• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.144-169
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• 2010

In 2002, property loss caused by failure or leakage of existing river levee structures was about 1.8 trillion in Korean Won, and furthermore in which damages of river structures are getting more severe due to characteristics of extremely extraordinary rain such as torrential rain in the locality or guerrilla heavy rain. In this regards, this paper collects and analyzes those damage records and costs for repair by statistic method, and moreover categorizes the causes of failure, erosion and overtopping of levee structures in large and small scale rivers threatened frequently by typhoon and heavy rainfall. It is believed that the results from the analyses can be used as a basic source in developing criteria of standards for design, construction, maintenance and inspection(or diagnosis) of hydraulic structures such as levee and drain conduit.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1-4
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• 2005

This paper describes work on isolation of vibration related engine by a hydraulic engine mount with controllable area of inertia track. Automotive engine mounts are required to constrain motion of engine shake resulting from low-frequency road input of shock excitation and also to isolate noise and vibration generated by the engine with unbalanced disturbance at the high frequency range. The property of the mount depends on vibration amplitude and excitation frequency, which means that the excitation amplitude is large in low excitation frequency range and small in high frequency range. In this paper, theoretical works with model of the mount to reduce vibrations related engine were conducted. The volumetric stiffness of the mount is greatly changed according to the switching the area of the inertia track. Therefore, when the area of the inertia track is tuned, the transmissibility of the mount is effectively reduced.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.170.1-170
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• 2001

This paper developed the model for electro hydraulic force control system by identification method via ARMAX model. Implementation of Identification is performed on Pin-On-Disk type tribotester. The wear mechanism is an important mechanic property to select a material´s life and a optimum work condition. Pin-on-disk type tribotester is popular wear analysis experimental equipment and its mechanism is that adding a force on a rotating disk to simplify two surface contact´s wear experimental condition. Material´s rotating velocity and eccentricity rotation makes disturbance and it affects adding constant force. To get a high performance of force adding part, DDV(Direct Drive Valve) which has pressure control loop is used. To obtain a tribotester´ s ARMAX model, prediction error method(PEM) is used in case force adding part and rotating part is ...

• Geomechanics and Engineering
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• 제29권1호
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• pp.1-11
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• 2022

A semi-analytical solution to responses of overconsolidated (OC) unsaturated soils surrounding an expanding spherical cavity under constant suction condition is presented. To capture the elastoplastic hydro-mechanical property of OC unsaturated soils, the unified hardening (UH) model for OC unsaturated soil is adopted in corporation with a soil-water characteristic curve (SWCC) and two suction yield surfaces. Taking the specific volume, radial stress, tangential stress and degree of saturation as the four basic unknowns, the problem investigated is formulated by solving a set of first-order ordinary differential equations with the help of an auxiliary variable and an iterative algorithm. The present solution is validated by comparing with available solution based on the modified Cam Clay (MCC) model. Parametric studies reveal that the hydraulic and mechanical responses of spherical cavity expanding in unsaturated soils are not only coupled, but also affected by suction and overconsolidation ratio (OCR) significantly. More importantly, whether hydraulic yield will occur or not depends only on the initial relationship between suction yield stress and suction. The presented solution can be used for calibration of some insitu tests in OC unsaturated soil.

• 대한환경공학회지
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• 제28권6호
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• pp.626-633
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• 2006

본 연구는 부천시를 대상으로 지하수의 함양량, 대수층의 수리학적인 특성, 심도 및 지하수 심도에 따른 수리, 화학적 특성, 지하수의 오염특성을 파악하기 위해 수행되었다. 수리시험의 대상공은 부천지역의 토지이용형태와 도시발달을 고려하여 충적층 2개 지점과 암반층 9개 지점, 총 11개 지점을 선정하여 양수시험과 함께 회복시험을 동시에 실시하였다. 대수층의 투수량계수, 수리전도도 등의 수리상수를 도출하기 위해 양수시험은 충적층은 Theis의 해법에 의해 해석하였으며 암반층은 Theis의 회복해법에 의해 해석하였다. 학교운동장, 녹지공간이 확보된 공원 지역내 양수정은 지하수량이 다른 지역보다 풍부하고, 투수량계수와 수리전도도가 높은 값을 보였는테 이 지역이 강수의 수직침투와 수평이동이 활발하여 도시지역에서 주요 지하수 함양지역임을 뒷받침한다. 도심권의 도로 및 건축물에 의해 포장된 지역 양수정에서는 수리상수 값이 낮아 지하수의 함앙이 어려운 지역으로 관찰되었다. 부천지역 48개 지점에서 채수한 지하수는 심층기반암이 화성암에 기인하여 지하수가 약산성화된 특성을 보였다. 부천시의 지역별 전기전도도는 $70.4{\sim}1,287{\mu}S/cm$의 범위를 보였으며 용해성 광물이나 일부 탄산염의 영향을 받아 대부분의 지역에서 다소 높게 검출되었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.378-381
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• 2008

The buckling behavior of cylindrical shape-memory alloy and aluminum tube is investigated at room temperature using a split Hopkinson pressure bar and an Instron hydraulic machine with a specially designed recording system. The shape-memory alloy at superelastic property regime buckles gradually in quasi-static loading, and fully recovers upon unloading. However, the buckling of aluminum tube is sudden and catastrophic, and shows permanent deformation. This gradual buckling of shape-memory alloy is associated with the forward and reverse transformation of stress-induced martensite and seems to have a profound effect on the unstable deformation of tube structures made from shape-memory alloy.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.555-559
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• 2001

A by-product, waste sludge water produced from ready mixed concrete(remicon) factories may affect our environmental contamination if it is discharged without proper waste disposal. In Korea, all waste sludge water has been recycled in the way of mixing water of remicon, but the quality of the concrete then produced can be deteriorated, so it might cause slump loss or irregular compressive strength. In this study, waste sludge water is divided into two parts, remicon sludge and residual water in order to make it's property more stable. Then, the remicon sludge and high-alkaline residual water were used as admixture and alkali activator respectively. In this paper we research about quality of with remicon sludge and residual water and performed the fundamental properties of cement matrix mixed with remicon sludge and residual water.

• 자원리싸이클링
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• 제24권1호
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• pp.12-20
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• 2015

본 연구에서는 고로 수쇄 슬래그 및 석고를 혼합한 3성분계 천연 수경성 석회 페이스트에서 석고종류 및 혼합량에 따른 수화특성 변화를 확인하고자 하였다. 고로 수쇄 슬래그 20 %를 혼합한 천연 수경성 석회에 무수석고, 반수석고, 이수석고를 각각 3 %, 10%를 혼합하여 석고의 용해도 및 반응성에 따라 수화초기 생성되는 수화물의 종류와 생성량을 분석하였으며, 이에 따른 물리적 특성 변화거동에 대하여 조사하였다. 페이스트를 활용한 수화특성 결과 모든 샘플에서 수화초기 ettringite, C-S-H와 같은 수화물이 생성되었으며, 재령이 길어짐에 따라 수화물의 생성량이 증가하였다. 압축강도 측정결과, 석고 혼합량이 3 %일 때 더 높은 강도를 보였으며 재령 28일에서 무수석고 및 반수석고가 이수석고를 혼입할 경우 보다 높은 특성을 나타내었다.

• 지질공학
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• 제16권2호
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• pp.125-134
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• 2006

대수층 저류 특성을 이용하는 대수층 저장 및 회수(ASR) 기술의 현장 적용성 평가를 위해 화산암 지대인 울릉도 내에 다공성 매질인 부석층으로 이루어진 대수층을 대상으로 양수시험 및 인공수압파쇄시험을 실시하였다. 공내TV검층에서 확인된 GL-13 m와 GL-21 m의 주파쇄대 구간에서 수압파쇄실험을 각각 실시하였고, 또한 수압파쇄 전과 후로 나누어 양수시험을 수행하였다. 사전/사후 양수시험 결과, 충적층이 위치한 GL-13 m 하부에서는 수리적 연결성을 확인할 수 있었으나, 암반층 구간인 GL-21 m 하부에서는 파쇄대의 연결 상태가 다소 불량한 것으로 판단된다. 현장시험 결과를 종합해 보면, 조사지역내 인공함양 적용은 불리한 조건을 가지는 것으로 판단되나, 현장 실험이 특정한 지역에서 이루어져 있기 때문에 울릉도 전반적인 지역 내에 ASR 적용성 평가를 대표할 수 없다. 따라서 울릉도내 전반적인 ASR 적용성 평가를 위해서는 보다 광역적인 실험이 수행되어야 할 것으로 판단된다.

• 한국건축시공학회지
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• 제8권4호
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• pp.79-85
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• 2008

The purpose of this study is to evaluate the mix design of pH reducing cement concrete which can be used for environment-friendly concrete. Cement pastes and concretes are prepared with water-binder ratios and various admixtures such as blast-furnace slag, fly ash and recycled cement, and tested for compressive strength and pH. pH is measured through pore solution expressed from hydrated cement paste by special apparatus. From the test results, regardless of water-binder ratio, The pH of expressed pore solution from hydrated cement paste which is made of ordinary portland cement with blast-furnace slag, fly ash is decreased with increasing of admixtures content, and compressive strength is also slightly improved. The compressive strength of cement paste made of recycled cement which is burnt at $1000^{\circ}C$, for 2 hours is considerably increased compared with that of none-burnt recycled cement due to restoration of hydraulic property, but pH is a little higher. Porous concrete with ordinary portland cement has high pH in the range of 12.22 to 12.59, however, that is reduced to the range of 8.95 to 10.39 by carbonation at the surface of porous concrete. The pH reduction of porous concrete is possible by various admixture addition, however their degrees are very slight. Therefore, to reduce the pH considerably, carbonation method of porous concrete is better in pH reduction methods for plant survival condition of pH of 9.0 or less. In this study, it is apparent that pH for the environment-friendly porous concrete products used in the construction field can be suppressed by this carbonation method and various admixtures addition.