• Geomechanics and Engineering
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• v.28 no.6
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• pp.573-584
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• 2022

Water inrush may occur during seaside urban tunnel excavation. Various factors affect the water inrush, and the water inrush mechanism is complex. In this study, nine evaluation indices having potential effects on water inrush were analysed. Specifically, the geographic and geomorphic conditions, unfavourable geology, distance from the tunnel to sea, strength of the surrounding rock, groundwater level, tidal action, cyclical footage, grouting pressure, and grouting reinforced region were analysed. Furthermore, a two-step interval risk assessment method for water inrush management during seaside urban tunnel excavation was developed by a multi-index system and interval risk assessment comprised of an interval analytic hierarchy process, fuzzy comprehensive evaluation, and relative superiority analysis. The novel assessment method was applied to the Haicang Tunnel successfully. A preliminary interval risk assessment method for water inrush was performed based on engineering geological conditions. As a result, the risk level fell into a risk level IV, which represents a section with high risk. Subsequently, a secondary interval risk assessment method was performed based on engineering geological conditions and construction conditions. The risk level of water inrush is reduced to a risk level II. The results agreed with the current tunnel situation, which verified the reliability of this approach.

• Journal of Korea Soil Environment Society
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• v.5 no.3
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• pp.25-33
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• 2001

The study was performed to examine the influence of sea tide on a tideland composition by Saemankeum reclamation and to evaluate a correlation between the characteristics of physical and the pollution level of heavy metals. Also, it was investigated the characteristics of heavy metal adsorption through a batch experiment and applied to adsorption isotherm equations. In the results, the flow of sea tide occurred to accumulation action and had an effect on the content of heavy metals. It suggests that influence factors for the content of heavy metals in the tidal flat be grain size, cation exchange capacity and organic matter content. Adsorption capacity of heavy metals occurs to 90% adsorption rate for injection concentration within 30 minutes. The flow patterns in Saemankeum area will undergo a change for soil size distribution. In result, this soil size changed will effect the adsorption capacity of heavy metals.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.3
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• pp.140-148
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• 2014

A storm surge barrier is a specific type of floodgate, designed to prevent a storm surge or spring tide from flooding the protected area behind the barrier. A surge barrier is almost always part of a larger flood protection system consisting of floodwalls, dikes, and other constructions. Surge barriers allow water to pass under normal circumstances but, when a (storm) surge is expected, the barrier can be closed. Among the various means of closing, buoyant flap typed storm surge barrier which was indicated by MOSE project in Italy is chosen for Masan bay protection, and the motion of the surge barrier under the action of storm surge and wave is examined using FLOW-3D, a computational fluid dynamics software analyzing various physical flow processes. Numerical result shows that storm surge barrier is successfully operated under wave height 3 m, and tidal range 2 m.

• Biomolecules & Therapeutics
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• v.11 no.1
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• pp.41-50
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• 2003

General pharmacological properties of DA-8159, a new pyrazolopyrimidinone derivative were examined in laboratory animals to investigate its safety profile. The oral administration of DA-8159 (1, 5 or 30 mg/kg) in mice and rats had no effect on general behaviors and central nervous system of the animals in test systems, such as hexobarbital-induced sleeping time, motor coordination, normal body temperature, writhing syndromes induced by 0.75% acetic acid solution, chemo-shock produced by pentetrazole solution and rotar rod test. Anesthetized cats treated intravenously with DA-8159 (0.1, 0.3, 1, 3 or 10 mg/kg) showed transient and mild decrease in blood pressure. However, heart rate, respiration rate and tidal volume were not changed by intravenous DA-8159. In the isolated organs including ileum, heart (sinus rate of atria and contractility of papillary muscle), trachea of guinea pigs and phrenic nerve of rats, DA-8159 ($10^{-8}$ ∼$10^{-5}$ mg/L) did not elicit any effect or inhibitory action on the chemically or electrically stimulated contraction. DA-8159 did not influence gastric secretion, pH and total acid output in rats and intestinal propulsion in mice. The administration of DA-8159 in rats had no effect on the platelet aggregation induced by ADP in rabbit plasma, urinary volume and electrolyte ion ($Na^{+}$, $K^{+}$, $Cl^{-}$) excretion in rats. Prothrombin time (PT) of the rats showed a mild but significant increase after administration of DA-8159. Activated partial thromboplastin time (APTT), however, was not affected by DA-8159. These results indicate that DA-8159 does not exert any of serious pharmacological effects.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.599-609
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• 2017

Desalination plants have been recently constructed in many parts of the world due to water scarcity caused by population growth, industrialization and climate change. Most seawater desalination plants are designed with a submarine pipeline for intake and discharge. Submarine pipelines are installed directly on the bottom of the water body if the bottom is sandy and flat. Intake is located on a low-energy shoreline with minimal exposure to beach erosion, heavy storms, typhoons, tsunamis, or strong underwater currents. Typically, HDPE (High Density Polyethylene) pipes are used in such a configuration. Submarine pipelines cause many problems when they are not properly designed; HDPE pipelines can be floated or exposed to strong currents and wind or tidal action. This study examines the optimal design method for the trench depth of pipeline, analysis of on-bottom stability and dilution of the concentrate based on the desalination plant conducted at the Pacific coast of Peru, Chilca. As a result of this study, the submarine pipeline should be trenched at least below 1.8 m. The same direction of pipeline with the main wind is a key factor to achieve economic stability. The concentrate should be discharged as much as high position to yield high dilution rate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.1
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• pp.34-40
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• 1999

Models of beach response due to sea level rise were verified by experiments and potential shoreline retreat around Korea and Japan was predicted. Wave tank experiments demonstrated that not only static retreat by water level rise but also additional retreat by wave action plays an important role in total retreat and additional retreat becomes important on the condition of high waves. The result of long-term analysis of tidal data over past 3 decades shows the tendency toward rise by an average of 1.79 mm/year, which is the result of rise in 29 regions and fall in 12 regions. Based on analyzed rate of long-term sea-level rise, potential shoreline retreats of study area after 50 years were calculated and the result shows serious loss of beach.

• Geophysics and Geophysical Exploration
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• v.3 no.1
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• pp.1-6
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• 2000

The 1 $km^2$ area studied is located in Sukchun-ri, Hwasung-koon, the southern part of Kyeonggi-do. Even though this site has been known as a contaminated area caused by seawater intrusions, geophysical and geochemical surveys have never been carried out at the site to determine the extent of the seawater contamination and to investigate whether the seawater intrusion is in progress. The purpose of this study is to determine the extent of seawater contamination and a preferred channel of the seawater intrusion using geophysical methods such as DC resistivity surveys with Schlumberger array and a dipole-dipole array. In order to determine whether the seawater intrusion is in progress in the area, DC resistivity monitoring with Schlumberger array was performed. According to the resistivity map obtained from the inversion of the resistivity data measured with Schlumberger array, the study area is divided into two districts as relatively lowly resistive (less than 30 ohm-m) and highly resistive (more than 30 ohm-m) areas. The distribution of the lowly resistive area is consistent with the distribution of the layer composed of clay minerals, and the resistivity of this layer decreases slowly as approaching to the old seashore. Hydrogeological analysis shows that the clay layer within a distance of about 200 m from the seashore has been already contaminated by sea-water and its electric conductivity is 8 times higher than that of the sand layer covered by the clay layer. According to the results of the 2-dimensional DC resistivity surveys with a dipole-dipole array, there are two preferred channels of the seawater intrusion in the site, and both the channels are in the NW-SE direction from the old seashore. The lowly resistive zone in the southern channel extends to a depth of 80 m. The DC resistivity monitoring with Schlumberger array was carried out along the preferred channel which has the low resistivity Bone (fracture zone) that extended to a depth of 80 m. The time series of apparent resistivity, measured at a distance of 260 m from the old coast line, fluctuates with a period of 12 hours. From these observations, it can be concluded that the seawater intrusion caused by tidal action is still in progress along the fractured zone interpreted by the DC resistivity surveys with a dipole-dipole array.

• Journal of Wetlands Research
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• v.21 no.2
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• pp.102-113
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• 2019

Slack-tide sampling was carried out at 6 stations at high and low tide for a tidal cycle during spring tide of the early summer (June) and summer (July, August) of 2016 to determine the difference of water quality according to tide in Masan Bay, Korea. The mixing regime of all the water quality components investigated was well explained through the correlation with SAL. In the early summer and summer, TURB, DSi and NNN which mainly flow into the bay from the streams and SS, COD, AMN and $H_2S$ which mainly indicate the internal sink and source materials have a property of conservative mixing and non-conservative mixing, respectively. The conservative mixing showed a good linear relationship of the water quality between high and low tide, and the non-conservative mixing showed a variation of different pattern each other. Factor analysis performed on the concentration difference data sets between high and low tide helped in identifying the principal latent variables for them. In early summer, multiple effects (tidal action, natural influx and internal sinks and sources etc.) acted in combination for the differences to be distributed evenly in four factors (VF1~4), since there were few allochthonous inputs as a low-water season. On the contrary, in summer, the parameters showing large concentration difference at ST-1 affected by stream water were concentrated in one factor (VF1) and clearly distinguished from the parameters affected by the internal sinks and sources. In fact, there is no estuary (bay) that always maintains steady state flow conditions. The mixing regime of an estuary might be changed at any time due to the change of flushing time, and furthermore the change of end-member conditions due to the internal sinks and sources makes the occurrence of concentration difference inevitable. Therefore, when investigating the water quality of the estuary, it is necessary to take a sampling method considering the tide to obtain average water quality data.

• Journal of the Korean earth science society
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• v.36 no.3
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• pp.222-235
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• 2015

Samples were collected from both places including the coastal area within the height of 5 m above the mean sea level (msl) (DH) and the top of the coastal terrace of 10-15 m msl (KS) high in Gwangseungri, Gochanggun, Korea. To find the origin of the deposit in the coastal area, granulometric analysis and geochemical analysis were performed. The result showed that the DH samples were originated from the reddish soils overlaying weathered bedrock which presented gradual change of chemical composition from the bottom toward the top. Clay minerals were found from the DH samples. These results concluded that the DH samples were found as in-situ weathered materials. The KS samples were originated from the soil layer covering gravel layer at the foot slope of the hill along the coast. The KS samples contained different chemical compositions from the DH. It is inferred that some of this layer was disturbed or experienced the influx of foreign material. The particle size of the KS samples was different from those found on the beach. The particle size of lower parts of KS site was finer than that on the beach, but the particle size of middle part of the site was coarser than that on the beach. The sorting of the KS site was poorer than that on the beach. Thus, it is inferred that some parts of the layer were formed by short-lived high energy event rather than sustained and continuous action of tidal currents and/or waves. Analysis using an optically stimulated luminescence (OSL) method showed that the burial age of samples from KS site were found 0.65-0.71 ka. Though the characteristics of the sediment layer and forming event in this area should be further studied, it can be inferred that this sedimentary layer formed by coastal flooding with storm.

• Korean Journal of Veterinary Research
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• v.47 no.1
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• pp.103-115
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• 2007

The aim of this study was to compare the reaction of the cardiovascular system, and the anesthetic effect among 3 experimental groups, epidural administration of medetomidine as a single agent, the combination of buprenorphine and medetomidine, and the combination of fentanyl and medetomidine. Twenty one dogs were anesthetized with isoflurane and allowed to breathe spontaneously. Epidural, arterial, and venous catheters were inserted. The tip of epidural catheter was positioned at the level of the space between the sixth and seventh lumbar vertebra. After a stable plane of anesthesia was achieved, these dogs were each administered one of the following treatments epidurally : medetomidine $10{\mu}g/kg$ (Group M), a combination of medetomidine $5{\mu}g/kg$ and buprenorphine $10{\mu}g/kg$ (Group M/B), and a combination of medetomidine $5{\mu}g/kg$ and fentanyl $10{\mu}g/kg$ (Group M/F). Heart rate (HR), Respiratory rate (RR), End-tidal carbon dioxide (EtCO2), and arterial blood pressure were measured before drug administration (base line) and 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 min postinjection. Blood gas analysis was performed before injection and 5, 15, 25, 35, 45, 60 min postinjection. Isoflurane was discontinued 80 min postinjection and pain/motor function were evaluated up to 260 min postinjection every 15 min. At the early stage of drug introduction (until 5 min), the HR was decreased significantly in all 3 groups compared with base line. In Group M, HR was significantly decreased compared with the other 2 groups. With time (starting 20 min after drug introduction), the HR was decreased significantly in Group M/B in respect to base line. However, no significant difference was seen number-wise in all 3 groups. During 60 min after drug introduction, the systolic, diastolic and mean arterial pressures were highest in Group M and lowest in Group M/F. Among 3 groups, drug action and motor loss duration were longest in Group M/F. Analgesic effect observed in the M/F group was the most prominent and long-lasting, compared to those seen in the other 2 groups. Given the fact that the recovery of motor function takes place in a short period of time after analgesic effects disappeared, additional use of M/F depending on the patient's condition would be a good way to achieve effective pain management. However, proper care should be taken to ensure the function of cardiovascular system in the patient because the administration of M/F under isoflurane anesthesia results in a significant decline in arterial blood pressure ($65{\pm}10mmHg$).