• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.5-16
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• 2016

New PHC piles, where short steel pipes are attached to the pile toe, are developed to increase the base load capacity of bored pre-cast piles embedded in weathered rock. In this study, new bored pre-cast piles using the new PHC piles are installed at 7 test sites with different soil conditions, and static and dynamic pile load tests are performed to investigate quantitative characteristics on the base load capacity of new bored pre-cast piles. In addition, based on the static pile load test results, a new empirical equation for estimating the base load capacity of new bored pre-cast piles is proposed. A comparison between predicted and measured base load capacities shows that the proposed empirical equation produces conservative predictions for the new bored pre-cast piles. However, the existing design criterion significantly underestimates the base load capacity of new bored pre-cast piles.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.85-90
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• 2004

We divided the planting bale into waterproof layer, drainage layer and soil layer so at to investigate changes of live load according to species of wood and composition of the base to make rooftops green. The results are follows, 1. As concerning construction and live load for green roof, sheet waterproofing is superior. 2. When materials of drainage are changed crushed gravel into artificial lightweight graval or ferrite, live load of planting bale is decreased about 22% and 25% in order. 3. When ingredients of soil are chased normal sand into volcanic sand, live load of base is decreased about 28%. Especially, when it is changed into ferrite, 54% of live load is decreased. 4. In this study, all live load we concerned excesses the standard about roof live load of office, school and house. Hence, structure has to be concerned thoroughly when making rooftops green. But, we judge that various methods for making rooftops green can be applied if we consider roof garden when we plan new buildings.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.409-429
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• 2006

In designing rock-socketed drilled shaft, bearing capacity evaluation is very important because the maximum values of base and side resistance are not generally mobilized at the same value of displacement, FHWA and AASHTO code suggest different ultimate bearing capacity formular according to rock type and shaft settlement. In domestic code suggest base resistance and side resistance can be added on condition that after confirming the result of field load test with axial load transfer test. This paper shows that static load test and hi-directional load test result analysis of deep rock-socketed drilled shaft in three different sites. Load-settlement curve, t-z, and q-w curve in rock-socketed part were calculated and compared. t-z curve in weathered and soft rock showed no deflection softening behavior in pretty large strain (about 2-3% of diameter). Ultimate resistance could be the summation of side resistance and base resistance in rock-socketed drilled shaft in domestic sites.

• Wind and Structures
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• v.3 no.4
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• pp.279-289
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• 2000

The main purpose of this paper is to demonstrate the necessity of considering wind load combinations even for low-rise buildings. It first discusses the overall quasi-static wind load effects and their combinations to be considered in structural design of low-rise buildings. It was found that the maximum torsional moment closely correlates with the maximum along-wind base shear. It was also found that the instantaneous pressure distribution causing the maximum along-wind base shear was quite similar to that causing the maximum torsional moment, and that this asymmetric pressure pattern simultaneously accompanies considerable across-wind and torsional components. Secondly, the actual wind pressure distributions causing maximum quasi-static internal forces in the structural frames are conditionally sampled and their typical pressure patterns are presented.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.53-63
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• 2013

Bored pre-cast piles using PHC piles is widely used in foundation of building structures constructed in urban areas because noise and vibration due to pile installation are low. However, since slime is formed at the base of borehole and the density of bearing stratum surrounding the base of borehole is decreased due to stress relaxation in drilling process of bored pre-cast pile method, the base load capacity of bored pre-cast piles is very low compared to the strength of bearing stratum. In this study, a new type of PHC pile, which short steel pipe with the same diameter as the PHC pile is attached to the pile tip, is developed to increase the base load capacity of bored pre-cast piles. In order to check the effect of the use of new PHC pile on the base load capacity of bored pre-cast piles, field pile load tests are performed for bored pre-cast piles using the new and existing PHC piles. Results of the pile load tests show that the new PHC pile gives higher base load capacity to bored pre-cast piles than the existing PHC pile, since the tip of new PHC pile is penetrated to undisturbed bearing stratum passing through the slime at the base of borehole and the loosened bearing stratum under the slime by pile driving using light hammer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.97-105
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• 2014

This article examines the causality relationship among SMP, base-load share, LNG import price, and exchange rate in Korean power market during 2002~2012, using unit root test, cointegration test, and vector error correction model(VECM). The cointegration test shows that 4 variables without unit root have been in the long-run causality. As the results of ECM, SMP is analyzed to have been unilaterally caused from LNG import price and base-load share in the shot-run, while it has been unilaterally caused from LNG import price and exchange rate in the long-run. This article has the following policy implications: the adjustment of exchange rate to reduce he risk of LNG import price and the proper securement of base-load share for the long-run stability of SMP.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.249-258
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• 1999

Dynamic load and static load tests are performed on steel pipe piles and concrete piles at five construction sites in highway to compare the difference of load bearing mechanisms. At each site, one steel pile is instrumented with electric strain gages and dynamic tests are performed on the pile during installation. Damages of strain gages due to the installation are checked and static test is performed upon the same pile after two or seven days as well. It shows that load transfer from side friction to base resistance behaves somewhat differently according to the results of load-settlement analysis obtained from PDA and static load test. Initial elastic stage of load settlement curves of two load tests is almost similar. But after the yielding point, dynamic resistance of pile behaves more stiffer than static resistance, thus, dynamic load test result might overestimate the real pile capacity compared with static result. Analysis of gage readings shows that unit skin friction increases exponentially with depth. The skin friction is mobilized at the 1∼2m above the pile tip and contributes to the considerable side resistance. Comparison of side and base resistances between the measured value and the calculated value by Meyerhof's bearing capacity equation using SPT N value shows that the calculated base resistance is higher than the measured. Therefore, contribution of side resistance to total capacity shouldn't be ignored or underestimated. Finally, based upon the overall test results, a construction control procedure is suggested.

• Journal of Industrial Technology
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• v.19
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• pp.135-145
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• 1999

This thesis is to investigate the sliding behavior of cantilever retaining wall by using the commercially available program of FLAC to simulate its behavior numerically. Cantilever retaining walls with flat base, sloped base and base with shear key, uniform surcharges being applied on the surface of backfill, were investigated to figure out appropriate location of shear key beneath the base of wall and, thus, its applicability to field condition was assessed by comparing the analyzed results to each other. On the other hand, previously performed centrifuge model test results (Eum, 1996) were analyzed numerically with FLAC to compare test results with respect to characteristics of load-settlement of surcharges and load-lateral movement of wall. Based on the failure mechanism observed during centrifuge tests, limit equilibrium method of finding the ultimate load inducing the sliding failure of wall was used to compare with values of the ultimate load obtained from conventional method of limit equilibrium method. Therefore, appropriate location of shear key was determined to mobilize the maximum resistance against sliding failure of wall.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.255-257
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• 2007

Korea electricity market consists of two payment systems, capacity and energy. Capacity payments are given to the generators according to its hourly availability considering hourly and seasonal weighting factors. Energy payments are settled at the marginal generation cost based on generator variable cost. In 2007, base load energy market is closed and single capacity payment system is begun to apply in electricity market. In this revised market rule, energy price cap for base load generators is newly introduced. We analyze impact of market rule revision in 2007 on base load generators and suggest improvement scheme to enforce market system in this study.

• 전기의세계
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• v.31 no.5
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• pp.368-374
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• 1982

This paper describes a combined algorithm for short-term-load forecating. One of the specific features of this algorithm is that the base, weather sensitive and residual components are predicted respectively. The base load is represented by the exponential smoothing approach and residual load is represented by the Box-Jenkins methodology. The weather sensitive load models are developed according to the information of temperature and discomfort index. This method was applied to Korea Electric Company and results for test periods up to three years are given.