• Genomics & Informatics
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• v.10 no.3
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• pp.133-144
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• 2012

Genetic admixture in human, the result of inter-marriage among people from different well-differentiated populations, has been extensively studied in the New World, where European colonization brought contact between peoples of Europe, Africa, and Asia and the Amerindian populations. In Asia, genetic admixing has been also prevalent among previously separated human populations. However, studies on admixed populations in Asia have been largely underrepresented in similar efforts in the New World. Here, I will provide an overview of population genomic studies that have been published to date on human admixture in Asia, focusing on population structure and population history.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.361-364
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• 2005

This study reports the properties of high early strength of concrete using PC admixture. To apply these data to construction site, we did the lab tests and mock-up test. The target of this study is to accomplish early strength of concrete(5 MPa/18 hr), and we tested 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. 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 can accomplish the economical construction.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.317-320
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• 2004

The setting time is very important factor affecting the quality of tunnel lining and reinforcement of sloped slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of a cement accelerating admixture was performed. Six types of measuring methods were checked and a proper measuring method of the admixture were proposed as fellows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate the properties of it, an admixture usage of $5\%$ (ratio of cement weight) is recommended.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.144-145
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• 2014

Nowadays, as to increased the workability of the press concrete and decrease the cracking, the fiber-reinforced admixture has been widely used. As the low adhesion force between the paste and fiber-reinforced admixture, it was considered as could not be used in the structure. Even more, as the loss of flowability and the exposure of the fiber, further study is needed. In this study, as the different environment and position of the building, the dosages of the fiber-reinforced admixture has also been changed. The fundamental properties and cracking of fiber-reinforced concrete have been tested.

• Journal of the Korea Institute of Building Construction
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• v.7 no.4
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• pp.117-124
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• 2007

Focused on the material-related aspect for enhancing the durability of concrete, the present study analyzed the effect of glycol ether admixture, which is a chemical admixture that can compact the structure of concrete by entraining air inside the concrete, on the basic physical properties and durability characteristic of the concrete. In analyzing the results of experiment, we examined the basic physical properties and durability characteristic of concrete according to addition rate based on OPC and selected the optimal addition rate. In addition, with the optimal addition rate, we added glycol ether admixture to concrete, which contained fly ash used as binder and high-performance water reducing agent for reducing the unit quantity, and examined changes in the characteristics of the concrete. According to the result, the optimal addition rate of glycol ether admixture was 3% of the unit quantity of cement, and the addition of binder and chemical admixture did not have a significant effect on unhardened concrete but reduced the air content. In addition, concrete showed resistance performance of around 30% to carbonation and around 40% to drying shrinkage. In addition, as for resistance to freezing and thawing, the relative dynamic modulus of elasticity was over around 85% through atmospheric curing. These performances prove the effect.

• Journal of the Korea Institute of Building Construction
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• v.7 no.2 s.24
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• pp.59-65
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• 2007

Recently, due to the increase of high-rise buildings construction, many researches for making harden of concrete earlier and remove of forms faster are being performed to reduce construction period. In this study, we compared and analysed the early strength properties of mortar according to the kinds and replacement ratio of mineral admixture to select the kinds and replacement ratio of mineral admixture of high early strength concrete. For this purpose, mortar mixtures according to the kinds(FA, MK, ZR, BFS, DM) and replacement ratio(0, 2, 4% by volume of sand) of mineral admixture were selected. From our test data, early-age compressive strength decreased in accordance with the increase of replacement ratio of fly-ash(FA) & blast furnace slag powder(BSF) and, in case of addition admixture, early-age compressive strength of with containing 4% appeared higher compared with containing 2%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1452-1457
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• 2011

Strength properties of cement mortar was carried out silica fume(SF) and Titanium Dioxide($TIO_2$) by nano admixture of dry process and wet process. Experimental parameters were Nano admixture as the dry process and wet process 5, 10, 15 or 20%. As a result, strength properties of cement mortar by silica fume(SF) and Titanium Dioxide($TIO_2$) were similar and in a comparative experiment of the dry process and wet process Nano admixture using wet process Nano admixture showed a greater strength properties.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.669-674
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• 2001

Electric Arc Furnace Dust (EAF Dust) Is residual dust produced during the manufacturing of metal products from heavily heated electric arc furnace. Many researches have focused on recycling and reusing EAF Dust for industrial and construction purposes. However, most of these researches were aimed at obtaining useful heavy metal powders by treating toxic metallic materials in EAF Dust. Also, few researches dealt with using EAF Dust as admixture in concrete mixture (i.e., slag dust). In this study, EAF Dust is used as admixture in concrete mixture content considering economical feasibility and construction applicability. The concrete specimens mixed with EAF Dust is then tested in compression and tension to study its strength and ductility as well as its failure mechanism. The compression and tension (by split cylinder test) test results are compared to the results from the specimens without EAF Dust to understand the chemical stability and mechanical characteristic of concrete specimens with EAF Dust. For the experiment, 6 types of admixture added concrete were studied: ⑴Combination of EAF Dust and blast-furnace slag in 1 to 1 ratio, ⑵Combination of EAF Dust and blast-furnace slag in 1 to 2 ratio, ⑶EAF Dust only, ⑷blast-furnace slag only, ⑸fly ash only, and ⑹no admixture. The experimental results show that the strength of EAF Dust added specimen has lower early age strength but higher 28 day strength when compared to other specimens. Also, the Elastic Modulus of EAF Dust is higher(28 days) than other specimens. The study results prove that EAF Dust can be used as an effective admixture in concrete for specific usages.

• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.127-133
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• 2003

Carbonation and drying shrinkage are very important properties of concrete, that can cause concrete to lower its capacity and spall. But the research on them in high strength concrete is very poor. In this study, to estimate influences of W/B, the kind of admixture, the replacement ratio of admixture, fineness of blast furnace and etc. on drying shrinkage and carbonation, we make experiment with 3 levels(28, 35, 55%) of W/B, 3 kinds(blast-furnace slag, fly-ash, silica-fume) of admixture, 3 levels of the replacement ratio, 3 levels(4000, 6000, 8000cm2/g) of fineness of blast-furnace slag and 2 kinds of curing condition. As the results, compressive strength of concrete was decreased, as W/C was increased and the replacement ratio of admixture was increased. Drying shrinkage was increased, as W/B was higher, the replacement ratio of admixture was increased and fineness of blast-furnace slag was decreased. And carbonation was increased, as W/B ratio was higher, the replacement ratio of admixture was increased.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.1
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• pp.85-92
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• 2000

Recently. there has been steadily applied in high-performance concrete using powder type admixture in construction field. It has been reported that high-performance concrete is likely to cause the spalling by fire more seriously due to the dense microstructure. In this paper, spalling properties of high-performance concrete with the kinds of admixture and polypropylene(PP) fiber contents are presented. According to the experimental results concrete contained no PP fiber take place in the form of the surface spalling, regardless of admixture. Concrete contained more than 0.05% of PP fiber and admixture do not take place the spalling, however the concrete using silica fume do spalling. Concrete using blast furnace slag have good performance in spalling resistance. It is found that residual compressive strength has 60~70% of its original strength when spalling do not occur. Although specimens after exposed at high temperature are cured at water for 28days, they do not recover their original strength.