• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.121-126
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• 2015

The objective of this study is to evaluate the catalytic potential of the porous material prepared from water treatment sludge. The textural properties of the catalyst were studied using $N_2$ adsorption and desorption isotherms, scanning electron microscope, and X-ray diffraction. The pellet-type catalyst prepared using water treatment sludge is determined to be a material that contains mesopores as well as micropores. The specific surface area of the catalyst is $157m^2/g$. Acidic characteristics of the catalyst are analyzed by temperature-programmed desorption of ammonia and infrared spectroscopy of adsorbed pyridine. 2-Butanol dehydration reaction was carried out in a fixed bed catalytic reactor. Yields of 1-butene, trans-2-butene, and cis-2-butene at $350^{\circ}C$ were 25.6 wt%, 19.2 wt%, and 29.9 wt%, respectively. This catalytic activity of the catalyst based on water treatment sludge in 2-butanol dehydration is due to the acid sites composed of Bronsted acid sites and Lewis acid sites. It was confirmed that the catalyst based on water treatment sludge can be utilized to produce $C_4$ olefin through butanol dehydration.

• Korean Journal of Ichthyology
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• v.30 no.3
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• pp.131-136
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• 2018

Decrease in seawater temperature during winter is one of the most important and serious issues confronted by fish net-cage aquaculture farms. This can become the cause of the manifestation of diseases and ensuing mass mortality. The present study was conducted to assess the survival rate, the range of limited low-temperature, the response of oxidative stress in the blood of red sea bream Pagrus major with decrease of water temperature. Low-lethal temperature for 7 days of P. major ($7day-LT_{50}$) was $6.54^{\circ}C$ (confidence limit: $6.31{\sim}6.71^{\circ}C$). Oxygen consumption rate was decreased with lower temperature. It showed the minimum value at the range of low-lethal temperature. Osmolality at $5^{\circ}C$ and $6^{\circ}C$ experimental group was higher significantly than control group. SOD (superoxide dismutase) activity was increased significantly at $5^{\circ}C$ experimental group compared to control group. This study data will be used to determine the appropriate area for aquaculture of red sea bream. It also manage fish net-cage farm to cope with the mass mortality occurring frequently during winter season.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.559-567
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• 2008

SAPO-34 is a well-known catalyst for methanol to olefins (MTO) process, but is rapidly deactivated by coke formation. It is necessary to improve the catalyst lifetime of SAPO-34 for MTO process. In the present work, SAPO-34 catalysts were synthesized with a variety of structure directing agent, and the physicochemical properties of the catalysts were examined by $N_2$-isotherm, XRD, SEM, and $NH_3$-TPD. It was found that mixed structure directing agents, especially DEA and TEAOH, gave well developed SAPO-34 crystal structure and reduced the crystal size and moderated acidity of SAPO-34 under the same synthetic conditions as that of various structure directing agents. Also, we could find that SAPO-34 catalyst prepared by mixed templates of DEA and TEAOH had the superior catalytic activity and the longer lifetime in MTO reaction.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.640-645
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• 2000

The effect of gamma-irradiation on the quality changes of the grain shape improved Meju was studied. Meju was prepared, irradiated at 0, 5, 10 and 20 kGy, and then stored at $25^{\circ}C$ for six months. The results showed that the fungi and acid producing bacteria were completely eliminated by gamma-irradiation with dose of 10 kGy or higher and the Bacillus was decreased by 5 log cycles with dose of 10 kGy. The $D_{10}$ values of the fungi, Bacillus and acid producing bacteria were 0.79, 2.28 and 1.17 kGy, respectively. Also, the microorganisms that survived irradiation was decreased significantly with the duration of storage period. The $NH_3-nitrogen$, negative factors of quality of Meju, and browning were repressed and the protease activity and pH were not affected by gamma-irradiation. Therefore, it was considered that the Meju treated with gamma-irradiation maintained better quality than that of the control with storage.

• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.91-96
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• 2007

Lab scale experimental study was carried out for SBR process, to investigate the effects of influent ship sewage organic compound removal and Bacillus sp. state on design parameters. This process was able to remove nitrogen and phosphorus as well as organic matter efficiently. More than 95% of chemical oxygen demand(COD) were removed. In addition, about 97% of total nitrogen (T-N) was reduced. The total phosphorus(T-P) reduction averaged 93%. The performance load of SBR process was shown to be $0.095kg{\cdot}TOC/m^3{\cdot}day$. The pH was decreased from 8.1 to 7.0 within 30 min and increased to 7.3 at the end of anoxic stage, and these phenomena were explained. The sludge produced in the SBR process is characterized by low generation rate (about $0.36kg{\cdot}MLSS/kg{\cdot}TOC$) and excellent settleability. The number of Bacillus sp. in the SBR was 24.2%, indicating that Bacillus sp. was a predominant species in the reactor.

• Korean Journal of Microbiology
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• v.34 no.4
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• pp.200-206
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• 1998

The distributions and characteristics of bacteria on the deodorizing biofilters were studied as a part of biofiltration research for odor gas removal. The odor gas originated from a currently operating nightsoil treatment plant were mainly nitrogenous compounds of ammonia and amines. The filter media were consisted various ratio of pine bark, nightsoil cast and compost, and were sampled before and after operation of 153 days. Before operation, the level of bacteria on nitrification agar medium, nutrient agar medium and thiosulfate agar medium were around $10^7{\sim}10^8cfu/g$ media. After operation, the level decreased but still high as $10^5{\sim}10^7cfu/g$ media. The bacteria from reactors before and after operations were either rod or coccus after growth on nitrification agar media. The 45 isolated heterotrophic bacteria were further characterized and Pseudomonas, Bacillus, Flavobacterium, Alcaligenes were dominant genera. Genus Alcaligenes was particularly dominant when the isolates were incubated on nitrification agar media first and then transfered to nutrient media. The portion of Alcaligenes in the biofilter increased after operation, and was higher in the media contained nightsoil cast, which showed better treatment than the media with pine bark only.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.34-40
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• 2014

Mesoporous SAPO-34 catalyst was successfully synthesized by the hydrothermal method using carbon nanotube (CNT) as a secondary template. The effects of CNT contents (0.5, 1.5, 2.5, and 4.5 mol%) on catalytic performances were investigated. The synthesized catalysts were characterized with XRD, SEM, nitrogen physisorption isotherm and $NH_3$-TPD. Among the synthesized catalysts, SAPO-34 catalyst prepared by the addition of 1.5 mol% CNT (1.5C-SAPO-34) observed not only the largest amounts of mesopore volume but also acid sites. However, the mesopore volume was relatively decreased by further increasing of CNT contents due to the formation of small crystalline. The catalytic lifetime and the selectivity of light olefins ($C_2{\sim}C_4$) were examined for the dimethyl ether to olefins reaction. As a result, the 1.5C-SAPO-34 catalyst showed an improvement of ca. 36% in a catalytic lifetime and a better selectivity to light olefins as compared with the general SAPO-34 catalyst.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.611-619
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• 2019

This study was carried out to investigate fuel decomposition characteristics and coke formation according to types of endothermic fuels and methods of catalyst molding. Methylcyclohexane (MCH), n-dodecane, and exo-tetrahydrodipentadiene (exo-THDCP) were used as the endothermic fuels. As a catalyst, USY720 supported with platinum was used. It was manufactured by only using pressure to disk-type, or pelletized with a binder and a silica solution. The characteristics of the catalysts according to the molding method were analyzed by X-ray diffraction analysis, scanning electron microscopy, nitrogen adsorption-desorption isotherm, and ammonia temperature programmed desorption analysis. The reaction was carried out under conditions of high temperature and high pressure ($500^{\circ}C$, 50 bar) in which the fuel could exist in a supercritical state. The product was analyzed by gas chromatograph/mass spectrometer and the coke produced by the catalyst was analyzed by thermogravimetric analyzer. After the reaction, the composition of the products varied greatly depending on the structure of the fuel. In addition, the crystallinity and surface properties of the catalysts were not changed by the method of catalyst molding, but the changes of the acid sites and the pore characteristics were observed, which resulted in changes in the amount and composition of products and coke.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.271-278
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• 2021

Azolla is a genus of small aquatic ferns native to Asia, Africa, and America. Azolla is potentially significant as a nitrogen source in agriculture, particularly in conjunction with rice (Oryza sativa L.) cultivation. In addition, Azolla may either control weeds or act as a weed depending on management; therefore, we aimed to determine the effect of Azolla incorporation on weed (e.g., Monochoria vaginalis, Rotala indica, Aeschynomene indica, and Cyperus amuricus) control and its other benefits during rice cultivation. The effects of Azolla on weed emergence were evaluated based on plot area coverage by the Azolla mat, which appears as a green sheet over water, and the rate of weed emergence in paddy field. Weed occurrence was investigated 40 days after Azolla inoculation. Soil samples from the experimental plots were collected following harvest in 2014-2015, and analyzed. Moreover, rice growth, yield, and grain quality were measured. Azolla suppressed weed growth by 72%. Azolla mat incorporation in rice fields suppressed weed growth by over 60%. In addition, Azolla promoted nitrogen fixation. Compared with nitrogen management using chemical fertilizers, Azolla incorporation showed the potential for various positive effects, including the improvement of soil fertility by increasing total nitrogen, and organic matter content. Rice grown with Azolla maintained its yield without additional herbicide treatment. Moreover, the palatability of cooked rice was better when grown with Azolla.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.3
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• pp.115-123
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• 2010

The occurrence and variation of oxygen deficient water mass (ODW) in Namdae stream estuary, Yangyang were studied. Field observations for water properties and sediment environments were conducted at 5 stations of the estuary from April 2008 to November 2008. The coastal sandbar is developed at the estuary mouth, and there is a pool between the estuary mouth and about 2.3 km upstream of the estuary. The pool is relatively deep and narrow compared to riverbed of the estuary. The ODW was observed continuously in the pool from May to October. The ODW extends vertically up to 2 m depth in August, and maximum length of the ODW were about 2.3 km. Mean concentration of ignition loss (IL) and acid volatile sulfide (AVS) of sediment was 7.5~9.0%, $0.282{\sim}1.106\;mg/g{\cdot}dry$ wt, respectively. Ammonium concentration in the bottom layer during formation period of the halocline and the ODW was 4~23 times higher than that of surface layer. ODW was initiated by the introduction of seawater into bottom of the estuary pool to make a strong halocline, and then decomposition of organic matter within sediment accelerated the formation of the ODW.