• Journal of Korea Water Resources Association
• /
• v.46 no.11
• /
• pp.1069-1078
• /
• 2013

The Bangudae Petroglyphs, national treasure No. 285 is located within submerged upper districts of Sayeon dam supplying the main residential water in Ulsan. Of the many ways for the reservation of Petroglyphs located the altitude at 53~57 m, the plan that we take it out of the water lowering the water level from 60 m to 52 m has been examined mainly in case of controlling artificially the water level of the dam. In this paper, we examined expected problems from the loss of dam function and the change of water quality from water deterioration caused by the water level control of the Sayeon dam. Using the model of Vollenweider and CSTR (Continuous Stirred Tank Reactor), we analyzed the density change of BOD and COD, representative water quality index and the TP and TN, the main reason of algae growth. The result showed that the density of COD lowered a little but the density of TP and TN went up over 130% when controlling the water level from 60 m to 52 m. These changes cause a serious algae problem and if doing the water quality management as the density of TN and TP, the water quality would become worse. Water storage and supply residential water decreases, and the water quality becomes worse because of eutrophic state.

• Journal of the Korean Society of Industry Convergence
• /
• v.20 no.4
• /
• pp.257-263
• /
• 2017

The following thesis researched into the characteristics of electrolytic ion water with different levels of electrical conductivity by adding NaCl into tap water which is for experimental use in multi-layered electrolytic ion water generator. Electrolytic ion water is generated by underwater electrolysis and the electrolysis generator has a simple structure, is easy to control and is highly utilized in industries. Electrolytic ion water is useful in many areas since it has a superior sterilizing power, has no possibility of secondary pollution itself as water and removes active oxygen. In the experiment, we used tap water with NaCl excluded and water with three different levels of electrical conductivity by changing NaCl concentration levels into three levels. The features of current and voltage in electrolytic ion water represented a form of quadric instead of the linear characteristic following ohm's law. As well, as the electric conductivity of water and applied voltage increased, we were able to generate much stronger acid water and alkali water.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.5
• /
• pp.707-717
• /
• 2011

Replacement of old water distribution pipes for protecting water quality induced by pipe corrosion requires enormous budget. Even after the replacement, however, corrosion can occur again at any times and, therefore, inhibitive measure of the corrosion will be not only economical but needed to diminish the consumers' distrust on tap water quality. In 2008, National Environmental Research Institute did a survey on 8 major drinking water source and proposed to establish the Langelier Saturation Index(LI) as a corrosion index in Drinking Water Quality Criteria. Among the water industries of Korea, K-Water is the only one that set up the level of pH over 7.0 and LI above -1.5 on yearly average basis. However, no systematic regulation including LI to inhibit the corrosive tendency has been established yet. In this paper, LI values out of 31 drinking water treatment plants were analyzed and two-stage control of LI value as a measure of corrosive tendency of water is proposed. Primarily, water treatment facilities may operate the system at a target LI value below -1.5. Following the investigation on the effect caused by adjusting the LI value on water quality and corrosiveness, it will be desirable to improve LI value below -1.0 in the long run. In addition to the LI, supplemental use of Larson's modified ratio (LMR) which incorporates hydraulic detention time will be necessary. Several methods to prove the inhibitive effect of improving the LI value on water quality have been also suggested.

• Journal of Bio-Environment Control
• /
• v.7 no.3
• /
• pp.237-245
• /
• 1998

Greenhouse crop production under critical summer climate In Korea has considerable difficulties because of high temperature and relative humidity. In this study, some water pipes were tested as a means of the dehumidification and increment of evaporative cooling efficiency. As a result of heat transfer characteristic analysis, overall heat transfer coefficient of copper pipe was larger than steel pipe, and estimated values were smaller than measured values. The condensed quantities of vapor were not significantly different between copper pipe and steel pipe, however dehumidifying effect by the water pipes was significantly large. It was estimated based on the results that the evaporative cooling system by the water pipe will be able to increase the evaporative cooling efficiency of about 48%, and decrease the temperature of about 1.3$^{\circ}C$.

• Korean Journal of Weed Science
• /
• v.11 no.3
• /
• pp.159-166
• /
• 1991

Seven oxyfluorfen formulations were tested for control of 8 weed species and rice injury under four different water depths with various ages of rice seedlings. Among formulations tested, rice injury was slight by formulations of Elvan, Coal Slag, Chitosan and Bentonite B under 0 cm or shallow water depths, and by those of Elvan and Coal Slag under deep water conditions. Weed control was high by Bentonite A and B, and Chitosan, and was low by Elvan. Coal Slag and Sand coated oxyfluorfen, if the target weeds of oxyfluorfen are annual species, further development of Elvan, coal slag, chitosan and Bentonite A would be controlled to increase control efficacy or to decrease rice injury.

• Journal of Bio-Environment Control
• /
• v.16 no.4
• /
• pp.333-337
• /
• 2007

This study was conducted to assess effects of soil moisture condition and ventilation on development of fermented fruit of oriental melon. In higher soil moisture condition (-10 kPa), roots absorbed more water and transpiration was decreased under low temperature and high humidity conditions. Development of fermented fruit may be come from absorbed water concentrated placenta with higher soluble solid. Fermented fruit was developed with higher level at Shintozoa and Elite, was developed with lower level at Hongtozoa, and was not developed at self-rooting of oriental melon. Ventilation on fruit did not affect development of fermented fruit at Shintozoa, Elite, Hongtozoa and self-rooting seedling. Ca contents of flesh and placenta of fruit under ventilation treatment were higher than control but contents of Acetaldehyde, Ethanol and Ethylacetate were lower.

• Journal of Environmental Impact Assessment
• /
• v.23 no.3
• /
• pp.197-207
• /
• 2014

In this study, the functional priority of wetlands was determined through analysis of previous research. To determine relative importance, three processes were performed. First, quantitative values from the case studies were normalized. Second, non-quantitative values were prioritized based on standard criteria. Third, equal weight was applied as long as there was no special consideration regarding a particular value's disproportionate priority in the research. Finally, results were grouped into large, medium, and small classes.In this study, the functions of the medium class were found to be the most significant, in the following order of priority: water supply and ground water recharge; culture and recreation; biodiversity; product; water quality control; flood control; erosion control; moderation of climate change; and provision of biochemical matter. To verify these results, we compared our findings with those of an assessment that used the Rapid Assessment Method (RAM) on the same type of study area. Whereas this comparison indicated some correlations by the culture, water storage, and genetic sustainability functions, it suggested a lack of such relationship by the water purification and flood prevention functions.

• Journal of Korea Water Resources Association
• /
• v.49 no.1
• /
• pp.51-60
• /
• 2016

The purpose of this study is to examine the control function of discharged flow due to the shape and plane arrangement of permeable submerged breakwater. For the discussion on it in detail, 3-dimensional numerical model based on PBM (Porous Body Model), which is able to simulate directly interaction of Fluid Permeable structure Seabed has been used to simulate water discharge in a NWT (Numerical Water Tank). To verify the applicability, LES-WASS-3D is analyzed comparing to the experimental result about propagation characteristics of dam-break wave through a permeable structure. Using the results obtained from numerical simulation, the effects of the shape and plane arrangement of submerged breakwater on reducing velocity and flow induction have been discussed related to the mean flow distribution and vertical distributions of horizontal velocities around ones.

• Korean Journal Plant Pathology
• /
• v.14 no.6
• /
• pp.578-582
• /
• 1998

In greenhouse studies, control efficacy of water chestnut (Eleocharis Kuroguwai) by Epicoccosorus nematosporus was affected by temperature and dew condition. The appressoria were formed abundantly in the range of 20~28$^{\circ}C$. When stem segments o(30 cm long) of the water chestnut were inoculated with the conidial suspension of E. nematorporus, the mean conidial number attacted amounted to 2,545 conidia. Out of 2545 conidia attacted to the stem pieces, 1,733 (68%) conidia formed appressoria. When these stem pieces were treated for 24 hr at 28$^{\circ}C$ under dew condition, 183,1 (7.2%) lesions were formed 10 days after incubation. The time necessary for the death of the plants was about 24 days. Appressoria were formed at 15~35$^{\circ}C$, but decreased rapidly in their numbers at the temperature lower than 1$0^{\circ}C$ or at 35$^{\circ}C$. The appressoria formation seemed to be depended on the dew duration, which was effective to the lesion formation and plant mortality. Under dew duration of 16~24 hr with temperature range of $25^{\circ}C$ to 3$0^{\circ}C$, the weed control was increased up to 93.9%. There were no differences between the first and second or third dew treatments. A delay of 2 or 3 days in dew treatment did not increase the mortality of plants. For the use of E. nematosporus as a mycoherbicide of water chestnut, a conidial suspension should be applied when dew conditions are kept for 12 hr after inoculation.

• Journal of Animal Environmental Science
• /
• v.7 no.3
• /
• pp.191-195
• /
• 2001

This research was carried out to investigate the effect of ozone treatment to improve the livestock drinking water quality. Ozone concentration treated was 18.5~36.5ppm in each system. PH and dissolved oxygen(DO) concentration in drinking water was increased by ozone and ozone+anion treatment. But there was no difference in UV used for drinking water treatment. Oxidation and deduction Potential(ORP) was increased while ozone was treated. Colony Forming Unit(CFU) of E. coli 0.8:$H^-$, Salmonella typhimurium, Staphylococcus aureus was decreased after 30 minute to 1 hour ozone and UV treatment.