• Journal of Environmental Impact Assessment
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• v.16 no.6
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• pp.381-391
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• 2007

The air quality modeling was carried out to assess the impact of air quality for large scale urban development. The site for the assessment is Multi-fuctional Administrative City which locates in Yeongi-gun, Chungcheongnam-do and estimated population in 2030 is 500,000. Two automatic weather monitoring stations were installed to monitor the meteorological variables for a year and upper air meteorological parameters were measured using radiosonde for 5 days with 4 hours interval in every season. The air quality of standard air pollutants were also measured for 5 days continuously in every season. The results of wind field analysis based on the site measurements and CALMET modeling showed that the valley and mountain winds were prevailed when the sypnotic wind was weak. It also showed that wind speed and directions were highly space-variable within the site basin. The variable wind characteristics implies that the Gaussian dispersion model such ISC3 and AERMOD are not appropriate and the unsteady-sate Lagrangian model such as CALPUFF is preferable. CALPUFF model was applied to assess air quality impact of new sources. The new sources were those for individual and group heating facilities as well as the traffic increases. The results showed that the estimated concentrations of CO and $SO_2$ pollutants by summing the impact concentration of new sources by the dispersion model and the ambient air concentrations by the site measurements were acceptable but those of PM-10 and $NO_2$ would violate ambient air quality standards at several locations due to high ambient air concentrations. It is recommended that the emission reductions near the site should be enforced to improve the ambient air quality.

• Journal of the Korean Society of Safety
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• v.35 no.2
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• pp.67-75
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• 2020

Due to various industrial accident that occur to the staff in the broadcasting production sites, the issue of safety at the broadcast production site is becoming a social issue. Nevertheless, not many researches have been carried out on the actual conditions of the staff's production environment and its safety issues. Therefore, the purpose of this study was to prepare a countermeasure based on engineering knowledge by analyzing working environment to improve the poor working environment of staff. First, this study analyzed statistical data of industrial accidents over the past five years to find out the current status of disasters at broadcasting production sites. As a result, the intensity of the accident was not weak in that the loss days was more than one month in 85% of accident. In addition, the type of accident was high in the fall/trip accidents. Second, this study visited 10 broadcasting production sites for risk assessment. By analyzing the characteristics of the working environment and 104 questionnaires, we predicted the types of accidents that can occur in the broadcasting production site. As a result, accident types such as fall, collision, and trip were relatively high, similar to the characteristics of construction site. Third, it was possible to quantify the scale of the risk in the broadcasting production, and as a result, the quantity of temporary structure and accident risk were proportional. In other words, this study analyzes broadcasting work environment and defines risk factors based on safety engineering knowledge. Finally, this study suggested a guideline to improve the safety of the broadcasting production site.

• Environmental Engineering Research
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• v.21 no.2
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• pp.152-163
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• 2016

Present study investigates the potential of cassava peel and rubber tree bark for the removal of Cr (VI) from aqueous solution. Removal efficiency of more than 99% was obtained during the kinetic adsorption experiments with dosage of 3.5 g/L for cassava peel and 8 g/L for rubber tree bark. By comparing popular isotherm models and kinetic models for evaluating the kinetics of mass transfer, it was observed that Redlich-Peterson model and Langmuir model fitted well ($R^2$ > 0.99) resulting in maximum adsorption capacity as 79.37 mg/g and 43.86 mg/g for cassava peel and rubber tree bark respectively. Validation of pseudo-second order model and Elovich model indicated the possibility of chemisorption being the rate limiting step. The multi-linearity in the diffusion model was further addressed using multi-sites models (two-site series interface (TSSI) and two-site parallel interface (TSPI) models). Considering the influence of interface properties on the kinetic nature of sorption, TSSI model resulted in low mass transfer rate (5% for cassava peel and 10% for rubber tree bark) compared to TSPI model. The study highlights the employability of two-site sorption model for simultaneous representation of different stages of kinetic sorption for finding the rate-limiting process, compared to the separate equilibrium and kinetic modeling attempts.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.109-110
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• 2008

We have performed a density functional theory study to investigate the reaction of the $HfCl_4$ molecule on $H_2O$ terminated Si (001)-$(2\times1)$ surface. The reaction of the $HfCl_4$ molecule is more favorable on OH-terminated site than H-terminated site. The first $HfCl_4$ molecule is adsorbed on a OH-terminated site with 0.21 eV energy benefit. The second $HfCl_4$ molecule is adsorbed on the most adjacent OH-terminated site of the first molecule and the energy benefit is 0.28 eV. The third and forth molecules have same tendency with the first and second ones. The adsorption energies of the fifth and sixth $HfCl_4$ molecules are 0.01 eV, -0.06 eV respectively. Therefore, we find that the saturation Hf coverage is approximately 5/8 of the available hydroxyl site, which is $2.08\times10^{14}/cm^2$. Our model is well matched with an experimental study by reference.

• Environmental Engineering Research
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• v.24 no.2
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• pp.331-338
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• 2019

Particulate matter (PM) was collected using micro-orifice uniform deposit impactors from a residential (RES) site and an industrial (IND) site in Ulsan, South Korea, in September-October 2014. The PM samples were measured based on their size distributions (11 stages), ranging from $0.06{\mu}m$ to over $18.0{\mu}m$. Nine trace metals (As, Se, Cr, V, Cd, Pb, Ba, Sb, and Zn) associated with PM were analyzed. The PM samples exhibited weak bimodal distributions irrespective of sampling sites and events, and the mean concentrations of total PM (TPM) measured at the IND site ($56.7{\mu}g/m^3$) was higher than that measured at the RES site ($38.2{\mu}g/m^3$). The IND site also showed higher levels of nine trace metals, reflecting the influence of industrial activities and traffic emissions. At both sites, four trace metals (Ba, Zn, V, and Cr) contributed to over 80% of the total concentrations in TPM. The modality of individual trace metals was not strong except for Zn; however, the nine trace metals in $PM_{2.5}$ and $PM_{10}$ accounted for approximately 50% and 90% of the total concentrations in TPM, respectively. This result indicates that the size distributions of PM and trace metals are important to understand how respirable PM affects public health.

• Korean Journal of Construction Engineering and Management
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• v.22 no.1
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• pp.13-26
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• 2021

To promote the off-site construction (OSC) in Korea, technical innovation applied to each phase, such as design, engineering, factory production, and site assembly, is important and equally necessary is the development of management and operation methods that are different from existing construction production methods. However, the current OSC-related studies in Korea are conducted from the technical development viewpoints, such as construction methods. Additionally, few studies have been conducted to derive a management measure for successful OSC projects. Therefore, studies to derive a management measure based on a clear understanding of the core success factors of OSC projects are required. This study aims to analyze several studies related to the success factors of OSC projects conducted overseas and to show its core implications for the successful management of OSC projects in Korea. We expect this study to improve the viability of OSC projects, which will be expanded in Korea in the future.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.5
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• pp.233-247
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• 2024

The damage to structures during an earthquake can be varied depending on the frequency characteristics of seismic waves and the geological properties of the ground. Therefore, considering such attributes in the design ground motions is crucial. The Korean seismic design standard (KDS 17 10 00) provides design response spectra for various ground classifications. If required for time-domain analysis, ground motion time series can be either selected and adjusted from motions recorded at rock sites in intraplate regions or artificially synthesized. Ground motion time series at soil sites should be obtained from site response analysis. However, in practice, selecting suitable ground motion records is challenging due to the overall lack of large earthquakes in intraplate regions, and artificially synthesized time series often leads to unrealistic responses of structures. As an alternative approach, this study provides a case study of generating ground motion time series based on the hybrid broadband ground motion simulation of selected scenario earthquakes at sites in the Nakdonggang delta region. This research is significant as it provides a novel method for generating ground motion time series that can be used in seismic design and response analysis. For large-magnitude earthquake scenarios close to the epicenter, the simulated response spectra surpassed the 1000-year design response spectra in some specific frequency ranges. Subsequently, the acceleration time series at each location were used as input motions to perform nonlinear 1D site response analysis through the PySeismoSoil Package to account for the site response characteristics at each location. The results of the study revealed a tendency to amplify ground motion in the mid to long-period range in most places within the study area. Additionally, significant amplification in the short-period range was observed in some locations characterized by a thin soil layer and relatively high shear wave velocity soil near the upper bedrock.

• Journal of Environmental Impact Assessment
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• v.15 no.4
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• pp.271-277
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• 2006

In this study, we investigated the applicable plan of GIS on the environmental impact assessment of 60 Hz Powerline. So we assessed distance data based on calculations by use of 2D and 3D Geographical information systems(GIS) and distance data based on measurements on 1: 5000 maps accord with on site distance measurements to use input data for calculating magnetic field. One hundred eight of the on site measured addresses were selected from residences. The data were achieved by measuring the distance between residence and power line on maps with scales of 1: 5000. The digital map was obtained from National Geographic Information Institute with scales of 1: 5000, and we made 2D and 3D map. Correlation analyses were performed for statistical analyses. For the 3D GIS versus on site comparison of different exposure categories, 70 of 108 measurements were assigned to the correct category. Similarly for 2D GIS versus on site comparison, 71 of 108 were correctly categorized. When comparing map measurement with on site measurement, 62 of 108 were correctly categorized. When the correlation analysis was performed, best correlation was found between 3D GIS and on site measurements with r = 0.84947 (p<0.0001). The correlation between map and on site measurement yielded an r of 0.76517 (p<0.0001). Since the GIS measurements and map measurement were made from the center point in the building and the on site measurements had to be made from the closest wall on the building, this might introduce and additional error in urban areas. The difference between 2D and 3D calculations were resulted from the height of buildings.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.459-462
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• 2007

Recently, it has been important issue to recycle the rapid increase of construction waste. The site-recycling of construction waste has been one of alternatives to recycle construction waste. The economic superiority of site-recycling was shown in previous studies, but it is hardly studied in the Quantification of social costs from site-recycling. This study identified the generation of the carbon dioxide from the site-recycling and Quantified the social costs of it. Also, this study performed the comparison and analysis of the social costs of the carbon dioxide in accordance with the aggregate production from the site-recycling, processing on commission, and a stony mountain. The results of this study indicated that the site-recycling was the most effective in the social costs.

• Korean Journal of Materials Research
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• v.17 no.7
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• pp.358-360
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• 2007

Cobalt subtitution on NiSi is investigated by using an ab-initio calculation. Firstly, a relaxed NiSi structure is calculated and the calculated lattice parameters are compared with experimentally determined lattice parameters. The calculated values are smaller than the experimental values by about 2%. As the calculation is based on 0 K, and the experimental measurement is performed at room temperature, those values are in good agreement. Next, a Co atom substitutes a Ni and Si site, respectively, to evaluate the preferable site between them. Co prefers Ni site to Si site. The calculated total energy also indicates that the Co substitution to Ni site stabilizes the NiSi structure. Therefore, the thermal stability of NiSi with Co addition can be achieved by the structure stabilization of NiSi by Co substitution into Ni site of NiSi.