• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.701-709
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• 1992

Silver particles were impregnated on carbon black with colloidal method and used as catalyst for oxygen electrode in alkaline fuel cell. With the addition of sodium dodecylbenzenesulfonate in $AgNO_3$ and $NaBH_4$solution, colloidal solution was made and confirmed with electrophoresis test. Effects of particle size on electrode performance were studied and $200{\AA}$ of silver particle size shown the highest value of mass activity. The aggromeration of silver particle was Influenced with surfactant amount, stirring time and heat treatment. Considering the increase of particle size caused of operating temperature, recommendable particle size of silver catalyst for manufacturing the electrode was $100{\AA}$. Dispersity of carbon black was investigated and reagglomeration was appeared after homogenizing 30 sec.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.299-306
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• 2016

In this study, new hydroxyapatite powder surface composites were investigated for protective effects against ultraviolet rays. Hydroxyapatite (HAp) is biocompatible and does not cause nebula phenomenon on skin. We investigated the surface modification of hydroxyapatite to improve UV block and skin usage. Dimethicone, lauroyl lysine, triethoxycaprylylsilane and silica were used as coating agents for the surface modification of HAp. To prepare the composite complex of the modified surface, the dimethicone, lauroyl lysine and triethoxycaprylylsilane were prepared by a dry process, and silica by a hydrothermal synthesis method. The HAp-silica was chosen as the best composite powder when measuring its sun protection levels. We investigated the characteristics of the surface of HAp-silica by SEM, particle size analyzer and energy dispersive spectrometry (EDS). Additionally, the stability in the formulation, UV block effect, and safety in BB creams were investigated. In conclusion, HAp-silica prepared by the modification of HAp complex surface improved the skin usage and UV block effect by enhancing the white cloudy phenomenon. These results indicate that HAp-silica may be used for UV block cosmetics.

• Geotechnical Engineering
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• v.13 no.2
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• pp.9-16
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• 1997

Cut-off methods of controlling leachate migration from waste landfills and contaminated sites are studied. Permeability and chemical compatibility tests are prrforlned on slurry wall materials including soil-bentonite, cement-bentonite, cement / fly ash-bentonite, plastic concrete. Hydraulic conductivity of soil-bentonite mixture is the lowest of these four bacuill materials. The leachate from municipal solid waste has little influence on the permeability of the backfill materials. The bentonite slurry becomes flocculated and aggregated when exposed to the leachate. The results of the permeability test showed that the hydraulic conductivities of the backfill materials are in the order soil-beiltonite, Plastic concrete, cement-bentonite. And the result c: the compatibility test showed increase in permeability due to the effects of leachate. Thus, in designing the slurry wall it is essential to check the behaviour of the bentonite slurry and backfill materials on the compatibility with the contaminants.

• Proceedings of the Ginseng society Conference
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• 1984.09a
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• pp.37-43
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• 1984

노화는 모든 다세포 유기물의 특징이다. 노화가 됨에 따라서 효소활성 및 면역반응의 감소와 과산화지질과 지방갈색물질의 축적, 효소와 염색질을 포함하는 단백질 구조의 변화, 호르몬계의 불균형 등이 일어난다. 그렇지만, 노화가 어떻게 일어나는지에 관하여는 현재까지 확실하지 않다. 본 연구진은 노화와 관련된 효소들에 관하여 연구를 하여 왔으며, 노화가 진행되는 동안의 효소의 활성을 유지시켜주거나, 또는 효소의 활성이 감소되는 것을 지연시켜 주는 물질을 찾고자 노력하였다. 그 가운데 하나로서, 고려인삼 추출물을 흰쥐에 기간별로 투여하여 효소활성의 차이, 열에 대한 안정성, 기질에 대한 친화력, 전기 영동 상의 이동성과 면역적인 반응을 대조군과 비교하였다. Glucose-6-phosphate dehydrogenase, 6-phosphog-luconate dehydrogenase, glutathione redutease, glutathion peroxidase와 같은 노화와 관련된 효소들의 활성을 고려인삼 추출물을 1개월간 흰쥐에 ($60{\~}80$g)투여하여 대조군과 비교 조사하였으나, 별 차이가 없었다. 그러나 고려인삼 추출물을 15개월간 투여하였을 때에는 이러한 노화관련 효소들의 활성이 급격히 증가함이 ($70{\~}200\%$) 관찰되었다. 예견된 바와 같이, 효소의 열에 대한 안정성과 기질에 대한 친화력도 증가함이 관찰되었다. 그러나 glucose-6-phosphate dehydrogenase의 경우에서 전기영동상의 차이 및 면역적인 반응은 대조군과 유사하였다. 이상의 결과는 고려인삼 추출물이 노화와 관련된 효소들의 활성이 감소되는 것을 지연시켜줄 수 있으며, 노화를 어느정도 지연시켜 줄 수 있음을 의미한다. 이와 같은 결과를 포함한 실험자료를 국제 인삼심포지움에서 발표할 것이다.$-tocopherol의 항 산화작용을 더욱 효과적으로 촉진 시킬 것으로 생각된다.-L(독성 호르몬-L)의 작용을 억제함으로서 암환자의 체중 감소를 방지하고, 식욕감퇴를 개선할것으로 생각된다.해되었으며, $Rb_{1}$은 장내의 효소와 tetracycline-resistantant bacteria에 의해 Rd와 2 종류의 미확인 물질로 분해되었다.xA_{2}$ synthetase 억제제인 imidazole의 효과와 유사하였다. 4. G-Re는 $1{\times}10^{-5}g/ml$ 이하의 농도에서는 효과가 없으나 $1{\times}10^{-4}g/ml$ 이상의 농도에서 농도의존적으로 유의성 있는 $PGE_{2},\;PGF_{2}{\alpha},\;TXB_{2}$의 생성억제와 함께 6-keto-$PGF_{1}{\alpha}$ 증가를 보였다. 이는 prostacyclin synthetase를 자극하는 serotonin의 효과와 같은 작용으로서 prostacyclin synthetase 억제제인 tranylcypromine에 대하여 길항효과를 보였다. 5. $TxB_{2}$생성억제 작용을 나타내는 ginsenoside들의 효과를 뒷받침하기 위하여 인삼 saponin 성분을 전처치한 patelet rich plasma에서 혈소판 응집시험 결과, ADP로 유도된 혈소판 응집반응에는 모든 인삼 saponin 성분들이 효과가 없었으나 arachidonic acid로 유도된 혈소판 응집반응에는 $G-Rb_{2}$, G-Rc, G-Re의 순으로 농도 의존적인 억제현상을 보였다. 이상의 결과와 같이 인삼 saponin 성분들은 arachidonic acid로부터 cyclooxygenase를

• Composites Research
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• v.23 no.3
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• pp.13-18
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• 2010

One of the biggest challenges in the nano-field is how to effectively disperse nano-scale particles, especially CNTs, which are strongly agglomerated by intermolecular van der Waals forces. This study suggests a new method, discharge flocking, in order to disperse nano-scale particles effectively, which combines corona discharge phenomenon and a traditional electrostatic flocking process. In order to evaluate the discharge flocking process, composite specimens were fabricated by the process and RFI(resin film infusion) process, and then the mechanical and electrical properties of the specimens were measured and compared. Moreover, the evaluation of gas discharge effect on the CNTs and epoxy was performed to compare the mechanical and electrical properties of the composite specimens including the plasma treated CNTs. The experimental results showed that the electrical and mechanical properties of the specimens fabricated by the discharge flocking process were similar to those of the RFI process. In addition, plasma treated CNTs were not affected by gas discharge during the discharge flocking process.

• Korean Journal of Food Science and Technology
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• v.53 no.4
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• pp.365-374
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• 2021

In this study, the effect of enzyme-modified starch used in the preparation of filled hydrogel powder loaded with curcumin (FHP) on redispersibility, thermal and UV stability, and curcumin retention during in vitro digestion was investigated. FHP maintained stability without layer separation when redispersed and showed more stability against UVB than the emulsion powder (EMP). There was no significant difference in the chemical stability of curcumin between rice starch-based filled hydrogel powder (RS-FHP) and enzyme-modified starch-based filled hydrogel powder (GS-FHP). However, the gel matrix of GS-FHP maintained greater stability of lipid droplets in the stomach compared to RS-FHP, thereby improving the retention rate of curcumin after in vitro digestion. GS-FHP could be used as a novel material for developing premixes that require stable formulation and maintenance of functional substances, as it can increase the dispersion stability and retention rate of functional substances after digestion.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.601-609
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• 2018

Microcystis aeruginosa, a freshwater cyanobacteria species known to be one of the most predominant species responsible for cyanobacterial harmful algal blooms (CyanoHABs). It has been frequently associated with the contamination of neurotoxins and peptide hepatotoxins, such as microcystin and lipopolysaccharides-LPSs. CyanoHABs control technologies so far put in place do not provide a fundamental solution and cause secondary pollution linked with the control measures. For this study, algicidal peptides, which have been reported to be non-toxic and to have antimicrobial properties, were employed for the development of novel eco-friendly control against CyanoHABs. The four peptides (CMA1, CMA2, HPA3P, and HPA3NT3) selected in this study showed significant algicidal effects against M. aeruginosa cells inducing cell aggregation and flotation. Moreover, the newly generated peptides (K160242-5) with certain modifications also displayed high algicidal activity. The algicidal activity of the peptides was found to depend on the concentrations and structures of each of amino acid. The results of this study suggested a novel possibility of CyanoHABs control using the non-toxic algicidal peptides.

• The Journal of Society for e-Business Studies
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• v.8 no.2
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• pp.77-98
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• 2003

A web-based information system, that is a dominant type of information systems, suffers from the "web crisis" in development and maintenance of the system. To cope with the problem, a technology of software clustering to web-based application, which is one of web engineering, is strongly needed. In this paper, we propose a Form Clustering Algorithm along with an application example, which are used for internal-system reengineering to web-based information system. A Form Clustering Algorithm focuses on Page-model which is the feature of the web among the various web-based information system's structural model. Specially, we applying distance matrix to navigation model of graph form for easily analyzing, and web log analysis for identifying core function object that have a highly loading. Also, we create web software structure that can be used to maximize reusability and assign hardware effectively through 2-phase clustering step. Form Clustering Algorithm might be used at web-based information system development and maintenance for reusable web component development and hardware assignment, respectively.

• Korean Journal of Social Welfare Studies
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• no.37
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• pp.429-455
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• 2008

The purpose of this study is to generate a substantive theory that accounts for the social readaptation of the women who have engaged in prostitution and propose a practical program for them. We used the grounded theory developed by Strauss and Corbin(1990). Raw data were collected through the in-depth interview, documents and observation. We used constant comparative method for the data analysis. The nine women who had the exprience of prostitution have participated in this study. As a result of the data analysis, in open coding were generated 116 concepts, 29 subcategories and 12 categories, In axial coding the outcomes of a paradigm model were as follows. The causal conditions were named 'hostile environment' and 'the self endowed stigma'. The phenomenon turned out to be 'living as an anonymous being'. The contextual conditions were named 'cohesion of family', 'being pushed' and 'shrinked emotion'. The intervening conditions were presented to be 'desire of self restoration as a social being', 'reactionary reconstruction'. The action/interaction strategies turned out to be 'shifting of social status', 'neighbor alliance'. The consequences were presented to be 'psychological wayfarer' and 'tentacular living'. In selective coding we found a core category, 'repetition of leaving and returning from the life world'. Based on the phenomenon, two types of participants life attitudes were found as follows : present hesitating type, self concealing type. Following the adove results, We finally suggested the need to develope a community oriented case management model.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.243-248
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• 1998

This study investigated the separation and the property of palladium precipitate formed by ascorbic acid in a simulated radioactive liquid waste, which was composed of 10 elements((Pd, Ru, Rh, Nd, Cs, Sr, Fe, Ni, Zr, Mo). Pd was separated selectively by using reduction characteristics of metal ions contained in the simulated waste with ascorbic acid. When the nitric acid concentration was 0.5 M, the Pd over 99.5% was precipitated by adding 0.04 M ascorbic acid. Nitric acid concentration is important at the reduction reaction of Pd ion. The precipitation yield of Pd was decreased as the concentration of nitric acid was increased. The Pd precipitate was re-dissolved in reaching at an equilibrium when the concentration of nitric acid was high and ascorbic acid was added with a small amount. The Pd precipitate formed by ascorbic acid was Pd metal and was aggregated by particles less than $1.0{\mu}m$.