• 터널과지하공간
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• 제18권2호
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• pp.91-97
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• 2008

본 고에서는 공동굴착에 따른 주변 영향영역 암반의 투수 특성 변화를 간접적 방법이 아닌 직접적으로 측정 가능한 현장수리시험장비를 소개하고 국내 지하연구시설(URL) 현장실험에 적용한 결과를 수록하였다. 굴착공동 주변 수리학적 EDZ의 투수계수 측정의 정밀도 향상을 위해서는 잘 설계된 시험장비와 함께 시험결과를 분석 평가하는 기술이 통합된 시스템 개발이 필요할 것으로 생각된다. 이를 통해 지하수면 아래 건설되는 공동의 안정성 평가, 방배수 시스템 및 그라우팅 설계의 신뢰도 향상에 기여할 수 있을 것으로 기대된다.

• 지질공학
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• 제24권2호
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• pp.201-215
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• 2014

본 연구에서는 창원시 강변여과수 개발사업(2단계)에서 얻어진 자료들을 이용하여 대수층의 수리전도도와 방사형집수정의 수평집수관에서 산출되는 유량과의 상관관계를 규명하고자 하였다. 연구지역인 낙동강 중하류 모래자갈층에서 수평적으로 채취한 미고결 퇴적물의 시료를 이용하여 경험식에 의한 수리전도도를 산정하였다. 여러 경험식을 이용하여 연구지역에서 수리전도도를 산정한 결과, Beyer식에 의한 수리전도도가 가장 적합한 것으로 판정되었다. 산정된 수리전도도는 0.083 ~ 0.264 cm/s의 범위, 평균 0.159 cm/s로 나타내고 있어 연구지역의 대수층 특성은 모래자갈층에 투수성이 양호한 것으로 나타났다. 산정된 수리전도도와 실측자료에 의한 스크린 내 지하수의 유입속도 및 유량과의 상관관계를 분석하고자 회귀분석을 실시하였다. 회귀분석 결과, 수리전도도와 지하수의 유입속도 및 유량은 약 72 %의 높은 상관관계를 가지는 것으로 나타났고, 각 변수들 간에 실측자료와의 검증에서도 약 72 %가 일치하는 것으로 분석되어 선형 회귀식은 높은 적합성을 나타내었다. 본 연구의 결과로서 선형 회귀식을 이용하여 수리전도도에 의한 방사형집수정의 수평집수관에서 산출되는 유량의 추정이 가능하고, 연구지역과 유사한 대수층에서 적용이 가능할 것이라고 사료된다.

• Geomechanics and Engineering
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• 제6권2호
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• pp.153-172
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• 2014

In order to investigate the effect of different perforation angles (the angle between the perforation direction and the maximum horizontal principal stress) on the fracture initiation and propagation during hydraulic fracturing of highly deviated well in oil & gas saturated formation, laboratory experiments of the hydraulic fracturing had been carried out on the basis of non-dimensional similar criteria by using 400^3 $mm^3$ cement cubes. A plane fracture can be produced when the perforations are placed in the direction of the maximum horizontal principal stress. When the perforation angle is $45^{\circ}$, the fractures firstly initiate from the perforations at the upper side of the wellbore, and then turn to the maximum horizontal principal stress direction. When the well deviation angle and perforation angle are both between $45^{\circ}$ and $90^{\circ}$, the fractures hardly initiate from the perforations at the lower side of the wellbore. Well azimuth (the angle between the wellbore axis and the maximum horizontal principal stress) has a little influence on the fracture geometries; however it mainly increases the fracture roughness, fracture continuity and the number of secondary fractures, and also increases the fracture initiation and propagation pressure. Oriented perforating technology should be applied in highly deviated well to obtain a single plane fracture. If the well deviation angle is smaller, the fractures may link up.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1582-1596
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• 2005

Groundwater flow and behavior have to be investigated based on heterogeneous subsurface formation since the homogeneity assumption of this formation is not valid. Over the past twenty years, stochastic approach and Monte Carlo technique have been utilized very efficiently to understand the groundwater flow behavior. However, these techniques require lots of computational and numerical efforts according to the various researchers' comments. Therefore, utilizing new techniques with much less computational efforts such as Artificial Neural Network (ANN) in the prediction of the stochastic behavior for the groundwater based on heterogeneous subsurface formation is highly appreciated. The current paper introduces the ANN technique to investigate and predict the stochastic behavior of a well draw down in a confined aquifer based on subsurface heterogeneous hydraulic conductivity. Several ANN models are developed in this research to predict the unsteady two dimensional well draw down and its stochastic characteristics in a confined aquifer. The results of this study showed that ANN method with less computational efforts was very efficiently capable of simulating and predicting the stochastic behavior of the well draw down resulted from the continuous constant pumping in the middle of a confined aquifer with subsurface heterogeneous hydraulic conductivity.

• 보존과학회지
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• 제34권4호
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• pp.295-303
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• 2018

The application of reinforcing agents with hydraulic property and strength development characteristics was studied under conditions similar to those of mural-painting mortar made with oyster shell powder. Reinforcement mortar made with oyster shell powder showed hydraulic properties and strength to supplement the weaknesses of natural hydraulic lime(NHL); this confirmed its possibility as a wall-reinforcing material with enough strength for preserving mural paintings. Reinforcement mortar 1 showed hydraulic property and general characteristics of lime mortar, such as consistency and viscosity, as well as lower strength and higher whiteness compared to an NHL product. For Reinforcement mortar 2, the original wall sample characteristics were reflected by mixing more shell produced through calcination; and it showed similar strength to that of Reinforcement mortar 1 as well as high whiteness. In measuring the contraction ratio of reinforcement mortar samples, Reinforcement mortar 1 and 2 showed more stability in property change compared to the NHL Group.

• International Journal of Automotive Technology
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• 제8권6호
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• pp.791-798
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• 2007

The hydraulic hybrid vehicle(HHV) is an application of hydrostatic transmission technology to improve vehicle fuel economy and emissions. A relatively lower energy density of hydraulic accumulator and complicated coordinating operations between two power sources require a special energy management strategy to maximize the fuel saving potential. This paper presents a new type of configuration for parallel HHV to minimize the disadvantages of the hydraulic accumulator, as well as a methodology for developing an energy management strategy tailored specially for PHHV. Based on an analysis of the optimal energy distribution between two power sources over a representative urban driving cycle with a Dynamic Programming(DP) algorithm, a fuzzy-based optimal torque management strategy is designed and developed to control the torque distribution. Simulation results demonstrates that the optimal torque management strategy maximizes the advantages of this hybrid type of configuration, and the high power density characteristics of hydraulic technology effectively improve the robustness of the energy management strategy and fuel economy of the PHHV.

• 한국정밀공학회지
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• 제20권8호
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• pp.94-100
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• 2003

This paper presents the experiments on the approximation of a hydraulic servo system using a real time recurrent neural networks (RTRN) with time varying weights. In order to verify the effectiveness of the RTRN algorithm in hydraulic servo system, we design the experimental hydraulic system and implemented the real time approximation of system output. Experimental results show that approximated output of the RTRN well follows the position trajectory of the electro-hydraulic servo system. And also it is verified that the 2-D RNN can be implemented in sampling time even though high sampling frequency experimentally.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.365-366
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• 2006

Hydraulic circuit breaker is the most popular type of electric power circuit breaker because of its superiority of operating performance and capacity. For the improvement of hydraulic circuit breaker's operating performance, it is very important to analyze its dynamic behavior characteristics. In this study, hydraulic circuit is modeled, analyzed and experimented. As a result, the experimental data agree well with the numerical ones, and the numerical results can be applied to the design and the improvement of hydraulic electric power circuit breaker.

• Journal of Biosystems Engineering
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• 제31권2호
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• pp.88-94
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• 2006

The market of rice transplanter has already been changed for riding and to be turned large size of chassis. Because an automation is rapidly expanded, It is strongly need to analyze a mechanism and develop a hydraulic circuit. In this study, we analyzed the mechanism of working equipment of rice transplanter for riding and developed hydraulic circuits. We proposed the operating mechanism of rice transplanter for riding through the mechanistic analysis of working equipment. And the simulation and experiment were performed. In order to up and down the working equipment of rice transplanter for riding, we designed the mechanism which was installed hydraulic circuit and hydraulic cylinder, and it was manufactured. The pressure of developed hydraulic circuit was set by 800 $N/cm^2$. In the field testing, the hydraulic response presented at 50 msec in the maximum driving velocity, 0.8 m/sec of rice transplanter for riding, and it was well performed. The results of experiments showed the system characteristics sufficient to use as the hydraulic mechanism for a rice transplanter for riding.

• International Journal of Control, Automation, and Systems
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• 제1권4호
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• pp.484-494
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• 2003

In this paper, we describe a hydraulic system design and vehicle dynamic modeling for development of tire roller traction, an essential aspect in the system analysis of tire rollers. Generally, tire rollers are one of the most useful types of machines employed in road construction, technically applied to many construction fields. We also conceptualize a new hydraulic and driving system as well as define the motion equations for dynamic and hydraulic analysis. First, we design the hydraulic circuit of the steering control and driving machine system, which can be employed to advance the performance of the lateral control, creating a prototype of construction equipment. Second, we formulate the hydraulic steering system model and hydraulic driving system model through tire roller system development technology. Finally, we validate the acquired performance results in actual tire roller equipment using the data acquisition system. These results may perhaps facilitate the establishment of priorities and design strategies for incremental introduction of tire roller technology into the vehicle and construction field.