• Restorative Dentistry and Endodontics
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• 제14권1호
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• pp.25-40
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• 1989

This study was conducted to evaluate the influence of 5 microfilled composite resin to fibroblast cultivated from human pulp (age 13). Each composite resin was manually mixed and filled in cylinder. Resin filled cylinders were placed in dishes (35mm in diameter) containing 3 ml of ${\alpha}$-MEM. Filters (pore size 0.22 ${\mu}m$) to simulate dentin were also placed between the bottom of cylinder and the dish floor. Then stored in 5% $CO_2$ containing incubator for 1 and 2 weeks at the temperature 36.6 C. The results analysed after 1 and 2 weeks were as follows: 1. Experimental group except group 2, 2 weeks incubation cases showed the cytotoxicity compared to the control group in cell count. 2. After 2 week-incubation of group 1 and group 4, cell count was more decreased than 1 week cases and cytotoxicity seemed to be constantly influenced to the cell multiplication. 3. The cell growth rate of 1 week incubation in group 3 and group 5 was similar to the control group and recognized the cytotoxicities of these groups were mild. 4. The cell multiplication rate of 2 week incubation cases in group 2 was greater than control group.

• Journal of the Korean Wood Science and Technology
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• 제38권1호
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• pp.43-48
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• 2010

톱밥과 왕겨로 제조된 혼합보드로 세라믹을 제조한 후 수지함침율 및 소성온도에 따른 세라믹의 표면온도를 조사하였다. 경과시간 초기에 표면온도가 급상승 하였으며 수지함침율 60~70%와 소성온도 $1200^{\circ}C$로 제조된 세라믹의 표면온도가 가장 높았다. 히터의 표면온도보다 혼합세라믹의 표면온도 하강속도가 느려 혼합세라믹의 열 보존력이 높음을 알 수 있었다.

• Macromolecular Research
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• 제14권5호
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• pp.559-564
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• 2006

The improvement of spatial resolution is a fundamental issue in the two-photon, polymerization-based, laser writing. In this study, a voxel tuning method using a radical quencher was proposed to increase the resolution, and the quenching effect according to the amount of radical quencher was experimentally investigated. Employing the proposed method, the lateral resolution of the line patterns was improved almost to 100 nm. However, a shortcoming of the quenching effect was the low mechanical strength of polymerized structures due to their short chain lengths. Nano-indentation tests were conducted to evaluate quantitatively the relationship between mechanical strength and the mixture ratio of the radical quencher into the resins. The elastic modulus was dramatically reduced from an average value of 3.015 to 2.078 GPa when 5 wt% of radical quencher was mixed into the resin. Three-dimensional woodpile structures were fabricated to compare the strength between the resin containing radical quencher and the original resin.

• 대한화학회지
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• 제15권2호
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• pp.45-48
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• 1971

The various eluents have been used for the separations of alkaline earth metals by elutions through cation exchange resin column by many investigators. We find, the mixed solution of 1M HAc and 1M NaAc (pH 4.75) is the best eluent for this purpose, becouse the one step elution through 7cm Dowex 50w${\times}$8(100~200mesh) resin column with this eluent, gives the quantitative separation. When 2M NaAc is used as a eluent Sr(II) and Ba(II) is separated easily without any contamination of Mg(II) andCa(II). The Ca-Pb alloy which is composed of Cu, Ca, Sr, Ba and abundance of Pb metal is separated quantitatively into its components by the two step elution with 0.3M HAc + 0.3M NaAc(PH 4.75) and 0.5M HAc + 0.5M NaAc(PH 4.75) as eluents through 10cm resin column.

• 한국분말재료학회지
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• 제15권2호
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• pp.119-124
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• 2008

To increase pot life in the formulation mixed with bisphenol F epoxy resin, anhydride-based curing agent, and imidazole-based curing accelerator powders as a paste material for high-speed RFID chip bonding, size variation of the imidazole-based powders and a coating method of the powders were adopted in this study. In experiment with regard to the size variation, the pot life was not outstandingly increased. Through the idea using the coating method, however, the pot life was increased up to 4.25 times in comparison with the addition of initial imidazole-based powders. Consequently, successive bonding of RFID chip could be performed with very short time of 5sec using the suggested formulation having improved pot life.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.257-258
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• 2009

Nanocomposites of a epoxy resin are synthesized and evaluated the present study investigated. The effect of nanoclay additives on the properties of diglycidyl ether or bisphenol A(DGEBA) epoxy resin. DGEBA was mixed with 3~7 wt% organically modified layered silicate, Cloisite 30B for three hours. The average grain size of the specimens decreased with adding Cloisite 30B. The dielectric constant showed between 3.2 ~ 3.5 and the dielectric loss showed between 3.2 ~ 5.7 % in all specimens.

• Carbon letters
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• 제14권2호
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• pp.110-116
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• 2013

This study investigated a developed process for producing a composite bipolar plate having excellent conductivity by using coal tar pitch and phenol resin as binders. We used a pressing method to prepare a compact of graphite powder mixed with binders. Resistivity of the impregnated compact was observed as heat treatment temperature was increased. It was observed that pore sizes of the GCTP samples increased as the heat treatment temperature increased. There was not a great difference between the flexural strengths of GCTP-IM and CPR-IM as the heat treatment temperature was increased. The resistivity of GPR700-IM, heat treated at $700^{\circ}C$ using phenolic resin as a binder, was $4829{\mu}{\Omega}{\cdot}cm$ which was best value in this study. In addition, it is expected that with the appropriate selection of carbon powder and further optimization of process we can produce a composite bipolar plate which has excellent properties.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.257-260
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• 2005

Graphite reinforced conductive polymer composites were fabricated by the compression molding technique. Graphite powder was mixed with an phenol resin to impart electrical property in composites. The ratio and particle size of graphite powder were varied to investigate electrical conductivity of cured composites. In this study, graphite reinforced conductive polymer composites with high filler loadings(>66wt.%) were manufactured to accomplish high electrical conductivity. With increasing the loading ratio of graphite powder, the electrical conductivity and flexural strength increased. However. above 80wt.% filler loadings, flexural strength decreased due to lack of resin. Regardless of graphite particle size, electrical conductivity wasn’t varied. On the other hand, with decreasing particle size, flexural strength increased due to high specific surface area.

• 대한기계학회논문집A
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• 제32권9호
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• pp.788-795
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• 2008

To understand the tensile behaviors of GFRP at low temperature, three types of specimen have been used in this study. Tensile properties and fracture mechanisms for three orthogonal orientations of plain weave glass fabric reinforced epoxy resin laminate were investigated at temperature range of about -30 to $15^{\circ}C$. The tensile properties of axial and edge type specimen decrease slightly with decreasing temperature to $-20^{\circ}C$. However, at $-30^{\circ}C$ the decreases in the tensile properties increased considerably. Below $-20^{\circ}C$, thickness type specimen showed a marked decreases in the tensile properties. It was obvious that the fracture manner of thickness type specimen was adhesive failure at above $-10^{\circ}C$ and a mixed adhesive and cohesive failure at below $-20^{\circ}C$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1222-1223
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• 2008

Nanocomposites of a epoxy resin are synthesized and evaluated. the present study investigated the effect of nanoclay additives on the properties of diglycidyl ether or bisphenol A(DGEBA) epoxy resin. DGEBA was mixed with 3$\sim$7 wt% organically modified layered silicate, Cloisite 30B for three hours. The average grain size of the specimens decreased with adding Cloisite 30B. The dielectric constant showed between 3.2$\sim$3.5 and the dielectric loss showed between 3.2$\sim$5.7 % in all specimens. Dielectric strength showed a best valu of 20.8 kV/mm at added with Cloisite 30B 5 wt%.