• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.989-992
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• 2008

In this paper, we are presenting a case that integrates ultra high strength concrete(150MPa) with surface-exposed concrete. Ahead of the field application, we carried out laboratory experiment and B/P Test for a basic property of concrete(slump flow, air content, 50cm flow time, elapse time change and compression strength) and productivity. The next, we conducted Mock-up Test using simulation specimen to evaluate infilling, surface-finishing and hydration heat of concrete. We had satisfactory results for a basic property and hydration heat of concrete. However at the time of field application, it was occurred rupture of formwork because of high lateral pressure of concrete, and then formwork was reinforced and case-in-place time was adjusted. And regardless of low and high frequency vibration, it occurred to surface-pockmark. In case that applies ultra high strength concrete to surface-exposed concrete, we estimate that it is important of systematic management and improvement of construction.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1233-1242
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• 2008

The hydration effect on the intrinsic magnetism of natural salmon double-strand DNA was explored using electron magnetic resonance (EMR) spectroscopy and superconducting quantum interference device (SQUID) magnetic measurements. We learned from this study that the magnetic properties of DNA are roughly classified into two distinct groups depending on their water content: One group is of higher water content in the range of 2.6-24 water molecules per nucleotide (wpn), where all the EMR parameters and SQUID susceptibilities are dominated by spin species experiencing quasi one-dimensional diffusive motion and are independent of the water content. The other group is of lower water content in the range of 1.4-0.5 wpn. In this group, the magnetic properties are most probably dominated by cyclotron motion of spin species along the helical π -way, which is possible when the momentum scattering time (${\tau}_k$) is long enough not only to satisfy the cyclotron resonance condition (${\omega}_c{\tau}_k$ > 1) but also to induce a constructive interference between the neighboring double helices. The same effect is reflected in the S-shaped magnetization-magnetic field strength (M-H) curves superimposed with the linear background obtained by SQUID measurements, which leads to larger susceptibilities at 1000 G when compared with the values at 10,000 G. In particular, we propose that the spin-orbital coupling and Faraday's mutual inductive effect can be utilized to interpret the dimensional crossover of spin motions from quasi 1D in the hydrate state to 3D in the dry state of dsDNA.

• Applied Biological Chemistry
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• v.33 no.1
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• pp.18-23
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• 1990

Seven varieties of soybeans(Paldal, Danyeob, Jangbaek, Baegun, Jangyeob and 2 cultivars of Local 1 and Local 2) were investigated to compare the water uptake properties and volume changes during soaking in water. The hydration properties showed that the equilibrated weight increase ratio decreased as the soaking temperature raised to higher than $40^{\circ}C$, while the initial water uptake rate increased upto $80^{\circ}C$. The increase in hydration showed a linear relationship with the square root of the soaking time at $4^{\circ}{\sim}60^{\circ}C$. Local 1 was the highest in water uptake rate constant while Local 2 was the lowest. The activation energy calculated was in the range of $3,246{\sim}4,694\;cal/mole$. The Jangbaek and Local 1 were the highest and the Paldal was the lowest in the rate of volume increase. The activation energy for volume increase was in the range of $3,310{\sim}4,190\;cal/mole$. The z-values calculated from volume change was a little higher than those obtained from weight change.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.1
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• pp.27-32
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• 2014

This study analyzed the fundamental characteristics of concrete according to a ternary system mixing in order to reduce hydration heat of mass concrete and to improve early age strength. The results are as follows. The fluidity of unconsolidated concrete satisfied the target scope regardless of the binder conditions. When the replacement ratio between FA and BS increased, the slump of low heat-A mix and low heat-B mix increased, and air content was not affected by the change of binders. As for setting time, low heat cement mix had the fastest regardless of W/B, and high early strength low heat mix achieved 6 hours' reduction compared with low heat-B mix at initial set, and 12 hours' reduction at the final set respectively. As for the simple hydration heat, the low mix peak temperature was the highest and low heat-B mix had the lowest temperature. And high early strength low heat mix was similar with that of low heat-B. The compressive strength of hardened concrete had similar strength scope in all mixes except for low heat-B mix at early ages, and had unexceptionally similar one without huge differences at long-term ages.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.669-672
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• 2008

To analyze possibility for high performance concrete that massively displaces blast furnace slag, this study analyzed the characteristics of concrete by blast furnace slag displacement rate changes, and the results are summarized as follows. Firstly, as for fresh concrete characteristics, flow tended to increase and air amount decreased with increase in blast furnace slag displacement rate, and settling time was shown delayed. As for hardened concrete characteristics, in conditions where blast furnace slag displacement rate increased up to 50%, the compressive strength decreased below OPC at early age, however at age 28 days, its level was no less than that of OPC, and as for temperature rise by simple insulation, it decreased as displacement rate increased at early stage of hydration, but in the latter stage, hydration progress slowed down and hydration heat increased.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.63-72
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• 2017

This research investigated the effect of solar radiation on the temperature distribution in concrete mat foundation. Zhang and Huang Model was utilized to estimate solar radiation heat at a given date and time. A one-dimensional finite element formula was derived with the fundamental laws of heat transfer and Galerkin method. Based on the formula, a one dimensional finite element analysis code was developed using MATLAB. Hydration heat analysis of mat foundation were conducted using the developed code. It was found that the solar radiation reduced the maximum temperature difference in mat foundation, and this temperature difference reduction was more prominent in case of summer season cast, a higher initial concrete temperature, and a thicker mat foundation depth. The research recommended that the solar radiation should be considered in hydration heat analysis of concrete mat foundation so as not to overestimate the maximum temperature difference in mat foundation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.112-119
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• 2022

Recently, as carbon neutrality has been important factor in the construction industry, many studies have been conducted on the high-volume fly ash concrete. High volume fly ash concrete(HVFC) is usually made by replacing more than 50% of cement with fly ash. However, HVFC has a disadvantage of low compressive strength in early age. To overcome this shortcoming of HVFC, improve this, interest in techonolgy using nanomaterials is increasing. Nano silica is expected to improve the early age strength of HVFC as a pozzolanic material. This study investigated the effect of nano silica on the early hydration reaction and microstructure of HVFC. The early hydration reaction of HFVC was analyzed through setting time, isothermal calorimeter, compressive strength and thermal weight analysis. In addition, the microstructure of HVFC was measured by mercury intrusion porosimetry. From the test results, it was confirmed that nano silica increased the early age strength and improve the microstructure of HVFC.

• Korean journal of food and cookery science
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• v.22 no.3 s.93
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• pp.337-345
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• 2006

The properties of various grains used for the solid-state cultivation of basidiomycetes were examined. The hydration time with cold water was 10 hours for malt soybean. The required hydration time for Job's tears, barley and wheat was 4, 6 and 12 hours, respectively, but the final moisture content ranged from 30 to 48 %, which was much less than the optimum moisture content for mycelial growth. For the mass cultivation of mycelia, the hydrated grains with cold water were placed in plastic bottles. The mycelial growth ra in e bottled grains was high in the early stage with inoculation of homogenized mycelium. The mycelium activity was maintained by adding sterilized water in the middle of the cultivation period. Jupjang underwent sensory evaluation to examine the possibility of utilizing basidiomycetes in functional foods. The grains fermented with Ganoderma lucidum was the best for Jupjang. The combination of malt soybean and Job's tears was the best for Jupjang. The acceptability of Jupjang was improved during the period of aging time.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.349-352
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• 2010

The production process of cellulosic ethanol from rice straw using acidic saccharification was studied in this experimental work. The hydration by ultrasonic energy and the acidic saccharification using 10~30 wt% of $H_2SO_4$ were performed as pretreatment processes. Also, 10~50 wt% of yeast for 3~6 days was used for fermentation process. The yield of cellulosic ethanol was decided in the fermentation process. The optimum pretreatment condition was 375W of ultrasonic power and 30 min of hydration time using 20 wt% of $H_2SO_4$ and 2 h of the acidic saccharification time. Finally, the optimum fermentation condition was at the condition of 30 wt% of yeast and 3 days of fermentation time.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.120-128
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• 2005

In the construction industry, due to the cost rise of raw material for concrete, we have looked into recycling by-products which came from foundry. When using the Ground Granulated Blast-Furnace Slag(SG), it is good for enhancing the qualities of concrete such as reducing hydration heat, increasing fluidity, long-term strength and durability, but it has some problems : construction time is increased or the rotation rate of form is decreased due to low development of early strength. In this study, therefore, to enhance the early strength of SG mortar, we used some alkali activators(KOH, NaOH, $Na_2CO_3$, $Na_2SO_4$, water glass, $Ca(OH)_2$, alum. This paper deals with reacted products, setting time, heat evolution rate, flow and the strength development of SG cement mortar activated by alkali activators. From the results, if alkali activators were selected and added properly, SG is good for using as the materials of mortar and concrete.