• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.11
• /
• pp.1115-1122
• /
• 2010

The main objective of this study is to experimentally investigate the effect of adhesive thickness and environmental conditions on the failure and strength of sandwich-to-laminate bonded joints. Three different adhesive thicknesses (t=0.2, 2 and 4 mm) and two different environmental conditions were considered. Environmental conditions include the RTD(room temperature and dry condition) and ETW(elevated temperature and wet condition). Test results show as the adhesive thickness increases from 0.2 mm to 2 and 4 mm, the joint strength decreases 16 and 30%, respectively. Regarding the effect of environmental conditions, except for one case, the joint strength in the ETW conditions turned out to be 12% higher than those in the RTD conditions. In the joints with adhesive thickness of 0.2 mm, remarkable difference from RTD condition was not found.

• Journal of Environmental Science International
• /
• v.11 no.10
• /
• pp.1103-1108
• /
• 2002

In order to evaluate the degradation organophosphorus pesticide, EPN, in water environment, the effects of water temp.(10$^{circ}C,\;30^{\circ}C$), pH(3-11) and sunlight on its degradation were investigated during 10 days. The degradation rate of EPN(200 rpm) was faster at higher water temp. and higher pH, i.e., its degradation rate at pH 3, 5, 7, 9, 11 was 57, 63, 66, 69, 75%(1$0^{\circ}C$), and 70, 74, 79, 91, 97%(3$0^{\circ}C$) after 10 days, respectively. The effect of water temp. on its degradation was little in acidic condition, but was rather great in alkaline condition, with time. EPN was degraded fast at the alkaline condition by photolysis. At the condition of pH 11, EPN was degraded fast at the early stage in the first 2 days, but after that the degradation rate was weakened.

• Korean Journal of Environmental Biology
• /
• v.21 no.4
• /
• pp.328-336
• /
• 2003

Biological and ecological characteristics of Diporeia spp. are described including size, growth, life cycle, energy storage, temperature effect, bioturbation, feeding depth and sediment ingestion of Diporeia. Bioaccumulation and toxicity of organic contaminants and trace metals were reviewed in addition to an examination of the relationships among various condition indexes (i.e. wet weight, dry weight and body length) of Diporeia.

• Journal of Korean Society on Water Environment
• /
• v.28 no.2
• /
• pp.213-218
• /
• 2012

Abnormal dissolved oxygen concentration in aquatic habitat, both depletion and supersaturation, can be stress factor to aquatic animals. In this study the nationwide distribution of oxygen supersaturation was analyzed for three categories of streams (43 urban streams, 15 rural streams, and 14 forest streams) by using monitoring network data of the Korean Ministry of Environment. From the distribution analysis 30% of urban streams showed hyperoxic condition of eutrophic level, while no forest stream showed hyperoxic condition. The physiological effect of hyperoxia on fish was examined using two species of fish Zacco koreanus, which resulted in higher concentration of a stress hormone (cortisol) in fish exposed to hyperoxic concentration (196%) of oxygen. This study shows that hyperoxic condition is ubiquitous in urban and rural Korean streams, and it can be a stress factor to aquatic animals.

• Journal of the Korean Geosynthetics Society
• /
• v.18 no.1
• /
• pp.79-89
• /
• 2019

The field measurement and laboratory experiment were conducted to investigate the effect of reducing the surface temperature of the functional aspect of the heat island phenomenon of the permeable block which is made the recycled synthetic resin rather than the existing concrete permeable block. Field measurement was taken for 3 days in consideration of dry condition and wet condition and laboratory experiment was divided into dry condition, rainfall simulating condition, and wetting condition. The variations of temperature and the evaporation rate of water moisture content after experiment were confirmed. As a result of field measurement, it is confirmed that the surface temperature decreases due to the difference in albedo of the pore block surface rather than the cooling effect due to the latent heat of vaporization. The evaporation of moisture in a dry state where drought persisted or a certain level of moisture was not maintained in the surface layer. As a result of laboratory experiment, resin permeable block gives higher surface temperature when it is dry condition than concrete permeable block, but the evaporation of water in the pore is kept constant by capillary force in rainfall simulation condition, and higher temperature reduction rate. As a result of measuring the evaporation rate after laboratory experiment, it is confirmed that the effect of reducing temperature is increased as the evaporation rate of water is higher. Based on these results, correlation formula for evaporation rate and temperature reduction rate is derived.

• Journal of Korean Society of Water and Wastewater
• /
• v.35 no.3
• /
• pp.227-235
• /
• 2021

This study examined the effect of ultraviolet (UV) application on bacterial disinfection in a commercialized humidifier using ultrasonic wave (UW). To accurately examine disinfection kinetics in tap-water condition, tap-water was sterilized using a filter, and then inoculated with pure cultures of E. coli and P. putida with known viable counts. The disinfection kinetic characteristics were experimentally compared when UV alone, UW alone, and UW+UV together were applied in disinfecting the added bacteria in the commercialized humidifier. When UV alone was applied, bacterial disinfection kinetics followed a first-order decay reaction, and showed an approximately 10-time weaker disinfection compared to the typical UV disinfection in water treatment or wastewater treatment. When UW alone was applied, bacterial disinfection kinetics followed a second-order decay reaction with a low disinfection rate constant of 0.0002 min^-1(CFU/mL)^-1. When UV and UW were applied together, however and interestingly, the disinfection rate constant (0.0211 min^-1(CFU/mL)^-1) was approximately 100 times increased than that for the UW alone case. These results revealed that the co-use of UV and UW can provide synergistic effect on bacterial disinfection in a tap-water condition in household humidifiers.

• Journal of Environmental Science International
• /
• v.6 no.2
• /
• pp.113-124
• /
• 1997

The basic mechanism of the granular sludge formation which is the most important factor in the start-up and stable operators is not confirmed yet. In this study, the effect of granular sludge formation was investigated with the different substrate concentrations and the various ratios of substrate supply/deficiency. The granular sludge formation in the UASB reactor was closely related to the substrate concentrations and the ratio of substrate supply/deficlency The granular sludge formation was not accelerated at low substrate concentration. It was convinced that granular sludge formation was accelerated when the substrate supply with high concentration was stopped at UASB reactor. From this experiment, it was estimated that granular sludge was formed by the combination of hydrogen utilizing bacteria that form hydrogen condition and acid forming bacteria at substrate deficit condition by mutual symbiosis. Though the removal efficiency of organic matter was decreased as the influent substrate concentration was Increased, the higher the influent substrate the better the granular sludge formation.

• Advances in environmental research
• /
• v.3 no.2
• /
• pp.151-162
• /
• 2014

Among the combination of 4 different second metals and 3 different noble metals, Ni 10%-Pd 1%/hematite (Ni(10)-Pd(1)/H) showed best tetrachloroethylene (PCE) removal (75.8%) and production of non-toxic products (39.8%) in closed batch reactors under an anaerobic condition. The effect of environmental factors (pH, contents of Ni and Pd in catalyst, and hydrogen gas concentration) on the reductive dechlorination of PCE by Pd-Ni/hematite catalysts was investigated. PCE was degraded less at the condition of Ni(5)/H (13.7%) than at the same condition with Ni(10)/H (20.6%). Removals of PCE were rarely influenced by the experimental condition of different Pd amounts (Pd(1)/H and Pd(3)/H). Acidic to neutral pH conditions were favorable to the degradation of PCE, compared to the alkaline condition (pH 10). Increasing Ni contents from 1 to 10% increased the PCE removal to 89.8% in 6 hr. However, the removal decreased to 74.2% at Ni content of 20%. Meanwhile, increasing Pd contents to 6% showed no difference in PCE removal at Pd content of more than 1%. Increasing H2 concentration increased the removal of PCE until 4% H2 which was maximumly applied in this study. Chlorinated products such as trichloroethylene, 1,1-dichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, and vinyl chloride were not observed while PCE was transformed to acetylene (24%), ethylene (5%), and ethane (11%) by Ni(10)-Pd(1)/H catalyst in 6hr.

• Journal of Aerospace System Engineering
• /
• v.2 no.2
• /
• pp.42-45
• /
• 2008

Under the non-operating exposure condition in the hot area, the T-50 cockpit temperature is expected over the requirement according to T-50 environmental criteria. So it is necessary to protect the cockpit from the high temperature condition during the non-operating exposure because the high temperature of the cockpit may result in the cockpit equipment malfunction. In this study, the transparency coating is selected as the method for protecting the cockpit from the high temperature exposure and analyzed the effect on the cockpit heat load attenuation. Some kinds of cockpit coating were reviewed and selected and the analysis was performed about the effect before and after coating application under 1% hot day condition based on the T-50 FSD hot soaking test data. The result of analysis show transparency coating is so effective to attenuate the heat load of T-50 cockpit.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.8 no.6
• /
• pp.45-58
• /
• 2005

The objective of this study is to the integrated evaluation of the present condition and satisfaction of visitors of rooftop greening area using quantitative and qualitative method. The thirteen green roofs were selected to investigate environmental variables as like building structure, soil, water, atmosphere and climate environment and questionnaire survey for investigate the satisfaction of visitors was conducted. The results of this study are as follows : remove of the hazardous inflow of species, install rain water recycling facility, install outdoor unit of air condition where not to affect plants in green roof, install safety facilities in the case of making resting place, plant variable vegetation and so on. The result of questionnaire survey are that visitors want to make more comfortable resting space. The more bigger the resting space and privacy, the more satisfaction of visitor became high. In conclusion, green roofs implementation should be considered reduction of temperature and delay of runoff, insulation effect and ecological restoration as well as rooftop greening is focused on the development of resting space nowadays.