• Food Science and Biotechnology
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• v.17 no.4
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• pp.772-779
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• 2008

The antioxidative effect of doenjang (fermented soybean paste) and onion added in the seasoned pork, bulgogi was evaluated and the optimum mixture ratio of ingredients in seasoning sauce has been established using mixture experimental design (MED). When the seasoned pork, bulgogi was prepared with soy sauce 12% (control), doenjang 9% (in replacement of soy sauce 9%) added group (DG), and doenjang 9% and onion 33.4% (in replacement of water 33.4%) added group (DOG), and stored at $-25^{\circ}C$ for 6 months, the peroxide value (POV) and thiobarbituric acid (TBA) value of control, DO, and DOG were all lower than that of control from the initial stage of storage. The antioxidative effect of seasoned pork was found to increase with the replacement of doenjang in seasoning sauce for pork bulgogi. Moreover, antioxidative effects in DOG increased more synergistically. Therefore, the lipid oxidation stability of pork bulgogi was improved by the addition of doenjang and onion onto the seasoning sauce. The optimum mixture ratio of seasoning sauce for pork bulgogi followed up by the MED was found to be doenjang 7.10%, soy sauce 9.46%, onion 19.72%, and water 42.58% with excellent sensory quality.

• Korean Journal of Materials Research
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• v.30 no.1
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• pp.14-21
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• 2020

Carbon supports for dispersed platinum (Pt) electrocatalysts in direct methanol fuel cells (DMFCs) are being continuously developed to improve electrochemical performance and catalyst stability. However, carbon supports still require solutions to reduce costs and improve catalyst efficiency. In this study, we prepare well-dispersed Pt electrocatalysts by introducing titanium dioxide (TiO₂) into biomass based nitrogen-doped carbon supports. In order to obtain optimized electrochemical performance, different amounts of TiO₂ component are controlled by three types (Pt/TNC-2 wt%, Pt/TNC-4 wt%, and Pt/TNC-6 wt%). Especially, the anodic current density of Pt/TNC-4 wt% is 707.0 mA g^-1_pt, which is about 1.65 times higher than that of commercial Pt/C (429.1 mA g^-1_pt); Pt/TNC-4wt% also exhibits excellent catalytic stability, with a retention rate of 91 %. This novel support provides electrochemical performance improvement including several advantages of improved anodic current density and catalyst stability due to the well-dispersed Pt nanoparticles on the support by the introduction of TiO₂ component and nitrogen doping in carbon. Therefore, Pt/TNC-4 wt% may be electrocatalyst a promising catalyst as an anode for high-performance DMFCs.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1335-1341
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• 1988

A pH-ISEFET microprobe for in vivo measurements has been fabricated by combining ISFET (SL-IIS) chip and capillary thin film reference electrode. A two-step TCE oxidation for the gate oxide layer and multilayer encapsulation using silicone rubber and epoxy were specially used for the improvement of the stability and temperature dependence of the ISFET's. The measured sensitivit, response time and temperature dependence of the pH-ISFET microprobes are 50 mV/pH, less than one second, and - 0.01 pH/$^{\circ}$ , respectively. By operating continuously more than 40 days, a long term stability of 0.016 pH/day is obtained. The result of pH monitoring of femoral arterial blood in a rabbit is fairly good agreement with the value of blood gas analysis.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.675-678
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• 2003

본 논문에서는 N-type 기판에서 Nickel-Silicide를 적용하였을 경우에 나타나는 문제점과 PAI (Pre-amorphization Implant)의 효과에 대하여 알아보았다. N-type 기판에 RTP (Rapid Thermal Process)를 통하여 Nickel-Silicide 를 형성하게 되는데, 여기까지는 안정한 Nickel mono-Silicide (NiSi)가 형성됨을 확인하였다. 하지만 후속 열처리 공정 후 심한 응집 현상 (Agglomeration)과 이상 산화 현상 (Abnormal Oxidation Phenomenon), Silicide Island 등 열안정성 (Thermal Stability) 측면에서 여러 가지 많은 문제점들이 나타났다. 이 후속 열처리의 열안정성 취약점들을 극복하는 방안으로 Ge 및 N₂ PAI를 적용하였다. PAI를 적용하였을 경우에는 그렇지 않은 경우에 비하여 고온 열처리 후에도 면저항이 비교적 잘 유지되었으며, 두께가 얇고 안정한 Nickel-Silicide 특성을 확보할 수 있었다. 특히 Ge PAI 에 비하여 N₂ PAI 의 경우가 보다 특성 개선 효과가 크게 나타났다.

• Journal of Hydrogen and New Energy
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• v.23 no.6
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• pp.640-646
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• 2012

The effect of Ce promotion over 1wt% $Pt/{\gamma}-Al_2O_3$ catalysts on the CO conversion and $CO_2$ selectivity was investigated in preferential CO oxidation (PrOx) to reduce the CO concentration less than 10 ppm in excess $H_2$ stream for polymer electrolyte membrane fuel cell (PEMFC). Ce-promoted 1wt% $Pt/{\gamma}-Al_2O_3$ catalysts were prepared by incipient wetness impregnation method and the loading amount of Pt was fixed at 1wt%. The content of Ce promoter which has excellent oxygen storage and transfer capability due to the redox property was adjusted from 0 to 1.5wt%. Ce-promoted 1wt% $Pt/{\gamma}-Al_2O_3$ catalysts exhibit high CO conversion and $CO_2$ selectivity at low temperatures below $150^{\circ}C$ due to the improvement of reducibility of surface PtOx species compared with the 1wt% $Pt/{\gamma}-Al_2O_3$ catalyst without Ce addition. When Ce content was more than 1wt%, the catalytic activity was decreased at over $160^{\circ}C$ in PrOx because of competitive $H_2$ oxidation. As a result, 0.5wt% Ce is optimal content not only to achieve high catalytic activity and good stability at low temperatures below $150^{\circ}C$ in the presence of $CO_2$ and $H_2O$ but also to minimize the $H_2$ oxidation at high temperatures.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.802-807
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• 2015

In this study, we synthesized a new biocatalyst consisting of glucose oxidase (GOx), polyethyleneimine (PEI) and carbon nanotube (CNT) with addition of terephthalaldehyde (TPA) (TPA/GOx/PEI/CNT) for fabrication of glucose sensor that shows improved sensing ability and stability compared with that using other biocatalysts. Main bonding of the new TPA/GOx/PEI/CNT catalyst is formed by Aldol condensation reaction of functional end groups between GOx/PEI and TPA. Such formed bonding structure promotes oxidation reaction of glucose. Catalytic activity of TPA/GOx/PEI/CNT is evaluated quantitatively by electrochemical measurements. As a result of that, large sensitivity value of $41{\mu}Acm^{-2}mM^{-1}$ is gained. Regarding biosensor stability of TPA/GOx/PEI/CNT catalyst, covalent bonding formed between GOx/PEI and TPA prevents GOx molecules from becoming leaching-out and contributes improvement in biosensor stability. With estimation of the biosensor stability, it is found that the TPA/GOx/PEI/CNT catalyst keeps 94.6% of its initial activity even after three weeks.

• New & Renewable Energy
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• v.19 no.4
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• pp.27-34
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• 2023

In this study, microalgal oil was extracted from Nannochloropsis oceanica cultured in an open raceway pond and converted into biodiesel using a solid acid catalyst. Microalgal oil was extracted from two types of microalgae with and without nitrogen starvation using the KOH-solvent extraction method and the fatty acid content and oil extraction yield from each microalgae were compared. The fatty acid content of N. oceanica was 184.8 mg/g cell under basic conditions, and the oil content increased to 340.1 mg/g under nitrogen starvation conditions. Oil extraction yields were 90.8 and 95.4% in the first extraction, and increased to 97.5 and 98.8% after the second extraction. Microalgal oil extracted by KOH-solvent extraction was yellow in color and had reduced viscosity due to chlorophyll removal. In biodiesel conversion using the catalyst SO₄^2-/HZSM-5, solvent-extracted oil showed a FAME content of 4.8%, while KOH-solvent-extracted oil showed a FAME content of 90.4%. Solid acid catalyst application has been made easier by removal of chlorophyll from microalgal oil. The FAME content increased to 96.6% upon distillation, and the oxidation stability increased to 11.07 h with addition of rapeseed biodiesel and 1,000 ppm butylated hydroxyanisole.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.178.2-178.2
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• 2011

바이오디젤이란 식물성 기름, 동물성 지방, 폐식용유 등의 재생 가능한 자원을 촉매 존재 하에 알코올과 반응시켜 생성되는 에스테르 혼합물을 말하며 경유와 물성이 유사하므로 경유에 혼합하여 압축착화 방식인 디젤엔진에 사용할 수 있다. 그러나 바이오디젤은 경유에 비하여 탄소-탄소 간 이중결합을 가지고 있는 성분을 많이 함유하고 있기 때문에 공기에 의해 산화가 일어나기 쉽다. 일반적으로 폐놀계 향산화제인 t-buthylhydroquinone(TBHQ)를 사용하여 산화안정성을 향상시키나 국내에서 사용되는 산화방지제는 전량 수입에 의존하고 있어 제품 개발에 의한 국산화가 시급한 실정이다. 본 연구에서는 폐유지로부터 생산한 바이오디젤의 산화안정성 향상을 위하여 폐놀 및 아민계 등의 산화방지제를 합성하여 바이오디젤에 적용하였으며, 다양한 물성시험방법을 적용하여 석유 및 석유대체연료 사업법에서 규정하는 바이오디젤의 품질기준을 확인하였다. 또한 EN 14112 바이오디젤 산화안정성 시험방법으로 폐놀 및 아민계 등의 산화안정성을 확인하였다. 본 연구는 산학연 공동기술개발 1차년도 사업으로 한국화학연구원과 공동으로 수행하였으며, 산화방지제 적용평가를 통해 우수한 제품을 선정하여 2차년도에는 차량 테스트를 통해 연료 첨가제로서의 적합성을 검증할 예정이다.

• YAKHAK HOEJI
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• v.39 no.5
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• pp.495-505
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• 1995

The O/W microemulsion systems were made from 2 or 4% (w/w) oil (soybean oil, olive oil or isopropyl myristate) and 10, 15 or 20% (w/w) Brij 96. They were compared with micellar solution of equivalent surfactant concentration m therms of physicochemical properties, and the solubilization of sudan IV. They were characterized by dynamic light scattering, stability, surface tension, viscosity and rheogram. The mean diameters of O/W microemulsion systems were 10-15nm, and those of Brij 96 micellar solutions were 18-19 nm. Both of them were monodisperse systems. The O/W microemulsion systems showed Newtonian flow and their apparent viscosities were lower than those of micellar solutions. The surface tensions of O/W microemulsion systems were increased or decreased depending on the types of oil used, when compared with those of micellar solutions. The O/W microemulsion systems were very stable, and did not show any flocculation or aggregation. Their mean diameters were not changed after three months. But oxidation was observed in microemulsions without nitrogen gas at high temperature. There was a significant improvement in the sudan IV solubffimtion in micromulsion compared with that m the micellar solution containing equivalent concentration of surfactant. The size distribution and mean diameters of O/W micromulsions were not changed when sudan IV was solubilized.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.133-140
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• 2002

Catalytic combustion known as one of the traditional oxidation methods of VOC gas is restricted to its applicable fields because of its reaction characteristics. But recently innovative improvement of catalytic endurance makes its applicable range broader from MEMs to industrial power generation. Therefore, control technologies based on the catalytic combustion characteristics are researched and developed dynamically. Especially, the stable control of catalytic combustion is an essential factor in a view of maximizing its efficiency. In this research, the fuel equivalence ratio and the preheating temperature of mixture gas is controlled by catalytic combustion system enhanced in heat transfer with high temperature heat exchanger. As a result the combustion characteristics of system was investigated, and both passive and active control type were compared and analyzed.