• Journal of KSNVE
• /
• v.8 no.6
• /
• pp.1062-1068
• /
• 1998

This paper describes the vibration characteristics of a high head pump-turbine runner. with nine blades and an outer diameter of 4.410 mm. of the pumped storage power plant. Mode shapes and natural frequencies were obtained by means of both the finite element analysis and modal testing. both in air and in water. The natural frequencies in air were calculated using the finite element method by ANSYS software. In order to confirm calculation results. the natural frequencies and mode shapes of the runner were measured using a hydraulic exciter both in air and in water. Natural frequencies of the pump-turbine runner were found at 174. 310 Hz in air, and at 107. 184 Hz in water. The first mode shape is flat plate mode with two nodal diameter and the second one is also flat plate mode with three nodal diameter. It can be shown that the natural frequencies of the pump-turbine runner in water is reduced approximately 40 ％ due to additional mass effect. Natural frequencies in air predicted by ANSYS software are in good agreement with test results.

• 유체기계공업학회:학술대회논문집
• /
• 2001.11a
• /
• pp.171-176
• /
• 2001

The Pump/Motor Selection Program for optimized selection of regional water supply facilities was developed based on a flowchart compiled from basic operational data, total head requirement, initial pump/motor specification selection etc.. This program was developed in Visual Basic. The program accepts, as in the flowchart, operational requirements of pumps and other system requirements and calculates specific speed based on flow rate, total head and na Then the calculated specific speed is used to select pump types and rpm Prior to determining likelihood of cavitation occurring at the calculated NPSH. Power requirement is then calculated for safe operation of pump to assist final pump selection. Test results of the program matches very closely to the design values of Paldang intake pump station(3rd stage) proving that the program can be used as an effective and practical aid for designing new regional water supply systems.

• Journal of the Society of Naval Architects of Korea
• /
• v.45 no.1
• /
• pp.101-107
• /
• 2008

According to the existing research result on the seabed organic sediment, pollutants from the land and the sea contaminate the coastal water and sediment on the seabed. To tackle this problem, we need to dredge organic sediment. In the present paper, the development of removing system of seabed sediment by the difference of water head is researched by experimental method. For the validation of the decompression system, computations for validation are carried out for sediment removing equipment. The performance of inhalation equipment is analysed by some model tests.

• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.49-53
• /
• 2004

LabVIEW is mostly preferred to use in experiment, measurement and control as one of the useful thing in America and Europe. So, We tried performance experiment of a single-stage closed-type centrifugal pump by using the LabVIEW. The pump rpm and the shaft torque are measured by rpm sensor and torque sensor The test pump's maximum rpm, head, kW are 1,750, 13m, and 1.5kW, respectively The casing is made up with transparency acrylic for confirmation the flow patterns. We installed experimental equipment for air water two phase flow. This paper tries to analyze the single-phase flow characteristics through this air water two phase flow experimental apparatus. The performance results of a single-stage closed-type centrifugal pump satisfied reappearance and coincide well with head and coefficients according to the change of rpm.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.48 no.1
• /
• pp.81-88
• /
• 2006

Numerical analyses were carried out for studying on seepage problems due to seawater intrusion through the embedded rock layers of the sea-dike. A seepage analysis model, SAMTLE was developed fur two-layer embankment system. The analyses by SAMTLE showed that the size of embedded rock layer had a significant effect on the seepage problems of sea-dike. If the embedded rock layer is longer and thicker, the seepage problems become more serious to water head, seepage rate and safety factor of piping in embankment. On the other hand, if the width of embedded rock layer is equivalent to the sea-dike's bottom width, the water head becomes lower and seepage rate and safety factor of piping are dramatically increasing. This makes another seepage problems such that the fresh water becomes saltier and higher seepage rates result in internal erosion of sea-dike.

• Nuclear Engineering and Technology
• /
• v.51 no.4
• /
• pp.1060-1068
• /
• 2019

This work aims to establish a model of a primary water stress corrosion crack growth rate of Alloy 690 material for the head penetration nozzles of Korean pressurized water reactors. The test material had an inhomogeneous microstructure with bands of fine-grains and intragranular carbides in the matrix of coarse-grains, which was similar to the archive materials of the head penetration nozzles. The crack growth rate was measured from the strain-hardened materials as a function of the stress intensity factor in simulated primary water at various temperatures and dissolved hydrogen contents. The effects of strain-hardening, temperature, and dissolved hydrogen on the crack growth rate were analyzed independently, and were then introduced as normalizing factors in the crack growth rate model. The crack growth rate model proposed in this work provides a key element of the tools needed to assess the progress of a stress corrosion crack when detected in thick-wall Alloy 690 components in Korean reactors.

• Journal of Korean Society of Water and Wastewater
• /
• v.36 no.4
• /
• pp.219-228
• /
• 2022

In this study, we propose a flow velocity evaluation scheme based on pressure measurement in pressurized pipeline systems. Conservation of mass and momentum equations can be decomposed into mean and perturbation of pressure head and flowrate, which provide the pressure head and flowrate relationship between upstream and donwstream point in pressurized pipeline system. The inverse impedance formulations were derived to address measured pressure at downstream to evaluation of flow velocity or pressure at any point of system. The convolution of response function to pressure head in downstream valve provides the flow velocity response in any point of the simple pipeline system. Simulation comparison between traditional method of characteristics and the proposed method provide good agreements between two distinct approaches.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2254-2256
• /
• 2004

Korea Water Resources Corporation (KOWACO), the only organization specialized in water resources management in Korea, is planning to establish a centralized control system for a related operation. in the central control room, of decision making as to water management and electric power generation. This plan is intended to convert the existing on-site operation system in each multi-purpose dam across the nation into a central operation system in the Corporations head office, for which Generation Integrated Operating System (GIOS) will be established control center in the Corporations head office and modernized nine (9) power stations. substations (RDAC). This article discusses realization of GTOS, especially real-time operation of hydropower plants and a specific architectural features for system communication.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.159-159
• /
• 2019

In this study, the simulation of sediment deposition at Sangju weir reservoir, South Korea, was carried out using artificial neural networks. The ANNs have typically been used in water resources engineering problems for their robustness and high degree of accuracy. Three basic variables namely turbid water inflow, outflow, and water stage have been used as input variables. It was found that ANNs were able to establish valid relationship between input variables and target variable of sedimentation. The R value was 0.9806, 0.9091, and 0.8758 for training, validation, and testing phase respectively. Comparative analysis was also performed to find optimum structure of ANN for sediment deposition prediction. 3-14-1 network architecture using BR algorithm outperformed all other combinations. It was concluded that ANN possess mapping capabilities for complex, non-linear phenomenon of reservoir sedimentation.

• Journal of the Korea Concrete Institute
• /
• v.29 no.3
• /
• pp.267-273
• /
• 2017

Recently, the researches of self-healing concrete technology are being carried out actively due to the advent of importance for the maintenance of concrete structures. A water permeability test has been widely used for the evaluation of self-healing performance. However, it is difficult to compare tests results since there is no standard test method related to the self-healing. A standard method for measuring the crack width does not exist neither though the self-healing performance is significantly influenced by the initial crack width. In this study, the effect of water head and crack width on water flow was investigated using a constant water head permeability test equipment. The correlation equation between the initial crack width and water flow was suggested through the regression analysis of test data, and the predicted crack widths agree well with the real crack widths measured using microscopy.