• Geomechanics and Engineering
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• 제29권5호
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• pp.583-598
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• 2022

The Compaction effect is important for evaluating the subgrade construction. However, there is little research exploring the compaction quality of deep soil using hydraulic compaction. According to reinforcement effect analysis, dimensional analysis is adopted in this work to analyze subgrade compactness within the effective reinforcement depth, and a prediction model is obtained. A hydraulic compactor is then employed to carry out an in-situ reinforcement test on gravel soil subgrade, and the subgrade parameters before and after reinforcement are analyzed. Results show that a reinforcement difference exists inside the subgrade, and the effective reinforcement depth is defined as increasing compactness to 90% in the depth direction. Layered compactness within the effective reinforcement depth is expressed by parameters including the drop distance of the rammer, peak acceleration, tamping times, subgrade settlement, and properties of rammer and filler. Finally, a field test is conducted to verify the results.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.340-345
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• 2003

Cryogenic turbopump test facility(CTTF) is designed and developed. Hydraulic and cavitation performance of turbopump in cryogenic environment can be measured. Working fluid is liquid nitrogen and operating temperature is $-197^{\circ}C$. Liquid nitrogen run tank, catch tank and pressurizing tank has been built and remote tank pressure control system are installed. Maximum power of turbopump is 320kW and its maximum speed is 32000rpm. Cryogenic fluids and lubricating systems are effectively separated that long test times are acquired. Therefore hydraulic and cavitation performance can be measured accurately and effectively. This facility will contribute greatly to the development of turbopump for KSLV.

• 한국기계가공학회지
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• 제21권2호
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• pp.73-78
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• 2022

The test apparatus that can be protected from the high-temperature combustion flame and coolant injection was successfully manufactured. In this study, the coolant-injection module had a controllable consistent pressure, and the entire combustion module was protected using a nonflammable composite liner. Every flange was designed in accordance with the DIN standard, and the entire body of the module was designed in accordance with the EN 13445 code. Additionally, the hydraulic pressure test was performed in accordance with the 2014/68/EU directive and EN 13445 standard. Finally, after manufacturing, performance tests (such as pressure tests) were conducted to verify the reliability and safety.

• 대한환경공학회지
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• 제22권5호
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• pp.927-938
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• 2000

박테리아를 토양과 같은 다공성 매질에 주입시키고 적절한 기질과 영양분을 공급시키면 박테리아는 매질의 표면에 부착하여 성장한다. 그 결과 바이오필름이 생성되어 공극의 크기가 감소하여 매질의 투수계수가 감소되며, 오염물질을 분해시키는 생물학적 오염분해 능력을 갖게 된다. 본 연구는 투수계수가 비교적 큰 모래와 화강풍화토에 박테리아를 접종, 배양한 후 토양의 투수계수의 변화를 측정하였으며, 배양된 바이오필름의 화학물질에 대한 저항성 및 온도변화에 대한 내구성 실험을 통해 대용 차수재로의 가능성을 평가하였다. 또한 bio-barrier의 유기물질 분해능 및 bio-barrier의 두께에 따른 미생물의 생장도를 column test를 통하여 측정하여 bio-barrier 내에서의 기질의 이동 및 생분해와 박테리아 농도의 분포 변화간의 관계를 제시하였다.

• Journal of Biosystems Engineering
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• 제34권5호
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• pp.305-314
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• 2009

The purpose of this paper was to design an effective control system of 1-axis exciter for a seat vibration test of agricultural tractors using MATLAB simulation. The developed simulation model was composed with a hydraulic pump, a hydraulic servo valve, a hydraulic cylinder and load system. Also it was verified by comparing the simulation results with experimental results of actual control system in order to optimize the control performance. And in order to improve its control performance, the designed PID controller in this research was tuned using Ziegler-Nichols 2nd law and zero's moving method of PID controller's transfer function. As the result of these research, the developed position control system was able to control the system's position accurately within 5% errors.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.687-697
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• 2010

This study was designed to carry out studies on critical seepage velocity and critical hydraulic gradient using a piping test targeting SM and ML which are widely distributed ahead of and behind the depth of E.L(-)10m in Saemangeum area in order to examine stability of embankment built on the ground vulnerable to piping. The effects of relative densities on critical hydraulic gradient and critical velocity were also compared and analyzed using empirical formula and theoretical formula, and relative densities were set up as respectively 9%, 25%, 50%, and 75% for this experiment. As a result, for critical hydraulic gradient, most of specimens detected piping at lower values than the empirical formula of Terzaghi(1922). It is, therefore, considered that the empirical formula devised by Kalin(1977) or Hayashi(1978) is more reasonable to be conservative. It was also found that critical velocity decreased as relative density increased, and critical velocity predicted was mostly lower than the theoretical formula.

• 한국유체기계학회 논문집
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• 제6권3호
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• pp.51-57
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• 2003

Characteristics of the high frequency pulsatile flow have been investigated experimentally to understand the flow phenomena in the hydraulic system. One axis fatigue test bed, which is widely used for automobile field test, is used. Four pressure transducers, an amplifier and a A/D convertor are used to obtain the high frequency pulsatile pressure waveform in hydraulic system. The characteristics of frequency are analyzed by power spectrum method. According to the variations of pump input pressure and actuator acceleration frequency, the pressure is measured with or without an accumulator. The amplitude of pressure with accumulator is very lower than those without accumulator due to absorbing function of accumulator. As the frequency of actuator acceleration is increased, the effect of accumulator become very important to decrease the amplitude of pulsatile pressure waveform with high frequencies.

• 한국산업융합학회 논문집
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• 제13권1호
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• pp.15-22
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• 2010

This paper was originated to set up a test equipment and to obtain the proper installation condition of the plastic damper for the hydraulic clutch control system. Performance tests with different specifications have been applied to the damper to investigate the workability and the vibration characteristics of each case, and the result was utilized into the system simulation for the optimal condition for the damper. The procedure has been developed to set up a damper test system to analyze the dynamic properties and the operation of the system, and further to setup a simulation program for the realistic situations. The result can also be applied to the dampers and the clutch systems to be developed in the future for the property tests and the optimization of the installation conditions.

• 산업기술연구
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• 제26권B호
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• pp.63-71
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• 2006

The concerned object of the construction industry is environment. It is one of the main purposes of today's construction that human can live reasonably in nature. This study is about the fish-road connecting hydraulic structure in the river with nature. Chapter 2, starting with the general investigation about fish-road and helps comprehension for relatively general fish-road such as necessity, establishment purpose, history, study example, relating domestic law, design condition, consideration and form of fish-road. Chapter 3, containing the present condition of fish-road facilities in Gangwon-Do and thoughts of the problems and general countermeasures of existing fish-road. Chapter 4, Having Examined compatibility by amount of flowing water through hydraulic model test in the Ice harbor I-type model. chapter 5, Analyzation and arrangement to efficient establishment plan of fish-road and the result of the hydraulic model experiment to be beaconed a little in forward fish-road study. In the hydraulic model test result, when we suppose establishment of 1~3 in slope of 1/20, could know that applicable drought flow of the river is $0.06{\sim}3.0m^3/sec$ in case of Ice harbor I-type which transforming Ice harbor that was invented as studying project of the Ministry of Environment.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.284-287
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• 2005

The flow of groundwater in fractured medium is related to the geometric characteristics of the fracture system. And a fracture aperture and a fracture density are considered as important factor concerning the permeability. Data acquisition of the properties of fracture such as aperture and density is so difficult and has uncertainty. We also cannot know the fracture characteristics through the in-situ tests. We usually obtain the fracture information from a ultrasonic scan logging or borehole television indirectly. Using the deduced results, we can make the fracture system and simulate the groundwater flow and solute transport in the crystalline rock. This study aimed to analyze the correlation between the properties of fracture and hydraulic conductivities obtained at the same interval. The properties of fracture are examined by acoustic televiwer and hydraulic conductivities are obtained by constant Pressure injection test. The distributioin of fracture width and fracture frequency shows the log-normal probability plot. And, Results of correlation analysis explain that opened type fractures have proper relation with hydraulic conductivity. But, as though there are semi-opened type fractures or closed type fractures, those have the permeable structure.