• Economic and Environmental Geology
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• v.43 no.3
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• pp.269-278
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• 2010

We investigated characteristics of the coloring material of Dancheong pigments and hope that this study contributes the revival of traditional Dancheong pigments color. For this purpose, we collected Dancheong fragment samples that fell off naturally from old wooden buildings in Gwangju and Jeonnam and analyzed the natural coloring material by XRD and EDS-SEM analysis method. In white pigments of Dancheong fragments, it is confirmed that gypsum$(CaSO_{4}{\cdot}2H_{2}O)$, quartz$(SiO_{2})$, white lead$(PbCO_{3})$ and calcite$(CaCO_{3})$ which have been used for white pigments since ancient times and $TiO_{2}$ which is common used in modern times. In red pigments of Dancheong fragments, it is confirmed that hematite$(Fe_{2}O_{3})$ and red lead$(Pb_{3}O_{4})$, which have been used for red pigments since ancient times and C.I. pigment orange $13(C_{32}H_{24}C_{12}N_{8}O_{2})$ but there is no cinnabar(HgS) which has been used since B.C. 3000 in China. In yellow pigments of Dancheong fragments, it is confirmed that crocoite$(PbCrO_{4})$ and massicot(PbO). In blue pigments of Dancheong fragments, it is confirmed that sodalite$(Na_{4}BeAlSi_{4}O_{12}Cl)$ and nosean $(Na_{8}Al_{6}Si_{6}O_{24}SO_{4})$ as coloring material of blue pigment and C.I. pigments blue $29(Na_{7}Al_{6}Si_{6}O_{24}S_{3})$ which is used in modern times. In green pigments of Dancheong fragments, it is confirmed that calumetite$(Cu(OHCI)_{2}{\cdot}2H_{2}O)$, escolaite(Cr2O3), dichromium trioxide$(Cr_{2}O_{3})$, emerald green$(C_{2}H_{3}As_{3}Cu_{2}O_{8})$, and C.I. pigments green$(C_{32}H_{16}-XCl_{x}Cu_{8})$ which is used in modern time. In black pigments of Dancheong fragments, Chiness ink(carbon black) is confirmed.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.396-404
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• 2011

An investigation on the removals of PAH-quinone compounds, which are commonly produced from the biological and/or chemical treatments of PAH-contaminated soils, from the aqueous phase via birnessite (${\delta}-MnO_2$)-mediated oxidative transformation is described. It was demonstrated that acenaphthenequinone (APQ), p-PAH quinone can be removed via birnessite-mediated oxidative-coupling reactions, and anthraquinone (AQ) and 1,4-naphthoquinone (1,4-NPQ), o-PAH quinones were efficiently removed by birnessite-mediated cross-coupling reactions in the presence of catechol (CAT) as a reactive mediator. The removals of PAH-quinone compounds followed pseudo-first-order reactions, and the rate constant (k, $hr^{-1}$) for the removals of 1,4-NPQ under the experiment conditions (1,4-NPQ = 10 mg/L, CAT = 50 mg/L, ${\delta}-MnO_2$ = 1.0 g/L, pH 5, Reaction time = 6~96 hr) was 0.0426, which was about 4 times lower than that of APQ (0.173). With the observed pseudo-first order rate constants with respect to birnessite loadings under the same experimental conditions, the surface-normalized specific rate constant, $K_{surf}$, for 1,4-NPQ was determined to be $8.5{\times}10^{-4}L/m^2{\cdot}hr$. The analysis of the kinetic data with respect to birnessite loading indicated that the cross-coupling reactions of 1,4-NPQ consist of two different reaction steps over time and the results have also been discussed in terms of the reaction mechanisms.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.279-289
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• 2000

The objective of this study was to investigate the effect of coagulants and solid-liquid separation methods on algal removal in water treatment processes. Thus characterization of raw water quality in terms of turbidity. UV-254, $KMnO_4$ consumption, chlorophyll-a and correlation analysis of these parameters were conducted. In addition, the effect of commercial Al-based coagulants(Alum. PAC and PACS) on algal removal was studied by turbidity and organic removal, algal species removal, characteristic of pH drop and alkalinity consumption using laboratory jar tests. Organic components including UV-254, $KMnO_4$ consumption, chlorophyll-a in case of algal bloom were highly correlated with turbidity and the correlation coefficients of UV-254, $KMnO_4$ consumption, chlorophyll-a with turbidity were 0.775, 0674 and 0.623, respectively. In coagulation and sedimentation, the Al-based coagulants showed similar efficiency of organic and turbidity removal in low organic($KMnO_4$ consumption below 15mg/l) and low turbidity(below 30NTU). However, PAC and PACS showed better algal removal than alum in high organic concentration($KMnO_4$ consumption above 20mg/l) and high turbidity(above 100NTU) raw water conditions generated by high algal growth, which is considered to be due to the floc settleability. In comparison of sedimentation and flotation after chemical coagulation and flocculation, the removal efficiency of organic and turbidity were higher in case of alum dose with flotation than with sedimentation, while those were better in case or PAC and PACS with sedimentation than with flotation. Thus, Alum with flotation and PAC and PACS with sedimentation is recommended for efficient algal removal. The dominant phytoplankton in raw water were Microcystic and pediastrum simplex and the removal efficiency of algae with sedimentation using alum. PAC and PACS were 27%, 45% and 22% respectively, while those with DAF showed 100% removal of phytoplankton and zooplankton.

• Korean Journal of Construction Engineering and Management
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• v.15 no.5
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• pp.82-93
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• 2014

Long Term rental housing, which is supplied for performing housing welfare, has been aging from permanent rental housing. Therefore, variety housing welfare projects are planing and performing for improving aged facilities. However, although every welfare policy are necessary, we have to efficiently allocate and commit the funds, because the fund and resources is limited. And there is required the feasibility study before performing public project for housing welfare, because it needs large amount of financial supports by government. Meanwhile, because most of existed studies are focused on guide development, it has limitation to apply the result of existed studies in this study, which considers public remodeling project for housing welfare. But in reality, public project is been decided by willing of policy decision-maker. Therefore, in this study, we suggest the evaluation method of policy value for two alternatives(remodeling and maintain) of a aged long term rental housing. To extract the attributes of policy value, we considered categorized items of preliminary feasibility study. Through extracting attribute factors of policy value for aged long term rental housing, we can calculate the policy value of remodeling and maintain alternatives by using MAUT. As a result of analysis, we can find that the utility value of remodeling is 0.6161 and the utility value of maintain is 0.2461 and also the utility of remodeling is higher than utility of maintain. Therefore, when we plan the public projects for performing housing welfare, we can choose remodeling alternative rather than maintain alternative using quantitive data.

• Restorative Dentistry and Endodontics
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• v.36 no.6
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• pp.498-505
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• 2011

Objectives: The purpose of this in vivo study was to investigate the microbial diversity in symptomatic and asymptomatic canals with primary endodontic infections by using GS FLX Titanium pyrosequencing. Materials and Methods: Sequencing was performed on 6 teeth (symptomatic, n = 3; asymptomatic, n = 3) with primary endodontic infections. Amplicons from hypervariable region of the small-subunit ribosomal RNA gene were generated by polymerized chain reaction (PCR), and sequenced by means of the GS FLX Titanium pyrosequencing. Results: On average, 10,639 and 45,455 16S rRNA sequences for asymptomatic and symptomatic teeth were obtained, respectively. Based on Ribosomal Database Project Classifier analysis, pyrosequencing identified the 141 bacterial genera in 13 phyla. The vast majority of sequences belonged to one of the seven phyla: Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, Proteobacteria, Spirochetes, and Synergistetes. In genus level, Pyramidobacter, Streptococcus, and Leptotrichia constituted about 50% of microbial profile in asymptomatic teeth, whereas Neisseria, Propionibacterium, and Tessaracoccus were frequently found in symptomatic teeth (69%). Grouping the sequences in operational taxonomic units (3%) yielded 450 and 1,997 species level phylotypes in asymptomatic and symptomatic teeth, respectively. The total bacteria counts were significantly higher in symptomatic teeth than that of asymptomatic teeth (p < 0.05). Conclusions: GS FLX Titanium pyrosequencing could reveal a previously unidentified high bacterial diversity in primary endodontic infections.

• Korean Journal of Environment and Ecology
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• v.26 no.5
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• pp.694-706
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• 2012

The purpose of this study was to offer the raw data for conservation and restoration of aquatic ecosystem by surveying and analysing a water quality, sediment, benthic macroinvertebrate, fish and hydrophyte in Junam reservoir. In the result of analysing the water quality, pH was 8.2~8.4, 6.0~7.5mg/${\ell}$ in COD, 10.0~10.3mg/${\ell}$ in SS, 8.3~11.5mg/${\ell}$ in DO, 0.1mg/${\ell}$ in T-P and 1.2~1.3mg/${\ell}$ in T-N. In case of the sediments, Cd was 0.47~0.52mg/kg, 7.08~7.43mg/kg in Cu, 0.22~0.32mg/kg in As, 0.02~0.03mg/kg in Hg, 6.20~7.45mg/kg in Pb, 32.80~39.70mg/kg in Ni, 513.0~543.0mg/kg in F and 137.0~140.0mg/kg in Zn. $Cr^{6+}$ was not detected. The benthic macroinvertebrates were 432 individuals including 3 phyla, 5 classes, 9 orders, 26 families, 33 genera and 39 species, and the ecological score of benthic macroinvertebrate community(ESB) was 25. The fishes were 8 families and 14 species, and the invasive alien species were 2 taxa including Micropterus salmoids and Lepomis macrochirus. The hydrophytes were 63 taxa including 28 families, 42 genera, 56 species, 1 subspecies and 6 varieties. The emergent plants were 38 taxa(60.3%), 5 taxa(7.9%) in floating-leaved plants and each 10 taxa(15.9%) in free-floating plants and submerged plants.

• Journal of Life Science
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• v.23 no.6
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• pp.796-803
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• 2013

Property changes and bacterial characterizations by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) were investigated during the fermentation of Makgeollies by 5 isolated yeast strains. Changes of pH were large between day 0 (pH 6) and day 2 (pH 3) and showed less variation after then. ANOVA analyses revealed that pHs were statistically different with fermentation times (p<0.001), while strains (p=0.60) did not. Acidities were changed from 0.19 to 1.04% and showed rather high increase from day 2, and fermentation times (p<0.001) and strains (p=0.006) represented statistical differences. All strains showed less than 0.150% at amino-type nitrogen contents except S strain showed 0.442% at day 8, and there were no statistical differences with fermentation times (p=0.4558) and strains (p=0.3513). Saccharinities of C strain were higher from day 4, and fermentation times (p<0.0001) and strains (p=0.007) showed statistical differences. Large variation of alcohol concentrations (%) were observed between day 0 (0%) and day 2 (10%) and showed less variation after day 2, and there was no statistical difference with strains. Dominant prokaryotes were Lactobacillus fermentum and Pediococcus pentosaceus, which producing acids and functional materials. Dominant eukaryote was Saccharomyces cerevisiae, which might be resulted from addition of yeasts.

• Korean Journal of Construction Engineering and Management
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• v.21 no.2
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• pp.59-69
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• 2020

The regulation of business area was abolished to improve the competitiveness of the construction industry and the ability of general and specialty contractors to enter the mutual market. As the next step, the government is preparing for a reorganization of business type. If the impact of the abolishing of business area on the construction industry is analyzed, the result can contribute to determining the step by step application scope of the reorganization of business type. This study derived the business types having a high probability of the mutual market entry of general and specialty contractors. Then, the size of mutual market entry is analyzed. First, the connection between the general and specialty construction, and the similarities between the registration standards of general and specialty construction are analyzed. Based on the result, a general contractor can enter 15 business types of specialty construction, and the market size is about 78.8 trillion KRW. This is about 82% of the total contract cost of specialty construction during the year 2017 (about 96 trillion KRW). Next, based on the relevance of business contents, the market size when general contractors enter the specialty construction market is analyzed. As a result, the market size is about 24.7 trillion KRW, and this is about 13% of total contract cost of general construction during the year 2017 (about 190 trillion KRW). Based on the result of this study, there is a higher probability of the mutual market entry of general contractors into specialty construction than vice versa. However, the result of this study is based on the current contents of business types, registration standards, and construction data of before abolishing the regulation of business area. This is a research limitation. If the business contents and registration standards are changed in the future, the result could differ from the current result.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.1
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• pp.1-10
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• 2018

Recently, there has been rapid development in the field of flexible electronic devices, such as organic light emitting diodes (OLEDs), organic solar cells and flexible sensors. Encapsulation process is added to protect the flexible electronic devices from exposure to oxygen and moisture in the air. Using numerical simulation, we investigated the effects of the encapsulation layer on mechanical stability of the silicon chip, especially the fracture performance of center crack in multi-layer package for various loading condition. The multi-layer package is categorized in two type - a wide chip model in which the chip has a large width and encapsulation layer covers only the chip, and a narrow chip model in which the chip covers both the substrate and the chip with smaller width than the substrate. In the wide chip model where the external load acts directly on the chip, the encapsulation layer with high stiffness enhanced the crack resistance of the film chip as the thickness of the encapsulation layer increased regardless of loading conditions. In contrast, the encapsulation layer with high stiffness reduced the crack resistance of the film chip in the narrow chip model for the case of external tensile strain loading. This is because the external load is transferred to the chip through the encapsulation layer and the small load acts on the chip for the weak encapsulation layer in the narrow chip model. When the bending moment acts on the narrow model, thin encapsulation layer and thick encapsulation layer show the opposite results since the neutral axis is moving toward the chip with a crack and load acting on chip decreases consequently as the thickness of encapsulation layer increases. The present study is expected to provide practical design guidance to enhance the durability and fracture performance of the silicon chip in the multilayer package with encapsulation layer.

• Journal of the Korean Electrochemical Society
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• v.18 no.1
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• pp.7-16
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• 2015

Effects of chemical composition ($Cu^{2+}$, $K_4P_2O_7$ and additive concentrations) of baths on properties of Cu thin films electrodeposited from pyrophosphate copper bath were investigated. Current efficiency was increased to be near 100% with increasing $Cu^{2+}$ concentrations from 0.02 to 0.3M. Decrease of current efficiency was observed in the range of 1.5~1.8M $K_4P_2O_7$ concentration, but current efficiency of about 100% was measured in the ranges of both 0.9~1.3M and 2.1~2.4M. The change of additive concentration did not influenced current efficiency. Residual stress of electrodeposited Cu thin films was measured to be about 20 MPa below 0.15 M $Cu^{2+}$ concentration and increased with the increase of it to 0.25 M. Maximum residual stress of 120MPa was observed at 0.25M $Cu^{2+}$ concentration. On the other hand, residual stress decreased from 80 to near 0 MPa as $K_4P_2O_7$ concentration varied from 0.9 to 2.4M and but The change of additive concentration did not affected on residual stress. $Cu^{2+}$ and $K_4P_2O_7$ concentrations significantly affect on surface morphology of electrodeposited Cu thin films, but additive concentration slightly affected. From XRD analysis, the microstructures of electrodeposited Cu thin film was affected from the changes of $Cu^{2+}$ and $K_4P_2O_7$ concentrations, but not from that of additive concentration. Strong preferred orientation of (111) peak was observed with increasing $Cu^{2+}$ and $K_4P_2O_7$ concentrations.