• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.697-700
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• 2008

The underpotential deposited Bi on Pt($Bi_{upd}/Pt$) anode for formic acid fuel cells (FAFCs) was developed using multi-layered preparation method for better electrocatalytic utilization of Pt. The electron probe microanalysis (EPMA) result indicated that $Bi_{upd}$ remains through the catalyst layer during stability test. In performance test, the multilayered $Bi_{upd}$ on Pt black showed superior performance by approximately 200 mV at current density of $150mA/cm^2$ compared with PtRu black anode catalyst. Based on preparation condition of $Bi_{upd}/Pt$ black, carbon supported $Bi_{upd}/Pt/C$ electrode was prepared and it showed enhanced performance and stability.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.5
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• pp.837-844
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• 2017

Generally, V/C ratio in uninterrupted traffic flow and average travel speed in interrupted traffic flow are utilized as measure of effect for assessing operational situation of roads. The set of road conditions and traffic conditions are considered to be major variables for assessing operational situation in the traffic flow. However, weather conditions such as rainfall also affect the operational situation of roads. The studies reflected by the rainy situation are conducted in the uninterrupted flow, but the related studies are insufficient in the interrupted flow. In this study, the modification factors during rainfall in the interrupted flow were suggested, and the factors could be used when calculating the average travel speed during rainfall in the interrupted flow. By utilizing the data that were investigated in the same road and traffic conditions and the different weather conditions (rainy day or clear day), the modification factors were founded on regression analysis of the travel speed during rainfall as a dependent variable. Modification factors was suggested in dividing peak time, non-peak time, and whole period. Based on this study, the modification factors can be used to complementing the average travel speed model for assessing the operational situation of urban streets during rainfall.

• Journal of Environmental Science International
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• v.17 no.1
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• pp.107-112
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• 2008

A study on the enhancement of environmental durability of EPDM rubber materials for the aerator membrane was performed using a butyl rubber as a modifier. A conventional EPDM rubber formulation was evaluated as having about 26.0 wt% or more oil content from the chloroform immersion test. These oils would be gradually and continuously deleted from the aerator membrane when directly exposed to a waste-water or chemically corrosive fluids, making the membrane less flexible and the performance worse. To improve this, a butyl rubber (IIR) was utilized as the modifier for a low-ENB type of EPDM rubber formulation with low-oil content. The environmental durability of the IIR-modified EPDM rubber material was expected to be greatly enhanced compared to the conventional one. However, the mechanical and performance properties such as elongation, tensile strength, and air bubble size, etc. were still maintained as good as in the conventional one. Furthermore, TGA analysis of the IIR-modified EPDM material showed that there would be partially compatible between IIR and EPDM. It also showed that the initial degradation temperature of the IIR-modified EPDM could be somewhat increased, exhibiting the enhanced compatibility among the components and, thereby, more enhanced environmental durability.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.49-57
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• 2000

This study was carried out to find the optimal condition to treat refractory organic matter which can’t treat clearly with biological treatment and to find the optimal division dosage and division dose timing in the modification of Fenton oxidation which is used resolve the problem that hydrogen peroxide is too expensive. The results are following; 1. The highest TOC removal efficiency was 41% and color removal efficiency was 64% when the dilution magnitude of leachate is fold. This suggests that dilution is efficiency when high concentration of leachate is treated. 2. The removal efficiency of TOC and color increased up to the molar ratio between ferrate and hydrogen peroxide was 1:1. However above that ratio, removal efficiency hardly increased. The highest removal efficiency of TOC and color were 38% and 71% when the mole ratio of ferrate to hydrogen peroxide was 1.5:1. 3. When the mole ratio between ferrate and hydrogen peroxide was fixed, the removal efficiency of TOC and color increased as the dosage of hydrogen peroxide increased. 4. pH of samples were adjusted at pH 3, 5, 7, 9, 11. After oxidation reaction, pH of samples were dropped to 2.59, 2.54, 5.34, 6.36 and 9.68. The highest color removal efficiency was 75.7% when initial pH was at pH 7. 5. The removal of TOC and color was ended within 10. min. and the removal efficiency increased logarithmically within 10min. However after 10 min., the removal efficiency of hardly increased. 6. The color removal efficiency was higher with modification of fentone oxidation than that with fentone oxidation by 5%. Optimal division dosage ratio was 1:1 and optimal dose timing ratio was 2:1. However the TOC removal efficiency was not higher with modification of Fenton oxidation than that with Fenton oxidation.7. The CO $D_{Mn}$ /BO $D_{5}$ Ratio decreased with the time went by. It meant bioresolution increased as time went by. However, after 15 min., the CO $D_{Mn}$ /BO $D_{5}$ Ratio did not decrease any more. 8. In the case of $H_2O$$_2$ Divisiom Dose experiment, the increase of bioresolution was highest at the $H_2O$$_2$ Division dosage Ratio of 3:7.3:7.

• Journal of Environmental Health Sciences
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• v.39 no.1
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• pp.90-98
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• 2013

Objectives: Many studies have shown that air pollution and temperature have adverse effects on mortality and morbidity. But the interactive effect between air pollution and temperature on mortality has been rarely investigated. This study aims to explore whether temperature modifies the associations between ambient particulate matter less than $10{\mu}m$ in diameter ($PM_{10}$) and mortality in Seoul, Korea. Methods: The time-series analysis examined the effect of the interaction between $PM_{10}$ and temperature on mortality from 1999 to 2010 in Seoul. In order to examine the interactive effect between $PM_{10}$ and temperature on mortality, we fitted a response surface model controlling the time-trends and meteorological variables. The effects of $PM_{10}$ were stratified by temperature stratum to quantitatively estimate the $PM_{10}$-health outcome associations. Results: When temperature was low (below the threshold temperature), the percentage increases per $10{\mu}g/m^3$ increase of $PM_{10}$ increased 0.38% (95% Confidence Interval[CI]: 0.09~0.68%) and 0.31% (95% CI: - 0.07~0.68%) of mortality in the all age group and ${\geq}65$ year age group, respectively. When temperature was high (above the threshold temperature), the percentage increases per $10{\mu}g/m^3$ increase of $PM_{10}$ increased 1.09% (95% CI: 0.47~1.72%) and 1.35% (95% CI: 0.65~2.06%) for mortality in the all age group and ${\geq}65$ year age group, respectively. Conclusion: The results of this study showed strong modification by temperature in the association between $PM_{10}$ and mortality. We recommend that public health strategies to minimize adverse health impact of heat and $PM_{10}$ should be considered in control and prevention measures for air pollution and weather-related health impacts.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.346-349
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• 1996

In this paper development of a CAD of control systems is introduced which enables us to do not only analysis of control systems, design of controllers but also real-time implementation of controllers. By utilizing this software, the control engineer is able to repeat the procedure of modification of controllers and experiments without recompile to attain better performance. The software also offers the facility to update the parameters of controllers without stopping real-time control, which helps on-line tuning of controllers. If some parameters of the controller is changed on-line, the control input may change discontinuously. It has serious effect on the control systems. A method for on-line tuning of state feedback controller with state observer is proposed and verified through the experiment with an inverted pendulum.

• Journal of Environmental Science International
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• v.14 no.1
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• pp.15-22
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• 2005

Natural gas possesses several characteristics that make it desirable as an engine fuel; 1)lower production cost, 2)abundant commodity and 3)cleaner energy source than gasoline. Due to the physics characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of $10-20{\%}$ when compared to a normal gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of compression ratio, air/fuel ratio, spark advance and supercharging and method of measuring flame propagation velocity. It emphasizes how to improve the power characteristics of a natural gas engine. Combustion characteristics are also studied using an ion probe. The ion probe is applied to measure flame speed of gasoline and methane fuels to confirm the performance improvement of natural gas engine combustion characteristics.

• Journal of Environmental Science International
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• v.9 no.1
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• pp.65-74
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• 2000

In this study, we investigated the site feasibility for the construction of the incineration facilities in Won Ju City. To assess the environmental impact of its construction, we examined the current status of air quality in the selected candidate sites and predicted the extent of air quality change upon its operation through modification of stack type. If the stack height is assumed to be 70 m, the concentrations of $SO_2$ and dioxin in the surrounding area were predicted to increase by 0.05 ppb and 0.09 pg/$m^3$, respectively. The impact of its operation was assessed and compared among different sites. According to this analysis, more impact was expected from the residential area for the Dan-Gye site than from agricultural areas of the Kwan-Sul and Sa-Je site.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.81-85
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• 2010

In recent years, environmental concerns have been raised on the use of poorly biodegradable fluids in electrical apparatus in regions where spills from leaks and equipment failure could contaminate the surroundings. The vegetable insulation oils are highly biodegradable, have negligible effect on the environment, human health and ecosystem. Therefore, to assure their safe use in electrical power systems, it may require some processing and modification to improve some of their physical, chemical, thermal and electrical properties. This paper provides a comparative results of the electrical breakdown properties of several vegetable insulation oils and mineral oil to use as dielectric fluid in environmental-friendly pole transformer. Also, the electrical breakdown property of the Nomex and kraft insulation papers in vegetable insulation oil is examined.

• Advances in environmental research
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• v.1 no.1
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• pp.57-68
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• 2012

Recent studies showed that air pollution is a risk factor for hospitalization for chronic obstructive pulmonary disease (COPD). However, there is limited evidence to suggest which subpopulations are at higher risk from air pollution. This study was undertaken to examine the modifying effect of specific secondary diagnosis (including hypertension, diabetes, pneumonia, congestive heart failure) on the relationship between hospital admissions for COPD and ambient air pollutants concentrations. Hospital admissions for COPD and ambient air pollution data for Taipei were obtained for the period from 1999-2009. The relative risk of hospital admissions for COPD was estimated using a case-crossover approach. None of the secondary diagnosis we examined showed much evidence of effect modification.