• 환경생물
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• 제37권4호
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• pp.741-748
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• 2019

본 연구에서는 바이오매스 폐기물인 Corynebacterium glutamium을 Alg를 이용한 고정화와 PEI 표면개질 과정을 통하여 유해 미세조류인 Microcystis aeruginosa를 제거할 수 있는 흡착소재인 PEI-AlgBF를 개발하였다. 녹조의 발생단계에 상관없이 PEI-AlgBF는 수계로부터 M. aeruginosa를 성공적으로 제거할 수 있었으며 유해조류 제거과정에서 M. aeruginosa 세포의 파괴를 유발하지 않았다. 흡착소재의 표면적은 M. aeruginosa의 제거효율에 매우 큰 영향을 주는 주요인자로 확인할 수 있었다. PEI-AlgBF를 사용한 M. aeruginosa 흡착/제거 방식은 기존 기술에 비하여 환경영향성이 낮기 때문에 보다 안전하고 안정적인 유해조류의 제어 방식이 될 것이다.

• Composites Research
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• 제36권2호
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• pp.126-131
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• 2023

기존의 상용 플라스틱으로 인한 환경 오염에 대한 우려가 높아지면서 대체 재료로서 생분해성 고분자에 대한 연구가 주목을 받고 있다. 본 연구는 생분해성 열가소성 수지인 폴리 젖산에 유기 핵제의 도입으로 물성 강화 및 100% 생분해 가능한 나노복합재 개발을 목표로 한다. 그에 따라 무기 핵제의 대체재로 친환경 소재인 셀룰로오스 나노섬유를 채택하였다. 폴리 젖산 내 셀룰로오스 나노섬유의 균일한 분산을 위해 동결 건조 방식으로 나노화된 섬유 형상을 유지시켰으며, 이축압출기로 1차 교반을 진행하고, 사출 성형을 통해 이중 교반된 물성 시험용 시편을 제작하였다. 보강된 결정성을 확인하기 위해 시차주사 열량분석법을 사용하였고 1 wt%의 셀룰로오스 나노섬유가 보강재 및 핵제로서 작용하여 냉결정화온도가 약 14℃ 가량 감소하며, 결정화되는 정도 또한 증가한 것을 확인하였다. 본 연구는 기존 생분해성 고분자의 무기 핵제를 유기 나노소재로 대체함으로써 100% 생분해 가능한 친환경 나노복합재 개발하여 강화된 물성의 플라스틱 소재 개발을 위한 친환경적 대안을 제시한다.

• 한국분말재료학회지
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• 제31권1호
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• pp.16-22
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• 2024

Composite-based piezoelectric devices are extensively studied to develop sustainable power supply and self-powered devices owing to their excellent mechanical durability and output performance. In this study, we design a lead-free piezoelectric nanocomposite utilizing (Ba_0.85 Ca_0.15)(Ti_0.9Zr_0.1)O₃ (BCTZ) nanomaterials for realizing highly flexible energy harvesters. To improve the output performance of the devices, we incorporate porous BCTZ nanowires (NWs) into the nanoparticle (NP)-based piezoelectric nanocomposite. BCTZ NPs and NWs are synthesized through the solid-state reaction and sol-gel-based electrospinning, respectively; subsequently, they are dispersed inside a polyimide matrix. The output performance of the energy harvesters is measured using an optimized measurement system during repetitive mechanical deformation by varying the composition of the NPs and NWs. A nanocomposite-based energy harvester with 4:1 weight ratio generates the maximum open-circuit voltage and short-circuit current of 0.83 V and 0.28 ㎂, respectively. In this study, self-powered devices are constructed with enhanced output performance by using piezoelectric energy harvesting for application in flexible and wearable devices.

• 한국재료학회지
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• 제20권9호
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• pp.472-477
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• 2010

$Al_2O_3$ has received wide attention with established use as a catalyst and growing application in structural or functional ceramic materials. On the other hand, the boehmite (AlO(OH)) obtained by sol-gel process has exhibited a decrease in surface area during phase transformation due to a decline in surface active site at high temperature. In this work, $Al_2O_3$-CuO/ZnO (ACZ) and $Al_2O_3$-CuO/CeO (ACC) composite materials were synthesized with aluminum isopropoxide, copper (II) nitrate hemi (pentahydrate), and cerium (III) nitrate hexahydrate or zinc (II) nitrate hexahydrate. Moreover, the Span 80 as the template block copolymer was added to the ACZ/ACC composition to make nano size particles and to keep increasing the surface area. The ACZ/ACC synthesized powders were characterized by Thermogravimetry-Differential Thermal analysis (TG/DTA), X-ray Diffractometer (XRD), Field-Emmision Scanning Electron Microscope (FE-SEM), Bruner-Emmett-Teller (BET) surface analysis and thermal electrical conductivity (ZEM-2:M8/L). An enhancement of surface area with the addition to Span 80 surfactant was observed in the ACZ powders from 105 $m^2$/g to 142 $m^2$/g, and the ACC powders from 103 $m^2$/g to 140 $m^2$/g, respectively.

• 한국산업정보학회논문지
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• 제13권4호
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• pp.24-34
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• 2008

이 연구는 모바일 비즈니스의 진화과정과 환경변화를 다각적이고 복합적으로 분석하여 향후 모바일콘텐츠 비즈니스의 진화방향을 예측함과 동시에 성공적인 전략을 도출하는데 그 목적이 있다. 결론적으로 모바일콘텐츠(MC) 비즈니스 모델은 세대를 거듭해가면서 영역이 확대되고, 그에 따른 사업자의 진출도 늘어남에 따라 복합적이고 다각적으로 변해 가면서 새로운 비즈니스 전략과제를 제시하고 있는데, 첫째, 고객접근성을 강화해야 하며, 둘째, 감성적으로 접근해야 하며, 개방적인 비즈니스 모델이 필요하다. 넷째, 소비자의 니즈를 반영한 콘텐츠의 기획 및 제작이 필요하며, 다섯째, 모바일플랫폼 선도형 콘텐츠군의 개발과 CP의 비즈니스모델 다양화가 요구된다. 산업정책 차원에서는 모바일콘텐츠 산업의 지속적인 발전을 위해서 단기적이고 단면적인 정책이 아닌, 지속가능한 미래 지향적인 정책이 마련되어야 한다. 건전하고 활기찬 모바일콘텐츠 생태계 조성을 위해서 정부와 규제기구는 모바일콘텐츠 시장의 주도자이기보다는 환경 조성자 역할에 충실하는 것이 바람직하다. 즉, 시장의 원활한 작동을 위한 기본적인 제도와 질서를 형성하고 관리하는데 주력해야 할 것이다.

• Journal of Electrochemical Science and Technology
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• 제9권3호
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• pp.229-237
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• 2018

The electrochemical sensing performance of metal-graphene hybrid based sensor may be significantly decreased due to the dissolution and aggregation of metal catalyst during operation. For the first time, we developed a novel large-area high quality three dimensional graphene foam-incorporated gold nanoparticles (3D-GF@Au) via chemical vapor deposition method and employed as free-standing electrocatalysis for non-enzymatic electrochemical glucose detection. 3D-GF@Au based sensor is capable to detect glucose with a wide linear detection range of $2.5{\mu}M$ to 11.6 mM, remarkable low detection limit of $1{\mu}M$, high selectivity, and good stability. This was resulted from enhanced electrochemical active sites and charge transfer possibility due to the stable and uniform distribution of Au NPs along with the enhanced interactions between Au and GF. The obtained results indicated that 3D-GF@Au hybrid can be expected as a high quality candidate for non-enzymatic glucose sensor application.

• The Journal of Asian Finance, Economics and Business
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• 제7권9호
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• pp.673-685
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• 2020

Financial literacy is one of the sustainable development goals of huge concern of governments. Governments explore solutions addressing policies to improve financial literacy. Nevertheless, financial management has such a broad scope and is not just limited to knowledge. As human nature, individuals are born with different confidence levels that include various financial abilities. This study aims to investigate the household-financial efficacy through the application of psychometric instruments, risk preference, and demographic characteristics toward consumption decision behavior. The research is based on a survey 479 households in the peninsular Malaysia, and utilizes the structural equation model, cluster proportional and systematic random sampling, and two measurements - composite reliability and average variance extracted. Results show that households' financial efficacy is one of the critical factors that explain the households' consumption decision behavior. Also, risk preference, gender and area location (rural or urban) of the household determined the consumption decision behavior of the household. The effectiveness of consumption decision is not only determined by financial literacy, but also financial efficacy. The implications of this paper may help to design policies in narrowing the broad gap between the rural and urban level of financial efficacy. The government needs to take appropriate actions to fix it.

• Journal of Microbiology and Biotechnology
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• 제27권11호
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• pp.2010-2018
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• 2017

Mixotrophic microalgal growth gives a great premise for wastewater treatment based on photoautotrophic nutrient utilization and heterotrophic organic removal while producing renewable biomass. There remains a need for a control strategy to enrich them in a photobioreactor. This study performed a series of batch experiments using a mixotroph, Chlorella sorokiniana, to characterize optimal guidelines of mixotrophic growth based on a statistical design of the experiment. Using a central composite design, this study evaluated how temperature and light irradiance are associated with $CO_2$ capture and organic carbon respiration through biomass production and ammonia removal kinetics. By conducting regressions on the experimental data, response surfaces were created to suggest proper ranges of temperature and light irradiance that mixotrophs can beneficially use as two types of energy sources. The results identified that efficient mixotrophic metabolism of Chlorella sorokiniana for organics and inorganics occurs at the temperature of $30-40^{\circ}C$ and diurnal light condition of $150-200{\mu}mol\;E{\cdot}m^{-2}{\cdot}s^{-1}$. The optimal specific growth rate and ammonia removal rate were recorded as 0.51/d and 0.56/h on average, respectively, and the confirmation test verified that the organic removal rate was $105mg\;COD{\cdot}l^{-1}{\cdot}d^{-1}$. These results support the development of a viable option for sustainable treatment and effluent quality management of problematic livestock wastewater.

• Archives of Plastic Surgery
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• 제44권4호
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• pp.324-331
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• 2017

Background Lipedema is a condition consisting of painful bilateral increases in subcutaneous fat and interstitial fluid in the limbs with secondary lymphedema and fibrosis during later stages. Combined decongestive therapy (CDT) is the standard of care in most countries. Since the introduction of tumescent technique, liposuction has been used as a surgical treatment option. The aim of this study was to determine the outcome of liposuction used as treatment for lipedema. Methods Twenty-five patients who received 72 liposuction procedures for the treatment of lipedema completed a standardized questionnaire. Lipedema-associated complaints and the need for CDT were assessed for the preoperative period and during 2 separate postoperative follow-ups using a visual analog scale and a composite CDT score. The mean follow-up times for the first postoperative follow-up and the second postoperative follow-up were 16 months and 37 months, respectively. Results Patients showed significant reductions in spontaneous pain, sensitivity to pressure, feeling of tension, bruising, cosmetic impairment, and general impairment to quality of life from the preoperative period to the first postoperative follow-up, and these results remained consistent until the second postoperative follow-up. A comparison of the preoperative period to the last postoperative follow-up, after 4 patients without full preoperative CDT were excluded from the analysis, indicated that the need for CDT was reduced significantly. An analysis of the different stages of the disease also indicated that better and more sustainable results could be achieved if patients were treated in earlier stages. Conclusions Liposuction is effective in the treatment of lipedema and leads to an improvement in quality of life and a decrease in the need for conservative therapy.

• Korean Chemical Engineering Research
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• 제60권1호
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• pp.70-79
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• 2022

Biodiesel production has attracted attention as a sustainable source of fuel and is a competitive alternate to diesel engines. The glycerol that is produced as a by-product is generally discarded as waste and can be converted to green chemicals such as acetins to increase bio-diesel profitability. Acetins find application in fuel, food, pharmaceutical and leather industries. Batch experiments and analysis have been previously conducted for synthesis of acetins using glycerol esterification reaction aided by sulfated metal oxide catalysts (SO₄^2-/CeO₂-ZrO₂). The aim of this study was to optimize process parameters: effects of mole ratio of reactants (glycerol and acetic acid), catalyst concentration and reaction temperature to maximize glycerol conversion/acetin selectivity. The optimum conditions for this reaction were determined using response surface methodology (RSM) designed as per a five-level-three-factor central composite design (CCD). Statistica software 10 was used to analyze the experimental data obtained. The optimized conditions obtained were molar ratio - 1:12, catalyst concentration - 6 wt.% and temperature -90 ℃. A packed bed reactor was fabricated and column studies were performed using the optimized conditions. The breakthrough curve was analyzed.