• Journal of Korean Society of Environmental Engineers
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• v.37 no.12
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• pp.696-704
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• 2015

This study was carried out to evaluate the optimum operational condition of Semi-continuously Fed and Mixed Reactor (SCFMR) to treat the dairy cow manure and saw dust mixture. Step-wise increase in organic loading rates (OLRs) or decrease in hydraulic retention times (HRTs) were utilized until the biogas volume became significantly decreased at mesophilic temperature ($35^{\circ}C$). The optimum operating condition of the SCFMR fed with TS 13% dairy cow manure and saw dust mixture was found to be an HRTs of 25 days and its corresponding OLRs of $4.45kg\;VS/m^3-day$. At this condition the biogas and methane production rates were 1.44 v/v-d and 1.12 v/v-d (volume of biogas per volume of reactor per day), respectively and the TVS removal efficiency of 37% was achieved. The successful operation with such a high OLR was due to the high reactor alkalinity concentration of 14,500~15,600 mg/L as $CaCO_3$ as a result of the characteristic of the original substrate, dairy cow manure and saw dust mixture whose alkalinity was more than 8,000 mg/L as $CaCO_3$. The parameters for the reactor stability, the ratios of volatile acids and alkalinity concentrations (V/A) and the ratio of propionic acid and acetic acid concentrations (P/A) appeared to be 0.11 and 0.43, respectively, that were greatly stable in operation. Free ammonia toxicity was not experienced due to the long term acclimation by the reactor TS content ranged 7.2~10.4% during the entire operational period.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.495-505
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• 2006

In order to classify aerosol type, Aerosol Optical Thickness (AOT) and Fine mode Fraction (FF), which is the optical thickness ratio of small particles$(<1{\mu}m)$ to total particles, data from MODIS (MODerate Imaging Spectraradiometer) aerosol products were analyzed over North-East Asia during one year period of 2005. A study area was in the ocean region of $20^{\circ}N\sim50^{\circ}N$ and $110^{\circ}E\simt50^{\circ}E$. Three main atmospheric aerosols such as dust, sea-salt, and pollution can be classified by using the relationship between AOT and FF. Dust aerosol has frequently observed over the study area with relatively high aerosol loading (AOT>0.3) of large particles (FF<0.65) and its contribution to total AOT in spring was up to 24.0%. Pollution aerosol, which is originated from anthropogenic sources as well as a natural process like biomass burning, has observed in the regime of high FF (>0.65) with wide AOT variation. Average pollution AOT was $0.31{\pm}0.05$ and its contribution to total AOT was 79.8% in summer. Characteristic of sea-salt aerosol was identified with low AOT (<0.3), almost below 0.1, and slightly higher FF than dust and lower FF than pollution. Seasonal analysis results show that maximum AOT $(0.33{\pm}0.11)$ with FF $(0.66{\pm}0.21)$ in spring and minimum AOT $(0.19{\pm}0.05)$, FF $(0.60{\pm}0.14)$ in fall were observed in the study area. Spatial characteristic was that AOT increasing trend is observed as closing to the eastern part of China due to transport of aerosols from China by the prevailing westerlies.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.3
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• pp.21-36
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• 2023

As a solution to environmental issues, such as climate change response, the carbon neutrality strategy, urban heat islands, fine dust, and biodiversity enhancement, the value of urban green spaces and trees are becoming important, and various studies dealing with the effects of trees for environmental improvement are being conducted. This study comprehensively considers the preceding studies on planting tree species, planting structure, planting density, and planting base to propose a direction for the planting renewal of green areas in urban parks and applies the findings to a renewal plan to improve the urban environment through landscaping trees. A field survey was conducted on the planting status of Seoul Children's Grand Park, a large-scale neighborhood park in Seoul, and based on the survey data, a planting function evaluation was conducted, and areas needing improvement in planting function were identified. The planting function evaluation was carried out considering the park function setting, planting concept according to spatial function, and planting status. As a result of the study, the direction of planting renewal according to functional change was derived for each stage of planting function evaluation. Increasing the green area ratio is a priority in setting up park functions, but user convenience should also be considered. As a concept of planting, visual landscape planting involves planting species with beautiful tree shapes, high carbon absorption, and fine dust reduction effects. Ecological landscape planting should create a multi-layered planting site on a slope. Buffer planting should be created as multi-layered forests to improve carbon absorption and fine dust reduction effects. Green planting should consist of broad-leaved trees and herbaceous layers and aim for the natural planting of herbaceous species. For plant species, species with high urban environment improvement effects, local native species, and wild bird preferred species should be selected. As for the planting structure, landscape planting sites and green planting sites should be composed of trees, shrubs, and trees and herbaceous layers that emphasize ecology or require multi-layered buffer functions. A higher standard is applied based on the planting interval for planting density. Installing a rainwater recycling facility and using soil loam for the planting base improves performance. The results of this study are meaningful in that they can be applied to derive areas needing functional improvement by performing planting function evaluation when planning planting renewal of aging urban parks and can suggest renewal directions that reflect the paradigm of functional change of created green areas.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.335-338
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• 2012

We present the $18{\mu}m$ luminosity function (LF) of galaxies at 0.006 < z < 0.8 (the average redshift is ~ 0.04) using the AKARI mid-infrared All-Sky Survey catalogue. We have selected 243 galaxies at $18{\mu}m$ from the Sloan Digital Sky Survey (SDSS) spectroscopic region. These galaxies then have been classified into five types; Seyfert 1 galaxies (Sy1, including quasars), Seyfert 2 galaxies (Sy2), low ionization narrow emission line galaxies (LINER), galaxies that are likely to contain both star formation and Active Galactic Nuclei (AGN) activities (composites), and star forming galaxies (SF) using optical emission lines such as the line width of $H{\alpha}$ or the emission line ratios of [OIII]/$H{\beta}$ and [NII]/$H{\alpha}$. As a result of constructing the LF of Sy1 and Sy2, we found the following results; (i) the number density ratio of Sy2 to Sy1 is $1.64{\pm}0.37$, larger than the results obtained from optical LF and (ii) the fraction of Sy2 in the entire AGN population may decrease with $18{\mu}m$ luminosity. These results suggest that most of the AGNs in the local universe are obscured by dust and the torus structure probably depends on the mid-infrared luminosity.

• Carbon letters
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• v.26
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• pp.18-24
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• 2018

Pollution of chloride ion-reinforced concrete can trigger active corrosion processes that reduce the useful life of structures. Multifunctional materials used as a counter-electrode by electrochemical techniques have been used to rehabilitate contaminated concrete. Cement-based pastes added to carbonaceous material, fibers or dust, have been used as an anode in the non-destructive Electrochemical Chloride Extraction (ECE) technique. We studied the performance of the addition of Carbon Fiber (CF) in a cement-graphite powder base paste used as an anode in ECE of concretes contaminated with chlorides from the preparation of the mixture. The experimental parameters were: 2.3% of free chlorides, 21 days of ECE application, a Carbon Fiber Volume Fraction (CFVF) of 0.1, 0.3, 0.6, 0.9%, a lithium borate alkaline electrolyte, a current density of $4.0A/m^2$ and a cement/graphite ratio of 1.0 for the paste. The efficiency of the ECE in the traditional technique using metal mesh as an anode was 77.6% and for CFVF of 0.9% it was 90.4%, with a tendency to increase to higher percentages of the CFVF in the conductive cement-graphite paste, keeping the pH stable and achieving a homogeneous ECE in the mass of the concrete contaminated with chlorides.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.65.2-65.2
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• 2013

We present a study of outflows on 24 embedded young stellar objects (YSOs), which are selected from the sources of the Dust, Ice, and Gas in Time (DIGIT) Herschel key program. Molecular outflow activity, which is believed to have strong dependence on accretion process, is the most powerful in the early embedded phase of star formation and declines as the central protostars evolve to the main sequence stage. In order to study the relation between the CO outflow observed in low J transitions and the properties of protostars, we mapped the CO outows of the selected targets in J = 1-0 and J = 2-1 lines with the 14-m TRAO telescope and the 6-m SRAO telescope, respectively. We estimate CO outflow momentum fluxes (Fco) and compare with bolometric luminosity, Lbol, bolometric temperature, Tbol, and the FIR molecular line luminosities of CO, $H_2O$, OH and [O I], which were detected by the Herschel-PACS observations. We found that $Fco_{1-0}$ is greater than $Fco_{2-1}$, and the mean ratio is about 2. L1455-IRS3 and IRAM04191 have high Fco in spite of low $L_{bol}$. The well known correlation between Fco and $L_{bol}$. is not very evident from all our samples. However, Fco and $L_{bol}$. show a rather strong correlation if L1455-IRS3 and IRAM04191 are excluded. Fco shows little correlation with FIR line luminosities of individual species, while the total FIR line luminosity summed over CO, $H_2O$, OH, and [OI] lines seems to have some correlation. In addition, we report 22 GHz $H_2O$, and 44 GHz CH3OH maser line detections in four sources out of the 24 YSOs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.507-512
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• 2017

For manned planetary exploration, human beings are developing technologies that can permanently reside on the planet, and the basic three elements of residence, such as clothing and shelter, are required to support essential technologies in construction. In order to develop infrastructure construction technology internationally, various materials and methods such as local cementation, sulfur and aluminum have been tried. in this study, a purpose is proposed a polymer concrete construction validation technology that appropriates the conditions required for manmade exploration in order to develop construction infrastructure material technology using polymer. Concrete specimens with a 10% weight ratio polymer prepared by heating on the bottom were stabilized after 2 hours of heating, and the strength was lower than the top heating method, but the solidifying speed was 2 times faster. These results are expected to be applicable not only to construction of lunar facilities for manned exploration but also to improve the construction of infrastructures such as roads and levees to prevent dust.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.6
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• pp.923-931
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• 2013

RFID (Radio Frequency Identification), which is a kind of the electronic tag, is a wireless access device using the radio frequency for recognizing the ID information. It has a variety of application such as the bus card, gate access card, distribution industry, and management of construction materials. The performance and size of RFID depend on the penetrability, recognition ratio, memory size, multi tag recognition, external pollution dust, and exterior impact, and RFID requires the packaging to protect itself considered above factors. Recently, RFID is diversely employed to effectively manage construction materials and the RFID packaging, which is robust to the external impact, is required to attach RFID on construction materials. In this paper, we propose the construction material RFID packaging designed to be robust for the external impact and to be practicable for change of the broken RFID. For the change of RFID, we separate the cast and body of the packaging. Also, we present the detail drawing for the proposed construction material RFID packaging and implement the performance evaluation of the packaging manufactured using 3D printer.

• Safety and Health at Work
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• v.10 no.4
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• pp.437-444
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• 2019

Background: Headache/eyestrain symptoms are common health problems that people experience in daily life. Various studies have examined risk factors contributing to headache/eyestrains, and physicochemical exposure was found to be a leading risk factor in causing such symptoms. The purpose of this study was to examine the relationship of headache/eyestrain symptoms with physicochemical exposure among Korean construction workers depended on worksite. Methods: This study used data from the 4th Korean Workers Conditions Survey and selected 1,945 Korean construction workers as participants. Multivariable logistic regression analysis was used to determine the relationship. Results: Exposure to vibrations among all construction workers affected the moderate exposure group [odds ratio (OR) 1.53, 95% confidence interval (CI) 1.01-2.32], the high exposure group (OR 1.77 95%CI 1.17-2.67), and the indoor high exposure group (OR 1.61, 95%CI 1.02-2.55) and among outdoor construction workers, the moderate group (OR 6.61, 95%CI 15.4-28.48) and the high group (OR 6.61, 95%CI 1.56-27.98). When exposed to mist, dust, and fumes, the indoor high exposure group was significantly affected (OR 1.63, 95%CI 1.07-2.47). All construction workers exposed to organic solvents were affected, high exposure group (OR 1.69, 95%CI 1.15-2.49) and indoor high exposure group (OR 1.77, 95%CI 1.08-2.89). The high exposure group in all construction worker (OR 1.70, 95%CI 1.20-2.42) and the indoor high exposure group (OR 1.83, 95%CI 1.17-2.89) also were affected by secondhand smoking exposure. Conclusion: Many physicochemical exposure factors affect headache/eyestrain symptoms among construction workers, especially indoor construction workers, suggesting a deficiency in occupational hygiene and health environments at indoor construction worksites.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.6 s.113
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• pp.78-89
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• 2006

This study was conducted to analyze the planting structure and ecological characteristics of greon spaces on the grounds of e Dangjin steam power plant. To achieve these goals, we surveyed existing vegetation, plant community structure, Plant volume and growth rate. Based on e vegetation analysis, existing vegetation was classified into six types: herbaceous species $(70.54\%)$, evergreen coniferous trees $(21.17\%)$, deciduous broad-leaved trees $(5.10\%)$, deciduous coniferous trees $(1.47\%)$, shrubs $(0.12\%)$, and other types $(1.59\%)$. The coal storage, office, and playground areas were community is the natural forest area where a Pinus thunbergii / Pinus densiflora community is distributed in terms of vegetation structure, species diversity, plant volume, and growth rate. The artificial green spaces(near the coal storage, office, playground areas) had a single-layer structure. Species diversity indices of the artificial green areas were $0.1655\~0.4807$ compared to 0.8628 in the natural forest, which presented a good growth environment. Also, the plant volume in the artificial green space was lower than that of the natural green space. Therefore, it would be desirable to develope a multi-layer structure similar to that of the vegetation in the natural green space in order to improve the amount of plant volume. The plant-damage ratio of Pinus thunbergii was $52.48\%$ in the coal storage area, and $8.48\~ 11.52\%$, in the other survey areas. Also, the vitality of Pinus thunbergii was $15.45k{\Omega}$ in the coal storage areas, which indicates bad growing conditions. This suggests that soil characteristics and dust have a bad impact on growth. The investigation into deciduous tres' growth status showed that appropriate plants would be Albizzia julibrissin, Acer palmatum var. sanguineum, Acer palmatum, Malus spp., Prunus sargentii.