• Journal of the Korean Institute of Intelligent Systems
• /
• v.25 no.4
• /
• pp.369-376
• /
• 2015

Chemicals are injected in order to remove a variety of organic substances contained in the water purification plant influent. It can be determined with measuring sedimentation turbidity 4~7 hours later, whether the chemical dosage rate is proper or not, which make the real-time feedback control impossible. In addition, manual operation in accordance with the Jar-Test carried out in the laboratory and the operator's experience may cause the experimental and human error by the changes of organic characteristics and water quality. Especially at night ad weekend, the rate have been determined only by the operator judgment owing to environment engineer's absence. Therefore, the decision of optimal chemical dosage rate using proposed intelligent control algorithm is expected to result in real-time injection and cost reduction.

• Journal of the Korean Ceramic Society
• /
• v.41 no.10 s.269
• /
• pp.749-755
• /
• 2004

Fluosilicic acid ($H_2SiF_6$) is recovered as aqueous solution which absorbs $SiF_4$ produced from the manufacturing of industrial-graded $H_3PO_4$ or HF. Generally, fluosilicate salts prepared by the reaction between $H_2SiF_6$ and metal salts. Addition of fluosilicate salts to cement endows odd properties through unique chemical reaction with the fresh and hardened cement. In this study, two-component fluosilicate salt based chemical admixtures (MZ) of $4\%,\;6\%$, and $8\%$ concentration were prepared by the reaction of $H_2SiF_6$ ($25\pm2\%$) and metal salts. The effect of concentration of MZ at a constant adding ratio on the hydration and watertightness of cement were investigated respectively. In a cement containing MZ, metal fluorides such as $CaF_2$ and soluble silica by hydrolysis were newly formed during hydration. The total porosity of the hardened cement was lower in the presence of U because of packing role of metal fluoride and pozzolanic reaction of soluble $SiO_2$. Consequently, the watertightness of the hardened paste containing MZ was more improved than non-added (plain) due to an odd hydration between cement and MZ.

• Korean journal of applied entomology
• /
• v.26 no.4 s.73
• /
• pp.251-255
• /
• 1987

This study was conducted to investigate the effects of cultural methods on infection by Rhizoctonia disease(Rhizoctonia solani $K\"{u}hn$) of potato (Solanum tuberosum L.). Two potato cultivars, i.e., Irish Cobbler and Superior were planted in 1984 at the Alpine Experiment Station and 4 cultural methods were used in Combinations or separately. The deeper planting showed the later germination of sprout. The degree of infection on underground stems didn't show any differences between the treatments, but the yield was higher in deeper planting. When seed tubers were planted on April 28 the underground stems showed severely discolourated epidermis comparing to later planting, consequently the yield was low. The glazed chitting tubers produced healthy sprouts comparing to the untreated tubers, consequently the yield was also increased. The density of sclerotia on tuber skin was remarkably increased between 6 to 15days of delayed digging after haulm killing. Underground stems of Irish Cobbler were easily discolourated by the disease, where-as the density of sclerotia was higher on tuberskin of Superior than of Irish Cobbler.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.21 no.2
• /
• pp.195-200
• /
• 1992

Rhizopus oryzae CJ-2114 was selected for its strong polygalacturonase activity among various strains of mold found in soil. The optimum pH for the enzyme activity was 4.0 and optimum temperature was 4$0^{\circ}C$. The activation energy for the polygalacturonase was calculated by Arrhenius equation was 2.048㎉/㏖. The reaction of this enzyme followed typical Michaelis-Menten kinetics with the Km value of 54.05mM with the $V_{max}$ of 13.9m mole/min. The enzyme is relatively stable in acidic condition. The activity of polygalactur-onase was inhibited completely by C $u^{2+}$, P $b^{2+}$ and Z $n^{2+}$, $_Mn^{2+}$ at concentration of 1 mM. The enzyme can be inactivated by the treatment with maleic anhydride and iodine. The results indicate the possible involvement of histidine at active site. When polygalacturonase from Rhizopus oryzae CJ-2114 was reacted with poly-galacturonic acid as a substrate mono-, di-, and oligogalacturonic acid were produced at early and mono-, digalacturonic acid produced at late incubation time. time.

• Journal of Korean Society of Forest Science
• /
• v.85 no.3
• /
• pp.381-395
• /
• 1996

This study examines the nature of policies of the national forest in the colonial Korea during the period 1926-36. The contents of Choson Forestry Policy Plan announced in 1926 by the colonial government were compared with the actual accomplishments appearing in the historical records. The Plan is believed to have two-fold objectives : that is, the attainment of sustainable profits from the management of national forests and the restructuring of the national forest management organizations for the minimization of administration costs of the colonial government. The objectives of the Plan was framed by the influence of the Imperial Japanese Government. The analysis reveals that the timber supply from national forests was increased by two folds during the period of 10 years resulting an enormous decrease in the growing stock of national forests. The number of national forest management stations was decreased steadily while the regeneration of forest logged relied mainly on the natural regeneration, with artificial regeneration ratio of 13% by acreage. Based on the result of analysis, it is concluded that the national forest policy during the period 1926-36 is a resource exploiting policy for the benefit of the Imperial Japan.

• Journal of the Korea Convergence Society
• /
• v.13 no.4
• /
• pp.127-135
• /
• 2022

This study intends to provide basic data to confirm the convergence effects of economic activity on the quality of life and oral health of middle-aged Korean women. Data from the 2019 National Health and Nutrition Examination Survey were used, and complex sample logistic regression analysis and linear regression analysis were performed to confirm the effect of economic activity on health-related quality of life (Korean Health-related Quality of Life Instrument with 8 Items; HINT-8) and oral health-related factors. As a result, in the case of controlling for demographic characteristics and economic activity, there was a significant effect in 4 items (energy, work, memory, sleep) out of HINT-8. When the oral health status was adjusted, there was a significant effect only in 2 items (working and memory) of HINT-8 (p<.05). Therefore, although economic activity of middle-aged Korean women has a positive effect on quality of life, it is considered to be valuable in that oral health status can reduce the influencing factors.

• Composites Research
• /
• v.16 no.2
• /
• pp.54-61
• /
• 2003

In this study, manufacturing process for microcapsules with the self-healing agent was introduced and the characteristics of microcapsules manufactured by varying with various manufacturing process variables were evaluated through a particle size analyzer, an optical microscope, and a TGA. Urea-formaldehyde resin was used for the thin wall of microcapsules and DCPD (dicyclopentadiene) was used for the self-healing agent. The various manufacturing process variables, such as (1) 24hr, 40hr, 48hr, 60hr of the solution time of the EMA copolymer, (2) pH3.5, pH4.0, pH4.5 of the hydrogen ion concentration of the emulsified solution, (3) 400rpm, 500rpm, 600rpm, 1000rpm of the agitation speed of the emulsified solution, (4) $50^{\circ}$, $55^{\circ}$, $60^{\circ}$ of the reaction temperature of the emulsified solution, were considered. According to the results, the particle size distribution of microcapsules was affected on the agitation speed, and the thermal stability of microcapsules was influenced by the solution time of the EMA copolymer, the hydrogen ion concentration, and the reaction temperature of the emulsified solution. Therefore, suitable manufacturing process variables should be applied to obtain thermally stable microcapsules capable of containing the healing agent capable until the thin wall of microcapsules were to be burned.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.11 no.4
• /
• pp.1775-1782
• /
• 1969

The results of the study on the consumptine use of irrigated water in paddy fields during the growing season of rice plants are summarized as follows. 1. Transpiration and evaporation from water surface. 1) Amount of transpiration of rice plant increases gradually after transplantation and suddenly increases in the head swelling period and reaches the peak between the end of the head swelling poriod and early period of heading and flowering. (the sixth period for early maturing variety, the seventh period for medium or late maturing varieties), then it decreases gradually after that, for early, medium and late maturing varieties. 2) In the transpiration of rice plants there is hardly any difference among varieties up to the fifth period, but the early maturing variety is the most vigorous in the sixth period, and the late maturing variety is more vigorous than others continuously after the seventh period. 3) The amount of transpiration of the sixth period for early maturing variety of the seventh period for medium and late maturing variety in which transpiration is the most vigorous, is 15% or 16% of the total amount of transpiration through all periods. 4) Transpiration of rice plants must be determined by using transpiration intensity as the standard coefficient of computation of amount of transpiration, because it originates in the physiological action.(Table 7) 5) Transpiration ratio of rice plants is approximately 450 to 480 6) Equations which are able to compute amount of transpiration of each variety up th the heading-flowering peried, in which the amount of transpiration of rice plants is the maximum in this study are as follows: Early maturing variety ; Y=0.658+1.088X Medium maturing variety ; Y=0.780+1.050X Late maturing variety ; Y=0.646+1.091X Y=amount of transpiration ; X=number of period. 7) As we know from figure 1 and 2, correlation between the amount evaporation from water surface in paddy fields and amount of transpiration shows high negative. 8) It is possible to calculate the amount of evaporation from the water surface in the paddy field for varieties used in this study on the base of ratio of it to amount of evaporation by atmometer(Table 11) and Table 10. Also the amount of evaporation from the water surface in the paddy field is to be computed by the following equations until the period in which it is the minimum quantity the sixth period for early maturing variety and the seventh period for medium or late maturing varieties. Early maturing variety ; Y=4.67-0.58X Medium maturing variety ; Y=4.70-0.59X Late maturing variety ; Y=4.71-0.59X Y=amount of evaporation from water surface in the paddy field X=number of period. 9) Changes in the amount of evapo-transpiration of each growing period have the same tendency as transpiration, and the maximum quantity of early maturing variety is in the sixth period and medium or late maturing varieties are in the seventh period. 10) The amount of evapo-transpiration can be calculated on the base of the evapo-transpiration intensity (Table 14) and Tablet 12, for varieties used in this study. Also, it is possible to compute it according to the following equations with in the period of maximum quantity. Early maturing variety ; Y=5.36+0.503X Medium maturing variety ; Y=5.41+0.456X Late maturing variety ; Y=5.80+0.494X Y=amount of evapo-transpiration. X=number of period. 11) Ratios of the total amount of evapo-transpiration to the total amount of evaporation by atmometer through all growing periods, are 1.23 for early maturing variety, 1.25 for medium maturing variety, 1.27 for late maturing variety, respectively. 12) Only air temperature shows high correlation in relation between amount of evapo-transpiration and climatic conditions from the viewpoint of Korean climatic conditions through all growing periods of rice plants. 2. Amount of percolation 1) The amount of percolation for computation of planning water requirment ought to depend on water holding dates. 3. Available rainfall 1) The available rainfall and its coefficient of each period during the growing season of paddy fields are shown in Table 8. 2) The ratio (available coefficient) of available rainfall to the amount of rainfall during the growing season of paddy fields seems to be from 65% to 75% as the standard in Korea. 3) Available rainfall during the growing season of paddy fields in the common year is estimated to be about 550 millimeters. 4. Effects to be influenced upon percolation by transpiration of rice plants. 1) The stronger absorbtive action is, the more the amount of percolation decreases, because absorbtive action of rice plant roots influence upon percolation(Table 21, Table 22) 2) In case of planting of rice plants, there are several entirely different changes in the amount of percolation in the forenoon, at night and in the afternoon during the growing season, that is, is the morning and at night, the amount of percolation increases gradually after transplantation to the peak in the end of July or the early part of August (wast or soil temperature is the highest), and it decreases gradually after that, neverthless, in the afternoon, it decreases gradually after transplantation to be at the minimum in the middle of August, and it increases gradually after that. 3) In spite of the increasing amount of transpiration, the amount of daytime percolation decreases gadually after transplantation and appears to suddenly decrease about head swelling dates or heading-flowering period, but it begins to increase suddenly at the end of August again. 4) Changs of amount of percolation during all growing periods show some variable phenomena, that is, amount of percolation decreases after the end of July, and it increases in end August again, also it decreases after that once more. This phenomena may be influenced complexly from water or soil temperature(night time and forenoon) as absorbtive action of rice plant roots. 5) Correlation between the amount of daytime percolation and the amount of transpiration shows high negative, amount of night percolation is influenced by water or soil temperature, but there is little no influence by transpiration. It is estimated that the amount of a daily percolation is more influenced by of other causes than transpiration. 6) Correlation between the amount of night percoe, lation and water or soil temp tureshows high positive, but there is not any correlation between the amount of forenoon percolation or afternoon percolation and water of soil temperature. 7) There is high positive correlation which is r=+0.8382 between the amount of daily percolation of planting pot of rice plant and amount and amount of daily percolation of non-planting pot. 8) The total amount of percolation through all growin. periods of rice plants may be influenced more from specific permeability of soil, water of soil temperature, and otheres than transpiration of rice plants.

• Composites Research
• /
• v.12 no.4
• /
• pp.71-78
• /
• 1999

To determine the effect of chemical structure of linear amine curing agents on thermal and mechanical properties, standard epoxy resin DGEBA was cured with diaminodiphenyl methane (DDM), diaminodiphenyl sulphone (DDS) in a stoichiometrically equivalent ratio. From this work, the effect of aromatic amine curing agents. In contrast, the results show that the DGEBA/DDS cure system having the sulfone structure between the benzene rings had higher values in the conversion of epoxide, density, shrinkage (%), glass transition temperature, tensile modulus and strength, flexural modulus and strength than the DGEBA/DDM cure system having methylene structure between the benzene rings, whereas the DGEBA/DDM cure system presented higher values in the maximum exothermic temperature, thermal expansion coefficient, and thermal stability. These results are caused by the relative effects of sulfone group having strong electronegativity and methylene group having (+) repulsive property and stem from the effect of the conversion ratio of epoxide group. The result of fractography shows that the each grain size of the DDM/DGEBA system with feather-like structure is larger than that of the DDS/DGEBA system.

• Applied Chemistry for Engineering
• /
• v.21 no.4
• /
• pp.463-468
• /
• 2010

The polycarboxylic (PC) type concrete superplasticizer was synthesized. The effects of ethylene oxide group number and its molecular weight on the properties of the polycarboxylic type concrete superplasticizer and the concrete motar properties were studied. To investigated of the interfacial properties of the premixed-concrete with the superplasticizer, the type and the amount of polyethylene glycol, meta acrylate added, and type of the initialization agent were studied. Also the interfacial properties of the superplasticizer aqueous phase, the wettability on the cement particle, the fluidity of the cement mortar, and the strength properties of the concrete were measured. For a high fluidity of the cement mortar and a high strength of concrete, a low value of the surface tension and contact angle were required for PC. To have a good performance for PC, the reaction condition of 1.3 mol ratio of MA against to MPEG was suitable with KSP initiator.