The purpose of this study was to investigate the microstructures and mechanical properties of zirconia toughened alumina (ZTA) ceramics prepared from two kinds of 3Y-TZP powders. ZTA composites were prepared by adding two kinds of 3Y-TZP powders, 3YEH (BET = 7m2/g) and 3YEM (BET = 16m2/g), to α-alumina in the range of 5-25 wt%. It was found that the microstructure photographs of the ZTA composites showed that the average grain size of alumina decreased as the content of zirconia increased. In our present study, specimens containing 3YEM zirconia exhibited smaller grain sizes compared to those of 3YEH zirconia. The Vickers hardness of the ZTA composites that were sintered at 1600˚C for 2 hrs was found to smoothly decrease with increasing zirconia content because of the low Young modulus in zirconia. The Vickers hardness of the ZTA containing 3YEH zirconia was greater than that of the 3YEM zirconia. In substance, the fracture toughness (K1c) of the ZTA composites increased as the content of zirconia increased. The fracture toughness (K1c) of ZTA containing 3YEM zirconia was greater than that of 3YEH zirconia.

연잎 및 연근분말을 우리밀가루 중량 100%를 기준하여 0.5, 1, 2 및 3%씩 첨가하여 제조한 우리밀식빵에 대한 반죽의 발효시간, 굽기 손실률, 식빵의 부피, 색도, 물성 및 관능검사 등 품질특성에 관하여 조사하였다. 연잎 및 연근분말을 첨가하여 제조한 반죽을 발효시간에 따른 부피 변화를 측정한 결과 발효시간이 경과함에 따라 반죽의 부피가 증가하는 경향을 나타내었으며 굽기 손실률 및 식빵의 부피는 연잎 및 연근분말의 첨가량이 증가함에 따라 감소하였다. 식빵의 crust와 crumb의 색도는 연잎 및 연근 분말의 첨가량이 증가함에 따라 밝기를 나타내는 L값은 감소하였으며, 적색도를 나타내는 a값은 crust, crumb 모두 유의적으로 증가하는 경향을 나타내었고, 황색도를 나타내는 b값의 경우 crust는 감소한 반면, crumb는 증가하는 것으로 나타났다. 연잎 및 연근분말을 첨가한 식빵의 조직감은 대조군과 비교하여 첨가량이 증가할수록 경도, 부착성, 검성 및 씹힘성은 증가되었으며, 관능검사를 실시한 결과 전체적인 기호도에서는 연잎분말 1%, 연근분말 2% 첨가한 시료에서 좋은 결과를 나타내었다.

투명 전도성 산화물로서 알루미늄과 붕소가 함께 도핑된 아연산화물(AZOB)이 900℃에서 분무 열분해법에 의해 제조되었다. 얻어진 마이크론 크기의 AZOB 분말은 알루미늄, 붕소 및 아연의 수용액으로부터 얻어진다. 분무 열분해로 얻어진 마이크론 크기의 AZOB 분말은 700℃에서 두 시간동안의 후 소성 과정과 24 시간 동안의 볼 밀링을 통해 나노 크기의 AZOB으로 변환된다. AZOB을 구성하는 일차 입자의 크기를 Debye-Scherrer 식에 의해 계산하였고 압축된 AZOB 펠렛의 표면 저항을 측정하였다.

마이크론 크기를 가지는 ITO(indium tin oxide) 입자들은 인듐과 틴의 수용성 전구체들과 유기 첨가제를 분무 열분해하여 얻었다. 유기 첨가제로서는 에틸렌글리콜과 시트르산을 이용하였다. 분무 열분해 시 에틸렌글리콜과 시트르산과 같은 유기첨가제를 첨가하지 않고 얻어진 ITO 입자들은 구형이며 속이 꽉찬 형태를 가지는데 비해 유기 첨가제를 첨가하여 분무 열분해를 하면 얻어지는 ITO 입자들은 유기 첨가제의 양이 증가 할수록 껍질이 얇고 다공성이 증대된 중공 입자가 얻어진다. 유기첨가제를 첨가하지 않고 분무 열분해를 통해 얻어지는 마이크론 크기를 가지는 ITO는 700℃에서 두 시간 동안의 후소성과 24 시간동안의 습식 볼밀링에 의해 나노 크기의 ITO로 전환되지 않으나, 유기첨가제를 첨가하고 분무 열분해를 통해 얻어지는 마이크론 크기를 가지는 ITO는 700℃에서 두 시간 동안의 후소성과 24 시간 동안의 습식 볼밀링에 의해 나노 크기의 ITO로 쉽게 전환되었다. 응집된 나노 크기의 ITO의 일차 입자의 크기를 Debye-Scherrer 식에 의해 계산하였고 ITO 입자를 압축하여 만든 펠렛의 표면저항을 측정하였다.

This study was performed to determine the optimal composition of muffins added with dropwort powder, egg and sugar. The experiment was designed based on BBD (Box-behnken design), and evaluation was carried out by means of RSM (response surface methodology), consisting of 13 experimental points with three replicates each for three independent variables dropwort powder, eggs and sugar. Using F-test, height, moisture, 1,1-diphenyl-2picriylhydrazyl (DPPH) radical scavenging activity, L-value, a-value, springiness, cohesiveness, chewiness, brittleness, color, and appearance acceptability were expressed as a linear model, whereas pH, b-value, flavor, taste, and texture were expressed as a quadratic model. After swallow and overall acceptability were expressed as a 2FI model. As dropwort powder content increased, 1,1-diphenyl-2picriylhydrazyl (DPPH) radical scavenging activity increased. Increasing amounts of dropwort powder led to reduction of sensory scores for color, appearance, flavor, taste, and texture quality. The optimum formulation determined by the numerical and graphical methods were similar: dropwort powder 6 g, egg 77 g, and sugar 60 g.

Al-Si-SiC composite powders with intra-granular SiC particles were prepared by a gas atomization process. The composite powders were mixed with Al-Zn-Mg alloy powders as a function of weight percent. Those mixture powders were compacted with the pressure of 700 MPa and then sintered at the temperature of 565-585˚C. T6 heat treatment was conducted to increase their mechanical properties by solid-solution precipitates. Each relative density according to the optimized sintering temperature of those powders were determined as 96% at 580˚C for Al-Zn-Mg powders (composition A), 97.9% at 575˚C for Al-Zn-Mg powders with 5 wt.% of Al-Si-SiC powders (composition B), and 98.2% at 570˚C for Al-Zn-Mg powders with 10 wt.% of Al-Si-SiC powders (composition C), respectively. Each hardness, tensile strength, and wear resistance test of those sintered samples was conducted. As the content of Al-Si-SiC powders increased, both hardness and tensile strength were decreased. However, wear resistance was increased by the increase of Al-Si-SiC powders. From these results, it was confirmed that Al-Si-SiC/Al-Zn-Mg composite could be highly densified by the sintering process, and thus the composite could have high wear resistance and tensile strength when the content of Al-Si-SiC composite powders were optimized.

Effect of oxygen content in the ultrafine tungsten powder fabricated by electrical explosion of wire method on the behvior of spark plasma sintering was investigated. The initial oxygen content of 6.5 wt% of as-fabricated tungsten powder was reduced to 2.3 and 0.7 wt% for the powders which were reduction-treated at 400˚C for 2 hour and at 500˚C for 1h in hydrogen atmosphere, respectively. The reduction-treated tungsten powders were spark-plasma sintered at 1200-1600˚C for 100-3600 sec. with applied pressure of 50 MPa under vacuum of 0.133 Pa. Maximun sindered density of 97% relative density was obtained under the condition of 1600˚C for 1h from the tungsten powder with 0.7 wt% oxygen. Sintering activation energy of 95.85kJ/mol-1 was obtained, which is remarkably smaller than the reported ones of 380~460kJ/mol-1 for pressureless sintering of micron-scale tungsten powders.

In this study, the reduction kinetics and behaviors of oxides in the water-atomized iron powder have been evaluated as a function of temperature ranging 850-1000˚C in hydrogen environment, and compared to the reduction behaviors of individual iron oxides including Fe2O3, Fe3O4 and FeO. The water-atomized iron powder contained a significant amount of iron oxides, mainly Fe3O4 and FeO, which were formed as a partially-continuous surface layer and an inner inclusion. During hydrogen reduction, a significant weight loss in the iron powder occurred in the initial stage of 10 min by the reduction of surface oxides, and then further reduction underwent slowly with increasing time. A higher temperature in the hydrogen reduction promoted a high purity of iron powder, but no significant change in the reduction occurred above 950˚C. Sequence reduction process by an alternating environment of hydrogen and inert gases effectively removed the oxide scale in the iron powder, which lowered reduction temperature and/or shortened reduction time.

In this research, magnesium powder was prepared by gas atomizing. Refinement behaviors of magnesium powder produced under different conditions were investigated using a mechanical milling (attrition milling) process. Analyses were performed to assess the characterization and comparison of milled powder with different steel ball sizes and milling times. The powders were analyzed by field emission scanning electron microscope, apparent density and powder fluidity. The particle morphology of the Mg powders changed from spherical particles of feed metals to irregular oval particles, then plate type particles, with an increasing milling time. Because of the HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, which results in producing plate-type powders. An increase in ball size and the impact energy of the magnesium powder maximizes the effect of refinement. Furthermore, it is possible to improve the apparent density and fluidity according to the smoothness of the surface of the initial powder.

본 연구에서는 유색감자 자영을 건조한 뒤 분쇄하여 분말을 제조하고 자영 분말을 전체 분말 기준으로 0, 30, 50,100% 첨가하여 쿠키를 제조한 후 쿠키의 총 페놀 함량,색도, 경도를 측정하고 관능 평가를 실시하였다. 쿠키의 총페놀 함량은 쿠키를 굽는 시간과 자영 분말 첨가량이 증가함에 따라 증가하였다. 쿠키의 색도는 색도차와 Browningindex로 나타내었다. 대조군인 밀가루 쿠키와의 색도차는자영 분말의 첨가량이 많을수록 컸으며, 쿠키를 굽는 시간이 증가할수록 감소하였다. Browning index의 경우 쿠키를굽는 시간이 증가할수록 전체적으로 증가하였다. 그 결과,logistic 모델이 유색감자 자영의 함량이 증가하였을 때 굽는 시간에 따른 갈변 현상을 나타내는 데 가장 적합함을알 수 있었다. 쿠키의 경도를 측정한 결과 6분 동안 구웠을 때 자영 분말의 함량이 증가할수록 경도가 증가하는 것을 확인하였으나 쿠키를 굽는 시간이 증가함에 따라 자영분말 첨가군 간의 유의차는 나타나지 않았다. 또한 쿠키를15분 이상 구웠을 때에는 대조군과 자영 분말 첨가 쿠키의 경도에 차이가 없었다. 관능 검사 결과는 자영 분말을30%와 50% 첨가한 쿠키를 11분간 구웠을 때 가장 높은 점수를 보이며 밀가루 쿠키와 유사한 기호도를 나타내었다.따라서 쿠키에 자영 분말을 첨가하여 11분에서 13분간 구웠을 때 시중에 유통되고 있는 높은 기호도의 밀가루 쿠키와 유사한 식감과 색도를 가지며, 항산화활성이 우수한 기능성 쿠키의 제조가 가능함을 확인하였다.

This study investigated the quality characteristics of cookies containing capsaicin, the main source of spicy taste in pepper, which is well known for its various functions such as anti-oxidant, anti-cancer, anti-inflammatory, and anti-obesity activities, as well as pain-relief effect. Cookie samples were made by adding the capsaicin powder at different levels, including 40 mg% (C1), 85 mg% (C2), and 150 mg% (C3). In this study, measurement of the moisture, pH, color, spread factor, hardness, anti-oxidant activity, and sensory evaluation of the cookies was carried out. The results showed that the anti-oxidant activity increased when more capsaicin powder was added to the cookies (p＜0.001). The moisture also increased with increasing capsaicin powder content (p＜0.05), while the pH did not show any significant changes. As for the colors, the L value and b value decreased as more capsaicin powder was added, while the a value increased. The spread factor also increased significantly with the increase of capsaicin powder (p＜0.01). Although the hardness increased with capsaicin powder content, no statistically significant differences were observed among the various cookies. In the sensory evaluation, Cookies containing 40 mg of capsaicin obtained the highest score in color, while cookies containing 150 mg of capsaicin showed the highest score in taste, texture, and overall acceptability.

The purpose of this study was to investigate the quality characteristics of white bean based Yanggaeng containing various levels of pomegranate powder (0, 2, 4 and 8%, w/w). The pH values of Yanggaeng containing pomegranate powder were found to decrease when increasing the amount of pomegranate powder. However, moisture and sugar contents were increased (p＜0.05). For color values, both L and b values were reduced by increasing the amount of pomegranate powder, while a values were increased significantly (p＜0.05). In textural properties, the addition of pomegranate powder resulted in the increase of hardness, chewiness and gumminess, while cohesiveness and springiness decreased. Antioxidant activities, evaluated by DPPH radical scavenging capacity, and total phenolic substances content increased when increasing the amount of pomegranate powder. Results of descriptive analysis showed that by increasing the amount of pomegranate powder, some attributes such as the intensity of the flavor, sourness, hardness and chewiness increased (p＜0.05), but there was no statistically significant difference in sweetness. In a preference test, Yanggaeng containing 4% pomegranate powder appeared to be the most preferred for all attributes tested including overall acceptability. It was concluded that Yanggaeng containing pomegranate can be prepared with good sensory properties and antioxidant activities, and the addition of 4% pomegranate powder was found to be ideal.

콩단백질을 이용한 콩고기 제조시 콩의 전처리 조건에 따른 품질 특성을 비교하고자 생콩, 증자콩 및 볶은콩 분말을 각각 동일 비율로 첨가한 콩고기의 품질관련 인자를 분석하였다. 관능평가 결과 생콩 분말로 제조한 콩고기의 기호도가 가장 낮았으나 견고성, 씹힘성 및 검성은 생콩으로 제조한 시료가 가장 높았다. L 값은 증자콩 분말로 제조한 콩고기에서 63.71±3.81로 가장 높았고, a값은 볶은콩분말로 제조한 콩고기에서 10.0±0.61, b값은 유사한 범위였다. 수분함량은 증자콩과 볶은콩 분말로 제조한 콩고기에서 유사한 범위이며 조지방은 증자콩 분말, 탄수화물은 생콩 분말로 각각 제조한 콩고기에서 가장 높았다. 아미노산의 총량은 생콩 분말로 제조한 콩고기가 89,863.79 mg/kg으로 가장 높았고, 지방산의 총량은 3916.9 mg/100g으로 증자콩 분말로 제조한 콩고기에서 가장 높았다. 총 flavonoids, isoflavone과 같은 생리활성 물질의 함량은 생콩 분말로 제조한 콩고기에서 가장 높았고, 항산화 활성은 증자콩으로 제조한 콩고기에서 더 높았다.

The quality characteristics of noodles made from domestic Korean wheat flour added with 0, 1, 3, 5% cactus Chounnyuncho (Opuntia humifusa) powder were investigated. The water absorption and peak time of dough, as determined by farinography, increased with higher cactus powder content. Stability and elasticity of dough decreased as fermentation proceeded. Cooking characteristics of noodles made from dough such as weight, water absorption, and volume decreased with higher cactus powder content. The turbidity of cooked water increased significantly with 5% cactus powder content. For color test, L-value decreased while a-value and b-value increased with higher cactus powder content. In texture analyses, hardness, adhesiveness, springiness, cohesiveness, and gumminess increased with higher cactus powder content. In the sensory test, noodles containing 3% cactus powder were the most preferred.