• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.69-70
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• 2015

This study has attempted to derived an optimum fiber replacing ratio for practical use by measuring tensile strength and length deformation followed by variation of fiber replacing ratio among the basic characteristics of HPFRCC in order to evaluate the possibility of practical use of HPFRCC. As a result of performing experiment and research, the optimum replacement ratio was determined at the fiber replacing ratio of 1.5% when compressive strength, tensile strength and tensile stress-strain curve.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.75-76
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• 2015

This study has examined the impact resistance and blast resistance characteristics of HPFRCC as a research on impact resistance and blast resistance characteristics using high volume mortar and high velocity projectile for evaluating the protection performance of actual buildings as small quantity experiment of laboratory conditions is performed although there was an instance of performing research on mortar that has reinforced fiber followed by the rise of problems on the damage of human life and buildings created due to explosion and shock. As a result, the destruction loss area and depth have decreased in case of the surface compared to the rear side. As tensile strength and tenacity have increased with the increased fiber replacing ratio, a tendency of destruction loss area and depth getting decreased was shown as the impact resistance has increased.

• Steel and Composite Structures
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• 제34권6호
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• pp.909-927
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• 2020

This paper addresses the results of an experimental study involving 10 partially encased composite columns under concentric and eccentric compressive loads. Parameters such as slenderness ratio, ordinary reinforced concrete and fiber reinforced concrete, load eccentricity and bending axis were investigated. The specimens were tested to investigate the effects of replacing the ordinary reinforced concrete by fiber reinforced concrete on the load capacity and behavior of short and slender composite columns. Various characteristics such as load capacity, axial strains behavior, stiffness, strains on steel and concrete and failure mode are discussed. The main conclusions that may be drawn from all the test results is that the behavior and ultimate load are rather sensitive to the slenderness of the columns and to the eccentricity of loading, specially the bending axis. Experimental results also indicate that replacing the ordinary reinforced concrete by steel fiber reinforced concrete has no considerable effects on the load capacity and behavior of the short and slender columns and the proposed replacement presented very good results.

• 대한조선학회논문집
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• 제54권5호
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• pp.415-420
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• 2017

Insulation systems in Liquefied Natural Gas Carriers (LNGC) are vulnerable to sloshing impact and fatigue loads because of waves. If gas leaks into the primary barrier, the Flexible Secondary Barrier (FSB) prevents the leakage of gas in this system. Fatigue strength of the FSB largely depends on the behavior of composite materials. In this study, a new system is applied to the FSB using aramid fiber to improve the fatigue strength of the secondary barrier, with the intention of replacing conventional E-glass fibers. The manufacturing method involved varying the ratio of the aramid fiber to the E-glass fiber for optimum design of the FSB. The fatigue tests results of the secondary barrier using aramid fiber were superior to that using E-glass fiber. The statistical analysis is performed to obtain the fatigue test results and estimate the probability of failure as well as the design guideline of LNGC secondary barriers.

• Computers and Concrete
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• 제21권6호
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• pp.669-679
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• 2018

In this paper the behavior of reinforced concrete (RC) beam-column connections under cyclic loading was analyzed. The specimens, manufactured in a reduced-scale were made of (a) recycled aggregate concrete (RAC) by replacing 30% of natural coarse aggregate (NCA) with recycled coarse aggregate (RCA) and (b) RAC incorporating Polyethylene terephthalate (PET) fiber i.e., PET fiber-reinforced concrete (PFRC) at the joint region. PET fiber (aspect ratio=25) of 0.5% by weight of concrete used in the PFRC mix was obtained by hand cutting of post-consumer PET bottles. A reference specimen was also prepared using 100% of NCA and subjected to similar loading sequence. Comparing the results the structural behavior under cyclic loading of RAC specimens are quite similar to the reference specimens. Damage tolerance, load resisting capacity, stiffness degradation, ductility, and energy dissipation of the RAC specimens enhanced due to addition of PET fibers at the joint region. PFRC specimens also presented a lower damage indices and higher principal tensile stresses as compared to the RAC specimens. The results obtained gave experimental evidence on the feasibility of RAC for structural use. Using PET fibers as a discrete reinforcement is recommended for improving the seismic performance of RAC specimens.

• Steel and Composite Structures
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• 제23권5호
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• pp.543-555
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• 2017

The mechanical properties of steel fiber reinforced high strength concrete (SFRHSC) made with binary and ternary blends of metakaolin (MK) and ground pumice (GP) are investigated in this study. The investigated properties are ultrasonic pulse velocity ($U_{pv}$), compressive strength ($f_c$), flexural strength ($f_f$) and splitting tensile strength ($f_{st}$) of SFRHSC. A total of 16 steel fiber reinforced concrete mixtures were produced by a total binder content of $500kg/m^3$ for determining the effects of MK and GP on the mechanical properties. The design $f_c$ was acquired from 70 to 100 MPa by using a low water-binder ratio of 0.2. The test results exhibit that high strength concrete can be obtained by replacing the cement with MK and GP. Besides, correlations between these results are executed for comprehending the relationship between mechanical properties of SFRHSC and the strong correlations are observed between these properties. Moreover, two models in the gene expression programming (GEP) for predicting the $f_c$ of SFRHSC made with binary and ternary blends of MK and GP have been developed. The results obtained from these models are compared with the experimental results. These comparisons proved that the results of equations obtained from these models seem to agree with the experimental results.

• 한국산학기술학회논문지
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• 제16권1호
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• pp.8-14
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• 2015

지금까지 자동차 소재의 경량화 및 연소가스의 저감은 부품의 플라스틱화를 통하여 많은 진전이 있었다. 장섬유 보강 폴리프로필렌 소재가 적용된 프론트 엔드 모듈 캐리어는 플라스틱 구조부품 중에서 가장 성공적인 사례이다. 하지만, 장기 신뢰성 측면에서 볼 때, 자동차용 플라스틱 소재에 대한 피로거동 및 진동내구에 대한 더 많은 연구가 필요한 실정이다. 본 연구에서는 프론트 엔드 모듈 캐리어의 피로설계 및 해석의 기초가 되는 폴리프로필렌 장섬유 소재에 대한 내구성을 분석하였다. 피로수명과 응력진폭 또는 평균응력 간의 상관관계를 평가하기 위하여 다양한 응력비에서 피로실험을 수행하였다. 일정 응력진폭에서 응력비를 변화시킨 결과는 최대하중을 고정시킨 결과보다 피로수명의 변화가 응력비 증가에 따라 2~6% 크게 나타났다. 또한 주사전자 현미경을 통하여 장섬유 보강 폴리프로필렌 소재에 대한 피로균열의 발생, 전파의 파괴기구를 확인하였다.

• 대한조선학회논문집
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• 제59권4호
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• pp.207-213
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• 2022

LNG CCS which is a special type of cargo hold operated at -163℃ for transporting liquefied LNG is composed of a primary barrier, plywood, insulation panel, secondary barrier, and mastic. Currently, glass fiber is used to reinforce polyurethane foam. In this paper, we evaluated the possibility of replacing glass fiber-reinforced polyurethane foam with basalt fiber-reinforced polyurethane foam. We conducted a thermal conductivity test to confirm thermal performance at room temperature. To evaluate the mechanical properties between basalt and glass-fiber-reinforced polyurethane foam which is fiber content of 5 wt% and 10 wt%, tensile and an impact test was performed repeatedly. All of the tests were performed at room temperature and cryogenic temperature(-163℃) in consideration of the temperature gradient in the LNG CCS. As a result of the thermal conductivity test, the insulating performance of glass fiber reinforced polyurethane foam and basalt fiber reinforced polyurethane foam presented similar results. The tensile test results represent that the strength of basalt fiber-reinforced polyurethane foam is superior to glass fiber at room temperature, and there is a clear difference. However, the strength is similar to each other at cryogenic temperatures. In the impact test, the strength of PUR-B5 is the highest, but in common, the strength decreases as the weight ratio of the two fibers increases. In conclusion, basalt fiber-reinforced polyurethane foam has sufficient potential to replace glass fiber-reinforced polyurethane foam.

• 한국결정성장학회지
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• 제30권1호
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• pp.33-39
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• 2020

본 연구에서는ALC 패널을 대체하고자 석탄가스화 복합발전에서 배출되는 용융 슬래그를 주원료로 실리콘 웨이퍼 부산물로 발생하는 Si sludge를 발포제로 경량 지오폴리머를 제조하여 알칼리 활성화제의 몰 농도, W/S 비, Fiber, Polystyrene(스티로폼) 첨가에 따른 비중과 압축강도 등의 물리적 특성을 측정하고 ALC 판넬 대체 가능성을 분석/비교 하였다. W/S 비, 알칼리 활성화제의 몰 농도 조절을 통해 ALC 기준에 부합되는 시편을 만들 수는 없었으나 이를 섬유상 물질 및 스티로폼 등의 외부물질을 첨가하여 물성향상 한계의 벽을 뛰어넘고자 하였다. 유리섬유와 탄소섬유 첨가 지오폴리머는 ALC 패널의 기준에 도달하지 못했지만, 유리 섬유 0.3 wt.%를 첨가한 경우 압축강도가 3배 이상 증가했다는 면에서 경량 지오폴리머의 압축강도를 크게 향상시키는 방법으로 제시될 수 있었다. 스티로폼 첨가 시편의 경우 스티로폼 최대 첨가량은 5 0 vol.%였으며, 삽입물의 첨가 방법에 따라 물성이 크게 변화하였다. 단일 삽입물을 첨가한 경우 강도 17.8 MPa 밀도 0.996 g/㎤으로 ALC 패널 기준과 유사한 물성을 얻을 수 있었다. 향후연구를 통해 시편제조 재현성 및 제조방법의 어려움을 극복한다면, 스티로폼 삽입 지오폴리머는 ALC 패널을 대체할 가능성이 충분히 있다고 판단되었다.

• 콘크리트학회논문집
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• 제25권5호
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• pp.477-484
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• 2013

이 연구에서는 순환골재와 고로슬래그 미분말의 치환율에 따른 강섬유 보강 RC보의 구조성능 향상을 위하여 표준실험체(BSS), 성능개선 실험체로는 순환골재와 고로슬래그 미분말을 치환한 실험체(BRS시리즈), 순환골재와 고로슬래그의 치환율에 강섬유를 보강한 실험체(BSRS시리즈)로 총 11개의 실험체를 1/2축소 제작하여 실험을 수행하였다. 실험을 통하여 얻어진 결과를 비교 분석하여 하중-변위, 파괴형태, 최대내력 등을 규명함으로써 구조성능의 개선정도를 평가하였다. 실험 결과 순환골와 고로슬래그 미분말을 치환한 콘크리트에 강섬유를 보강한 실험체(BSRS시리즈)의 경우 표준실험체(BSS)보다 압축강도는 최대 9%, 최대내력은 1~6%, 연성능력은 각각 1.02~1.13배 증가하는 결과를 나타내었다. 또한, 충분한 연성적인 거동과 안정적인 휨인장 파괴를 나타내었다.