• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.3-10
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• 2017

In case of Korea highways, about 60% of highways are paved by concrete and more than 50% of them were repaired due to reduction in required performance such as damage in pave or joint and delamination of cover pavement. However, repairing old material in such structure generally costs a lot of money and induces difficulty in maintenance. Thus, enhanced material for ensuring economic efficiency should be developed. The present study designed concrete mixtures with 3 levels of replacement using OPC (0, 10, 20%) in calcium aluminate cement and to evaluate material performance for load pavement, experimental works for setting time, compressive strength and flexural strength were carried out on those materials. As a result, 20% replacement for OPC was determined as an optimized material in terms of required physical performance and its unit price. Moreover, to determine cost in load pavement economy analysis using a program (CA4PRS) was conducted with widely used paving materials. Result showed that application for 20% replacement for OPC was the most efficient in economical aspect, arising from 4.052 and 1.577 billion won for total construction and user cost, respectively.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.3
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• pp.370-378
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• 2019

The hepatic ischemic model has recently been widely used for the epidemiological study of ischemic reperfusion injury. This study was carried out to investigate the protective effect of vanillin, which is known to have antioxidant and anti-inflammatory effects, against hepatic and renal injury using an ischemia-reperfusion rat model, and we also investigated the mechanism related to vanillins' protective effect. The test material was administered at a concentration of 100 mg/kg for 3 days, followed by ligation of the liver for 60 minutes to induce ischemia reperfusion. As control groups, there was a negative control, sham control and ischemia-reperfusion-only ischemia reperfusion control, and the controls groups were compared with the drug administration group. In the vanillin group, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were significantly inhibited compared with the AST and ALT activities of the ischemia-reperfusion group, and histopathological examination showed significant reduction of both inflammation and necrosis. The malondialdehyde (MDA) and superoxide dismutase (SOD) levels were significantly different from the ischemia-reperfusion group. In conclusion, vanillin showed a hepatocyte protective action by alleviating the cellular inflammation and cell necrosis caused by hepatic ischemia-reperfusion, and vanillin mitigated inflammatory changes in the kidney glomeruli and distal tubules. The protective effect is considered to be caused by vanillin's antioxidant function. Further studies such as on cell death and possibly vanillin's same effect on damaged tissue will be necessary for clinical applications such as organ transplantation.

• Journal of the Korean Geotechnical Society
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• v.35 no.7
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• pp.15-27
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• 2019

The purpose of this study is to investigate the mechanism about damages occurring at quay wall and backfill in Youngilman Port during Pohang earthquake (M5.4) on November 15, 2017. In the field investigation, the horizontal displacement of the caisson occurred between 5 cm and 15 cm, and the settlement at backfill occurred higher than 10 cm. 2D-effective Stress Analysis was performed to clarify the mechanism for the damage. The input earthquake motion used acceleration ($3.25m/s^2$) measured at bedrock of Pohang habor. Based on a numerical analysis, it was found that the effective stress decreased due to the increase of excess pore pressure in the backfill ground and the horizontal displacement of the caisson occurred by about 14 cm, and the settlement occurred by about 3 cm. In backfill, the settlements occurred between 6 cm and 9 cm. This is similar to field investigation results. Also, it was found that the backfill soil was close to the Mohr-Coulomb failure line due to the cyclic loading from the effective stress path and the stress-strain behavior. It may be related to decreasing of bearing capacity induced by the reduction of effective stress caused by the increase of the excess pore water pressure.

• The Korean Journal of Pharmacology
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• v.24 no.1
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• pp.53-61
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• 1988

The effect of antioxidants on the myocardial cellular damage which occurs during reoxygenation of hypoxic myocardium was examined in isolated rat hearts. The roles of oxygen free radical and lipid peroxidation in reoxygenation injury of myocardium were also investigated. In Langenorff preparation of isolated rat heart, which was made hypoxic by perfusion with the substrate free, hypoxic cardioplegic solution ($37^{\circ}C$, 90 min), the release of cytosolic enzymes (creatine phosphokinase, lactic dehydrogenase) and a lipid peroxidation product, malondialdehyde into the coronary effluent were abruptly increased by reoxygenation. The release of enzymes was closely parallel to that of MDA. These increases of enzymes and lipid peroxidation product were suppressed to various degrees in the presence of scavengers of superoxide anion (superoxide dismutase, 10,000 U), hydrogen peroxide (catalase, 25,000 U) and hydroxyl radical (dimethyl sulfoxide, 10%). A natural antioxidant, ${\alpha}-tocopherol$(4.5 uM) and a synthetic one, butylated hydroxytoluene (2 uM) suppressed the release of cytosolic enzymes with the concomittent reduction of lipid peroxidation as measured by malondialdehyde release into the coronary effluent. These effects of antioxidants were dose dependent, and were more pronounced when the antioxidants were administered throughout hypoxic and reoxygenation periods than given during reoxygenation period only. These results suggest that cytotoxic oxygen free radicals produced in the myocardium during reoxygenation may be responsible fur the myocardial cellular injury by enhancing the lipid peroxidation of cellular membranes. Furthermore, the antioxidants may exert protective effect against reoxygenation damage of hypoxic myocardium through the inhibition of lipid peroxidation reaction.

• The Korean Journal of Air & Space Law and Policy
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• v.20 no.1
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• pp.211-253
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• 2005

Recently, the Korean Supreme Court released two important decisions concerning damages for the pain and suffering from Aircraft noise. The local people who are living near the Air Force practice site at Maehyang-ri and the Kimpo International Airport brought lawsuits against the Korean government requesting damages for their financial loss from the severe noise and the damages for their pain and suffering. Plaintiffs alleged that they suffered physical malfunctions, extreme disturbances and the reduction of property values from the extreme noises which were daily repeated. District Court of Seoul Province did not allow plaintiffs all but the damages for pain and suffering. Plaintiffs could not prove the causation between their financial loss and the noise. The Supreme Court confirmed the lower court's decision. Article V of the National Compensation Act (analogous to the Federal Tort Claims Act of the USA) reads, "the government shall be liable for any loss caused by the defect on establishment or maintenance of public facilities." In the two cases, the major issue was whether the government's establishment or maintenance of Air Force practice site and the airport was defective because they caused serious noise to surrounding neighbors. Previously, the Supreme Court interpreted the clause "defect on establishment or maintenance of public facilities" as failure of duty to provide safety measures to the degree generally required to ordinary manager. However the Court at this time interpreted differently that the defect could be found if the facility caused to any person loss to the degree intolerable. In the two cases the Court confirmed the lower court's finding that noise level at the site was severe enough to be intolerable. This standard is based on the severity of the loss rather than the failure of duty. It became easier for plaintiffs to prove the cause of action under this interpretation. The consequence of the ruling of these two cases is 'rush to the courtroom' by the local people at similar situations. The ruling of these two cases was not appropriate both in theory and in consequence. The Korean tort system is basically based on the theory of negligence. Strict liability is exceptional only when there is special legislation. The Court created strict liability rule by interpreting the Art. V of the National Compensation Act. This is against the proper role of the court. The result of the cases is also dismal. The government was already sued by a number of local people for damages. Especially the Department of Defense which is operating many airports nationwide has financial hardship, which will cause downsizing military practice by the Air Force in the long run, This is no good to anyone. Tens of millions of dollars which might be used for compensation might be better used to prevent further noise problem surrounding airports.

• Journal of Life Science
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• v.19 no.4
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• pp.442-448
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• 2009

We investigated photooxidation and responses of antioxidant enzymes involved in scavenging reactive oxygen species (ROS) after light-chilling ($4^{\circ}C$) for 2 days and post chilling ($25^{\circ}C$) in rice leaves. Chilling leaves indicated a 50% reduction in photosynthetic efficiency ($F_v/F_m$ ratio) and a 48% increase of $H_2O_2$, respectively, compared to the control group. In comparison with the control, activities of superoxide dismutase (SOD) and glutathione reductase (GR) increased at light-chilling and post-chilling. CuZn-SOD and Mn-SOD among SOD forms were detected in rice leaves, while Fe-SOD was not found. The increase of SOD and GR activity may serve as a basis for defense against chilling injury as it dismutase superoxide generated by light-chilling. Catalase (CAT) activity decreased during light-chilling, while activity of APX showed remarkable increase during light-chilling in rice leaves. Among CAT isoforms analyzed by 10% native PAGE, activities of isoform -2 and -3 were inhibited during light-chilling. From the elevated APX activity and decreased CAT activity, we suggest that these two enzymes show mutual supplementary relationships, indicating different tendency during light-chilling.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.97-104
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• 2020

The present study conducted mock-up tests under the simulated sewage environments to examine the practical significance and limitation of coating materials that were previously developed on the basis of the bacterial glycocalix as a protection of concrete structures exposed to microbiological and sulphate attacks. The variations of the compressive strength and mass of the concrete due to the sulphate attack were measured using cylinder specimens. The bacteria growth and glycocalix formulation were calculated from the samples extracted from the sewage pipes. The next generation sequencing analysis was also conducted for environmental damage assessment due to the use of Rhodobacter capsulatus in the simulated sewage environments. The mock-up tests revealed that the developed coating materials have a good potential in resisting the sulphate attack, indicating no reduction on compressive strength and mass of the coated concrete under the sewage environment. At the age of 91 days, the concentrations of viable bacteria and glycocalix measured from the hardened coating materials were 1.4×10⁴cell/mL and 67.5mg/㎤, respectively. Moreover, harmful strains were not observed in the sewage water including glycocalix-coated concrete pipes. This implies that Rhodobacter capsulatus used in the coating materials does not influence negatively the microorganism cluster in the sewage environments.

• The Journal of Engineering Geology
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• v.12 no.1
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• pp.53-61
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• 2002

Cut-slope due to the road construction is one of the most significant problems in the domestic case, that is, 70% of the land is covered by mountain. Moreover, typhoons or heavy rains concentrated in summer season causes the failure of cut-slope. Rock-fall and soil slope failure take 40.8% and 29.5% out of the entire domestic cut-slope failure, respectively. Rock-fall is quickly occurred by the free fall or rolling of rock fragments generally in the upper slope. Soil slope failure produces a clastics-flow and increases casualty especially when caused by heave rainfall because the velocity of the movement is verb high. Considering the car speed and rock-fall velocity, it will take a life in a moment. This study analyzes a set of field data of most recently collapsed domestic road cut-slopes to characterize these cut-slopes and the nature of rock-falls and clastics flows at each site. Based on the results, design criteria for a road alarm system are proposed, considering the relationship between the time required for clastics-flow and the velocity and braking distance of a cat at the incidence. The road alarm system proposed herein would operate instantly after a rock-fall and it will minimize damages, by warning drivels approaching to the collapse or collapsing location in advance.

• Journal of Korea Water Resources Association
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• v.42 no.4
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• pp.319-329
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• 2009

Sediment release openings or pipes are installed in the flood control dam constructed to reduce flood damages, which are to allow water and sediments pass through the dam and to prevent flow blockage and sedimentation in the upstream area of the dam. The Hantan River Flood Control Dam (HRFCD) has been projected for flood damage reduction and sediment release openings and ecological passages are considered for the dam design. In this study, sediment deposition due to the construction of HRFCD was analyzed using the HEC-6 model and compared with the state before the dam construction with respect to the conditions of the annual mean daily discharge and annual discharge hydrograph. According to the numerical results, although downstream water levels were changed by the dam structure, the effects of bed changes were not propagated from the dam over 2 km upstream. Also, 2D numerical models of RMA2 and SED2D were used to predict bed changes in the upstream area with and without sediment release openings. Consequently, it is presented that sediment release openings decreased maximum deposition height in the upstream channel of the dam.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.667-673
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• 2010

The near fault ground motion (NFGM) is characterized by a single long period velocity pulse with large magnitude. NFGMs have been observed in recent strong earthquakes, Northridge (1994), Japan Kobe (1995), Turkey Izmit (1999), China Sichuan (2008), Haiti (2010) etc. These strong earthquakes have caused considerable damage to infrastructures because the epicenter was close to the urban area, called as NFGM. Extensive research for the far field ground motion (FFGM) have been carried out in strong seismic region, but limited research have been done for NFGM in low or moderate seismic regions because of very few records. The purpose of this research is to investigate and analyze the seismic response of reinforced concrete bridge piers subjected to near-fault ground motions. The seismic performance of six RC bridge piers depending on three confinement steel ratios and three superstructure mass was investigated on the shaking table. From these experimental results, it was confirmed that the reduction of seismic performance was observed for test specimens with lower confinement steel ratio or more deck weight. The displacement ductility of RC bridge piers in terms of the stiffness degradation is proposed based on test results the shaking table.