• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1365-1369
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• 2008

A large diameter sampler (KICT-type large diameter sampler) was developed to take undisturbed samples from not only soft ground but also sandy and weathered ground. The KICT-type large diameter sampler was manufactured with the principle of triple core barrel sampling. In this study, the applicability to offshore ground sampling of the KICT-type large diameter sampler was confirmed at Inchoen Port construction site. And, in order to compare the quality of samples taken by the sampler with that of the traditional piston sampler, a series of laboratory tests were performed. From the test results, the samples taken by the KICT-type large diameter sampler showed higher quality than the traditional thin-walled tube samples.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.353-360
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• 2000

We developed large diameter sampler (we called KICT type large diameter sampler) to obtain undisturbed clay and sand samples. In-situ test carried out in the In-Chon international airport and Kim-Hae. Also we obtained undisturbed sample with a hydraulic piston sampler in the nearly site and carried out unconfined compression test, consolidation test and triaxial test. The result, unconfined compression strength, secant modules, preconsolidation pressure and undrained shear strength of samples to obtain KICT type large diameter sampler are larger than that of samples to obtain hydraulic piston sampler. But failure strains and volume changes at the consolidation of samples to obtain KICT type large diameter sampler are smaller than that of samples to obtain hydraulic piston sampler

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.291-298
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• 2001

It is very difficult to accomplish load tests of piles with large diameter constructed on the offshore area, because of requirement for large scaled loading equipment and bad testing conditions. Therefore, so far in many cases pile driving dynamic formulas have applied to quality control, and recently dynamic load test method is widely used for confirming bearing capacities of such piles. However, in cases of piles with very large diameter about 2,500mm, it is nearly impossible for regular type load test methods of piles such as static and dynamic to apply owing to very large design load. This is case studies of load tests such as modified static and dynamic load tests of piles and point load tests of rock samples for estimating rational allowable bearing capacity of very large diameter piles constructed on the marine area.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.331-336
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• 1999

A great deal of attention has been given in recent years to large diameter specimen for evaluation of soft soil characteristics, and many studies and developments of the apparatus for obtaining large diameter undisturbed soil samples are in progress attempting to minimize the disturbance of samples for precise strength and consolidation tests in the laboratory. This paper introduces a new large diameter sampler(over 300mm diameter), which can take prefectly undisturbed sampling at any depths applying a new sampling technique. By comparing the results of consolidation tests it is shown that the samples obtained by this new apparatus are of a superior quality to that of samples obtained by conventional sampler(Nx, 75mm dia.) at the same depths.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03a
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• pp.107-141
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• 2000

Large diameter piles can be defined as piles with diameter of at least 0.76 m (2.5 ft). In bridge foundation, large diameter piles have been used as pier foundations and their use has been increased greatly. In this study, static pile load tests for large diameter piles peformed in Kwangan Grande Bridge construction site were introduced. Also, various sensor installation methods for several types of piles (that is, open-ended steel pipe pile, drilled shafts and socketed pipe piles), pipe axial load measuring method, load transfer analysis method and pile load test results (pile-head load - settlement curve, and pile axial load distribution curve along the pile depth) were introduced.

• Advanced Composite Materials
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• v.16 no.3
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• pp.245-258
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• 2007

The single-modal Weibull model has been assessed on Tyranno ZMI Si-Zr-C-O fiber if a set of shape and scale parameters accurately reproduced the effect of the size of the diameter on strength. The tensile data of a single fiber have been divided into two expedient groups as 'small diameter' group and 'large diameter' group in deriving the parameters, which should be consistent if the Weibull model accurately reproduced the size effect. However, the derived Weibull parameters were inconsistent between the two groups. Thereby the authors have concluded that the parameters of the single-modal Weibull model are dependent on the fiber diameter, so that the model is inadequate to reproduce the strength size effect. On the other hand, Weibull parameters were found consistent between the two groups by excluding the data of 'large mirror zone' sample, which was defined as the sample around 10% mirror zone area of the fracture surface. What is more, the exclusion reduced the strength variance more drastically in the 'large diameter' group than in the 'small diameter' group, even though the 'large mirror zone' samples were found identical in the percentage between the two groups. The authors therefore conclude that diameter limitation to the 'small diameter' group level can lead to drastically less distributed strength values than the estimated strength through the Weibull scaling on the present Tyranno ZMI Si-Zr-C-O fiber.

• Journal of the Korean GEO-environmental Society
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• v.9 no.3
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• pp.29-34
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• 2008

A large diameter sampler was developed to take undisturbed samples from not only soft ground but also sandy and weathered ground. The large diameter sampler which was developed in Korea Institute of Construction Technology(KICT-type large diameter sampler) was manufactured based on the principle of triple core barrel sampling. A specially designed cutting device was used to cut and contain various kinds of samples in the sampler during a sampling and retrieval procedure. By adjusting the stiffness of the spring located at the top of the sampler, the distance between the cutting shoe and auger can be controlled in accordance with the ground condition. In order to investigate the applicability of the developed sampler and compare the quality of the samples taken by the sampler with that by the traditional thin-walled tube sampler, samples were taken at various sites according to the ground condition. And a series of laboratory tests such as the unconfined compress ion test, triaxial compression test, oedometer test, large diameter Rowe cell consolidation test (D: 150 mm) were performed. The test results showed that the samples by the KICT-type large diameter sampler show higher quality than the samples by the thin-walled tube sampler. And the validity and applicability of the developed KICT-type large diameter sampler was confirmed accordingly.

• Journal of the Korean institute of surface engineering
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• v.51 no.1
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• pp.27-33
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• 2018

In the present work, we demonstrate the feasibility to form large inner diameter $TiO_2$ nanotubes by anodization of Ti in a HF/ethylene glycol electrolyte. In order to achieve the large inner diameter $TiO_2$ nanotubes, optimization of the anodization condition is required. We discover the key factors in the formation of large inner diameter $TiO_2$ nanotubes are concentration of water in the electrolyte, anodization temperatures, and high-applied potential. Under optimum conditions, the inner diameters of $TiO_2$ nanotubes are 379 nm. The results are approximately 3 folders larger than the general case.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.486-493
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• 2006

This paper deals with the procedure and the results on the dynamic loading tests of two large diameter - long drilled shafts (diameter=2.0m, length=75m) which were embedded into weathered rocks through thick soft marine clays and sandy gravels. Prior to the real dynamic loading test, the numerical simulation for the test procedure was performed to check the structural stability of the main pile body using equivalent static elastic analysis and the application of the hammer system using WEAP (Wave Equation Analysis of Pile Driving). Through these preliminary analyses the dynamic loading tests on large diameter - long drilled shafts have been successfully achieved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.482-487
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• 2014

The purpose of this study (I) is to provide a new methodology for evaluating deterioration of buried pipe networks for the large-diameter old pipe improvement project currently performed by K-water. To develop a new assessment model for large-diameter pipe deterioration, this study has investigated the three representative methods for the pipe deterioration assessment such as evaluation methods 1995 and 2002, and the state evaluation method through literature reviews. The ten assessment factors were selected by considering large-diameter pipe characteristics as well as common factors with high priority in the three methods. Also, the weighting of the factors was estimated by a regression equation from experiments and analysis on domestic large-diameter pipelines and expert survey data. It is expected that the new assessment model developed by analysing the existing three models is more reliable to assess the deterioration of large-diameter pipe networks.