• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.1-9
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• 2022

De -icing salts have been used commonly in areas where snow or ice is a seasonal safety hazard for roadway, however, the salts is one of main causes on serious deterioration of road infrastructures in crowded urban city like Seoul. In order to establish maintenance strategy of road infrastructures under de-icing salts laden environment, it is necessary to examine environmental characteristics and its response to the existing facilities. The purpose of this study is to evaluate the deterioration environment of road infrastructures. Additional purpose is to develop a design model and details for durability design of infrastructures under de-icing salts laden environment, considering mainly a build-up rate of surface chlorides. Concentration of external chloride solution and surface chloride content were calculated at the level of average de-icing salts for 5 years, ratio of auxiliary road of 17.5 to 30%, and effective exposure area to snow 50 to 80%. The chloride build-up rate was 0.073 ~ 0.077% / year and the maximum surface chloride content was calculated to be 2.2 ~ 2.31% by concrete wt. This study is expected to be used for establishing integrated strategy of road infrastructures, such as predicting chloride profiles or degree of chemical corrosion to exposure concrete.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.606-614
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• 2003

The major cause of deterioration for the concrete bridge decks exposed to de-icing chemicals would be chloride-induced reinforcement corrosion. Thus, in this paper, in order to predict time to corrosion for concrete bridge decks in the urban area, chloride concentration was measured with depth from the surface. A frequency analysis on surface chloride concentration and chloride diffusion coefficient of concrete bridge deck equals 0.192, 29.828 in the scale parameter and 7.899, 1.983 in the shape parameter of gamma distribution. The average value of surface chloride concentration equals 1.5 kg/㎥ and condenses from 1 to 2 kg/㎥ in the level of probability 70%. From the probabilistic results, it is confirmed that 26mm of minimum cover depth in order to target 20 years over is calculated. The countermeasure strategy to extend the service life of concrete bridge deck exposed to de-icing chemicals would be an effective method to increase cover depth and to place high performance concrete, which could lead to reduce the chloride diffusion coefficient and distribution range.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.127-137
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• 2007

To confirm whether or not the Electrochemical Disinfection System (EDS) meet with the D-2 regulation established by IMO (International Maritime Organization), the biological treatment efficacy of the EDS was assessed using three groups of natural marine plankton (bacteria, $10-50\;{\mu}m$ and $>50\;{\mu}m$ sized organisms). Influent water was passed through the EDS under the flow velocity ($23.8\;m^3/hr$) and test design was consisted of control (no treatment) and experimental (10 ppm and 30 ppm) condition for total residual chlorine (TRC). And the biological condition of the influent water followed the standards established by the guidelines for the approval of ballast water management systems. The disinfection efficacy of the $10-50\;{\mu}m$ sized organisms (phytoplankton) was assessed by three kinds of measurements using photomicroscope, epifluorescence microscope and fluorometer (fumer Designs 10-AU). After being passed through the EDS, all motile phytoplankton lost their motility under photomicroscope, the colour of chlorophyll fluorescence fumed from red into green under epifluorescence, and the high chlorophyll fluorescence (Expt. 1: 6.95, Expt. 2: 7.11) detected by fluorometer decreased into value not detected. These results indicated phytoplankton community was totally killed after electrochemical disinfection treatment. Survivorship of the larger organisms than $50\;{\mu}m$ was determined based on the appendage's movement under a stereomicroscope. Natural assemblage collected from ambient seawater was killed shortly after being passed through the EDS, whereas some Artemia remained alive. However, no live Artemia was found after 24 hour further exposure to each TRC concentration (10 and 30 ppm) under darkness. After electrochemical treatment, the target bacteria such as aerobes, coliform and Escherichia coli were completely killed on the basis of CFU (colony forming unit) on Petrifilm plate ($3\;M^{TM}$) after 48 hr incubation. Moreover, no regrowth was found in the three groups of plankton during five days under additional exposure to the treated water. These results indicated that the disinfection efficiency of the EDS on the three groups of plankton satisfy D-2 regulation.

• Clinical and Experimental Pediatrics
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• v.49 no.12
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• pp.1275-1281
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• 2006

Purpose : Cerebral edema in meningitis is a potentially complication. Hypertonic saline of various concentrations are frequently used to treat cerebral edemas in meningitis. We analyzed the safety and efficacy of osmotic therapy in cerebral edema by comparison of various hypertonic saline concentrations and mannitol. Methods : The medical records of 42 patients, who were followed up in the Department of Pediatrics, Busan Medical Center, from Jan. 2002 to Oct. 2005, were analyzed retrospectively. We measured intracranial pressure, mean flow velocity, and various laboratory parameters. Results : In cerebral edema developed in meningitis, intracranial pressure and symptoms were improved in treatment of hypertonic saline and mannitol. Serial bolus infusion of 3 percent hypertonic saline resulted in the best outcome. There was not a statistically considerable difference on the mean values of the intracranial pressure gap. On transcranial doppler, mean flow velocity was increased and pulsatilty index was decreased. Laboratory findings (osmolarity, Na, Cl, pH, lactic acid, Ca) were diffenent during the treatment period as opposed to K, Hb, bicarbonate, base excess. There was not a specific form of hypertonic saline used in meningitis treatment with cerebral edema. Conclusion : The therapy for cerebral edema in meningitis remains largely empirical. Serial bolus infusion of 3 percent hypertonic saline is better than other hypertonic salines. Various concentrations and different infusion methods of hypertonic saline statistically does not influence the result of treatment. More research aimed at improving cerebral edema treatment is needed to identify new, effective forms of treatment.