• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.100-107
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• 2007

People have spent lots of time inside building about 90% of these day. Industry has been developed rapidly after I960. Construction materials had changed from natural materials to chemical materials and confidentiality of building has been more higher than before by policy of saving energy. These have caused sick-building syndrome (SBS) for us. So people want environmental construction materials for their house. We designed a environmental loess (yellow soil) finishing material which was composed of loess, water, water-soluble resin, hardener and filler. The purposes of this study were that making an environmental loess finishing material with optimum ratio, evaluating the usability of loess finishing material for wall. Furthermore it was suitable for wall to evaluate mechanical properties that are impact test, cracking test, abrasion test and de-bonding test, environmental properties that were emission of VOCs, formaldehyde and far infrared radiation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.270-275
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• 2019

Mica capacitor is being adopted for high voltage firing unit of guided weapon system because of its superior impact enduring property relative to ceramic capacitor. Reliability of localized mica high voltage capacitors was verified through environmental test like terminal strength test, humidity test, thermal shock test and accelerated life test for application to high voltage firing unit. Failure mode of mica capacitor is a decrease of insulation resistance and its final dielectric breakdown. Main constants of accelerated life model were derived experimentally and voltage constant and activation energy were 5.28 and 0.805 eV respectively. Lifetime of mica capacitor at normal use condition was calculated to be 38.5 years by acceleration factor, 496, and lifetime at accelerated condition and this long lifetime confirmed that mica high voltage capacitor could be applied for firing unit.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.81-99
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• 2018

Excessive groundwater discharge by tunneling and tunnel operation can lead to groundwater exhaustion and ground subsidence. Therefore, it is very important to evaluate environmental impact and to establish mitigation measures of the impact related to tunnel excavation based on hydrogeological and modeling approaches. This study examined the depletion of surface reservoirs and valley water due to tunnel excavation through field survey, water quality analysis, tracer test, and groundwater modeling. As a result of field water quality test, the concentration of chemical constituents in groundwater discharge into the tunnel is slightly higher than that of valley water. By the result of laboratory water analysis, both valley water and the groundwater belong to $Ca^{2+}+HCO_3{^-}$ type. Tracer test that was conducted between the valley at the injection point and the tunnel, indicates valley water infiltration into the ground and flowing out to the tunnel, with maximum electrical conductance changes of $70{\mu}S/cm$ in the first test and of $40{\mu}S/cm$ in the second test. By groundwater modeling, the groundwater discharge rate into the tunnel during tunnel construction is estimated as $4,942m^3/day$ and groundwater level recovers in 3 years from the tunnel completion. As a result of particle tracking modeling, the nearest particle reaches the tunnel after 6 hours and the farthest particle reaches the tunnel after 9 hours, similarly to the case of the field trace test.

• Journal of Environmental Impact Assessment
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• v.21 no.2
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• pp.297-314
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• 2012

This study investigates the stigma effect of unwelcomed facilities on apartment prices through multiple regressions based on hedonic price method. The areas studied are Sang-gye Jugong 7, 9, 10 apartment complexes. The facilities analyzed are the Chang-dong Electric Subway Depot and the Do-bong Driver's License Agency. The factors studied include the environmental variable (the elapsed time since the announcement of the re-location of these facilities), the view commanding, the distance from Chang-dong Depot, the distance from Do-bong Driver's License Test Course, the distance from neighboring facilities (subway stations, schools, parks and so on), the floor and each dwelling's exclusive space. The data used are 2,822 sales which have been collected since January 1, 2006. The facts found are as follows; first, the view commanding and the distance from the unwelcomed facilities are statistically significant. second, the environmental variable, 'days' turns out to have a positive (+) and a negative (-) significant relationship with the dependent variable, 'price', in period II and period IV respectively. This implies that the stigma effect is real. third, there are significant differences in the influence on the apartment prices among the independent variables according to time. fourth, the stigma effect is estimated as 33,686,920 Korean won in the case of the apartments which have the view commanding and 30,311,844 won in the other case before the global economic crisis. This effect seems to decrease to 22,085,078 won after the crisis. These facts suggest that stigma effects could be considered as one of the benefits in the cost-benefit analysis of Chang-dong Depot re-location project to produce somewhat higher NPV or B/C ratio.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.654-661
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• 2017

Recently, a low-impact development (LID) technic such as a wetland has been proposed as a Nature-friendly process for reducing pollutants caused by livestock wastewater. Therefore, the Daphnia magna toxicity was analyzed for livestock wastewater samples, to determine if a wetland system would also be effective in reducing this ecotoxicity. In the present study, acute D. magna toxicity was not significantly dependent on the presence and type of reed, nor type of media. However, when treated with construction wetlands, ecotoxicities decreased as well as TN, TP and COD concentrations. Therefore, it is considered that a construction wetland system with bio reeds and bio-media as well as general reeds would be effective to reduce the ecotoxicity of livestock wastewater. To apply a wetland system as the subsequent treatment process to a livestock waste water treatment facility, it is necessary to perform an integrated evaluation such as treatment efficiency and the ecotoxicity test for various characteristics of livestock wastewater.

• Journal of Environmental Impact Assessment
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• v.32 no.5
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• pp.353-362
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• 2023

TOC, which can measure more than 90% of organic substances, can be measured quickly and easily,replacing BOD and COD, which were indicators of organic pollutants. According to water quality pollution control standards, when measuring TOC, if the inorganic carbon ratio in the sample is over 50%, the NPOC (Non-Purgeable Organic Carbon) method should be used. If volatile organic compounds (VOCs) are present at a certain concentration, the TC-IC (subtracting inorganic carbon from total carbon) method should be used. To validate the limitations of these analytical conditions, experiments were conducted by varying the ratio of TOC to IC in purified water and measuring the concentration of TOC in test solutions. The results showed no significant difference between the TC-IC method and the NPOC method. When measuring samples with added VOC standard solutions, it was observed that the carbon loss due to purging was not significant when using the NPOC method. Therefore, it is concluded that the choice of analytical method does not lead to significant differences when VOCs are present in the sample. To account for potential variations in results based on water quality pollution control standards and regulations regarding the approval and testing of environmental measurement devices, a comparison of field sample concentration values was made using two widely used types of TOC analyzers in Korea. The results showed variations of 0.02 to 0.83 mg/L between methods depending on the manufacturer, highlighting the need for caution when selecting an instrument.

• The Journal of Engineering Geology
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• v.16 no.4 s.50
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• pp.403-409
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• 2006

This study was performed to assess the clay impact on alga growth which was a primary producer, in view of food chain in ecosystem. As clay minerals caused turbidity, a low sedimentation, high adsorption capacity with organic matter, adsorption - desorption effect with ionic chemicals, clay minerals were supposed to have a significant effect on the aquatic system. In study we tried to turn out NOAEL (No-observed-adverse-effect-level) of clay materials on the algae growth inhibition using such as kaolinite, sericite and montmorillonite. This study was indicated. (1) In both of kaolinite and sericite, the $72hr-EC_{50}$ of them shows 2,752 mg/L and 2,775 mg/L, respectively. (2) On the other hand, in the case of montmorillonite, the $72hr-EC_{50}$ is not shown a significant difference to that of control samples. (3) It can be explained that is also a very important parameter in an alga growth. Because an alga growth was increased when the permeability of W visible radiation was increased in all clay cases. (4) It is demonstrated alga growth was affected by the characteristics of clay materials. Hence we can assess the $\ulcorner$water environmental risk assessment caused clay materials$\lrcorner$ using the alga growth inhibition level indirectly.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.80-86
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• 2017

BACKGROUND: Pesticides is exposed in an aquatic environment and effected to benthic animals. Especially, sediment-associated pesticides is required for determination of sediment toxicity on aquatic organisms. This study was conducted to evaluate the impact of six pesticides (chlorfluazuron, difenoconazole, dithianon, flufenoxuron, flutianil, pendimethalin) on Chironomus riparius in aquatic ecosystems. METHODS AND RESULTS: Chlorfluazuron, difenoconazole, dithianon, flufenoxuron, flutianil and pendimethalin were used as a model compounds, which have a sediment-associated potential ($K_{oc}$>3). Acute and chronic toxicity tests on Chironomus riparius were performed at six concentrations of each pesticide with four replicates of each based on OECD test guideline 235 and 218. The calculated 48-h $EC_{50}$ values of chlorfluazuron, flutianil, pendimethalin, difenoconazole, dithianon and flufenoxuron were 6.72, 2.55, 2.27, 0.77, 0.30 and 0.11 mg/L, respectively. Flufenoxuron was the lowest 48-h $EC_{50}$ value in this study. The No Observed Effective Concentration (NOEC) and the Lowest Observed Effect Concentration (LOEC) of flufenoxuron for Chironomus riparius in 28-days test were 30 and $60{\mu}g/kg$, respectively. CONCLUSION: Pesticides of the sediment-associated have the potential effect for Chironomus riparius in aquatic ecosystems. Therefore, sediment toxicity assessment of these pesticides should be further investigated to evaluate the impact to benthic organisms.

• Journal of Environmental Health Sciences
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• v.41 no.5
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• pp.299-304
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• 2015

Objectives: A people-counting system measures real-time occupancy through motion detection. Accurate people-counting can be used to calculate suitable ventilation demands. This study determined the optimum motion threshold for a people-counting system. Methods: In a closed room with two occupants moving constantly, different thresholds were tested for the accuracy of a people-counting system. The experiments were conducted at 150, 300, 450 and 600 lux. These levels of brightness included the illumination levels of most public indoor areas. The experiments were repeated with three types of clothing coloration. Results: Overall, a threshold of 16 provided the lowest mean error percentage for the people-counting system. Brightness and clothing color did not have a significant impact on the results. Conclusion: A people-counting system could be used with threshold of 16 for most indoor environments.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.742-748
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• 2019

Influence of several experimental parameters (e.g., initial dye concentration, pH, distance between electrodes, applied voltage, electrical conductivity, current density, and reaction time) on the performance of electrocoagulation (EC) process for the removal of acid blue 25 (AB25) was studied. A bipolar batch reactor was used to test the impact of the parameters. The removal efficiency (RE) of AB25 dye was promoted by increasing the contact time, voltage, electrical conductivity, and applied current density. In contrast, RE of AB25 decreased with higher level of AB25 and the longer distance between electrodes. The removal efficiency increased consistently until pH 7, but decreased above pH 7. The maximum efficiency of AB25 removal above 90% was obtained at a voltage of 60 V, reaction time of 90 min, distance between electrodes of 0.5 cm, initial concentration of 25 mg/L, conductivity of 3,000 μS/cm and pH of 7. These results imply that the high RE of AB25 dye from the aqueous solution can be achieved by EC process.