• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.1
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• pp.53-58
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• 2005

Water shortages are gradually accelerating because higher standards of living are required and water resources are more heavily utilized. Therefore, effective water treatment is necessary in order to retain the required qualify and amount of water. General treatment includes coagulation, flocculation, filtering, and disinfection. coagulation, flocculation, and disinfection are major components of water treatment processes. In this paper, a new automatic decision algorithm is proposed for coagulation. The proposed method shows how to determine the coagulant type and amount using data mining techniques.

• Journal of Korea Water Resources Association
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• v.53 no.3
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• pp.215-223
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• 2020

The objective of this study is to develop a prediction model of specific degradation using data mining classification especially for the rivers in South Korea river. A number of critical predictors such as erosion and sediment transport were extracted for the prediction model considering watershed morphometric characteristics, rainfall, land cover, land use, and bed material. The suggested model includes the elevations at the mid relative area of the hypsometric curve of watershed morphomeric characteristics, the urbanization ratio, and the wetland and water ratio of land cover factors as the condition factors. The proposed model describes well the measured specific degradation of the rivers in South Korea. In addition, the development model was compared with the existing models, since the existing models based on different conditions and purposes show low predictability, they have a limit about the application of Korean River. Therefore, this study is focusing on improving the applicability of the existing model

• Journal of Environmental Science International
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• v.1 no.1
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• pp.77-88
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• 1992

Distribution patterns of the chemical species, contained or dissolved in the sediments and porewater, were studied from the submarine environments around Deok-Jeok Island, Yellow Sea. The sediments in the study area are predominantly composed of medium to coarse sands, and consequently of very low organic carbon (0.003%) -0.26%o dry weight sediments). As opposed to the strong enrichment of porewater with nutrients and heavy metals in the ordinarily muddy, organic-rich sediillents, the porewater enrichment is not intense in this sandy, organic-poor sediments: porewater phosphate is enriched to the maximum of only seven (average two) times over that in the bottom water. Concentrations of the heavy metals dissolved in porewater show a bit greater enrichment than the nutrient: Zn shows the lowest enrichment (7 times that of the bottom water) and Mn the highest (450 times that of the bottom water). However, these enrichments of the chemical species in porewater are the natural consequences of decomposition of the organic matter in sediments, and still fall short in the magnitude of those in the muddy, organic-rich sediments. Mining of the sands in the study area may pose a threat to the seawater quality as it causes a large scale porewater discharge to the bottom water. The additional supply of the nutrients by this discharge may develop an eutrophic state and, in consequence, an excessive nitrification of the water column. Since the residence times of the nutrients are much longer than those of the heavy metals, a long-term monitoring of the concentration changes in the porewater nutrients is very important to assess the potential deterioration of the seawater associated with the sand mining in the study area.

• Geomechanics and Engineering
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• v.21 no.4
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• pp.357-369
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• 2020

Different from the conventional planar fracture and simplified Newton model, for power-law slurries with a lower water-cement ratio commonly used in grouting engineering, flow model in geological rough fractures is built based on ten standard profiles from Barton (1977) in this study. The numerical algorithm is validated by experimental results. The flow mechanism, grout superiority, and water plugging of pseudo plastic slurry are revealed. The representations of hydraulic grouting properties for JRCs are obtained. The results show that effective plugging is based on the mechanical mechanisms of the fluctuant structural surface and higher viscosity at the middle of the fissure. The formulas of grouting parameters are always variable with the roughness and shear movement, which play a key role in grouting. The roughness can only be neglected after reaching a threshold. Grouting pressure increases with increasing roughness and has variable responses for different apertures within standard profiles. The whole process can be divided into three stationary zones and three transition zones, and there is a mutation region (10 < JRCs < 14) in smaller geological fractures. The fitting equations of different JRCs are obtained of power-law models satisfying the condition of -2 < coefficient < 0. The effects of small apertures and moderate to larger roughness (JRCs > 10.8) on the permeability of surfaces cannot be underestimated. The determination of grouting parameters depends on the slurry groutability in terms of its weakest link with discontinuous streamlines. For grouting water plugging, the water-cement ratio, grouting pressure and grouting additives should be determined by combining the flow conditions and the apparent widths of the main fracture and rough surface. This study provides a calculation method of grouting parameters for variable cement-based slurries. And the findings can help for better understanding of fluid flow and diffusion in geological fractures.

• Economic and Environmental Geology
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• v.28 no.2
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• pp.165-176
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• 1995

Dongrae is one of the most famous hot spring resort area in the Republic of Korea. The water temperature ranges $50^{\circ}C{\sim}66$. The chemical composition of the thermal water is quite different from normal groundwater. $Na^+$ and $Cl^-$ are the main components, measured more than 75%, $Ca^{+{+}}$ is contained about 22% and the other ions such as $SO_4$ or $HCO_3$ are the minor components. The heat source is uprising along the fracture zone of granite which is indicated as a subsurface high temperature belt. During the research period of 1991~1992, the groundwater table was lowered down to the depth of about 100 m according to continuous increase of daily use of thermal water. The groundwater table was fluctuated with an amplitude of day, weak or seasion. The groundwater table was the lowest at 18:00 h in a day and also lowest at the weekend for the week period. There was a relavent relationship between drawdown and the amount of thermal water use on a long term base. To protect such a rapid drawdown of groundwater table, Dongrae resort area is now asked to take strong municipal control for the daily use of thermal water.

• Journal of Ocean Engineering and Technology
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• v.26 no.6
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• pp.66-73
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• 2012

A pressure compensated chamber of a pilot mining robot isolates and protects an electrical-electronic system from the ambient highly pressured water. Since the inner pressure of the chamber is compensated with outer water pressure using hydraulic oil and pressure compensator, there exists a pressure difference, less than 1 bar, between outer and inner surface. The structural safety of the chamber is obtained relatively easier than the canister type which inner pressure is kept as the atmospheric pressure. However, due to the adoption of box shape for space efficiency and usage of the transparent engineering plastic viewport for checking inner circumstance, the viewport can be largely deformed. This large deformation can cause an additional tensile force, called the prying force, to the bolt-flange connection parts of the viewport. In this paper, we suggest the structural design equation considering the prying action for designing the structure of a box-shape pressure compensated chamber.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.296-300
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• 2012

최근 지구 온난화에 따른 이상 기후변화로 인해 게릴라성 집중호우와 같은 다양한 강우패턴이 발생되고 있다. 특히 집중호우의 빈도 및 규모가 커지고 있으며 피해 또한 증가하고 있다. 이에 대한 대안으로 하도의 정비, 댐 건설, 제방의 증고와 같은 구조적인 대책과 홍수예경보, 홍수보험, 통합홍수관리와 같은 비구조적인 대책에 대한 접근이 이루어지고 있다. 그러나 미래 기후변화에 대한 예측의 한계와 구조적 대책의 물리적 한계를 감안할 때 구조적 대책에 의한 방법만으로 변화하는 기후에 대응하여 홍수재해를 완벽하게 대처하기에는 부족한 것이 사실이다. 따라서 비구조적 대책에 의한 홍수피해저감이 절실히 필요하다. 따라서 본 연구에서는 국제수문개발계획 대표유역인 낙동강유역에 위치한 위천유역을 연구대상으로 선택하였고 이러한 중소규모의 유역에서 홍수예경보의 한계를 극복하고 신뢰성을 높이기 위하여 홍수유출시에 일어나는 유역내의 복잡한 물리적인 현상을 직접 고려하지 않고 입력자료와 출력자료의 관계로부터 학습과 추론을 통해 결론을 도출해내는 신경망, 퍼지, 유전자 알고리즘과 같은 Date Mining 기법을 사용하여 자동우량과 자동수위에 의한 하류 홍수예경보시스템을 구축하기 위해 수위를 예측하였다.

• Journal of the Korean Chemical Society
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• v.12 no.1
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• pp.1-3
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• 1968

New chelating ligands, thiocatechol and p-chlorothiocatechol, have been synthesized and the acid dissociation constants were determined by potentiometric method in 50% dioxane-water; $pK_1 \;and\; pK_2$ were 7.28, 10.97 for thiocatechol and 6.37, 10.22 for p-chlorothiocatechol, respectively. Color reactions with various metal ions were studied. It was found that the above ligands are specific for Bi(III), Mo(VI) and W(VI) as an analytical reagent.

• Geomechanics and Engineering
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• v.32 no.3
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• pp.245-254
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• 2023

Through qualitative analysis and quantitative analysis, the contradictory conclusions about the stability of the settled goaf with two-layer coal seams subject to building load were obtained. Therefore, it is necessary to combine the additional stress method and numerical simulation to further analyze the foundation stability. Through borehole analysis and empirical formula analogy, the height of water-conducting fracture zone in No.4 coal and No.9 coal were obtained, providing the calculation range of water-conducting fracture zone for numerical simulation. To ensure the accuracy of the elastic modulus of broken gangue, the stress-strain curve were obtained by broken gangue compression test in dried state of No.4 coal seam and in soaking state of No.9 coal seam. To ensure the rationality of the numerical simulation results, the actual measured subsidence data were retrieved by numerical simulation. FISH language was used to analyze the maximum building load on the surface and determine the influence depth of building load on the foundation. The critical building load was 0.16 MPa of No.4 settled goaf and was 1.6 MPa of No.9 settled goaf. The additional stress affected the water-conducting fracture zone obviously, resulted in the subsidence of water-conducting fracture zone was greater than that of bending subsidence zone. In this paper, the additional stress method was analyzed by numerical simulation method, which can provide a new analysis method for the treatment and utilization of the settled goaf.

• Membrane Journal
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• v.32 no.1
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• pp.13-22
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• 2022

Ever increasing global energy demand gives rise to uncontrollable environmental pollution. Demand on fossil fuel and consequent carbon emission leads to global warming and climate change. Nuclear energy is an alternative source to generate clean energy but mining of nuclear fuel is associated with harmful chemicals. Mining of valuable minerals from sea water by membrane separation process is a cost effective along with environmental friendly process. Separation and adsorption based mining of valuable minerals from sea water are another efficient process. Recovery of actinides from rare earth elements are very challenging and expensive process. Pressure driven membrane separation process is economically more viable along with environmental process. In this review membrane separation process are based on polyether sulfone, polyamide, polyimide, polyamidoxine and hybrid membranes. In case of adsorption process, mainly amidoxime kind of adsorbent are discussed.