• 한국물환경학회지
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• 제26권5호
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• pp.747-753
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• 2010

A series of experiments with a laboratory scale ultrasound treatment system for MTBE polluted groundwater was performed to increase the efficiency of MTBE degradation in groundwater. This study evaluated several factors to increase the efficiency of MTBE treatment for artificial and natural groundwater. The treated volume of groundwater, ultrasound frequency and power, and pollutant concentrations have been changed to evaluate its effects on the degradation efficiency of MTBE in batch and continuous flow reactor. For the specific experimental conditions on this paper, MTBE degradations are more efficient at 580 kHz than those at 1 MHz. The efficiency of MTBE degradation is proportional to the intensity of ultrasound power per unit volume of MTBE polluted groundwater. The concentration of ions in groundwater does not much affect the efficiency of MTBE degradation. The $1^{st}$ order degradation constant of MTBE for different power per unit volume at 580 kHz shows linear relationship at same concentration. The $1^{st}$ order degradation constant for 0.1 mM MTBE solution is higher than that for 1 mM MTBE solution. These experimental results could be helpful to seek optimal conditions for relatively large volume of polluted groundwater treatment.

• 대한환경공학회지
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• 제33권11호
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• pp.797-803
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• 2011

본 연구에서는 물 사용관련 주요 지표인 1인1일 급수량을 이용하여 수요관리 추진 결과 분석 및 절감량을 산정하고, 수요관리를 통하여 발생하는 절감량을 물 수급전망에 연계할 수 있는 시스템을 개발하였다. 1인1일 급수량 분석결과 상수도 여건이 열악한 지자체는 상수도 보급 개선이 선행되어야 하며, 장래용수수요량 추정시에도 이를 고려하여야 할 것으로 판단된다. 금강권역을 대상으로 수요관리 절감량을 산정하고 K-WEAP (Korea-Water Evaluation And Planning System)을 이용하여 물수지분석을 수행한 결과 하천유량 변화 및 지하수와 저수지저수량 증가를 확인하였으며, 이는 다른 용도로 활용 가능하다고 판단된다.

• 화약ㆍ발파
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• 제21권1호
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• pp.41-47
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• 2003

도로, 항만, 터파기 등의 공사에서 대량의 발파 작업이 선행되는 경우가 빈번하다. 발파작업은 시공을 맡은 원청 회사측에서 직접 행하는 수도 있지만 대개는 전문적으로 발파를 시행하는 업체에게 하청을 주게 마련이다. 이럴 경우 종종 발파작업이 완료된 이후 원청회사와 하청회사 사이에 발파작업 수량에 대한 원만한 합의를 보지 못할 경우가 있는 이럴 경우 쌍방 혹은 쌍방이 위임한 제3자가 발파작업 수량을 추정하게 된다. 사후에 발파작업수량을 추정하는 방법으로는 일위대가표를 적용한 추정, 시행된 발파의 비장약량을 적용한 추정, 발파작업일보를 비교하여 뇌관당 발파암량을 적용하는 방법들이 있다. 본 연구에서는 특정한 사례를 통하여 뇌관당 발파암량을 적용하여 발파작업수량을 추정하는 방법을 소개하고 이 방법이 다른 여타의 추정 방법에 비하여 가장 신회성이 높음을 입증하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.134-135
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• 2015

This study analysed compressive strength and the expansion characteristic to utilize a high volume mineral admixture mortar for a aerated mortar and a plastering mortar. In this experiment, the result shows that the compressive strength gain was satisfactory in case that WR was replaced within 5%. Also, the difference between WR1 and WR was insignificant. It shows that the drying shringkage properties at large was showed being satisfactory generally compared with Plain when WR was replaced, but the effect was not significant.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.57-60
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• 2003

Generally, normal concrete has the disadvantages of low tensile strength, low ductility and volume instability. To improve its performance, fiber reinforced cimentitious composite(FRCC) have been development. These composites are composed of cement, sand, water, a small amount of admixtures, and an optimal amount of fiber like synthetic fiber and steel fiber. This research investigates influence of sand, hybrid fiber and fiber volume fraction, and reports the test results of mechanical properties, fracture behavior and failure pattern of the FRCC. Our experiment was observed that sand mixed FRCC has lower compressive strength and higher bending strength than no sand mixed FRCC, and more steel fiber mixed FRCC has higher compressive strength and bending strength. Hybrid FRCC of steel and polypropylene had superior properties than FRCC of polypropylene only in same fiber volume fraction.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.103-104
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• 2019

The aim of the research is assessing the possibility of recovering the compressive strength of the mortar mixture replaced excessively high volume of blast furnace slag accidently. As a result of the experiment, in the case of compressive strength, painting sodium oxide showed higher compressive strength recovery effect than painting calcium oxide. As a curing temperature, 20℃ showed advanced result rather than 65℃. From the wet curing, the reaction was confirmed, deeper penetration depth was checked at 20℃ than 60℃ temperature. Therefore for the concrete mixture with excessively high volume of blast furnace slag, it is considered that painting sodium hydroxide and curing 20℃ can recover the compressive strength effectively.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.32-33
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• 2019

This study evaluated the effect of amorphous steel fibers on the spalling characteristics of high-strength concrete. with mix proportions of polypropylene (PP) fibers of 0.15% by concrete volume, and proportions of amorphous steel fibers of 0.3% and 0.5% by concrete volume. In the range of 0.3 vol% of amorphous steel fiber, the effect of suppression of the spalling and the prevention of degradation of strength was shown, but it was evaluated to be ineffective in the suppression of the spalling due to interferences in formation of pore network in the range of 0.5 vol.%.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.35-36
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• 2013

Electric arc furnace oxidizing slag from massively produced steel slag has been used in road bases and subbases, hot mix asphalt, and landfill. Electric arc furnace oxidizing slag contains iron (15%~30%) and has a high density of 3.0~3.7 ton/m3. Depending on the type and amount of concrete aggregates, the radiation-shielding characteristics can vary. Therefore, aggregates of electric arc furnace oxidizing slag can be considered for the production of radiation-shielding concrete. The experimental design of this study is experiments on Compressive strength experiments, X-ray irradiation experiments, and experiments related to the unit volume weight were carried out on hardened concrete. This experiment compared the performance evaluation of radiation shielding of concrete using electric arc furnace oxidizing slag.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.213-214
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• 2022

The purpose of this study is to compare and analyze the effect of the length and volume fraction of smooth steel fiber on the electrical conductivity and shielding effectiveness of cementitious composites. As the length and volume fraction of the fiber increase, the movement of electrons becomes active and the formation of a conductive path becomes advantageous, thereby increasing electrical conductivity. Accordingly, the electrical conductivity and the shielding effectiveness showed a very close relationship. Thereafter, it is judged that research is needed to increase the shielding effect.

• Computers and Concrete
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• 제7권5호
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• pp.421-435
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• 2010

This paper utilizes the modified Davis model and the mode coupling theory, as parts of the electrolyte solution theory, to investigate the diffusivity of the ion in concrete. Firstly, a computational model of the ion diffusion coefficient, which is associated with ion species, pore solution concentration, concrete mix parameters including water-cement ratio and cement volume fraction, and microstructure parameters such as the porosity and tortuosity, is proposed in the saturated concrete. Secondly, the experiments, on which the chloride diffusion coefficient is measured by the rapid chloride penetration test, have been carried out to investigate the validity of the proposed model. The results indicate that the chloride diffusion coefficient obtained by the proposed model is in agreement with the experimental result. Finally, numerical simulation has been completed to investigate the effects of the porosity, tortuosity, water-cement ratio, cement volume fraction and ion concentration in the pore solution on the ion diffusion coefficients. The results show that the ion diffusion coefficient in concrete increases with the porosity, water-cement ratio and cement volume fraction, while we see a decrease with the increasing of tortuosity. Meanwhile, the ion concentration produces more obvious effects on the diffusivity itself, but has almost no effects on the other ions.