and UBC Codes. Number of stories, soil profiles, seismic zone factors, framing systems, and failure mechanisms were considered as the design parameters that influence the response. The effects of the design parameters on force reduction ($R_{\mu}$), strength ($R_S$), and response modification (R) factors were studied. Based on the analysis results, these factors for special steel moment resisting frames are evaluated.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.2
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• pp.27-33
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• 2011

This study is a preliminary investigation into the development of a construction method that will protect a reservoir even during over flows caused by severe flooding. Through hydraulic modeling tests, the destructive phenomena caused by spillway-junction scour during reservoir overflow were modeled, and the effects on the embankment during such an overflow and the spillway-junction movements are discussed. The reservoir destruction model used the Tanbu reservoir, located in Gangwondo Chuncheon-si Namsanmyeon (H＝22 m, L＝115 m), as the model reservoir and created an embankment with a 1/60 ratio. We review the spillway-junction safety factor during overflow and embankment movement following reinforcement measures for three different cases: no reinforcement, cemented sand and gravel (CSG) reinforcement and water-blocking sheet reinforcement. The results of this study confirmed that when the spillway-junction is exposed to soil, it is very vulnerable to overflow and that a water-blocking sheet or CSG reinforcement are very effective measures in preventing embankment destruction in the long-term period.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.2
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• pp.195-201
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• 1998

The purpose of this study is to evaluate the flexural strengthening effects of RC beams reinforced with carbon fiber sheets (CFS) in variable of strengthening amount and anchorage length of CFS. This study can be summarized as follows ; The CFS shares the tensile stress such as rebar during loading test. Also, as the strengthening amount of CFS is increased, the maximum flexural strength of RC beams reinforced with CFS is increased. Therefore, it is confirmed that the CFS's strengthening method is very effective to improve the flexural strength of RC beams. The maximum flexural strength of RC beams with CFS is determined by bond failure between CFS and concrete surface. So, the evaluation of CFS's strengthening effect can be calculated using the tensile stress of CFS which is peeling. When the anchorage length of CFS is increased, the ductility of RC beams is increased because of delaying the peeling of CFS. But, in case of same anchorage length of CFS, when the strengthening amount of CFS is increased, the ductility is decreased. Therefore, it is considered that the anchorage of CFS in the end zone is necessary.

• Journal of Korea Port Economic Association
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• v.18 no.2
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• pp.109-133
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• 2002

The China entered World Trade Oganization(WTO) last year, thus opening its border to more - and freer - trade. With its foreign trade rapidly expanding and with economic growth continuing at a substantial -rate, China will be the largest container traffic generating country in the world. In the light of this potential trade bonanza, regional ports in North-East Asia strive to gain a competitive-edge. The Port of Busan, the world's third largest container port, wants to capture a significant share of the china's container cargoes. In this circumstance, development strategies of the Port of Busan are suggested as follows. First, to cope with increasing volumes, the New Busan Port on Gaduk island should be constructed without failure. Second, it is necessary to add modernized high-performance gantry cranes and to train crane operators' skill. Third, it needs to apply Dwell Time- Sliding Scale System for transshipment cargoes. Fourth, it needs to develop the EDI network in terminal areas or adjacent hub ports to exchange trustworthy and satisfactory informations Fifth, port authority -needs to enlarge designated Free Trade Zone to facilitate the free flow of cargoes. Sixth, the restoration of rail links between North and South Korea is abundantly clear. Thus it needs to enlarge railroad facilities in advance. Seventh, it needs to establish the Port Authority of Busan immediately. Finally, it needs to strengthen port sales and to open events like 'Marine Week 2001' regularly to attract potential canters or big shippers.

• Structural Engineering and Mechanics
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• v.56 no.2
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• pp.275-291
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• 2015

Adherence between reinforcement and the surrounding concrete is usually ignored in finite element analysis (FEA) of reinforced concrete (RC) members. However, load transition between the reinforcement and surrounding concrete effects RC members' behavior a great deal. In this study, the effects of bond-slip on the FEA of RC members are examined. In the analyses, three types of bond-slip modeling methods (perfect bond, contact elements and spring elements) and three types of reinforcement modeling methods (smeared, one dimensional line and three dimensional solid elements) were used. Bond-slip behavior between the reinforcement and surrounding concrete was simulated with cohesive zone materials (CZM) for the first time. The bond-slip relationship was identified experimentally using a beam bending test as suggested by RILEM. The results obtained from FEA were compared with the results of four RC beams that were tested experimentally. Results showed that, in FE analyses, because of the perfect bond occurrence between the reinforcement and surrounding concrete, unrealistic strains occurred in the longitudinal reinforcement. This situation greatly affected the load deflection relationship because the longitudinal reinforcements dominated the failure mode. In addition to the spring elements, the combination of a bonded contact option with CZM also gave closer results to the experimental models. However, modeling of the bond-slip relationship with a contact element was quite difficult and time consuming. Therefore bond-slip modeling is more suitable with spring elements.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.4
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• pp.439-455
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• 2020

Numerical model was developed that simulates radionuclide (3H and 14C) transport modeling at the 2nd phase facility at the Wolsong LILW Disposal Center. Four scenarios were simulated with different assumptions about the integrity of the components of the barrier system. For the design case, the multi-barrier system was shown to be effective in diverting infiltration water around the vaults containing radioactive waste. Nevertheless, the volatile radionuclide 14C migrates outside the containment system and through the unsaturated zone, driven by gas diffusion. 3H is largely contained within the vaults where it decays, with small amounts being flushed out in the liquid state. Various scenarios were examined in which the integrity of the cover barrier system or that of the concrete were compromised. In the absence of any engineered barriers, 3H is washed out to the water table within the first 20 years. The release of 14C by gas diffusion is suppressed if percolation fluxes through the facility are high after a cover failure. However, the high fluxes lead to advective transport of 14C dissolved in the liquid state. The concrete container is an effective barrier, with approximately the same effectiveness as the cover.

• Steel and Composite Structures
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• v.47 no.3
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• pp.375-382
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• 2023

The H-shaped steel beam is popular due to its ease of manufacturing and connection to the column. This profile, which is used as a shallow beam, needs the high weak-axis bending stiffness and torsional stiffness to meet the overall stability. Achieving the local beam flange stability, bearing capacity, bending stiffness, and torsional requirements need a great thickness and width of the beam flange, which causes, which will cause more uneconomical structural design. So, the box-section beam is the ideal alternative. However, the current design specifications do not have design rules for the bolt-and-welded connection of the box-section beam and box-section column. The paper proposes a novel bolt-and-welded connection of the box-section beams and box-section columns based on a high-rise structural design scheme. Three connection models, BASE, WBF, and RBS, are analyzed under cyclic loading in ABAQUS software. The failure modes, hysteresis response, bearing capacity, ductility, plastic rotation angle, energy dissipation, and stiffness degradation of all models are determined and compared. Compared with the other two models, the model WBF exhibited excellent seismic performance, ductility, and plastic rotation ability. Finally, model WBF was chosen as the connection scheme used in the project design.

• Geomechanics and Engineering
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• v.32 no.4
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• pp.361-373
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• 2023

This study aimed to investigate the engineering properties and mechanical behaviors of polymer-fibers treated sand. Para rubber (PR), natural fiber (NF), and geosynthetic fiber (GF) were used to reinforce poorly graded sand. A series of unconfined compressive and splitting tensile strength tests were performed to analyze the engineering behaviors and strength enhancement mechanism. The experiment results indicated that the PR-fibers mixture could firmly enhance the strength properties of sand. The stress-strain characteristics and failure patterns have been changed due to the increase of PR and fibers content. The presence of PR and fibers strengthened the sand and enhanced the stiffness and ductility behavior of the mixture. The stiffness of reinforced sand reaches an optimum state when both NF and GF are 0.5%, while the optimum PR contents are 20% and 22.5% for the mixture with NF and GF, respectively. An addition of PR and fiber into sand contributed to increasing interlocking zone and bonding of PR-sand interfacial.

• Advances in Computational Design
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• v.7 no.4
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• pp.281-295
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• 2022

Tensile property is one of the excellent properties of ultra-high performance concrete (UHPC), and uniaxial tensile test is an important and challenging mechanical performance test of UHPC. Traditional uniaxial tensile tests of concrete materials have inherent defects such as initial eccentricity, which often lead to cracks and failure in non-test zone, and affect the testing accuracy of tensile properties of materials. In this paper, an original integrated design scheme of mould and end fixture is proposed, which achieves seamless matching between the tension end of specimen and the test fixture, and minimizes the cumulative eccentricity caused by the difference in the matching between the tension end of specimen and the local stress concentration at the end. The stress analysis and optimization design are carried out by finite element method. The curve transition in the end of specimen is preferred compared to straight line transition. The rationality of the new integrated design is verified by uniaxial tensile test of strain hardening UHPC, in which the whole stress-strain curve was measured, including the elastic behavior before cracking,strain hardening behavior after cracking and strain softening behavior.