• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.84-91
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• 2002

Temperature distribution in the GTD111 turbine blade used in power plaints is calculated by heat transfer analysis. Linear stress analysis of the turbine blade is also carried out under thermal loads and centrifugal forces. The numerical results of steady state heat transfer analysis slow that high temperature distribution occurs at the leading edge and tip section of the blade. The thermal stress result indicates that the equivalent stress at the tip of the pressure surface is higher than other sections of the blade. Maximum centrifugal stresses without the thermal effect occurs at the front of the fir tree. From the thermal-centrifugal stress analysis, maximum equivalent stress occurs at the fir tree. Stresses applied by the thermal loads and centrifugal forces are less than the yield stress. The GTD111 turbine blade is safe to be used in the power plants.

• Journal of the Korean Geotechnical Society
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• v.22 no.1
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• pp.25-34
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• 2006

In this study an effective stress numerical procedure is used to assess the results of dynamic centrifuge tests under high effective stress. The centrifuge models consist of loose Nevada sand with an initial vertical effective stress of 380kPa at depth, and they are modeled as a one-dimentional soil column. Liquefaction occurred up to 37m or 22m at depth, and the onset of liquefaction triggering was opposite to the conventional liquefaction evaluation procedure. In other words, liquefaction occurs first at the top and propagates downward as shaking continues. The results observed in centrifuge tests are reasonably predicted by the effective stress model. It is noted that the degree of initial saturation and additional densification at depth arising from the application of the high acceleration field play a key role in capturing the results of dynamic centrifuge tests.

• Journal of the Korean GEO-environmental Society
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• v.7 no.5
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• pp.57-66
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• 2006

In this study, the centrifuge model tests were carried out to evaluate the stress concentration ratio, the deformation modes of piles and the ground movement in clay deposit improved by SCP and GCP piles with changing the replacement ratio(20%, 40%, 60%) under flexible loading. Based on the results obtained, it was shown that the stresses acting on GCP was larger than those acting on SCP with the same replacement ratio. It was evaluated that the average stress concentration ratio of soft clay ground improved by GCP was slightly larger than that of SCP when the replacement ratio is 40%. Only expansion failure occurred in GCP, whereas SCP showed the expansion and shear failure simultaneously.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1C
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• pp.19-24
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• 2006

In this study, centrifugal model tests were performed to evaluate the stress sharing between SCP and surrounding clayey soil at composite ground improved by sand compaction pile with the low area replacement ratio. The SCPs were formed by the "frozen pile" method and pressure cells were installed on pile and surrounding clayey soil to observe stress sharing characteristics. As a result of centrifugal tests, it is shown that the value of stress concentration ratio is mainly affected by area replacement ratio, loading condition and elapsed time.

• The korean journal of orthodontics
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• v.32 no.5 s.94
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• pp.343-353
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• 2002

This study was designed to investigate the stress distribution of alveolar bone in case of on masse retraction with lingual K-loop archwire using the 3-dimensional photoelastic stress analysis followed by stress freezing process. Lingual K-loop archwire which had loop in 15mm height was used and activated by retraction force of 350gm per each side. The results were as follows 1. Central incisor : As the closer side to crown, the larger tensile stress was distributed at both mesial and labial surfaces and the larger compressive stress was distributed at distal surface. As the closer side to root apex, the larger compressive stress was distributed at lingual surface. The compressive stress was distributed at root apex. 2. Lateral incisor : The tensile stress was distributed at the coronal side of mesial surface. The compressive stress was distributed at distal surface. As the closer side to crown, the larger tensile stress was distributed at labial surface. The tensile stress was distributed at coronal side and the compressive stress was distributed at apical side of lingual surface. The compressive stress was distributed at root apex. 3. Canine The tensile stress was distributed at coronal side and the compressive stress was distributed at apical side of mesial surface. The tensile stress was distributed at distal surface. As the closer side to crown, the larger tensile stress was distributed at both mesial and distal surfaces. The compressive stress was distributed at root apex. 4. Second premolar : The tensile stress was distributed at mesial surface. The compressive stress was distributed at coronal side and the tensile stress was distributed at apical side of distal surface. The compressive stress was distributed at coronal side of buccal surface. As the closer side to crown, the larger tensile stress was distributed at lingual surface. The compressive stress was distributed at root apex. 5. First molar . As the closer side to crown, the larger tensile stress was distributed at both mesial and distal surfaces. No stress was distributed at buccal surface and palatal root apex. As the closer side to crown, the larger tensile stress was distributed at both lingual surfaces. The compressive stress was distributed a4 buccal root apexes. 6. Second molar The compressive stress was distributed at all root apexes. As the closer side to crown, the larger compressive stress was distributed at both mesial and lingual surfaces, and the larger tensile stress at both distal and buccal surfaces. Transverse bowing effect was observed in on-masse retraction with lingual K-loop archwire, however vertical towing effect was not. Rather, reverse vortical bowing effect was developed.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.45-55
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• 2008

In this study, the in-situ model test has been conducted to estimate and analyze consolidation behavior of the ground by using the miniature test that reconstructs economically geotechnical behavior of in-situ full scale structure. To analyze the relation of effective stress, void ratio and coefficient of permeability at the self-weight consolidation stage, the low stress seepage consolidation test has been conducted and the involution function of constitutive equation had been obtained from the result of the curve fitted seepage consolidation test. As a result of the numerical analysis that had been conducted on the representative section using a constitute equation, final settlement was similar to those of self-weight consolidation of the centrifugal model test. But it was more or less smaller. It seems that these trends are caused by the difference between estimated values.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.151-158
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• 2006

Centrifuge tests have shown that a uniformly placed sand layer will first initiate liquefaction near the surface and that liquefaction will progress downward during shaking. This appears to be in conflict with the overburden stress effect on soil liquefaction (i.e., $K_0$ effect) observed in laboratory testing. This discrepancy can be explained by stress-induced densification at depth which overcomes the effect of confining stress on liquefaction resistance. Stress densification occurs in centrifuge model tests but its effect has generally not been considered when preparing or evaluating centrifuge models. A new centrifuge model preparation method is proposed by considering stress-induced densification upon spin-up. The proposed method can be used to explore $K_0$ effects. The method is supported in this study by numerical predictions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.631-642
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• 2013

The standard CPT(Cone Penetration Test), which can be easily performed to investigate in-situ soil engineering properties, has been widely used. CPT are also widely being utilized in centrifuge model tests. In this study, a miniature cone with 10mm diameter was developed and its applicability in the centrifuge was evaluated. The developed miniature cone was equipped with a four degree-of-freedom in-flight robot. A series of cone penetration tests was performed under four centrifuge acceleration levels. As results, the cone resistances measured at the same confining stress within shallow penetration depth were affected by the centrifugal accelerations. The critical depth was proportional to the cone diameter and relative density. Cone resistances results below the critical depth and soil parameters obtained from the laboratory tests were compared with those by previously proposed empirical relations.

• The KSFM Journal of Fluid Machinery
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• v.16 no.6
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• pp.26-31
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• 2013

Last blades of low-pressure turbine in nuclear power plant are the highly damaged part and always suffered from different types of loadings leading to various stress components, stresses due to centrifugal force and steam flow loading. Especially, centrifugal stress generated by turbine rotation is one of the main problems and more significant than other stresses as they have the greatest effect on total stress. Therefore, this study was performed to obtain the important information for estimation model development of the blade centrifugal stress level and distribution.

• Journal of the Geological Society of Korea
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• v.54 no.6
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• pp.605-614
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• 2018

For physical experiments like analogue modeling that designed for studying geological deformation, reproducibility of the deformation is important to guarantee the reliability of the experiment. In this study, the normal fault generated by extensional stress is benchmarked using a sand box model. The scaling factors for the modeling test are considered and the experiments are conducted by setting the appropriate material, extensional stress, and boundary condition in the same way as in a benchmark experiment. In addition, a large centrifuge facility is used to vary the centrifugal acceleration and extension rate in the same sized model to account for the scaling factors of the physical quantity during extensional behavior. At 1 g benchmark condition and a centrifugal field at 10 g, a constant rate of the extensional stress is implemented and the topographic evolution is reliably measured. In this study, the reliability and applicability of large centrifuge model tests are evaluated for formulating experiments designed to study geological deformation.