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Relationship between groundwater and climate change in South Korea
이병대,함세영,장성,정재열,김규범 한국지질과학협의회 2014 Geosciences Journal Vol.18 No.2
Climate change has resulted in a gradual increase inthe surface temperature and significantly variable precipitation indifferent regions of the world. Linear regression of the groundwaterlevels in Korea between 2000 and 2010 revealed a decreasingtrend with a slope of –29.2 mm/yr; –29.6 mm/yr in the wet seasonand –32.0 mm/yr in the dry season. Mann-Kendall and Sen’s testswere carried out using the groundwater levels and groundwatertemperatures at 78 locations in South Korea between 2000 and2010. The groundwater levels showed a trend in ~50% of the 78groundwater level datasets, of which ~70% exhibited a decreasingtrend at the 95% confidence level. This decreasing trend in thegroundwater levels appears to be related to a change in the precipitationin South Korea because more abundant rainfall in thewet season each year does not contribute significantly to groundwaterrecharge, whereas less rainfall that occurs in the dry season cancause a decrease in the groundwater level. Linear regression of thegroundwater temperatures revealed a slope of 0.1006 °C/yr between2000 and 2010 with a gentler slope (0.08 °C/yr) in summer (June–September), showing that the increase in surface temperature hasan impact on increasing the groundwater temperature. In this situationof climate change in Korea, the paradigm of groundwatermanagement strategy needs to be altered properly.
단계 주입 활성슬러지공법에서 질소제거를 위한 반응기 용적비 추정
이병대 한국응용과학기술학회 2006 한국응용과학기술학회지 Vol.23 No.2
Theoretical total nitrogen removal efficiency and reactor volume ratio in oxic-anoxic-oxic system can be found by influent water quality in this study. The influent water quality items for calculation were ammonia, nitrite, nitrate, alkalinity, and COD which can affect nitrification and denitrification reaction. Total nitrogen removal efficiency depends on influent allocation ratio. The total nitrogen removal follows the equation of 1/(1+b). Optimal reactor volume ratio for maximum TN removal efficiency was expressed by those influent water quality and nitrification/denitrification rate constants. It was possible to expect optimal reactor volume ratio by the calculation with the standard deviation of ±14.2.
원주지역 지하수의 자연방사성물질 우라늄과 라돈의 산출 특성과 수리지화학
이병대,조병욱,문희선,황재홍 대한지질공학회 2019 지질공학 Vol.29 No.4
We measured the concentrations of natural radionuclides (uranium and radon) and major elements in groundwater collected from forty wells located in Wonju area to investigate the hydrochemistry and the occurrence of these radionuclides. The range of electrical conductivity (EC) value in the study area was 73~400 μS/cm. In addition to the increase of EC value, the content of cations and anions also tends to increase. Uranium concentrations ranged from 0.06~50.5 μg/L (median value, 1.55 μg/L) and radon concentrations ranged from 67~8,410 pCi/L (median value, 1,915 pCi/L). Uranium concentrations in 3 well, 7.5% of the samples, exceeded 30 μg/L, the maximum contaminant level (MCL) proposed by the US Environmental Protection Agency (EPA), based on the chemical toxicity of uranium. Radon concentrations in 9 wells, 22.5% of the samples, and 1 well, 2.2% of the samples, exceeded 4,000 pCi/L (AMCL of the US EPA) and 8,100 pCi/L (Finland’s guideline level), respectively. Concentrations of uranium and radon related to geology of the study area showd the highest values in groundwater of the biotite granite area. Uranium and radon contents in the groundwater are comparatively low compared to those in other countries with similar geological settings. It is likely that the measured value was lower than the actual content due to the inflow of shallow groundwater by the lack of casing and grouting. 원주지역 지하수의 수리지화학 및 자연방사성물질인 우라늄과 라돈의 산출특성을 규명하기 위하여 40개관정을 대상으로 시료를 채취하고 분석하였다. 연구지역 지하수의 EC는 최소 73에서 최대 400 μS/cm (평균 212 μS/cm)의 범위를 나타내고 있으며, EC의 증가와 더불어 주요 용존 양이온과 음이온의 함량도증가하는 경향을 나타낸다. 우라늄 농도는 0.06~50.5 μg/L (중앙값 1.55 μg/L)로 넓은 분포를 보여주고 있으며, 라돈은 67~8,410 pCi/L (중앙값 1,915 pCi/L)의 범위를 나타내고 있다. 우라늄 농도에서 미국 EPA MCL 30 μg/L를 초과한 곳은 3개소로 전체 시료수의 7.5%에 해당된다. 라돈의 경우, 미국 EPA AMCL(Alternative Mximum Contaminant Level) 4,000 pCi/L를 초과한 곳은9개소로 전체 시료수의 22.5%이다. 이중 핀란드의 음용 제안치인 8,100 pCi/L를 초과하는 시료는 1개소이다. 연구지역에서 지질별 지하수의우라늄과 라돈 농도는 흑운모화강암 지역의 지하수에서 가장 높다. 연구지역 지하수의 우라늄과 라돈 함량은 유사한 지질을 가지는 외국에 비하면 낮은 것으로 나타났다. 이는 우리나라 지하수 관정의 특성상 케이싱 및 그라우팅이 미비한 관정이 많으므로 천부 지하수의 공내 유입을의심할 수 있다. 이러한 관정의 특성으로 인하여 실제 함량보다 낮게 검출되었을 가능성을 배제할 수 없다.
Theoretical Analysis for Nitrogen Removal in Step Feed Oxic-Anoxic-Oxic Process
이병대,김일출 한국응용과학기술학회 2008 한국응용과학기술학회지 Vol.25 No.3
One of the popular domestic sewage treatment process (called step feed oxic-anoxic-oxic process) for nitrogen removal was analyzed in this study by theoretical analysis based on the nitrification and denitrification reaction. Total nitrogen removal efficiency was suggested by considering influent qualities(i.e., ammonia, nitrite, nitrate, alkalinity, and COD). Total nitrogen removal efficiency depends on r (influent allocation ratio). In the case that all influent components are enough, the total nitrogen removal follows equation 100b/(1+b), when r is 1/(1+b). Finally, it can be concluded that step feed oxic-anoxic-oxic process could be effective for nitrogen removal.
이병대 한국응용과학기술학회 2011 한국응용과학기술학회지 Vol.28 No.1
Step feed process was analyzed stoichiometrically for the optimal operation conditions in this study. In case of optimal operation conditions, minimum R (sludge recycling) value, r (internal recycling ratio) value, and n (influent allocation ratio) value for the step feed process to acquire the maximum TN removal efficiency were identified by theoretical analysis. Maximum TN removal efficiency, based on stoichiometric reaction, can be obtained by controlling n value for the step feed process.
이병대 한국응용과학기술학회 2016 한국응용과학기술학회지 Vol.33 No.3
The intermediate product resulting from the radical degradation experiment of PCEand the atomic charge gained through Gaussian03W were compared against each other. The resultwas that the ratio of PCE radical degradation was almost 98% or higher after the 9 hr point inreaction time. The reaction speed constant was 0.16 hr-1 and it followed the first reaction. Wecould see that at each location of the PCE molecule, dechlorination happened at a point where thenegative atomic charge was the greatest. Moreover, the intermediate product of PCE radicaldegradation that was confirmed in the experiment and literature coincided exactly with theintermediate product in the atomic charge calculation. Therefore, when the atomic charge iscalculated, the radical degradation pathway of the organic chlorine compound could be forecast.