• 한국수자원학회논문집
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• 제48권1호
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• pp.1-8
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• 2015

본 논문에서는 지난 20여 년간의 낙동강 하상변동 자료와 준설 및 골재채취 자료, 그리고 지류로부터 유입되는 유사량 관측 자료 및 수치모의 자료 등을 조사, 검토, 분석하여 4대강살리기 사업 전의 낙동강 하도에서의 개괄적인 유사수지 특성을 분석하였다. 4대강살리기 사업 전 낙동강 하도의 유사수지분석 결과, 유역에서 하도로 유입된 유사량은 $2,100,000m^3/yr$이며 낙동강으로부터 유출 또는 준설된 유사유출 총량은 $10,180,000m^3/yr$인 것으로 나타났다. 따라서 유사수지 분석을 통해 산정된 낙동강 하도에서의 하상변동량은 $-8,080,000m^3/yr$으로 하상이 침식된 것으로 나타났으며 이는 실제 하도측량 자료 분석을 통해 도출된 낙동강 본류의 자연적 그리고 인위적인 하상변동량($-8,300,000m^3/yr$)과 유사한 것으로 나타났다.

• 생태와환경
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• 제49권3호
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• pp.208-214
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• 2016

본 연구에서는 국내 수돗물 관련 연구 동향을 파악하기 위해 805건의 연구문헌 정보를 수집하여 텍스트 마이닝 기법으로 주제어 관계 분석을 시행하고 수돗물 이용에 대한 설문조사를 진행하여 사회적 인식을 조사하였다. 수돗물에 연관된 연구는 1990년대부터 수가 크게 증가한 것으로 파악되었으나 정확한 수돗물 불신의 원인파악과 대국민 소통에 대한 전문적인 연구는 매우 미흡하였다. 그동안 진행된 주요 연구분야는 크게 상수도 수질, 불소농도조정사업, 수돗물 잔류물 영향, 미생물 관리의 4개 주제군으로 구분할 수 있었다. 수돗물 음용에 대한 대국민 설문조사결과 응답자의 22.4%만이 수돗물을 주 음용수로 이용하고 있었으며 그대로 마시는 비율은 4.5%로 매우 낮게 나타났다. 수돗물의 주 음용수 사용에 미치는 주요한 영향요인으로는 수돗물 품질보고서 인지 여부, 수돗물 관리 정책에 대한 신뢰도 등의 영향력이 큰 것으로 나타났다. 지속적인 수돗물 음용 확대를 위해서는 수돗물 관리 정책 소통의 전환과 연구정보 공유 확산을 통해 이용자의 사회적 관심과 기관의 신뢰를 높여야 한다. 이를 위해 철저하게 관리되고 있는 수돗물 수질에 대한 객관적인 정보전달 체계를 확대하여 사회공공서비스의 모범을 제시해야 할 것으로 생각된다. 또한, 수돗물 불신에 대한 이용자 인식과 행동 원인에 대한 연구와 이를 해결하기 위한 실험적 접근들이 동시에 이루어져야 할 것으로 판단된다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.275-280
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• 2001

Typically, manganese (II) ions are incompletely removed from water as $MnO_2$ on increasing the pH of the water to 10. The water then has to be neutralized before it can be used. We propose a new and effective method for removing Mn (II) from water using a new combination of symbiotic microbes consisting of manganese-oxidizing bacteria and filamentous algae. The microbes rapidly oxidize Mn(II) to Mn (IV) at a neutral pH with no organic matter required as a nutrient and $MnO_2$is precipitated immediately. This differs from the use of heterotrophic manganese-oxidizing bacteria where organic nutrients are required. Our results suggest that this method will be useful in developing new systems for removal of manganese(II) ions from industrial and mining wastewater and drinking water. In addition, there are other possibilities such as recycling of dry batteries which are presently discarded without treatment

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.1965-1969
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• 2014

A new tetranuclear Mn(III) complex $[Mn^{III}{_4}(sae)_4({\mu}_3-O)({\mu}_{1,1}-N_3)(OH)(H_2O)_2]{\cdot}H_2O$ (1) ($H_2sae$ = 2-salicylideneamino-1-ethanol) has been synthesized by the reaction of $MnCl_2{\cdot}4H_2O$, $H_2sae$ and sodium azide in the mixed solvent of methanol, acetonitrile and water. The X-ray diffraction analysis shows that the four Mn(III) ions in complex 1 have a unique adamantine arrangement, whereas the coordination environment of each Mn(III) ions is different. Magnetic studies indicate that complex 1 manifests antiferromagnetic behaviors. The magnetic susceptibilities of complex 1 have been fitted by two magnetic models based on the suitable analysis of its magnetic structural topology.

• 한국해양공학회지
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• 제19권2호
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• pp.82-89
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• 2005

This study deals with the development of the extended Kalman filter(EKF) algorithm for the localization of underwater mining vehicles. Both simulation and experimental studies in a test bed are carried out. For the experiments, a scale dawn tracked vehicle is run in a soil bin containing cohesive soil of bentonite-water mixture. To develop the EKF algorithm, we use a kinematic model including the inner/outer track slips and the slip angle for the vehicle. The measurements include the inner and outer wheel speeds from encoders, the heading angle from a compass sensor and a fiber optic rate gyro, and x and y coordinate position values from a vision system. The vision sensor replaces the LBL(Long Base Line) sonar system used in the real underwater positioning situations. Artificial noise signals mimicking the real LBL noise signal are added to the vision sensor information. To know the mean slip values of the tracks in both straight and cornering maneuver, several trial running experiments are executed before applying the EKF algorithm. Experimental results show the effectiveness of the EKF algorithm in rejecting the sensor measurements noise. Also, the simulation and experimental results show close correlations.

• Geomechanics and Engineering
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• 제20권6호
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• pp.517-525
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• 2020

The long-term stability of rock engineering is significantly affected by the time-dependent deformation behavior of rock, which is an important mechanical property of rock for engineering design. Although the hard rocks show small creep deformation, it cannot be ignored under high-stress condition during deep excavation. The inner mechanism of creep is complicated, therefore, it is necessary to investigate the relationship between microscopic creep mechanism and the macro creep behavior of rock. Microscopic numerical modeling of sandstone creep was performed in the investigation. A numerical sandstone sample was generated and Parallel Bond contact and Burger's contact model were assigned to the contacts between particles in DEM simulation. Sensitivity analysis of the microscopic creep parameters was conducted to explore how microscopic parameters affect the macroscopic creep deformation. The results show that the microscopic creep parameters have linear correlations with the corresponding macroscopic creep parameters, whereas the friction coefficient shows power function with peak strength and Young's modulus, respectively. Moreover, the microscopic parameters were calibrated. The creep modeling curve is in good agreement with the verification test result. Finally, the creep curves under one-step loading and multi-step loading were compared. This investigation can act as a helpful reference for modeling rock creep behavior from a microscopic mechanism perspective.

• 한국수산과학회지
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• 제53권5호
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• pp.740-751
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• 2020

In the aquaculture industry, few studies are analyzing big data for intrinsic meaning. Fishcare Laboratory (www.fishcare.kr) diagnostic data from 2016-2018 was analyzed for scuticociliatosis (caused by Miamiensis avidus) outbreak patterns in cultured olive flounder Paralichthys olivaceus in Jeju, Korea. The scuticociliatosis monthly occurrence ratio is reported in the summary table after preparing and filtering the basic dataset model. Nonparametric test results suggest differences in the water temperature, body length, and weight between groups with and without scuticociliatosis. Data distribution visualization revealed that shorter body length and lighter weight increased the occurrence of scuticociliatosis. The association rule mining technique was applied to determine the primary clinical signs of mixed scuticociliatosis and bacterial infections. Venn diagrams were used to report clinical signs and suggest commonalities. These results may help diagnose and treat fish and provide a decision-making reference.

• Computers and Concrete
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• 제15권2호
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• pp.167-181
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• 2015

"Mortar or concrete pneumatically projected at high velocity onto a surface" is called Shotcrete. Models that predict shotcrete design parameters (e.g. compressive strength, slump etc) from any mixing proportions of admixtures could save considerable experimentation time consumed during trial and error based procedures. Artificial Neural Network (ANN) has been widely used for similar purposes; however, such models have been rarely applied on shotcrete design. In this study 19 samples of shotcrete test panels with varying quantities of water, steel fibers and silica fume were used to determine their slump, cost and compressive strength at different ages. A number of 3-layer Back propagation Neural Network (BPNN) models of different network architectures were used to train the network using 15 samples, while 4 samples were randomly chosen to validate the model. The predicted compressive strength from linear regression lacked accuracy with $R^2$ value of 0.36. Whereas, outputs from 3-5-3 ANN architecture gave higher correlations of $R^2$ = 0.99, 0.95 and 0.98 for compressive strength, cost and slump parameters of the training data and corresponding $R^2$ values of 0.99, 0.99 and 0.90 for the validation dataset. Sensitivity analysis of output variables using ANN can unfold the nonlinear cause and effect relationship for otherwise obscure ANN model.

• Ocean and Polar Research
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• 제41권2호
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• pp.107-120
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• 2019

The frequency analysis of scientific terms using bibliographic information is a simple concept, but as relevant data become more widespread, manual analysis of all data is practically impossible or only possible to a very limited extent. In addition, as the scale of oceanographic research has expanded to become much more comprehensive and widespread, the allocation of research resources on various topics has become an important issue. In this study, the frequency analysis of scientific terms was performed using text mining. The data used in the analysis is a general-purpose scholarship database, totaling 2,878 articles. Hypoxia, which is an important issue in the marine environment, was selected as a research field and the frequencies of related words were analyzed. The most frequently used words were 'Organic matter', 'Bottom water', and 'Dead zone' and specific areas showed high frequency. The results of this research can be used as a basis for the allocation of research resources to the frequency of use of related terms in specific fields when planning a large research project represented by single word.

• Steel and Composite Structures
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• 제38권1호
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• pp.79-86
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• 2021

Due to the complex geological conditions, a large number of high quality coal seams was buried in the western of China which cannot be mining in open-pit methods. The dynamic properties of that coal cannot be studied easily in real site for the complex working condition. The compound coal blocks made on the basis of the real situation were studied in the laboratory. The physical and mechanical properties of the compound coal blocks and the raw coal were contrasted by using the UCS tests. The results show that the compound coal blocks made by mixing coal powder, cement and water in proportion of 2.5:2:1 are the closest to that of standard raw coal. Then the propagation of strain waves and crushing effects on the coal were studied in the compound coal blocks by using the super dynamic strain test system and the numerical calculated method of ANSYS/LS-DYNA. The results show that the diameter of the crushing zone in the compound coal blocks was similar to that in the numerical results. The fractures distribution in laboratory tests also has a similar trend to the calculation results. The measured strain waves at the distance of 50 cm, 100 cm, and 150 cm from the center of the charge are mainly concerned at -1.0×104 με and have a similar trend as that in the numerical simulation.