• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.473-474
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• 2010

This high pressure synchrotron X-ray diffraction study examined the change of bulk modulus of C-S-H(I), core material creating strength in alkali-activated slag cement as well as structural model of C-S-H, mainly attributed to Al-substitution for Si, which occurs at the bridging tetrahedral sites in dreierketten silicate chains in the nanostructure of C-S-H(I). This study presents that Al-substitution in C-S-H(I) does not affect the bulk modulus of C-S-H(I), which is surprising because many researchers have expected that Al-substitution should induce some critical change in mechanical properties of C-S-H(I).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.230-238
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• 1996

Recently, square hollow section (S.H.S) is frequently used for column and H-section for beam of steel building structures. The connection between S.H.S column and H-beam is found to weaken the rotational restraint of the joint. Several types of detail to overcome the problem have been suggested for the connection between concrete filled S.H.S column and concrete composited H-bean In this paper, modelling technique to monitor the behavior of the connections is proposed. Then, Drucker-Prager yield criteria is introduced to simulate yield behavior of in-fill concrete while Von-Mises was used in earlier works. Gap-elements are also introduced to simulate the interaction between S.H.S columns and the in-fill concrete as in privious papers. axial forces are applied to S.H.S columns and made to vary in intensity and eccentricity.

• Communications of the Korean Mathematical Society
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• v.15 no.1
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• pp.123-131
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• 2000

Let {X(t) : t $\geq$B 0} be a Symmetric $\alpha$ Stable and H-Self-similar process with stationary increments. We examine a.s. Holder unboundedness of S$\alpha$S H-sssi Chentsov processes and H-sssi Chentsov fields for order ${\gamma}$>H. Finally, we prove a.s. Holder continuity of S$\alpha$S H-sssi processes with ergodic seating transformations for the case of H>1/$\alpha$.

• Journal of Plant Biology
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• v.19 no.4
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• pp.95-99
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• 1976

This work deals with different extraction media and reaction mixtures on photosystem II activity of Spinach chloroplasts. The photoreduction rate of ferricyanide and DPIP by intact chloroplasts which extracted with four kinds of extraction media; S-Tris-N pH 7.2, 8.0, S-Tricine-N pH 7.2, 8.0, was measured in five kinds of reaction mixtures; S-Tris-N pH 7.2, 8.0, S-Tricine-N pH 7.2, 8.0, 0.05 M-Tris pH 7.2. The extraction medium which shows the highest photoreduction rate was S-Tris-N at pH 7.2 and S-Tricine-N at pH 8.0. As to the reaciton mixture, S-Tricine-N pH 8.0 showed the highest rate. On the complex effects of extraction media and reaction mixtures, the highest photordeuction rate of Hill oxidant by intact chloroplasts was obtained by S-Tris-N pH 7.2 extraction medium and S-Tricine-N pH 8.0 reaction mixture. The second highest activity was obtained by S-Tricine-N pH 8.0 extraction medium and reaction mixture.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.65-75
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• 2017

C-S-H phase is the most abundant reaction product, occupying about 50~60% of cement paste volume. The phase is also responsible for most of engineering properties of cement paste. This is not because it is intrinsically strong or stable, but because it forms a continuous layer that binds together the original cement particles into a cohesive whole. The binding ability of C-S-H phase arises from its nanometer-level structure. In terms of chloride penetration in concrete, C-S-H phase is known to adsorb chloride ions, however, its mechanism is very complicated and still not clear. The purpose of this study is to examine the interaction between chloride ions and C-S-H phase with various Ca/Si ratios and identify the adsorption mechanism. C-S-H phase can absorb chloride ions with 3 steps. In the C-S-H phase with low Ca/Si ratios, momentary physical adsorption could not be expected. Physical adsorption is strongly dependent on electro-kinetic interaction between surface area of C-S-H phase and chloride ions. For C-S-H phase with high Ca/Si ratio, electrical kinetic interaction was strongly activated and the amount of surface complexation increased. However, chemical adsorption could not be activated for C-S-H phase with high Ca/Si ratio. The reason can be explained in such a speculation that chloride ions cannot be penetrated and adsorbed chemically. Thus, the maximum chloride adsorption capacity was obtained from the C-S-H phase with a 1.50 Ca/Si ratio.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.379-384
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• 1996

The H2S sensing mechanism of CuO-SnO2 was confirmed by analyzing the electrical-resistance variation with temperature under an H2S atmosphere. While the resistance of CuO-SnO2 thick film at N2+H2S atmosphere was almost invariant with change in temperature it increased with increasing temperature for air +H2S atmos-phere. This behavior was analyzed using an equation derived from a basic assumption based on the H2S sensing mechanism proposed before. the experimental results are sufficiently explained with the equation derived which showed that the H2S sensing mechanism was reasonable. The equation also gave a detailed analysis and physical meaning to the behavior of the resistance variation with change in H2S concentration.

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.107.1-107.1
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• 2000

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.2
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• pp.153-160
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• 2023

In this study, nano-sized C-S-H crystals were synthesized using the liquid phase reaction method and their properties were investigated. The synthesized C-S-H crystals were added to the cement composite in suspension form to determine their effect on the hydration properties of the cement. The amount of chemical admixture was varied to obtain nano-sized C-S-H crystals with optimal agglomerated morphology, and SEM photographs were analyzed. A cleaning process was added to remove harmful substances other than the synthesiz ed C-S-H crystals. It was found that the concentration of harmful substances was reduced in the case of C-S-H crystals subjected to the cleaning process. The synthesized C-S-H suspensions were prepared with and without the cleaning process, and cement composites were prepared with the cement weight content as the main variable. The effect of C-S-H crystals on the initial hydration properties of the cement was confirmed by microhydration heat analysis. In addition, mortar specimens were prepared to measure the compressive strength over time. The test results showed that the nano-sized C-S-H crystals act as nucleation sites in the cement paste to promote the early hydration of the cement and increase the early compressive strength.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.2
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• pp.138-145
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• 2011

In this paper time series wave data are simulated by the Monte Calo method using random numbers to generate random phases of the wave signal. The simulated wave signasl are used to study the characteristics of freak waves. Various sea states are represented by combinations of the significant wave height $H_s$ defined in the spectrum method and the significant wave steepness $S_s$. For a fixed value of $S_s$, the probability of the occurrence of the freak wave is decreased as $H_s$ increases. For a fixed value of $H_s$ the probability of the occurrence of the freak wave increases as $S_s$ increases. The average value of the maximum wave height increase as $S_s$ increases, but the average height of freak wave remains the same and the value approaches two times of $H_s$. For the fixed value of $S_s$, average kurtosis of wave elevation increases as $H_s$ increases, but for a fixed $H_s$, the average kurtosis decreases as $S_s$ increases. The average of abnormality index(AI) is around 2.11 irregardless of $H_s$ and $S_s$. The maximum value of AI lies between 2.5 - 3.0. Therefore it is conjectured that AI maximum due to linear focusing is 3.0.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.871-872
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• 2009

본 연구에서는 석탄가스에 함유된 $H_2O/H_2S$ 농도변화에 따른 세가지 종류의 아연계 탈황제의 반응성능을 회분식 유동층반응기에서 분석하였다. 가스화에서 생성되는 가스의 조성은 모사가스를 이용하여 입구의 $H_2O$와 $H_2S$ 농도를 변화시켜 실험을 수행하였다. $H_2O$의 농도는 5%부터 30%까지 $H_2S$의 농도는 0.5%에서 2%로 변화시켜 탈황성능을 분석하였다. 실험 결과 $H_2O$의 농도가 증가할수록 탈황성능이 감소하였다. 입구의 $H_2S$ 농도가 증가할수록 탈황반응기 후단의 $H_2S$ 농도 역시 증가하였으나, 탈황성능은 최저 99.5%로 건식탈황제를 이용하여 99% 이상의 $H_2S$ 제거 성능을 보이는 것을 확인하였다.