• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.217-224
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• 2007

This study reports the properties of high early strength & durability of concrete using PC admixture. To apply these data to construction site, we did the lab tests. The target of this study is to accomplish early strength of concrete (5.0 Mpa/18 hr), and we did the durability tests such as length change test, chloride ion penetration test, fleeting and thawing test, adiabatic test, etc. And we tested the porperties of concrete by the different factors, such as the type of admixtures, curing temperature, the amount of binder, etc. Through the test of concrete using the different type of admixture, PC type was more excellent than PNS type admixture. As a result, we made a concrete of high early strength concrete, and excellent durable concrete. According to these tests, we concluded that we can apply this type of PC admixture to the civil & construction site, and we can reduce the term of works and finally we will accomplish the economical construction.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.33-40
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• 2002

Vacuum concrete manufactured by vacuuming and decompressing fresh concrete. It is known to have improvement on abrasion and strength by making a structural confinement through elimination of internal gap. It has been implemented on buildings floors, concrete dam, etc. in developed countries. This study was aimed to monitor changes in physical characteristics such as strength and slump of concrete influenced by changes of vacuum, decompression level and combination condition during concrete manufacturing process. The results are as follows: It is indicated that decompressed concrete shoved increase in unit weight and compressive strength by compact compression phenomenon influenced by decrease in internal gap caused by diminishing oxygen. However, continuous research is necessary to resolve problems on construction, design and durability.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.261-267
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• 2015

To develop high-strength high-volume ground granulated blast-furnace slag (GGBFS) concrete, this study investigated the characteristics of strength development and durability of concrete with the water-to-binder ratio of 23% and the GGBFS replacement ratio of up to 65%. The results show that the compressive strength of GGBFS blended concrete is lower than that of ordinary Portland cement (OPC) concrete up to 3-day age, but the becomes higher after 7-day age. Together with strength increase, the pore structure becomes tighter, and thus the resistance to chloride ion penetration increases. Therefore, the GGBFS blended concrete has high resistance to freezing and thawing without additional air-entraining, and high resistance to carbonation despite low amount of calcium hydroxide ($Ca(OH)_2$). On the other hand, if silica fume (SF) is blended with GGBFS, the strength becomes lower than that of the concrete blended with GGBFS only, and the resistance to chloride ion penetration deceases. Therefore, it needs further studies on the reaction of SF in high-strength high-volume GGBFS concrete.

• Composites Research
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• v.27 no.3
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• pp.109-114
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• 2014

Manufacture of nancomposites has simple process for developing nanocomposites due to the increasing applications using nanofillers. This work studied nanofiller coated glass fiber for reinforcing material with good wetting and conductivity and the morphology of nanofiller coated glass fiber was analyzed by FE-SEM. The durability of reinforced glass fiber was investigated with different shapes of nanofillers using sonication rinsing method. Fatigue test was performed to evaluate the adhesion of reinforcing interface and stability of nanofiller coating layer for single fiber reinforced composites. Apparent modulus and conductivity of nanofiller coating layer were evaluated to realize multifunctional of nanocomposites. Fiber type of nanofiller was better than plate type due to better cohesion between fiber and nanofillers. At last, the stability of fiber type nanofiller of coating layer has better durability and conductivity than plate type case.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.425-428
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• 2008

To use lightweight aggregate concrete with the structural material, it was need to evaluate property of mechanic and drying shrinkage and creep of the lightweight aggregate concrete, but these weren't. So the purpose of this study which it sees follows the mechanical property of the eco lightweight aggregate concrete according to the water binder ration in the high strength concrete. Eco lightweight aggregate was made with clay and crushed rock in this study. To make experiment, water binder ratio was divided 35% and 39%. And the fresh concrete properties were that slump flow was 500${\pm}$50mm, air contents was 2.0${\pm}$1.0%. It evaluated the hold a drying shrinkage and the creep the effect, it analyzed quality and reliability of the eco lightweight aggregate concrete.

• Transactions of the KSME C: Technology and Education
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• v.5 no.2
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• pp.89-95
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• 2017

LCD robot vertical frame lets a arm assembly with glass substrate move up and down, so it must have high stiffness and strength. We applied new manufacturing process by using design optimization process such as topology and size optimization in order to satisfy the request of high stiffness and light weight. The proposed model should be evaluated for endurance strength. Therefore fatigue assessment for weak point of aluminum welding area of vertical frame studied with hot spot stress approach. And the actual stress measuring from test was compared and evaluated with the dynamic stress calculated from multi-body dynamics considering flexible body.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.297-302
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• 2019

A-pillar is closely related to safety for the purpose of protecting the bodies of passengers by mitigating the impact that may be caused by the vehicle being overturned while driving. Therefore, the A-pillar should protect these parts from a variety of dynamic loads. This study result is thought to contribute for the strength and durability of A-pillar by designing two types of parts before making this product and analyzing the product which thickness is adjusted for the light weight of vehicle. If this study result is practically applied to the parts of A-pillar in a car, it is considered that the damage can be protected by the durability verification of design. By utilizing the data of analysis and design on the strength and durability of automotive A-pillar in this study, the esthetic sense can be given by being grafted onto the real automotive part.

• Ecology and Resilient Infrastructure
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• v.3 no.2
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• pp.117-125
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• 2016

Current cities encounter various types of water problems due to rapid urbanization and climate change. The increasing significance of urban water problems calls for the establishment of resilient alternatives to prevent and minimize social loss that results from these phenomena. As a background research for establishing resilient infrastructures for the mitigation of urban water problems, we evaluated the robustness of structural alternatives for urban flood as a representative case. Combining the robustness index (RI) and the cost index (CI), we suggested the robustness-cost index (RCI) as an indicator of the robustness of structural alternatives, and applied the index to assess the existing infrastructures and structural alternatives (i.e., sewer network expansion, additional storage tank construction, and green roof construction) at a site prone to floods located around Gangnam-station, Seoul, Korea. At a rainfall intensity frequency range of 2 to 20 years, the usage of a storage tank and a green roof showed relatively high RCI value, with a variation of an alternative showing greater RCI between the two depending on the size of design rainfall. For a rainfall intensity frequency of 30 years, installing a storage tank with some green roofing was the most resilient alternative based on the RCI value. We proposed strategies for establishing resilient infrastructures for the mitigation of urban floods by evaluating the robustness of existing infrastructures and selecting optimal structural alternatives with the consideration of scales of design disaster.

• Journal of the Korean GEO-environmental Society
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• v.12 no.7
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• pp.49-56
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• 2011

Recently, the ground injection method using water glass as one of the components of the main resources and the products of the construction has some basic problems for permanent reinforcement of foundation and stopping leakage of water because it has some serious problems such as durability reduction, compression strength reduction and eluviation. This study was to evaluate the environmental impact and durability of the developed friendliness of Natural and Durable Stabilizer(NDS) of inorganic injection and Space Grouting Roket(SGR) with typical water glass type material. Two materials, NDS and SGR, were compared with each other by unconfined compressive strength test, fish poison test, durability test and triaxial permeability test. The results of the durability test indicated that the 28-day strength of the NDS was 1.5 times higher than that of the SGR. The fish poison test proved that the survival rate in the SGR and NDS is 50~70%, and 100%, respectively. Therefore, the NDS has higher survival rate than that of the existing SGR. The NDS will be considered by an environmentally friendly product and moreover it has a few problems for soil and groundwater pollution.

• Magazine of the Korea Concrete Institute
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• v.13 no.4
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• pp.70-75
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• 2001