• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.232-232
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• 2009

최근 WGS반응용 Pt 촉매의 성능 향상을 위한 다양한 담체 및 조촉매(Promotor) 개발에 대한 연구가 활발하게 진행되고 있다. 선행 연구결과, 입방(Cubic)구조를 가지는 $Ce_{0.8}Zr_{0.2}O_2$ 담체는 정방 입계(Tetragonal)구조를 가지는 $Ce_{0.2}Zr_{0.8}O_2$ 담체 또는 혼합산화물(Mixed oxide)구조를 가지는 $Ce_{0.5}Zr_{0.5}O_2$ 담체 보다 높은 활성과 안전성을 가진다. 이것은 촉매의 성능 향상이 Ce-$ZrO_2$의 결정구조에 의존한다는 것을 나타낸다. 따라서 WGS 반응에서 Ce/Zr 비에 따라 변화된 담체 특성이 Pt 촉매의 활성에 영향이 있을 것으로 예상되며 실험결과 1% Pt/$CeO_2$ 촉매가 가장 높은 활성을 나타내었다. 따라서 Pt/Ce-$ZrO_2$ 촉매의 성능 향상을 위해 Ce-$ZrO_2$ 담체에 조촉매인 Ni을 첨가하여 촉매적 활성을 비교하여 보았다. 촉매는 2%의 Pt과 15%의 Ni로 고정하였고 Ce/Zr 비를 제조변수로 하였다. 제조된 모든 담체는 공침법(Co-precipitation)을 사용하여 제조하였으며 $500^{\circ}C$에서 6시간 소성하였다. Pt 촉매는 함침법 (Incipient wetness impregnation)으로 담지 시켰다. 2% Pt/Ce-$ZrO_2$ 촉매와 2% Pt/15% Ni-Ce-$ZrO_2$ 촉매는 저온영역($200^{\circ}{\sim}320^{\circ}C$)에서 비슷한 CO 전환율을 나타내었으나 고온영역($360^{\circ}C{\sim}400^{\circ}C$)에서는 2% Pt/15% Ni-Ce-$ZrO_2$ 촉매가 더 높은 CO의 전환율을 나타내었다. 이것은 Ni의 영향으로 고온에서 부반응인 메탄화 반응(Methanation reaction)이 생긴 것으로 판단되어 메탄($CH_4$)의 선택도를 살펴본 결과 2% Pt/15% Ni-Ce-$ZrO_2$ 촉매가 고온영역($360^{\circ}{\sim}400^{\circ}C$)에서 급격하게 증가하는 것으로 나타나 메탄화 반응이 일어난 사실을 증명한다.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.149-154
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• 2012

The adsorption and desorption behavior of biofilter-medium was investigated on the performance of an adsorption column. Continuous flow-isothermal adsorption experiments were performed to treat waste air containing such a VOC as ethanol under the same condition of > 90% relative humidity as the condition of the feed to a biofilter process. In case of feeding waste air containing ethanol of 1,000 ppmv (or 2,050 mg ethanol/$m^3$) to the adsorption system at the rate of 2 L/min, the onsets of its breakthrough and reaching the state of dynamic equilibrium at the exit had been delayed 10 and 3 times, respectively, later than those at the 1st stage sampling port. Moreover, in case of 2,000 ppmv (or 4,100 mg ethanol/$m^3$), they had been delayed 9 and 3 times, respectively. Thus, regardless of feeding concentration, the ratios of delaying period were observed to be quite consistent each other at the exit of the adsorption column. With regard to the period of desorption, the ratios of delaying period were consistent each other to be 1.5 for both cases. In addition, the effect of microbial activity and sterilization-process was studied on adsorption equilibrium. The ethanol concentration in the vapor phase of vials packed with sterilized granular activated carbon (GAC) was quite consistent to that with unsterilized GAC. However, the ethanol concentrations in the vapor phase of vials packed with unsterilized compost and the unsterilized mixture of GAC and compost were higher than those with sterilized compost and the sterilized mixture of GAC and compost, respectively.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.270-276
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• 2008

$N_2$ doped $TiO_2$ nano-sized powder was prepared using a DC arc plasma jet and investigated with XRD, BET, SEM, TEM, and photo-catalytic decomposition. Recently the research interest about the nano-sized $TiO_2$ powder has been increased to improve its photo-catalytic activity for the removal of environmental pollutants. Nitrogen gas, reacting gas, and titanium tetrachloride ($TiCl_4$) were used as the raw materials and injected into the plasma reactor to synthesize the $N_2$ doped $TiO_2$ power. The particle size and XRD peaks of the synthesized powder were analyzed as a function of the flow rate of the nitrogen gas. Also, the characteristics of the photo-catalytic decomposition using the prepared powder were studied. For comparing the photo-catalytic decomposition performance of $TiO_2$ powder with that of $TiO_2$ coating, $TiO_2$ thin films were prepared by the spin coating and the pulsed laser deposition. For the results of the acetaldehyde decomposition, the photo-catalytic activity of $TiO_{2-x}N_x$ powder was higher than that of the pure $TiO_2$ powder in the visible light region. For the methylene blue decomposition, the decomposition efficiency of $TiO_2$ powder was also higher than that of $TiO_2$ film.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.807-813
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• 2014

The Ag-impregnated activated carbon was produced from bamboo activated carbon by soaking method of silver nitrate solution. The carbonization and activation of raw material was conducted at $900^{\circ}C$. Soaking conditions are the variation of silver nitrate solution concentration (0.002~0.1 mol/L) and soaking time (maximum 24 h). The specific surface area and pore size distribution of the prepared activated carbons were measured. Also, NO and activated carbon reaction were conducted in a thermogravimetric analyzer in order to use for de-NOx agents of used activated carbon. Carbon-NO reactions were carried out with respect to reaction temperature ($20{\sim}850^{\circ}C$) and NO gas partial pressure (0.1~1.8 kPa). As results, Ag amounts are saturated within 2h, Ag amounts increased 1.95 mg Ag/g (0.2%)~ 88.70 mg Ag/g (8.87%) with the concentration of silver nitrate solution in the range of 0.002~0.1 mol/L. The specific volume and surface area of bamboo activated carbon of impregnated with 0.2% silver were maximum, but decreased with increasing Ag amounts of activated carbon due to pore blocking. In NO reaction, the reaction rate of impregnated bamboo activated carbon was retarded as compare with that of bamboo activated carbon. Measured reaction orders of NO concentration and activation energy were 0.63[BA], 0.69l[BA(Ag)] and 80.5 kJ/mol[BA], 66.4 kJ/mol[BA(Ag)], respectively.

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.154-159
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• 2004

Bacillus species were isolated from swine manure to develope the microbial additive suitable for the rapid com-posting. The 3 of 4 isolated strains were identified as Bacillus cereus KD-2, B. pumilus KD-3, and B. licheni-formis KD-4. Bacillus sp. KD-1 was, however, not highly identical with any Bacillus sp. The isolated strains were analyzed their growth rates, enzyme activities, and antibacterial activities. The maximum growth tem-peratures of KD-1, KD-2, KD-3 and KD-4 were $45^{\circ}C$, $50^{\circ}C$, $53^{\circ}C$, and $55^{\circ}C$, respectively. The activities of pro-tease or amylase in mixed culture of 4 strains were similar in the range of $37^{\circ}C$ to $53^{\circ}C$ and activities of lipase in the range of $37^{\circ}C$ to $42^{\circ}C$ were twice higher than those of lipase in the range of $47^{\circ}C$ to $53^{\circ}C$. The antibacterial activity of KD-l, KD-2, or KD-3 against each other was not detected. That of KD-4 against KD-1, KD-2, or KD-3 was, however, detected. The organic compound and C/N ratio of compost fermented by the mixed culture were determined as 61.9% and 22.4%, respectively. The concentration of the ammonia gas was 12.35 mg/l in the liquid compost.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.171-178
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• 2007

This study was carried out to investigate the effect of microbial complex diets on improvement of air quality in finishing pig building. Ammonia and hydrogen sulfide concentrations were significantly(p<0.05) decreased by dietary supplementation of 0.1% level of microbial complex compared with those of control according to the time in the finishing pig building. Characteristics of piggery liquid slurry that total nitrogen and $NH_3-N$ of treatment were reduced relatively compared with those of control, and were decreased depending on the time. In conclusion, the result obtained from this study suggest that the dietary supplementation of microbial complex for finishing pigs may improve environment in the finishing pig building.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.185.2-186
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• 2003

세계적으로 최소가공식품(minimally processed foods)의 시장이 확대되면서, 최소가공된 과채류의 미생물학적 안전성 확보가 중요한 사안으로 대두되고 있다. 이에 본 연구는 김치제조용 원료배추를 모델로 하여 감마선 및 가스치환 포장법을 병용한 절임배추의 미생물학적, 이화학적 특성을 평가하였다. Fresh-cut상태의 절임배추(염농도 3%)를 각각 air, 100% $CO_2$, 25% $CO_2$/75% $N_2$가스를 주입하여 포장한 후 0, 0.5, 1, 2 kGy의 선량으로 감마선 조사하여 3주 동안 저장하면서 분석에 사용하였다. Total aerobic bacteria, coliforms, Salmonella, lactic acid bacteria의 분포를 살펴본 결과, $CO_2$혹은 $CO_2$/$N_2$포장과 감마선을 병용처리한 경우 저장기간 동안 total aerobic bacteria, coliforms 및 Salmonella 모두 1kGy의 선량에서 90% 이상 감소시킬 수 있는 것으로 나타나, 일반 함기포장보다 효과적인 것으로 나타났다. 색도 및 물성은 포장방법에 따른 차이를 보이지 않았으며, pH의 경우도 감마선 조사 및 가스치환 포장시 더욱 효과적으로 유지할 수 있었다. FRAP(ferric reducing antioxidant power) value 및 DPPH radical 소거능과 같은 생리활성 능력을 측정한 결과 포장방법 및 감마선 조사에 의한 차이를 보이지 않았다. 따라서 가스치환 포장 및 감마선 조사를 병용시 함기포장구 보다 낮은 감마선 조사선 량에서 병원성 미생물을 제어할 수 있었으며, 이화학적 품질이 우수하고 저장성이 향상된 절임배추를 제조할 수 있었다.7로 4$0^{\circ}C$ 진공건조와 -7$0^{\circ}C$ 동결건조의 L값 변화보다 큰 변화를 보였고, 또한‘a’값과 ‘b’값의 경우도 마찬가지로 5$0^{\circ}C$ 열풍건조의 경우가 양파의 내부와 외부면의 적색도 및 황색도 변화가 크게 일어나는 경향을 나타내었다. 건조과정 중 vitamin C의 함량변화는 건조에 의한 수분함량의 감소로 vitamin C의 함량은 상대적으로 증가하였고, -7$0^{\circ}C$ 동결건조의 경우가 가장 높은 vitamin C의 증가량을 나타내었고, 그와 반대로 5$0^{\circ}C$ 열풍건조의 경우는 열에 의한 vitamin C의 변화로 인한 상대적 증가량은 감소하는 경향을 나타내었다.아현미가 더욱 조밀하였다. 10시간 탈삽처리에서 상품성이 우수하였다. 그러나 25'E 28시간 탈삽처리는 탈삽의 균일도가 다른 처리에 비해 떨어지는 경향이었다. 경우, 사과표피의 색도 변화를 현저히 지연시킴을 확인하였다. 또한 control과 비교하여 성공적으로 사과에 코팅하였으며, 상온에서 보관하여을 때 사과의 품질을 30일 이상 연장하는 효과를 관찰하였다. 이들 결과로부터 대두단백질 필름이 과일 등의 포장제로서 이용할 가능성을 확인하였다.로 [-wh] 겹의문사는 복수 의미를 지닐 수 없 다. 그러면 단수 의미는 어떻게 생성되는가\ulcorner 본 논문에서는 표면적 형태에도 불구하고 [-wh]의미의 겹의문사는 병렬적 관계의 합성어가 아니라 내부구조를 지니지 않은 단순한 단어(minimal $X^{0}$ elements)로 가정한다. 즉, [+wh] 의미의 겹의문사는 동일한 구성요 소를 지닌 병렬적 합성어([$[W1]_{XO-}$ $[W

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.51-59
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• 2001

Column and box tests were performed to investigate the removal efficiency of NAPL using the surfactant enhanced flushing In heterogeneous medium. Homogeneous Ottawa sand and heterogeneous soil were used to verify the increase of remediation efficiency for the surfactant enhanced flushing in column test. Box tests with two different heterogeneous sub-structure were performed to quantify the capability of the surfactant enhanced flushing as a remediation method to remove NAPL from the heterogeneous medium. Two different grain size sand layers were repeated in the box to simulate the heterogeneous layer formation and the modified fault structure was built to simulate the fault system in the box. O-xylene as a LNAPL and PCE as a DNAPL were used and oleamide as a non-ionic surfactant. The maximum NAPL effluent concentration with 1% oleamide flushing in the homogeneous column test increased about 460 times compared to that with only water flushing and about 250 times increased in the real soil column test. In heterogeneous medium, the maximum effluent concentration increased about 150 times in 1% oleamide flushing and most of NAPL were removed from the box within 8 pore volume flushing, suggesting that the removal efficiency increased very much compared to in only water flushing. Results investigated the capability of the surfactant enhanced remediation method to remove NAPL even in heterogeneous medium.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.356-362
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• 2006

The $SO_2$ reduction using CO and $H_2$ over Sn-Zr based catalysts was performed in this study. Sn-Zr based catalysts with Sn/Zr molar ratio (0/1, 1/4, 1/1, 2/1, 3/1, 1/0) were prepared by the precipitation and co-precipitation method. The effect of the temperature on the reaction characteristics of the $SO_2$ reduction with a reducing agent such as $H_2$ and CO was investigated under the conditions of space velocity of $10,000ml/g_{-cat.}h$, $([CO(or\;H_2)]/[SO_2])$ of 2.0. As a result, the activity of Sn-Zr based catalysts were higher than $SnO_2$ and $ZrO_2$. The reactivity for the $SO_2$ reduction with CO was higher than that with $H_2$, and sulfur yield in the $SO_2$ reduction by $H_2$ was higher than that by CO. The reactivity for the $SO_2$ reduction with $H_2$ was increased with the reaction temperature regardless of Sn-Zr based catalyst with a Sn/Zr molar ratio. $SnO_2-ZrO_2$ (Sn/Zr=1/4) had highest activity at $550^{\circ}C$, in the $SO_2$ reduction with $H_2$ and $SO_2$ conversion of 94.4％ and sulfur yield of 66.4％ were obtained at $550^{\circ}C$. On the other hand, in the $SO_2$ reduction by CO, the reactivity was decreased with the increase over $325^{\circ}C$. At the optimal temperature of $325^{\circ}C$, $SO_2$ conversion and sulfur yield were about 100％ and 99.5％, respectively, in the $SO_2$ reduction over $SnO_2-ZrO_2$ (Sn/Zr=3/1). Also, the $SO_2$ reduction using syngas with $CO/H_2$ ratio over $SnO_2-ZrO_2$ (Sn/Zr=2/1) was performed in order to investigate the application possibility of the simulated coal gas as the reductant in DSRP. As a result, the reactivity of the $SO_2$ reduction using syngas with $CO/H_2$ ratio was increased with increasing the CO content of syngas. Therefore, it could be known that DSRP using the simulated coal gas over Sn-Zr based catalyst is possible to be realized in IGCC system

• Journal of Life Science
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• v.17 no.12
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• pp.1660-1668
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• 2007

The non-ionic surfactant (NIS) Tween 80 was evaluated for its ability to influence invitro cumulative gas production, dry matter digestibility, cellulolytic enzyme activities, anaerobic microbial growth rates, and adhesion to substrates by mixed rumen microorganisms on rice straw, alfalfa hay, cellulose filter paper and tall fescue hay. The addition of NIS Tween 80 at a level of 0.05% increased significantly (P<0.05) in vitro DM digestibility, cumulative gas production, microbial growth rate and cellulolytic enzyme activity from all of substrates used in this study. In vitro cumulative gas production from the NIS-treated substrates; rice straw, alfalfa hay, filter paper and tall fescue hay was significantly (P<0.05) improved by 274.8, 235.2, 231.1 and 719.5% compared with the control, when substrates were incubated for 48 hr in vitro. The addition of 0.05% NIS Tween 80 to cultures growing on alfalfa hay resulted in a significant increase in CMCase (38.1%), xylanase (121.4%), Avicelase (not changed) and amylase (38.2%) activities after 36 h incubation. These results indicated that the addition of 0.05% Tween 80 could greatly stimulate the release of some kinds of cellulolytic enzymes without decreasing cell growth rate in contrast to trends reported with aerobic microorganism. Our SEM observation showed that NIS Tween. 80 did not influence the microbial adhesion to substrates used in the study. Present data clearly show that improved gas production, DM digestibility and cellulolytic enzyme activity by Tween 80 is not due to increased bacterial adhesion on the substrates.