• Structural Engineering and Mechanics
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• 제13권2호
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• pp.171-186
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• 2002

Static and dynamic penetration tests of reinforced concrete (RC) slab specimens are described and discussed. The experimental study was aimed at a better understanding of mechanisms that are involved in dynamic penetration, through their identification in static tests, and by establishing their relative influence in similar dynamic cases. The RC specimens were $80{\times}80-cm$ square plates, and they were made of 30 MPa concrete. The non-deforming steel penetrator was a 50-mm diameter steel rod with a conical nose of 1.5 aspect ratio. Impact penetration tests were carried out with an air gun, which launched the projectiles at velocities of up to 300 m/sec. The static tests were conducted using a closed loop displacement control actuator, where the penetrator was pushed at a constant rate of displacement into the specimen. The static tests reveal important mechanisms that govern the penetration process and therefore contribute to a better understanding of RC barriers resistance to non-deforming projectiles impact.

• 한국염색가공학회지
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• 제19권1호
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• pp.24-30
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• 2007

Heat storage/release system in textile is a useful tool to increase energy efficiency and enhance comfortable microclimate of clothing. Phase change materials(PCM) are used in regulating storage and release properties of thermal energy. To investigate the temperature regulating ability of fabrics with PCM microcapsule(PCMMc), Nylon fabrics were coated with PCMMc via wet processing and they were characterized by SEM, DSC and infrared thermal analyzer. Also, water moisture transpiration, water penetration resistance, peel strength and washing durability of the fabrics were assessed. The water vapor permeation and water penetration resistance decreased with increasing PCMMc content. In DSC analysis, it can be seen that the microencapsulated fabric showed both exothermic md endothermic phenomena at specific temperature. Peel strength was decreased with increasing PCMMc content.

• Corrosion Science and Technology
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• 제13권6호
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• pp.209-213
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• 2014

Due to the increasing of interest about the eco-friendly concrete, it is increased to use concretes containing by-products of industry such as fly ash(FA), ground granulated blast furnace slag(GGBFS), silica fume(SF), and etc. Especially, these are well known for improving the resistances to reinforcement corrosion in concrete and decreasing chloride ion penetration. The purpose of this experimental research is to evaluate the resistance against corrosion of reinforcement of high volume fly ash(HVFA) concrete which is replaced with high volume fly ash for cement volume. For this purpose, the concrete test specimens were made for various strength level and replacement ratio of FA, and then the compressive strength and diffusion coefficient for chloride ion of them were measured for 28, 91, and 182 days, respectively. Also, corrosion monitoring by half cell potential method was carried out for the made lollypop concrete test specimens to detect the time of corrosion initiation for reinforcement in concrete. As a result, it was observed from the test results that the compressive strength of HVFA concrete was decreased with increasing replacement ratio of FA but long-term resistances against reinforcement corrosion and chloride ion penetration of that were increased.

• International Journal of Concrete Structures and Materials
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• 제8권4호
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• pp.301-307
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• 2014

Rice husk ash (RHA) is classified as a highly reactive pozzolan. It has a very high silica content similar to that of silica fume (SF). Using less-expensive and locally available RHA as a mineral admixture in concrete brings ample benefits to the costs, the technical properties of concrete as well as to the environment. An experimental study of the effect of RHA blending on workability, strength and durability of high performance fine-grained concrete (HPFGC) is presented. The results show that the addition of RHA to HPFGC improved significantly compressive strength, splitting tensile strength and chloride penetration resistance. Interestingly, the ratio of compressive strength to splitting tensile strength of HPFGC was lower than that of ordinary concrete, especially for the concrete made with 20 % RHA. Compressive strength and splitting tensile strength of HPFGC containing RHA was similar and slightly higher, respectively, than for HPFGC containing SF. Chloride penetration resistance of HPFGC containing 10-15 % RHA was comparable with that of HPFGC containing 10 % SF.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.13-17
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• 2007

The green roof industry have been developed with Europe, North America, Japan. At the same time, being recognized the important of green roofs in domestic industry and we just start to develop the relative technology as analyzing the future direction of advanced technology. Recently, local self-government including Seoul support the system for green roof which provide 50% of working expenses form of Matching Fund by Seed Money. As years go by, the number of build up the green roof has gradually increased to be proved. At this result caused by management of system in government, unstructured construction system, low development of support technology. In this study as analyzing the present of technical development, supporting by law and system for the advanced waterproofing and root penetration resistance technology, we suggest the development direction of it to be compared with application advanced technology and we could strengthen the international competitiveness to be industrialized the green roof considering system, technology, human infrastructure.

• Carbon letters
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• 제16권2호
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• pp.107-115
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• 2015

Impact damages induced by a low-velocity impact load on carbon fiber reinforced polymer (CFRP) composite plates fabricated with various stacking sequences were studied experimentally. The impact responses of the CFRP composite plates were significantly affected by the laminate stacking sequences. Three types of specimens, specifically quasi-isotropic, unidirectional, and cross-ply, were tested by a constant impact carrying the same impact energy level. An impact load of 3.44 kg, corresponding to 23.62 J, was applied to the center of each plate supported at the boundaries. The unidirectional composite plate showed the worst impact resistance and broke completely into two parts; this was followed by the quasi-isotropic lay-up plate that was perforated by the impact. The cross-ply composite plate exhibited the best resistance to the low-velocity impact load; in this case, the impactor bounced back. Impact parameters such as the peak impact force and absorbed energy were evaluated and compared for the impact resistant characterization of the composites made by different stacking sequences.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.148-149
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• 2016

In this paper, the increase in chloride resistance of footing concrete at coastal area was evaluated by replacement of Mineral Admixture. In KBC 2009, the footing concrete's minimum specific concrete strength at coastal area is determined to 35MPa. However, this is criteria only based on the strength aspect. Thus, it is not considered to increase the chloride resistance by replacement of Mineral Admixture. According to the test results of chloride ions penetration resistance, 35MPa class concrete with OPC 100% shown inaccessible state. Low-strength (24~30MPa class) concretes with Mineral Admixture, however, presented better performances. In addition, chloride diffusion coefficient tests showed identical appearance. Therefore, the current KBC's chloride resistance criteria based on only concrete strength has to review for the reason it can cause many problems (ex. cost increases by growing concrete strength and the environmental issues by a lot of cement use).

• 한국지반공학회논문집
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• 제26권1호
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• pp.55-62
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• 2010

진동타입기에 의해 시공되는 강널말뚝의 관입속도를 예측하고자 수정 Ramberg-Osgood 모델을 적용하여 진동타입기의 주기운동에 따른 지반의 동적 저항력을 모사하고자 하였다. 수정 Ramberg-Osgood 모델을 규정짓는 다양한 인자는 현장시험을 통해 구한 동적 지반저항력곡선의 양상을 반영하여 결정하였는데 이때 매개변수로는 표준관입시험값(N값)을 이용하였다. 관입속도는 해석결과가 현장시험결과에 비해 작게 계산되었으며 관입깊이에 따른 관입 소요시간은 해석결과가 현장시험결과에 비해 크게 계산되어 해석결과가 현장시험결과에 비해 보수적인 값을 보여주었다.

• 한국지반환경공학회 논문집
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• 제16권2호
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• pp.45-52
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• 2015

철도궤도 하부구조물의 유지, 보수 및 과다설계에 따른 비용을 최소화하기 위하여 궤도 하부구조물의 강도 및 강성특성에 대한 정확한 평가는 필수적이다. 본 연구에서는 궤도 하부구조물의 상태를 평가하기 위한 콘 관입기(CPI)를 개발하였으며, 적용성 검증을 위하여 실내실험과 현장실험을 수행하였다. CPI를 이용한 철도궤도 하부구조물 평가의 결과로서 획득되는 결과는 동적 콘관입지수(DCPI), 원추관입저항력($q_c$), 마찰저항력($f_s$) 및 마찰력비(Fr)이다. 실험결과, 실내실험의 경우 도상자갈층에서 획득한 동적 콘 관입지수와 상부노반층에서 획득한 원추관입저항력, 마찰저항력 및 마찰비는 조성한 시료에 대하여 신뢰할 만한 결과를 보였다. 현장실험의 경우 도상자갈층의 경계면을 명확히 구분해 내었으며, 상부노반층의 불연속면을 감지하였다. 본 연구에서 개발된 CPI는 동적 관입과 정적 관입 방법을 이용함으로써 궤도 하부구조물 평가에 유용한 방법이 될 것이라 기대된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.417-418
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• 2009

해안 및 매립지 구조물은 염화물의 침투로 인해 매입된 철근의 피막파괴로 철근부식이 일어나 콘크리트 구조체에 열화가 급속하게 진행되기 때문에 앞으로의 해안 구조물의 수밀성, 내염해성을 필요로 한다. 따라서 본 연구에서는 내염해성 개선에 효과적인 액상형태의 Si/Al 복합 무기염을 모르타르에 적용하여 시간경과(7, 14, 28, 56일)에 따른 내염해특성을 파악하고자 하였다.