• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.255-263
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• 2005

Migration experiments of THO and 237Np have performed through a sampled granite core in Chemlab2 probe at the Aspo hard Rock laboratory. The elution curves of THO were analysed to determine hydraulic properties such as the extent of dispersion effect according to flow rates. The retardation phenomena of the solutes were observed and described with elution curves and migration plumes. After migration test, the rock core was opened, and the remaining radioactivities on the rock fracture surfaces were measured. The transport process was simulated with a two-dimensional channel model. The mass transport process was described with three types of basic processes ; advection, sorption and matrix diffusion. By the combination of these processes, effects of each process on transport were described in terms of elution curves and migration plumes. By comparing the simulation results to the experimental one, it was possible to analyse the retardation effect quantitatively.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1060-1067
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• 2009

Previous research on the slope failure has mainly reported that most of the slope failures occur due to surface rainfall infiltration in the rainy season. A slope of which surface is protected by shotcrete or plants, can also fail due to increase in pore water pressure from the ground water flow beneath the surface, rather than from the surface. In this study such case of slope behavior is investigated using the model test and numerical method including strength reduction method. Hydraulic boundary conditions of the slopes is considered using coupled numerical scheme. The failure mechanism of the slope is investigated and the effect of pore water pressure on slope safety is identified. Increase in pore water pressure due to lateral infiltration has significantly reduced the stability of slope.

• Nuclear Engineering and Technology
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• v.43 no.1
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• pp.45-62
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• 2011

The Korean nuclear industry is developing a thermal-hydraulic analysis code for safety analysis of pressurized water reactors (PWRs). The new code is called the Safety and Performance Analysis Code for Nuclear Power Plants (SPACE). The SPACE code adopts advanced physical modeling of two-phase flows, mainly two-fluid three-field models which comprise gas, continuous liquid, and droplet fields and has the capability to simulate 3D effects by the use of structured and/or nonstructured meshes. The programming language for the SPACE code is C++ for object-oriented code architecture. The SPACE code will replace outdated vendor supplied codes and will be used for the safety analysis of operating PWRs and the design of advanced reactors. This paper describes the overall features of the SPACE code and shows the code assessment results for several conceptual and separate effect test problems.

• Journal of Drive and Control
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• v.15 no.3
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• pp.36-42
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• 2018

Agricultural tractors require frequent shifting to improve operation efficiency, and PST (Powershift Transmission) is considered as a suitable transmission. However, due to the inherent characteristics of the PST, shocks arise during shifting, which imparts a negative effect on the operator. Therefore, in order to improve the transmission performance of the tractor PST, researches on various methods including the hydraulic system circuit, the engine input speed control, and the mechanical system of the transmission are steadily being conducted. In this study, in order to reduce the impact of PST on a shift based on SimulationX software, we analyzed the characteristics of the input signal of PCV (Pressure Control Valve) through sensitivity analysis and verified the simulation model through actual vehicle test. Optimization was performed for minimizing the shift shock for some of the parameters of the input signal at constant temperature and RPM conditions.

• Journal of Ocean Engineering and Technology
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• v.2 no.1
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• pp.163-169
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• 1988

A beach nourishment method can be used as one of the beach. The beach nourishment is affected br a natural condition and an artificial condition; a natural condtion include conditions of bottom slope, diameter of bottom materials and wave, and an artificial condition include deposit position, method, diameter and quantity of the nourishing sand. To obtain and the best diameter of the nourishing sand a two-dimensional hydraulic model test, which simulates the erosional beach, has been accmplished. In this study the protection of the beach erosion can be maximized when the nourishing sand of 0.84mm in diameter, which is about 2.5-3.5 times of the natural bottom materials in diameter.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.109-117
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• 2011

It was calculated using empirical formulas for the weight of Tetrapod, which was a representative armor unit in the rubble mound breakwater in Korea. As the formulas were evaluated from a curve-fitting with the result of hydraulic test, the uncertainty of experimental error was included. Therefore, the neural network and M5' model tree were used to minimize the uncertainty and predicted the stability number of armor block. The index of agreement between the predicted and measured stability number was calculated to assess the degree of uncertainty for each model. While the neural network with the highest index of agreement have an excellent prediction capability, a significant disadvantage exists that general designers can not easily handle the method. However, although M5' model tree has a lower prediction capability than the neural network, the model tree is easily used by the designers because it has a good prediction capability compared with the existing empirical formula and can be used to propose the formulas like an empirical formula.

• Journal of Aerospace System Engineering
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• v.16 no.2
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• pp.49-62
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• 2022

The purpose of this paper was to present a model analysis-based design process and verification results for the high-lift control system of aircraft. For this, we used Matlab/Simulink, one of the most widely-used physical modeling tools. The high-lift control system can be divided into three domains. (i.e., Electronic control domain, Hydraulic actuation domain, and Mechanical power transmission domain) Based on this division, we modeled each of the major domains and sub-components, and integrated them to complete the complicated system model. During the development process, each model block was tuned by referring to the results of pre-test and parts acceptance tests. As a result, the entire performance model and the developed system were completely verified, through unit components and system integrated performance tests. Finally, we summarize the process and results applied to the design process of high-lift control system and present future work.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.807-812
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• 2011

Fuel-side cold-flow tests were performed on the technology demonstration model of a 75 ton-class liquid rocket engine combustion chamber for the first stage of the Korea space launch vehicle II. Pressure drop in the cooling channels of the combustion chamber was measured by changing fuel mass flow rate through a pressure regulating system. Pressure drop in each segment of the chamber could be obtained and a lot of pressure drop was caused by high flow velocity in the nozzle throat segment. The accuracy of a hydraulic analysis method for calculating a pressure loss in cooling channels could be verified by applying it to the cold-flow test conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.56-61
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• 2012

Fuel-side cold-flow tests were performed on the technology demonstration model of a 75 ton-class liquid rocket engine combustion chamber for the first stage of the Korea space launch vehicle II. Pressure drop in the cooling channels of the combustion chamber was measured by changing fuel mass flow rate through a pressure regulating system. Pressure drop in each segment of the chamber could be obtained and a lot of pressure drop was caused by high flow velocity in the nozzle throat segment. The accuracy of a hydraulic analysis method for calculating a pressure loss in cooling channels could be verified by applying it to the cold-flow test conditions.

• Journal of Aerospace System Engineering
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• v.11 no.6
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• pp.84-91
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• 2017

The dynamic characteristics of a ducted fan in hovering condition were investigated. The section properties of the fan blade were calculated, and a simulation model was developed according to the rotor system components. Dynamic analyses were conducted relative to the rotational speed and the collective pitch. The proposed ducted fan system showed less aero-elastic instability within the designated operating ranges. To verify the analytical approach, a rotating test stand of the ducted fan was set up. A functional test of the assembly was carried out to determine the kinematics and interference between components. The non-rotating and rotating normal frequencies were measured by excitation of the collective pitch using hydraulic actuators. The results indicated a correlation between the test equipment and the simulation model.