• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.599-604
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• 2011

In this study, we investigated the efficacy of ${\beta}$-cyclodextrin (${\beta}CD$) hydrorogel containing silk fibroin (SF) on healing burnt wound. Tosyl ${\beta}CD$ was conjugated to polyethyleneimine (PEI) using epichlorohydrin (EPI) as a cross-linker. The ${\beta}CD/PEI/SF$ hydrogel was applied on the back of mouse and then the efficacy of hydrogel was compared with both positive control group and negative control group. There was no wound healing efficacy showed neither in the drug loaded ${\beta}CD/PEI/SF$ hydrogel group nor in the drug unloaded ${\beta}CD/PEI/SF$ hydrogel group. On the other hand, in the positive control group, a significant reduction of the wound size after the usage of OTC hydrorogel was obtained. The burn-healing histological result showed a similar phenomenon. After hematoxylin-eosin staining the skin induced by burning, and the epithelial growth observed in the dermis, the efficacy of ${\beta}CD/PEI/SF$ hydrogel in healing burnt wound could not be clearly identified.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.127-136
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• 2015

To evaluate the effects of limestone powder and silica fume on the properties of high-strength high-volume ground granulated blast-furnace slag (GGBFS) blended cement concrete, this study investigated the rheology, strength development, hydration and pozzolanic reaction characteristics, porosity and pore size distribution of high-strength mortars with the water-to-binder ratio of 20, 50 to 80% GGBFS, up to 20% limestone powder, and up to 10% silica fume. According to test results, compared with the Portland cement mixture, the high-volume GGBFS mixture had much higher flow due to the low surface friction of GGBFS particles and higher strength in the early age due to the accelerated cement hydration by increase of free water; however, because of too low water-to-binder ratio and cement content, and lack of calcium hydroxide content, the pozzolanic reactio cannot be activated and the long-term strength development was limited. Limestone powder did not affect the flowability, and also accelerate the early cement hydration. However, because its effect on the acceleration of cement hydration is not greater than that of GGBFS, and it does not have hydraulic reactivity unlikely to GGBFS, compressive strength was reduced proportional to the replacement ratio of limestone powder. Also, silica fume and very fine GGBFS lowered flow and strength by absorbing more free water required for cement hydration. Capillary porosities of GGBFS blended mortars were smaller than that of OPC mortar, but the effect of limestone powder on porosity was not noticeable, and silica fume increased porosity due to low degree of hydration. Nevertheless, it is confirmed that the addition of GGBFS and silica fume increases fine pores.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.4
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• pp.242-248
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• 2001

A high resolution Chirp seismic profile and a multichannel seismic reflection profile were analysed to study the possibility of gas hydrate presence in the southwestern upper slope of the Ulleung Basin. The Chirp profile shows acoustic turbidity, acoustic void, and pockmarks, suggesting the presence of shallow gas in the sediments .Slope failures appear to have occurred in association with decomposition of gas hydrated sediments. A bottom-simulating reflector (BSR) is seen in subbottom depths of 60 to 110 m below the seafloor at water depths of 750 to 1130 m. The sediments above BSR are characterized by acoustic blanking probably due to amplitude reduction caused by a mixture of gas hydrate with sediments. The interval velocity above the BSR is 1,650 m/sec and it drops abruptly to 1,080 m/sec below the BSR. The sediment column between seafloor and the BSR thins with increasing water depth, which is very closely related to increasing geothermal gradient with increasing water depth in the Ulleung Basin.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.205-211
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• 2009

The Weightless Neural Network(WNN) has the advantage of the processing speed, less computability than weighted neural network which readjusts the weight. Especially, The behavior information such as sequential gesture has many serial correlation. So, It is required the high computability and processing time to recognize. To solve these problem, Many algorithms used that added preprocessing and hardware interface device to reduce the computability and speed. In this paper, we proposed the Ram based Sequential Cumulative Neural Network(SCNN) model which is sign language recognition system without preprocessing and hardware interface. We experimented with using compound words in continuous korean sign language which was input binary image with edge detection from camera. The recognition system of sign language without preprocessing got 93% recognition rate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.126-135
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• 2013

Recently, mass concrete with high flowability are widely used to improve the quality and constructability in the longer span construction of prestressed concrete bridges, but it may induce nonstructural cracks due to the hydration heat and autogenous shrinkage etc. The stresses in concrete were evaluated by various experiments and numerical analysis. The tensile stress in mass concrete was increased in connection with the accumulation of hydration heat. Moreover, large amount of autogenous shrinkage from powder type admixture could add the tensile stress to mass concrete near anchorage zone. The tensile stresses in anchorage zone by heat and autogenous shrinkage exceeded the tensile strength of early stage of concrete, and small amounts of stress increasement were shown in other parts of PSC girder.

• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.218-226
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• 2013

Of construction materials, cement and steel are the representative material that carbon dioxide. to reduce carbon emissions in the use of these materials The purpose of this study is low heat type blended cement, which is manufactured using a amount of cement than ordinary low heat blended cement. Low heat blended cement, mixing ratio of 10%, was investigated hydration properties and adiabatic temperature of concrete. The study in order to activate the reaction mineral admixture, a separate source of CaO and $SO_3$ areneeded. gypsum and lime, it expected amount of cement, low-carbon low-heat blended cement could reduce the hydration heat concrete than currentlyused low heat blended cement.

• Journal of the Korea Institute of Building Construction
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• v.15 no.6
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• pp.589-595
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• 2015

This study evaluated the in-site compressive strength development of high-strength concrete developed for the mass structures under cold weather condition. Two mock-up wall specimens with $2.0{\times}1.2{\times}1.0m$ in dimension were cured under an average temperature of $5^{\circ}C$. Core strengths measured at different locations of the mock-up walls were compared with the companion standard cylinder strengths. Test results revealed that the core strength of mock-up walls at an age of 3 days is higher by approximately 30% than the companion cylinder strength because of the high curing temperature effect generated from the heat of hydration of cementitious materials. Furthermore, comparisons with the prediction models based on maturity function confirmed that the effect of hydration heat on the curing temperature increase needs to be reflected to reasonably evaluate the on-site compressive strength development of concrete for mass elements.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.217-224
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• 2014

This study carried out to evaluate the hydration heat analysis and fundamental characteristics such as air content, slump and compressive strength for field application of low heat concrete with premixed cement. The results of experiment show that low heat concrete with premixed cement have sufficient performances on the workability and compressive strength. In addition, hydration heat analysis shows that low heat concrete with premixed cement make sure of target thermal cracking index. Therefore, it is desirable to apply the low heat concrete with premixed cement on pier foundation-column.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.39.1-39.1
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• 2011

가압경수로의 압력경계기기는 약 $300^{\circ}C$, 150기압의 고온고압수환경에서 가동되고 있다. 특히 가압기 밀림관은 고온수와, 저온수가 교차하는 부분으로 열성층 형성으로 열적, 기계적 피로 및 수화학환경이 더해진 부식피로 등에 의하여 손상을 받는다. PWR 원전에서 수화학환경은 대표적으로 용존산소(DO) 5ppb, pH 6~8, 용존수소(DH) <30 cc/kg, 온도 $316^{\circ}C$의 환경을 유지하게 된다. 가압기 밀림관에는 오스테나이트계 스테인리스강이 사용되는데, 오스테나이트계 스테인리스강은 고온 수화학환경에 민감한 것으로 알려져 있다. 따라서 오스테나이트계 스테인리강을 공기중에서의 기계적특성 및 피로특성을 향상시키기 위하여 질소를 첨가한 스테인리스강을 제조하여 PWR 원전환경에서의 피로균열성장특성을 평가하였다. 실험에 사용된 재료는 PWR 원전 가압기 밀림관 소재인 Type 347 스테인리스강에 0.0005 wt%가 첨가된 상용재와 0.11 wt% 질소가 첨가된 재료이다. 사용된 시편형상은 두께 5 mm, 폭 25.4 mm의 CT 시편이다. 수화학환경은 150기압, 온도 $316^{\circ}C$, 용존산소(DO) 5ppb, 용존수소(DH) 30 cc/Kg, pH는 약 7로 유지 하였으며, 응력비 0.1, 하중 반복속도 10Hz의 기계적 조건에서 하중제어로 시험을 진행하였다. 균열길이는 직류전위차법(Direct Current Potential Drop: DCPD)을 이용하여 측정하였다. 질소함량이 증가할수록 동일 사이클에서 균열길이가 늦게 성장하였고, 피로균열성장속도도 약간 늦어지는 것으로 나타났다. 각 스테인리스강의 피로파면 관찰결과 상용재는 약 1 ${\mu}m$의 산화물들이 생성되는 반면 질소첨가 스테인리스강은 약 0.1 ${\mu}m$정도 산화물이 생성되었다. 산화막의 두께도 질소가 첨가됨으로써 상용재에 비해 얇게 생성되었다. 따라서 질소가 첨가됨으로써 부식환경에서 내산화성이 향상되었으며, 이는 피로균열성장특성에 영향을 미치는 것으로 판단된다.

• 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.