• International conference on construction engineering and project management
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• 2013.01a
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• pp.213-218
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• 2013

To respond to global warming and climate change, Korean Government has implemented the GHG Target Management, which leads to a voluntary reduction in greenhouse gases from large businesses. Korean universities have put efforts on reducing GHG emissions and energy consumptions in the campuses, however, because of various activities and its characteristic of non-profit organization, establishing a long-term plan for reducing greenhouse gases is necessary. In this research, the Seoul National University's energy usage is analyzed and applicable technologies for reducing GHG emissions are extracted. Hence, three scenarios for performing the GHG Target Management are established. Proposed scenario is available for GHG Target Management and it would be expected to support decision- makings for reducing GHG emissions.

• Journal of the Korea Institute of Building Construction
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• v.8 no.1
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• pp.91-96
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• 2008

This study is to investigate the influence of the over-added chemical agents, such as water reducing agent(WRA) and AE water reducing agent(AEWRA), on the physical properties of concrete to estimate the degree of damage due to over-added chemical agents. For the fresh concrete, slump and slump flow increased with the increase of WRA and AEWRA as expected. Material segregation phenomenon was observed with the over dosage of lignin based AEWRA about 4 times larger than recommended dosage. The over dosage of AE water reducing agent about 4 times larger than recommended dosage resulted in an increase of air contents remarkably. The set retardation occurred greatly with the increase of AEWRA and WRA. For the properties of the hardened concrete corresponding to the over dosage of AEWRA, it is found that compressive strength of over added AEWRA and WRA concrete are much smaller than those of base and recommended dosage concrete proportionally due to associated increasing air content.

• Fire Science and Engineering
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• v.27 no.1
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• pp.26-30
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• 2013

It is necessary to use pressure reducing valves to provide required water pressure in water-based fire suppression systems of the tall buildings. In many cases, however, pressure reducing valves lose their function due to the phenomenon of pressure equalization caused by valve leak. This study carried out performance evaluation of the recently developed pressure reducing valve to prevent pressure equalization and found it can maintain designed pressure reducing ratio within 11% variation and prevent pressure equalization by automatic self-lock function of the piston.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1125-1128
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• 2007

In order to improve the acoustic performance of a noise barrier without increasing its height, various type of acoustic devices are suggested but, there is no proper method to estimate the performance in Korea. For this, an outdoor test facility was established in Expressway and Transportation Technology Institute(ETTI) of Korea Expressway Corporation for testing the acoustical performance of noise reducing devices installed on the top of a noise barrier. Noise measurements before and after installation of the noise reducing devices were carried out by using sound pressure level for long distance range from the barrier, from 10m to 40m. For considering the directivity effects of noise reducing devices, multivariate regression analysis was attempted.

• Journal of Environmental Impact Assessment
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• v.16 no.1
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• pp.27-33
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• 2007

Hexavalent chromium-contaminated soils are encounted at many unregulated discharge and improper handling of wastes from electroplating, leather tanning, steelmaking, corrosion control, and wood preservation industries. Contamination of hexavalent chromium in the soil is a major concern because of its toxicity and threat to human life and environment. Current technologies for hexavalent chromium-contaminated soil remediation are usually costly and/or cannot permanently prohibit the toxic element from entering into the biosphere. Thus, as an alternative technique, immobilization is seen as a cost-effective and promising remediation technology that may reduce the leachable potential of hexavalent chromium. The purpose of this paper is to develope an immobilization technique for the formation of the geochemically stabilized hexavalent chromium-contaminated soil from the reactions of labile soil hexavalent chromium forms with the added soluble phosphate and chromium reducing agent. From the liquid phase experiment, reaction order of chromium reducing agent, soluble phosphate, alkali solution shows the best removal efficiency of 95%. In addition, actual soil phase experiment demonstrates up to 97.9% removal efficiency with 1:1 molar ratio of chromium reducing agent and soluble phosphate. These results provide evidence for the potential use of soluble phosphate and chromium reducing agent for the hexavalent chromium-contaminated soil remediation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.155-161
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• 2008

The grounding systems provide a low resistance path for fault or normal currents into the earth. The material for reducing ground resistance is buried around the grounding electrode to increase its effective size of the electrode and thus to obtain low ground resistance. Increasing the contacting area with the grounding electrode is effective for lowering the ground resistance in soils. Using this idea the conductive expansion ground resistance reducing material was developed. In this paper experimental data has shown that the ground resistance reduction method using proposed material is superior to using a typically available commercial ground resistance reducing material.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.63-68
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• 1998

The fluidity of high flowing concrete can be affected by numerous parameters which characterize either the cement of the admixture. The reactivity of a cement as determined by its chemical composition(especially its $C_3$A content), its fineness and its content in sulfates and alkalies obviously plays a key role in rheology of high flowing concrete in fresh state. Specific properties of high range water reducing AE agent used to enhance the workability of high flowing concrete also exert important influence. The purpose of this experimental study is to investigate and analyze the effect of cement and high range water reducing AE agent in fluidity, setting, compressive strength of high flowing concrete. As a result, we found that fluidity of high flowing concrete is affected greatly by kind of cement and high range water reducing AE agent, also, there is harmonic character between high belite cement and polycarbonic acid high range water reducing AE agent.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.496-499
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• 2008

The noise reducing devices installed on the noise barrier have been developed in many shapes and ways to reduce noise around road traffic areas. In this study, test and estimation method for the noise reducing device witch installed on the top of a noise barrier was suggested. For this, the authors have considered sound power flow around the device and sound pressure levels for the far field area. To estimate the area effect behind the barrier, area average of noise pressure level difference divided by two area, upper and bellow the sight-line. Comparing the attenuation difference of these areas, the tendency of noise reduction effect was studied according to type of noise reducing devices. Compared with noise shielding efficiency of the devices that using equivalent height of a simple barrier calculated by the SoundPlan, the commercial environment noise simulation software.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.207-210
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• 2004

Effect of electron accepters on anaerobic degradation of petroleum hydrocarbons by an anaerobic sludge taken from a sludge digestion tank in a soil artificially contaminated with 10,000 mg/kg soil of diesel fuel was tested. Treatments of soil with 30 mL of the digestion sludge (2,000 mg/L of vss (volatile suspended solids)) were incubated under several anaerobic conditions including nitrate reducing, sulfate reducing, methanogenic, and mixed electron accepters conditions for 120 days. Treatments with the digested sludge showed significant degradation of diesel fuel under all anaerobic conditions compare to control treatments with an autoclaved sludge and without the sludge. The amount of TPH degradation after 120days incubation was the largest in the treatment with the sludge and mixed electron accepters (75% removal of TPH) followed in order by sulfate reducing, nitrate reducing, methanegenic condition as 67%, 53％, 43%, respectively. However, the rate of TPH degradation in the nitrate- and sulfate reducing condition within 105 days were comparable with that of the mixed electron accepters condition. Microorganisms in each electron acceptor condition were plated on solid mediums containing nitrate or sulfate as sole electron acceptor and several nitrate- and sulfate reducing bacteria showed effective degradation of diesel fuel within 30 days incubations. These results suggest that anaerobic degradation of diesel fuel in soil with digested sludge is effective for practical remediation of soil contaminated with petroleum hydrocarbons.

• Journal of Environmental Health Sciences
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• v.40 no.6
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• pp.484-491
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• 2014

Objectives: A radon emission reducing agent was prepared using charcoal and zeolite, and the amount was measured after coating construction materials with the agent. The availability of the radon emission reducing agent was evaluated. Methods: Construction materials (red brick, cement brick, and gypsum board) coated with reducing agent were placed in a chamber to measure radon emissions. The construction materials were coated one through three times. The spread volume for brick and gypsum board was 50 mL and 75 mL per application, respectively. The amount of radon emitted was measured by RAD-7 after 48 hours. Results: The reduction ratio increased with the number of coatings, and the reduction ratios for red brick, cement brick, and gypsum board were 63.3, 73.6, and 58%, respectively, in the case of three coatings of RA-1. The reduction ratios for red brick, cement brick, and gypsum board were 42.8, 58.1, and 26.2%, respectively in the case of three coatings with RA-2. RA-1 was slightly better than RA-2 in radon emission reduction. Conclusions: Radon emissions from construction materials decreased according to the concentration of reducing agent coating, and it was more effective than existing methods.