• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1107-1112
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• 2008

Crystallization of calcium carbonate was performed by using aqueous calcium chloride and sodium carbonate for operational simplicity. Reaction time, solute concentrations, pH, and organic additive were varied to get calcium carbonate crystals. Silk fibroin was used as the additive to understand the change of morphology of calcium carbonate crystal. The crystals were analyzed by FE-SEM, XRD, and FT-IR. Reaction time, and pH mainly affected the morphology of crystals. Besides, it was found that silk fibroin inhibited the formation of vaterite and promoted the calcite forms.

• Journal of the Korean Geotechnical Society
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• v.28 no.9
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• pp.85-95
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• 2012

The method of using organic acid is more environment-friendly for it improves the strength of the ground. The method of proliferating microbes makes soil particle bonded, finally improves the strength of the ground and decreasing permeability. Although there has been the research on the effect of strength increasing, there has never been a research on the evaluation of field application. In this paper, through the light drop weight test, the dynamic cone penetration test, the field density test, the variation of strength was investigated in the mixed ground with organic acid for 56 days. As the results of the field test, it was found that the strength and stiffness of the ground increased with organic acid, and that through SEM-EDS, the precipitation of calcium carbonate made by specified microbe obviously increased with organic acid material and so the ground was improved. Therefore, the sustainable development of this method needs to be analysed more in the future.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.242-246
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• 2011

Organic kiwifruit orchard soils were compared with conventional ones in Korea. Soil structure of organic soil had higher gaseous and liquous phase as well as soil porosity in the surface soil. Although the nutritional level of each orchards were quite different among soils, the analysis of both system revealed that organic kiwifruit orchard soil had similar or even higher nutrient level (N and organic matter content in surface soil) compared to conventional ones. The organic matter content of deep soil also had the high tendency in deep soil of organic soil. Higher level of nitrogen in organic surface soil is presumably due to the excessive application of organic compost and liquid fertilizer rather than the contribution by grasses such as green manure. Available phosphorous level of organic system was quite high but similar in surface soil of both system, compared to the recommended level. Potassium, calcium and magnesium levels were also enough in organic kiwifruit orchard soils.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.67.1-67.1
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• 2000

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.2
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• pp.140-145
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• 2006

The behaviour of alginate immobilized and soluble watermelon (Citrullus vulgaris) urease in water miscible organic solvents like, acetonitrile, dimethylformamide (DMF), ethanol, methanol, and propanol is described. The organic solvents exhibited a concentration dependent inhibitory effect on both the immobilized and the soluble urease in the presence of urea. Pretreatment of soluble enzyme preparations with organic solvents in the absence of substrate for 10 min at $30^{\circ}C$ led to rapid loss in the activity, while similar pretreatment of immobilized urease with 50% (v/v) of ethanol, propanol, and acetonitrile was ineffective. Time-dependent inactivation of immobilized urease, both in the presence and in the absence of urea, revealed stability for longer duration of time even at very high concentration of organic solvents. The soluble enzyme, on the other hand, was rapidly inactivated even at fairly lower concentrations. The results suggest that the immobilization of watermelon urease in calcium alginate make it suitable for its application in organic media. The observations are discussed.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.1
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• pp.139-147
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• 2002

In order to the development of a new organic compost to exclusive use in a ginseng, we conducted the study of the preparation of organic fertilizer and the application effect of organic fertilizer in cultivation of ginseng. The new organic compost was composed of dryed broad leaves of acorn 40%, puffed husks of rice 40% and organic material mixture 20%. The chemical properties of the organic compost shown that the values of the total nitrogen, available phosphate, pottasium, calcium, magnesium, organic matter and C/N ratio were $17g\;kg^{-1}$, $8g\;kg^{-1}$, $11g\;kg^{-1}$, $14g\;kg^{-1}$, $4g\;kg^{-1}$, $794g\;kg^{-1}$, and 26.7, respectivly. The application effect of organic compost in the cultivation of ginseng shown that survival ratio of above ground plant of ginseng was shown the high value than control, and the ratio of root rot and red colored root were decreased. The optimal amount of organic fertilizer for ginseng seedling was $24M/T\;ha^{-1}$. The chemical properties of the ferilized soil were analyzed.

• Journal of Environmental Science International
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• v.8 no.6
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• pp.717-724
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• 1999

This experiment was performed on three parts with prepared coagulants. (1) The characterization of coagulation for PACI coagulants. (2) Comparison of the characterization of coagulation with PAS and PACI coagulants. And (3) Comparison of the characterization of coagulation for the addition of calcium with PACI. Coagulation experiments were conducted with several dosages and pH for each coagulants. For the characterization of coagulation with PACI coagulants, coagulation of Nakdong river waters with three PACls (r=2.0, 2.2, 2.35) showed that the effectiveness of the three coagulants can be considered as r=2.2 > 2.0 > 2.35 which are also the order of higher polymeric aluminum contents. For the comparison of the characterization of coagulation for PAS and PACI coagulants, PAS (r=0.75) coagulants was more effective than other coagulant for the removal of organic matters by sweep floc mechanism with $A;(OH)_{3(S)}$. For comparison of the characterization of coagulation for the addition of calcium with PACI, the presence of divalent cation like $Ca^{2+}$ was supposed to influence the complex formation of organic anions. From the result of test on coagulation at various pH ranges, the PACI was least affected by the coagulation pH, and the addition of calcium to PACI was very effective for the removal of turbidity and organic materials over broader pH range (pH 4-9).

• Journal of Practical Agriculture & Fisheries Research
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• v.13 no.1
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• pp.35-46
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• 2011

The effects of organic calcium agent(ECa) tree-spray on the mineral nutrition concentration of petiole and fruit skin and quality in grapevines were studied. The calcium concentration of petiole and fruit skin at harvest in 'Campbell Early' by tree-spray after flowering 14days of calcium agent were increased significantly in calcium chloride 0.4%, ECa 250X and MCa 500X compared to control. The calcium concentration of petiole and fruit skin at harvest by ECa tree-spray after 7 days and 14 days flowering were increased significantly compared to control and 21 days after flowering treatment. Also, The calcium concentration of petiole and fruit skin at harvest by tree-spray of ECa 250X and 125X after flowering were increased significantly compared to control and 500X treatment. Fruit quality, fruit cluster weight, cracking fruit and Bitter rot occurrence by ECa tree-spray of treatment time and concentration different showed no difference between control. Phytotoxicity by tree-spray of ECa concentration different not occur to leaf and fruit.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.4
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• pp.436-444
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• 2016

Clamshells, which comprise more than 50% of a clam’s weight, are a major byproduct of the clam industry and are mainly composed of insoluble calcium carbonate. This study investigates the use of clamshells as a natural calcium resource. Highly soluble powdered calcium lactate (LCCL) was prepared from the calcined powdered shells of littleneck clams (LCCP) using response surface methodology (RSM) to predict optimum conditions. These conditions, as derived from pH, solubility, and yield of 11 LCCLs manufactured according to the RSM model, were 1.80 M lactic acid and 1.13 M LCCP. The actual values of pH (6.98), solubility (93.99%), and yield (351.23%) under the optimized conditions were as predicted. The derived LCCL exhibited a strong buffering capacity in the range of pH 2.78-3.90 when combined with less than 2 mL of 1 N HCl. The ranges of calcium content and solubility of LCCL were 7.7-17.5 g/100 g and 96.6-98.9%, respectively. Fourier transform infrared spectroscopy (FT-IR) of the LCCL identified it as calcium lactate pentahydrate, and field emission scanning electron microscopy (FESEM) revealed an irregular and rod-like microstructure. These results confirm the potential use of clamshells, converted to highly soluble organic acid calcium, as an additive to enhance calcium content in food ingredients.

• The Korean Journal of Ecology
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• v.23 no.2
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• pp.83-88
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• 2000

When interpreting change over time in forest ecosystems, distinguishing the effects of forest succession from the effects of environmental stress can be difficult. The result may be a simplistic interpretation. citing a specific successional or environmental cause of forest change when both types may be occurring. We present two case studies of changes in the forest floor in northern hardwoods. First, the belief that 50% of soil organic matter is lost in the first 20 years after logging was based on a study comparing northern hardwood stands of different ages. We resampled a series of 13 such stands after an interval of 15 years, and found that the young stands were not, in fact. losing organic matter as rapidly as predicted from the original chronosequence study. The pattern of higher organic matter content in the forest floors of older stands compared to young stands could be equally well explained by changes in logging practices over the last century as by the aging of the stand. The observed pattern of forest floor organic matter as a function of stand age was previously interpreted as a successional pattern, ignoring changes in treatment history. In the second case study, observed losses of base cations from the forest floor were attributed to cation depletion caused by acid rain and declining calcium deposition. We found that young stands were gaining base cations in the forest floor; losses of base cations were restricted to older stands. Differences in litter chemistry in stands of different ages may explain some of the pattern in cation gains and losses. In this case, the contribution of successional processes to cation loss had been overlooked in favor of environmental stress as the dominant mechanism behind the observed changes. Studies of environmental stress use repeated measures over time. but often don't consider stand age as a factor. Studies of successional change often assume that environmental factors remain constant. We were able to consider both forest succession and external factors because we repeatedly sampled stands of different ages.