• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.123-132
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• 2008

Aseries of in-situ tests and ground water level measurements with stone and slug materials had been conducted to find out effect of ground settlement reduction and bearing capacity improvement by the Stone Column method. As the result of the tests, it was proved that the Stone Column method is effective for reduction of ground settlement and improvement of bearing capacity. In addition the ground water level went down without overburden load. These results show that the Stone Column method is effective for an increase in density and resistance to liquefaction. The results of estimation of ground settlement and bearing capacity by general theoretical equation, it show that the Stone Column method increases bearing capacity by 2.7~5.7 times and decreases ground settlement by 2~3.5 times.

• Steel and Composite Structures
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• v.4 no.2
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• pp.149-167
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• 2004

Offshore platforms have to serve in harsh environments and hence are likely to be damaged due to wave induced fatigue and environmental corrosion. Welded tubular joints in offshore platforms are most vulnerable to fatigue damage. Such damages endanger the integrity of the structure. Therefore it is all the more essential to assess the capacity of damaged structure from the point of view of its safety. Eight internally ring stiffened fatigue damaged tubular joints with nominal chord and brace diameter of 324 mm and 219 mm respectively and thickness 12 mm and 8 mm respectively were tested under axial brace compression loading to evaluate the reserve capacity of the joints. These joints had earlier been tested under fatigue loading under corrosive environments of synthetic sea water and hence they have been cracked. The extent of the damage varied from 35 to 50 per cent. One stiffened joint was also tested under axial brace tension loading. The residual strength of fatigue damaged stiffened joint tested under tension loading was observed to be less than one fourth of that tested under compression loading. It was observed in this experimental investigation that in the damaged condition, the joints possessed an in-built load-transfer mechanism. A bi-linear stress-strain model was developed in this investigation to predict the reserve capacity of the joint. This model considered the strain hardening effect. Close agreement was observed between the experimental and predicted results. The paper presents in detail the experimental investigation and the development of the analytical model to predict the reserve capacity of internally ring stiffened joints.

• Structural Engineering and Mechanics
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• v.78 no.5
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• pp.623-635
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• 2021

Previous studies have suggested the maximum experimental story shear force of beam-column joint frame does not reach its theoretical value due to beam-column joint failure when the column-to-beam moment capacity ratio was close to 1.0. It was also pointed out that under a certain amount of axial force, an axial collapse and a sudden decrease of lateral load-carrying capacity may occur at the joint. Although increasing joint transverse reinforcement could improve the lateral load-carrying capacity and axial load-carrying capacity of beam-column joint frame, the conditions considering varying axial force were still not well investigated. For this purpose, 7 full-scale specimens with no-axial force and 14 half-scale specimens with varying axial force are designed and subjected to static loading tests. Comparing the experimental results of the two types of specimens, it has indicated that introducing the varying axial force leads to a reduction of the required joint transverse reinforcement ratio which can avoid the beam-column joint failure. For specimens with varying axial force, to prevent beam-column joint failure and axial collapse, the lower limit of joint transverse reinforcement ratio is acquired when given a column-to-beam moment capacity ratio.

• Journal of the Korea Convergence Society
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• v.8 no.1
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• pp.203-212
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• 2017

Under uncertain environments it is necessary for world-class technological capacity to obtain for making the important role in a national development and industrial infrastructure. For strengthening technological capacity based on R&D excellence we have an exploratory study on the cases of excellent technology and excellent organization of public R&D institutes. What consistently revealed in the whole cases of public R&D institutes is to obtain the technological capacity in the world-class level and we could verify it in the cases of global leading technology, flagship project, world innovative technology, world class laboratory, global top group and so on. For enhancing the technological capacity of R&D objects we could consider prospecting sustainedly for the technological capacity of the organizations in order to appear the excellent technological performance, industrializing it as a R&D program or a new growth engine, and forming the organizational consensus of recognizing its technology or organization they selected as the world-class level.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.295-309
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• 2019

This paper demonstrates that the verification and analysis of the increase of hosting capacity of distributed energy resources in distribution system for the high penetration of distributed energy resources. In the case of generally designed distribution feeders in South Korea, it can host up to 10 MVA of distributed energy resources and the over voltage due to reverse power flow is prohibited beyond the range by the law of electric utility. However, it should take into consideration that there are some factors of extra hosting capacity such as generation characteristics of distributed energy resources and minimum loads that always exist to distribution system. For these reason, we choose a specific distribution system hosted 10 MVA of distributed energy resources monitored by distribution system operator and verify the impact of increasing hosting capacity such as power flow and voltage profile of distribution system. By the result, we could find that it is possible to increase the hosting capacity and define the factors to expand the hosting capacity of distributed energy resources in distribution system.

• Steel and Composite Structures
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• v.20 no.1
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• pp.91-106
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• 2016

Two-dimensional elastoplastic finite element formulation is employed to investigate the load- carrying capacity degradation of reinforced concrete piers wrapped with steel plates due to occurrence of corrosion at the pier base. By comparing with experimental results, the employed finite element analysis method is verified to be accurate. After that, a series of parametric studies are conducted to investigate the effect of corrosion ratio and corrosion mode of steel plates located near the base of in-service pier P2 on load-carrying capacity of the piers. It is observed that the load-carrying capacity of the piers decreases with the increase in corrosion ratio of steel plates. There exists an obvious linear relationship between the load-carrying capacity and the corrosion ratio in the case of even corrosion mode. The degradation of load-carrying capacity resulted from the web's uneven corrosion mode is more serious than that under even corrosion mode, and the former case is more liable to occur than the latter case in actual engineering application. Finally, the failure modes of the piers under different corrosion state are discussed. It is found that the principal tensile strain of concrete and yield range of steel plates are distributed within a wide range in the case of slight corrosion, and they are concentrated on the column base when complete corrosion occurs. The findings obtained from the present study can provide a useful reference for the maintenance and strengthening of the in-service piers.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.802-807
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• 1998

The main drawback of parallel type active power filters (APF) is the large capacity required for harmonic compensation. This paper evaluates the APF capacity requirement of harmonic/reactive power compensation for thyristor converter load. Theoretically achievable maximum power factor under partial load is evaluated. And it is shown that the APF capacity can be considerably reduced while slightly sacrificing the filtering performance by deliberately limiting the peak current of the APF.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.122-126
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• 1996

In this thesis, the field test results of fifty-one highway bridges were analyzed in order to Investigate the primary capacity of load of highway bridges. From this study, it was known that primary capacity of load are decreased with the serviced years, and those are small in T-beam bridges rather than I-beam bridges. And the average primary capacity of load of highway bridges is seemd about 15. 5ton in T-beam bridges and in I-beam bridges about 19.7ton.

• Proceedings of the Korea Society for Simulation Conference
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• 1992.10a
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• pp.1-1
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• 1992

This paper presents a user-oriented port expansion simulation model that determines the future economic port capacity to meet the projected demand. The model consists of two parts; a physical impact simulation, and an economic impact simulation. The first part of the model simulates the effects caused by the port capacity expansion. The second part evaluates the port economics due to changes in the port capacity. The model was validated by applying it to the actual port expansion followed at the Port of Mobile, Alabama. A case study is then presented to demonstrate the capacity of the model with a coal handling port, the McDuffie Terminals at the Port of Mobile.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.730-735
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• 2014

In this study, the temperature characteristics of electrostatic capacity and dielectric loss for the sample of Teflon film which is degradated at the $120^{\circ}C{\sim}200^{\circ}C$ temperature range in the oven for 10 hours has been measured in through the applied frequency range of 0.1 kHz~4,800 kHz at temperature of $50^{\circ}C$, $90^{\circ}C$, $130^{\circ}C$, $170^{\circ}C$. Also, in the same conditions, the frequency characteristics of electrostatic capacity and dielectric loss for the sample of Teflon film has been measured in through the applied temperature range of $30^{\circ}C{\sim}70^{\circ}C$ on setting frequency of 0.1 kHz, 1 kHz, 10 kHz, 100 kHz. The results of this study are as follows. When the frequency range of 0.1 kHz~4,800 kHz applied to the sample of Teflon film, the electrostatic capacity has been measured at the temperature of $50^{\circ}C$, $90^{\circ}C$, $130^{\circ}C$, $170^{\circ}C$. Through this measurement, it found that the electrostatic capacity decreased with increasing temperature. Regarding this result, may be it is because the electromagnetic coupling is degraded by thermal degradation. When the sample of Teflon film heated at $280^{\circ}C$ for 10 hours in oven, the dielectric loss has changed from unstable status to stabilizing status with increasing the degradation temperature in the $120^{\circ}C$, $160^{\circ}C$, $200^{\circ}C$ range. In this measurement, the two spectrums of dielectric loss appeared. It considers that this spectrum of dielectric loss appeared in 300 Hz is caused by the molecular motion of the C-F or OH group. Through this study, It found that the electrostatic capacity decreased with increasing frequency and temperature, and there is no change in dielectric loss, although the frequency increases.