• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.273-279
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• 2011

The yield strength of particle-reinforced composites increases as the size of the particle decreases. This kind of length scale has been mainly attributed to the geometrically necessary dislocation punched around the particle as a result of the mismatch of the thermal expansion coefficients of the particle and the matrix when the composites are cooled down after consolidation. In this study, two dislocation-punching theories that can be used in continuum structural modeling are assessed numerically. The two theories, presented by Shibata et al. and Dunand and Mortensen, calculate the size of the dislocationpunched zone. The composite yield strengths predicted by finite element analysis were qualitatively compared with experimental results. When the size of the particle is less than $2{\mu}m$, the patterns of the composite strength are quite different. The results obtained by Shibata et al. are in qualitatively better agreement with the experimental results.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.223-233
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• 2003

Sand compaction pile (SCP) is one of the ground improvement techniques which are being used for not only accelerating consolidation but also increasing bearing capacity of loose sands or soft clay grounds. In this study, laboratory model tests and 3-D finite element analyses were performed to investigate the interaction between sand compaction piles and surrounding soft soils. Based on the results obtained, as the area replacement ratio increases, the stress concentration ratio increases at the pile point, the settlement decreases, and the relative displacement between column and soil also decreases. It is also found that numerical study is illustrated by good comparison with model test results, and the numerical analysis revealed slip effects which could not be specifically identified in the model tests.

• Journal of Korean Elementary Science Education
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• v.25 no.4
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• pp.339-351
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• 2006

The purpose of this study was to analyze the processes of observation teaching and the types of observation in elementary life science class. For the purposes of this study, 40 teachers majoring in elementary science education participated in surveys on the processes of observation teaching. In addition, after videotaping the observation classes conducted by three teachers, each teaching in the 3rd to 5th grade, and their one hundred and eight students, we analyzed the processes of observation teaching. As a result, the processes of observation leaching in elementary science class were categorized into 12 stages (motivation, stating the objective, recognizing objects to observe, free and subjective observation, introducing ways to observe, observing by the simple way, introducing additional ways, observing by the manipulative way, making a note of observation, looking over the contents of observation, finding regularities, consolidation). In the types of observation, teachers and students performed mostly simple observing by the visual way. Teachers introduced time-independent/non-compared/whole observing; students concentrated on time-independent/non-compared/particular observing as targets. Thus, students carried out observing in the types of observation that teachers had presented. Consequently, the analysis about the processes of observation teaching can establish an effective teaching program for observing in scientific activities by reconstructing its observing target and suitable topic. The analysis about the types of observation can be applied to set up strategies for improving observation skills.

• Journal of the Korean GEO-environmental Society
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• v.13 no.4
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• pp.77-91
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• 2012

Recently, construction of housing sites, complexes, roads, ports and airports is increasing for high-intensity use of the country and balanced development between regions. Presently, constructions are being conducted at soft ground. Consequently, engineering problems as long-term settlement of the ground, differential settlement, local structural damage have been reported consistently at construction site. In particular, long-term subsidence of the ground as various constructions and loads by the load will necessarily occur in the soft ground of west-south coast and inland coast. Therefore, in this study, regional proper analysis methods of the Hyperbole method, Hosino method, $\sqrt{S}$ method, Asaoka method etc as existing long-term settlement prediction methods have been examined and a study on new prediction method was conducted through deduction of a generalized equation. Correlation coefficients of soil properties and construction conditions has been analyzed and a matching coefficient of long-term settlement characteristics has been deducted. Comparison and analysis of monitoring data and numerical analysis results of 16 local area have been conducted.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.2
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• pp.218-227
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• 2014

In this paper, it performed to the elastic-plastic large deflection series analysis using the experimental model and predicted a failure mode and ultimate strength. The collapse mode of numerical analysis model is formed a plastic hinge on loaded flange and consistent with the collapse mode of experimental model. Also, The yield line is formed in the web could observed that have occurred the crippling collapse mode and the ultimate loads of the experimental model and numerical analysis model have maintained linearly Means 1.07, Standard deviation 0.04, Coefficient of variation(COV) 0.04 and the result of ultimate loads have appeared approximately 8% error rate. it was found that very satisfied to the experimental results and the applied rules. if it is considered to be maintain a reasonable safety level, it is possible to predict the failure modes of aluminium alloy plate girders and ultimate loads.

• Composites Research
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• v.36 no.5
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• pp.321-328
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• 2023

This study developed the in-situ stamp-forming process using the multi-axis robotic arm to fabricate thermal composite parts. Optimal fabrication parameters with the multi-axis robotic arm were determined using finite element analysis and these parameters were further refined through the practical manufacturing process. A comparison between the manufactured parts and finite element analysis results was conducted regarding thickness uniformity and wrinkle distribution to confirm the validity of the finite element analysis. Additionally, to evaluate the formability of the manufactured composite parts, measurements of crystallinity and porosity were taken. Consequently, this study establishes the feasibility of the In-situ stamp-forming consolidation using a robotic arm and verifies the potential for producing composite parts through this process.

• Journal of the Korean Geosynthetics Society
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• v.19 no.3
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• pp.9-21
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• 2020

In this study, the design method of the combined sheet pile was considered in the coastal landfill where sandy and clayey soils are mixed, and the behavior in excavation was analyzed. It was confirmed from the elasto-plastic analysis that the predicted behavior of the temporary facilities of earth retaining differs according to the type of the combined sheet pile method (Built up, Interlocking, Welding) and the analysis method (soldier pile method, continuous wall method). In the case of sheet pile member force, the results of the continuous wall analysis method predicted the most conservative results. When the stress ratio (calculation/allowance) of each member was analyzed based on the maximum member force of the combined sheet pile method, the maximum value was obtained for bending moment in the side pile and combined stress in the case of the strut. As a result of finite element analysis, the member force of the side pile was the largest in the short-term effective stress analysis condition, while the compressive force of the strut was large in the consolidation analysis. When comparing the results of the elasto-plastic analysis and the finite element analysis, the shear force of the side pile and the axial force of the strut were greatly evaluated in the elasto-plastic analysis, and the bending moment of the side pile was the largest in the short-term effective stress condition of the finite element analysis. In addition, the displacement of the side pile was predicted to be greater in the finite element analysis than in the elasto-plastic analysis.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.5-17
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• 2005

Spatial uncertainty of Busan marine clay ground, which commonly occurs during site investigation testing, data analysis and transformation modeling, has been described. In this paper geotechnical uncertainty of shear strength indicator $N_k$ has been quantified in both horizontal direction and vertical direction using geostatistical Kriging method. Most of soil data used are from 25 boring tests, 75 laboratory tests, 124 field vane tests and 25 cone penetration tests (CPT). CPT-$N_k$ data for undrained shear strength determination, which are the most important properties in geotechnical design stages, have been analysed. Comparison between cone factor from conventional CPT-based method and that of geostatistical method shows that geostatistical Kriging method is an ideal tool to quantify the spatial variability of uncertainty from self-correlation of soil property of interest, and can be recommended to identify the spatial distribution of consolidation .md shear strength of soils at any sites concerned.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1136-1142
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• 2012

With concern for new renewable energy sources rising, the offshore wind turbine energy market is growing. In order to install offshore wind turbines safely in a harsh environment, jack-up rigs need to be used. Recently, a WTIV(Wind Turbine Installation Vessel), which has a self-propelling system, was developed to replace traditional jack-up rigs. Since the jack-up rig works at 60 meters of depth in offshore and the seafloor is composed mostly of soft clay and sand, it is necessary to conduct a stability examination for ground subsidence before using it. This study conducts an improved numerical analysis of the effect of jack-up rig loading on the soft ground by using FLAC3D considering consolidation theory. This includes analyzing the amount of subsidence when applying different cases of surchargings. It can be concluded that the mid-loading method has an advantage as regards clay layers and the pre-loading method has an advantage as regards sand layers.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.5
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• pp.391-399
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• 2004

Distraction osteogenesis has been thought to be promising technique for replacing bone graft in maxilla and mandible. The purpose of this study was to investigate the expression of osteonectin on distraction osteogenesis. Sixteen rabbits were used for this experiment. Osteotomy was performed between premolar and mental foramen. On the experimental group, distraction device was connected to the respective bone segments. On the control group, bone segments were fixed using plate and screws after osteotomy. Distraction was carried out at the rate of 0.7mm per day to obtain a 4.9mm elongation on the experimental group. After 3 days, 7 days, 14 days, and 28 days two rabbits of each group were sacrificed. The results obtained from this study were as follow : Experimental group was observed that the gaps between the distracted bone edges were occupied by new bone. Expression of Osteonectin were detected throughout the experiment in both groups and Expression of Osteonectin were markedly increased during distraction and consolidation period in experimental group than control group. From these results, it could be stated that distraction was shown to improve and accelerate bone formation and mechanical stress like distraction has considerable effects on osteonectin.