• Polymer(Korea)
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• v.35 no.3
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• pp.254-259
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• 2011

In electrospraying of polymer solutions, metal sample collectors are often ineffective in fully removing solvent from sprayed particles and recovering redispersable sprayed particles. Herein, a novel electro spraying system, where sprayed particles were dispersed into laminar flow of dispersant (coagulation liquid), was designed for the nano-encapsulation of protein drugs. Chitosan and polyacrylic acid were used as the encapsulation materials. Aggregation of particles could be prevented by using this new electrospraying system, and unimodal size distribution was observed at an applied voltage between 4~16 kV and a low flow rate. The effects of the applied voltage on mean particle size were not significant on the other hand.

• Communications of Mathematical Education
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• v.37 no.4
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• pp.569-590
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• 2023

The purpose of this case study is to compare and analyze the covariational reasoning levels of two middle school students revealed in the process of solving and generalizing algebra word problems. A class was conducted with two middle school students who had not learned quadratic equations in school mathematics. During the retrospective analysis after the class was over, a noticeable difference between the two students was revealed in solving algebra word problems, including situations where speed changes. Accordingly, this study compared and analyzed the level of covariational reasoning revealed in the process of solving or generalizing algebra word problems including situations where speed is constant or changing, based on the theoretical framework proposed by Thompson & Carlson(2017). As a result, this study confirmed that students' covariational reasoning levels may be different even if the problem-solving methods and results of algebra word problems are similar, and the similarity of problem-solving revealed in the process of solving and generalizing algebra word problems was analyzed from a covariation perspective. This study suggests that in the teaching and learning algebra word problems, rather than focusing on finding solutions by quickly converting problem situations into equations, activities of finding changing quantities and representing the relationships between them in various ways.

• Elastomers and Composites
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• v.49 no.4
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• pp.284-292
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• 2014

Polymer has low mechanical strength than metal. In particular, the impact strength is very weak. Impact modifier reinforced polymers are frequently used. Impact strength of reinforced polymer is changed according to content and distribution of impact modifier. In this study, izod impact test has been simulated to analyze the mechanism of impact modifier reinforced Nylon 6. Computational results were compared for numbers and distributions of impact modifier. As the total volume of rubber particles decreased, the stress at the notch increased for the simulation model that the volume decreases as particle number increases. As the surface area of particle sphere increased, the stress and difference of principle stress increased for the simulation model that the total surface increases as particle number increases.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.30-30
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• 2011

산업화 과정에 방출된 할로겐 화합물 및 프레온 가스가 오존층을 파괴하면서 많은 양의 자외선이 지표에 도달하여 생태계에 적지 않은 영향을 끼치고 있다. 자외선은 살균, 소독작용 및 Vitamin D 합성을 위해 생명체에 필수적이지만 과다할 경우 색소침착, 피부노화, 피부암 발생, 백내장의 증가, 면역기능저하 등의 피해를 준다. 자외선은 파장 영역에 따라 UV-A(장파장 자외선), UV-B(중파장 자외선)및 UV-C(단파장 자외선)으로 나뉜다. 이 중 인체에 가장 유해한 것으로 알려진 단파장의 UV-C는 파장이 짧아 침투력이 미약해 오존층과 성층권에서 대부분 흡수되므로 생물학적으로 큰 의미는 없다. 그러나 자외선 중 UV-B와 UV-A 영역의 자외선은 인체에 영향을 가장 많이 미치므로 이들 영역의 자외선을 차단하는 것이 필요하다. Vitamin C는 아스코르브산(ascorbic acid)이라고도 불리며 미백효과, 주름 개선, 자외선 차단 및 항산화 작용을 하지만 섬유가공 시 Vitamin C는 쉽게 산화되며 세탁 내구성이 떨어지기 때문에 가교제를 필요로 한다. Vitamin C를 이용하여 자외선 차단성 섬유제품을 개발하기 위해, 포름알데히드를 유리하지 않는 폴리카르복시산 가교제 중 하나인 Citric Acid(CA)를 사용하여 고온에서 면직물에 처리했을 때 에스테르 형 가교를 형성하여 내세탁성을 가질 수 있었다. 자외선 차단 효과를 알아보기 위하여 KS K 0850 섬유제품의 자외선 차단율 및 차단지수 시험방법으로 평가하였다.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.167-174
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• 2022

The Ministry of Oceans and Fisheries promoted the installation of eel-ladder for the purpose of creating inland water resources. Currently, eel-ladder have been installed and operated at the Geumgang Estuary Bank (2018), Yeongam Embankment (2019), and Asanman Embankment (2020). In this study, the number of glass eels in eel-ladder in 2021 was monitored and factors affecting the rise that from ocean to river of eels were investigated. Glass eels in eel-ladder were found when the salinity was relatively low, and they started when the freshwater and seawater temperatures were above 20℃. Comparing the number of occurrences by year, the largest number of glass eels was observed in 2021, but it is judged that this is not according to the distribution of glass eels in sea, but rather as a result of the investigator's eel-ladder repair and guidance on illegal fishing.

• Journal of the Korean Geographical Society
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• v.37 no.4
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• pp.337-356
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• 2002

It was proven that the spatial distribution pattern of the parking lots in Cheongju city was clarified through the concentric expansion of the parking lots, which started out from the center for commercial and business function, into the periphery regions. First of ail, in terms of the spatial distribution pattern of the parking lot according to the operational subject, the parking lot is distributed through private, public, and parking lots attached to buildings in the center, and in its adjacent regions, public and parking lots attached to buildings are distributed. And public parking lot, private and parking lots attached to buildings are distributed in sector pattern. And in terms of facility structure, more than half of the parking lots attached to buildings in Cheongju city are composed of Parking lots of self-driver type. In the case of the center, regional structure of self-Parking type of parking lots attacked to buildings, self-parking type lots on plane street parking, mechanical parking types attached to buildings, self-parking type of plane non-street diversely appear to be combined types, its spatial facility distribution patterns appear to be concentric patterns. Also, in terms of the spatial distribution pattern of the parking lots according to the contact types, with the centralizing of a center, southwestern regions show hourly and monthly charged parking lots; northeastern regions show free parking lots. The spatial distribution pattern of the parking lots as above, reflects the regional distribution change of the establishment and residential location.

• Journal of Conservation Science
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• v.26 no.1
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• pp.85-94
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• 2010

Color stable hydrogenated bisphenol-A (HBA) epoxy adhesives containing organic-inorganic hybrid nanocomposites were prepared and investigated the properties. Isophorone-diamine (IPDA) was used as a hardener and polyhedral organomeric silsesquioxanes (POSS; EP0408 and EP0409) having epoxy function groups were used to tailor adhesives in the nanoscale range. The dependence of the concentration of different nano materials were studied since the large surface area of the nanosized particles can cause significant changes in properties of adhesives. HBA-IPDA adhesives containing different amount of nanomaterials have been applied to the fresh Namsan granite and compared with those of commercial adhesives, which have problems of color change as well as a high viscosity. The mechanical properties of HBA-IPDA containing POSSs are consistent with those of commercial adhesives in addition to the low viscosity.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.187-201
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• 2005

Bioprocessing technologies utilizing 'biorecognition' between a solid matrix and a protein is being widely experimented as a means to replacing the conventional, solution-based technology. Frequently the matrices are chromatographic resins with specific functional groups exposed outside. Since the reactions of and interactions with the proteins occur as they are attached to the solid matrix, this 'solid-phase' processing has distinct advantages over the solution-phase technology. Solid-phase refolding of inclusion body proteins uses ion exchange resins to adsorb denaturant-dissolved inclusion body. As the denaturant is slowly removed from the micromoiety around the protein, it is refolded into a native, three-dimensional structure. Once the refolding is complete, the folded protein can be eluted by a conventional elution technique such as the salt-gradient. This concept was successfully extended to 'EBA (expanded bed adsorption)-mediated refolding,' in which the denaturant-dissolved inclusion body in whole cell homogenate is adsorbed to a Streamline resin while cell debris and other impurity proteins are removed by the EBA action. The adsorbed protein follows the same refolding steps. This solid-phase refolding process shows the potential to improve the refolding yield, reduce the number of processing steps and the processing volume and time, and thus improve the overall process economics significantly. In this paper, the experimental results of the solid-phase refolding technology applied to several biopharmaceutical proteins of various types are presented.

• Journal of The Korean Society of Clinical Toxicology
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• v.14 no.2
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• pp.100-106
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• 2016

Purpose: Beta blocker (BB) has been prescribed for anxiety and panic disorder. Patients intoxicated by psychiatric drugs have often been exposed to BB. Moreover, BB overdose has adverse effects including cardiovascular effects, which can be life-threatening. This study was conducted to identify the characteristics of BB intoxication with psychiatric drugs and the adverse effects on the cardiovascular system. Methods: A single center, retrospective study was performed from January 2010 to December 2015. A total of 4,192 patients visited the emergency department (ED) with intoxication, and 69 with BB intoxication were enrolled. Results: Overall, 64 patients (92.8%) of enrolled patients were intoxicated with drugs prescribed for the purpose of psychiatric disorders. Propranolol was the most common BB (62 cases, 96.2%), and the median dose was 140.0 mg (25%-75% 80.0-260.0). Twenty-four patients (37.5%) had experienced cardiovascular events, and these patients tended to have decreased mentality, hypotension and coingestion with quetiapine. An initial mean arterial pressure (MAP) below 65 mmHg (odds ratio 10.069, 95% confidence interval 1.572-64.481, p=0.015) was identified as a factor of cardiovascular event upon multiple logistic regression analysis. Conclusion: Initial MAP below 65 mmHg was a factor of cardiovascular adverse effect in patients of BB intoxication with psychiatric drugs.

• Korean Journal of Materials Research
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• v.17 no.6
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• pp.318-322
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• 2007

Porous ${\beta}-tricalcium$ phosphate $({\beta}-TCP)$ bioceramic was fabricated by pressureless sintering using commercial HAp and different volume percentages of PMMA powders (30-60 vol.%). The range of spherical pore size was about $200-250\;{\mu}m$ in diameter. By increasing the PMMA content, the number of pores and their morphology were dramatically changed as well as decreased the material properties. In case of using 60 vol.% PMMA content, network-type pores were found, due to the necking of the PMMA powders. The values of relative density, elastic modulus, bending strength and hardness of the 60 vol.% PMMA content sample, sintered at $1500^{\circ}C$, were about 46%, 22.2 GPa, 5MPa and 182 Hv respectively. Human osteoblast-like MG-63 cells and osteoclast-like Raw 264.7 cells were well grown and fully covered all of the porous ${\beta}-TCP$ bodies sintered at $1500^{\circ}C$.