• 한국토양비료학회지
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• 제45권3호
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• pp.410-420
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• 2012

The heavy reliance on fossil fuels, especially oil and gas has triggered the global energy crisis. Continued use of petroleum fuels is now widely recognized as unsustainable because of their depleting supplies and degradation to the environment. To become less dependent on fossil fuels, current world is shifting paradigm in energy by developing alternative energy sources mainly through the utilization of renewable energy sources. In particular, bioenergy recovery from wastes with the help of microorganism is viewed as one of the promising ways to mitigate the current global warming crisis as well as to supply global energy. It has been proved that microorganism can generate power by converting organic matter into electricity using microbial fuel cells (MFCs). MFC is a bioelectrochemical device that employs microbes to generate electricity from bio-convertible substrate such as wastewaters including municipal solid waste, industrial, agriculture wastes, and sewage. Sustainability, carbon neutral and generation of renewable energy are some of the major features of MFCs. However, the MFC technology is confronted with a number of issues and challenges such as low power production, high electrode material cost and so on. This paper reviews the recent developments in MFC technology with due consideration of electrode materials used in MFCs. In addition, application of biocathodes in MFCs has been discussed.

• 대한기계학회논문집B
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• 제33권5호
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• pp.299-310
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• 2009

Fuel cells are expected to be promising future power sources in both aspects of thermal efficiency and environmental friendliness. Accordingly, worldwide research and development efforts have been enormously increasing recently in various applications such as power plants, transportation and portable power sources. Among others, high temperature fuel cells, such as solid oxide fuel cells and molten carbonate fuel cells, are suitable for electric power plants. Moreover, their high operating temperature is quite appropriate to construct further advanced integrated systems. This paper reviews recent literatures on research and development of integrated power generation systems based on high temperature fuel cells. Research and development efforts are summarized in the area of fuel cell/ gas turbine hybrid systems, application of carbon capture technology to fuel cell systems, integration of coal gasification with fuel cells, and the use of alternative fuels.

• 한국식품영양과학회지
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• 제27권1호
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• pp.51-56
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• 1998

A bacteium, KP-6408, capable of hydrolyzing fibrin was isolated from Chungkook-jang, which was possibly identified as a strain of Bacillus sp. The effects of culture condition and medium composition on the enzyme production were investigated. Among nitrogen sources tested, yeast extract was the most effective for the enzyme production, and the level of the concentration for the optimal enzyme production was 0.2%(w/v). For carbon sources, glucose was the best for the enzyme production with the level of 2.0%(w/v). The enzyme was maximally produced by cultivating the enzyme production with the level of 2.0%(w/v). The enzyme was maximally produced by cultivating the organism at the liquid medium of the initial pH 8.0 and temperature of 4$0^{\circ}C$. In Chungkook-jang fermentation, the enzyme was maximally produced when incubated at 35$^{\circ}C$ for 24 hrs using soybean as a solid medium. The addition of various rice starch to the soybean in Chungkook-jang fermentation lowered the enzyme production.

• 한국식품과학회지
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• 제20권1호
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• pp.79-84
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• 1988

대두(大豆)중에 존제하는 장내(腸內) 가스 발생인자인 raffinose와 stachyose의 제거에 이용될 수 있는 Aspergillus niger의 ${\alpha}$-galactosidase는 Czapeck-Dox 액체배지와 밀기울 배지에서 5일간 배양하였을 때 효소생성이 제일 높았다. Czapeck-Dox 액체배양에서 raffinose와 $NaNO_3$가 효소생산에 가장 효과적인 탄소원과 질소원으로 나타났으며 밀기울 배양에서는 질소원 또는 탄소원의 첨가효과가 없었다. 생성된 조효소(組酵素)용액의 작용 최적 pH는 4.0-5.0, 안정도 최적 pH는 3.5-6.5, 최적온도는 $40-50^{\circ}C$ 였다. 합성기질인 p-nitrophenyl-${\alpha}$-D-galactoside에 대한 Michaelis상수는 0.42mM, 최대반응속도는 152${\mu}moles$ substrate/min/kg (고체배지)이었다. $HgCl_2$는 강력한 비경쟁 저해제로 작용하였고 p-chloromercuribenzoate는 낮은 농도에서 경쟁 저해제로 작용하였다. 조효소 용액은 raffinose와 stachyose를 완전 분해하여 단당류 만을 생성하였다.

• Journal of Biosystems Engineering
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• 제41권2호
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• pp.75-84
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• 2016

Purpose: In-situ water quality monitoring based on ion-selective electrodes (ISEs) is a promising technique because ISEs can be used directly in the medium to be tested, have a compact size, and are inexpensive. However, signal drift can be a major concern with on-line management systems because continuous immersion of the ISEs in water causes electrode degradation, affecting the stability, repeatability, and selectivity over time. In this study, a computer-based nitrate monitoring system including automatic electrode rinsing and calibration was developed to measure the nitrate concentration in water samples in real-time. Methods: The capabilities of two different types of poly(vinyl chloride) membrane-based ISEs, an electrode with a liquid filling and a carbon paste-based solid state electrode, were used in the monitoring system and evaluated on their sensitivities, selectivities, and durabilities. A feasibility test for the continuous detection of nitrate ions in water using the developed system was conducted using water samples obtained from various water sources. Results: Both prepared ISEs were capable of detecting low concentrations of nitrate in solution, i.e., 0.7 mg/L $NO_3-N$. Furthermore, the electrodes have the same order of selectivity for nitrate: $NO_3{^-}{\gg}HCO_3{^-}$ > $Cl^-$ > $H_2PO_4{^-}$ > $SO{_4}^{2-}$, and maintain their sensitivity by > 40 mV/decade over a period of 90 days. Conclusions: The use of an automated ISE-based nitrate measurement system that includes automatic electrode rinsing and two-point normalization proved to be feasible in measuring $NO_3-N$ in water samples obtained from different water sources. A one-to-one relationship between the levels of $NO_3-N$ measured with the ISEs and standard analytical instruments was obtained.

• 한국입자에어로졸학회지
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• 제20권1호
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• pp.13-24
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• 2024

The concentrations of polycyclic aromatic hydrocarbons (PAHs) and elemental carbon (EC) in particulate matter, typical primary aerosols have decreased in Seoul between 2003 and 2018 (80% for PAHs and 85% for EC). The yearly mean benzo[a]pyrene (BaP) concentration has been lower than 1 ng/m3 since 2010-2011, the target value set by the European Union (EU) and China. A series of policies related to solid fuel and vehicle in South Korea and China should be effective in the reduction of the ambient PAHs and EC concentrations. But the emission data of PAHs and EC at both countries did not support that hypothesis. Possible causes are uncertainties in the emission inventories of primary carbonaceous aerosols in South Korea and China, although there may be a minor effect of the emissions from North Korea on the concentrations in Seoul. Thus the further policy directions against PAHs and EC such as improvements of emissions inventories and measurements, intensive regulation of non-road mobile sources and control of PAHs derivatives are discussed.

• Applied Biological Chemistry
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• 제10권
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• pp.101-105
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• 1968

C 원(源)과 N 원(源)으로써 glucose와 casamino acid를 사용(使用)하여 당농도(糖濃度)와 N 농도(濃度)의 차이(差異)가 Zygosacch. bisporus, Zygosacch. debrueckii, Zygosacch. steiner: 의 포자형성(胞子形成) 및 증식(增殖)과 life cycle에 미치는 영향(影響)에 대(對)하여 시험검토(試驗檢討)하였다. 1. 포자형성최적농도(胞子形成最適濃度)는 N $0{\sim}0.001%$ 당(糖) $10{\sim}20%$이며 N농도(濃度) 0.04%에 있어서는 포자(胞子)를 전(全)혀 형성(形成)하지 않고 0.01% 이하(以下)의 농도(濃度)에 있어서 포자(胞子)를 형성(形成)하게 된다. 2. 증식최적농도(增殖最適濃度)는 N 0.04% 당(糖) $5{\sim}10%$이다. 3. Zygosacch.의 일반적(一般的)인 life cycle은 포자(胞子)${\to}$영양세포(榮養細胞)${\to}$접합(接合)${\to}$포자형성(胞子形成)의 각(各) 단계(段階)를 경유(經由)하나 Zygosacch. bispolus의 zygote를 증식(增殖)에 최적(最適)의 N 농도(濃度) 0.04%의 배지(培地)에 이식(利殖)하였을때 곧 포자(胞子)를 형성(形成)하지 않고 다시 영양번식(榮養繁殖)하며 영양조건(榮養條件) 특(特)히 N 농도(濃度)에 의해서 diploid zygote의 영양번식(榮養繁殖)이 유도된다.

• 한국식품영양학회지
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• 제17권2호
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• pp.177-185
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• 2004

국내에서 재배되고 있는 번데기동충하초의 배양조건과 영양원이 균사체의 생육과 단백다당류 생성에 미치는 영향을 조사한 결과는 다음과 같다. 탄소원에 따른 단백다당류의 생성량은 균체와 배양액에서 glucose, sucrose, 전분의 순으로 30mg/100$m\ell$ 이상의 생성량을 보였다. 또한 탄소원에 따른 단백다당류를 구성하는 단당류의 조성은 크게 달라졌다. 탄소원과 질소원에 따른 단백다당류의 생성은 glucose와 peptone에서 가장 높았으며 탄소원과 질소원의 비율(C/N비)은 glucose 3%에 peptone 0.5%의 함량이 균체의 증식이나 단백다당류 생성에 가장 좋았다. 단백다당류의 생성량은 균사체 내에서는 진탕 배양에 의해 현저하게 증가하였으며 배지의 산도는 pH 4.5에서 최적을 보였으며 최적배양온도는 $25^{\circ}C$이었다. DPPH 법으로 측정한 단백다당류의 항산화능을 측정한 결과, 번데기를 이용한 고체배양보다 액체배양에서 더 높은 전자공여능을 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제32권4호
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• pp.430-436
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• 2022

Platycosides, Platycodi radix (Platycodon grandiflorus root) saponins, are used as food supplements and exert diverse pharmacological activities. Deglycosylation of saponins enhances their biological efficacy, and deglycosylated platycosides are produced mainly through enzymatic hydrolysis. However, the types of available deglycosylated platycosides remain limited because of a lack of hydrolyzing enzymes that can act on specific glycosides in glycosylated platycosides. In this study, a crude enzyme from Aspergillus tubingensis converted platycoside E (PE) and polygalacin D₃ (PGD3) into deglucose-apiose-xylosylated (deGAX)-platycodin D (PD) and deGAX-polygalacin D (PGD), respectively. The products were identified through LC/MS analysis by specifically hydrolyzing all glucose residues at C-3, and apiose and xylose residues at C-28 of platycoside. The hydrolytic activity of the crude enzyme obtained after the cultivation of the fungus using citrus pectin and corn steep solid as carbon and nitrogen sources, respectively, in culture medium was increased compared with those using other carbon and nitrogen sources. The crude enzyme from A. tubingensis was the most effective in producing deGAX platycoside at pH 5.0 and 60℃. The crude enzyme produced 0.32 mg/ml deGAX-PD and 0.34 mg/ml deGAX-PGD from 1 mg/ml PE and 1 mg/ml PGD3 (at pH 5.0 and 60℃) for 12 and 10 h, with productivities of 32.0 and 42.5 mg/l/h and molar yields of 62.1 and 59.6%, respectively. To the best of our knowledge, this is the first study to produce deGAX platycosides from glycosylated platycosides.

• 한국세라믹학회지
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• 제50권5호
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• pp.309-318
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• 2013

Graphene has attracted considerable attention since its first production from graphite in 2004, due to its outstanding physical and chemical properties. The development of production methodsfor large scale, high quality graphene films is an essentialstep toward realizing graphene applications such as transparent, conductive film. Chemical deposition methods, using metal catalystsand gaseous carbon sources, have been extensively developed for large area synthesis. In this paper, wereview recent progress ingraphene production, and survey the role of graphene electrodes in various electronic devices such as touch panels, solar cells, solid statelighting and microelectronic devices.