• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.34-41
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• 2012

The variation of dissolved oxygen (DO) was monitored with high frequency by an automatic data-logging sensor in a eutrophic urban stream (the Anyang Stream) located in a metropolitan area of Seoul, South Korea. In general, DO showed the diel variation of increase in daytime and decrease at night, implying that primary production is a major mechanism of oxygen supply in this ecosystem. The fluctuation of oxygen was determined by rainfall. DO depletion was most obvious after a rainfall resulting in an anoxic condition for a day, which is thought to be caused by scouring of periphyton and organic ooze at the stream bottom. Seasonally DO was higher in winter and frequently depleted in warm seasons. DO depletion was often at a dangerous level for fish survival. Fish survey showed that little fish was living at the study site and oxygen depletion may be the major stress factor for aquatic animals. From the results it can be suggested that a high frequency monitoring of oxygen should be established for the proper assessment of aquatic habitats and better management strategy.

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.119-125
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• 1996

The experimental work is performed to obtain content levels and characteristics of flue gas in infrared mobile heaters for butane gas with varying the chamber size and its room temperature. The results showed that the oxygen depletion sensor device is operated at 18.3% of oxygen content. And the relation of oxygen content and carbon dioxide content in an enclosed space show linear aspect, but the content rate of carbon monoxide occurs at random without the level of oxygen content and carbon dioxide content.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.66-73
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• 1998

This paper deals with the combustion characteristics of flue gas in infared mobile heaters. The experimental work has been performed to obtain the concentration levels and combustion characteristics of flue gas with varying chamber size and room temperature. The experimental results showed that oxygen depletion sensor device was operated at the oxygen concentration level of $18.3\%$ for all the chamber size. The combustion characteristics of oxygen and carbon dioxide show a linearity After 10 minutes the combustion property of carbon monoxide occurs at random without a level of oxygen and carbon dioxide in closed space of the heater. In these results, it is very important to prevent incomplete combustion through a sufficient ventilation, and accident prevention with a reduction of the oxygen and diffusion of toxic carbon monoxide.

• Corrosion Science and Technology
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• v.3 no.6
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• pp.227-232
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• 2004

The carboxylates as a corrosion inhibitor has been studied by many researchers because of its environmental safety and low depletion rate. However, conventional test methods of inhibitor such as weight loss measurements, linear polarization resistance and corrosion potential monitoring etc., evaluate uniform corrosion of metals. These methods are unable to evaluate crevice-related corrosions, which are encountered in most of heat exchanging facilities. In order to choose the optimum corrosion inhibitor, the appropriate test methods are required to evaluate their performances in service environment. From this point of view, polarization technique was used to evaluate the characteristics of sodium heptanoate on corrosion behavior for carbon steel. Especially a thin film crevice sensor technique were applied to simulate the crevice corrosion in this study. From these experiments, we found that oxygen as an oxidizing agent was required to obtain stable passive film on the metal. Presence of oxygen, however, accelerated crevice corrosion. Potential shift by oxygen depletion and weakened inhibitive film inside the crevice were responsible for such accelerated feature. It is shown that film for corrosion inhibition is a mixture of sodium heptanoate and iron (II) heptanoate as reaction product of iron surface and sodium heptanoate. The iron (II) heptanoate which has been synthesized by reaction of heptanoic acid and ferrous chloride in methanol solution forms bidentate complex.