• Korean Journal of Soil Science and Fertilizer
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• v.17 no.3
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• pp.242-252
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• 1984

A port experiment was conducted to compare the effect of chemical forms of nitrogen fertilizers on the rice growth and soil characteristics. The nitrogen fertilizers used for this study were ammonium sulfate, ammonium nitrate, ammonium chloride and urea. The results are summarized as follows. 1. The differences in pH of the soil and surface water between treatments during the first week after fertilizer application were great and the pH values were in the order of urea > ammonium nitrate > ammonium sulfate > ammonium chloride treatment. However the differences were insignificant after the first week. 2. The differences in pH of the air-dried soil somewhat increased and pH values were in the order of urea > ammonium nitrate > ammonium chloride > ammonium sulfate treatment. 3. Sulfur contents of the soil and the rice leaf and N content of the rice leaf were highest when ammonium sulfate was applied. But there were few differences between the treatments in total N content of the soil and in P, K, Ca and Mg contents of the soil and the rice leaf. 4. Number of tillers and dry matter weight of the rice plant were highest in ammonium sulfate plot throughout all the growing stages. 5. Number of panicle per hill was highest in ammonium sulfate plot, and this brought the highest grain yield in ammonium sulfate plot. The lowest grain yield in ammonium nitrate plot resulted from the lowest number of panicle per hill and ripened grain ratio.

• Applied Biological Chemistry
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• v.48 no.2
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• pp.132-139
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• 2005

The major obstacle in the popularization of Chungkookjang is the short shelf-life of $2{\sim}3$ months and some problems concerning storage including the growth of molds even in the products even within shelf-life. To solve these problems we conducted a research to improve its storage by using the vacuumed packaging and sanitary method through seed culture, innoculation and sterilization. For the optimization of storage time, temperature and sterilization temperature, we measured viable cell numbers of bacteria and fungi, amount of gas outbreak and contents of amino type nitrogen and monitored these experimental results by response surface methodology of SAS program, so that we could observe the quality changes of Chungkookjang during shelf-life. Especially fungi, which are the biggest troublemaker in Chungkookjang shelf-life, couldn't be detected from the generally and vacuum-packed samples; also, viable cell numbers were highly influenced by sterilization temperature and in vacuum-packed samples. In the case of vacuum-packed samples, amount of gas outbreak was highly influenced by sterilization temperature of its storage conditions and it was higher in generally packed samples as compared to vacuum-packed samples even at any storage conditions. The changes of pH in generally and vacuum-packed samples were highly influenced by the storage temperature. As the temperatures of storage and sterilization were higher and the storage time was longer, so the amount of gas outbreak was accordingly lower. These results showed that amino type nitrogen contents in generally and vacuum-packed samples were systematically influenced by the temperature, storage time and sterilization temperature. Also the result showed that the change of amino type nitrogen contents during storage was less in vacuum-packed samples than in general ones. Based on the above results, we can produce Chungkookjang products with extended shelf-life of as far as 6 months without any quality change using sanitary manufacturing method, vacuumed packaging condition, sterilization in $70^{\circ}C$ for 60 minutes and storage under $10^{\circ}C$ during shelf-life. According to this research, we have the possibility to greatly increase the goods value of Chungkookjang by developing the manufacture processing and packaging.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.104-110
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• 2015

It is known that polymer concretes are 8~10 times more expensive than ordinary Portland cement concretes; therefore, in the production of polymer concrete products, it is very important to reduce the amount of polymer binders used because this occupies the most of the production cost of polymer concretes. In order to develop a technology for the reduction of polymer binders, smooth and spherical aggregates were prepared by the atomizing technology using the oxidation process steel slag (electric arc furnace slag, EAFS) and the reduction process steel slag (ladle furnace slag, LFS) generated by steel industries. A reduction in the amount of polymer binders used was expected because of an improvement in the workability of polymer concretes as a result of the ball-bearing effect and maximum filling effect in case the polymer concrete was prepared using the smooth and spherical atomized steel slag instead of the calcium carbonate (filler) and river sand (fine aggregate) that were generally used in polymer concretes. To investigate physical properties of the polymer concrete, specimens of the polymer concrete were prepared with various proportions of polymer binder and replacement ratios of the atomized reduction process steel slag. The results showed that the compressive strengths of the specimens increased gradually along with the higher replacement ratios of the atomized steel slag, but the flexural strength showed a different maximum strength depending on the addition ratio of polymer binders. In the hot water resistance test, the compressive strength, flexural strength, bulk density, and average pore diameter decreased; but the total pore volume and porosity increased. It was found that the polymer concrete developed in this study was able to have a 19% reduction in the amount of polymer binders compared with that of the conventional product because of the remarkable improvement in the workability of polymer concretes using the spherical atomized oxidation steel slag and atomized reduction steel slag instead of the calcium carbonate and river sand.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.1
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• pp.11-17
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• 2003

pH value of sampled fogwater at source regions (above highway and road) in Yongin sites showed the lowest value and was increased after passing the forest stands. Changes of ion concentrations through the forest stands showed a lowering tendency at sampling sites. The fogwater passing the forest stands (Quercus mangolica and Pinus rigida) surrendered acid pollutants to crown and stem from the atmosphere. It was concluded that environmental moisture in the atmosphere is acidified in fogwater. The influence was extended to the pure zone, and the frequency of acid rain has increased. The forests are assumed to remove air pollutants because ion concentrations in fogwater decreased after passing the forests. The fogwater which functions as a local sink for pollutants (H$_2$SO$_4$, HNO$_3$, etc.) falling on plant surfaces is considered to effectively remove acid pollutants. But if the deposition of pollutants exceeds the capacity of purification, it would damage the forest ecosystem. Further investigation is necessary to identify tree species tolerant to acid pollutants.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.414-419
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• 2005

This study was performed to compare the treatment efficiencies of two media, newly developed Bio-rock and conventional gravel, in soil clothing contact oxidation process. The composition of synthetic wastewater were $COD_{Cr}$ $150{\sim}370\;mg/L$, $BOD_5$ $150{\sim}270\;mg/L$, T-N $20{\sim}60\;mg/L$, T-P $5{\sim}25\;mg/L$, pH 7 and 2 mL/L of trace element solution. The experiment using two reactors was comparatively conducted for the flow rate of 40 L/d for 13 months, respectively. Initially Bio-rock reactor was increased to pH 12 due to $Ca(OH)_2$ with hydration of cement, but gravel reactor was dropped to pH 4 due to the degradation of organic material and nitrification. This significant pH variation deteriorated the growth and activity of microorganism. But the high pH of Bio-rock seems favorite to ammonia stripping and precipitation of phosphate. Such pH variation of Bio-rock and gravel reactors were finally stabilized to pH 8 and pH 6, respectively. The removal efficiencies of organic compounds from Bio-rock reactor were 96% of $COD_{Cr}$, 98% of $BOD_5$, 80% of T-N and 85% of T-P which stably coping against variation of influent concentration. But those of gravel reactor were 96% of $COD_{Cr}$, 96% of $BOD_5$, 42% of T-N and 40% of T-P, respectively. The Bio-rock was 2 times higher than T-N and T-P in treatment efficiency. And electron-microscopic examination showed that Bio-rock was more favorable to microbial adherence than gravel. The microbial populations were $5.2{\times}10^6\;CFU/mL$ of Bio-rock reactor compared to $2.6{\times}10^6\;CFU/mL$ in gravel reactor. In result Bio-rock was favor to microbial adherence and high treatment efficiency in spite of variation of influent concentration which had the advantages in saving running time and reducing site requirement.

• Analytical Science and Technology
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• v.11 no.5
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• pp.347-352
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• 1998

A study was carried out on the elelctrochemical characteristics of chemically modified electrodes (CMEs) by cyclic voltammetry. Fabrication of CMEs was made by coating with mixed valence (mv) inorganic-metal polymeric films on the glassy carbon electrode surface by potential cycling. Anodic oxidation behavior of methanol and L-ascorbic acid was studied by using CMEs working electrode. Deposition of films such as mv ruthenium oxo/ruthenium cyanide film (mv Ru-O/CN-Ru), mv ruthenium oxo/ferrocyanide film (mv Ru-O/$Fe(CN)_6$), and mv ruthenium oxo/ruthenium cyanide/Rhodium film (mv Ru-O/CN-Ru/Rh) was obtained to coat by scan rate of 50 mV/sec within the specified potential range (-0.5V ~ +1.2V). Film thickness was controlled by the repeat of the potential cycling. Anodic oxidation behavior of methanol was as follow. Calibration graph by using mv Ru-O/CN-Ru film showed linearly from 10 mM to 80 mM MeOH with slope factor of $-7.552{\mu}A/cm^2$. Although slope factor by using mv Ru-O/$Fe(CN)_6$ film was $-5.13{\mu}A/cm^2$, yet linear range of calibration graph could be extended from 10 mM to 100 mM MeOH. Anodic oxidation behavior of L-ascorbic acid was studied by mv Ru-O/CN-Ru film on the glassy carbon electrode and the glassy carbon electrode with Rh film, Glassy carbon electrode modified with Ru polymeric film was showed better sensitivity than the Rh-glassy carbon modified electrode (mv Ru-O/CN-Ru/Rh). Calibration graph was linear from 0.1 mM to 5 mM L-ascorbic acid by using glassy carbon electrode modified with Ru polymeric film. Solpe factor and relative coefficient are $-84.78{\mu}A/mM$ and 0.998, respectively.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.391-396
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• 2010

In this research the characteristics of ammonia removal from malodorous waste-air were investigated under various operating condition of biofiilter packed with equal volume of rubber media and compost for the efficient removal of ammonia, representative source of malodor frequently generated at compost manufacturing factory and publicly owned facilities. Then the optimum conditions were constructed to treat waste-air containing ammonia with biofilter. Biofilter was run for 30 days(experimental frequency of 2 times/day makes 60 experimental times.) with the ammonia loading from $2.18g-N/m^3/h$ to $70g-N/m^3/h$ at $30^{\circ}C$. The ammonia removal efficiency reached almost 100% for I through IV stage of run to degrade up to the ammonia loading of $17g-N/m^3/h$. However the removal efficiency dropped to 80% when ammonia loading increased to $35g-N/m^3/h$, which makes the elimination capacity of ammonia $28g-N/m^3/h$ for V stage of run. However, the removal efficiency remained 80% and the maximum elimination capacity reached $55g-N/m^3/h$ when ammonia loading was doubled $70g-N/m^3/h$ for VI stage of run. Thus the maximum elimination capacity exceeded $1,200g-N/m^3/day$(i.e., $50g-N/m^3/h$) of the experiment of biofilter packed with rock wool inoculated with night soil sludge by Kim et al.. However, the critical loading did not exceed $810g-N/m^3/day$ (i.e., $33.75g-N/m^3/h$) of the biofilter experiment by Kim et al.. The reason to exceed the maximum elimination capacity of Kim et al. may be attributed to that the rubber media used as biofilter packing material provide the better environment for the fixation of nitrifying and denitrification bacteria to its surface coated with coconut based-activated carbon powder and well-developed inner-pores, respectively.

• KSBB Journal
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• v.24 no.1
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• pp.30-40
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• 2009

Statistical optimization of the production medium was carried out in order to find an optimal medium composition in itaconic acid fermentation process. Itaconic acid utilized in the manufacture of various synthetic resins is a dicarboxylic acid biosynthesized by fungal cells of Aspergillus terreus in a branch of the TCA cycle via decarboxylation of cis-aconitate. Through OFAT (one factor at a time) experiments, six components (glucose, fructose, sucrose, soluble starch, soybean meal and cottonseed flour) were found to have significant effects on itaconic production among various carbon- and nitrogen-sources. Hence, using these six factors, interactive effects were investigated via fractional factorial design, showing that the initial concentrations of sucrose and cottonseed flour should be high for enhanced production of itaconic acid. Furthermore, through full factorial design (FFD) experiments, negative effects of $KH_2PO_4$ and $MgSO_4$ on itaconic acid biosynthesis were demonstrated, when excess amounts of the each component were initially added. Based on the FFD analysis, further statistical experiments were conducted along the steepest ascent path, followed by response surface method (RSM) in order to obtain optimal concentrations of the constituent nutrients. As a result, optimized concentrations of sucrose and cottonseed flour were found to be 90.4g/L and 53.8g/L respectively, with the corresponding production level of itaconic acid to be 4.36 g/L (about 7 fold higher productivity as compared to the previous production medium). From these experimental results, it was assumed that optimum ratio of the constituent carbon (sucrose) and nitrogen (cottonseed flour) sources was one of the most important factors for the enhanced production of itaconic acid.

• Journal of the Mineralogical Society of Korea
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• v.22 no.2
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• pp.139-151
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• 2009

Mineralogical characteristics of secondary precipitate formed at some mineral water springs in Gyeongbuk Province, Korea were studied in relation to water chemistry. The chemical water types of mineral water springs are mostly classified as $Ca-HCO_3$ type, but $Na(Ca)-HCO_3$ and $Ca-SO_4$ types are also recognized. Ca, Fe, and $HCO_3\;^-$ are the most abundant components in the water. The pH values of most springs lie in 5.76${\sim}$6.81, except Hwangsu spring having pH 2.8. Saturation indices show that all springs are supersaturated with respect to iron minerals and oxyhydroxides such as hematite and goethite. The result of particle size analysis shows that the precipitate is composed of the composite with various sizes, indicating the presence of iron minerals susceptible to a phase transition at varying water chemistry or the mixtures consisting of various mineral species. The particle size of the reddish precipitate is larger than that of the yellow brown precipitate. Based on XRD and SEM analyses, the precipitate is mostly composed of ferrihydrite (two-line type), goethite, schwertmannite, and calcite, with lesser silicates and manganese minerals. The most abundant mineral fanned at springs is ferrihydrite whose crystals are $0.1{\sim}2\;{\mu}m$ with an average of $0.5\;{\mu}m$ in size, characterized by a spherical form. It should be interestingly noted that schwertmannite forms at Hwangsu spring whose pH is very low. At Shinchon spring, Gallionella ferruginea, one of the iron bacteria, is commonly found as an indicator of the important microbial activity ascribed to the formation of iron minerals because very fine iron oxides with a spherical form are closely distributed on surfaces of the bacteria. A genetic relationship between the water chemistry and the formation of the secondary precipitate from mineral water springs was discussed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.4
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• pp.503-526
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• 1996

A synoptic survery of chemical characteristics in the last Sea of Korea was carried out at the 11 stations near Ullungdo in November, 1994 on board R/V Tam-Yang. On the basis of the vortical distribution patterns of temperature, salinity and dissolved oxygen, water masses in the study area are divided into five groups; 1) Tsushima Surface Water (TSW), 2) Tsushima Middle Water (TMW), 3) East Sea Intermediate Water (ESIW), 4) last Sea Proper Water (ESPW), 5) Mixed Water (MW). In the vertical profiles of nutrients, the concentrations were very low in the surface layer and increased rapidly near the thermocline. There was a slight decrease in the ESIW and the concentrations were constant with the depth below 300m except dissolved silicate which still increased with depth. Relatively high value of Si/P ratio (25.2) in ESPW, whick is the oldest water mass, suggests that Si is regenerating more slowly compared to other nutrients. The relatively high value of N/P ratio (18.6) in the surface layer might be related to high vertical eddy diffusivity $(K_z)$ of $1.19\;cm^{2}/sec$ and high nitrate upward flux of $103.7\;{\mu}g-at/m^{2}/hr$, compared to the values reported in other areas. Apparent Oxygen Utilization (AOU) was very low in the surface layer and increased in the TMW, but there was a slight decrease in the ESIW. The highest value of AOU occurred in the ESPW. The slpoe of P/AOU was 0.50. The study on the relationship between water masses and nutrient distribution patterns is important in understanding the regeneration processes of nutrients in the polar region of the last Sea.