• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
• /
• pp.302-305
• /
• 2009

The Francis type hydro turbine with vertical axis has been designed and analized for hydraulic performance verification. The guide vane angle of turbine casing were designed to be varied according to the condition of head and flowrate. When the changes in flowrate and output were comparatively large, the efficiency drop were small, so the efficiency characteristics and stability of the entire operating condition were maintained in good condition. These results showed that the developed hydro turbine in this study will be suitable for small hydro power stations with medium and high head such as agricultural reservoirs and large dam.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
• /
• pp.167-171
• /
• 2008

The Francis type hydro turbine with vertical axis has been designed and analized for hydraulic performance verification. The guide vane angle of turbine casing were designed to be varied according to the condition of head and flowrate. When the changes in flowrate and output were comparatively large, the efficiency drop were small, so the efficiency characteristics and stability of the entire operating condition were maintained in good condition. These results showed that the developed hydro turbine in this study will be suitable for small hydro power stations with medium and high head such as agricultural reservoirs and large dam.

• International Journal of Fluid Machinery and Systems
• /
• 제1권1호
• /
• pp.86-91
• /
• 2008

The effects of the diffuser vane on the performances of the multistage centrifugal pump were investigated experimentally, taking account of the interactions among the diffuser vane, the return vane, and the next stage impeller. It is very important to match well the diffuser vane with the return vane, for improving the hydraulic efficiency of the pump. The efficiency may be more improved by making the cross-sectional area of the channel from the diffuser vane outlet to the return vane inlet larger, as much as possible.

• 드라이브 ㆍ 컨트롤
• /
• 제13권3호
• /
• pp.53-66
• /
• 2016

New non-hybrid approaches to improve energy efficiency of construction machineries are reviewed in this paper. Hydraulic systems are classified into four classes according to Backe's classification and commercially promising new technologies are carefully chosen in each class. IMV, 3-Line CPR, Closed Circuit Displacement Control of Differential Cylinder, and Throttle-less Secondary Control are chosen as representative non-hybrid new technologies. Key principle of each technology is explained and representative references which run through each technology are selected. Advantages and weaknesses of each technology are discussed and compared from the view point of construction machinery manufacturers.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2008년도 추계학술대회 논문집
• /
• pp.379-382
• /
• 2008

The propeller type hydro turbine model with vertical axis has been tested and analized. The blade angle of runner of turbine model were designed to be varied according to the condition of head and flowrate. When the changes in head and output were comparatively large, the efficiency drop were small, so the efficiency characteristics and stability of the entire operating condition were maintained in good condition. These results showed that the developed model in this study will be suitable for small hydro power stations with large changes in head and load such as sewage treatment plants and agricultural reservoirs.

• Tribology and Lubricants
• /
• 제20권3호
• /
• pp.157-162
• /
• 2004

The cam curve of a balance type vane pump consists usually of circular arcs and Archimedes' spirals. However, if they are connected directly together, the curve must have a few discontinuous points of the gradients and the motion of the vanes is no longer smooth. Designing data for an oil hydraulic vane pump used in power steering system were obtained by the acquisition of optimum cam profile data which can be available to reduce noises and vibrations through the minimization of cavitation with the improvement of suctional performance. The performance test is carried on the trial manufactures by measuring the volumetric and the mechanical efficiency. And from that result, maintaining the same characteristic as the conventional one in the relief pressure and noise level, the experimental pump discharges 0.7 $\ell$/min and shows nearly 3.5% enhancement in the total efficiency more than the conventional one.

• 한국습지학회지
• /
• 제3권1호
• /
• pp.75-89
• /
• 2001

Constructed wetlands were typically cost less to build and operate, and require less energy than standard mechanical treatment technology but they have similar performance to centralized wastewater treatment plants. Therefore, they were constructed especially many in rural areas, where are small villages but not industries. Accordingly, plantless column tests were performed to investigate the possibility on using zeolite as a filter medium of constructed wetland for the wastewater treatment. $COD_{cr}$ removal efficiency was 94.63% at hydraulic load $314L/m^2{\cdot}d$ and filtering hight 100cm filled with a zeolite mixture. This zeolite mixture consisted of 1 : 1 by volume of a zeolite in the diameter range of 0.5 to 1mm to a zeolite in the diameter range of 1 to 3mm. According, hydraulic load $314L/m^2{\cdot}d$ was considered as optimal. Three zeolite mixture were used to determine the optimal mixing ratio by volume of a zeolite(A) in the diameter range of 0.5 to 1mm to a zeolite(B) in the diameter range of 1 to 3mm diameter. 1 : 3, 1 : 1 and only B in A to B by volume were tested at hydraulic load $314L/m^2{\cdot}d$ and filtering hight 100cm. $COD_{cr}$ removal efficiency was more than 89% at mixing ratios of 1 : 3 and 1 : 1 in A to B. Removal efficiency was lower at the column filled with only B. Removal efficiency was better at filter medium filled with mixing ratio 1 : 1 in A to B than with the other mixing ratios. Thus, it was found that the mixture of mixing ratio 1 : 1 in A to B was appropriate for filter medium of constructed wetland. Removal efficiency was higher in down-flow than in up-flow, and $COD_{cr}$ and BOD were removed best in 20cm filter height near feeding area.

• 한국환경보건학회지
• /
• 제11권2호
• /
• pp.17-27
• /
• 1985

The objectives of this study is to examine efficiency of swinery wastewater treatment by trickling filters' pilot plant. The results of this study are as follows: 1. The characteristics of sample. The BOD$_5$ was from 2,450 to 2,880mg/l, COD(KMnO$_4$ acid method) was from 910 to 1,064mg/l, and SS was from 920 to 990mg/l. The pH of influent was from 7.3 to 7.6, and the temperature of water was from 17.0$\circ$C to 22.5$\circ$C. 2. For experiment by recirculation, the BODs removal efficiency is 65.2% at recirculation ratio (r)=0, and 70.7% at r=1. The ramoval efficiency of this study is higher than NRC formula of U.S.A.. The recirculation is not significant effect on removal efficiency. 3. For experiment by hydraulic load, the BOD$_5$ removal rate decreased from 73.1% at $3.1m^3/m^2\cdot d$ to 65.3% at $9.2m^3/m^2\cdot d$. The design formula of this study which shows the removal rate of soluble BOD is $Le/Li =10^{-0.24} D/Q^{0.24}$ (Q: hydraulic load, D: depth of filter). 4. For experiment by organic load, the BOD$_5$ removal rate is increased from 70.2% at $0.77kg/m^3\cdot d$ to 75.4% at $4.28kg/m^3\cdot d$. We can obtain the straight line y=0.749 x (y: removed BOD, x :applied BOD) by the least squares method. 5. We can know that trickling filters is strong with the hydraulic load and the organic matter shock load. Here, we can judge that trickling filters is a good method for the treatment of swinery wastewater which containing high concentrated organic matter.

• 한국산학기술학회논문지
• /
• 제20권2호
• /
• pp.741-749
• /
• 2019

굴삭기에 부착되는 유압 브레이커는 건물의 파괴 및 분해, 도로 포장재의 파손, 채석장에서의 암석 파단 등에 사용되고 있는 부착작업기의 일종의 건설 장비이다. 따라서 유압브레이커의 성능은 주로 충격량 및 충격 효율에 의해 평가되며, 이는 제조사 및 사용자 모두에게 중요한 요소이다. 본 논문에서는 건설 현장에서 주로 사용되는 20톤급 유압브레이커를 대상으로 상용 프로그램인 SimulationX를 사용하여 유압밸브 및 피스톤의 수압 면적 또는 작동 조건에 따라 유압 브레이커의 충격량 예측을 위한 모델링 및 해석을 진행하였다. 또한, 모델링 및 해석의 신뢰성을 확인하기 위하여 기존 실험 연구의 결과를 통하여 비교 및 검증하였다. 본 연구 결과는 제작 이전의 설계 단계에서 유압 브레이커의 충격량을 예측하고 충격량 향상을 위한 파라미터 연구에 도움이 될 것으로 본다. 또한 제조사 측에서는 본 논문의 결과를 통하여 유압 브레이커의 충격량을 미리 예측함으로서, 시행 착오 방지를 통하여 개발 시간 및 비용을 절감할 수 있을 것으로 예측한다.

• 한국안전학회지
• /
• 제33권4호
• /
• pp.119-126
• /
• 2018

In recent years, as flood damage caused by heavy rains increased, the great-depth tunnel using urban underground space is emerging as a countermeasure of urban inundation. The great-depth tunnel is used to reduce urban inundation by using the underground space. The drainage efficiency of great-depth tunnel depends on the intake design, which leads to increase discharge into the underground space. The spiral intake and the tangential intake are commonly used for the inlet facility. The spiral intake creates a vortex flow along the drop shaft and reduces an energy of the flow by the wall friction. In the tangential intake, flow simply falls down into the drop shaft, and the design is simple to construct compared to the spiral intake. In the case of the spiral intake, the water level at the drop shaft entrance is risen due to the chocking induced by the flowrate increase. The drainage efficiency of the tangential intake decreases because the flow is not sufficiently accelerated under low flow conditions. Therefore, to compensate disadvantages of the previously suggested intake design, the multi-stage intake was developed which can stably withdraw water even under a low flow rate below the design flow rate. The hydraulic characteristics in the multi-stage intake were analyzed by changing the flow rate to compare the drainage performance according to the intake design. From the measurements, the drainage efficiency was improved in both the low and high flow rate conditions when the multi-stage inlet was employed.