• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.133-142
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• 2008

This paper studies the early-aged chloride binding capacity of various blended concretes including OPC(ordinary Portland cement), PFA(pulversied fly ash), GGBFS(ground granulated blast furnace slag) and SF(silica fume) cement paste. Cement pastes with 0.4 of a free water/binder ratio were cast with chloride admixed in mixing water, which ranged from 0.1 to 3.0% by weight of cement and different replacement ratios for the PFA, GGBFS and SF were used. The content of chloride in each paste was measured using water extraction method after 7 days curing. It was found that the chloride binding capacity strongly depends on binder type, replacement ratio and total chloride content. An increase in total chloride results in a decrease in the chloride binding, because of the restriction of the binding capacity of cement matrix. For the pastes containing maximum level of PFA(30%) and GGBFS(60%) replacement in this study, the chloride binding capacity was lower than those of OPC paste, and an increase in SF resulted in decreased chloride binding, which are ascribed to a latent hydration of pozzolanic materials and a fall in the pH of the pore solution, respectively. The chloride binding capacity at 7 days shows that the order of the resistance to chloride-induced corrosion is 30%PFA > 10%SF > 60%GGBFS > OPC, when chlorides are internally intruded in concrete. In addition, it is found that the binding behaviour of all binders are well described by both the Langmuir and Freundlich isotherms.

• Journal of Korean Society of Forest Science
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• v.61 no.1
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• pp.8-14
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• 1983

This study was to diagnose the ontogenetic ability of drought tolerance in trees, and was to investigate the seasonal changes in tissue-water relations parameters, ${\pi}_o$, ${\pi}_p$, $E_{max}$, $N_s/DW$, $V_o/W_s$ and $RWC_{(tlp)}$, obtained from P-V curves on the Pinus koraiensis and Abies holophylla shoots. The results obtained are as follows; 1) Seasonal changes of original osmotic pressure at maximum turgot, ${\pi}_o$, were -1.2 to -1.6 MPa in Pinus koraiensis and -1.4 to -1.7 MPa in Abies holophylla. 2) Seasonal changes of osmotic pressure at incipient plasmolysis, ${\pi}_p$, were -1.8 to -2.1 MPa in Pinus koraiensis and -1.6 to -2.1 MPa in Abies holophylla. 3) Seasonal changes of relative water content at incipient plasmolysis, $RWC_{(tlp)}$, were 70 to 77% in Pinus koraiensis and 69 to 85% in Abies holophylla. 4) Seasonal changes of maximum bulk modulus of elasticity at maximum hydration, $E_{max}$, were 2.2 to 6.3 MPa in Pinus koraiensis and 3.1 to 7.9 MPa in Abies holophylla. 5) Seasonal changes of number of osmoles of solute in symplasm versus dry weight, $N_s/DW$, were 0.5 to 1.3 in Pinus koraiensis and 0.3 to 1.0 in Abies holophylla. 6) Seasonal changes of original osmotic water volume versus total water volume (symplasmic and apoplastic water), $V_o/W_s$, were 55 to 65%r in Pinus koraiensis and 40 to 65% in Abies holophylla. Consequently, as the comparative values of ${\pi}_o$, ${\pi}_p$, $E_{max}$, $N_s/DW$, $V_o/W_s$, and $RWC_{(tlp)}$, it might be suggested that Abies holophylla shoot could have more or less a greater ability of drought tolerance as compared with Pinus koraiensis shoot.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.67-73
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• 2011

In this study, it was investigated compressive strength generation of concrete using high volume mineral admixture obtaining fundamental data for the application of concrete structure in construction field. For this, it was evaluated compressive strength with unit binder contents($310{\sim}410kg/m^3$), replacement ratio of mineral admixture(70~90%), unit water contents($140{\sim}150kg/m^3$) and curing temperature in the normal strength range. Also, after producing mock-up structure, hydration heat and compressive strength generation was evaluated to examine properties in the concrete member. In case of concrete using a large amount of industrial byproducts which was reviewed in this study, it is possible to secure compressive strength more than 24MPa at age 28days with about $13^{\circ}C$ ambient temperature of curing condition and that is considered to be applied to structure at construction site.

• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.285-291
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• 2014

Partial replacement of cement with blast furnace slag has many advantages such as the reduction of construction fee, the decrease of hydration heat and the increase of long-term strength. Hence, slag is widely used in practice. This study investigates the effect of slag on the rheological properties of cement paste and mortar. Three different types of slag (BS1, BS2 and BS3) with five different contents (0, 20, 40, 60 and 80 wt.%) were used to replace the cement. Each type of slag has different fineness. Water to binder ratio was 0.5. Test results showed that the partial replacement of BS1 and BS2 decreased flow and increased O-lot flow time, whereas that of BS3 caused an opposite effect, i.e., increased flow and decreased O-lot flow time. It was found that there was a good corelation between the values of yield stress and flow.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.303-310
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• 2004

The purpose of this study was to investigate the effect of using method and replacement ratio of limestone powder and water-cement ratio on the compressive strength and the resistance to sulfate attack of mortar incorporating limestone powder as fundamental study to use limestone powder as an addition for concrete. As a results, The method using limestone powder as a part of cement showed decrease of the compressive strength of mortar. The strength of mortar incorporating limestone powder almost decided upon unit cement content. It was recognized that the method replacing limestone powder as a part of cement was effective to decrease the heat of hydration in concrete. The method using limestone powder as a part of fine aggregate showed the considerable increase of the strength and resistance to sulfate attack of concrete. Furthermore, it was recognized that the method using limestone powder as a part of fine aggregate were effective materials as an addition for concrete in view of the improvement of strength and resistance to sulfate attack.

• Biomolecules & Therapeutics
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• v.28 no.6
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• pp.542-548
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• 2020

Naturally derived diosmetin and its glycoside diosmin are known to be effective in treating inflammatory disease. This study was performed to determine whether diosmin and diosmetin have the effect of improving atopic dermatitis in a 2,4-dinitrochlorobenzen (DNCB)-induced atopic dermatitis (AD) model. DNCB was used to establish AD model in hairless mice. Skin moisture, serum immunoglobulin E (IgE), interleukin 4 (IL-4), and histological analysis were performed to measure the effectiveness of diosmin and diosmetine to improve AD. IL-4 levels were also measured in RBL-2H3 cells. Administration of diosmetin or diosmin orally inhibited the progress of DNCB-induced AD-like lesions in murine models by inhibiting transdermal water loss (TEWL) and increasing skin hydration. Diosmetin or diosmin treatment also reduced IgE and IL-4 levels in AD-induced hairless mouse serum samples. However, in the in vitro assay, only diosmetin, not diosmin, reduced the expression level of IL-4 mRNA in RBL-2H3 cells. Diosmin and diosmetine alleviated the altered epidermal thickness and immune cell infiltration in AD. Diosmin is considered effective in the cure of AD and skin inflammatory diseases by being converted into diosmetin in the body by pharmacokinetic metabolism. Thus, oral administration of diosmetin and diosmin might be a useful agent for the treatment of AD and cutaneous inflammatory diseases.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.17-25
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• 2010

We studied on the watertightness improvement of cementitious material for durability enhancement of concrete. For improvement of watertightness of OPC and OPC with fly ash, we used various materials with watertightness properties to OPC and OPC with fly ash. The performance of watertightness improvement of cementitious materials closely related to formation of CSH by pozzolanic reaction and to reducing of size of contact angle in cement pore by using organic fatty acid. And volume of CSH formation at early hydration have an influence of watertightness improvement and reduction of long-term water absorption rate. In using of fly ash, improvement of workability by using the spherical fly ash caused to densify on the structures of cement material and CSH formation by pozzolanic reaction and cement using fly ash also caused watertightness improvement of cementitious materials. For improvement of concrete durability by watertightness, cementitious materials need using watertightness materials and at using fly ash, also it have to the effect of improvement of watertightness of cementitious materials by pozzolanic reaction.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.55-60
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• 2018

In this study investigated the Controlled Low Strength Materials using coal ash and steel slag(KR slag) as the main material in the thermal power plant classified as waste resource. Bottom ash and KR slag are mixed at a ratio of 7: 3 to expand the use of industrial by-products through carbonate($CO_2$-fixation) reactions and inhibit the exudation of heavy metals. The results showed that the water content increased as the content of bottom ash increased. It was confirmed that as the powder content increased, the bleeding ratio decreased. Also, as the content of one kind of ordinary portland cement (OPC) decreased, activation of hydration reaction decreased and compressive strength decreased. However, when the mixed composition is appropriately adjusted, the compressive strength of 2.0 MPa required for the controlled low-strength material can be satisfied.

• Journal of the Korean Magnetic Resonance Society
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• v.14 no.2
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• pp.55-75
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• 2010

An ion-exchanged reaction of $MnCl_2$ with Al-incorporated solid core/mesoporous shell silica (AlSCMS) followed by calcinations generated manganese species, where average oxidation state of manganese ion is 3+, in the mesoporous materials. Dehydration results in the formation of $Mn^{2+}$ ion species, which can be characterized by electron spin resonance (ESR). The chemical environments of the manganese centers in Mn-AlSCMS were investigated by diffuse reflectance, UV-VIS and ESR spectroscopic methods. Upon drying at 323 K, part of manganese is oxidized to higher oxidation state ($Mn^{3+}$ and $Mn^{4+}$) and further increase in (average) oxidation state takes place upon calcinations at 823 K. It was found that the manganese species on the wall of the Mn-AlSCMS were transformed to tetrahedral $Mn^{3+}$ or $Mn^{4+}$ and further changed to square pyramid by additional coordination to water molecules upon hydration. The oxidized $Mn^{3+}$ or $Mn^{4+}$ species on the surfaces were reversibly reduced to $Mn^{2+}$ or $Mn^{3+}$ species or lower valances by thermal process. Mn(II) species I with a well resolved sextet was observed in calcined, hydrated Mn-AlSCMS, while Mn (II) species II with g = 5.1 and 3.2 observed in dehydrated Mn-AlSCMS. Both species I and II are considered to be non-framework Mn(II).

• Polymer(Korea)
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• v.33 no.5
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• pp.485-489
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• 2009

The temperature dependence of the structure of micelles formed by a deuterated polystyrene-poly(ethylene oxide) diblock copolymer (dPS-PEO) in heavy water were investigated with small-angle neutron scattering (SANS). SANS data were analyzed using the hard-sphere structure factor in combination with the form factor of a core-shell model. The micelle aggregation number and corona radius were obtained from the fits to the SANS data. The micelle aggregation numbers varied with temperature from 229 at $25^{\circ}C$ to 240 at $45^{\circ}C$, with a corresponding increase in the core radius. However, the shell thickness of micelles decreased with increasing temperature from 6.2 to 5.8 nm. These structural changes of micelles might be ascribed to the decrease in the hydration volume per hydrophilic group in the corona because of the increase in hydrophobicity of the PEO block with increasing temperature.