• Journal of the Korean Wood Science and Technology
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• 제47권4호
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• pp.472-485
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• 2019

When wood plastic composites (WPCs) have been used for a certain period of time, they become waste materials and should be recycled to reduce their environmental impact. Waste WPCs can be transformed into reinforced composites, in which fillers are used to improve their performance. In this study, recycled WPCs were prepared using different proportions of waste WPCs, nanoclay, and glass fiber. The effects of nanoclay and glass fiber on the microstructural, mechanical, thermal, and water absorption properties of the recycled WPCs were investigated. X-ray diffraction showed that the nanoclay intercalates in the WPCs. Additionally, scanning electron micrographs revealed that the glass fiber is adequately dispersed. According to the analysis of mechanical properties, the simultaneous incorporation of nanoclay and glass fiber improved both tensile and flexural strengths. However, as the amount of fillers increases, their dispersion becomes limited and the tensile and flexural modulus were not further improved. The synergistic effect of nanoclay and glass fiber in recycled WPCs enhanced the thermal stability and crystallinity ($X_c$). Also, the presence of nanoclay improved the water absorption properties. The results suggested that recycled WPCs reinforced with nanoclay and glass fiber improved the deteriorated performance, showing the potential of recycled waste WPCs.

• 한국건설순환자원학회논문집
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• 제2권3호
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• pp.188-195
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• 2014

방호 방폭용 뿜칠형 고성능 섬유보강 시멘트 복합재료(HPFRCC) 개발을 위한 기초적인 연구의 일환으로 페이스트, 모르타르 및 HPFRCC 각 단계에서 구성재료의 레올로지 특성을 평가하였다. 페이스트 단계에서 레올로지 실험결과, GGBFs 및 FA의 경우 혼합률 증가에 따라 소섬정도 및 항복응력은 감소되는 것으로 나타났으며, SF의 경우 혼합률 10% 이후부터 소성점도 및 항복응력이 급격하게 증가되는 것으로 나타났다. 모르타르 단계에서 레올로지 실험결과, 잔골재의 종류 즉, 잔골재의 입형 및 입도는 소성점도 및 항복응력에 많은 영향을 미치는 것으로 나타났으며, Vs/Vm의 변화는 항복응력 보다 소성점도에 더 큰 영향을 미치는 것으로 나타났다. HPFRCC 단계에서 유동성 및 레올로지의 실험결과, 섬유 혼입 후 유동성 및 섬유분산성 개선에는 SP 보다 VA가 더 유효한 것으로 나타났다.

• 센서학회지
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• 제18권5호
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• pp.402-407
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• 2009

In this study, plastic optical fiber sensors which can measure thermal neutron dose in a mixed neutron-gamma field are developed and characterized. Using $^{252}Cf$ and $^{60}Co$ sources, the scintillators suitable for thermal neutron detection, are tested and the scintillating lights generated from a plastic optical fiber sensor in the Kyoto University Critical Assembly (kuca) core are measured. Also, the distributions of thermal neutron and gamma-ray are measured in a mixed field as a function of the distance from the center of the reactor core at KUCA and the distribution of thermal neutron is obtained using a subtraction method. Sensitivity of the fiber-optic radiation sensor system is about 0.49 V/mW according to power of the KUCA core and its relative error is about 1.2 %.

• 대한방사선기술학회지:방사선기술과학
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• 제28권1호
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• pp.9-12
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• 2005

본 연구에서는 엑스선 또는 감마선 원거리 측정용 초소형 방사선 센서를 개발하기 위해서 발광 스펙트럼이 다른 여러 종류의 무기 섬광체를 이용하여 필름형태의 센서부를 제작하였고, 방사선으로부터 발생되는 섬광량을 광검출기 및 광파워미터로 측정하였다. 본 연구 결과, 개발 가능한 방사선 센서는 직경 1 mm의 플라스틱 광섬유를 사용하여 전자기파 장애로부터 간섭을 받지 않음과 동시에 원거리 측정 및 신속, 정확한 방사선 계측이 가능하고 초소형, 초경량의 특성을 지니기 때문에 방사선 치료 시 고 분해능의 방사선 계측이 가능할 것으로 기대된다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.217-220
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• 2003

Due to the lighter weight and the higher freedom of design than metals plastics have been spot lighted in a wide number of applications. In the making plastic parts injection-molding process is one of the most general methods. During the injection molding process, filling-packing-cooling process, plastics have exposed to several external stresses and then plastic parts injected have molding effects which are known as anisotropic properties, orientation, and residual stress. Those molding effects are often shown as unexpected phenomena which are warpage, strength decrease, stiffness reduction, etc. In case of glass fiber filed plastics these effects are more significant than the ufilled ones. Therefore the molding effects have to be considered in the parts design using glass fiber reinforced plastics. We have developed the interface program in order to consider the molding effects in structural analyses of plastic parts using Heirarchical structural searching and layer handling in direction of thickness algorithm. The advantages of this program are the freedom of FE mesh between molding and structural analysis, the variable layer to the thickness direction of parts and the conveniences of data transferring and checking

• 한국전자파학회논문지
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• 제16권7호
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• pp.746-752
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• 2005

본 논문에서는 무선광 연결에서 신호광과 잡음광에 대한 플라스틱 광섬유의 손실차를 이용하여 잡음광의 영향을 감소하였다. 플라스틱 광섬유에서 신호광과 잡음광에 대한 손실계수가 달라서 차동검출기를 구성하는 2개의 포토다이오드로 연결되는 광섬유의 길이를 다르게 하면 신호광과 잡음광에 대한 감소 비율이 달라져 변별소자의 역할을 한다. 따라서 별도의 광필터를 설치하지 않아도 잡음광의 간섭을 소거하고 신호성분을 검출할 수 있다. 광섬유를 사용하지 않는 단일의 포토다이오드를 사용할 때에 비하여 광섬유를 사용할 때 약 9.7 dB신호대 잡음비를 개선하였다.

• 복합신소재구조학회 논문집
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• 제2권4호
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• pp.19-27
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• 2011

이 연구는 새로운 형태의 FRP-콘크리트 합성말뚝인 하이브리드 CFFT(HCFFT)를 개발하는 과정의 일부이다. 이 논문에서는 CFFT와 HCFFT의 압축강도실험을 통하여 구조적 거동을 분석하였다. 압축강도실험에 앞서 PFRP와 FFRP 재료의 역학적 성질을 조사하였다. HCFFT 압축강도실험은 콘크리트 강도와 FFRP의 두께를 변수로 하여 실험을 수행하였다. 그리고, FFRP 두께를 변수로 PFRP를 제외한 CFFT 실험체를 제작하고 실험을 수행하여 HCFFT와 비교 분석하였다. 실험 결과, HCFFT의 압축강도는 CFFT에 비하여 11~47% 향상되는 것으로 나타났다. 실험구간내의 필라멘트 와인딩 FRP 보강두께의 증가에 따른 HCFFT의 압축강도는 선형으로 증가시키는 것으로 나타났다. 또한 실험체와 동일한 조건의 유한요소해석을 수행하였다. 해석결과는 실험결과에 비하여 모든 시편에서 약간 작은 값을 보였으며, 0.14%에서 17.95%까지의 오차범위 내에 있음을 알 수 있었다.

• Journal of Welding and Joining
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• 제33권2호
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• pp.78-84
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• 2015

Self-piercing rivet(SPR) is mechanical joining methods and which can be joining dissimilar materials. Unlike conventional riveting, SPR also needs no pre-drilled holes. During plastically deformation, SPR pierces upper sheet and joins it to under sheet. SPR has been mainly applied to the joining the automobile body and some materials, such as glass fiber reinforced polymer and aluminum alloy, which represent the sheet-formed materials for lightweight automobile. Glass fiber reinforced plastic(GFRP) has been considered as a partial application of the automobile body which is lighter than steels and stronger than aluminium alloys. It is needed SPR to join Al alloy sheets and GFRP ones. In this paper, in order to design the rivet and anvil, which are suitable for GFRP, the joinability was examined through simulations of SPR joining between GFRP and Al alloy sheets. For this study, AutoCAD was used for the modeling and the simulated using commercial FEM code DEFORM-2D. The simulated results for SPR process joining between GFRP and Al alloys were confirmed by the same conditions as experimental trials.

• 한국항공운항학회지
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• 제18권4호
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• pp.51-58
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• 2010

Recently, aerospace structures have lightweight trend in order to reduce the cost of fuel and system, Carbon Fiber Reinforced Plastic (CFRP) can give the ability to reduce weight at 20~50% as the substitution of metal alloy, and there are advantages such as high Non-rigid, specific strength and anti-corrosion, but it is difficult to prove its destruction properties due to heterogeneous structure and anisotropy. In this study we designed specimen, inducing distinguishing destructions of material (for example, matrix crack, fiber breakage, and delamination) by using the Carbon Fiber Reinforced Plastic (CFRP) which is used in a real aircraft, to apply acoustic emission technique to aerospace structures. And we gained data via tensile testing and acoustic emission technique, from which each fault signal was classified respectively by using AE parameters and waveform.

• 센서학회지
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• 제25권3호
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• pp.208-212
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• 2016

In this work, a loop sensor for Arc-Flash detections has been developed in order to trip a circuit breaker within 2.5 ms after an Arc-Flash event. For an efficient capturing of the flash light, plastic optical fibers, where light attenuations are larger than those in silica-based ones, with different diameters and surface conditions were utilized. The performance was comparatively analyzed with those of a point sensor and a commercialized product. The point sensor module was designed for hemisphere-like capturings of Arc-Flashes larger than 3 kA at 2 meters from the sensor. On the other hand, the loop sensor allowed 360-degree-detections around the fiber axis and the measurement range was dependent on the length of the fiber connected to the sensor module. The trip-level-dependent brightness measurement results showed that the fabricated point sensor and loop sensor satisfied a brightness condition, 10~40 klux, and the responses of the system to Arc-Flashes were completed within 2.5 ms.