• KSBB Journal
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• v.21 no.4
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• pp.241-247
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• 2006

The present study was intended to examine a basic scheme to determine the biochemical oxygen demand(BOD) of livestock wastewater by means of six individual dissolved oxygen(DO) sensors and its multi-measurable meter. Maximal point of the first order time derivative of the DO difference between DO distribution of sterilized livestock wastewater and that of non-sterilized livestock wastewater, was considered as the oxygen uptake rate(OUR) of microorganisms in livestock wastewater, as determined to be 0.00074 mg $O_2/{\ell}{\cdot}sec$. The present study showed that there was a fair linear relationship(97.72%) between maximal OUR and BOD values of livestock wastewater, the latter being determined by classical Winkler azide method. It was thus concluded that the present multi-biosensor system might be applicable to an on-line system for measurement of BOD of livestock wastewater.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.81-96
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• 2011

Sediment oxygen demand(SOD) and denitrification rates were measured in four major estuaries(Suncheon Bay, Seomjin river estuary, Goseong stream estuary and Masan Bay) in south coast of Korean peninsula from March of 2009 to May 2010 to estimate organic matter cleaning capacity. SOD was estimated from the temporal dissolved oxygen concentration change and isotopic pairing technique was employed to measure denitrification. Sediment oxygen demand(SOD) was ranged from -5.1 to 24.6 mmole $O_2m^{-2}d^{-1}$ and denitrification rate was ranged from 0.0 to 3.9 mmole $N_2m^{-2}d^{-1}$in the study area. SOD was the highest in Masan Bay(-2.2 to 19.2, average = 10.2 mmole $O_2m^{-2}d^{-1}$) and Suncheon, Goseong, Tae-an and Seomjin followed. Denitrification was also the highest in Masn Bay(0.0 to 3.9, average = 1.0 mmole $N_2m^{-2}d^{-1}$) and Goseong, Seomjin, Suncheon and Taean followed. The effect of benthic photosynthesis by microphytobenthos on denitrification was evident in some season of Tae-an, Seomjin, and Masn Bay. The increased oxygen level produced by photosynthesis stimulated nitrification without severe adverse effect on denitrification and, as a result, coupled nitrification and denitrification was enhanced in these areas. A difference of seasonal patterns of denitrification at each site depended on relative importance of denitrification on different nitrate source($D_w$: nitrate from water column and $D_n$: nitrated produced during nitrification). Denitrification was maximum during spring in Goseong, Suncheon and Masan Bay. On the contrary, denitrification was the highest during summer in Tae-an and Seomjin estuary.

• Proceedings of the Membrane Society of Korea Conference
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• 1992.10a
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• pp.13-14
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• 1992

고분자막을 이용한 분리공정에서 본질적으로 요구되는 성능은 우수한 선택도와 투과속도인데, 이러한 특성들은 막의 화학구조 및 막의 두께 등에 의하여 영향을 받는다. 따라서 선택투과기체와 친화성이 좋은 물질을 박막화하여 제조한다면 분리막으로 우수한 성능을 지닐 수 있을 것이다.

• Fire Science and Engineering
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• v.30 no.2
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• pp.87-91
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• 2016

Recently, it has been increasing an incidence of heart diseases which is a causative factor in sudden death as Korean population structure has been changing to an aging society. There is growing needs for A portable ventilator which automatically be operated by the pressure of the supplied oxygen and has been spread worldwide. So, we would like to present test methods in accordance with the performance requirements which are important for components of a respirator and a portable ventilator itself. And also would like to find the most suitable condition of internal pressure reduction for the performance requirements according to the changing conditions of internal pressure reduction setting of a portable ventilator.

• Journal of the Korean Data and Information Science Society
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• v.21 no.5
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• pp.883-890
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• 2010

Illegal waste dumping is one of the major problems that the government agency monitoring water quality has to face. One solution to this problem is to find an efficient way of managing and supervising the water quality under various kinds of conditions. In this article we establish WQMA (water quality monitoring algorithm) based on the time series intervention model. It turns out thatWQMA is quite successful in detecting illegal waste dumping.

• Analytical Science and Technology
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• v.8 no.2
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• pp.167-170
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• 1995

A simple and rapid permanganate value test procedure for the estimation of COD, based on the photometric measurement of the remained permanganate after the color bleaching by oxygen demand organics during digestion, has been described. Optimized conditions were 1% NaOH, 0.6mM $KMnO_4$, with a closed reflux in the boiling water bath for 90 sec using sample size of 5mL.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.488-498
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• 2016

In order to assess the role of aeration in stormwater wetlands, oxygen supply and consumption in a wetland treating runoff from livestock farms were estimated and analyzed. Furthermore, oxygen mass balance was conducted during day time and night time. Internal production by algal photosynthesis dominated the oxygen production particularly in the shallow marsh due to the large amount of algae. Consequently, algal respiration was also the major oxygen depletion element with nitrification and biodegradation estimated as 5.35% and 6.43% of the total oxygen consumption. This excessive portion of oxygen consumption by algae was associated to the highly turbid water caused by the resuspension of sediment particles in the aeration pond, which also affected the subsequent wetland. Moreover, an abundance of oxygen was estimated during the day indicating that oxygen produced by algal activity is sufficient to meet the oxygen demand in the wetland. Thus, supplemental aeration was deemed not necessary at daytime. In contrast, oxygen was greatly depleted at night when algal photosynthesis stopped which induced denitrification. Therefore, it was suggested that supplemental aeration may be operated continuously instead of intermittently to avoid oxygen deficit in the wetland at night or it may be stopped entirely to further enhance denitrification.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.842-846
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• 2016

It's possible for a human to breathe under water, but the amount of dissolved oxygen in the water is small and a large amount of water is necessary to obtain sufficient dissolved oxygen from water. So, large separation system with large water pumps, having large surface areas, and large battery sources are needed. Exhalation gases are used to solve this problem. Theses gases contain some oxygen, nitrogen, and carbon dioxide; they contain less oxygen and more carbon dioxide compared to air. Therefore, reduction of the amount of carbon dioxide is necessary. If exhalation gases are employed appropriately, the separation device can be made more compact. Inlet water mixed with exhalation gases is supplied into the separation device, and dissolved gases are separated from the mixed water as it passes through the device. The inlet part of a typical separation system with a water delivery pump before the membrane module has more than one atmosphere. Hence, a compressor is used to mix the exhalation gases. In this study, the pressure at the inlet due to the use of a suction pump after the membrane module was less than one atmosphere; hence, compressors were not required. Separation characteristics were studied using a separation device without a compressor. The use of exhalation gases led to an increase in the amount of dissolved gases being separated. As the amount of inlet exhalation gases was increased, the separation of dissolved gases was increased as well.

• Journal of Life Science
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• v.22 no.10
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• pp.1286-1294
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• 2012

Biological assessments of the macrobenthos community were carried out in the Seomjin River from May 2009 to November 2010. Fishes from 106 species belonging to 24 families and 10 orders were collected from the survey sites. Locational dominant species differed among sites, and the numbers of species and individuals differed depending on site, although six sites were not significantly different on the same survey dates. Across sites, the average number of species was 38.3, ranging from five at site 1 to 66 at site 2 in May 2009. Site 2 had the highest number of species on November 2009, while site 3 had the lowest. Arthropods dominated the macrobenthic community at species (63.2% May) and individual (60.9% November) levels. DO, BOD, and COD were shown to have the greatest effect on the numbers of macrobenthos. Peaks in the diversity index trended downwards from upstream to downstream sites.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.108-116
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• 2018

A firing test of the 75 tonf-class liquid rocket engine to be used as the first and second stage engines of the KSLV-II was carried out at the rocket engine test facility(RETF). Since this engine uses liquid oxygen as the oxidizer, which is a cryogenic fluid, it is essential that the chill down of the supply pipe line and engine proceed for the firing test; thus, the given inlet requirements must be met. Moreover, it is important to understand the chill down characteristics of the facility and the engine and the amount of liquid oxygen consumed in the chill down process for efficient test operation in the future. In this paper, chill down characteristics of the supply pipe and the engine were evaluated through the investigation of the chill down process of the 75 tonf-class liquid rocket engine at each stage before and after run tank pressurization. In addition, the amount of liquid oxygen consumed was also evaluated.