• The Journal of Advanced Prosthodontics
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• 제7권3호
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• pp.214-223
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• 2015

PURPOSE. To measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes. MATERIALS AND METHODS. Three hundred zirconia bars were randomly divided into 25 groups according to the type of sandblasting performed with pressures of 0.1, 0.2, 0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds, and alumina powder sizes of 50 and $110{\mu}m$. The control group did not receive sandblasting. The volume loss and height loss on zirconia surface after sandblasting and the shear bond strength (SBS) between the sandblasted zirconia and ICR after 24-h immersion were measured for each group using multivariate analysis of variance (ANOVA) and Least Significance Difference (LSD) test (${\alpha}$=.05). After sandblasting, the failure modes of the ICR/zirconia surfaces were observed using scanning electron microscopy. RESULTS. The volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from $50{\mu}m$ to $110{\mu}m$. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength. CONCLUSION. Based on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of $110{\mu}m$ is recommended for dental applications to improve the bonding between zirconia core and ICR.

• 한국자기학회지
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• 제18권5호
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• pp.195-199
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• 2008

$Fe_{93.5}Si_{6.5}$ 분말/에폭시 복합재 필름은 열경화과정을 이용하여 준비되었다. 자성분말/에폭시 복합재의 구조와 전자기적 특성 및 전자파 흡수특성을 분석하기 위하여 주사전자현미경(scanning electron microscpoe, SEM), 시료진동형 자력계(vibrating sample magnetometer, VSM), 네트워크 어날라이져(network analyzer) 등을 이용하였다. 분석결과, 포화자속밀도는 복합재 내의 $Fe_{93.5}Si_{6.5}$ 분말이 차지하는 양에 의존하며, 이는 초기투자율에 영향을 미친다. 결과적으로 1 GHz 이상의 주파수에서는 와전류 손실(eddy current loss)이 주요한 인자이며, 자성분말/에폭시 복합재의 공명주파수(resonance frequency)는 복합재 내의 $Fe_{93.5}Si_{6.5}$ 분말의 양이 증가함에 따라 감소한다. 반사손실(reflection loss)은 자성분말/에폭시 복합재의 투자율(permeability)과 유전율(permittivity)로부터 계산에 의해 구해진다. 50 wt% $Fe_{93.5}Si_{6.5}$ 분말의 양과 5 mm 두께를 가진 자성분말/에폭시 복합재는 3.66 GHz와 4.16 GHz 사이에서 -20 dB 이하의 값을 보인다. 따라서 Fe-Si/에폭시 박형 복합재는 마이크로파 흡수체로서 좋은 후보물질이 될 수 있을 것으로 판단된다.

• 한국전기전자재료학회논문지
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• 제27권7호
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• pp.462-467
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• 2014

In this paper, we studied the magnetic composite sheets for electromagnetic wave noise absorber of quasi-microwave band by using soft magnetic FeSiCr and Fe50Ni flakes with the thickness of about $1{\mu}m$ and polymer. The magnetic hysteresis curve including saturation magnetization and residual magnetization and the complex permeability characteristics of the composite sheets were investigated to clarify the mixing effect on electromagnetic wave absorption properties. The saturation magnetization was decreased about 10% while the residual magnetization was increased about 15% and the real parts of complex permeability at below 500 MHz were increased 0.6~4 while those values at above 500 MHz were decreased 0.4~2.5 according to the change of contents of FeSiCr and Fe50Ni powders. As a result, the reflection loss can be moved to the lower frequency from 2~3 GHz to 1~1.5 GHz as the contents of Fe50Ni flaky powder into FeSiCr flaky powder was increased up to 50%.

• 한국자기학회지
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• 제8권3호
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• pp.125-130
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• 1998

13Cr-1.5Nb-Fe합금분말이 수분사법으로 제조되엇다. 제조된 합금뷴말을 압축기를 이용하여 ring현상으로 성형한후, 진공중에서 소결하였다. as-prepared 분말의 현상, 입도분포, 성분분석 및 포화자화물 조사하였으며, 소결된 시편의 투자율, 교류자기이력손실이 조사되었다. as-prepared 13Cr-1.5Nb-Fe합금분말의 포화자화는 160emu/g이었으며, 산소함유량은 약 600ppm이었다. 입도분포는 약 70$\mu$m에서 50%vol.을 나타낸다. 교류투자율은 소결온도 및 성형온도가 증가할수록 증가한다. 주파수 20KHz에서 교류자기이력손실은 12ton/cm2성령압력 및 120$0^{\circ}C$ 소결온도 조건에서 107W/cc로 가장우수하다.

• Journal of Magnetics
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• 제21권2호
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• pp.192-196
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• 2016

The Fe-Si-B-Nb-Cu alloys containing Ca and Al were rapidly solidified to thin ribbons by melt-spinning. The ribbons were ball-milled to make powders, and then mixed with 1 wt.% water glass and 1.5 wt.% lubricant. The mixed powders were burn-off, and then compacted to form toroidal-shaped cores, which were heat treated to crystallize the nano-grain structure and to remove residual stress of material. The characteristics of the powder cores were analyzed using a differential scanning calorimetry (DSC) and a B-H meter. The microstructures were observed using transmission electron microscope (TEM). The optimized soft magnetic properties (${\mu}_i$ and $P_{cv}$) of the powder cores were obtained from the Ca and Al containing alloys after annealing at $530^{\circ}C$ for 1 h. The core loss of Fe-Si-B-Nb-Cu-based powder cores was reduced by the addition of Ca element, and the initial permeability increased due to the addition of Al element.

• 한국식품조리과학회지
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• 제28권6호
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• pp.839-846
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• 2012

This study was carried out in order to evaluate the effects of paprika powder on bread quality. Breads were prepared with the addition of 0%, 2.5%, 5.0%, 7.5% and 10.0% of paprika powder based on wheat flour. The weight of breads with paprika powder ranged from 526.5~537.3 g; that of the control was 525.0 g. The volume of the breads prepared by adding paprika powder was 1946.1~2114.3 mL, whereas that of the control was 2144.4 mL. The height, specific volume and baking loss rate of breads with added paprika powder decreased with the addition of paprika powder. The hardness, springiness, cohesiveness and chewiness increased with the addition of paprika powder. The Hunter L values of breads decreased, whereas a and b values increased. The sensory quality of the paprika powder breads tested by color, moistness and chewiness was better than that of the control. In particular, the overall acceptability of the bread with the addition of 5.0% paprika powder had the best quality.

• 한국식생활문화학회지
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• 제31권5호
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• pp.498-505
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• 2016

This study investigated grape powder substituted for wheat flour in muffin recipes with the amounts of 0, 5, 10, 15, and 20%. Grape powder consisted of 6.76% of moisture content, 4.63% of crude protein, 4.82% of crude fat and 4.16% of crude ash. DPPH radical scavenging activity is 68.79%, total phenol content is 205.79. Specific loaf volume have decreased as the grape powder content increased. Baking loss have increased as the grape powder content increased. Moisture and brix have increased as the grape powder content increased. pH have increased as the grape powder content decreased. Chromaticity measurement result showed that the 'L' and 'b' value of muffins decreased as grape powder content increased, whereas 'a' value increased. The texture measurement result showed that the hardness, gumminess and chewiness of muffins increased as the grape powder content increased, whereas springiness decreased. Cohesiveness did not show any considerable differences between muffins. Overall preference scores showed high overall acceptability for the muffins made with 10% grape powder.

• 동아시아식생활학회지
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• 제20권6호
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• pp.909-915
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• 2010

In order to determine the most effective ratio of black soybean powder as an ingredient in cake, black soybean power was added at ratio of 10, 20, 30, and 40% versus wheat flour set as 0(control). Black soybean powder consisted of moisture(8.44%), crude protein(31.34%), crude fat(6.64%), crude ash(3.88%) and carbohydrates(49.70%). The specific gravity, spreadability, and baking loss increased according to the amount of black soybean powder, although specific volume decreased. The chromaticity 'L' and 'b' values of sponge cake with black soybean powder showed an reducing trend while the 'a' value displayed an increasing trend with an increase in black soybean powder. The texture properties of sponge cake with added black soybean powder showed an increasing trend in hardness and stiffness when the cake contained more black soybean powder. The sensory test for sponge cake with added black soybean powder showed high preference for 20% added black soybean powder to sponge cake.

• 동아시아식생활학회지
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• 제24권5호
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• pp.621-630
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• 2014

This study presents the quality characteristics of blueberry bread. Blueberry fruit powder was added to bread dough at various concentrations ranging from 3~9%, after which physicochemical properties of dough and bread containing blueberry fruit powder were determined. The pH, loaf volume, specific loaf volume, dough volume and baking loss decreased with increasing amount of blueberry fruit powder in bread, whereas loaf weight and hardness were reduced. In particular, hardness appeared to be 1.98 times higher in the control without blueberry powder compared to the bread containing 9% blueberry powder. For color, increasing the amount of blueberry fruit powder reduced L and b values, whereas a value was increased. In the sensory evaluation, the highest overall preference score was observed in bread containing 6% blueberry powder, whereas the lowest score was observed in bread with 9% blueberry powder. From these results, blueberry bread with good acceptability has an optimum blueberry powder concentration of 6%.

• 동아시아식생활학회지
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• 제18권5호
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• pp.781-788
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• 2008

This study was conducted to investigate the quality of white pan breads as affected by various concentration of Cordyceps powder. Breads were prepared by addition of 0, 1, 2 and 3% of Cordyceps to flour of basic formulation. The moisture content of white pan breads decreased with increasing Cordyceps powder concentration. The pH of white pan breads also decreased with increasing Cordyceps powder concentration. In color values, with increase of Cordyceps powder concentration, L value decreased and a value increased in the crumb. The weights of breads cooled decreased with increasing Cordyceps powder concentration. The volume and height of dough decreased with increasing Cordyceps powder concentration. However, the specific volume and yield of dough were not significantly different among groups. The baking loss rate was higher in the breads with Cordyceps powder than in the control. In the texture characteristics, hardness and chewiness of breads significantly increased with increasing Cordyceps powder concentration and adhesiveness increased. In the sensory evaluation, when compared to the control, the breads added to 1% of Cordyceps powder was superior to in color and flavor, while was similar to texture and taste.