• 한국분말재료학회지
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• 제21권4호
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• pp.251-255
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• 2014

In this study, we optimized dissolution the dissolution conditions of porous amorphous powder to have high specific surface area. Porous metallic glass(MG) granules were fabricated by selective phase dissolution, in which brass is removed from a composite powder consisting of MG and 40 vol.% brass. Dissolution was achieved through various concentrations of $H_2SO_4$ and $HNO_3$, with $HNO_3$ proving to have the faster reaction kinetics. Porous powders were analyzed by differential scanning calorimetry to observe crystallization behavior. The Microstructure of milled powder and dissolved powder was analyzed by scanning electron microscope. To check for residual in the dissolved powder after dissolution, energy dispersive X-ray spectroscory and elemental mapping was conducted. It was confirmed that the MG/brass composite powder dissolved in 10% $HNO_3$ produced a porous MG granule with a relatively high specific surface area of $19.60m^2/g$. This proved to be the optimum dissolution condition in which both a porous internal granule structure and amorphous phase were maintained. Consequently, porous MG granules were effectively fabricated and applications of such structures can be expanded.

• Journal of Pharmaceutical Investigation
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• 제37권4호
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• pp.229-235
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• 2007

Multi-layered granules were prepared by a fluidized-bed coater and uniformed granules were obtained with a size range between $950{\sim}1000{\mu}m$ in diameter. The granule system was composed of three layers, i.e. seed layer with sugar sphere bead and a water-swellable polymer, middle layer with a drug, solubilizer and polymer, and the top layer of porous membrane with a polymeric binder. The aim of this work is to find out the dependence of a drug dissolution rate on the amount of a water-soluble binder and a solubilizer in the granule system. The results showed that the higher amount of hydrophilic binder in the porous membrane, gave the bigger pore size and porosity and made faster dissolution rate and also the higher amount of solubilizer in drug layer enhanced the dissolution rate of drug.

• 공업화학
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• 제22권6호
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• pp.642-647
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• 2011

회전형 휘발성 산화장치(voloxidizer)와 200 g $U_3O_8$ 분말을 사용하여 초기 미세 입자층의 운동형태, 열처리 온도 및 시간, voloxidizer의 회전속도에 따른 다공성 그래뉼의 회수율과 특성을 분석하였다. 초기 미세 입자층의 운동형태에 따른 1 mm 이상의 그래뉼의 회수율은 rolling 운동 때보다 slumping 운동일 경우에 보다 높았다. 초기 미세 입자층이 rolling 운동형태인 경우에는 미세입자로부터 그래뉼이 생성됨에 따라서 slumping 운동형태로 변하며 slumping 빈도가 매우 높았다. 열처리 온도의 증가 및 10 h까지는 시간의 증가에 따라서 그래뉼의 회수율이 매우 크게 증가하였다. Slumping 운동형태를 보이는 초기 미세 입자층의 경우에 voloxidizer의 회전속도가 증가함에 따라서 그래뉼의 회수율 은 81.5에서 88.7%로 증가하였으나, 그래뉼 특성 측면에서 보면 회전속도가 2 rpm인 경우에 밀도, 파쇄강도, 구형도가 가장 높았다.

• 한국세라믹학회지
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• 제54권2호
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• pp.108-113
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• 2017

The use of aluminum-based coagulants in water pretreatment is being carefully considered because aluminum exposure is a risk factor for the onset of Alzheimer's disease. Lightly burned-dolomite kiln dust (LB-DKD) was evaluated as an alternative coagulant because it contains high levels of the healthful minerals calcium and magnesium. An organic pore forming agent (OPFA) was incorporated to prepare porous granules after OPFA removal through a thermal decomposition process. A spray drying method was used to produce uniform and reproducible spherical granules with low density, since fine dolomite particles have irregular agglomeration behavior in the hydration reaction. The use of fine dolomite powder and different porosity granules led to a visible color change in raw algae (RA) containing water, from dark green to transparent colorlessness. Also, dolomite powders and granules exhibited a mean removal efficiency of 48.3% in total nitrogen (T-N), a gradual increase in the removal efficiency of total phosphorus (T-P) as granule porosity increased. We demonstrate that porous dolomite granules can improve the settling time and water quality in summer seasons for the emergent treatment of excessive algal blooms in eutrophic water.

• Journal of Periodontal and Implant Science
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• 제24권1호
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• pp.185-195
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• 1994

This study was conducted to evaluate the healing potential of hydroxyapatite and demineralized freeze dried bone in 5 dogs. Chronic periodontitis was induced by ligating elastic wire randomized as follows. The group in which only flap operation was performed was used as control. The group in which flap operation using nonresorbable nonporous hydroxyapatite (Orthomatrix)was performed was used as experimental I. The group which flap operation using resorbable porous hydroxyapatite (Biocoral) was performed as experimental II. The group in which flap operation using demineralized freeze-dried bone was performed was used as experimental III. Thereafter dogs serially sacrificed at the 1,2,4 and 8 weeks and the specimens were prepared, and stained with Hematoxilin-Eosin stain for the light microscopic evaluation. The results of the this study were as follows : 1. Control group : progressive inflammatory cell infiltration till 4 weeks and epithelial undergrowth. 2. Group I. : epithelial undergrowth and new bone formed with fibrous margin around HA granule. 3. Group II. : no epithelial undergrowth and direct bone formation at the porous granule 4. Group III. : could not see epithelial undergrowth but obviously new cementum formation.

• 한국재료학회지
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• 제22권6호
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• pp.309-315
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• 2012

Metal foam has many excellent properties, such as light weight, incombustibility, good thermal insulation, sound absorption, energy absorption, and environmental friendliness. It has two types of macrostructure, a closed-cell foam with sealed pores and an open-cell foam with open pores. The open-cell foam has a complex macrostructure consisting of an interconnected network. It can be exploited as a degradable biomaterial and a heat exchanger material. In this paper, open cell Mg alloy foams have been produced by infiltrating molten Mg alloy into porous pre-forms, where granules facilitate porous material. The granules have suitable strength and excellent thermal stability. They are also inexpensive and easily move out from open-cell foamed Mg-Al alloy materials. When the melt casting process used an inert gas, the molten magnesium igniting is resolved easily. The effects of the preheating temperature of the filler particle mould, negative pressure, and granule size on the fluidity of the open cell Mg alloy foam were investigated. With the increased infiltration pressure, preheat temperature and granule sizes during casting process, the molten AZ31 alloy was high fluidity. The optimum casting temperature, preheating temperature of the filler particle mould, and negative pressure were $750^{\circ}C$, $400-500^{\circ}C$, and 5000-6000 Pa, respectively, At these conditions the AZ31 alloy had good fluidity and castability with the longest infiltration length, fewer defects, and a uniform pore structure.

• 한국추진공학회지
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• 제15권6호
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• pp.7-14
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• 2011

하이드라진을 단일추진제로 사용하는 추력기는 인공위성 및 발사체의 자세제어를 위한 용도로 다양한 크기로 제작되어 사용되어왔다. 하이드라진과 분해생성물인 암모니아의 독성으로 인해 취급과 시험이 매우 까다롭기 때문에 여러 설계 변수로 인한 영향을 수치해석을 이용하여 분석 한다면 시간과 비용을 절약할 수 있다. 본 연구에서는 촉매대를 1차원 다공성 매질로 모델링하여 수치해석을 수행하였다. 이를 통하여 촉매대 파손에 따른 특성변화를 고려하여 발생 가능한 물리현상을 수치해석을 통해 파악하였다.

• 한국환경농학회지
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• 제11권2호
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• pp.155-162
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• 1992

수용해도가 2.53ppm인 KC-6620을 수중용출기간이 20일 정도인 입제로 제제하기 위하여 원제에 대한 용출지연효과가 가장 큰 다공성 증량제를 선발하고, PEG를 부제로 첨가한 흡착식 입제를 제제하여 실내에서 수중용출속도를 측정하였다. 1. 다공성 증량제중 KC-6620에 대하여 용출지연효과를 나타낸 것은 bentonite 소결공립이었으나 수중에 침적 20일후의 용출율이 매우 낮았다. 2. Bentonite에 pyrophyllite를 혼합하고 조립한 다음 소결시킴으로써 흡유가가 증가하였으며, 이 공립으로 제제한 KC-6620 입제의 수중용출속도도 증가하였다 BP60 입제의 경우 침적 20일후에 85% 이상의 용출율을 보여 시험한 입제중 단기용출지연제제로 가장 적합하였다. 3. BP입제는 PEG를 부제로 첨가하여 용출속도를 증가시킬 수 있었으며, PEG의 첨가비가 공립의 흡유가까지 증가할수록 용출속도도 증가하였다. 4. BP40 입제는 입제중의 유효성분함량이 높을수록 수중용출속도가 느려져서 제제농도가 용출속도를 좌우하는 가장 큰 요인이었다.

• 한국재료학회지
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• 제20권3호
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• pp.155-160
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• 2010

In this study, we investigated primary biocompatibility and osteogenic gene expression of porous granular BCP bone substitutes with or without strontium (Sr) doping. In vitro biocompatibility was investigated on fibroblasts like L929 cells and osteoblasts like MG-63 cells using a cell viability assay (MTT) and one cell morphological observation by SEM, respectively. MTT results showed a cell viability percent of L929 fibroblasts, which was higher in Sr-BCP granules (98-101%) than in the non-doped granules (92-96%, p < 0.05). Osteoblasts like MG-63 cells were also found to proliferate better on Sr-doped BCP granules (01-111%) than on the non-doped ones (92-99%, p < 0.05) using an MTT assay. As compared with pure BCP granules, SEM images of MG-63 cells grown on sample surfaces confirmed that cellular spreading, adhesion and proliferation were facilitated by Sr doping on BCP. Active filopodial growth of MG-63 cells was also observed on Sr-doped BCP granules. The cells on Sr-doped BCP granules were well attached and spread out. Gene expression of osteonectin, osteopontin and osteoprotegrin were also evaluated using reverse transcriptase polymerase chain reaction (RT-PCR), which showed that the mRNA phenotypes of these genes were well maintained and expressed in Sr-doped BCP granules. These results suggest that Sr doping in a porous BCP granule can potentially enhance the biocompatibility and bone ingrowth capability of BCP biomaterials.

• 한국농공학회논문집
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• 제48권6호
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• pp.113-124
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• 2006

The feasibility of the up- and down-flow constructed wetland was examined fur rural wastewater treatment in Korea. Many constructed wetland process was suffered from substrate clogging and high plant stresses because of long term operation. The up- and down-flow constructed wetland process used porous granule materials (charcoal pumice : SSR=10:20:70) for promoting intake rate of nutrient to plant, and especially flow type was designed continuously repeating from up-flow to down-flow. $BOD_5$ and SS was removed effectively by the process with the average removal rate being about 75% respectively. The wetland process was effective in treating nutrient as well as organic pollutant. Removal of TN and TP were more effective than other wetland system and mean effluent concentrations were approximately 7.5 and $0.4mg\;L^{-1}$ which satisfied the water quality standard for WWTPs. The treatment system did not experience any clogging or accumulations of pollutants and reduction of treatment efficiency during winter period because constructed polycarbonate glass structure prevented temperature drop. Considering stable performance and effective removal of pollutant in wastewater, low maintenance, and cost-effectiveness, the up- and down-flow constructed wetland was thought to be an effective and feasible alternative in rural area.