• 지질공학
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• 제29권3호
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• pp.279-288
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• 2019

본 연구는 안성천에 설치된 방사형집수정에서 약 $4,000m^3/d$의 취수시 주변지역에서의 지하수위 강하량을 측정하였으며, mirror well 개념을 적용하여 계산된 지하수위 강하량과 비교 분석하였다. 지하수위 강하량의 계산은 방사형집수정을 균질 등방성 매질내의 대형 수직정으로 고려하여 실시하였다. 양수시 각 관측정에서 측정된 지하수위 강하량은 계산된 값과 약간의 오차가 발생하는데, 이는 수리전도도 및 대수층 두께 등의 이방성 때문으로 보인다. 또한, OW-7 지점은 실측 및 계산 지하수위 강하량의 차이가 약 48 cm로 크게 나타났는데, 이는 이 방향으로의 수평집수관이 설치되지 않았기 때문이다. 연구지역내에서 출현 가능한 수리전도도와 대수층 두께를 고려한 지하수위 변화의 민감도를 분석한 결과, 대수층의 두께보다는 수리전도도가 지하수위 변화에 민감하게 작용하는 것으로 나타났다. 대용량 취수 시설인 방사형 집수정의 개발시에는 배후지 수위 강하에 대한 우려가 존재하게 되므로 주변지역에 대한 대수층 특성을 정밀하게 파악하여 지하수위 변화를 예측, 평가할 필요가 있다.

• 전력전자학회논문지
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• 제11권1호
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• pp.1-6
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• 2006

본 논문에서는 유압펌프 시스템의 효율적 구동을 위한 SRM 구동시스템이 제안된다. 유압 펌프 시스템이 요구하는 최대 사용 유압 및 사용유량으로부터 적정한 용량의 SRM을 설계 및 제작하고, 시험을 위해 SRM과 제어기를 포함한 전체 유압시스템을 구성한다. 제시한 SRM 구동시스템은 효율적 구동을 위해 속도제어 뿐만 아니라 유압계통의 압력검출로부터 압력제어도 같이 행하며, 이로부터 SRM이 적정한 운전영역에서 구동되도록 한다. 2.2[KW] 12/8극 SRM과 DSP를 사용한 제어기가 설계되고, 이 시스템을 실제 유압시스템에 적용하여 운전 특성을 확인하였다. 그 결과 제안한 시스템이 고효율과 빠른 응답특성을 가짐을 알 수 있다.

• 환경영향평가
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• 제9권1호
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• pp.25-37
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• 2000

This paper presents a study of hydrological and hydraulic model applications in environmental impact statements which were submitted during recent years in Korea. In many cases (almost 70 %), the hydrological and hydraulic changes were neglected from the impact identification processes, even if the proposed actions would cause significant impacts on those environmental items. In most cases where the hydrological and hydraulic impacts were predicted, simple equations were used as an impact prediction tool. Computer models were used in very few cases(5%). Even in these few cases, models were improperly applied and thus the predicted impacts would not be reliable. The improper applications and the impact neglections are attributed to the fact that there are no available model application guidelines as well as no requirements by the review agency. The effects of mitigation measures were not analyzed in most cases. Again, these can be attributed to no formal guidelines available for impact predictions until now. A brief guideline is presented in this paper. This study suggested that the model application should be required and guided in detail by the review agency. It is also suggested that the hydrological and hydraulic items shoud be integrated with the water quality predictions in future, since the non-point source pollution runoff is based on the hydrologic phenomena and the water quality reactions on the hydraulic nature.

• 한국산학기술학회논문지
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• 제16권5호
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• pp.3081-3086
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• 2015

100톤급 굴삭기에 장착할 수 있는 초대형 유압브레이커 개발을 수행하였다. 유압브레이커 설계에 앞서 타격에너지, 분당 타격수 등의 성능을 예측할 수 있는 유압브레이커 해석 방법에 대해 연구하였다. 해석 결과를 바탕으로 초대형 유압브레이커의 설계 및 제작이 이루어졌으며, 유압브레이커가 성공적으로 작동함을 확인하였다. 실제 유압브레이커 작동 시 타격에너지와 분당 타격수를 측정하여, 해석 결과와 비교하였다. 분당 타격수 해석 결과는 큰 오차 없이 실험 결과를 잘 예측하였지만, 타격에너지 해석 결과는 실제 실험 결과와 매우 큰 차이가 나타남을 확인하였다. 초대형 유압브레이커를 성공적으로 개발하였으며, 향후 마찰, 유압회로 등을 고려하여 타격에너지 해석 방법을 보완할 예정이다.

• 한국환경과학회지
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• 제32권5호
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• pp.303-313
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• 2023

In this study, the hydraulic gradient was calculated using the groundwater level and rainfall observed in the Hyogyo-ri area for a year, and the change in the hydraulic gradient according to the rainfall was analyzed. It was found that the groundwater level increased as the rainfall increased in all groundwater wells in the research site, and the groundwater level rise decreased as the altitude of the groundwater well increased. The hydraulic gradient in the research site ranged from 0.016 to 0.048, decreasing during rainfall and increasing after the end of the rainfall. As the rainfall increased, the groundwater level rise in the low-altitude area was more than the high-altitude area, and the hydraulic gradient decreased due to the difference in groundwater level rise according to the altitude. Through this study, it was found that the influence of rainfall is dominant for the fluctuation of the hydraulic gradient in the unconfined aquifer.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.36-44
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• 2006

Based on water resources availability and development condition of the Lancang River, as well as considering the international river water resources characters, the paper put forwarded an integrated allocation way of the water resources of Lancang River Basin. According to the basic rules of equitable and suitable utilization of water resources of international rivers, water resources demand for domestic, industrial, irrigation and ecosystem system, and principles of society stabilities and the food safety etc, an index system of Lancang River water resources allocation was set up. Two levels scheme of Lancang River water allocation are proposed. First level is for an international water, which primarily to analysis the water quantity at the national boundary. Second level is for provincial water allocation among Qinghai, Yunnan provinces and Tibetan Autonomous Region. In the allocation schemes, the water resources development of Lancang River Basin at different scenarios and the related water allocation in different years and seasons were analyzed. A discharge to some cross sections of the river and a total amount water quantity for each district has been given as well.

• 대한기계학회논문집B
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• 제30권1호
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• pp.87-94
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• 2006

This paper presents the hydrodynamic design and performance analysis method for a miniaturized centrifugal blood pump using three-dimensional computational fluid dynamics (CFD) code. In order to obtain the hydraulically high efficient configuration of a miniaturized centrifugal blood pump for cardiopulmonary circulation, a well-established commercial CFD code was incorporated considering detailed flow dynamic phenomena in the blood pump system. A prototype of centrifugal blood pump developed by the present design and analysis method has been tested in the mock circulatory system. Predicted results by the CFD code agree very well with in vitro hydraulic performance data for a centrifugal blood pump over the entire operating conditions. Preliminary in vivo animal testing has also been conducted to demonstrate the hemodynamic feasibility for use of centrifugal blood pump as a mechanical circulatory support. A miniaturized centrifugal blood pump developed by the hydraulic design optimization and performance prediction method presented herein shows the possibility of a good candidate for intra and extracorporeal cardiopulmonary circulation pump in the near future.

• International Journal of Fluid Machinery and Systems
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• 제2권4호
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• pp.383-391
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• 2009

Vibrations at different frequencies with a different intensity as well as a pressure pulsation with different parameters are two phenomena which can be observed at different water turbines. Due to the vibration and the pressure pulsation some restrictions of water turbine operation range are applied. Similar problems with the efficiency level in a wide water turbine operation range are the basic problems which are solved for ages. A theoretical and practical solution of the above mentioned problems is very much time and money consuming. The paper describes a new theoretical solution of the excitation and pressure pulsation decrease as well as extension of the operational range with high efficiency level. The new concept to decrease the vibrations and pressure pulsations is based on a heterogeneous runner blade geometry generation. The new concept of the runner geometry design was numerically tested at a low specific speed pump turbine, see Fig. 1, and basic points of the concept are presented in this paper.

• 지질공학
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• 제4권2호
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• pp.219-229
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• 1994

균열 암반내 지하수 흐름은 공간적으로 불규칙하게 분포하는 균열 발달 상태에 영향을 받으므로 균질의 등방성 피압 대수층에 적용이 가능한 Theis식으로는 균열 암반 대수층의 수리지질학적 특성을 똑바로 이해할 수 없다. 본 연구에서는 지하수 흐름의 프락탈(Fractal)모델을 발전시킨 누수를 포함하는 프락탈모델의 이론적은 배경 및 수리상수 산출 방법을 제시하고,개발된 모델을 야외자료에 적용시켰다. 상기 모델은 홍천과 유성지역에서 수행된 양수시험 자료에 적용시킨 결과, 동일한 수리상수 값으로 양수정과 관측정에서의 관측된 수위하강 곡선과 이론적인 수위하강 곡선이 잘 일치하는 결과를 얻었다. 홍천 지역과 유성 지역의 시험공 주위의 프락탈 차원은 1.9로 구해졌으며, 이것은 이들 지역의 지하수 흐름이 2차원보다 약간 작은 프락탈 차원을 보인다는 것을 지시한다.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.1126-1135
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• 2022

The MARS code has been assessed for the prediction of onset of flow instability (OFI) in a vertical channel. For assessment, we built an experiment database that consists of experiments under various geometry and thermal-hydraulic condition. It covers pressure from 0.12 to 1.73 MPa; heat flux from 0.67 to 3.48 MW/m²; inlet sub-cooling from 39 to 166 ℃; hydraulic diameters between 2.37 and 6.45 mm of rectangular channels and pipes. It was shown that the MARS code can predict the OFI mass flux for pipes reasonably well. However, it could not predict the OFI in a rectangular channel well with a mean absolute percentage error of 8.77%. In the cases of rectangular channels, the error tends to depend on the hydraulic diameter. Because the OFI is directly related to the subcooled boiling in a flow channel, we suggest a modified subcooled boiling model for better prediction of OFI in a rectangular channel; the net vapor generation (NVG) model and the modified wall evaporation model were modified so that the effect of hydraulic diameter and heat flux can be accurately considered. The assessment of the modified model shows the prediction of OFI mass flux for rectangular channels is greatly improved.