• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.51-61
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• 2000

This paper reviews fundamentals of a pseudo-static seismic design/analysis method for soil-reinforced segmental retaining walls. A comparative study on NCMA and FHWA seismic design guidelines, which are one of the most well known design guidelines for mechanically stabilized earth walls, was also performed. The results demonstrate that there exist significant discrepancies in the results of external stability analysis despite the same calculation model used in the two guidelines, due primarily to different seismic coefficient selection criteria. It is also demonstrated that the internal stability calculation model for NCMA guideline tends to yield larger seismic reinforcement force in the shallower reinforcement layers, resulting in an increased number of reinforcement layers at the top of reinforced wall and increased reinforcement lengths to ensure adequate anchorage capacity. The internal stability calculation model adopted by FHWA guideline, however, leads to redistribution of dynamic force to the lower reinforcement layers and thus results n an opposite trend of NCMA guideline. Findings from this study clearly demonstrate a need for more in-depth studies to develop a generally acceptable design/analysis method.

• Convergence Security Journal
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• v.14 no.3_1
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• pp.3-9
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• 2014

NCOs of the amy-navy-air force are the foundation in maintaining, developing and leading the army making manpower aquisition very important. Currently, the operation or the recruitment business is being overlapped by each training institutions leading to uneffectively decreasing the curiosities of the applicants regarding their future. Even though the NCO selection policy is strong in the aspect of retaining uniqueness, use of acquired specialist, and statute revision, it is showing insufficiency in publicizing, selection effectiveness, promotion of peoples' conveniency, and budget reduction. Therefore, if the unification regarding the recruitment of each military sectors are run by the MMA(Military Manpower Administration), which is the institute that is fully responsible for the recruitment duty, it can acquire excellent man power while decreasing effort and resources, provide accurate information to the NCO applicants on time, and provide improved services through the convenient facilities and systems.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.2
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• pp.57-70
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• 2003

The study was conducted to present the criteria of plant selection and planting design pattern suitable for the vegetation blocks which are becoming more popular for the facade greenery in urban areas. The main results are summarized as follows. 1. Under irrigated conditions, the plant grew better than that of unirrigated conditions and herbs grew better than shrubs. In selection of shrubs, it would be more proper to consider the size and depth of the pockets. 2. Under unirrigated conditions, Sedum middendorffianum and foreign sedums grew well, so it can be concluded that sedums can grow at low management condition. And, Hosta longipes and Aceriphyllum rossii could be survive at low management conditions only if irrigation was conducted at dry season. But, shrubs needed irrigation management for survival at vegetation blocks. 3. The results of this study, it can be concluded that greenery of walls and retaining walls might be effective for the creation of green space, improvement of urban landscapes, and the creation of diverse biotopes in urban areas with vegetation blocks.

• Atmosphere
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• v.22 no.2
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• pp.149-161
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• 2012

Going by the research results of the past, of all the uncertainties resulting from the research on climate change, the uncertainty caused by the climate change scenario has the highest degree of uncertainty. Therefore, depending upon what kind of climate change scenario one adopts, the projection of the water resources in the future will differ significantly. As a matter of principle, it is highly recommended to utilize all the GCM scenarios offered by the IPCC. However, this could be considered to be an impractical alternative if a decision has to be made at an action officer's level. Hence, as an alternative, it is deemed necessary to select several scenarios so as to express the possible number of cases to the maximum extent possible. The objective standards in selecting the climate change scenarios have not been properly established and the scenarios have been selected, either at random or subject to the researcher's discretion. In this research, a new scenario selection process, in which it is possible to have the effect of having utilized all the possible scenarios, with using only a few principal scenarios and maintaining some of the uncertainties, has been suggested. In this research, the use of cluster analysis and the selection of a representative scenario in each cluster have efficiently reduced the number of climate change scenarios. In the cluster analysis method, the K-means clustering method, which takes advantage of the statistical features of scenarios has been employed; in the selection of a representative scenario in each cluster, the selection method was analyzed and reviewed and the PDF method was used to select the best scenarios with the closest simulation accuracy and the principal scenarios that is suggested by this research. In the selection of the best scenarios, it has been shown that the GCM scenario which demonstrated high level of simulation accuracy in the past need not necessarily demonstrate the similarly high level of simulation accuracy in the future and various GCM scenarios were selected for the principal scenarios. Secondly, the "Maximum entropy" which can quantify the uncertainties of the climate change scenario has been used to both quantify and compare the uncertainties associated with all the scenarios, best scenarios and the principal scenarios. Comparison has shown that the principal scenarios do maintain and are able to better explain the uncertainties of all the scenarios than the best scenarios. Therefore, through the scenario selection process, it has been proven that the principal scenarios have the effect of having utilized all the scenarios and retaining the uncertainties associated with the climate change to the maximum extent possible, while reducing the number of scenarios at the same time. Lastly, the climate change scenario most suitable for the climate on the Korean peninsula has been suggested. Through the scenario selection process, of all the scenarios found in the 4th IPCC report, principal climate change scenarios, which are suitable for the Korean peninsula and maintain most of the uncertainties, have been suggested. Therefore, it is assessed that the use of the scenario most suitable for the future projection of water resources on the Korean peninsula will be able to provide the projection of the water resources management that maintains more than 70~80% level of uncertainties of all the scenarios.

• Journal of Korean Library and Information Science Society
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• v.27
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• pp.423-456
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• 1997

As information technology has been evolving, digital library emerges as a vision of future library. Many authors on digital library describe that the problems that today's libraries face would be completely solved by using digital technology. But it is su n.0, pposed that such technology oriented papers do not take care of what the library has been and should remain. This paper is prepared to identify what core elements of library services being provided in traditional environment must be transferred to the digital library. For this purpose, firstly historical transition from traditional library to digital discussed. Secondly, library's fundamental service functions are analysed from three points of view-library as cultural and social institution, library as intellectual reality, library as a collection. And 'control zone' concept is also investigated as a new possibility of academic digital libraries. In contrast to open zone in which information is not controled at all as in internet, in control zone, information is selected and maintained by academic library community, retaining such essential library functions as selection.

• KDI Journal of Economic Policy
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• v.40 no.3
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• pp.69-89
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• 2018

We study whether a default option attached to non-recourse mortgages improves borrowers' surplus from mortgage financing. By defaulting on mortgage debt, borrowers can save their non-collateralized income from being foreclosed. In exchange, borrowers must forgo non-monetary surplus from retaining any collateral. Banks may charge a high mortgage rate due to increased default rates. We find that the interest rate of non-recourse mortgage decreases with the borrower's surplus from home ownership. Moreover, non-recourse mortgages benefit only borrowers who deem housing property as an investment asset. Hence, the transition to a non-recourse mortgage is detrimental to welfare if the borrower enjoys a large surplus from home ownership. Although the borrower privately knows how much surplus she enjoys from home ownership, a menu of non-recourse mortgage contracts may exist, yielding a separating equilibrium without information rent.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.1
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• pp.1-8
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• 2016

Permanent deformation plays a key role in performance based earthquake resistant design. In order to estimate permanent deformation after earthquake, it is essential to secure reliable response history analysis(RHA) as well as earthquake scenario. This study focuses on permanent deformation of an inverted T-type wall under earthquake. The study is composed of two separate parts. The first one is on the verification of RHA and the second one is on an effect of input earthquake motion. The former is discussed in this paper and the latter in the companion paper. The verification is conducted via geotechnical dynamic centrifuge test in prototype scale. Response of wall stem, ground motions behind the wall obtained from RHA matched pretty well with physical test performed under centrifugal acceleration of 50g. The rigorously verified RHA is used for parametric study to investigate an effect of input earthquake motion selection in the companion paper.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10a
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• pp.315-321
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• 2001

Since 1984, block-type reinforced earth wall with geogrid reinforcement has been widely used for retaining wall applications till now in Korea. The use of geogrid as a reinforcement in the reinforced earth wall is steadily increased in an amount over 1,500,000㎡ in a year However, still need exists that some problems in design and construction practices should be made to review, Therefore, this paper reviewed reasonable criteria for selection of backfills, design details considering the effect of the upper soil slope on reinforced earth wall, horizontal displacement of facing block during compaction, and the damage of geogrid reinforcements on the edge part of facing block. Finally, alternative methods of measures on those problems are proposed.

• Earthquakes and Structures
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• v.26 no.1
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• pp.1-15
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• 2024

Isolation technology has been proven effective in reducing the seismic response of superstructures, where most of the deformation is concentrated in the isolation layer. However, in cases of earthquakes with intensities surpassing the fortification level of the area, or severe near-fault earthquakes, the isolation layer may experience excessive deformation, resulting in damage to the isolation bearings or collisions with the retaining wall or surrounding buildings. In this study, a finite element model using ABAQUS is established and compared with experimental test results to deeply investigate the influence of limit devices on the isolation layer and its response to the superstructure. The findings reveal that a larger limiter stiffness and a smaller reserved gap can achieve a more effective limiting effect. Nevertheless, a smaller reserved gap and a larger limiter stiffness may result in increased response of the superstructure. Therefore, rational selection of the reserved gap and limiter stiffness is crucial to reduce the acceleration response.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.43-51
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• 2009

This paper holds three objects. The first is to analyze surveys of concerning zone and promotion department. The data were collected through an examination of construction excavated in coastal soft (marine) clay and measurements obtained during excavating construction. The second is to observe the appropriate selection and the application of support system on earth retaining wall in soft clay. Lateral deformation behavior during the excavating construction according to the differences in a soft ground pressuring degree was investigated. The third is to compare the results with those of numerical analysis. Therefore, the purpose of this study is to analyze the characteristics of lateral deformation when soft ground improvement for the expansion of infrastructure in object of study zone has been incompleted. Also, it is to identify the relationship between the degree of consolidation of soft ground and lateral deformation, in a method of displacement quantity in compliance with the numerical analysis and a quatitative analysis. In conclusion, displacement of excavated section after consolidation was fewer 60% averagely than section under consolidation.