• Animal Bioscience
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• 제37권2호
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• pp.193-202
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• 2024

Objective: Oxidative stress (OS) is a pathological process arising from the excessive production of free radicals in the body. It has the potential to alter animal gene expression and cause damage to the jejunum. However, there have been few reports of changes in the expression of long noncoding RNAs (lncRNAs) in the jejunum in piglets under OS. The purpose of this research was to examine how lncRNAs in piglet jejunum change under OS. Methods: The abdominal cavities of piglets were injected with diquat (DQ) to produce OS. Raw reads were downloaded from the SRA database. RNA-seq was utilized to study the expression of lncRNAs in piglets under OS. Additionally, six randomly selected lncRNAs were verified using quantitative real-time polymerase chain reaction (qRT-PCR) to examine the mechanism of oxidative damage. Results: A total of 79 lncRNAs were differentially expressed (DE) in the treatment group compared to the negative control group. The target genes of DE lncRNAs were enriched in gene ontology (GO) terms and Kyoto encyclopedia of genes and genomes (KEGG) signaling pathways. Chemical carcinogenesis-reactive oxygen species, the Foxo signaling pathway, colorectal cancer, and the AMPK signaling pathway were all linked to OS. Conclusion: Our results demonstrated that DQ-induced OS causes differential expression of lncRNAs, laying the groundwork for future research into the processes involved in the jejunum's response to OS.

• 한국건설관리학회논문집
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• 제10권2호
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• pp.84-92
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• 2009

최근 가변성능에 관하여 공간, 재료, 구조, 공법 등 건설 산업 전반에 걸쳐 많은 연구가 진행 중이며, 이와 더불어 공동주택의 노후화 문제로 인하여 건축요소기술의 개발이 가속화되고 있다. 이에 따라 본 연구에서는 최근 사회적으로 부각되고 있는 가변성능에 관한 공동주택의 요소기술 선정 및 대상사례를 중심으로 한 설문조사와 전문가 의견을 거쳐 건축요소기술의 평가항목을 1차적으로 선정하고자 한다. 그리고 선정된 건축요소기술 항목 중에서 타당성 및 객관성 검증절차를 통하여 건축요소기술을 재정립 및 분류하고, 최종적으로 적용 가능한 다양한 건축요소기술 가운데 우선순위가 높은 항목들을 결정하여 분석 및 평가함으로써 향후 장수명 공동주택의 가변성능향상을 위한 지침을 제시하고자 한다.

• Steel and Composite Structures
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• 제49권5호
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• pp.517-532
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• 2023

Tower structures have been widely used in communication and transmission engineering. The failure of joints is the leading cause of structure failure, which make it play a crucial role in tower structure engineering. In this study, the aluminum alloy three tube tower structure is taken as the prototype, and the middle joint of the tower was selected as the research object. Three different stainless steel-aluminum alloy composite joints (SACJs), denoted by TA, TB and TC, were designed. Finite element (FE) modeling analysis was used to compare and determine the TC joint as the best solution. Detail requirements of fasteners in the TC stainless steel-aluminum alloy composite joint (TC-SACJ) were designed and verified. In order to systematically and comprehensively study the mechanical properties of TC-SACJ under multi-directional loading conditions, the full-scale experiments and FE simulation models were all performed for mechanical response analysis. The failure modes, load-carrying capacities, and axial load versus displacement/stain testing curves of all full-scale specimens under tension/compression loading conditions were obtained. The results show that the maximum vertical displacement of aluminum alloy tube is 26.9mm, and the maximum lateral displacement of TC-SACJs is 1.0 mm. In general, the TC-SACJs are in an elastic state under the design load, which meet the design requirements and has a good safety reserve. This work can provide references for the design and engineering application of aluminum alloy tower structures.

• 한국도로학회논문집
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• 제16권3호
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• pp.9-20
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• 2014

PURPOSES : This study is to compare load transfer efficiency of key joint and dowel joint for airport concrete pavement. METHODS : As AC150/5320-6D of FAA's [Advisory Circular] was changed into AC150/5320-6E, Key joint type of rigid pavement were excluded from Construction Joints. LTE(Load Transfer Efficiency) of dowel joint and key joint were compared by times and seasons through pavement temperature measurement, ocular investigation and HWD measurement. RESULTS : For the joint performance grade of No. 2(The second) runway of airport, 12% of poor rate was observed in key joint and 2% of poor rate in dowel joint. Poor rate of key joint was increased to 17%, if only No. 3~No. 6 slabs, which are mostly loaded from the airplanes, were applied for the study. In apron area, LTE poor rate of key joint was high in winter, and LTE poor rate of dowel joint was at least above 'Fair' grade. In summer, 'Fair' for key joint, 'Acceptable' for dowel joint appeared. CONCLUSIONS : As results, dowel joint was superior than key joint for LTE. Deviations of seasons and times were smaller in dowel joint's result. And LTE in winter was lower than LTE in summer.

• Geomechanics and Engineering
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• 제37권1호
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• pp.9-19
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• 2024

This study presents an energy analysis for large-strain cavity expansion problem based on the general strength criterion and energy theory. This study focuses on the energy dissipation problem during the cavity expansion process, dividing the soil mass around the cavity into an elastic region and a plastic region. Assuming compliance with the small deformation theory in the elastic region and the large deformation theory in the plastic region, combined with the general strength criterion of soil mass and energy theory, the energy dissipation solution for cavity expansion problem is derived. Firstly, from an energy perspective, the process of cavity expansion in soil mass is described as an energy conversion process. The energy dissipation mechanism is introduced into the traditional analysis of cavity expansion, and a general analytical solution for cavity expansion related to energy is derived. Subsequently, based on this general analytical solution of cavity expansion, the influence of different strength criterion, large-strain, expansion radius, cavity shape and characteristics of soil mass on the stress distribution, displacement field and energy evolution around the cavity is studied. Finally, the effectiveness and reliability of theoretical solution is verified by comparing the results of typical pressure-expansion curves with existing literature algorithms. The results indicate that different strength criterion have a relatively small impact on the displacement and strain field around the cavity, but a significant impact on the stress distribution and energy evolution around the cavity.

• Geomechanics and Engineering
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• 제35권4호
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• pp.395-409
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• 2023

Long-span suspension bridges have tunnel anchor systems to maintain stable cables. More investigations are required to determine how closely tunnel excavation beneath the tunnel anchor impacts the stability of the tunnel anchor. In order to investigate the impact of the adjacent tunnel's excavation on the stability of the tunnel anchor, a large-span suspension bridge tunnel anchor is utilised as an example in a three-dimensional numerical simulation approach. In order to explore the deformation control mechanism, orthogonal tests are employed to pinpoint the major impacting elements. The construction of an advanced pipe shed, strengthening the primary support. Moreover, according to the findings the grouting reinforcement of the surrounding rock, have a significant control effect on the settlement of the tunnel vault and plug body. However, reducing the lag distance of the secondary lining does not have such big influence. The greatest way to control tunnel vault settling is to use the grout reinforcement, which increases the bearing capacity and strength of the surrounding rock. This greatly minimizes the size of the tunnel excavation disturbance area. Advanced pipe shed can not only increase the surrounding rock's bearing capacity at the pipe shed, but can also prevent the tunnel vault from connecting with the disturbance area at the bottom of the anchorage tunnel, reduce the range of shear failure area outside the anchorage tunnel, and have the best impact on the plug body's settlement control.

• Geomechanics and Engineering
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• 제34권3호
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• pp.303-316
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• 2023

With the development and utilization of urban underground space, the artificial ground freezing technology has been widely used in the construction of underground engineering in soft soil areas. The mechanical properties of soft clay changed greatly after freezing and thawing, which affected the seismic performance of underground structures. In this paper, a series of triaxial tests were carried out to study the dynamic response of the freezing-thawing clay under the seismic load considering different dynamic stress amplitudes and different confining pressures. The reduction factor of dynamic shear stress was determined to correct the amplitude of the seismic load. The deformation development mode, the stress-strain relationship and the energy dissipation behavior of the soft clay under the seismic load were analyzed. An empirical model for predicting accumulative plastic strain was proposed and validated considering the loading times, the confining pressures and the dynamic stress amplitudes. The relevant research results can provide a theoretical reference to the seismic design of underground structures in soft clay areas.

• Geomechanics and Engineering
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• 제27권6호
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• pp.561-571
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• 2021

Cofferdams made of teel sheet piles are commonly utilized as support structures for excavation of sea-crossing bridge foundations. As cofferdams are often subject to tide variation, it is imperative to consider potential effects of tide on stability and serviceability of sheet piles, particularly, ultralong steel sheet piles (USSPs). In this study, a real USSP cofferdam constructed using new construction technology in Nanxi River was reported. The design of key parts of USSP cofferdam in the presence of tidal action was first introduced followed by the description of entire construction technology and associated monitoring results. Subsequently, a three-dimensional finite-element model corresponding to all construction steps was established to back-analyze measured deflection of USSPs. Finally, a series of parametric studies was carried out to investigate effects of tide level, soil parameters, support stiffness and construction sequence on lateral deflection of USSPs. Monitoring results indicate that the maximum deflection during construction occurred near the riverbed. In addition, measured stress of USSPs showed that stability of USSP cofferdam strengthened as construction stages proceeded. Moreover, the numerical back-analysis demonstrated that the USSP cofferdam fulfilled the safety requirements for construction under tidal action. The maximum deflection of USSPs subject to high tide was only 13.57 mm at a depth of -4 m. Sensitivity analyses results showed that the design of USSP cofferdam system must be further improved for construction in cohesionless soils. Furthermore, the 5th strut level before concreting played an indispensable role in controlling lateral deflection of USSPs. It was also observed that pumping out water before concreting base slab could greatly simplify and benefit construction program. On the other hand, the simplification in construction procedures could induce seepage inside the cofferdam, which additionally increased the deflection of USSPs by 10 mm on average.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.14-20
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• 2013

Substantial research has been performed on the data standards and exchanges in the AEC/FM industry over the past several years. The growing popularity of BIM technology is based heavily upon a perception that the technology can facilitate the sharing and reuse of information during a project life-cycle. Although many researchers and practitioners are in agreement about the potential applicability and benefit of BIM in construction, it is still unclear why BIM is adopted, and what factors enhance implementation of BIM. Thus, BIM acceptance and use remains a central concern of BIM research and practice. Therefore, we propose the key factors affecting the acceptance of BIM in construction organizations using factor analysis. The key factors for BIM acceptance are identified through a literature review in TAM (Davis 1989) and related theories, and consolidated by interviews and pilot studies with professionals in construction industry. Based on the factors, a questionnaire was designed and sent out to construction organizations such as contractors, architects, and engineers in Korea. Total 148 completed questionnaires were retrieved. Using factor analysis, key factors were grouped into six dimensions. These findings will clarify what the highly prioritized factors are, and can also be used in an assessment tool for the performance of BIM utilization.

• Structural Engineering and Mechanics
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• 제71권2호
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• pp.109-118
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• 2019

This paper presents the numerical simulation of membrane structure under impact load. Firstly, the numerical simulation model is validated by comparing with the test in Hao's research. Then, the effects of the shape of the projectile, the membrane prestress and the initial impact speed, are investigated for studying the dynamic response and failure mechanism, based on the membrane displacement, projectile acceleration and kinetic energy. Finally, the results show that the initial speed and the punch shape are related with the loss of kinetic energy of projectiles. Meanwhile, the membrane prestress is an important factor that affects the energy dissipation capacity and the impact resistance of membrane structures.