• 한국식품과학회지
• /
• 제47권5호
• /
• pp.633-638
• /
• 2015

본 연구에서는 분무건조법을 이용하여 젖산세균을 녹말로 캡슐화한 분말을 제조하고, 제조한 젖산세균 코팅 분말을 이용하여 다양한 수분활성도에 따른 평형수분함량을 측정하여 등온흡습곡선을 확립하고, pH 및 상대습도, 온도에 따른 젖산세균의 보호 효과를 알아보고자 하였다. 젖산세균 코팅 분말의 등온흡습곡선은 수분활성도에 따라 평형수분함량이 빠르게 증가하는 sigmoid형을 나타내었으나 시료간의 유의적인 차이를 나타내지 않았다. 상대습도에 따라 20, 30, $40^{\circ}C$에서 저장하였을 때, 상대습도가 낮을수록, 저장 온도가 낮을수록 젖산세균의 생존율이 높았으며, 시료들 중 생강을 첨가하여 코팅한 젖산세균 분말의 생존율이 가장 높았다. 75%의 상대습도에서 $20^{\circ}C$와 $35^{\circ}C$에서 각 4주간 저장 실험한 결과, 코팅하지 않은 젖산세균은 1주 후 사멸한 반면, 코팅한 젖산세균은 유지되었으며 특히 생강을 첨가하였을 경우 젖산세균 보호 효과가 가장 높았다. 소화 모방 실험을 통해 위액의 낮은 pH에서 녹말 코팅의 보호막 효과를 확인하였다. 이를 통해 녹말로 코팅한 젖산세균 분말은 식품 조성물, 식품 첨가용 조성물로 이용 가능하다. 한편, 프로바이오틱스 제품 제조 시 젖산세균이 8-10 log CFU/g 이상 존재해야 하는데, 본 연구에서는 분무건조 후 약 7-8 log CFU/g로 다소 감소하였지만 이는 사료 조성물 또는 사료 첨가용 조성물로 응용이 가능하다고 생각된다.

• 한국산학기술학회논문지
• /
• 제21권10호
• /
• pp.206-211
• /
• 2020

텅스텐 합금은 일반 산업분야 뿐만 아니라, 방산 분야에서도 다양하게 활용되고 있다. 방산 분야에 활용되는 일반적인 합금의 제조 방법은 주조를 통하여 제조된 합금을 단조, 압연, 압출 등의 1차 가공 후 원소재로 공급하여 제품을 생산 한다. 하지만, 텅스텐 합금은 주조 공정에 어려움이 있어 분말야금법을 활용하여 제품을 제작하고 있다. 분말야금법은 미세한 분말을 이용하여 기계적 물성과 생산성을 높일 수 있으나, 양산 단계에서 제품 간 편차를 유발할 수 있다. 미세한 분말의 장점과 제품 간 편차를 감소하기 위하여 각 장점을 갖는 과립분말 제조에 대한 연구가 필요하다. 본 연구에서는 볼밀을 이용하여 균질화를 시킨 텅스텐과 니켈, 철의 혼합분말을 용매인 순수에 투입하고 결합제인 PVA를 첨가하여 분무건조용 혼합액을 제조하였다. 혼합액을 분무건조기를 이용하여 과립분말을 제조하였고, 분말야금법의 성형 및 소결 공정 중 제품 간 편차를 줄일 수 있는 과립분말의 제조를 목표로 연구를 수행하였다. 과립 공정에서는 다양한 변수(혼합물의 농도, 결합제의 용량, 분무건조기의 건조 온도, 분무 회전 속도) 간 영향성을 확인하기 위하여 예비 실험을 실시하였다. 예비 실험 결과를 통해 분무건조용 혼합물의 용매의 용량을 독립변수로 본 실험을 수행하였고, 기존 양산 조건과 유사한 평균 입도를 가지며, 겉보기 밀도가 증가한 개선된 과립분말을 제조하였다. 추가적으로 성형 및 소결 공정에 대한 파일럿 시험을 진행하여 개선된 과립분말이 양산 제품의 특성 편차(중량 편차)를 감소하는 것을 확인하였다.

• KEPCO Journal on Electric Power and Energy
• /
• 제2권2호
• /
• pp.285-291
• /
• 2016

In chemical-looping combustion, pure oxygen is transferred to fuel by solid particles called as oxygen carrier. Chemical-looping combustion process usually utilizes a circulating fluidized-bed process for fuel combustion and regeneration of the reduced oxygen carrier. The performance of an oxygen carrier varies with the active metal oxide and the raw support materials used. In this work, spraydried Mn-based oxygen carriers were prepared with different raw support materials and their physical properties and oxygen transfer performance were investigated to determine that the raw support materials used are suitable for spray-dried manganese oxide oxygen carrier. Oxygen carriers composed of 70 wt% $Mn_3O_4$ and 30 wt% support were produced using spray dryer. Two different types of $Al_2O_3$, ${\gamma}-Al_2O_3$ and ${\alpha}-Al_2O_3$, and $MgAl_2O_4$ were applied as starting raw support materials. The oxygen carrier prepared from ${\gamma}-Al_2O_3$ showed high mechanical strength stronger than commercial fluidization catalytic cracking catalyst at calcination temperatures below $1100^{\circ}C$, while the ones prepared from ${\alpha}-Al_2O_3$ and $MgAl_2O_4$ required higher calcination temperatures. Oxygen transfer capacity of the oxygen carrier prepared from ${\gamma}-Al_2O_3$ was less than 3 wt%. In comparison, oxygen carriers prepared from ${\alpha}-Al_2O_3$ and $MgAl_2O_4$ showed higher oxygen transfer capacity, around 3.4 and 4.4 wt%, respectively. Among the prepared Mn-based oxygen carriers, the one made from $MgAl_2O_4$ showed superior oxygen transfer performance in the chemical-looping combustion of $CH_4$, $H_2$, and CO. However, it required a high calcination temperature of $1400^{\circ}C$ to obtain strong mechnical strength. Therefore, further study to develop new support compositions is required to lower the calcination temperature without decline in the oxygen transfer performance.

• Journal of Pharmaceutical Investigation
• /
• 제32권3호
• /
• pp.191-197
• /
• 2002

Polymer based physical mixtures or solid dispersions containing solubilizing compositions[OA, tween80 and SLS] were prepared using a spray-dryer. Lovastatin(LOS), simvastatin(SIMS), aceclofenac(AFC) and cisapride(CSP) were selected as poorly water-soluble drugs. Dextrin, poly(vinylalcohol) (PVA), poly(vinylpyrrolidone)(PVP) and polyethylene glycol(PEG) were chosen as solubilizing carriers for solid dispersions. The solid dispersions containing solubilizing compositions without drug were prepared without using organic solvents or tedious changes of formulation compositions. This system could be used to quickly screen the dissolution profiles of poorly water-soluble drugs by simply mixing with drugs thereafter. In case of solid dispersion containing drug, organic solvent systems could be used to solubilize model drugs. The dissolution rates of the drugs were higher when mixed with drug and solid dispersions containing solubilizing compositions. However, solid dispersions of LOS, AFC, and CSP simultaneously containing drug and solubilizing compositions in organic solvent systems were more useful than physical mixtures of drug and solid dispersions without drug except SIMS. Based on solubilizing capability of polymer based physical mixtures in gelatin hard capsules, optimal solid dispersion system of poorly water-soluble drugs could be formulated. However, it should be noted that dissolution rate of poorly water-soluble drugs were highly dependent on drug properties, solubilizing compositions and polymeric carriers.

• Journal of Ginseng Research
• /
• 제24권1호
• /
• pp.23-28
• /
• 2000

덱스트린/에탄올/물(1/1/l, w/w/w)의 혼합용액에 라우릴황산나트륨 0.5%(w/w) 및 홍삼 엑기스 20%(w/w)를 첨가한 조성을 가지고 분무건조하여 제조한 분말 홍삼주는 최대 에탄올(31.17$\pm$ 1.33%(w/w)) 및 ginsenoside Rbl(243.0$\pm$ 7.0$\mu\textrm{g}$/g)이 봉입된 미립구로서 용해 및 복용감이 우수한 새로운 홍삼 엑기스의 제형으로서의 가능성이 있다.

• 한국재료학회지
• /
• 제30권10호
• /
• pp.550-557
• /
• 2020

Used in the ceramic tile market as a representative building material, relief ceramic tile is showing increased demand recently. Since ceramic tiles are manufactured through a sintering process at over 1,000 ℃ after uniaxial compression molding by loading granule powders into a mold, it is very important to secure the flowability of granular powders in a mold having a relief pattern. In this study, kaolin, silica, and feldspar are used as starting materials to prepare granule powders by a spray dryer process; the surface of the granule powders is subject to hydrophobic treatment with various concentrations of stearic acid. The effect on the flowability of the granular powder according to the change of stearic acid concentration is confirmed by measuring the angle of repose, tap density, and compressibility, and the occurrence of cracks in the green body produced in the mold with the relief pattern is observed. Then, the green body is sintered by a fast firing process, and the water absorption, flexural strength, and durability are evaluated. The surface treatment of the granule powders with stearic acid improves the flowability of the granule powders, leading to a dense microstructure of the sintered body. Finally, the hydrophobic treatment of the granule powders makes it possible to manufacture relief ceramic tiles having a flexural strength of 292 N/cm, a water absorption of 0.91 %, and excellent mechanical durability.

• 한국조리학회지
• /
• 제13권2호
• /
• pp.1-11
• /
• 2007

The process of Cheonggukjang powderization and application to the western food recipes were established. Cheonggukjang was made and processed into the powder. The optimum condition of Cheonggukjang solution for the powdering process was 50%(w/w). And it was completely grinded by a mixer. Drying condition of a spray dryer was to be injected 1 mL/sec. in $105^{\circ}C$ with 3,000 rpm. The components of Cheonggukjang were 49.7 g/100 g of moisture, 2.6 g/100 g of crude ash, 16.2 g/100 g of crude carbohydrate, 23.4 g/100 g of crude protein, 8.1 g/100 g of crude fat, and 9.3 g/100 g of cellulose. The major amino acid was glutamic acid and its quantity was 4,345.5 mg/100 g. And the next were aspartic acid (2,539.2 mg/100 g) and leucin (1,963.2 mg/100 g). In application, 4 kinds of soup recipes using Cheonggukjang powder were developed. The sensory test showed the acceptability between the soup with the powder and the soup without the powder was significant at odor(p<0.05) in vegetable cream soup and broccoli soup, and at taste(p<0.01) in vegetable cream soup. And the soup with non powder showed more acceptability.

• Journal of Pharmaceutical Investigation
• /
• 제38권2호
• /
• pp.119-126
• /
• 2008

Solid dispersions of poorly water-soluble drug, sibutramine, were prepared with hydrophilic polymer, poly-N-vinylpyrrolidone (PVP), hydroxypropylmethylcellulose (HPMC) and organic acid, citric acid, to improve the solubility of drug. Physicochemical variation and shape of microsphere were characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and Fourier-transform infrared spectroscopy (FT-IR). Microspheres containing additives showed more spherical shape than non additive microspheres. In vitro release behavior of microspheres presented at simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 6.8). The solid dispersion form transformed the drug into an amorphous state and dramatically improved its dissolution rate. These data suggest that the solid dispersion technique is an effective approach for developing the appetite depressant drug products and various pharmaceutical excipients are able to control the release behaviors.

• 한국재료학회지
• /
• 제31권9호
• /
• pp.532-538
• /
• 2021

In this study, a spray dryer is used to make granules of Y₂O₃ and YF₃, and then Y₅O₄F₇ is synthesized following heat treatment of them under Ar gas atmosphere at 600 ℃. Single and binary monomer mixtures are compared and analyzed to optimize photocurable monomer system for DLP 3D printing. The mixture of HEA and TMPTA at 8:2 ratio exhibits the highest photocuring properties and low viscosity with shear thinning behavior. The optimized photocurable monomer and synthesized Y₅O₄F₇ are therefore mixed and applied to printing process at variable solid contents (60, 70, 80, & 85 wt.%) and light exposure times. Under optimal light exposure conditions (initial exposure time: 1.2 s, basic exposure time: 5 s), YOF composites at 60, 70 & 80 wt.% solid contents are successfully printed. As a result of measuring the size of the printed samples compared to the dimensions of the designed bar type specimen, the deviation is found to increase as the YOF solid content increases. This shows that it is necessary to maximize the photocuring activity of the monomer system and to optimize the exposure time when printing using a high-solids ceramic slurry.

• Journal of Microbiology and Biotechnology
• /
• 제29권12호
• /
• pp.1982-1992
• /
• 2019

The alkaliphilic, calcium carbonate precipitating Bacillus sp. strain AK13 can be utilized in concrete for self-repairing. A statistical experimental design was used to develop an economical medium for its mass cultivation and sporulation. Two types of screening experiment were first conducted to identify substrates that promote the growth of the AK13 strain: the first followed a one-factor-at-a-time factorial design and the second a two-level full factorial design. Based on these screening experiments, barley malt powder and mixed grain powder were identified as the substrates that most effectively promoted the growth of the AK13 strain from a range of 21 agricultural products and by-products. A quadratic statistical model was then constructed using a central composite design and the concentration of the two substrates was optimized. The estimated growth and sporulation of Bacillus sp. strain AK13 in the proposed medium were 3.08 ± 0.38 × 10⁸ and 1.25 ± 0.12 × 10⁸ CFU/ml, respectively, which meant that the proposed low-cost medium was approximately 45 times more effective than the commercial medium in terms of the number of cultivatable bacteria per unit price. The spores were then powdered via a spray-drying process to produce a spore powder with a spore count of 2.0 ± 0.7 × 10⁹ CFU/g. The AK13 spore powder was mixed with cement paste, yeast extract, calcium lactate, and water. The yeast extract and calcium lactate generated the highest CFU/ml for AK13 at a 0.4:0.4 ratio compared to 0.4:0.25 (the original ratio of the B4 medium) and 0.4:0.8. Twenty-eight days after the spores were mixed into the mortar, the number of vegetative cells and spores of the AK13 strain had reached 10⁶ CFU/g within the mortar. Cracks in the mortar under 0.29 mm were healed in 14 days. Calcium carbonate precipitation was observed on the crack surface. The mortar containing the spore powder was thus concluded to be effective in terms of healing micro-cracks.