• 한국세라믹학회지
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• 제56권2호
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• pp.205-210
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• 2019

Bioactive glass (BG) finds limited use as a bone replacement material owing to its low mechanical properties. In order to solve this problem, the micro-sized 13-93 BG was prepared as a fabric composite with SiC microfibers, and its mechanical properties and biocompatibility were investigated in this study. The tensile strengths of BG-SiC fiber-bundle composites increased in proportion to the number of SiC fibers. In particular, even when only one SiC fiber was substituted, the tensile strength increased by 81% to 1428 MPa. In the early stage of the in-vitro test, a silica-rich layer was formed on the surface of the 13-93 BG fibers. With time, calcium phosphate grew on the silica-rich layer and the BG fibers were delaminated. On the other hand, no products were observed on the SiC fibers for 7 days, therefore, SiC fibers are expected to maintain their strength even after transplantation in the body.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.91-96
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• 2000

Glass fiber reinforced thermoplastic composites were manufactured by Rapid Press Consolidation Technique(RPCT) as functions of temperature, pressure and time in pre-heating, consolidation and solidification sections during the manufacturing processing. It was found that the material property is greatly affected by pre-heating temperature under vacuum, mold temperature and molding pressure. Among them, the temperature In the mold was the most critical factor in determining the mechanical properties and the molded conditions of specimen. The crystallinity of PET matrix was also investigated by differential scanning calorimetry(DSC) measurements for various processing conditions. The level of crystallinity($X_c$) depended strongly on the mold temperature, cooling rate and the type of composite. The difference in $X_c$ is believed to be one of important factors in characterizing the mechanical properties.

• 한국세라믹학회지
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• 제37권8호
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• pp.805-810
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• 2000

The formation, microstructure and properties of MoSi2/SiC ceramic composites by polymer pyrolysis were investigated for the application of heating element material. Polymethylsiloxanes were mixed with Si, SiC, MoSi2 as filler and ceramic composites prepared by pyrolysis in N2 atmosphere at 1320~145$0^{\circ}C$ were studied. Dimensional change, density variation and phases were analyzed and correlated to the resulting material properties. Microstructures of ceramic composite prepared by polymer pyrolysis were composed of MoSi2, SiC and silicon oxycarbide glass matrix. Depending on the pyrolysis conditions, ceramic composites with a density of 86~90 TD%, a fracture strength of 213~284 MPa, a thermal expansion coefficient of 4~7$\times$10-6 were obtained. The electrical resistivity of the specimen decreased with increasing of temperature up to 50$0^{\circ}C$.

• 한국세라믹학회지
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• 제49권1호
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• pp.100-104
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• 2012

Barium zincoborate (BZB) glass was added to $Ba_{0.5}Sr_{0.5}TiO_3$, and sintered at $875^{\circ}C$ for 2 h in air. When the BZB glass was added in quantities ranging from 15 to 20 wt%, the relative bulk density ranged from 93.1% to 94.2%, while the density decreased to roughly 81% thereafter up to 30 wt% glass addition. Quantitative XRD analysis showed that the $Ba_{0.5}Sr_{0.5}TiO_3$ filler was significantly dissolved into the BZB glass. However, no secondary phase was identified by XRD up to 30 wt% glass addition. The dielectric constant was about 130 to 140 at 1MHz up to 20 wt% BZB glass addition, while it decreased to about 60 thereafter, which may be ascribed to decreased density, partial dissolution of the $Ba_{0.5}Sr_{0.5}TiO_3$, and associated changes in the glass composition. The dielectric loss of the 20 wt% glass added specimen was 0.008.

• 동력기계공학회지
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• 제9권4호
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• pp.137-142
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• 2005

The effects of temperature and initial crack length on impact fracture behavior of side plate material of 35 ton class FRP ship, which are composed by glass fiber and unsaturated polyester resin, were investigated. Impact fracture toughness of GF/PE composites displayed maximum value when the temperature of specimen is room temperature and $50^{\circ}C$, and with decrease in temperature of specimen, impact fracture toughness decreased. Impact fracture energy of GF/EP composites decreased with increase in initial crack length of specimen, and this value decreased rapidly when the temperature of specimen is lowest, $-25^{\circ}C$,. It is believed that sensitivity of notch on impact fracture energy were increased with decrease in temperature of specimen. As the GF/EP composites exposed in low temperature, impact fracture toughness of composites decreased gradually owing to the decrease of interface bonding strength caused by difference of thermal expansion coefficient between the glass fiber/polyester resin. Further, decrease of interface bonding strength of composites with decrease in specimen temperature was ascertained by SEM photograph of impact fracture surface.

• 한국결정성장학회지
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• 제6권3호
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• pp.439-448
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• 1996

광투과성 BK10 glass fiber/PMMA 복합재료의 합성조건을 변화시켜 복합재료가 온도와 파장을 감지하는 센서로서의 응용 가능성이 있는지를 연구하였다. 유리섬유 제조시 뽑아내는 속도와 온도등의 공정조건에 따른 유리섬유의 직경 및 굴저율을 측정하였고 유리섬유에 코팅되는 coupling agent의 용매 및 코팅방법에 대하여 연구하였다. 복합재료의 최대광투과도를 나타내는 온도($T_{max%}$)는 복합재료에 강화되는 유리섬유의 크기(굴정율), 유리섬유 vol%, PMMA의 분자량등을 변화시키면 $13~50^{\circ}C$ 범위에서 조정될 수 있었으며, 측정파장을 변화시킬 경우 $T_{max%}$ 값이 $35~55^{\circ}C$ 범위가 되도록 합성하는 것이 가능하였다. 한편 복합재료를 파장의 함수로서 광투과도를 측정하였을 때 최대광투과도가 나타나는 파장($\lamda_{max%}$)은 나타나지 않았다.

• 대한치과기공학회지
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• 제25권1호
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• pp.21-28
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• 2003

The purpose of this study was to process bio-active glass ceramic composite, reinforced with sapphire fibers, by hot press. Also to study the interface of the matrix and the sapphire fiber, and the mechanical properties. Glass raw materials melted in Pt crucible at 1300$^{\circ}C$ during 3.5 hours. The melt was crushed in ball mill and then crushed material, ground and sieved to $<40{\beta}{\mu}m$. Sapphire fibers cut (30mm) and aligned. Powder and fibers hot pressed. The micrographs show good bonding between the matrix and the fiber and no porosity in the glass matrix. This means ideal fracture phenomena. Glass is fractured before the fiber. This is indication of good fracture strength. EDXS showing aluminum rich phase and crystalline phase. Bright field image of the matrix showing crystalline phase. Also diffraction pattern of TEM showing the crystalline phase and more than one phase. Strength of the samples was determined by 3 point bend testing. Strength of the 10vol% sample was approximately 69MPa, while strength of the control sample is 35MPa. Conclusions through this study as follow: 1. Micrographs show no porosity in the glass matrix and the interface. 2. The interface between the fiber and the glass matrix show no gaps. 3. Fracture of the glass indicates characteristic fiber-matrix separation. 4. Presence of crystalline phase at high processing temperature. 5. Sapphire is compatible with bioactive glass.

• 수산해양기술연구
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• 제47권3호
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• pp.267-272
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• 2011

The behavior of abrasive wear on counterpart roughness of glass fiber reinforcement polyurethane resin (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The friction coefficient, cumulative wear volume and surface roughness of these materials against SiC abrasive paper were determined experimentally. The major failure mechanisms were lapping layers, ploughing, delamination, deformation of resin and cracking by scanning electric microscopy (SEM) photograph of the tested surface. As increasing the counterpart roughness the GF/PUR composites indicated higher friction coefficient. The surface roughness of the GF/PUR composites was increased as the sliding velocity was higher and the counterpart roughness was rougher in wear test.

• 수산해양기술연구
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• 제46권4호
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• pp.495-502
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• 2010

The effect of load and sliding speed on abrasive wear characteristics of glass fiber/polyurethane (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The friction coefficient, cumulative wear volume and surface roughness of these materials against SiC abrasive paper were determined experimentally. Experimental results showed that the surface roughness of the GF/PUR composites was increased as applied load was higher in wear test. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on applied load and sliding speed for these composites. It could be verified by scanning electric microscopy (SEM) photograph of surface tested that major failure mechanisms were lapping layers, ploughing, delamination, deformation of resin and cracking.

• 한국안광학회지
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• 제6권1호
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• pp.145-148
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• 2001

안경렌즈 절삭용 재료의 파괴인성과 경도를 향상시키기 위하여 glass상을 함유한 탄화규소계 복합재료를 개발하여 그 기계적 물성과 특성을 연구하고자 하였다. glass상을 갖는 탄화규소를 $1810^{\circ}C$에서 2시간, 25 MPa의 조건에서 일축 가압소결 공정으로 안경렌즈 절삭용 시편을 제조하였다. 파괴인성과 경도를 측정하여 전에 실험한 결과의 기계적 특성과 비교하였다. 본 연구에서 연구된 안경렌즈 절삭용 시편의 대표적인 경도와 파괴인성은 각각 12 GPa과 $5.1MPa{\cdot}m^{1/2}$ 이었다.