• 한국환경과학회지
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• 제11권2호
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• pp.111-120
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• 2002

Asian dust(or yellow sand) occurs mainly in spring and occasionally in winter in east Asia, when the weather conditions are under an upper trough/cut-off low and surface high/low pressure system during blocking episode days associated with the stationary patterns of the upper level jet stream. The transport mechanism for Asian dust during the blocking episode days in spring 2001 was analyzed using the TOMS aerosol index and meteorological mesoscale model 5(MM5). Based on the E vector, an extension of an Eliassen-Palm flux, the blocking episode days were found to be associated with the development of an upper cut-off low and surface cyclones. Concurrently, the occurrence of dust storms was also determined by strong cold advection at the rear of a jet streak, which exhibited a maximum wind speed within the upper jet stream. As such, the transport mechanism for Asian dust from China was due to advection of the isentropic potential vorticity(IPV) and isentropic surfaces associated with tropopause folding. The transport heights for Asian dust during the blocking episode days were found to be associated with the distribution of the isentropes below the IPV At the same time, lee waves propagated by topography affected the downward motion and blocking of Asian dust in China. The Asian dust transported from the dust source regions was deposited by fallout and rain-out with a reinforcing frontogenesis within a surface cyclone, as determined from satellite images using TOMS and GMS5. Accordingly, these results emphasize the importance of forecasting jet streaks, the IPV, and isentropes with geopotential heights in east Asia.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.714-720
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• 2011

Ethanol was used as reducing agent to remove $NO_x$ exhaust from the stationary source. Pre-treatment with sulfuric acid over $Ag/Al_2O_3$ catalyst was dedicated to overcome the $SO_2$ poisoning effect. The $NO_x$ reduction experiment was performed under the simulated condition of power plant The increased surface area with higher CPSI devoted to increase de-$NO_x$ yield. De-$NO_x$ yield of the $NO_x$ exhaust containing 20 ppm of $SO_2$ increased after acid treatment with 0.7% $H_2SO_4$ over 4.0% $Ag/Al_2O_3$, where the increased dispersion of Ag found from the results of XRD and XPS was the dominant factor for the increased de-$NO_x$ yield. However, the reason for the decreased de-$NO_x$ yield with the acid treatment of higher concentration (1.0% and 2.0%) of $H_2SO_4$ was found to be due to the formation of $Ag_2SO_4$ crystallites found from XRD result. Acid-treated $Ag/Al_2O_3$ catalyst showed maximum de-$NO_x$ yield at higher temperature than non-treated $Ag/Al_2O_3$ catalyst did.

• KSBB Journal
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• 제9권2호
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• pp.140-146
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• 1994

A. pullulans로부터 polyol 생산 특성을 검토하기 위하여 탄소원, 수분활성의 영향을 검토하였다. 생산된 polyol 중에서 mannitol이 주성분이었고 소량의 glycerol이 함께 생산되었다. 검토된 탄소원 중 sucrose, glucose, fructose, mannose를 단일 탄소원으로 사용하였을 때 mannitol을 생산할 수 있었으며, 20% sucrose 배지에서 polyol 생산량이 최대였고 이때 대당 mannitol의 수율($Yp_{p/s}$)은 0.227이었다 두 종류의 유용한 탄소원인 glucose와 sucrose에 대한 초기기질농도에 대한 $Yp_{p/s}$는 거의 일정한 값을 보여, 일반적인 내삼투성 미생물과는 달리 첨가된 염(NaCl, KCI)의 농도가 증가할수록, 즉 수분활성이 낮은 조건에서는 오히려 mannitol의 생산량이 낮아졌으며, 상대적으로, glycerol의 양은 증가하였다 실험결과를 종합해 볼 때, A. pullulans에 의한 polyol 중, glycer이의 경우는 다른 내삼투성 미생물의 경우와 같이 생산되지만, mannitol의 경우는 sucrose, glucose 등의 유용한 탄소원들의 대사과정 중에 인산화경로(phosphate pathway)과 환원효소작용(enzymatic dehydrogenation)을 통해 생성되는 발효산물 이라는 결론을 얻었다.

• 농업과학연구
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• 제21권1호
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• pp.60-66
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• 1994

하수 및 토양시료로부터 다수의 LAS분해세균을 분리하고 고농도 (LAS 200ppm)의 액체 배지에서 생육하면서 분해력이 높은 KL-3, SH-2, EN-1등 3개 균주를 선발하였다. 이들의 형태적, 생리적 및 배양적 성질에 따라 KL-3은 Klebsiella속, SH-2는 Shigella속, EN-1은 Enterobacter속 균주로 각각 동정되었다. 실험실용 발효조에서의 LAS의 분해양상은 배양초기에 분해속도가 빠르고 (1 일후의 분해율: KL-3 및 SH-2, 50%; EN-1, 20%), 배양 1-2일사이에서 그 속도가 크게 지연되다가 다시 분해가 빠르게 진행되며 3, 4일후에는 다시 늦어지는 경향을 나타내었다 (7일후의 분해율: KL-3, 85%; SH-2, 82%; EN-1, 75%). 균체의 생육은 배양 2일 후에 $10^8cfu/mL$수준의 정지기에 도달하였으며 pH는 최초 7.0에서 6.2~6.7의 범위로 저하되어 서서히 변화하는 경향이었다. 균체에 의한 LAS의 흡착량은 Shigella sp. SH-2균주의 경우가 가장 많았으며 Freund1ich흡착등식 Y= 0.030X + 0.95를 나타내었다.

• 한국해양바이오학회지
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• 제6권2호
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• pp.118-122
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• 2014

The ocean provide great benefits for microalgal mass cultures with maintaining stable temperature due to high specific heat, mixing by wave energy, and providing large area for large-scale microalgae cultures. In this study, we cultivated a marine green microalga, Tetraselmis sp. KCTC12432BP, using marine photobioreactors on the ocean for investigating the effect of $NaHCO_3$ concentration on the biomass productivities and evaluating the potential of ocean microalgae culture. The culture medium consist of three fold concentrated f/2-Si with 4 g/L of $NaHCO_3$, which is dissolved in natural seawater. After 11 days of cultivation, the cultures reached stationary phase at biomass concentration of 1.6 g/L. At that time, $NaHCO_3$ concentration of 0, 2, and 4 g/L were fed to the cultures. The daily productivities of 0.11, 0.19, 0.30 g/L/day were attained with feeding rate of 0, 2, and 4 g/L $NaHCO_3$, respectively. Biomass productivity of Tetraselmis sp. KCTC12432BP was a function of the $NaHCO_3$ feeding rate as expected. This research shows that the microalgae can grow with $NaHCO_3$ as carbon source in marine photobioreactors on the ocean while exploiting various benefits of ocean cultivation.

• 미생물학회지
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• 제19권2호
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• pp.63-77
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• 1981

The growth rate of yeast population (Saccharomyces uvarum) cultivated in the Knopp's modified medium (plus various carbon sources) appeared the highest value when the Knopp's minimal medium was treated to 1.5% with disaccharide such as maltose and sucrose. Also the treatment of lactose and raffinose resulted in polulation growth as to the population size in case of maltose and sucrose. However, the gorwth of yeast was not occurred at all when a polysaccharide, such as inulin, was added as carbon source. The growth from of yeast population in Knopp's modified medium are characterized by the fact that log phase continued 100hrs after inoculation and that stationary state phase appeared in general 250hrs after inoculation. Applying the various carbon sources to respiration substrate for yeast cell, the respiration rate of yeast showed the highest value in treatment of maltose and followed in order of raffinose, lactose, glucose, and sucrose. Determined the amount of poly-phosphate and turn over pathway of poly-phosphate according to culture phase of yeast, it is revealed that the yeast synthesized 3 types of poly phosphate (poly-P A,B, and C) and postulated that turn over pathway of poly-phosphate as follows ; Inorganic phosphate is converted into each kind of polyphosphates, and then one part of poly-P-C is converted into poly-P-B, the rest poly-p-C and poly-P-B are converted into poly-P-A. The synthesized poly-phosphate is considered to have a role as energy pool utilizing to synthesis of cellular organic materials. Of the 13 carbon sources used in this experiment, the useful carbon sources for biosynthesis of poly-phosphate and cellular organic materials are confirmed as disaccharide (maltose and sucrose) as well as glucose. Protein synthesis in yeast cell showed the two peaks on 6th and 8th day after inoculation ; nucleic acid on 2nd day (48hrs), carbohydrates on 2nd day (48hrs), and phospholipid on 2nd and 8th day after inoculation, respectively.

• 한국BIM학회 논문집
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• 제5권4호
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• pp.53-62
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• 2015

Korea has been at the forefront of green growth initiatives. In 2008, the government declared the new vision toward 'low-carbon society and green growth'. The government subsidies and Feed-in Tariff (FIT) increased domestic usage of solar power by supplying photovoltaic housing and photovoltaic generation systems. Since 2000, solar power industry has been the world's fastest growing source with the annual growth rate of 52.5%. Especially, BIPV(Building Integrated Photovoltaic) systems are capturing a growing portion of the renewable energy market due to several reasons. BIPV consists of photovoltaic cells and modules integrated into the building envelope such as a roof or facades. By avoiding the cost of conventional materials, the incremental cost of photovoltaics is reduced and its life-cycle cost is improved. When it comes to atypical building, numerous problems occur because PV modules are flat, stationary, and have its orientation determined by building surface. However, previous studies mainly focused on improving installations of solar PV technologies on ground and rooftop photovoltaic array and developing prediction model to estimate the amount of produced electricity. Consequently, this paper discusses the problem during a planning and design stage of BIPV systems and suggests the method to select optimal design of the systems by applying the national strategy and economic policies. Furthermore, the paper aims to develop BIM tool based on the engineering knowledge from experts in order for non-specialists to design photovoltaic generation systems easily.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권2호
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• pp.94-100
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• 2005

Korea Electrotechnology Research Institute(KERI) has successfully developed a 100hp-1800rpm-class high temperature superconducting(HTS) motor with high efficiency under partnership with Doosan Heavy Industries & Construction Co. Ltd. This motor has a HTS field winding and an air-cooled stator. The advantages of HTS motor can be represented by a reduction of 50% in both losses and size compared to conventional motors of the same rating. The cooling system is based on the heat transfer mechanism of the thermosyphon by using GM cryocooler as cooling source. The cold head is in contact with the condenser of a Ne-filled thermosyphon. Independently, the rotor assembly was tested at the stationary state and combined with stator. The HTS field winding could be cooled into below 30K. Test of open-circuit characteristics(OCC) and short-circuit characteristics(SCC) and load test with resistive load bank were conducted in generator mode. Also, load tests in motor mode driven by inverter were finished at KERI. Maximum operating current of field winding at 30K was 120A. From OCC and SCC test results synchronous inductance and synchronous reactance were 2.4mH, 0.49pu, respectively. Efficiency of this HTS machine was 93.3% in full load(100hp) test. This paper will present design, construction. and experimental test results of the 100hp HTS machine.

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.224-234
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• 2008

Multi-phase machines can be used in variable speed drives. Their applications include electric ship propulsion, 'more-electric aircraft' and traction applications, electric vehicles, and hybrid electric vehicles. Multi-phase machines enable independent control of a few numbers of machines that are connected in series in a particular manner with their supply being fed from a single voltage source inverter(VSI). The idea was first implemented for a five-phase series-connected two-motor drive system, but is now applicable to any number of phases more than or equal to five-phase. The number of series-connected machines is a function of the phase number of VSI. Theoretical and simulation studies have already been reported for number of multi-phase multi-motor drive configurations of series-connection type. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information concerning the rotor speed is extracted from measured stator currents and voltages at motor terminals. Open-loop estimators or closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. This paper analyses operation of an MRAS estimator based sensorless control of a vector controlled series-connected two-motor five-phase drive system with current control in the stationary reference frame. Results, obtained with fixed-voltage, fixed-frequency supply, and hysteresis current control are presented for various operating conditions on the basis of simulation results. The purpose of this paper is to report the first ever simulation results on a sensorless control of a five-phase two-motor series-connected drive system. The operating principle is given followed by a description of the sensorless technique.

• Mass Spectrometry Letters
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• 제9권1호
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• pp.30-36
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• 2018

A quantitation method for free amino acids in human serum was developed using a stepwise-dilution method and a bimodal cation exchange (CEX)/hydrophilic interaction liquid chromatography (HILIC)-tandem mass spectrometry system equipped with an electrospray ionization source (ESI/MS/MS). This method, which was validated using quality control samples, was optimized for enhanced selectivity and sensitivity. Dithiothreitol (DTT) was used as a reducing agent to prevent the oxidation of a serum sample ($50{\mu}L$), which was then subjected to stepwise dilution using 3, 30, and 90 volumes of acetonitrile containing 0.1% formic acid. Chromatographic separation was performed on an Imtakt Intrada Amino Acid column ($50mm{\times}3mm$, $3{\mu}m$) in mixed mode packed with CEX and HILIC ligands embedded in the stationary phase. Underivatized free amino acids were eluted and separated within 10 min. As a result of the validation, the precision and accuracy for the inter- and intraday assays were determined as 2.11-11.51% and 92.82-109.40%, respectively. The lowest limit of quantification (LLOQ) was $0.5-4.0{\mu}g/mL$ and the matrix effect was 80.22-115.93%. The proposed method was successfully applied to the quantitative analysis of free amino acids in human serum.