• 한국약용작물학회지
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• 제21권5호
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• pp.401-414
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• 2013

Ginsenoside Rg3 (G-Rg3) contained only in red ginseng has been found to show various pharmacological effects such as an anticancer, antiangiogenetic, antimetastastic, liver protective, neuroprotective immunomodulating, vasorelaxative, antidiabetic, insulin secretion promoting and antioxidant activities. It is well known that G-Rg3 could be divided into 20(R)-Rg3 and 20(S)-Rg3 according to the hydroxyl group attached to C-20 of aglycone, whose structural characteristics show different pharmacological activities. It has been reported that G-Rg3 is metabolized to G-Rh2 and protopanaxadiol by the conditions of the gastric acid or intestinal bacteria, thereby these metabolites could be absorbed, suggesting its absolute bioavailability (2.63%) to be very low. Therefore, we reviewed the chemical, physical and biological transformation methods for the production on a large scale of G-Rg3 with various pharmacological effects. We also examined the influence of acid and heat treatment-induced potentials on for the preparation method of higher G-Rg3 content in ginseng and ginseng products. Futhermore, the microbial and enzymatic bio-conversion technologies could be more efficient in terms of high selectivity, efficiency and productivity. The present review discusses the available technologies for G-Rg3 production on a large scale using chemical and biological transformation.

• 환경생물
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• 제23권4호
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• pp.383-389
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• 2005

The effect of different mulching materials on mungbean production was studied. The general objective was to assess the ecological effects of mulching materials in sustainable mungbean production. Specifically, the study aimed to determine the effects of different mulching materials on the chemical, physical and biological soil properties, on weed control and yield, and to identify mulching materials that are environmentally friendly in mungbean production. The experiment was conducted at the Fruit and Vegetables Seeds Center, Science City of $Mu/tilde{n}oz$, Nueva Ecija, Philippines from May to July 2004. The initial soil chemical properties were: pH of 6.4, 2.0 percent organic matter content, 0.10 percent total nitrogen, 22 ppm phosphorus, and 370 ppm available potassium. The soil microbial loads were $8\times10^4\;CFU\;g^{-1}$ for bacteria and $14\times10^4\;CFU\;g^{-1}$ for fungi. Mushroom spent mulch increased soil organic matter with an average of 3.13 percent, nitrogen with an average of 0.16 percent and the highest number of bacterial count with $3.4\times10^8\;CFU\;g^{-1}$. Use of mulch, except rice straw mulch, generally increased mungbean yield. The best mulching material for high yield production of mungbean was black polyethylene plastic film, although environmentally unfriendly.

• 생물환경조절학회지
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• 제2권2호
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• pp.110-118
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• 1993

본 실험은 유기물 대체재료로서 peatmoss(원예용 배양토)의 물리, 화학적 특성을 조사하고, 배양상 종류와 관수방법이 고추묘의 생육에 미치는 영향을 보고자 실시하였으며 그 결과는 다음과 같다. 1. Peatmoss에 밭흙을 1:1, 1:2로 배합한 경우에도 고추묘의 생육에 적합한 화학적 성질을 보였다. 2. 고추묘의 발아율은 저면관수보다 철수관수 처리시 월등히 높았으며, peatmoss, TKS 단독 처리구를 제외하고는 배양토 종류간의 차이는 없었다. 3. 전반적으로 철수관수보다 저면관수 처리시 생육이 양호하였으며, 특히 peatmoss와 밭흙을 1:1, 1:2로 배합한 처리구의 생육이 가장 양호하였다.

• Elastomers and Composites
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• 제54권2호
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• pp.142-148
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• 2019

In this study, the effects of filler particle size and shape on the physical properties of silicone rubber composites were investigated using inorganic fillers (Minusil 5, Celite 219, and Nyad 400) except silica, which was already present as a reinforcing filler of silicone rubber. Fillers with small particle sizes are known to facilitate the formation of the bound rubber by increasing the contact area with the polymer. However, in this experiment, the bound rubber content of Celite 219-added silicone composite was higher than that of Minusil 5-added silicone composite. This was attributed to the porous structure of Celite 219, which led to an increase in the internal surface area of the filler. When the inorganic fillers were added, both thermal decomposition temperature and thermal stability were improved. The bound rubber formed between the silicone rubber and inorganic filler affected the degree of crosslinking of the silicone composite. It is well-known that as the size of the reinforcing filler decreases, the reinforcing effect increases. However, in this experiment, the hardness of the composite material filled with Celite 219 was the highest compared to the other three composites. Furthermore, the highest value of 2.19 MPa was observed for 100% modulus, and the fracture elongation was the lowest at 469%. This was a result of excellent interaction between Celite 219 filler and silicone rubber.

• 보존과학회지
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• 제4권1호
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• pp.59-66
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• 1995

The living body consists of proteins, carbohydrates and fats. The above components are unstable to the change of circumstances ; thus ; when they are buried under the ground for a long time, they are disintegrated by physical effects such as pressure, water etc. However, it was recently reported that the part of the components of living body, especially fat thought in small guantity, remained in a relative stable state for many milleniuns. In addition, turned out that the structure of the composition of the fatty acid and sterol is different according to their species. For example, the plants - rice, barley, bean - and the animals - (togs, cow, pig, fish - have different structure of fat. Residual fat analysis is a research in the chemical composition of fat vemained in archaeological evidences on the basis of chemical structural differences as mentioned here in above. This paper introduces the residual fat analysis of archaeological evidences practical in Japan.

• KSBB Journal
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• 제6권2호
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• pp.157-166
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• 1991

The structural properties of cellulose are significantly changed with the progress of hydrolysis reaction. The effects of changes on such properties of cellulosic substrate as crystallinity, amicessibility of enzyme to the active site of cellulose surface, and particle size on the kinetics of enzymatic hydrolysis have been studied. Among those physical studies, the apparent surface active site of cellulose particle was found to have the most significant effect on the hydrolysis kinetics. Based on the experimental results, the adsorption affinity of enzyme and hydrolysis rate were mainly influenced by the surface roughness of cellulose particle. The extent of accesssible active site may be expressed as the change of particle diameter. The Langmuir isotherm was proposed in terms of enzyme activity to explain the actual action of enzyme protein.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.132-135
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• 2005

하이드라진을 추진제로 쓰는 아크젯 추력기 내의 열화학적 유동장을 전산유체를 이용해 해석하였다. Ohm가열 및 Lorentz힘을 고려하기 위하여 Maxwell 방정식과 연계된 RANS 방정식을 이용하였으며, 매우 빠른 반응 및 광학적으로 두꺼운 매질을 가정하여 이온화와 열복사를 해석에 포함하였다. 해석의 결과는 아크젯 추력기 내부 유동의 열-물리적 이해와 더불어 0.6 kW 가열에 의하여 하였을 때 추력과 비추력이 각각 20%와 70%가 향상됨을 보여주었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.41-45
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• 1999

Microbial cellulose has many potential applications due to its excellent physical properties. The production of cellulose from Acetobacter xylinum in submerged culture is, however, beset with numerous problems. The most difficult one has been the appearance of negative mutants under shaking culture conditions, which is deficient of cellulose producing ability. Thus genetic instability of Acetobacter xylinum under shaking culture condition made developing a stable mutant major research interest in recent years. To find a proper type of bioreactor for the production of microbial cellulose, several production systems were developed. Using a reactor system with planar type impeller with bottoms sparging system, it was possible to produce 5 g/L microbial cellulose without generating cellulose minus mutants, which is comparable to that of static culture system.

• Carbon letters
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• 제12권2호
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• pp.95-101
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• 2011

To investigate new applications for illite as an additive for carbon-based composites, the composites were prepared with and without illite at different heat-treatment temperatures. The effects of the heat-treatment temperature on the chemical structure, microstructure, and thermal oxidation properties of the resulting composites were studied. As the heat-treatment temperature was increased, silicon carbide SiC formation via carbothermal reduction increased until all the added illite was consumed in the case of the samples heat-treated at $2,300^{\circ}C$. This is attributed to the intimate contact between the $SiO_2$ in the illite and the phenol carbon precursor or the carbon fibers of the preform. Among composites prepared at all temperatures, those with illite addition exhibited fewer pores, voids, and interfacial cracks, resulting in larger bulk densities and lower porosities. A delay of oxidation was not observed in the illite-containing composites prepared at $2,300^{\circ}C$, suggesting that the illite itself absorbed energy for exfoliation or other physical changes. Therefore, if the illite-containing C/C composites can reach a density generally comparable to that of other C/C composites, illite may find application as a filler for C/C composites. However, in this study, the illite-containing C/C composites exhibited low density, even when prepared at a high heat-treatment temperature of $2300^{\circ}C$, although the thermal oxidation of the resulting composites was improved.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2003년도 춘계학술대회
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• pp.150-151
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• 2003

Benzoyl peroxide is a high production volume chemical, which was produced about 1,375 tons/year in Korea as of 2001 survey. Most of them are used as initiators in polymerization, catalysts in the plastics industry, bleaching agents for flour and medication for acne vulgaris. The substance is one of the sever chemicals of which human and environmental risks are being assessed by National Institute of Environmental Research under the frame of OECD SIDS Program. It has a melting point of 104-106 $^{\circ}C$ and has solubility of 9.1 mg/1 in water at 25 $^{\circ}C$. The substance was readily biodegradable (83 % after 21days) and had toxic effects to aquatic organisms. The range of 72 hr-EbC50 (biomass) for algae was 0.07-0.44 mg/1 and 48 hr-EC50 for daphnia was 0.07-2.91 mg/1. The LC50 of acute toxicity to fish was 0.24-2.0 mg/1. Although the toxic effects of benzoyl peroxide to aquatic organisms were investigated, environmental monitoring data were not studied. In this study, distribution of the chemical among multimedia environment was estimated using EQC model based on the physical-chemical properties to evaluate the risk of benzoyl peroxide in environment. In level I, II calculation the chemical was distributed to soil (68.3 %) and water (28.7 %). In level III calculation it was primarily distributed to soil (99.9 %) and overall residence time of 3.4 years was estimated. Benzoyl peroxide could be persistent in environment.