• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.858-863
• /
• 2001

In this paper, the test and result of flow and combustion for 21AFR lean fuel models are described. The necessity to develop the low emission combustor has been issued from the concern on the increase of green house and the destruction of ozone layer. To evaluate the flow and combustion performance of new designed 21AFR lean modules, the hydraulic tests in stereo lithographic airflows models, the low pressure combustion tests in three injectors model for weak extinction and ignition and the high pressure combustion tests in single sector for NOx, SAE and efficiency are performed. The low pressure tests reveal that the governing parameters in weak extinction and ignition at atmospheric condition are prefilmer length, swirl flow rotation direction, secondary swirl angle and flow split. As a results of combustion test at high pressure, the efficiency and smoke level are satisfied with performance targets, but EINOx of 17.8 is higher than target value of 13.1. The high pressure tests show that the main parameters influenced on NOx are primary swirl angle, swirl flow rotation direction, heatshield exit angle and liner mixing hole location.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.8
• /
• pp.1132-1137
• /
• 2002

In this paper, the test results of the combustion for 2 IAFR lean fuel models are described. The need for the low emission combustor has been issued from the concern on the increase of green house and the destruction of ozone layer. To evaluate the flow and combustion performance of newly designed 21AFR lean modules, the hydraulic tests in stereolithographic airflows models, the low pressure combustion tests in three injectors model for weak extinction and ignition and the high pressure combustion tests in single sector for NOx, SAE and efficiency are performed. The low pressure tests reveal that the governing parameters in weak extinction and ignition at atmospheric condition are prefilmer length, swirl flow rotation direction, secondary swirl angle and flow split. As a result of combustion test at high pressure, the efficiency and smoke level are satisfied with performance targets, but EINOx of 17.8 is higher than target value of 13.1 The high pressure tests show that the main parameters influenced on NOx are primary swirl angle, swirl flow rotation direction, heatshield exit angle and liner mixing hole location.

• Aerospace Engineering and Technology
• /
• v.8 no.1
• /
• pp.26-31
• /
• 2009

Three Lox pumps and one fuel pump are manufactured for turbopump real-propellent tests and water tests of the pumps are performed in order to estimate the performance characteristics of the pumps. According to the test results, the test region(flow ratio, cavitation number) of the pumps at the water tests cover the operating region at the real-propellent tests and also all the pumps satisfy the design requirement. The head of the Lox pumps shows a 2% difference among them due to the internal geometry, but the efficiency and overall cavitation performance are almost same. It is found that the fuel pump has a similar head and efficiency compared with the previous model of the same internal geometry, while it has a little inferior cavitation performance.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.7
• /
• pp.1401-1407
• /
• 2002

This paper represents an investigation of the vehicle-to-vehicle distance control system using Hardware-in-the-Loop Simulation(HiLS). Control logic is primarily developed and tested with a specially equipped test vehicle. Establishment of an efficient and low cost development tool is a very important issue, and test vehicle approach is costly and time consuming. HiLS method is useful in the investigation of driver assistance and active safety systems. The HiLS system consists of a stepper motor for throttle control, a hydraulic brake system with an electronic vacuum booster, an electronic controller unit, a data logging computer which are used to save vehicle states and signals of actuator through a CAN and a simulation computer using mathematical vehicle model. Adaptation of a CAN instead of RS-232 Serial Interface for communication is a trend in the automotive industry. Since this environment is the same as a test vehicle, a control logic verified in laboratory can be easily transferred to a test vehicle.

• Proceedings of the KIEE Conference
• /
• 1996.11a
• /
• pp.317-319
• /
• 1996

In this paper, an active vibration control system using a voice coil type linear oscillating actuator(LOA) is studied to suppress structural vibration. Being compared with a hydraulic actuator, a LOA has simplified structure and requires a few elements in the driving system, so it has lots of merits with respect to economics and maintenance. The general mathematical dynamic model to obtain the algorithm for the realization of vibration active control system is treated. Actually, the performance test of the control system using LOA is carried out on a steel test structure under sinusoidal and white noise excitation. From this test it is conformed that acceleration level of test structure is reduced near the resonance region. In the future research on the application to large structures will be studied.

• International Journal of Fluid Machinery and Systems
• /
• v.8 no.4
• /
• pp.264-273
• /
• 2015

This presentation describes an experimental approach for the detection of cavitation in hydraulic machines by use of ultrasonic signal analysis. Instead of using the high frequency pulses (typically 1MHz) only for transit time measurement different other signal characteristics are extracted from the individual signals and its correlation function with reference signals in order to gain knowledge of the water conditions. As the pulse repetition rate is high (typically 100Hz), statistical parameters can be extracted of the signals. The idea is to find patterns in the parameters by a classifier that can distinguish between the different water states. This classification scheme has been applied to different cavitation sections: a sphere in a water flow in circular tube at the HSLU in Lucerne, a NACA profile in a cavitation tunnel and two Francis model test turbines all at LMH in Lausanne. From the signal raw data several statistical parameters in the time and frequency domain as well as from the correlation function with reference signals have been determined. As classifiers two methods were used: neural feed forward networks and decision trees. For both classification methods realizations with lowest complexity as possible are of special interest. It is shown that two to three signal characteristics, two from the signal itself and one from the correlation function are in many cases sufficient for the detection capability. The final goal is to combine these results with operating point, vibration, acoustic emission and dynamic pressure information such that a distinction between dangerous and not dangerous cavitation is possible.

• Journal of Korea Water Resources Association
• /
• v.31 no.3
• /
• pp.347-360
• /
• 1998

Numerical simulations for fluid flow and solute transport in a fracture rock masses are performed by using a transient flow model, which is based on the three-dimensional stochastic and discrete fracture network model (DFN model) and is coupled hydraulic model with mechanical model. In the numerical simulations of the solute transport, we used to the particle following algorithm which is similar to an advective biased random walk. The purpose of this study is to predict the response of the tracer test between two deep bore holes (GPK1 and GPK2) implanted at Soultz sous Foret in France, in the context of the geothermal researches.l The data sets used are obtained from in situcirculating experiments during 1995. As the result of the transport simulation, the mean transit time for the non reactive particles is about 5 days between two bore holes.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.3
• /
• pp.575-592
• /
• 2018

Tunnelling is getting more important solutions for problems induced by the growth population in urban areas. Many studies on tunnelling below existing structure are carried out by many researchers. In general, however, ground water condition is ignored for most of researches using laboratory model test, so far. In case of ground behavior, error can occur if the result of effective stress related to hydraulic condition can't be taken into considerations. In this study, therefore, laboratory model test and the close range photogrammetry were conducted to investigate behaviour of ground and shallow foundation using newly device drainage system which is available to express the ground water condition. Also, numerical analysis was carried out to compare to results from the laboratory model test, and was performed with two methods, one is plastic and the other one is fully coupled analysis. Results from those two methods were compared to that of the laboratory model test.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.2 s.75
• /
• pp.35-41
• /
• 2007

In general, coastal damage is mostly occurred by the action of complex factors, like severe water waves. If the maximum storm surge height combines with high tide, severe water waves will overflow coastal structures. Consequently, it can be the cause of lost lives and severe property damage. In this study, using the numerical model, the storm surge was simulated to examine its fluctuation characteristics at the coast in front of Noksan industrial complex, Korea. Moreover, the shallow water wave is estimated by applying wind field, design water level considering storm surge height for typhoon Maemi to SWAN model. Under the condition of shallow water wave, obtained by the SWAN model, the wave overtopping rate for the dike in front of Noksan industrial complex is calculated a hydraulic model test. Finally, based on the calculated wave-overtopping rate, the inundation regime for Noksan industrial complex was predicted. And, numerically predicted inundation regimes and depths are compared with results in a field survey, and the results agree fairly well. Therefore, the inundation modelthis study is a useful tool for predicting inundation regime, due to the coastal flood of severe water wave.

• Journal of Ocean Engineering and Technology
• /
• v.10 no.4
• /
• pp.149-159
• /
• 1996

Multipurpose development of the coast and ocean can be considered as multifunction construction combining the functions of coastal protection, waterfront amenity and creation or rehabilitation of habitats. Multfunction development of coastal and ocean spaces can be accomplished by applying the ecosystem control structure of artificial habitats which will cultivate fishing ground with ecological harmony to the coastal protection system. To evaluate the applicability of ecosystem control structures as as fundamental coastal protection structure, wave control function of the structure is studied by numerical and physical analyses. Dimensional analysis and hydraulic experiment point out the importance of width and crest depth of ecosystem control structure, construction water depth and wave steepness. Wave control efficiency is estimated by the attenuation coefficient $(K_H)$ according to wave steepness $(H_0/L_0)$, relative constructed water depth $(h_i/H_0)$, relative berm width $(B/L_0)$ and relative crest depth $(h_B/H_0)$ of eosystem control structure. Empirical fomulas are suggested based on the results of model test by applying the multiple model based on this experimental results and numerical wave shoaling-dissipation-breaking model appears to be valid for the analysis of wave transformation around ecosystem control structure in the coastal waters.