• Composites Research
• /
• v.37 no.3
• /
• pp.186-189
• /
• 2024

This study compared and evaluated the mechanical properties of carbon fiber reinforced thermoplastic polymer (CFRTP) mixed with nanofillers. After mixing various nanofillers such as Multi-wall carbon nanotube (MWCNT), Silicon oxide, Core shell rubber, and Aramid nanofiber with Polyamide 6 (PA6) resin, this is used as a matrix to create a carbon fiber reinforced composite material (CFRP) was manufactured and its physical properties were measured. Depending on the type and mixing ratio of nanofiller, tensile strength, inter-laminar shear strength (ILSS), and Izod impact strength were measured. In terms of tensile strength and impact strength, the highest values were obtained when mixing core shell rubber, however the ILSS was optimal when mixing less than 1 wt.% of silicon oxide.

• Composites Research
• /
• v.37 no.3
• /
• pp.197-203
• /
• 2024

Mechanical, electrical and thermal properties of polymer composites can be improved simultaneously by incorporating carbon fibers (CFs), which are beneficial for improving the mechanical properties, and multi-walled carbon nanotubes (MWCNTs), which are advantageous for improving the conductive properties. In this study, MWCNTs were incorporated into carbon long fiber thermoplastic (CLFT), which has excellent mass production processability and excellent mechanical properties, to control electrical and thermal properties. The mechanical and electrical properties of the prepared composites were most significantly influenced by the amount of filler incorporated. On the other hand, the thermal properties were improved due to the formation of a filler network interconnected by the incorporation of MWCNTs. By adjusting the filler amount, filler composition, and filler network structure of MWCNT-incorporated CLFT, the mechanical, electrical, and thermal properties could be controlled.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.36 no.1
• /
• pp.62-70
• /
• 2009

The objective of this study was to measure the leaching of filler (Si, Ba) from nanofiller-contained composites (Palfique Estelite $sigma^{{R}}$ (Tokuyama Dental Corp., Tokyo, Japan), $Z-350^{{R}}$ (3M ESPE, USA), Ceram X duo $E3^{{R}}$, $D3^{{R}}$ (Dentsply, Konstanz, Germany)) under different conditions. The samples used for the study of leachable components were made by insertion of the material into a circular mold, 10 mm in diameter and 3.0 mm high. Each specimen was placed in a disposable polystyrene vial containing 5 mL of distilled water, artificial saliva or 0.1N NaOH and kept in an oven at $37^{\circ}C$. ; water and artificial saliva - 150 days, 0.1N NaOH - 15days. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine the amount of Si and Ba in the test solutions. 1. Filler leaching was significantly great in 0.1N NaOH among all samples(p<.0.001). 2. When samples were stored in the distilled water, Estelite showed the lowest amount of Si leaching. When samples were stored in the artificial saliva, Z-350 showed the lowest amount of Si leaching. 3. There were significant differences in filler leaching between 3 storage medias and composite resins(p<.0.001). 4. Si and Ba leaching occurred in greater proportion when samples were stored in the artificial saliva than distilled water. 5. There were significant interactions in monthly filler leaching between leaching in artificial saliva and in distilled water, as well as the interaction between storage medium and filler(p<.0001). These results indicate that a continuous filler leaching of nanofiller-contained composite resins was in storing aqueous solutions under over time.

• Proceedings of the KWS Conference
• /
• 2007.11a
• /
• pp.248-250
• /
• 2007

이 연구는 cBN과 활성 Ag계 금속필러메탈을 이용하여 접합계면에서의 금속성분과 화합물, 탄화물의 거동을 분석하는데 있다. 진공 브레이징은 $900{\sim}1000^{\circ}C$에서 $25^{\circ}C$ 간격으로, 유지 시간은 각각 5, 10, 15, 20분으로 실시하였다. Ag-Cu-Ti을 사용하여 브레이징된 cBN은 $950{\sim}1000$도, 유지시간 10분 사이에서 각각 건전한 계면과 표면을 얻을 수 있었으며, 계면에서 Ti-rich상과 화합물이 확인되었다. 이상의 결과로 부터 화합물의 생성과 건전한 접합공정은 브레이징 온도와 시간이 좌우하며, N과 B, Ti의 함유량이 cBN의 브레이징 접합 특성의 중요변수로 생각되어진다. cBN과 Ag계 브레이징 필러의 계면에서의 미세조직 및 화학반응의 메커니즘은 DTA, SEM, EPMA, XRD를 이용하여 분석하였다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.07b
• /
• pp.856-858
• /
• 2005

음성인식 시스템에서 입력된 음성 데이터에 대해 비인식 대상을 거부하는 기능은 신뢰도 보장 측면에 있어서 상당히 중요하며, 신뢰도를 높이기 위해서는 단순한 인식기능 외에 부적절한 입력 패턴의 거부 기능이 필요하다. 본 논문에서는 이러한 신뢰성 문제를 해결하기 위하여 음소기반 인식 네트워크에서 필러 모델 방법과 단어 검출률 방법을 사용하여 실험하였고, 문장의 단어 수에 따른 두 방법의 문장 거부 성능을 FAR과 FRR의 평균을 최소화 하는 값을 각각 구함으로써 비교${\cdot}$분석 하였다. 그 결과 필러모델 방법이 좀 더 나은 거부 성능을 보였고, 단어 검출률을 이용하는 방법이 인식 네트워크를 전부 거치지 않아도 되므로 실행속도와 메모리 절약에서 효과적이었다.

• Journal of Korea Multimedia Society
• /
• v.15 no.1
• /
• pp.32-39
• /
• 2012

In this paper, the implementation of location based services (LBS) using S-DMB (satellite-digital multimedia broadcasting) system was proposed. In S-DMB System, the frequency of transmitted signal is about 2 GHz which has a characteristics of strong straightness but weak diffraction so that there are many shade areas such as indoors and underground spaces. Therefore the signal transmitted from the satellite should be retransmitted by the earth repeaters called as gap filler. Because each gap filler has its own identification value, the gap filler ID introduces the area in which the gap filler was installed. Generally, the 51st data symbols of S-DMB pilot signal transmitted from the satellite are padded by dummy value and gap filler ID is embedded in this pilot symbol by the gap filler when S-DMB signals are retransmitted by gap fillers. So using gap filler ID of S-DMB system, LBS such as region registration, distance and time to destination, alarm of local area information could be implemented. In the experiment to prove the performance of the proposed LBS system using the gap filler ID of the S-DMB system, the firmware of S-DMB chip composing of RF and baseband parts was lightly modified so that application processor was able to manipulate the gap filler ID and the its related regional information.

• Korean Chemical Engineering Research
• /
• v.49 no.4
• /
• pp.465-469
• /
• 2011

In this study, poly(ethyleneoxide) and poly(ethylene imine) polymer blends containing fumed silica fillers were studied in order to enhance the ion conductivity and interfacial properties. Lithium perchlorate ($LiClO_4$) as a salt, and silica($SiO_2$) as the inorganic filler were introduced into the polymer composite electrolyte composites and the composites were examined to evaluate their ionic conductivity for a possibility test of electrolyte application. As the diameter of semicircle in an impedance test became smaller, ionic conductivity of composite electrolytes had been enhanced by addition of 20 wt% silica filler. However, the conductivity was not greatly changed over 20 wt% content because the silica was sufficiently saturated in the polymer electrolytes. Diffraction peaks of PEO became weaker with the addition of inorganic fillers using XRD analysis. It showed that a crystallinity was proportionally reduced by increasing filler contents. The morphology of composite electrolyte films has been investigated by SEM. The heterogeneous morphology which silica was evenly dispersed by the strong adhesion of PEI was shown at higher contents of silica.

• Journal of the Microelectronics and Packaging Society
• /
• v.24 no.2
• /
• pp.11-15
• /
• 2017

As the heat dissipation problem is increased in 3D multi flip chip packages, an improvement of thermal conductivity in bonding interfaces is required. In this study, the effect of alumina filler addition was investigated in non-conductive paste(NCP). The fine alumina filler having average particles size of 400 nm for the fine pitch interconnection was used. As the alumina filler content was increased from 0 to 60 wt%, the thermal conductivity of the cured product was increased up to 0.654 W/mK at 60 wt%. It was higher value than 0.501 W/mK which was reported for the same amount of silica. It was also found out that the addition of fine sized alumina filler resulted in the smaller decrease in thermal conductivity than the larger sized particles. The viscosity of NCP with alumina addition was increased sharply at the level of 40 wt%. It was due to the increase of the interaction between the filler particles according to the finer particle size. In order to achieve the appropriate viscosity and excellent thermal conductivity with fine alumina fillers, the highly efficient dispersion process was considered to be important.

• Journal of the Microelectronics and Packaging Society
• /
• v.26 no.4
• /
• pp.33-37
• /
• 2019

In this study, the graded thermal properties of composites are obtained by difference in specific gravity of fillers including Cu, h-BN and GO powders in epoxy. Relatively heavy powders such as Cu and h-BN compared to GO mostly at the bottom layer, while light GO powders were dispersed in the top layer in the composites. The thermal conductivity of composites was gradually increased from 0.55 (0.52) W/mK to 2.82 (1.37) W/mK for GO/h-BN (GO/Cu) epoxy composites from surface to bottom. On the contrary, the coefficient of thermal expansion was decreased from 51 ppm/℃ to 23 ppm/℃ and from 57 ppm/℃ to 32 ppm/℃ for GO/Cu and GO/h-BN, respectively. The variation of thermal properties in composites is attributed due to intrinsic material properties of filler including thermal conductivity, morphology and the distribution by the specific weight of fillers. This simple strategy for realizing graded thermal composites by introducing different filler materials would be effective heat transfer at interface of heterostructure with large thermal properties such as inorganic semiconductor/plastic, metal/plastic, and semiconductor/metal.

• Composites Research
• /
• v.34 no.5
• /
• pp.290-295
• /
• 2021

The application of lightweight structural composites to automobiles as a solution in line with global fuel economy regulations to curb global warming is recognized as a megatrend. This study was conducted to provide a technical approach that can respond to the issue of replacing parts that require conductive properties to maximize the application of thermoplastic carbon fiber reinforced plastics (CFRPs), which are advantageous in terms of repair, disposal and recycling. By utilizing the properties of the low-viscosity polymerizable oligomer matrix, it was possible to prepare a thermoplastic CFRP exhibiting excellent impregnation properties while uniformly mixing the conductive filler. Various carbon-based conductive fillers such as carbon black, carbon nanotubes, graphene nanoplatelets, graphite, and pitch-based carbon fibers were filled up to the maximum content, and electrical and thermal conductive properties of the fabricated composites were compared and studied. It was confirmed that the maximum incorporation of filler was the most important factor to control the conductive properties of the composites rather than the type or shape of the conductive carbon filler. Experimental results were observed in which it might be advantageous to apply a one-dimensional conductive carbon filler to improve electrical conductivity, whereas it might be advantageous to apply a two-dimensional conductive carbon filler to improve thermal conductivity. The results of this study can provide potential insight into the optimization of structural design for controlling the conductive properties of thermoplastic CFRPs.