• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1346-1353
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• 2007

The simulation analysis of fire-driven flow and passenger evacuation in Daegu subway station, Chung-Ang, have been performed. The first location of outbreak of fire is inside passenger car in the third basement in Chung-Ang station. The smoke flow in the second and third basement has been analyzed using FLUENT 6.2. The CO(carbon monoxide) and temperature distribution in the train units and station platform have been obtained and transferred to input data for evacuation simulation. The highest temperature in the train units was 1500K. For the simulation of passenger evacuation, EXODUS has been used for whole basements (level 1${\sim}$ level 3) in the station. Total number of people was assumed to be one thousand and 640 were placed inside train and 360 were placed outside train. In evacuation simulation, an average of 135 passengers were killed and an average time to evacuate takes 10min 19sec. The main evacuation routes used by passengers were investigated and the cause of death was identified by evacuation simulation.

• Composites Research
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• v.26 no.6
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• pp.355-362
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• 2013

Carbon particle based nanocomposites have been studied. Nanocomposites containing CNT and graphite particles were manipulated by aligning the micro/nano-size particles with electric field. Electric field is applied to the suspension of epoxy matrix and particulate inclusions in order to align them along the direction of the electric field. Particles aligned in a uniform direction act as a fiber in a CFRP composite. The mechanical strength and physical characteristics highly depend on particles' distribution pattern and amount. In this study, the characteristics of radioactive barrier are emphasized, which has been rarely discussed in the literature. A number of sample coupons were tested to verify their performance. The procedure of manufacturing nanocomposites by means of extremely small size particle alignment is presented in sequence. Several physical and structural performances of composites containing aligned and randomly distributed particles were compared. The results show particle alignment is very effective to enhance directional strength and radioactive barrier performance.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.3
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• pp.1-15
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• 2012

The objective of this study is to analyze the distribution of urban parks and its problems in a city in Gyeonggi-do where new towns and old towns are mixed. The study will also analyze and understand the unbalanced deployment of urban parks - rest areas and carbon absorbers of an entire city - between old towns and new towns, suggest improvement opportunities and examine and suggest plans to create and expand urban parks in old cities that lack urban parks. Findings showed that first, new towns were 1.2~1.6 higher than old towns in the number of parks, park area, and per capita park area, indicating that parks were unbalanced across towns. Second, as for a plan for improving the unbalanced deployment of urban parks, when the use area needs to be changed in an urban development project, it was suggested to donate 10% of the project site to the city to create it into a park and it was suggested to identify and proactively improve alternative park resources that can replace parks such as rivers and recreational sites. Third, regarding a plan for improving urban parks in old towns, it was suggested to secure urban parks by attracting various urban development projects to old town areas. The amendment of related laws was proposed to double required park area to $6m^2$ per household. Amendments were also suggested for one law and four guidelines to specifically define the location of urban parks as well.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.700-707
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• 2003

Surface sediments in the mouth area of Jinhae Bay were investigated to evaluate the benthic environment in terms of geochemical criteria and macrobenthos abundance. Characteristics of the surface sediment distribution exhibited muddy sediments in the most part of study area. Some mixed sediments of coarse sand and mud were distributed along the coastal area of Geoje Island and around the Jeo Islands. Organic matter from ignition loss and total organic carbon from CHNS varied between $8.8-1.7\%,\;and\;4.62-0.77\%,$ respectively. The source of organic matter based on the C/S ratio was mixed with in situ biogenic and terrigenous organic matter. The C/S ratio of organic matter also suggested both an anoxic bottom condition in several parts of the study area. The content of hydrogen sulfide in surface sediment was extremely variable and showed spatio-temporal variation from site to site. In several locations, the content of hydrogen sulfide as an index of eutrophication was over the critical value (0.2 mg/g), suggesting that several parts of the study area were not favorable for the habitat of macrobenthos. The relationship among the number of individuals of marcrobenthos, hydrogen sulfide, and organic matter was not clear, but a potential negative relationship between individuals of marcrobenthos and hydrogen sulfide was indicated.

• Journal of Hydrogen and New Energy
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• v.25 no.4
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• pp.378-385
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• 2014

In this research, we investigate electrical performance and electrochemical properties of graphene supported Pt (Pt/G) and PtM (M = Ni and Y) alloy catalysts (PtM/Gs) that are synthesized by modified polyol method. With the PtM/Gs that are adopted for oxygen reduction reaction (ORR) as cathode of proton exchange membrane fuel cells (PEMFCs), their catalytic activity and ORR performance and electrical performance are estimated and compared with one another. Their particle size, particle distribution and electrochemically active surface (EAS) area are measured by TEM and cyclic voltammetry (CV), respectively. On the other hand, regarding ORR activity and electrical performance of the catalysts, (i) linear sweeping voltammetry by rotating disk electrode and rotating ring-disk electrode and (ii) PEMFC single cell tests are used. The TEM and CV measurements demonstrate particle size and EAS of PtM/Gs are compatible with those of Pt/G. In case of PtNi/G, its half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production % are excellent. Based on data obtained by half-cell test, when PEMFC singlecell tests are carried out, current density measured at 0.6V and maximum power density of the PEMFC single cell employing PtNi/G are better than those employing Pt/G. Conclusively, PtNi/Gs synthesized by modified polyol shows better ORR catalytic activity and PEMFC performance than other catalysts.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1063-1072
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• 2000

Kinetic tests on pyrolysis of the mixture of waste automobile lubricating oil and polystyrene were carried out with thermogravimetric technique at the heating rates of 0.5, 1.0, $2.0^{\circ}C/min$ in a stirred batch reactor. The activation energy and the reaction order were determined at conversions of 1 to 100% using differential method. The mixture of waste automobile lubricating oil and polystyrene was pyrolyzed at lower temperature rather than waste automobile lubricating oil and polystyrene. respectively. Also, the thermal decomposition took place in two broad reaction steps. The pyrolyzed oil of mixture represented high selectivity of styrene monomer and dimer like that of polystyrene pyrolyzed products.

• Ocean and Polar Research
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• v.41 no.2
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• pp.47-61
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• 2019

The Dokdo coast is known for its high biodiversity. However, few studies have examined the biodiversity and macrobenthic community on the subtidal soft-bottom. Therefore, we collected macrobenthos (> 1 mm) using a Smith-McIntyre grab ($0.1m^2$) at 15 stations along the Dokdo coast in September 2016. The sediments consisted of badly sorted (1.7) coarse sand with gravel and the mean sediment grain size was $-0.4{\phi}$. In total, 177 macrobenthic species were collected; their mean density was $1,566ind./m^2$. The number of species and density of macrobenthic fauna decreased significantly with the mean grain size. The dominant species were the amphipods Melita denticulata (16.5%) and Melita shimizui (5.5%), polychaete Salvatoria clavata (5.4%), bivalve Glycymeris aspersa (4.4%), and ophiuroid Ophionereis dubia (4.3%). The dominant macrobenthos species on the subtidal soft-bottom differed from the coastal areas of the East Sea, suggesting that the difference in the sediment grain size affected the macrobenthos. Cluster analysis was performed to divide the study area into four groups, and environmental factors which correlated with species composition and distribution in the study area were the combination of the four parameters of salinity, dissolved oxygen, total organic carbon and depth. A future seasonal investigation is needed to understand the species composition and characteristics of the Dokdo macrobenthos.

• Clean Technology
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• v.25 no.2
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• pp.168-176
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• 2019

Spent coffee is one of biomass sources to be converted into bio-oil. However, the bio-oil should be further upgraded to achieve a higher quality bio-oil because of its high oxygen content. Deoxygenation under hydrotreating using different catalysts (catalytic hydrodeoxygenation; HDO) is considered as one of the promising methods for upgrading bio-oil from pyrolysis by removal of O-containing groups. In this study, the HDO of spent coffee bio-oil, which was collected from fast pyrolysis of spent coffee ($460^{\circ}C$, $2.0{\times}U_{mf}$), was carried out in an autoclave. The product yields were 72.16 ~ 96.76 wt% of bio-oil, 0 ~ 18.59 wt% of char, and 3.24 ~ 9.25 wt% of gas obtained in 30 min at temperatures between $250^{\circ}C$ and $350^{\circ}C$ and pressure in the range of 3 to 9 bar. The highest yield of bio-oil of 97.13% was achieved at $250^{\circ}C$ and 3 bar, with high selectivity of D-Allose. The carbon number distribution of the bio-oil was analyzed based on the concept of simulated distillation. The $C_{12}{\sim}C_{14}$ fraction increased from 22.98 wt% to 27.30 wt%, whereas the $C_{19}{\sim}C_{26}$ fraction decreased from 24.74 wt% to 17.18 wt% with increasing reaction time. Bio-oil yields were slightly decreased when the HZSM-5 catalyst and dolomite were used. The selectivity of CO was increased at the HZSM-5 catalyst and decreased at the dolomite.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.955-960
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• 2006

Catalytic decomposition over HZSM-5 was carried out in semi-batch reactor to recover gasoline from waste plastics(HDPE). To enhance the liquid yield with a molecule range of gasoline, the properties of catalytic decomposition were investigated over a commercial Si/ZSM-5 catalyst and HZSM-5 catalysts modified with P and Mg. Optimum loadings of P and Mg on HZSM-5 were 0.5 wt% and 2.0 wt%, respectively, based on conversion and liquid yield. $NH_3-TPD$ profile indicated that strong and weak acid sites totally decreased in P loading on HZSM-5 catalyst, strong acid sites moderately decreased and weak acid sites sharply reduced in Mg loading on HZSM-5 catalyst. In the case of Si/ZSM-5 catalyst, all acid sites almost disappeared, subsequently, catalytic decomposition significantly decreased, and little liquid product was produced. When HZSM-5 catalyst was modified with P and Mg, the carbon distribution of liquid product was shifted to lower carbon number and its all components was within a molecular range of gasoline($C_5-C_{11}$). Especially, over Mg(2.0 wt%)/ZSM-5 catalyst, 55.8% of liquid yield with 100% of a molecular range of gasoline, was obtained at $400^{\circ}C$, suggesting it as a promising catalyst for recycle of waste plastics.

• Journal of Environmental Health Sciences
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• v.46 no.6
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• pp.627-635
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• 2020

Objectives: Indoor air quality has become more important aspeople spend most of their times indoors. Since students spend most of their times at home or at school, they are more likely to be exposed to indoor air pollutants. Ventilation in school classrooms can affect health and learning performance. In this study, ventilation deficiency was evaluated in school classrooms using Monte Carlo simulation. Methods: This study used sensor-based monitoring for six months to measure carbon dioxide (CO2) concentrations in classrooms in elementary, middle, and high schools. The volume of the classroom and the number of students were investigated, and the students' body surface area was used to calculate the CO2 emission rate. The distribution of ventilation rates was estimated by measured CO2 concentration and a mass-balance model using Monte Carlo simulation. Results: In the elementary, middle, and high schools, the average CO2 concentrations exceeded 1000 ppm, indicating that the ventilation rates were insufficient. The ventilation rates were deficient from July to August and in December, but showed relatively high ventilation rates in October. Forty-three percent of elementary schools, 56% of middle schools, and 62% of high schools showed insufficient ventilation rates. Conclusions: The ventilation rates calculated in elementary, middle and high schools were found to be quite insufficient. Therefore, proper management is needed to overcome the lack of ventilation and improve air quality.