• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.410-415
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• 2009

A hydrogen cooling method is used in a power generator for removing the unnecessary heat due to the windage loss of a rotor and the joule heat of a stator. A MEA (Membrane Electrolyte Assembly) hydrogen generator has been developed and applied as a hydrogen supplying system for the cooling of a 350MW power generator. As a field application result, the average potential of eleven cells and the voltage efficiency were measured 2.26V/cell and 65.4% (Higher Heating Value) respectively at the hydrogen pressure of 6 Bar, the hydrogen flow rate of 9.1L/min, and the current of 150A.

• Journal of Advanced Marine Engineering and Technology
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• 제32권1호
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• pp.27-32
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• 2008

Recently, we have a lot of interest in alternative fuels to provide energy independence from oil producing country and to reduce exhaust emissions for air pollution prevention. Biodiesel, which can be generated from natural renewable sources such as new or used vegetable oils or animal fats, may be used as fuel in diesel engine of compression ignition engine. In this paper, the test results on specific fuel consumption and exhaust emissions of neat diesel oil and biodiesel blends(10 vol.% biodiesel and 20 vol.% biodiesel) were presented using four stroke, direct injection diesel engine, especially this biodisel was produced from soybean oil at our laboratory. This study showed that Soot and CO emission were decreased as the blending ratios of biodiesel to diesel oil increased, on the other hand NOx emission was slightly increased because of the oxygen content in biodiesel. Also, the biodiesel blends yielded slightly higher specific fuel consumption than that of diesel oil because of lower heating value of biodiesel.

• 환경위생공학
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• 제15권4호
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• pp.78-83
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• 2000

The emission factor of nitrogen oxides(NOx) was evaluate to clarify the characteristics of NOx emitted from seven large combustion facilities in seoul area. The emission factors of NOx at A-1 and A-2 facilities of internal combustion engine were 66.957kgNOx/ton and 20.913kgNOx/ton, respectively. The emission factor of A-1 facility was higher than that of A-2 facility even same internal combustion engine, because A-1 facility adopted SCR(selective catalystic reactor) for reduction of NOx emission factor of A-2, A-4, and A-7 power generation boiler facilities were 4.300kgNOx/ton, 2.460kgNOx/ton and 1.796kgNOx/ton, respectively. The capacity of A-2 facility was about two times than that of A-4 and A-7. These emission factors were lower than those at facilities in other areas of korea, because of using low NOx burner of power generation boiler. The emission factors of NOx at A-3 and A-6 incinerator facilities were 0.147kgNOx/ton and 0.221kgNOx/ton which were lower than other facilities, respectively, because these facilities incinerate municipal solid waste of low heating value and uwe SCR for reducing NOx concentration.

• 한국분무공학회지
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• 제15권1호
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• pp.31-37
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• 2010

The aim of this work is to investigate the spray and combustion characteristics of dimethyl-ether (DME) at various injection conditions. The spray characteristics such as spray tip penetration and spray cone angle were experimentally studied from the spray images which obtained from the spray visualization system. Combustion and emissions characteristics were numerically investigated by using KIVA-3V code coupled with Chemkin chemistry solver. From these results, it revealed that DME spray had a shorter spray tip penetration and wider spray cone angle than that of diesel spray due to the low density, low surface tension, and fast evaporation characteristics. At the constant heating value condition, DME fuel showed higher peak combustion pressure and earlier ignition timing, because of high cetane number and superior evaporation characteristics. In addition, the combustion of DME exhausted more $NO_x$ emission and lower HC emission due to the active combustion reaction in the combustion chamber. The result shows that DME had a little soot emission due to its molecular structure characteristics with no direct connection between carbons.

• 대한가정학회지
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• 제4권1호
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• pp.589-594
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• 1963

Ascorbic acid has a strong power to reduce other materials, so by using this reducing power we can analise many materials quantitatively. Dihydro-ascorbic acid is quantitatively changed into ascorbic acid under a certain condition, if reduced by hydrogen-sulfide. Dihydro-ascorbic acid also has physiolosical effect, but less effect than ascorbic acid. The effect of dihydro-ascorbic acid is regarded as a half of that of ascorbic acid. Among the analytical methods applying this theory the method using 2.6 dichlorophenol indophenol what called the method of Indophenol is used most widely; so does Hydrazine-method. But comparing these two methods the former shows a little higher rate in analytical value. Vegetable are vital sources for vitamin C. According to the report of the commitee of FAO Korean branch the amount of daily per head average intake of vitamin C is about 70mg in raw materials. Since vitamin C is easily affected by heating or oxidation in Cooking the loss is not a little. Consequntly it is regarded that the actual amount of intake will be much less than basic amount. It is therefore very important to find out that how much percent of the loss there will be in case of cooking, in order to dicide the actual amount of in take as proper nutrition for a person. Therefore this paper intended to give some help in setting a standard amount of V.C intake, by measuring the change of the V.C amount using the general cooking method and by measuring amount of V.C contained in the part of vegetable, used in Korea abundantly.

• Journal of Applied Biological Chemistry
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• 제42권4호
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• pp.175-179
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• 1999

Grape seed oil was extracted using different preparatory treatments as follows: (1) grinding, (2) grinding and roasting, (3) grinding and wet- roasting, (4) grinding, roasting, and wet-roasting, and (5) grinding, wet-roasting, and wet-roasting. The highest antioxidant activity was obtained from the sample with the method (2). Initial states of oxidation were similar except method (1) that showed more oxidized state, being P.O.V.8. Acid values were observed in the range from 1.42 to 1.89. The lowest acid value was found as 1.42 in method (1) and those of others were somewhat higher, indicating that heating process of roasting produced some free fatty acids. From the results of sensory evaluation, the best odor and taste were obtained from the methods (2) and (3). Repetitive procedure of wet-roasting, like method 5, caused some loss of flavor components and decrease in the sensory evaluation score. Addition of grape seed oil (method 2) to soybean and perilla oil at the level of 20% retained considerable antioxidant activities as much as 4.3 and 5 times, respectively, than 100% soybean or perilla oil stored for 12 weeks. When soybean or perilla oil was mixed with 20% grape seed oils, P.O.V. decreased to half of that of unmixed oils.

• 대한의용생체공학회:의공학회지
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• 제30권3호
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• pp.199-204
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• 2009

Iridium oxide films (IROFs) have been extensively studied as a material for electrical stimulation of neurons, as iridium oxide has higher charge storage capacity than other metal films. More recently, sputtered iridium oxide film (SIROF) has been studied, because it can be made more conveniently than activated iridium oxide film (AIROF). Typically, the SIROFs are grown at temperatures from 400 to 600 $^{\circ}C$. However, such high temperatures cannot be used when the iridium oxide (IrOx) film is to be deposited on a flexible polymer material, such as polyimide. In this paper, we show that we can still obtain excellent characteristics in SIROFs grown without heating (cold SIROF), by optimizing the growth conditions. We show that the oxygen flow rate is a critical parameter for controlling the surface properties of a cold SIROF. At an oxygen flow rate of 12 seem, the cold SIROF exhibited a charge storage capacity (CSC) of 60 mC/cm$^2$, which is comparable to or better than other published values for iridium oxide films including heated SIROFs. The film produced under these conditions also had the minimum impedance value of all cold SIROFs deposited for this study. A stability test and biocompatibility test also demonstrated the superiority of the optimized cold SIROF.

• 천문학회보
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• 제39권1호
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• pp.75.1-75.1
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• 2014

Sunspot penumbrae show supersonic downflow patches along the periphery. These patches are believed to be the return channels of the Evershed flow. There was previous study to investigate their structure in detail using Hinode SOT/SP observations (M. van Noort et al. 2013) but their data sample was only two sunspots. To make general description it needs to check more sunspot sample. We selected 242 downflow patches of 17 sunspots using Hinode SOT/SP observations from 2006 to 2012. Height-dependent maps of atmospheric parameters of these downflows was produced by using HeLix which was height dependent LTE inversion code of Stokes profiles. The inversion code at high resolution allows for the accurate determination of small scale structures. The recovered atmospheric structure of three layers indicates that regions with very high downflow velocities contain very strong magnetic fields reaching up to 7kG. The higher downflow velocity patches have bigger patch size. Magnetic fields of downflow patches are more vertical while penumbra shows horizontal field and neighbor of downflow patches have opposite polarity. Temperature of downflow patches at highest layer have more strong value than penumbra at deepest layer. The direction of velocity of downflow patches at highest layer have two branches. These result shows that we can expect some heating precess in the middle of layer.

• Fibers and Polymers
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• 제5권4호
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• pp.289-296
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• 2004

The kinetic parameters, including the activation energy E, the reaction order n, and the pre-exponential factor Z, of the degradation of the copolymers based on the poly(L-lactide) (PLLA) or poly(p-dioxanone-co-L-lactide) (PDO/PLLA) and diol-terminated poly(ethylene glycol) (PEG) segments have been evaluated by the single heating methods of Friedman and Freeman-Carroll. The experimental results showed that copolymers exhibited two degradation steps under nitrogen that can be ascribed to PLLA or PDO/PLLA and PEG segments, respectively. However, copolymers exhibited almost single degradation step in air. Although the values of initial decomposition temperature were scattered, copolymers showed the lower maximum weight loss rate and degradation-activation energy in air than in nitrogen whereas the higher value of temperature at the maximum rate of weight loss was observed in air.

• 한국진공학회지
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• 제12권4호
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• pp.228-234
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• 2003

전자빔으로 증발시킨 gadolinium(Gd) 원자증기의 속도를 미량 저울(microbalance)을 사용하여 측정하였다. 증발 표면의 온도가 2400-2500 K인 조건에서 약 900 ㎧의 속도가 측정되었다. 이 값은 단열팽창을 하는 이상적 단원자의 최대 속도에 비해 약 100 ㎧ 더 빠른 속도에 해당된다. 이 특이 현상의 원인을 고온에서 여러 개의 들뜬 에너지 준위에 분포한 Gd 원자의 내부 에너지가 단열팽창 중에 운동 에너지로 전환되는 것으로 설명하였다. 100개의 들뜬 에너지 준위를 원자증기의 엔탈피에 포함시켜 속도를 계산한 값이 실험 결과와 비교적 일치함을 보였다. 가열된 표면 온도의 변화에 따른 원자증기의 유동 특성에 대해서도 보고한다.