• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.283-290
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• 2008

The repair technique using surface impregnation of reactive compound is so effective for deteriorated concrete structures that many researches are recently focused on these works. Particularly, inorganic impregnant is regarded as ecofriendly material because there is no air-pollution during manufacturing process as well as field coating works. Furthermore, The delamination between old concrete and impregnated surface does not occur, resulting from different material characteristics. In order to evaluate the durability performance of surface-impregnated concrete, durability evaluation through the long-term exposure tests is significant, however, experiments are usually limited to the temporary and qualitative laboratorial scope. In this study, durability characteristics for inorganic and organic/inorganic impregnated concrete specimens are evaluated through longterm chloride exposure test. The specimens with 21MPa and 34MPa strength have been prepared and exposed to chloride attack in the atmospheric, tidal, and submerged conditions. Evaluation for compressive strength, chloride penetration, and electrical potential (half cell potential) for steel corrosion are performed for the specimens exposed for 2 years. From the results, no distinct strength gaining is observed but the resistance to chloride penetration and steel corrosion is evaluated to be improved through surface impregnation. The more improved resistance to chloride attack is measured in the inorganic impregnated concrete and the results from atmospheric condition show more improved resistance to chloride attack than those from submerged and tidal condition.

• Journal of Korea Water Resources Association
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• v.41 no.10
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• pp.983-993
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• 2008

In recent times, sea level increasing caused by abnormal weather and global warming, sea-sand dredging and complex development causes various kind of erosion damages onto the coastal area in the world. The various types of erosion control and protection methods are applied but there are no signs of fruitful effectiveness. The PC concrete protection block for shore protection structure is practically installed in globally but most of structures in the present day became villainous because of bad accessability. In this study, hydrophilic revetments for control and protection of coastline erosion will be developed in order to make up for a faculty of the shore erosion protection block with better accessibility and excellent protection ability. Experimental measurements were researched to insure for the capacity and facility on reflection coefficient, overtopping volume, and overtopping height characteristics of newly developed shore erosion protection block in model tests. As the result, hydraulic model tests show much excellent than the general step block. Field tests were carried out also to verify through vegetative test on an affinity and construction work test of control-protection on coastline erosion with actual utilization. In the latter case, deposition of sand accumulation occurred in fairly short time at the established reaches and then we can be confirmed to utilize for newly developed block as the revetments for control and protection of coastline erosion.

• The Journal of Engineering Geology
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• v.17 no.3
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• pp.435-443
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• 2007

This study shows the prediction of the engineering properties of weathered zone bearing corestones through the engineering geological surveys and the scale model test in the laboratory. The window survey and the observation on the borehole core were peformed on three natural slopes in corestones area in order to analyse the distribution pattern and the geometrical properties of corestones. Natural corestones were crushed and abrased for the scale model test into less than 5 mm in maximum-2mm in average by the scale reduction ratio based on the size of natural corestones and the specimen size. Scale model tests were carried out on soil and plaster model specimens with different corestone content ratio - 0%, 10%, 20%. The direct shear test on soils shows that shear strength is increased by the increase of corestone content ratio. The increase of cohesion is, however, more important factor to the shear strength of soil for 20% corestone content ratio due to interlocking of crushed corestone particles. The plaster model test shows a tendance of increase of UCS and modulus of elasticity with increase of corestone content. The variation ratio of specimen property by change of corestone content ratio in plaster model test was applied to in situ properties in order to estimate the properties of weathered zone bearing corestones. So it could be predicted that the increase of corestone content to 10% and to 20% produce about 18% and 30% UCS's increase respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.765-773
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• 2018

The purpose of this study was to investigate the effect of Healing Beat on autonomic balance, heart rate, and anxiety in healthy adults exposed to stressors. Data were collected from 64 healthy volunteers who volunteered after responded to a recruitment announcement at D City University and analyzed using descriptive statistics, the X2-test, the t-test, and repeated measures of ANOVA. Results showed that both experimental and control general characteristics and variables were homogeneous. Significant intergroup differences were obtained for autonomic balance (F = 6.151, p <.001), heart rate (F = 5.455, p <.001), and anxiety (t = -7.633, p <.001). These results indicate Healing Beat is effective at relieving anxiety in stressful situations, and that Healing Beat can be used to relieve stress in many clinical situations or daily life when individuals are exposed to various stressors.

• Korean Journal of Ecology and Environment
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• v.53 no.2
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• pp.165-172
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• 2020

Heavy metals are common pollutants in the freshwater environment and have toxicological effect in habitat organisms. The heavy metals highly accumulated in sediment and organism, and observed various physiological responses. In this study, we investigated the molecular response to heavy metal toxicity (Al, Aluminum; Cr, Chromium; Cu, copper; Mn, Manganese; Zn, Zinc) through expression of heat shock protein 40, 70, 90 (HSP40, 70, 90), cytochrome 450 (CYP450), Glutathione S-transferase (GST) and Serine-type endopeptidase (SP). HSPs showed up-regulation in Cu and Zn exposures. Furthermore, HSPs expression in treated groups tended to be higher than the control group. The tendency of CYP450 and GST mRNA expression was higher for Cr and Cu than for other exposure group. The expression of SP gene was low at Al exposure and other group were measured to be similar to control. These results suggest that heavy metal toxicity in freshwater ecosystem may affect physiological and molecular process. Also, the comprehensive gene expression in the aquatic midge Chironomus riparius give useful information to potential molecular biomarkers for assessing heavy metal toxicity.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.2
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• pp.25-32
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• 2000

Fire-resistant boom is one of the most important facilities in in situ homing of spilled oil. Thermal response of a fire-resistant boom to turning is experimentally investigated in this paper by using an electric furnace and a burning test facility. This test facility is composed of a test tank, a fire boom, a hood for inhaling smoke, an incinerator for burning up gases and thermocouples, etc. Thereby a systematic method of approach in small laboratory scale is developed to study the performance of a fire-resistant boom. Burning test is carried out for the fire boom model which has been developed through the present study. It is shown that the present fire boom model has capability to withstand the high temperature around 800℃ and high rate of heat flux on it due to homing. For more realistic experimental environments, larger dimensions in devices and longer time in experiments are recommended in near future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.3
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• pp.217-224
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• 2004

In 1980's, the concrete bridge decks were constructed with 4cm wearing surface layer instead of asphalt concrete overlays. After about 15 year service periods, deteriorations were appeared on the surfaces of highway bridge decks. Various field NDTs and lab tests were done to analysis the cause of the deterioration on the concrete deck surface. The main cause was the corrosion of rebars with thinner concrete top cover than the design value. The rebars with thinner concrete top cover was earlier corroded by penetrated chloride ions. If the appropriate top cover could be achieved, the bare concrete bridge decks can be used without earlier deteriorations.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.511-523
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• 2002

In order to develop the weir with high reaeration efficiency, the reaeration experiments at linear weir, ogee spillway type weir, and labyrinth weirs were conducted and the results were compared. The effect of roughened crest was also analyzed. It was found from the experiments that the oxygen transfer efficiency at the ogee spillway type weir was the lowest and that at the linear weir was second lowest among the weirs used in the experiments. It was also revealed that the reaeration efficiencies of the labyrinth weirs increase as the included angles become smaller. The roughened crest which causes the disintegration of overflow was found to increase the reaeration efficiency significantly. On the basis of the results of the experiments, the pilot construction of the labyrinth welt with included angle of 30 degree was made. The labyrinth weir was made up by assembling the frame and then filling the ripraps into the frame. The ripraps were exposed at the crest to split the overflow. The average value of oxygen transfer efficiency observed at the pilot weir was 0.18. It is expected that the results from the experimental study and the field data of the pilot weir would serve for the improvement of water quality by the weirs with high reaeration efficiency.

• Economic and Environmental Geology
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• v.53 no.3
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• pp.235-244
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• 2020

Copper (Cu), one of the main contaminants in the mine drainage from the closed mine area, needs to be removed before exposed to environment because of its toxicity even in the low concentration. In this study, passive treatment based field pilot experiments using limestone and compost media were conducted during 9 months for enhancing Cu removal efficiency of the mine water treatment facility of S mine located in Goseong, Gyeongsangnam-do in South Korea. The pH increase and Cu removal efficiency showed high value at Successive Alkalinity Producing System ( SAPS) > Reducing and Alkalinity Producing System (RAPS) > limestone reactor in a sequence. The compost media using in SAPS and RAPS contributed to raise pH by organic material decomposition with generating alkalinity, thus, Cu removal efficiency increased. Also, experimental results showed that Cu removal efficiency was proportional to pH increase, meaning that pH increase is the main mechanism for Cu removal. Moreover, Sulfate Reduction Bacteria (SRB) was identified to be most activated in SAPS. It is inferred that the sulfate reduction reaction also contributed to Cu removal. This study has the site significance in that the experiments were conducted at the place where the mine water generates. In the future, the results will be useful to select the more effective reactive media used in the treatment facility, which is most appropriate to remediate mine water from the S mine.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.53-56
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• 1991

산업구조의 급속한 발전과 공업화는 사회구조의 변화 및 대도시로의 인구집 중, 고밀도화, 교통량의 증가를 초래하여 이로부터 기인한 도시지역의 환경 오염 문제는 쾌적한 인간생활을 위협하는 단계에까지 이르렀다. 그중에서 소 음에 관한 문제도 대기 및 수질의 오염과 동시에 도시생활 환경에 많은 영 향을 미치게 되었다. 도시 소음의 주 원인은 주로 도로교통소음이며 이는 기 하급수적으로 늘어가는 자동차의 양에 의해 더욱 심해지고 있다. 따라서 현 재 우리나라에서도 주거지역 및 준주거지역 등의 지역별 소음도 규제 및 신 설되는 공동주택 단지에서의 소음레벨규제등이 있긴 하나 이들은 상당히 소 극적이며 미온적일 뿐 아니라 실제 거주하는 주민들의 반응과는 상당한 차 이를 보이고 있으며 더욱이 주민의 소음에 대한 주관적 반응을 적절히 표현 할 수 있는 지표마저 명확하지 않은 실정이다. 이러한 관점에서 본 고찰에서 는 피험자들의 주관적 반응을 실험할 때 발생하는 변수요인들을 통제 할 수 있는 실험 실시행 청감실험을 실시하기에 앞서 대상지역의 도로교통소음을 여러가지 평가척도에 의해 평가한 후 그 현장에서 이 소음에 노출된 피험자 들의 반응을 파악하여 청취자들이 인지하는 소음레벨을 적절히 평가하는 지 표를 찾고자 한다.