• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.712-718
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• 2005

Stepwise reductions of glucose and Orange II concentration were observed from the experiment of both white-rot fungi such as T. versicolor and P. chrysosporium. As a result, typical removal patterns in those dual substrate system were categorized through several distinctive steps: initial lag period, primary and secondary carbon consumption periods. Also, based on the total removal amounts of Orange II, COD and Color during the experimental period, similar removal extent were observed from both species experiments, within the maximal error range of 5%. However, it was refereed that the internal steps of Orange II removal on enzymatic level should be different between two species: Enzyme Lac showed good affinity for Orange II removal in T. versicolor, however in P. chrysosporium enzyme LiP represented more close affinity to the similar experimental condition. Thus, even though the superficial removal amount of calcitrant Orange II at different fungal species was merely similar, removal pathway of enzymatic levels and intermediates produced during the fungal decomposition would be different.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.6
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• pp.375-382
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• 2023

The binary oxide adsorbent using Fe and Mn (Fe-Mn) has been prepared by precipitation method to enhance the removal of phosphate. Different amounts of chitosan, a natural organic polymer, were used during preparation of Fe-Mn as a stabilizer to protect an aggregation of Fe-Mn particles. The optimal amount of chitosan has been determined considering the separation of the Fe-Mn particles by gravity from solution and highest removal efficiency of phosphate (Fe-Mn10). The application of Fe-Mn10 increased removal efficiency at least 15% compared to bare Fe-Mn. According to the Langmuir isotherm model, the maximum uptake (q_m) and affinity coefficient (b) were calculated to be 184 and 240 mg/g, and 4.28 and 7.30 L/mg for Fe-Mn and Fe-Mn10, respectively, indicating 30% and 70% increase. The effect of pH showed that the removal efficiency of phosphate was decrease with increase of pH regardless of type of adsorbent. The enhanced removal efficiency for Fe-Mn10 was maintained in entire range of pH. In the kinetics, both adsorbents obtained 70% removal efficiency within 5 min and 90% removal efficiency was achieved at 1 h. Pseudo second order (PSO) kinetic model showed higher correlation of determination (R²), suggesting chemisorption was the primary phosphate adsorption for both Fe-Mn and Fe-Mn10.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.327-334
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• 2004

In this paper, method for the determination of removal time of the side forms in high strength concrete are discussed using the estimation model of compressive strength development, the development of bond strength and rebound number of P type Schmidt hammer in order to review the validity of existing regulation as to side form removal and offer effective quality control method. According to the results, as W/B increases by $10\%$, the setting time is shortened by about 2 hours. In the scope of the paper, required time to gain 8MPa of compressive strength is determined about 17 ${\~}$20 hours of age and $21{\~}25^{\circ}D{\cdot}D$ of maturity. Bond strength between form and concrete shows the highest value around final setting time, but decreases drastically after that. Amount of concrete sticking on the form is large before setting completed, but after that, its amount shows decline tendency. The rebound value test with P type schmidt hammer can be started faster by 2${\~}$3 hours than compressive strength test. It is also confirmed that the removal of forms is possible when the rebound value of P type schmidt hammer is more than 32. It is found from the results that existing regulation regarding removal time of the side form of high strength concrete provided in KCI needs no revision because required time to gain the strength provided in KCI has no adverse effect on strength development at early age and surface condition during stripping the side form. Effective procedure to decide the removal time of side form can be performed by applying P type Schmidt hammer.

• International Journal of Highway Engineering
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• v.16 no.5
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• pp.49-58
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• 2014

PURPOSES : In areas of high traffic volume, such as expressway across large cities, the amount of nitrogen oxides (NOx) emitted into the atmosphere as air pollution can be significant since NOx gases are the major cause of smog and acid rain. Recently, the importance of NOx removal has arisen in the world. Titanium dioxide ($TiO_2$), that is one of photocatalytic reaction material, is very efficient for removing NOx. The NOx removing mechanism of $TiO_2$ is the reaction of solar photocatalysis. Therefore, $TiO_2$ in road structure concrete need to be contacted with ultraviolet rays (UV) to be activated. In general, $TiO_2$ concretes are produced by replacement of $TiO_2$ as a part of concrete binder. However, considerable portion of $TiO_2$ in concrete cannot contact with the pollutant in the air and UV. Therefore, $TiO_2$ penetration method using the surface penetration agents is attempted as an alternative in order to locate $TiO_2$ to the surface of concrete structure. METHODS : This study aimed to evaluate the NOx removal efficiency of photocatalytic concrete due to various $TiO_2$ application method such as mix with $TiO_2$, surface spray($TiO_2$ penetration method) on hardened concrete and fresh concrete using surface penetration agents. The NOx removal efficiency of $TiO_2$ concrete was confirmed by NOx Analyzing System based on the specification of ISO 22197-1. RESULTS : The NOx removal efficiency of mix with $TiO_2$ increased from 11 to 25% with increasing of replacement ratio from 3 to 7%. In case of surface spray on hardened concrete, the NOx removal efficiency was about 50% due to application amount of $TiO_2$ with surface penetration agents as 300, 500 and 700g/m2. The NOx removal efficiency of surface spray on fresh concrete due to all experimental conditions, on the other hand, which was very low within 10%. CONCLUSIONS : It was known that the $TiO_2$ penetration method as surface spray on hardened concrete was a good alternative in order to remove the NOx gases for concrete road structures.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.143-148
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• 2011

In this work, a composite formed by adding loess with lanthanium ("La-Loess") was proposed for effective removal of phosphate found in confined water bodies such as lake and reservoir. It was found that the theoretical maximum amount of lanthanum that can be attached to Loess was 2.68 mg La/g Loess. The phosphate removal was enhanced as an added amount of La-Loess composite increased. Furthermore, there was a noticeable difference in phosphate removal between Loess and La-Loess as the latter required 1.5 to 10 times less Loess than the former. Both Isotherm equations of Freundlich and Langmuir can be used to explain the phosphate adsorption characteristics in using La-Loess composites. The phosphate removal was very effective in the pH range of 5~8, which means that the proposed adsorbent can be directly applied to natural water without adjusting pH. Also, the La-Loess composites were well settled within 30 min without causing turbidity in water. Consequently, the proposed La-Loess can be strongly recommended for phosphate removal in confined water bodies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.2
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• pp.146-154
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• 2002

To assess the adsorption and removal mechanism of dissolved inorganic nutrients in seawater by scattering yellow loess, a laboratory experiment was conducted for the change of nutrient concentration in seawater during the course of time depending on particle size and scattered concentration of the yellow loess. Twenty four hours after the addition of yellow loess in the size range of 0 $\mu$m to 500 $\mu$m in seawater, the removal rate of dissolved inorganic phosphorus (DIP) was increased with increasing amount of yellow loess. There was little difference among the removal rates depending on the size of yellow loess. On average, $26\%$ of dissolved inorganic silicate was reduced for the same period. No greate difference among the removal rate depending on both size and amount of yellow loess was found. Our results suggested that the removal mechanism of DU seemed to be associated with mostly the chemical bond with iron. More than $99\%$ of initial DU concentration was likely to be removed by this mechanism. In the case of inorganic dissolved silicate, the removal mechanism was likely to be attributed to a cation exchange between the yellow loess and seawater.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.45-46
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• 2000

After cell removal from fermentation broth the supernatant containing poly (${\gamma}-glutamic acid$) (${\gamma}-PGA$) was concentrated by ultrafiltration in order to reduce the amount of organic solvents such as methanol, ethanol, propanol required for the recover of ${\gamma}-PGA$ with precipitation. The concentration and volume reduction of cell-free solution by ultrafiltration could reduce 3 times the amount of ethanol for the recover of ${\gamma}-PGA$ from cell-free fermentation broth.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.152-165
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• 1991

Elasto-plastic and Visco-elastic sytress analyses were conducted for standard cross-section of subway tunnel in Seoul . Considering the procedure of excavation and reinforcement, excavated region was divided to multiple elements. And the progress of tunnel is simulated to be the removal of a series of layerd elements by means of diminishing the stiffness of the portion progressively. Another method is to be free of stress due to excavation instead of stiffness. In the analysis multiple element method was conducted with ADINA program, the stiffness removal method was adopted . For the same model, stress release method was carried out with Visco-Elastic Analysis program developed in Rock mechanics laboratory, Seoul National University(SNU-VBA) . When upper tunnel excavated, displacements in roof were same for two results, but when bottom tunnel removed completely , displacement changes of rock in the stress release method exhibited very small amount compared with stiffness removal method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.622-625
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• 2004

The CMP monitoring system was newly developed by the aid of friction force measurement, resulting from installation of piezoelectric quartz sensor on R&D polisher. The correlation between friction and CMP results was investigated in terms of tribological aspects by using the monitoring system. Various friction signals were monitored and analyzed by the change of experimental conditions such as pressure, velocity, pad and slurry. First of all, the lubrication regimes were classified with Sommerfeld Number through measuring coefficient of friction in ILD CMP. And then, the removal mechanism of abrasives could be understood through the correlation with removal rate and coefficient of friction. Especially, the amount of material removal per unit sliding distance is directly proportional to the friction force. The uniformity of CMP performances was also deteriorated as coefficient of friction increased.

• Journal of Environmental Science International
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• v.6 no.5
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• pp.531-539
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• 1997

Lead sorption performances by biomass of nonliving, dried marine brown algae Undaria phnaunda, Hlzikia hsyormls. and Sugassum fulvellum used as biosorbent materials were investigated. As the amount of biosorbent materials added was increased, the lead removal by biosorbent materials Increased but the lead biosorption capacities decreased. However, with increasing Initial lead concentration the lead biosorption capacities by the biosorbent materials Increased but lead removal efficiencies decreased. In the range of Initial lead concentration(Co) 10-500 mg/L the lead biosorption capacities and removal efficiencies by the biosorbent materials Increased with increasing pH. Among the biosorbent materials used in this study, the lead biosorption capacities decreased in the following sequence: U. plilnaunda > H. fusiformis > S. fulvellum. The lead biosorption by biosorbent materials were expressed by the Langmuir Isotherm better than the Freundlich Isotherm. The biosorption rate could be expressed by the first order reaction rate equation for initial lead concentration like that rad : 0.288Co for U. phanda, rad = 0.255Co for H. fusiformis, and rad : 0.161Co for S. fulvellum. Key words : Lead, biosorption, biosorbent, Undaria pinnatinda, Hiztkia fusiformis, Sargassum fulvellum, Langmuir isotherm, Freundlich isotherm, biosorption rate.