• Journal of Korean Society on Water Environment
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• v.34 no.1
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• pp.1-9
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• 2018

In this study, the load of the river was calculated by using the actual data of the Yeong-bon C1, Yeong-bon C2, Yeong-bon C3 monitoring points of the Yeong-san river watershed to determine the excess. As a result, the BOD is 75.83 % at the Yeong-bon C1 and the five-year average value is higher than at other points. The Yeong-bon C3 was 72.15 % and Yeong-bon C2 was analyzed as 68.78 %. The five-year average of the T-P was 71.95 % for the Yeong-bon C2 and 69.86 % for the Yeong-bon C3 and 69.16 % for Yeong-bon C1; these levels exceeded the target water quality standards of 50 %. As a result of analyzing the pollutant load, we found that the Yeong-bon C1 has been highly affected by the nonpoint pollution source because the excess rate is high in the upper section of the flow rate. The Yeong-bon C2 showed a high excess rate in the lower part of the flow rate, and it was estimated that the influence of the point pollution source was large. The excess rate of the Yeong-bon C3 is small in the interval deviation, and it was evaluated as being affected by both point and non-point pollution sources. The TMDL monitoring network data were used to estimate the exceed ratio for the target water quality assessment, and the implementation evaluation was made by the flow exceedance probability interval to analyze the monitoring data so that the data could be utilized according to the purpose of the measurement network.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.81-94
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• 2007

In most experimental researches on the liquefaction phenomenon, an earthquake as a random vibration has been regraded as a sinusoidal wave or a triangular wave with an equivalent amplitude. Together with the development in the part of signal control and data acquisition, dynamic experimental equipments in the soil dynamics have also developed rapidly and further more, several real earthquakes have been simulated in the large model test such as shaking table tests and centrifuge tests. In Korea, several elementary laboratory tests to simulate the real earthquake load were performed. From these test results, it was reported that the sinusoidal wave cannot reliably reflect the soil dynamic behavior under the real earthquake motion. In this study, 4 types of dynamic motions such as the sinusoidal wave, the triangular wave, the incremental triangular wave and several real earthquake motions which were classified with shock-type and vibration-type were loaded to find something new to explain the change of the excess pore water pressure under the real earthquake load. Through the detailed investigation and comparison on all test results, it is found that the dynamic flow is generated by the soil plastic deformation and the velocity head of dynamic flow is changed the pressure head in the un-drained condition. It can be concluded that the change of the excess pore water pressure is related to the pressure head of dynamic flow. Lastly, a new hypothesis to explain such a liquefaction initiation phenomenon under the real earthquake load is also proposed and verified.

• Journal of Environmental Science International
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• v.26 no.4
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• pp.447-456
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• 2017

Chemical properties of aerosols were investigated by analyzing the inorganic water-soluble content in $PM_{2.5}$ collected in the downtown area of Jeju City in Jeju Island. Due to an increase in both the number of visiting tourists and the size of local population, the number of cars in this area is increasing, causing an increase in $PM_{2.5}$. Eight $PM_{2.5}$-bound major inorganic ions were analyzed during the summer and winter periods. The water-soluble inorganic component represents a significant fraction of $PM_{2.5}$. In particular, secondary inorganic aerosols contribute 36.2% and 47.5% of $PM_{2.5}$ mass in summer and winter, respectively. Nitrate concentrations increase for $[NH_4{^+}]/[SO_4{^{2-}}]$>1.5, and excess ammonium, which is necessary for ammonium nitrate formation, is linearly correlated with nitrate. These results are clearly observed during the winter because conditions are more conducive to the formation of ammonium nitrate. A significant negative correlation between Nitrogen Oxidation Ratio (NOR) and temperature was observed. The obtained results can be useful for a better understanding of the aerosol dynamics in the downtown area in Jeju City.

• Geotechnical Engineering
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• v.2 no.1
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• pp.15-26
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• 1986

Consolidated undrained standard triaxial tests for two remoulded clays and one undisturbed clay were carried out in order to find out the relationship between excess pore water pressure and axial strain in mortally consolidatated saturated clays during undrained shear. Tests were performed with isotropically-normally consolidated specimens by strain controlled and stress controlled loading. As the result of this stud!'a hyperbolic function expressing the relationship between pore water pressure and strain was found out, and it showed the same form as the Kondner's hyperbolic function for stress·strain behaviour. Two parameters used for the function can be obtained by CU-triaxial test.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.469-484
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• 2023

In this study, three types of structures-stepped gabion retaining walls, vertical gabion retaining walls, and parapets-were installed on the dam floor crest to prevent the overflow of deteriorative homogeneous reservoirs. The acceleration response, displacement behavior, and pore water pressure ratio behavior were compared and evaluated using shaking-table model tests. The experimental conditions were set to 0.154 g in consideration of the domestic standard and the seismic acceleration range according to the magnitude of the earthquake, and the input waveform was applied with Pohang, Gongen, and artificial earthquake waves. The acceleration response according to the design ground acceleration increased as the height of the embankment increased, and the observed value were larger in the range of 1.1 to 2.1 times the input acceleration for all structures. The horizontal and vertical displacements exhibited maximum values on the upstream slope, and the embankment was evaluated as stable and included within the allowable range for all waveforms. The settlement ratio considering the similarity law exhibited the least change in the case of the parapet structure. The amplification ratio was 1.1 to 1.5 times in all structures, with the largest observed in the dam crest. The maximum excess pore water pressure ratio was in the range of 0.010 - 0.021, and the liquefaction evaluation standard was within 1.0, which was considered very stable.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.2
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• pp.92-102
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• 2004

In this paper, an analytical solution of calculating the excess temperature field due to a point heat source is presented in the presence of spring-neap modulation of convective alongshore flow. The basic form of the solution is identical to that given by Jung et al. (2003) but the convective term in the exponential kernel function is extended and a spring-neap variation in the horizontal eddy diffusivity is newly introduced. A set of calculations have been performed to examine the sensitivity of the heat build-up to the change in current fields and turbulent dispersion. Results indicate that the excess temperature field is confined within the tidal excursion distance, while the excess temperature field beyond the distance is mainly controlled by the horizontal diffusion. The heat build-up within the distance is considerably affected by the spring-neap variation in the horizontal eddy diffusivity; the relatively high excess temperature more than 1$^{\circ}C$ is extended further when the eddy diffusivity has spring-neap modulation.

• The Korean Journal of Physiology
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• v.4 no.1
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• pp.47-54
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• 1970

The effects of excess salt ingestion or/and a prolonged electrical stimulation of the hypothalamus on the arterial blood pressure were studied in cats. The average mean arterial pressure determined in 12 control animals were $112.2{\pm}2.6\;mmHg$. In 15 animals in which 2% NaCl solution (2g/Kg of body wegight/day) was given for 20 days, average mean arterial pressure elevated to $147.7{\pm}6.1\;mmHg$. It was also found in four of them that salt-induced high blood pressure started to decline when salt solution was replaced by tap water. On the other hand, No change in average mean arterial pressure was observed in 10 animals, whose hypothalamus had been electrically stimulated for 28 days. In 11 animals in which the hypothalamus was stimulated with simultaneous excess salt ingestion for 20 days, there was a marked elevation in average mean arterial pressure which, however, does not significantly differ from that observed in excess salt ingested group. From the results obtained from the present experiment, it is concluded that 1) the hypertension is induced by an excess salt ingestion in cats, 2) the mean arterial pressure of cats is not affected at least by an increment of sympathetic tone for 4 weeks resulting from the electrical stimulation of posterior area of the hypothalamus, 3) in sodium·induced high blood pressure cats, four weeks of increment in sympathetic tone by the hypothalamic stimulation does not further elevate mean arterial pressure.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.275-279
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• 1977

During the experimental rearing period of common carp in a small simple recirculating aquarium combined with frequent exchanges of water and cleanings, some observations were made on the conditions of fish growing which was directly and instantly affected by the cleaning frequency of strainer, changing rate of water, division and frequency of feed supply, prohibition of excess feeding and the amount of dissolved oxygen. The fish don't seem to be stressed by the manipulation for the change of rearing water, cleaning of detritus in the strainer and filter. It appeared that the most hazzardous matters to fish growth were : 1) supplying feed when fish do not show active response to feed supplied, and 2) giving ample amount of feed at one time. When especially the amount of the feed is within the range fish instantly can swallow, the water clarity is maintained even after feeding operation, but if any excess amount is given the fish intake into mouth much more feed than able to instantly swallow and try to swallow it resulting in much dissolving and suspension of feed materials in water, making the water quite cloudy. Consequently all the water as well as filter bed becomes significantly polluted.

• Korean Journal of Ecology and Environment
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• v.49 no.1
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• pp.1-10
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• 2016

The increases of industrial and technological development and human activities have disturbed the balance of natural nitrogen (N) circulation. These phenomena have induced that large amounts of N are to be present in excess in air, soil and water environment. We investigated the effects of excess of reactive nitrogen ($N_r$) compounds on soil and water environment ecosystems through literature and case studies, and suggested the strategy of mitigating the acidification in soil and water ecosystems. $N_r$ moves to air, soil and water media, can be converted to different types, and interacts with other chemical compounds. As an efficient N management plan, the evaluation (application of monitoring and safety index) and the chemical restoration (research and development) of the acidification in soil and water environment ecosystems are required to minimize the effects of $N_r$ as well as policies to regulate the various emission sources and amounts of $N_r$.

• Environmental Analysis Health and Toxicology
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• v.12 no.3_4
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• pp.31-41
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• 1997

Public concerns about hazardous health effect from the exposure to organic by-products of the chlorination have been increased. There are numerous studies reporting that chlorination of drinking water produces numerous chlorinated organic by-products including THMs, HAAs, HANs. Some of these products are known to be animal carcinogens. The purpose of this study was to estimate health risk of DBPs by chlorinated drinking water ingestion in Seoul based on methodologies that have been developed for conducting risk assessment of complex-chemical-mixture. The drinking water sample was collected seperately at six water treatment plant in Seoul at March, April, 1996. In tap water of households in Seoul, DBPs were measured wilfh the mean value of 36.6 $\mu$g/L. Risk assessment processes,. which include processes for the estimation of human cancer potency using animal bioassay data and calculation of human exposure, entail uncertainties. In the exposure assessment process, exposure scenarios with various assumptions could affect the exposure amount and excess cancer risk. The reference dose of haloacetonitriles was estimated to be 0.0023 mg/kg/day by applying dibromoacetonitrile NOAEL and uncertainty factor to the mean concentration. In the first case, human excess cancer risk was estimated by the US EPA method used to set the MCL (maximum contaminant level). In the second and third case, the risk was estimated for multi-route exposure with and without adopting Monte-Carlo simulation, respectively. In the second case, exposure input parameters and cancer potencies used probability distributions, and in the third case, those values used point estimates (mean, and maximum or 95% upper-bound value). As a result, while the excess cancer risk estimated by US EPA method considering only direct ingestion tended to be underestimated, the risk which was estimated by considering multi-route exposure without Monte-Carlo simulation and then using the maximum or 95% upper-bound value as input parameters tended to be overestimated. In risk assessment for Trihalomethanes, considering multi-route exposure with adopting Monte-Carlo analysis seems to provide the most reasonable estimations.