• 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 the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.575-581
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• 2012

The electrochemical oxygen demand (ECOD) is an additional sum parameter, which has not yet found the attention it deserves. It is defined as the oxygen equivalent of the charge consumed during an electrochemical oxidation of the solution. Only one company has yet developed an instrument to determine the ECOD. This instrument uses $PbO_2$-electrodes for the oxidation and has been successfully implemented in an automatic on-line monitor. A general problem of the ECOD determination is the high overpotential of electrochemical oxidations of most organic compounds at conventional electrodes. Here we present a new approach for the ECOD determination, which is based on the use of a solid composite electrodes with highly efficient electro-catalysts for the oxidation of a broad spectrum of different organic compounds. Lead dioxide as an anode material has found commercial application in processes such as the manufacture of sodium per chlorate and chromium regeneration where adsorbed hydroxyl radicals from the electro-oxidation of water are believed to serve as the oxidizing agent. The ECOD sensors based on the Au/$PbO_2$ electrode were operated at an optimized applied potential, +1.6 V vs. Ag/AgCl/sat. KCl, in 0.01 M $Na_2SO_4$ solution, and reduced the effect of interference ($Cl^-$ and $Fe^{2-}$) and an expended lifetime (more than 6 months). The ECOD sensors were installed in on-line auto-analyzers, and used to analyze real samples.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.153-153
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• 2000

Si 산화는 반도체 공정상 필요한 과정으로 산업적으로나 학문적으로 중요하고 많이 연구되었다. 이중에서 Si(1110-7x7표면에서 초기 흡착된 산소는 준안정적 상태로 존재하며 표면온도, 산소의 노출량 그리고 진공도에 따라 그 수명이 제한된다. 이러한 준안정적 상태의 산소의 화학적 성질은 여러 표면분석장비가 동원되어 연구되었으나 아직까지 논쟁이 되고 있다. 이 경우 산소가 어떤 상태로 존재하는가는 표면화학종을 검출함으로서 해결될 수 있다. 저에너지 Cs+ 이온 반응성 산란은 이러한 요구를 충족시킬수 있는 가장 적합한 실험 방법중의 하나이다. 저에너지 Cs+ 이온 산란의 특징 중의 하나는 입사된 Cs+ 이온이 표면에 흡착된 화학종과 충돌후 탈착되면서 반응을 하여 송이 이온을 형성한다는 것이다. 이 송이 이온을 관측함으로서 표면에 존재하는 화학종을 알아 낼 수 있다. 이에 산소가 흡착된 Si(111)-7x7 표면에서의 산소의 준안정적 상태가 저에너지 Cs+ 이온 산란 실험을 통하여 연구되었다. 실험은 0.2-2L(1Langmuir = 10-6 Torr x 1 sec) 산소 노출량과 -15$0^{\circ}C$ - $25^{\circ}C$의 표면온도 그리고 5eV - 20eV의 Cs+ 이온 충돌에너지에서 CsSiO+ 이온이 유일한 생산물로서 검출되었다. CsSiO+ 이온은 입사된 Cs+ 이온과 표면에 존재하는 SiO 분자가 충돌 후 반응하여 탈착된 것으로 생각된다. 이것은 낮은 산소 노출량 즉, 초기 산화 단계에서 SiO가 표면에 존재한다는 것을 의미한다. 즉, 산소 분자는 산화단계의 초기에 해리되어 표면에 흡착되고 선구물질인 SiO를 형성함을 제시한다. 최근의 이론적 계산인 density functional calculation에서도 산소분자가 Si(111)-7$\times$7 표면의 준안정적 산화상태의 선구물질일 가능성을 배제한다. 이는 본 저에너지 Cs+ 이온 반응성 산란실험을 뒷받침하는 계산 결과이다. 높은 Cs+ 이온 충돌에너지에서 CsSi+, Si+, SiO+, Si2+, Si2O+ 등이 추가로 검출되었다. 이는 CsSi 이온을 제외하고 수 keV의 충돌에너지를 사용하는 이차 이온 질량 분석법과 비슷한 결과이다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.3
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• pp.117-123
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• 2006

The water quality before and after a typhoon was investigated as a part of a study on the increase of organic matter and on the fundamental measures to counter chemical oxygen demand (COD) in the eutrophic Soho coastal seawaters of Gamak Bay. The dissolved oxygen (DO) saturations were <54% when water column was stratified. The DO saturation was similar at surface and in the bottom layer after a typhoon $(78\sim88%)$, and a very high DO saturation (234%) was observed in the surface water after mass phytoplankton growth. The highest values of $NH_4-N,\;NO_3-N,\;PO_4-P$, and $SiO_2-Si$ were 18.22, 38.90, 1.58, and $52.10{\mu}M$, respectively, when freshwater entered after heavy rainfall events. In addition, high concentrations of $NH_4-N,\;PO_4-P$, and $SiO_2-Si$ were detected with low DO saturations in bottom water (>5m). A maximum chlorophyll (Chl.) concentration of $311.0{\mu}gl^{-1}$ was observed after typhoon, when a high-density Scrippsiella trochoidea red tide occurred with cell density of 42,000 cells $ml^{-1}$. The algal growth potential (AGP) was high after the typhoon. Nitrogen was always a limiting nutrient for phytoplankton growth. The highest COD level was $10.55mgl^{-1}$, and the main reason of the variation in COD was likely to be phytoplankton growth $(r^2=0.612,\;p=0.000)$. Organic matter, which entered the water column when the typhoon stirred the sediments, seems to have little effects on COD increase.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.2
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• pp.140-145
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• 2002

The performances of a parallel current air driven type foam separator were evaluated in the pilot-scale recirculating aquaculture system. The system was stocked with Nile tilapia (Oreochromis niloticus) at an initial rearing densities of $2\%$, $5\%$ and $7\%$ of water volume of rearing tank and reared for 15, 30, 35 days, respectively. The condensated volume of effluent foam was increasing with increased rearing density. As increasing rearing density from $2\%$ to $7\%$, the protein concentration in rearing tank was increased from 16.6 g/$m^3$ to 21,9 g/$m^3$ and the removal amount of protein through foam separator as increased from 0.99 g/day to 2.5 g/day. But protein concentration ratio in the foam was decreased from 3.2 to 1.9. Changes of the removal amount and the concentration ratios of total suspended solid (TSS) and chemical oxygen demand (COD_cr.) were similar to proteins. The highest concentration ratios of TSS and COD_cr. were 10.2 and 8.4 at 2$2\%$ of rearing density.

• Analytical Science and Technology
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• v.11 no.3
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• pp.229-230
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• 1998

• Membrane Journal
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• v.9 no.3
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• pp.178-184
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• 1999

A periodic backflushing was performed to reduce the membrane fouling of ultrafiltration for wastewater, and the effect and the optimum condition were investigated in this study. The alumina¬ceramic tubular membrane with pore size of 0.02${\mu}m$ was used for the wastewater treated by coagulation and sedimentation from two paper plants, of which A plant made toilet paper by recycling milk paper cartons and B plant recycled corrugated cardboards. And the effect of periodic backflushing to membrane fouling and quality of permeate were studied with a constant backflushing time of 3 sec. As results of measuring SS, TDS, and COD of source and permeate, the rejection rate of SS showed the highest value at the backflushing period of 15 see, which was the shortest time in these experiments, in case of waste¬water discharged from A plant. However, the rejection rate of COD had the highest value at the period of 30 sec for wastewater from both A and B plant. Then, the rejection rate of TDS was almost same at 30 and 60 sec for A plant wastewater, and the highest at 60 see for B plant. The effect of periodic back¬flushing to membrane fouling was investigated by change of permeate flux according to operating time. The permeate flux decreased slowly at the operation with backflushing, and was higher compared with that without backflushing in both case of A and B wastewater. But, the optimum period with the highest flux of A wastewater was different from that of B, because SS and COD of A was higher than those of Band TDS of B was higher than that of A.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.373-384
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• 2011

The objective of this was to determine how the seasonal intensive rainfall influenced the water quality, and to analyze the long-term temporal trend of water chemistry and spatial heterogeneity in the upstream watershed of Southern Han River using water quality dataset from 1997 to 2007. The largest seasonal variability in most parameters occurred during the two month July and August and there were closely associated with a large spate of summer monsoon rain. Total phosphorus (TP), chemical oxygen demand (COD), and suspended solids (SS) were greater during summer than any other seasons, and had a direct correlation with precipitation (r>0.4, p<0.01, n-120). In addition, dissolved oxygen (DO) had and inverse function with precipitation (r=-0.542, p<0.01). Overall, the data of total phosphorus (TP) and suspended solids (SS) showed that water quality was worst in Site I1, compared to the others. This was due to continuous effluents from the highlands' fields and cattle farms within the upstream area of Doam lake (Song stream). Based on the overall dataset, an efficient water quality management is required in the highlands and farms areas for better water quality with precipitation (r.0.4, p<0.01, n=120).

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.2
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• pp.91-98
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• 2009

The long-term water-quality change of Asan Bay by the influx of polluted disposal water was predicted through a simulation with an Eco-hydrodynamic model. Eco-hydrodynamic model is composed of a multi-level hydrodynamic model to simulate the water flow and an ecosystem model to simulate water quality. The water quality simulation revealed that the COD(Chemical Oxygen Demand), dissolved inorganic nitrogen(DIN) and dissolved inorganic phosphorus(DIP) are increased at 5 stations for the subsequent 6 months after the influx of the effluent. COD, DIN and DIP showed gradual decreases in concentration during the period of one to two years after the increase of last 6 months and reached steady state for next three to ten years. Concentration levels of COD, DIN, and DIP showed the increase by the ranges of $11{\sim}67%$, $10{\sim}67%$, and $0.5{\sim}7%$, respectively, which represents that the COD and DIN are the most prevalent pollutants among substances in the effluent through the sewage treatment plant. The current water quality of Asan Bay based on the observed COD, TN and TP concentrations ranks into the class II of the Korean standards for marine water quality but the water quality would deteriorate into class III in case that the disposal water by the sewage plant is discharged into the Bay.