• Korean Journal of Environmental Biology
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• v.33 no.1
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• pp.45-52
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• 2015

Acute toxicity tests for 5 organic solvents were conducted using Euglena agilis carter (E. agilis), a Korean domestic organism. Organic solvents decreased the growth rate of E. agilis in a dose dependent manner. The toxicity to E. agilis was increased in the order of chloroform>acetone${\geq}$ethanol${\geq}$methanol>DMSO based on $EC_{50}$ values from growth test. Organic solvents also induced cell motility and morphological changes of E. agilis. Especially significant effects on the cell swimming velocity, motility, and compactness were observed for chloroform at the concentration of $EC_{50}$ calculated from 96 hr growth test. Overall, toxic responses of E. agilis to test substances are comparable to or more sensitive than D. magna, M. macrocopa and V. fischeri. Our study demonstrates that E. agilis can be a putative ecotoxicity test model organism to assess domestic water quality. Results obtained from this study can be applied to establish the standard test guidelines for ecotoxicity test using E. agilis.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.2
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• pp.184-190
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• 2008

Various ECT techniques have been applied basically to assess the integrity of steam generator tithing in nuclear power plant. Among these techniques, the bobbin probe technique is applied generally to examine the volumetric flaws such as a crack-like defect and wear which is generally occurred on steam generator tubing, and additionally MRPC probe is used to examine closely tile top of tubesheet and bending regions due to the high possibility of cracking. Dent and bulge also may be formed on tube during installation process and operation of steam generator, but the dent and bulge indications greater than specific size criteria are recorded on examination report because these indications are not considered as flaw. These indications can be easily detected with bobbin probe and approximately sized with profile bobbin probe, but the size and shape can not be accurately verified. Accordingly, in this study, the $8{\times}1$ multi-array EC probe was designed to increase the measurement accuracy of the sectional profiling EC testing of tube. As a result, we would like to propose the application of $8{\times}1$ multi-array EC probe for the measurement of size and shape of profile change on steam generator tube in OPR-1000 nuclear power plant.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.109-115
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• 2006

Understanding characteristics of claypan soils has long been an issue for researchers and farmers because the high-clay subsoil has a pronounced effect on grain crop productivity. The claypan restricts water infiltration and storage within the crop root zone, but these effects are not uniform within fields. Conventional techniques of identifying claypan soil characteristics require manual probing and analysis which can be quite expensive; an expense most farmers are unwilling to pay. On the other hand, farmers would be very interested if this information could be obtained with easy-to-use field sensors. Two examples of sensors that show promise for helping in claypan soil characterization are soil profile strength sensing and bulk soil apparent electrical conductivity (ECa). Little has been reported on claypan soils relating the combined information from these two sensors with grain crop yield. The objective of this research was to identify the relationships of sensed profile soil strength and soil EC with nine years of crop yield (maize and soybean) from a claypan soil field in central Missouri. A multiple-probe (five probes on 19-cm spacing) cone penetrometer was used to measure soil strength and an electromagnetic induction sensor was used to measure soil EC at 55 grid site locations within a 4-ha research field. Crop yields were obtained using a combine equipped with a yield monitoring system. Soil strength at the 15 to 45 cm soil depth were significantly correlated to crop yield and ECa. Estimated crop yields from apparent electrical conductivity and soil strength were validated with an independent data set. Using measurements from these two sensors, standard error rates for estimating yield ranged from 9 to 16%. In conclusion, these results showed that the sensed profile soil strength and soil EC could be used as a measure of the soil productivity for grain crop production.

• Korean Journal of Plant Resources
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• v.23 no.4
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• pp.386-392
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• 2010

This study was done to measure the color and catechins contents in processed teas using the whole bands (400~2500 nm) with near-infrared spectroscopy(NIRS). The powder colors of 109 processed teas were measured with a colorimeter. The a/b ratios in Hunter color scale in processed teas accounted for about 98.9% of the variation in the fermentation degree(FD), indicating that the a/b ratio was a very useful trait for assessing fermentation degree. Also tea powders were scanned in the visible bands used with NIRSystem. The calibration equations for powder colors were developed using the regression method of modified partial least squares(MPLS) with the internal cross validation. The equations had low SECV (standard errors of cross-validation), and high $R^2$ (coefficient of determination in calibration) values with 0.996~1.00, indicating that the visible bands(400~700 nm) with NIRS could be used to rapidly measure the variables related to powder color and fermentation degree. Also another powders of 137 processed teas were scanned at 780~2500 nm bands in the reflectance mode. The calibration equations were developed using the regression method of MPLS with the internal cross validation. The equations had low SECV, and high $R^2$ (0.896~0.983) values, showing that NIRS could be used to rapidly discriminate the contents of EGC($R^2$=0.919), EC(0.896), EGCg(0.978), ECg(0.905) and total catechins(0.983) in processed teas with high precision and ease.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.5
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• pp.414-422
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• 1984

This research was conducted to evaluate the effect of polluted Oncheon Stream on the marine organisms in the Suyeong Bay. Water quality and 96 hr acute toxicity to the sea urchin, Hemicentrotns pulcherrimus by recirculation bioassay were examined from Feb. 20 to Apr. 15, 1984. The 96 hr $50\%$ effective concentration($EC_{50}$) on the attachment of the podia of the sea urchin was observed to occur at test concentrations between 40.0 and $51.0\%$ (v/v), and safe concentrations may be assumed to be within 4.0 and $5.1\%$. These values indicate as follows : 1. Oncheon Stream was extremely polluted by oxygen-demanding wastes and synthetic organic compounds from sewage and industrial waste water. 2. Linear alkylbenzene sulfonate(LAS) which has not been yet included in water quality standard was discharged above the TLm. 3. Unknown toxicity may be synergy among complex substances. In consideration of the relationship between COD values of Oncheon Stream and dilution water, the effect of toxicity of Oncheon Stream water reached to the area of the Suyeong Bay where the COD value was found to be 12.2 ppm.

• Journal of Korean Society of Steel Construction
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• v.25 no.2
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• pp.131-139
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• 2013

The object of this paper is to perform the experiments to investigate the relationship of the resistance forces and the failure temperatures on the failure behaviors of H-shaped steel compressive members. H-shaped members(SS400) were used for the test models and the tests for the elevated temperatures were performed by ISO 834 in FILK(Fire Insurers Laboratories of Korea). The local, overall buckling stresses and a yielding stresses for the failure temperatures were compared with the compressive stresses for the loading forces of test models, the yielding strength and elastic modulus reduction factor of the steel at a high temperature were based on the criteria of the EC3(Eurocode 3) Part1.2(1993). The slenderness ratio was fixed by 45.4 and the compressive forces corresponded with 50%, 70% and 80% of the yielding forces at the normal temperatures were chosen for the loading forces of the test models. The failure temperatures of the test models were investigated under three kinds of loading conditions. It was known that the resistance forces have come close to the yielding forces, not the elastic buckling loads evaluated by EC3 at the failure temperatures obtained from the tests which are related to the failure temperatures and the loading stresses.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.466-471
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• 2019

1,4-dioxane and dichloromethane are classified as carcinogenic groups in the International Agency for Research on Cancer (IARC). They are frequently released at high concentrations in an industrial wastewater effluent. The acute toxicity (24 h) of Daphnia magna for 7.53 mg/L of 1,4-dioxane in the industrial effluent was evaluated as 1.1 TU (toxic unit) and showed TU close to the effluent quality standard. Mixed substances of 1,4-dioxane and dichloromethane in the industrial effluent showed relatively high TU as compared to that of a single substance. Half maximal effective concentration (24 h $EC_{50}$) values of 1,4-dioxane and dichloromethane for the synthetic wastewater prepared in laboratory were 1,744 (0.06 TU) and 170 mg/L (0.6 TU), respectively and the toxicity was low. Nevertheless the toxicological evaluation of the mixture showed that TU values increased to 0.02, 0.04 and 0.10, respectively as 1, 5 and 10 ppm of dichloromethane was added to 100 ppm of 1,4-dioxane. And the synergistic effect was observed between two substances. But the TU value of synthetic wastewater was below 5%, lower than that of industrial effluent at the similar concentration.

• Land and Housing Review
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• v.13 no.1
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• pp.131-140
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• 2022

A smart window is a new building material that can realize energy savings in a building. Smart windows can freely adjust Visible Light Transmittance (VLT) and solar gain coefficient (g-value) according to the situation. Smart windows include such technologies as Electrochromic (EC), Suspended Particle Device (SPD), and Polymer Dispersed Liquid Crystal (PDLC). Recent research on building energy savings through the VLT and g-value control functions of smart windows is being actively conducted and meaningful results are being drawn. However, since most of the research is focused on energy savings, research on the indoor environment is somewhat lacking. A building is a space where people live and the comfort of life should be prioritized before energy savings. Therefore, in this study, analysis on the daylight performance of an office space was carried out. Through green building standards such as LEED, BREEAM, CASBEE, and G-SEED, the daylight performance was reviewed according to VLT value changes of the smart window. In addition, a study was conducted on the VLT range of the electrochromic façade that can maintain a comfortable indoor environment. The smart window used electrochromic control with a wide range of VLT. The study showed that the minimum VLT of a smart window that can satisfy G-SEED is 25% or more. In addition, it was found that the VLT change of the electrochromic smart window did not significantly affect the uniformity of the room. When the LEED standard was applied, the minimum VLT value of the electrochromic smart window that must be maintained according to each orientation of the building was derived.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.3
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• pp.269-286
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• 2015

24-hr integrated $PM_{2.5}$ measurements were performed between December 2013 and October 2014 at an urban site in Gwangju and the collected samples were analyzed for organic carbon (OC), elemental carbon (EC), ionic species, and elemental species. Objectives of this study were to identify $PM_{2.5}$ pollution episodes, to characterize their chemical components, and to examine their probable origins. Over the course of the study period, average $PM_{2.5}$ concentration was $37.7{\pm}23.6$ $(6.0{\sim}121.5){\mu}g/m^3$. Concentrations of secondary ionic species; $NH_4{^+}$, $NO_3{^-}$, and $SO_4{^{2-}}$ was on average $5.54{\mu}g/m^3$ (0.28~ 20.86), $7.60{\mu}g/m^3$ (0.45~ 33.53), and $9.05{\mu}g/m^3$ (0.50~ 34.98), accounting for 13.7% (4.6~ 22.7), 18.6% (2.9~ 44.8), and 22.9% (4.9~ 55.1) of the $PM_{2.5}$ concentration, respectively. Average OC and EC concentrations were $5.22{\mu}g/m^3$ and $1.54{\mu}g/m^3$, taking possession of 4.6 and 22.2% (as organic mass) of the $PM_{2.5}$, respectively. Frequencies at which 24-hr averaged $PM_{2.5}$ exceeded a 24-hr averaged Korean $PM_{2.5}$ standard of $50{\mu}g/m^3$ (termed as an "episode" in this study) were 30, accounting for 21.3% of total 141 measurements. These pollution episodes were mostly associated with haze phenomenon and weak surface wind speed. It is suggested that secondary formation of aerosol was one important formation mechanism of the episodes. The episodes were associated with enhancements of organic mass, $NO_3{^-}$ and $SO_4{^{2-}}$ in winter, of $NO_3{^-}$ and $SO_4{^{2-}}$ in spring, and of $SO_4{^{2-}}$ in summer. Potential source contribution function results indicate also that $PM_{2.5}$ episodes were likely attributed to local and regional haze pollution transported from northeastern China in winter, to atmospheric processing of local emissions rather than long-range transport of air pollutants in spring, and to the $SO_4{^{2-}}$ driven by photochemistry of $SO_2$ in summer.

• Journal of Wetlands Research
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• v.9 no.1
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• pp.21-29
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• 2007

In Korea, we assign the chemical substances of 535 types as toxic substance. Only 10% of the 535 toxic substances are being managed by the Ministry of Environment related with water quality standard. Tar color is also one of chemical substances, but we have the lacks for the information of tar colors about the environmental effects of aquatic ecosystem. This study performed the test of bioassay using Water Fleas and Luminescent Bacteria. The tar has 7 types of colors allowed as the edible color and we evaluate the toxicities of 5 tar colors out of 7 colors and we would like to provide the informations for further study as we perform the toxicity test for the samples of 5 tar colors. We did the toxicity test of using Water Fleas From the results, we obtained the magnitudes of toxicity in order of Red No.2, Yellow No.5, Red No.3, Yellow No.4, Blue No.1. As the result based on Microtox Acute Toxicity Test using Luminescent Bacteria with the standard of 15min-EC50, we obtained in order of Yellow No.5, Food Red No.3, Red No.2, Yellow No.4, Blue No.1. We could expect the tar colors may have different effects on the aquatic ecosystem, respectively and it may influence to the aquatic ecosystem and the human, because of bioconcentration by food chain when toxicity of the tar colors overflow in the aquatic ecosystem.