• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.200-207
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• 2007

Single base propellant using a nitrate ester compound NC decomposes naturally during storage time. Therefore, the research for storage life extension is necessary to single base propellant. In this research, $CaCO_3$ inorganic stabilizer had been added into single base propellants up to 0.3%, and the accelerated aging test of the propellant was started. And then, with applying the Arrhenius equation, the storage life of the test of the propellant was contrasted with that of reference propellant. As a result, the storage life of the propellant containing $CaCO_3$ inorganic stabilizer was about twice longer than the reference propellant.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.187-193
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• 1994

무전해 동도금액에서의 각종 안정제, 촉진제등의 첨가제에 따른 영향을 고찰하였다. 욕의 기본성분은 황산구리 10g/1, EDTA-2Na 40g/1, 포르말린 3ml/1, pH조절용 수산화나트륨 용액으로 조성하였고, 안정제, 도금촉진제 및 계면활성제의 첨가에 따른 분극곡선을 검토하여 도금욕의 경향을 검토한뒤 농도변화에 따른 도금속도를 측정하여 최적조건을 구하였다. 안정제는 $\alpha$, $\alpha$'-dipyridy1과 NaSCN을 혼합 사용하는 것이 좋았으며 촉진제로는 pyridine이 계면활성제로는 PEG 4000이 좋았다. 첨가량은 5mg/1이하의 미량이었으며 이후 첨가량이 증가함에 따라 증가함에 따라 도금속도는 직선적으로 감소하였다.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.287-293
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• 2005

In this work, to develop soil inoculant which maintains stable viable cells and normalized quality, studies on micro-encapsulation with bacteria and yeast cells were performed by investigating materials and methods for micro-encapsulation as well as variation and stability of encapsulated cells. Preparation of capsule was conducted by application of extrusion system using micro-nozzle and peristaltic pump. K-carragenan and Na-alginate were selected as best carrier for gelation among K-carageenan, Na-alginate, locust bean gum, cellulose acetate phthalate (CAP), chitosan and gelatin tested. Comparing the gels prepared with Bacillus sp. KSIA-9 and carriers of 1.5% concentration, although viable cell of K-carragenan and Na-alginate was six times higher than those of other, Na-alginate was finally selected as carrier for gelation because it is seven times cheaper than K-carragenan. The gel of 1.5% Na-alginate was also observed to have the best morphology with circular hardness polymatrix and highest viable cell. When investigating the stability of encapsulated cells and the stabilizer effect, free cells were almost dead within 30 or 40 days whereas encapsulated cells decreased in 10% after 30 days and 15-30% even after 120 days. As stabilizer for maintaining viable cell, both 1% starch and zeolite appeared to possess the level of 70-80% cell for bacteria and yeast until after 120 days.

• Journal of Adhesion and Interface
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• v.20 no.4
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• pp.146-154
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• 2019

In this study, alkoxysilane-functionalized amphiphilic polymer (AFAP), which have hydrophilic segment and hydrophobic segment functionalized by alkoxysilane group at the same backbone, was synthesized and used as a dispersant and control agent for reaction rate in the preparation of colloidally stable organic-inorganic (O-I) hybrid sols. After reaction with fluorosilane compounds, fluorinated O-I hybrid sols were prepared and coated onto glass substrate to form hydrophobic O-I hybrid coating films through low-temperature curing process. Surface hardness and hydrophobicity of cured coating films were varied with type of solvent and composition of AFAP and fluorinated alkoxysilane compounds. At appropriate solvent and composition of fluorinated alkoxysilane compounds, O-I hybrid coating film having high transparency and surface hardness could be prepared, which could be applicable to cover window of solar cell and displays.

• Microbiology and Biotechnology Letters
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• v.15 no.6
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• pp.381-387
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• 1987

Distribution of superoxide dismutase (SOD) which catalyzes the dismutation of superoxide radicals to hydrogen peroxide and oxygen has been examined in various genera of bacteria. SOD was produced by various bacteria independent of genus and species with variation in superoxide dismutase activity of each bacteria. Bacillus circulans which produced relatively large amount of SOD was selected and used to investigate the optimum culture conditions and further studies. The compositions of optimum culture medium for the enzyme production were 1% glucose, 2% polypeptone, 0.l% NaCl, and 0.2mM of methyl viologen and initial pH was 6.0. The highest enzyme production was observed after 20 hours of cultivation at 3$0^{\circ}C$ on a reciprocal shaker. The enzyme activity was maintained stably for a relatively long period by the addition of 5% ethanol in pH 5.0, 0.01M acetate buffer.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.513-520
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• 2017

The application possibility of an alternative new method with low energy consumption was studied for the eco-friendly fabrication of foamed glasses from waste glasses. As a result, fabricating temperature can be reduced under $300^{\circ}C$ without using various expensive inorganic oxidants. The foamed glass can be fabricated at a proper mixing ratio of the waste glass powder, water glass, little surfactant and bubble stabilizer by induction heating method. In the experimental range, the assured optimal condition is 4 min heating on the induction machine with a steel-container ($100mm{\times}100mm{\times}20mm$) and followed by evaporating and drying process for 11 min with 110 g of glass powder, 80 g of water glass, 3 g of surfactant and 0.2 g of bubble stabilizer. When the foamed glass was fabricated at the optimal condition, the density of the glass was $0.85g/cm^3$ and the heat conduction was $0.052W/h{\cdot}K$. In addition, the compressive strength of the glass was above $50kg/cm^2$.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.30-36
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• 2013

This paper presents a method to estimate a storage life for loss of stabilizer content as storage periods using accelerated life test data. The estimate of storage life based on deterministic accelerated life test and degradation data cannot describe a condition distribution and storage life distribution. Previously, the method to show the condition distribution and storage life distribution by using gamma process has been studied. But it has limitation because it is impossible to collect the deterioration data at initial production phase. The estimated storage life presented by this study shows the similar value to previous studies and the method can describe the condition distribution and storage life distribution. So, the estimation method studied in this paper can be used for a life cycle management about deterioration of propellant for propulsion unit or components of missile, too.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.366-372
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• 1993

This study mainly designed to high quality of mirin production by using protopast fusion. In order to enhance the acid carboxypeptidase (ACPase) activity by the method of protoplast fusion. In order to enhance the acid carboxypeptidase (ACPase) activity by the method of protopalst fusion, the mutants, Aspergillus oryzae 9-12 and Aspergillus shirosamii IFO 6082-60 were selected by mutation among various mutants. Protoplast of Aspergillus oryzae 9-12 and Aspergillus shirousamii IFO 6082-60 were formed effectively by incubation of the mixtures of chitinase (10mg/ml), cellulase (10mg/ml) and zymolase 20T (5mg/ml). For protopalst fusion, the mixture of two mutant were fused to effective under the optimum conditions by solutions containing 30% PEG 6,000, 0.01M $CaCl_2\;2H_2O$, 0.6M KCl and 0.05M glycine. Fusion frequency was 0.71% and fusant, F-50 appeared ACPase activity of 20,800 unit/g which has 1.5 times higher than that of each mutants.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.138-144
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• 1997

A new biopolymer YU-122 from Metarrhizium anisopliae (Metschn.) Sorok consisting of glucose and galactose was tested for its physical properties and flow behavior characteristics. Xanthan gum showed slightly higher viscosity than biopolymer YU-122. Viscosity of biopolymer YU-122 at various pHs and temperatures was also tested. The viscosity of biopolymer YU-122 was very stable up to pH 11 and $60^{\circ}C$, indicating that it has a great possibility for the application such as food additives, emulsifier, and drug release agents. Flow behavior index (n) from Power Law equation is 0.173. Biopolymer YU-122 solution was a pseudoplastic non-Newtonian fluid, which indicated that it had one or more side chains. When biopolymer YU-122 was used as a emulsifier, it stabilized the emulsion up to 120 hours, which was much better than xanthan gum. The biopolymer YU-122 could form an excellent but less clear film compared with xanthan and pullulan.

• Analytical Science and Technology
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• v.28 no.1
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• pp.33-39
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• 2015

CdS-QD particles are a nano-sized semiconducting crystal that emits light. Their optical properties show great potential in many areas of applications such as disease-diagnostic reagents, optical technologies, media industries and solar cells. The wavelength of emitting light depends on the particle size and thus the quality control of CdS-QD particle requires accurate determination of the size distribution. In this study, CdS-QD particles were synthesized by a simple ${\gamma}$-ray irradiation method. As a particle stabilizer polyvinyl pyrrolidone (PVP) were added. In order to determine the size and size distribution of the CdS-QD particles, sedimentation field-flow fractionation (SdFFF) was employed. Effects of carious parameters including the the flow rate, external field strength, and field programming conditions were investigated to optimize SdFFF for analysis of CdS-QD particles. The Transmission electron microscopy (TEM) analysis show the primary single particle size was ~4 nm, TEM images indicate that the primarty particles were aggregated to form secondary particles having the mean size of about 159 nm. As the concentration of the stabilizer increases, the particle size tends to decrease. Mean size determined by SdFFF, TEM, and dynamic light scattering (DLS) were 126, 159, and 152 nm, respectively. Results showed SdFFF may become a useful tool for determination of the size and its distribution of various types of inorganic particles.