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Lee J.,Environmental and Plant Engineering Institute | Kim I.,Environmental and Plant Engineering Institute | Kim I.,Korean University of Science and Technology | Chang S.,University of Seoul
Environmental Engineering Research | Year: 2015

Transparent type noise barrier is a desirable facility since it provides a secure view to drivers and passengers. However, reflection from this type of barrier could annoy dwellers on the sides of the road. To reduce reflection noise by transparent type barrier, modification can be made to the shapes on the front side and hence get effects by distortion of sound transmission. To achieve this, we have conducted simulation by which the effects of patterned screens of noise barrier on high-ways were investigated. The reduction effects of reflected sounds were evaluated for swelling, swelling with curved, rectangular and V-shaped screen type barriers, compared to the planar panel. The emitting noise was generated by 6-lane road and the patterned noise barriers had shown the reduction effects, especially in swelling and swelling with curved type for middle height dwellers, and the V-shaped screen type for higher elevation dweller. The swelling-type showed a decrease of 0.7~1.2 dB, performing the best diminution effect among the tested noise barriers. © 2015 Korean Society of Environmental Engineers. Source


Han S.,Yonsei University | Han S.,Environmental and Plant Engineering Institute | Hwang H.,Environmental and Plant Engineering Institute | Kim S.,Yonsei University | And 2 more authors.
Sustainability (Switzerland) | Year: 2015

The ultimate goal of urban water infrastructure asset management may be sustainable water supply with satisfaction for customers. In this work, we attempted to evaluate the gaps between the perspectives of customers and service providers in Korea's water infrastructure asset management. To evaluate the customers' perspective, a hierarchical questionnaire survey was conducted to estimate the weights of influence for six customer values and their attributes on Korean water utility management. To evaluate the service providers' perspective, an AHP (Analytic Hierarchy Process) analysis was performed to estimate the weights of influence for the customer values and their PIs (performance indicators). The gap analysis results show that customers place higher value on customer service satisfaction (emotion and information) than do the service providers (managers), whereas the managers place more value on affordability than do the customers. The findings from this work imply that improving customer service is effective in satisfying the desirable water LOS (level of service) for customers. Recommendations have also been provided for administrators and engineers to develop integrated decision-making systems that can reflect customer needs regarding the improvement of their water infrastructure asset management. The findings from this work may be helpful for the Korean government and water supply utilities in improving the sustainability of their water infrastructure asset management. © 2015 by the authors. Source


Lee J.-Y.,Environmental and Plant Engineering Institute | Lee H.-D.,Environmental and Plant Engineering Institute | Lee H.-D.,Korean University of Science and Technology | Lee I.K.,Environmental and Plant Engineering Institute | Lee I.K.,Korean University of Science and Technology
International Journal of Multimedia and Ubiquitous Engineering | Year: 2015

Bio-toxicity using luminescence of PFOA and PFOS was assessed by photomultiplier tube. The assessment was evaluated based on EC50 and transient profile in time with varying concentration of 0.0~250 mg/L in 6 steps. As a result, the toxicity was found out to be 150.3 and 237.7 in EC50 for PFOA and PFOS, respectively. Besides, the profiles depicted that PFOA is more toxic than PFOS. As a result of applying 1CFOK model where actual toxic kinetics were applied, high kinetics parameters showing biological concentration or damage were drawn in case of PFOA. Also, it is determined that PFOA has a significant effect of chronic toxicity on the residual concentration. PFOS does not show a higher toxicity than PFOA, but it shows a fatal toxicity at near 250 mg/L and it can be concentrated, so measures for this substance are necessary. © 2015 SERSC. Source

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