• Transactions on Electrical and Electronic Materials
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• 제4권3호
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• pp.19-24
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• 2003

The experimental and simulation study of insulator failure by cement growth on suspended insulators (16,500kgf) for transmission line was discussed. To get more practical and analytic calculation results, the advanced program was used. This analysis tool was possible to calculate stress behaviors with mechanical loading when cement displacement happened. From simulation results, the. cement displacement changed with linear according to temperature. The shear stress was about $7 kgf/mm^2$ at $0.07\%$ displacement provided from $200^{\circ}C$, then it could be seen that the cement would be fractured even if $0.07\%$ displacement acted, because the cement had about $7-9 kgf/mm^2$ flexure strength. The curve patterns of shear stress with the increase of mechanical loading were changed at $0.02\%$ as a turning point, when the cement displacement was over $0.02\%$ the shear stresses decreased reversely with the increase of mechanical loading. From analysis on porcelain body it was known that there were enough margin to protect the fracture of porcelain body before the cement

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.476-479
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• 2002

The ageing cause in many porcelain suspension insulators which occur on transmission and distribution line with dead-end stings is mechanical stress in interface between porcelain and cement materials. It is known that the principal mechanical stress which give electrical failure is the results of the displacement is due to cement growth. We studied the effect of cement displacement resulting environmental ageing parameters on porcelain insulator mechanical properties for transmission line by simulation (ANSYS/NASTRAN program) and test methods. These simulation analysis and experimental results show that cement volume growth affects severely to be mechanical failure ageing.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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• pp.61-65
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• 2008

This study, having combined and displaced blast furnace slag("BS" hereinafter) known as admixture material that delays hydration reaction with coarse particle cement("CC" hereinafter) collected in particle classification method during ordinary portland cement("OPC" hereinafter), reviewed the hydration heat characteristics affecting the concrete. To reduce hydration heat, the study plain-mixed which used 100% OPC for W/B 50% level 1, displaced CC at level 3 of 25%, 50% and 75% for OPC, and by displacing BS with admixture material at level 5 of 0%, 20%, 40%, 60% and 80% for cement(OPC+CC), experimented totally 16 batches. As a result of experiment, in the case of flow, the more CC displacement rate increased, the more it tended to decrease, and the more BS displacement rate increased, the more it decreased. Also, as for simple adiabatic temperature rise by the CC and BS displacement rates, it decreased as displacement rate increased, and particularly in the case of displaced BS of 80%, It showed temperature reduction effect of about 63% companing with plain. Compressive strength decreased in proportion to displacement rate, however strength reduction increment was shown to decrease with age progress.

• Journal of Korean Neurosurgical Society
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• 제43권4호
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• pp.212-214
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• 2008

We report a rare case of delayed cement displacement after balloon kyphoplasty in patient with K$\ddot{u}$mmell's desease. A 78-year-old woman with K$\ddot{u}$mmell's desease at T12 level received percutaneous balloon kyphoplasty. Two months after surgery, the patient complained of progressive severe back pain. Computed tomographic scans revealed a breakdown of the anterior cortex and anterior displacement of bone cement. Although this complication is very rare, it is likely to occur in treatment of K$\ddot{u}$mmell's disease accompanying anterior cortical defect.

• 한국지반신소재학회논문집
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• 제12권4호
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• pp.99-107
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• 2013

매입말뚝의 수평저항 특성을 고찰하기 위하여 매입말뚝에 대한 수평재하시험을 실시하여 수평하중과 수평변위관계를 분석하였다. 말뚝수평재하시험은 시멘트 밀크가 말뚝매입길이의 50%, 70%, 100%로 주입된 6개의 말뚝에 대하여 실시하였다. 시멘트 밀크의 주입비(시멘트 밀크 주입길이/말뚝의 길이)는 매입말뚝의 수평변위, 항복하중, 수평지지력에 큰 영향을 미치는 것으로 나타났다. 시멘트 밀크의 주입비가 증가할수록 매입말뚝의 수평변위가 발생되기 시작하는 위치는 지표면에 가까워지며 말뚝의 수평변위는 감소한다. 그리고 말뚝의 수평지지력과 항복하중은 시멘트 밀크 주입비가 증가할 수록 크게 나타났다. 시멘트 밀크 주입비가 1인 매입말뚝의 항복하중과 극한수평지지력은 시멘트 밀크 주입비가 0.5인 경우보다 약 2~3배 정도 크게 나타났다.

• Smart Structures and Systems
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• 제24권2호
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• pp.157-171
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• 2019

This study investigated the effects of the geometric parameters of superelastic shape memory alloy (SE SMA) fibers on the pullout displacement recovering and self-healing capacity of reinforced cementitious composites. Three diameters of 0.5, 0.7 and 1.0 mm and two different crimped lengths of 5.0 and 10.0 mm were considered. To provide best anchoring action and high bond between fiber and cement mortar, the fibers were crimped at the end to create spear-head shape. The single fiber cement-based specimens were manufactured with the cement mortar of a compressive strength of 84 MPa with the square shape at the top and a dog-bone shape at the bottom. The embedded length of each fiber was 15 mm. The pullout test was performed with displacement control to obtain monotonic or hysteretic behaviors. The results showed that pullout displacements were recovered after fibers slipped and stuck in the specimen. The specimens with fiber of larger diameter showed better displacement recovering capacity. The flag-shaped behavior was observed for all specimens, and those with fiber of 1.0 mm diameter showed the clearest one. It was observed that the length of fiber anchorage did not have a significant effect on the displacement recovery, pullout resistance and self-healing capacity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
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• pp.104-107
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• 2003

The ageing cause in many porcelain suspension insulators which occur on transmission and distribution line with dead-end stings is mechanical stress in interface between porcelain and cement materials. It is known that the principal mechanical stress which give electrical failure is the results of the displacement is due to cement growth. We studied an analysing method to find out a deformation of brittle porcelain with a thermal expansion of cement for suspension insulator. These simulation analysis and experimental results show that cement volume growths affect severely to be mechanical failure ageing. These simulation analysis and experimental results show that axial loading affects of Porcelain insulators severely to be mechanical failure ageing.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.159-162
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• 2006

This study generally compared and investigated cement type and quality of China and Korea. Cement in Korea is divided into five such as ordinary, high early strength, moderate heat, low heat and sulfate resistance portland cement. However cement in China is divided into portland cement($P{\cdot}I,\;P{\cdot}II$) and ordinary portland cement($P{\cdot}O$) with admixture displacement ratio and it is again divided into 6 level and 7 level with 28 days compressive strength. In addition China classified cement into several standards, such as Mgo, SO3,, igloss, blame, setting time, stability, strength, alkali and sampling test. Therefore it should be careful to conclude so quickly without right understanding whether quality of China cement is bad or good. The better way to evaluate China cement is synthetically understanding a value engineering and consumer awareness.

• Computers and Concrete
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• 제11권1호
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• pp.63-73
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• 2013

In this study, the effect of reducing cement by proportional addition of waste powder rubber on the performance of concrete under impact three-point bending loading were investigated experimentally and numerically. Concrete specimens were prepared by adding 5%, 10% and 20 % of rubber powder as filler to the mix and decreasing the same percentage of cement. For each case, three beams of $50mm{\times}100mm{\times}500mm$ were loaded to failure in a drop-weight impact machine by subjecting them to 20 N weight from 300mm height, while another three similar beams were tested under static load. The bending load-displacement behavior was analyzed for the plain and rubberized specimens, under static and impact loads. A three dimensional finite-element method simulation was also performed by using LUSAS V.14 in order to study the impact load-displacement behavior, and the predictions were validated with the experimental results. It was observed that, despite decreasing the cement content, the proportional addition of powder rubber until 10% could yield enhancements in impact tup, inertial load and bending load.

• Steel and Composite Structures
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• 제21권3호
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• pp.461-477
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• 2016

Steel-concrete-steel (SCS) sandwich composite wall has been proposed for building and offshore constructions. An ultra-lightweight cement composite with density1380 kg/m3 and compressive strength up to 60 MPa is used as core material and inter-locking J-hook connectors are welded on the steel face plates to achieve the composite action. This paper presents the numerical models using nonlinear finite element analysis to investigate the load displacement behavior of SCS sandwich walls subjected to axial compression. The results obtained from finite element analysis are verified against the test results to establish its accuracy in predicting load-displacement curves, maximum resistance and failure modes of the sandwich walls. The studies show that the inter-locking J-hook connectors are subjected to tension force due to the lateral expansion of cement composite core under compression. This signifies the important role of the interlocking effect of J-hook connectors in preventing tensile separation of the steel face plates so that the local buckling of steel face plates is prevented.