• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.191-196
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• 1994

This study is designed for analyzing the mechanical properties of cement mortar with kind of water, sludge content for the water, mixing proportion and open time of recycling water. And this study is aimed for presenting the reference data in practical use. For the results of this study, the flow properties of fresh mortar and the strength of compresive of hardened mortar is increased until the sludge content 4.5~6.0, but is decreased after the sludge content of that.

• Journal of Environmental Science International
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• v.13 no.2
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• pp.143-148
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• 2004

In this paper, the properties of inter - locking block using fly ash are discussed in order to provide economical advantages and improve quality, and protect environment and recycle resources. Fly ash is the by-product of coal in thermal power plant. The experimental parameters are fly ash content, the amount of AE water - reducing agent and mixing proportion of cement mortar. According to the experimental results, the improvement of quality in the side of strength, absorption ratio and freeze - thaw resistance for manufacturing inter -locking block and the curtailment of cost can be achieved in case of 15% of fly ash and 0.3% of AE water- reducing agent are mixed into mortar mixture of 1 :6(C:S).

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.317-322
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• 2001

This paper investigates the influence of fine aggregates on bleeding of concrete. According to test results, as water content decreases, crushed sand content increases, fluidity shows decline tendency. As for aggregates kinds, concrete using sea sand shows most fluidity loss among the tested results. Compressive strength gains highly when crushed sand is used. As for bleeding of concrete, bleeding shows decline tendency because of increasing in powder content and filling effect of voids. Bleeding amount is in a decreasing order of magnitude for concretes made with the following aggregates: sea sand, river sand, and crushed sand. Accordingly, crushed sand mixed with river sand and sea sand with certain proportion enable to reduce bleeding and enhance strength.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.78-83
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• 1995

In lTI2ny countries, a considemble amount of demolition waste IS generated and concrete forms a signiftcallt proportion of the waste. The neceSSity for the lIse of recycled aggregate in concrete arises due to the following reasons : (1) diminishing supplies of natuml aggregates; (2) securing ample supply of concrete aggregates to the construction industry; (3) dirninisrl! ng dumping area within the utban limits; and (4) avoid,ing danger to marine life by limiting the indiscriminate dumping of highly alkaline nature of concrete in the sea. It is the purpose of thiS report to improve the quality of recycled aggregate concrete and to put to practical use of such concrete.

• Journal of Environmental Impact Assessment
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• v.12 no.4
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• pp.303-313
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• 2003

This study was carried out to survey the high ozone episode of summertime in Busan. The selected day was July 18, 1999 and August 24, 2001 which recorded exceed to 12ppb/hr at 3 station in Busan simultaneously. In case July 18, 1999, thick cloud and variable wind made weak ozone concentration during morning hour. And increase of ozone concentration by revolution of mixed layer for morning hour did not occur in this case study day. Photochemical reaction by strong radiation after 1100LST made sharp increase rate of ozone concentration(50ppb/hr). In case August 24, 2001, the meteorological condition of this day was not general wind with gradient force, very clear day with less cloud amount, high insolation and sunshine. Dongsamdong, Beomcheondong, Daeyeondong, and Sinpyeongdong had double peak which twice maximum concentration in the early afternoon and late afternoon. Ozone concentration of this day was in inverse proportion to Nitrogen oxide strongly. Ozone concentration exceed to 60ppb/hr occurred at 1400LST, continued to 2300LST.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.29-32
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• 2006

The techniques related to ultra-high strength concrete(UHSC) became the key issue in recent days since requirements of the high-rise building which story is over than 100 gradually increases. Therefore, for the development of 150MPa UHSC this research is generally categorized by 4 parts: development of pre-mixed binders, evaluation for the fire performance of coarse aggregate, optimization of the mixture proportion, and mock-up test. Finally, based on the optimized mixture and its laboratory tests, mock-up test for wall and column specimens were carried out to simulate and evaluate the UHSC in real situation. The mechanical properties of core specimens were compared with the cylinder specimens made in laboratory. For instance, it showed the reasonable the results that the strength at the age of 91 days is 183MPa.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.33-36
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• 1998

Generally, the base concrete for manufacturing the flowing concrete has to increase the fine aggregate content or adjust the fines content prevent the concrete from segeration, However, it may not only increase the cost, but cause the inconvenience in production of base concrete. In this paper, the experiments is performed on the superplasticizer which is used for base concrete by mixing viscosity agents and AE admixtures. According to the results, it shows that it is possible to manufacture a flowing, non segregation, high durability and economical concrete in the field without increasing the fine aggregate content of base concrete, when the superplasticizer are mixed with viscosity agents and AE admixtures in an appropriate proportion.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.297-298
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• 2010

This study was investigates to the lightweight foamed concrete are uses by foamed agent to hydrogen peroxide($H_2O_2$). and then, lightweight foamed to improve the physical characteristics were mixed. mixes to type of admixture/level by changes/character to investigates, It is a purpose to look up admixture and mix proportion to be suitable in order to improve lightweight foamed concrete.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.10a
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• pp.248.1-248
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• 1979

Sixteen temperature-sensitive mutants of Autographa californica nuclear polyhedrosis virus were isolated. Several interesting phenotypes were observed. A large proportion of the mutants were un-able to form polyhedral occlusion bodies at the nonpermissive temperature (32.5C). At 32.5C, one mutant formed plaques in which the cells lacked polyhedra. Another mutant type was defective in the production of progeny extracellular nonoccluded virus and produced a plaque consisting of only a single cell containing polyhedra at 32.5C. One mutant was defective in plaque formation, progeny nonocluded virus formation, and polyhedra formation at 32.5C. Several mutants produced nonocluded virus but failed to produce plaques or polyhedra at 32.5C. Other phenotypes were also distinguished. Complementation analyses, performed by either measuring the increase in extracellular non-ocludedvirus formation or by oberving polyhedra formation in mixed infections at 32.5C, indicated the presence of 15 complementation groups. A high frequency of recombination was observed. Four of the mutants were found to be host dependent in their temperature sensitivity for polyhedra formation.

• Phonetics and Speech Sciences
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• v.8 no.1
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• pp.45-51
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• 2016

This study examined the deletion of onset consonant in the word-internal structure in spontaneous Seoul Korean speech. It used the dataset of speakers in their 20s extracted from the Korean Corpus of Spontaneous Speech (Yun et al., 2015). The proportion of deletion of word-internal onset consonants was analyzed using the linear mixed-effects regression model. The factors that promoted the deletion of onsets were primarily the types of consonants and their phonetic contexts. The results showed that onset deletion was more likely to occur for a lenis velar stop [k] than the other consonants, and in the phonetic contexts, when the preceding vowel was a low central vowel [a]. Moreover, some speakers tended to more frequently delete onset consonants (e.g., [k] and [n]) than other speakers, which reflected individual differences. This study implies that word-internal onsets undergo a process of gradient reduction within individuals' articulatory strategies.