• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.4
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• pp.333-342
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• 2022

This paper has theoretically and practically reviewed the ISO (International Standard Organization) 17123-8 standard not only to raise the appropriateness for introducing performance criteria of GNSS (Global Navigation Satellite Systems) surveying equipment based on RTK (Real-Time Kinematic) accuracy but also to derive its proper test procedure by introducing the international standard. Field experiments have been performed to appreciate the GNSS-RTK accuracy of five selected receivers via the full testing procedure of the ISO standard, which statistically compares the so-called experimental standard deviations with themselves and with the reference accuracy. A series of statistical tests have revealed that the RTK accuracy of the same class receivers is not identical, whereas that of the different classes can be equivalent. Such a result evidences the urgency of adopting an RTK accuracy-based specification of the GNSS equipment to the performance standard, currently referenced to the static observation technique only. It is believed that this transition helps the maximization of a new generation of cost-effective receivers to legal surveying applications. Finally, this study proposes the ISO full test, comparing an experimental standard deviation with its referenced value, for a potential field verification procedure of the new performance standard.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.283-290
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• 2008

The repair technique using surface impregnation of reactive compound is so effective for deteriorated concrete structures that many researches are recently focused on these works. Particularly, inorganic impregnant is regarded as ecofriendly material because there is no air-pollution during manufacturing process as well as field coating works. Furthermore, The delamination between old concrete and impregnated surface does not occur, resulting from different material characteristics. In order to evaluate the durability performance of surface-impregnated concrete, durability evaluation through the long-term exposure tests is significant, however, experiments are usually limited to the temporary and qualitative laboratorial scope. In this study, durability characteristics for inorganic and organic/inorganic impregnated concrete specimens are evaluated through longterm chloride exposure test. The specimens with 21MPa and 34MPa strength have been prepared and exposed to chloride attack in the atmospheric, tidal, and submerged conditions. Evaluation for compressive strength, chloride penetration, and electrical potential (half cell potential) for steel corrosion are performed for the specimens exposed for 2 years. From the results, no distinct strength gaining is observed but the resistance to chloride penetration and steel corrosion is evaluated to be improved through surface impregnation. The more improved resistance to chloride attack is measured in the inorganic impregnated concrete and the results from atmospheric condition show more improved resistance to chloride attack than those from submerged and tidal condition.

• Tunnel and Underground Space
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• v.22 no.2
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• pp.130-143
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• 2012

Cablebolts used to be employed as auxiliary supports where long or high capacity bolts are needed, but become competitive by the improvements in supportability and easiness in handling. Based on the test results obtained from various researches, the performance of the cablebolts was analyzed numerically while varying lengths and fixing conditions. The supporting effecte is assessed by monitoring displacements and stress taken place in shotcrete. When cablebolts are grouted without being tensioned, supporting effect was not as good as that of rockbolts. But, their supportability was good enough to substitute rockbolts if tensioned properly. Post grouting right after tensioning of the cablebolts shows reduction in supportability, but long term stability could be achieved without losing supportability if grouted when the bolt is far enough from the face. Further study is necessary including laboratory and in-situ tests under various conditions to use cablebolts as main support in tunnels.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.577-580
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• 2008

This paper was discussed about in-site application of heavyweight(or high density) concrete. Heavyweight concrete was placed with the method of conventional. Placement of conventionally mixed heavyweight concrete is subject to the same considerations of quality control as normal density concrete, except that it is far more susceptible to variations in quality due to improper handling. It is particularly subject to segregation during placement. Segregation of heavyweight concrete results not only in variation of strength but, far more importantly, in variation in density that are intolerable for work this type, since this adversely affects shielding properties. Heavyweight concrete materials and heavyweight concrete should be sampled and tested prior to and during construction to insure conformance with applicable standards and specifications.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.220-228
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• 2010

A steel wire-integrated deck plate that welds integrated triangle truss steel wires on a galvanized steel sheet is developed to reduce construction costs of a slab or formwork such as shores and supports, and it is already widely applied in many construction fields. This study selected upper and lower steel wires, lattice steel wires, span, and cutting methods of ends as variables, and conducted an experimental test by manufacturing a total of 32 full scale test bodies. According to the result, changes in final destruction types of the test bodies and cutting methods of ends didn't affect structural performance of test bodies, and for a 3.2m-span test body, there was no big problems in using ${\Phi}4.5$ of lattice steel wires.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.16-27
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• 2003

For the last decade, some 400 small and large oil spill accidents have occurred every year. Such accident blow a serious damage to the marine resource and ecosystem, which can't be estimated in terms of economic and environmental losses. The physical/chemical methods used currently may be effective at the initial stage of accidents, but they can't serve to remove the spilled oil completely. Moreover, the dispersant may lead to a secondary contamination detrimental to the lives inhabiting wet lands, beaches and tidal zone. Thus, a new decomposing technology Is required for the environmentally sensitive areas. Bioremediation is the active use of biological techniques to mitigate the consequences of a spill using biological processes and refers both of stimulation of pollutant biodegradation and/or to enhance ecosystem recovery Bioremediation is an economically attractive method for the clean-up of oil-contaminated area. Bioremediation has been demonstrated to be an effective oil spill countermeasure for use in cobble, sand beach, salt marsh, and mud flat environment.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.103-111
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• 2010

This research aims to make a contribution to the development of waterproofing technique for rooftops by analyzing and understanding the problems of the currently used waterproofing method and their causes. To do this, this research developed an eco-friendly waterproofing method that supplements the weaknesses of the conventionally used method by analyzing the problems of leakage resulting from design and construction work to diminish leakage, improving the quality of construction work, reducing labor required and the period of construction, and improving environment alconditions. The characteristics of the newly developed method are comparatively analyzed with the convention alpractices, and are evaluated on the site.

• Journal of the Korean Geotechnical Society
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• v.25 no.7
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• pp.55-64
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• 2009

In this study, improved test methods, which consider the real site test conditions, were suggested to measure for geosynthetics chemical resistance. For this purpose index and performance tests were done to specify and regulate the test method most approaching to the installation condition and accelerated model by Arrhenius equation was applied to interpretate the experimental data. Through the analysis and comparison of the overall experimental results, we could suggest the possibility and setup of the advanced chemical resistance test method for geosynthetics fitting to the field installation conditions.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.945-948
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• 2008

Fire resistance is a measure of the ability of building element to resist a fire. For concrete columns, the fire resistance depends on many factors, including strength, density, and moisture content of concrete, fire intensity, column size and shape, reinforcement detail, loading condition, and aggregate type etc. However, it is well-known that the high strength concrete (HSC) is more susceptible to spalling than normal strength concrete (NSC) and the behaviour of HSC column exposed to fire is significantly affected by the spalling. Recently, as one of the measures to reduce the spalling of HSC, incorporating polypropylene(PP) fiber has been investigated and successfully used in construction fields. However, the establishment of assessment method on the fire resistance of HSC column is very important as well as the improvement of fire performance of HSC. In this study, the variations on the fire resistance of HSC column with assessment methods was studied for the columns controlled the concrete spalling by PP fiber.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.552-559
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• 2023

The purpose of this study is to evaluate the crack reduction performance of blast furnace slag concrete mixed with expansive and swelling admixtures. As a basic performance test, various ingredients such as blast furnace slag fine powder (BFS), calcium sulfoaluminate (CSA), bentonite, and hydroxypropyl methyl cellulose (HPMC) were used, and the results showed that bentonite showed superior performance compared to HPMC. Afterwards, a MOCK-UP test was conducted to evaluate cracking and drying shrinkage according to the mixing ratio. As a result, when bentonite and a small amount of calcium phosphate were added, drying shrinkage was reduced and cracking was reduced. In particular, a cement mixture consisting of 30 % BFS, 1 % bentonite, and 1 % calcium phosphate showed optimal crack-free performance. It is believed that BFS concrete will contribute to compensating for shrinkage through continuous expansion activity and can be used for field applications.