• Geomechanics and Engineering
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• v.31 no.2
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• pp.197-208
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• 2022

Micropiles consisting of steel bars and grouts are commonly used in underpinning methods to reinforce supports or to suppress the subsidence of existing structures. Recently, applications in the field of geotechnical engineering have expanded. Despite the increasing use of micropiles are used, the PHC or steel pile formula is still applied for the settlement amount of micropiles. Compared with field test results, the amount of micropile subsidence obtained from the existing method may result in a very large error in the displacement of the micropile. Therefore, it is difficult to utilize micropiles effectively. Hence, to solve this problem, this study evaluated the behaviors and support characteristics of micropiles through field compression and tensile tests, and proposed a method for predicting the amounts of their subsidence. To confirm the appropriateness of the proposed method, field test results and the results obtained using the proposed method were compared. It was found that the settlement amounts of the micropiles as predicted through the existing method were significantly overestimated (error ≈ 50-80%) relative to the field test results, whereas the settlement errors of the piles predicted through the proposed method decreased (error ≈6-32%). Thus, it is possible to reduce the previously overestimated amount of settlement, and the modified method of this study allows more efficient design than the conventional method.

• Journal of Korean Association for Spatial Structures
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• v.24 no.3
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• pp.87-93
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• 2024

Recently, the floor construction method of buildings is rapidly being replaced by the steel deck construction method of factory products from the past cast-in-place formwork method in order to shorten construction period, reduce labor costs, and improve constructability. In this study, the bending capacity of a newly developed lattice integrated rib-type deck plate that is economical and constructible was evaluated through a simple beam test. As a result of the experiment, the lattice integrated rib-type deck installed by adding rib to the existing flat deck had excellent initial rigidity and maximum load-bearing ability, confirming the feasibility of practical use. In addition, the test specimen in which the tensile rebar is not integrated with the lattice and deck has very low initial stiffness, which is insufficient to support the load at the construction stage, and new details need to be developed to overcome this.

• Journal of Korean Foot and Ankle Society
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• v.14 no.2
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• pp.177-181
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• 2010

Purpose: The author evaluated the clinical and radiological results after wearing the medial arch supports in children. Materials and Methods: 103 patients who had symptomatic flat feet were evaluated from march, 2002 to may 2009. All patients wore the medial arch supports according to the symptoms. We measured parameters at weight-bearing radiographs before and after medial arch support were worn. We also evaluated the clinical scores using the AOFAS score. Results: Mean age of patients was 97 months (11-204 months), all foot of patients involved bilaterally. Mean talo-first metatarsal angle of right foot was $17.7{\pm}9.4$ and left foot was $19.96{\pm}9.5$ degrees at AP radiograph in pre-wearing state. Mean calcaneal pitch angle of right foot was $12.0{\pm}5.3$ and left foot was $11.9{\pm}5.8$ degrees at lateral radiograph in pre-wearing state. Mean talo-first metatarsal angle of right foot was $14.4{\pm}8.05$ and left foot was $13.1{\pm}8.77$ degrees at AP radiograph in post-wearing state. Mean calcaneal pitch angle of right foot was $16.4{\pm}5.75$ left foot was $16.5{\pm}5.6$ degrees at lateral radiograph in post-wearing state. The radiographic angles between pre-wearing and post-wearing state were statistically significant (p<0.05). Mean pre-wearing AOFAS hindfoot score was $66.7{\pm}9.25$, midfoot score was $60.0{\pm}9.34$ forefoot score was $57.1{\pm}11.8$. Mean post-wearing AOFAS hindfoot score was $73.2{\pm}9.73$, midfoot score was $68.1{\pm}10.1$, forefoot score was $67.2{\pm}11.4$. The forefoot score was highest improving scores among the AOFAS scores. Conclusion: From our study, we concluded that medial arch support was effective for symptomatic flat feet of children in radiological and clinical results from our study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.2
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• pp.191-201
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• 2024

In this study, three-dimensional finite element analysis was used to analyze the behavior of existing and reinforcing piles according to the pile support conditions for vertical extension remodeling. Cap support conditions (group pile, piled raft foundation) and pile tip conditions (rock, soil embedment) were considered as factors influencing existing and reinforcing piles behavior. For the quantitative analysis of existing and reinforcing piles, the displacement, load distribution ratio, and axial force by depth according to the analysis stage were analyzed. As a result of the analysis, it was confirmed that the largest settlement occurred in the reinforcing pile due to the pre-loading method. In particular, a large amount of settlement occurred in group piles regardless of the embedment conditions. In the piled raft foundation, it was confirmed that the displacement and load distribution ratio of existing piles and reinforcing piles were reduced due to the influence of the raft. The axial force by depth showed a difference between group pile and piled raft foundation, which appears to be a major factor affecting displacement and load distribution ratio. Based on the numerical analysis results, it was confirmed that cap support conditions and pile tip embedment conditions should be considered in the design of pile foundations for vertical extension remodeling.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.301-309
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• 2011

Apartment housings that adopt a bearing wall structure design, which account for a majority of the housing units available in Korea, are not free from structural constraints that limit the extension of their service life. The resulting need for reconstruction from the ground up requires a massive consumption of resources and energy, and triggers environmental pollution resulting from construction wastes. As a solution to such issues, the government enforces incentive schemes to promote a remodeling-friendly rahmen structure design. Green Frame, which is a novel concept of composite precast concrete structure to support rahmen structure apartment housing buildings, can address the constraints of bearing wall structure and conventional rahmen structure designs that limit the potential for remodeling projects, while reducing the term of construction. Therefore, this study aims to analyze the characteristics of Green Frame and its absolute term of construction, and compare the terms of frame work construction in apartment housing projects adopting different structural design approaches to illuminate their differences. In the end, Green Frame is found to be capable of reducing the term of construction in apartment housing projects. As the term of construction is a very critical element of a construction project, Green Frame will ultimately prove to be one of the key enablers to ensure the success of apartment housing construction projects.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.863-874
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• 2015

The use of pile reinforcement is considered as one of the most promising techniques for improving load carrying capacity of piles in offshore area. In this study, to consider the horizontal and uplift bearing capacity of submerged breakwater bearing pile, exclusive analysis on load-transfer behaviour of pile was conducted. First of all, check the reinforcing effect from the three-dimensional finite element method, and estimate load transfer curve (ground reaction force). Based on these results, the reinforcing effect was quantified by estimating the coefficients of horizontal and uplift reinforcement of reinforced piles. Load transfer function with consideration of the reinforcing effect was proposed from estimated coefficients. A comparison of the analysis using the proposed load transfer function with three-dimensional finite element analysis has resulted that the proposed load transfer function is displaying good accuracy of predicting behavior of the load transfer between the pile and soil reinforcement. Interpretation of the submerged structure by applying a load transfer function considering the reinforcing effect, has shown that the reinforced pile's shear, bending moment and displacement are less than that of non-reinforced piles, while the subgrade reaction modulus arises greater. Thus, it is expected to be relatively cost effective in terms of design.

• Nutrition Research and Practice
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• v.9 no.2
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• pp.129-136
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• 2015

BACKGROUND/OBJECTIVES: A variety of immunomodulators can improve the efficacy of low-dose chemotherapeutics. Active hexose correlated compound (AHCC), a mushroom mycelia extract, has been shown to be a strong immunomodulator. Whether AHCC could enhance the antitumor effect of low-dose 5-fluorouracil (5-FU) via regulation of host immunity is unknown. MATERIALS/METHODS: In the current study Hepatoma 22 (H22) tumor-bearing mice were treated with PBS, 5-FU ($10mg{\cdot}kg^{-1}{\cdot}d^{-1}$, i.p), or AHCC ($360mg{\cdot}kg^{-1}{\cdot}d^{-1}$, i.g) plus 5-FU, respectively, for 5 d. $CD^{3+}$, $CD^{4+}$, $CD^{8+}$, and NK in peripheral blood were detected by flow cytometry. ALT, AST, BUN, and Cr levels were measured by biochemical assay. IL-2 and $TNF{\alpha}$ in serum were measured using the RIA kit and apoptosis of tumor was detected by TUNEL staining. Bax, Bcl-2, and TS protein levels were measured by immunohistochemical staining and mRNA level was evaluated by RT-PCR. RESULTS: Diet consumption and body weight showed that AHCC had no apparent toxicity. AHCC could reverse liver injury and myelosuppression induced by 5-FU (P < 0.05). Compared to mice treated with 5-FU, mice treated with AHCC plus 5-FU had higher thymus index, percentages of $CD^{3+}$, $CD^{4+}$, and NK cells (P < 0.01), and ratio of $CD^{4+}$/$CD^{8+}$ (P < 0.01) in peripheral blood. Radioimmunoassay showed that mice treated with AHCC plus 5-FU had the highest serum levels of IL-2 and $TNF{\alpha}$ compared with the vehicle group and 5-FU group. More importantly, the combination of AHCC and 5-FU produced a more potent antitumor effect (P < 0.05) and caused more severe apoptosis in tumor tissue (P < 0.05) compared with the 5-FU group. In addition, the combination of AHCC and 5-FU further up-regulated the expression of Bcl-2 associated X protein (Bax) (P < 0.01), while it down-regulated the expression of B cell lymphoma 2 (Bcl-2) (P < 0.01). CONCLUSIONS: These results support the claim that AHCC might be beneficial for cancer patients receiving chemotherapy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.106-111
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• 2017

In this study, the stiffness of an LMU (Leg Mating Unit), which is a device required for installing the top side part of an offshore structure, was examined through structural analysis. This unit is mounted on the supporting point of the structure and is used to absorb the shock at installation. It is a cylindrical structure with an empty center. To support the vertical load, elastomeric bearings (EBs) and iron plates are laminated in layers. The stiffness of the EBs is basically influenced by the size of the bearings, but it varies with the number of laminated sheets inside the same sized structure. The relationship between the stiffener and the compressive stiffness is investigated, and its design is suggested. The stiffness of the EBs is analyzed by calculating the reaction force, while controlling the displacement. First, the relationship between the size of the reinforcing plate and the compressive stiffness is considered. Next, the relationship between the number of stacked reinforcing plates and the compression stiffness is considered. Different loads are required for each installed point. The goal is to design the compression stiffness in such a way that the same deformation occurs at each point in the analysis. In this study, ANSYS is used to perform the FE analysis.

• The Journal of Engineering Geology
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• v.30 no.2
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• pp.185-198
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• 2020

High-density rapid expansion material is a method that increases the solid volume of injection materials due to hydration and foam reactions at the same time as spraying. It is an effective method for securing ground stability, restoring subsidence, and loading during construction of structures. In this regard, through the mechanical experiments of injection materials, the stability of the foundation ground of the structure and the effect of increasing the endurance using site construction were analyzed. The results of the experiment showed that the unit weight of soil decreased by 10.5% after injection of the filling material, and the allowable support for the structure was deemed safe, and the subsidence by each section after ground improvement was determined to be safe at 2.28, 1.55 and 0.46 cm, respectively, with an acceptable subsidence of less than 5 cm. After the field test, five inclinometers were installed on the top floor of the target building to measure the displacement of the X and Y axes. As a result of the measurement, no displacement related to the phenomenon of inequality or subsidence cracks of the structure was measured for about 16 months (509 days) after construction. This can be judged to be a sufficient increase in the stability of the ground after the injection of rapid expansion.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.124-135
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• 2011

The capacity of bearings installed at abutments and piers for continuous bridges is usually determined by the magnitude of the maximum vertical reaction at each support and the capacity of bearings placed at piers is higher than that at abutments. In this study, the possibility of the improved seismic performance of base-isolated continuous skew bridges was investigated by analysing the variation of the seismic behavior of them according to three arrangements of bearings. Based on the conventional arrangement of bearings(Case A), three arrangements of bearings such as Case A, Case B and Case C were selected considering the variation of the horizontal stiffness of the lead rubber bearing(LRB) installed at the pier. The seismic behavior of the total 36 skew bridges was investigated by conducting the response spectrum analysis using the hybrid response spectrum considered the effect of LRB's damping. Results of analyses show that a more desirable seismic behavior of base-isolated continuous skew bridges can be obtained by reducing the magnitude of the horizontal stiffness of LRB placed at the pier to similar to or less than that of LRB installed at abutments. The variation of LRB's stiffness at the pier brings about period elongation and the change of mode shapes of base-isolated skew bridges and results in the reduction of the total base shear, the maximum base shear at the pier and the girder stresses. Although positive effects on the seismic behavior of base-isolated skew bridges caused by the change of arrangement of bearings decreased slighty with an increase in the flexibility of the substructure, the proposed arrangements of bearings bring about the improved seismic performance of base-isolated continuous skew plate girder bridges with less than 10m height of piers.