• Computers and Concrete
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• 제21권6호
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• pp.623-635
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• 2018

In order to research the influence of different recycled aggregate contents on the mechanical properties of pervious concrete, the experimental study and numerical simulation analysis of the mechanical properties of pervious concrete with five kinds of recycled aggregates contents (0%, 25%, 50%, 75% and 100%) are carried out in this paper. The experimental test were first performed on concrete specimens of different sizes in order to determine the influence of recycled aggregate on the compressive strength and splitting tensile strength, direct tension strength and bending strength. Then, the development of the internal cracks of pervious concrete under different working conditions is studied more intuitively by $PFC^{3D}$. The experimental results show that the concrete compressive strength, tensile strength and bending strength decrease with the increase of the recycled aggregate contents. This trend of reduction is not only related to the brittleness of recycled aggregate concrete, but also to the weak viscosity of recycled aggregate and cement paste. It is found that the fracture surface of pervious concrete with recycled aggregate is smoother than that of natural aggregate pervious concrete by $PFC^{3D}$, which means that the bridging effect is weakened in the stress transfer between the left and right sides of the crack. Through the analysis of the development of the internal cracks, the recycled aggregate concrete generated more cracks than the natural aggregate concrete, which means that the recycled aggregate concrete is easier to form a coalescence fracture surface and eventually break.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.176-176
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• 2019

Thailand had issued a national strategic development master plan with issues related to water resources and water security in the entire water management. Water resources are an important factor of living and development of the country's socio-economy to be stable, prosperous and sustainable. Therefore, water management in both multidimensional and multi-sectoral systems is important and will supports socio-economic and environmental development. The direction of national development in accordance with the national strategic framework for 20 years that requires the country to level up security level in terms of water, energy and food. To response to the proposed goals, there is a subplan to increase water productivity of the entire water system for economical development use by evaluating use value and to create more value added from water use to meet international standard level. This study aims to evaluate the water productivity of Thailand in each basin and all sectors such as agricultural sector, service and industrial sectors by using the water use data from water account analysis and GDP data from NESDB during the past 10 years (1996-2015). The comparison of water productivity with other countries will also be conducted and in addition, the measures to improve water productivity in next 20 years will be explored to response to the National Strategic Master Plan goals. Water productivity is defined as output per unit of water depleted. The simplest way to compare water productivity across different enterprises is in monetary terms. World Bank presents water productivity as an indication of the efficiency by which each country uses its water resources. There are two data sets used for water productivity analyses, i.e., the first is water use data at end users and the second is Gross Domestic Product. The water use at end users are estimated by water account method based on the System of Environmental-Economic Accounting for Water (SEEA-Water) concept of United Nations. The water account shows the analyses of the water balance between the use and supply of each water resource in physical terms. The water supply and use linkage in the water account analyses separated into each phases, i.e., water sources, water managers, water service providers, water user at end user under water regulators of all kinds of water use activities such as household, industrial, agricultural, tourism, hydropower, and ecological conservation uses. The Gross Domestic Product (GDP), a well- known measuring method of the national economic growth is not actually a comprehensive approach to describe all aspects of national economic status, since GDP does not take into account the costs of the negative impacts to natural resources that result from the overexploitation of development projects, however, at present, integrating the environment with the economy of a country to measure its economic growth with GDP is acceptable worldwide. The study results will show the water use at each basin, use types at end users, water productivity in each sector from 1996-2015 compared with other countries, Besides the productivity improvement measures will be explored and proposed for the National Strategic Master Plan.

• 한국콘텐츠학회논문지
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• 제17권4호
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• pp.1-11
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• 2017

신재생에너지에 대한 관심이 증가하고 있지만 부정적인 여론으로 인해 초소수력 발전소 개발이 부진한 실정이다. 그러나 다른 신재생에너지에 비해 에너지 변환효율이 높고 이산화탄소를 배출하지 않아 대체에너지로써 개발 및 확대에 대한 관심이 필요하다. 이에 본 연구는 이클립스(Eclipse)를 이용하여 초소수력 발전량을 가시화하는 지도를 담는 애플리케이션을 개발하였다. 이를 통해 먼저 대상지점을 선택하고 미 공병단에서 제공하는 HEC-HMS으로 산출한 확률 설계유량으로 발전용량을 산정한 후 경제성 분석을 수행할 수 있다. 시범지역으로 강수량이 풍부한 강원도 영월군을 선정한 후, 국가수자원관리종합정보에서 제공하는 기초자료를 이용하여 초소수력 발전 잠재량 분석을 수행하였다. 본 연구 결과로 대상지점의 예상발전량, 연간전기생산량, 경제성분석 등을 단시간에 평가할 수 있고, 전국을 대상으로 잠재되어 있는 초소수력 발전 가능지역을 선별하는데 활용될 것으로 기대된다. 또한 간편하게 발전 가능지역을 선별할 수 있기 때문에 초기 투자비용을 줄일 수 있을 것으로 판단된다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.106-106
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• 2011

소수력은 온실가스 배출량이 적은 친환경 청정에너지원이면서 지역의 분산전원에 기여할 수 있는 유용한 자원으로 평가되고 있다. 이러한 여건은 소수력발전 사업이 전력의 smart grid 구축 효과로 인해 가장 큰 효율성을 달성할 수 있을 것으로 기대된다. 국내 소수력발전은 1500Mw의 부존량을 가진 것으로 평가되고 있으나 계절적 편중으로 인한 가동률 부족, 경제성 부족 등으로 활발한 보급이 이루어지지 않고 있다. 특히 신재생에너지 확대 전략에도 불구하고 지원금 등 경제적 인센티브 부족으로 인해 민간부문의 참여는 상당히 저조하다. 그럼에도 불구하고 수력에너지는 환경친화적이고 잠재성이 큰 신재생에너지로 온실가스 저감과 에너지 확보에 기여할 수 있다. 특히 수력에너지는 민간투자의 어려움이 존재하므로 정부의 장기적인 기술개발투자 및 효율성 확대 정책이 중요하다. 본 연구에서는 소수력 확대의 경제 환경적 효과를 평가해보기 위해 연산일반균형모형 (CGE :Computable General Equilibrium Model)을 구축한다. 본 연구는 다음과 같이 수행되었다. 첫째, 수력발전부문과 수도사업을 구분하고 사회회계행렬을 작성하였으며, 전력부문에서 수력발전을 포함한 다단계 생산구조를 가정하였다. 둘째, 일반균형모형 방정식 체계를 작성하고 모형의 파라미터 추정 등 보정(Calibration) 작업을 수행하였다. 셋째, 국가 중기 온실가스저감 시나리오를 적용한 전망을 수행하고 소수력 확대(투자지원) 시나리오를 구축한다. 본 연구는 저감수단으로 탄소세를 부과하였다. 끝으로, 소수력 발전 보급 확대의 경제적, 환경적 파급효과를 계산하였다. 분석결과, 소수력 발전 잠재 성장을 반영한 수력에너지 비중은 약 2020년에 약 4.5% 까지 증가하는 것으로 나타났다. 이로 인한 온실가스 저감 기여분은 약 3%에 이르는 것으로 계산 되었다. 또한 수도사업과 비에너지 제조업의 산업비중은 증가하였다. 이러한 결과는 소수력 발전 확대가 화석연료 대체를 통한 지속가능한 에너지 수요에 기여하고 지역개발과 물산업 발전 등 경제적 파급효과 등을 유발할 수 있음을 시사한다. 또한 본 연구에서 고려하지 못한 소수력 기술 개발은 에너지 대체 촉진으로 인한 온실가스 저감과 녹색성장에 기여할 것이다.

• 산업공학
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• 제23권4호
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• pp.311-318
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• 2010

In the daily multi-reservoir operating problem, monthly storage targets can be used as principal operational guidelines. In this study, we tested the use of a simple back-propagation Artificial Neural Network (ANN) model to derive monthly storage guideline for daily Coordinated Multi-reservoir Operating Model (CoMOM) of the Han-River basin. This approach is based on the belief that the optimum solution of the daily CoMOM has a good performance, and the ANN model trained with the results of daily CoMOM would produce effective monthly operating guidelines. The optimum results of daily CoMOM is used as the training set for the back-propagation ANN model, which is designed to derive monthly reservoir storage targets in the basin. For the input patterns of the ANN model, we adopted the ratios of initial storage of each dam to the storage of Paldang dam, ratios of monthly expected inflow of each dam to the total inflow of the whole basin, ratios of monthly demand at each dam to the total demand of the whole basin, ratio of total storage of the whole basin to the active storage of Paldang dam, and the ratio of total inflow of the whole basin to the active storage of the whole basin. And the output pattern of ANN model is the optimal final storages that are generated by the daily CoMOM. Then, we analyzed the performance of the ANN model by using a real-time simulation procedure for the multi-reservoir system of the Han-river basin, assuming that historical inflows from October 1st, 2004 to June 30th, 2007 (except July, August, September) were occurred. The simulation results showed that by utilizing the monthly storage target provided by the ANN model, we could reduce the spillages, increase hydropower generation, and secure more water at the end of the planning horizon compared to the historical records.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.721-727
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• 2002

Precipitation evapotranspiration and runoff are three key parameters of regional water balance. Problems exist in the traditional methods for calculating such factors , such as explaining of the geographic rationality of spatial interpolating methods and lacking of enough observation stations in many important area for bad natural conditions. With the development of modern spatial info-techniques, new efficient shifts arose for traditional studies. Guided by theories on energy flow and materials exchange within Soil-Atmosphere-Plant Continuant (SPAC), retrieval models of key hydrological parameters were established in the Yellow River basin using CMS-5 and FengYun-2 meteorological satellite data. Precipitation and evapotranspiration were then estimated: (1) Estimating tile amount of solar energy that is absorbed by the ground with surface reflectivity, which is measured in the visible wavelength band (VIS): (2) Assessing the partitioning of the absorbed energy between sensible and latent heat with the surface temperature, which was measured in the thermal infrared band (TIR), the latent heat representing the evapotranspiration of water; (3) Clouds are identified and cloud top levels are classified using both VIS and TIR data. Hereafter precipitation will be calculated pixel by pixel with retrieval model. Daily results are first obtained, which are then processed to decade, monthly and yearly products. Precipitation model has been has been and tested with ground truth data; meanwhile, the evapotranspiration result has been verified with Large Aperture Scintillometry (LAS) presented by Wageningen University of the Netherlands. Further studies may concentrate on the application of models, i.e., establish a hydrological model of the Yellow river basin to make the accurate estimation of river volume and even monitor the whole hydrological progress.

• Geomechanics and Engineering
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• 제30권5호
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• pp.401-411
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• 2022

To obtain the dynamic mechanical properties, fracture modes, energy and brittleness characteristics of Furong Baijiao coal rock, the dynamic impact compression tests under 0, 4, 8 and 12 MPa confining pressure were carried out using the split Hopkinson pressure bar. The results show that failure mode of coal rock in uniaxial state is axial splitting failure, while it is mainly compression-shear failure with tensile failure in triaxial state. With strain rate and confining pressure increasing, compressive strength and peak strain increase, average fragmentation increases and fractal dimension decreases. Based on energy dissipation theory, the dissipated energy density of coal rock increases gradually with growing confining pressure, but it has little correlation with strain rate. Considering progressive destruction process of coal rock, damage variable was defined as the ratio of dissipated energy density to total absorbed energy density. The maximum damage rate was obtained by deriving damage variable to reflect its maximum failure severity, then a brittleness index BD was established based on the maximum damage rate. BD value declined gradually as confining pressure and strain rate increase, indicating the decrease of brittleness and destruction degree. When confining pressure rises to 12 MPa, brittleness index and average fragmentation gradually stabilize, which shows confining pressure growing cannot cause continuous damage. Finally, integrating dynamic deformation and destruction process of coal rock and according to its final failure characteristics under different confining pressures, BD value is used to classify the brittleness into four grades.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.69-69
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• 2020

수자원 확보 및 홍수 대응을 위해서는 정확한 강우정보를 바탕으로 한 효율적인 댐 운영이 필요하다. 그러나 댐이 위치한 지역은 산지지역으로 강우관측소 밀도의 지역적인 편차로 인해 지상 관측 강우자료 활용 시 강우 정보의 정확도 확보에 한계가 있다. 또한, 강우의 시·공간적 변동성 심화로 기존의 강우계만으로는 정확한 강우량 추정이 어려워 이를 홍수기 댐 운영의 기초정보로 활용 시 합리적 댐 운영에 한계가 있다. 댐 운영 시 강우 관측정보는 댐 유입량 산정을 위한 강우-유출해석 모형의 입력 자료로 활용되기 때문에 강우량 자료의 정확도 확보가 무엇보다 중요하나, 현재 댐 운영에 필요한 강우 관측정보로는 지상우량계 자료가 주로 활용되고 있어 이를 보완하고자 일반적으로 강우의 공간분포를 관측할 수 있는 고해상도 레이더 강우 정보가 활용되고 있다. 본 연구에서는 전력생산(발전) 및 용수공급, 홍수조절 기능을 고려하여 운영되고 있는 한국수력원자력(주)의 수력발전용댐(팔당, 의암, 춘천, 화천, 청평, 도암, 괴산, 섬진강, 보성강댐)에 활용할 수 있도록 환경부 합성레이더 자료를 바탕으로 레이더 강우정보를 산출하고, 레이더 강우의 정확도 향상을 위해 고도영향을 고려한 레이더 강우 보정기술을 개발하고자 한다. 적용한 기법은 강우장의 공간적 구조는 레이더 자료로 획득하고, 강우량은 강우계 관측정보를 합성하는 조건부합성기법을 기본으로 하며, 고도 영향을 고려할 수 있도록 강우분포장 생성 시 주변수를 강우로, 이차변수를 고도로 정의한 표준화된 정규공동크리깅을 활용한 기법이다. 본 연구를 통해 산출된 레이더 강우를 댐 유입 측면에서 기존의 보정기법과 비교하여 정확도를 검토하고, 댐 운영에 활용할 수 있도록 유역평균강우량 정보를 산출하고자 한다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.28-28
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• 2023

Most countries worldwide are finding it difficult to make decisions regarding the utilization of water resources and the ecological flow protection of rivers because of serious water shortages and global climate warming. To overcome this difficulty, accurate ecological flow processes and protected ecological objectives are required. Since the introduction of the concept, ecological flow calculations have been developed for more than 60 years. This technical development has always been dominated by countries such as the United States, Australia, and the United Kingdom. The technical applications, however, vary substantially worldwide. Some countries, for instance, did not readjust the method because of a lack of understanding of the ecological effect or because they failed to achieve elaborate scheduling. Mostly, readjustments were not made because the users could not make their choices from among numerous methods for ecological flow. This paper presents three research results based on a systematic review of 240 methods with clear connotation boundaries. First, the ecological flow algorithm was developed along with the scientific and technological progress in the river ecosystem theory, ecohydrological relationship, and characterization and simulation of hydrological and hydrodynamic processes. In addition, the basis of the method has evolved from the hydrological process of the ecosystem, hydraulics-habitat conditions, and social development interference to whole ecosystem simulation. Second, 240 methods were classified into 50 sub-categories to evaluate their advantages and disadvantages according to the ecological flow algorithms of hydrology, hydraulics, habitat, and other comprehensive methods. According to this evaluation, 60% of the methods were not suitable for further application, including the method based on the percentage of natural runoff. Furthermore, the applicability of the remaining methods was presented according to the evaluation based on the aspects of allocation of water resources, water conservancy project scheduling, and river ecological evaluation. Third, In the future, most developing countries should strengthen the guarantee of high-standard ecological flow via a coordination mechanism for the ecological flow guarantee established under a sustainable framework or via an ecological protection pattern at the national level according to the national system. Concurrently, a reliable ecological flow demand process should also be established on the basis of detailed investigation and research on the relationship between river habitats, ecological hydrology, and ecological hydraulics. This will ensure that the real-time evaluation of ecological flow forces the water conservancy project scheduling and accurate allocation of water.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.760-767
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• 2020

발전용 수력플랜트 분야는 기후변화 및 에너지 확보를 고려해 향후 지속적인 성장이 전망된다. 수력발전설비는 항상 수충격에 의한 위험에 노출되어 있고, 이에 대한 안정성 확보는 매우 중요하다. 수충격 현상은 밸브의 개도 조정이나 펌프와 터빈의 기동 및 정지 시 관로설비 전반에 걸쳐 발생하며, 예기치 못한 긴급 상황 시에는 더욱 현저하게 나타난다. 이와 같은 수충격에 대한 발전설비의 안정성 검토를 위해 본 연구에서는 수충격 발생 메커니즘을 반영된 특성선법을 적용한 수치해석기법(MOC-FDM: Method of Characteristic-Finite Dimensional Method, 이하 MOC-FDM)을 이용하여 전산수치 모형을 개발하였다. 개발모형은 발전설비의 주요시설인 저수지, 관로, 밸브, 펌프 등 경계조건을 반영하였고 가상시나리오 case를 적용하여 개발모형을 이용한 수치모의를 수행하였다. 개발모형 해석결과의 검증을 위해 발전설비의 주요 지점에서의 해석결과를 각각 제시하였다. 각 case 별 수충격 현상이 양호하게 재현되었으며, 상용모델의 수치해석결과와 비교분석 결과가 거의 유사하게 나타나 개발모형의 신뢰성을 확인하였다. 본 연구에서 제시된 전산수치 모델은 수력발전설비의 운영 중 발생할 수 있는 비정상상태의 유체 거동을 정교하게 예측함으로써 설비의 안정성 검토를 위한 유용한 도구로 활용될 수 있을 것으로 판단된다.