• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1147-1152
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• 2010

The wet brakes used in an industrial forklift often produce noise on braking. Elimination or reduction of this squeal noise is an important task for the improvement of comforts. In this paper, a test rig was developed which was possible for testing of brake noise and an experimental measurement on squeal noise was performed. The causes of the brake noise are identified by experimenting how the factors such as automatic transmission fluid, the groove of friction-plate pad and the material of friction-plate pad affect the squeal noise. In order to identify the squeal characteristics, the signal analyses for noise are performed by using frequency spectrums. Experimental results showed that the viscosity of automatic transmission fluid and the groove pattern of friction-plate pad largely affect the reduction of the wet brake squeal noise in an industrial forklift.

• Journal of ILASS-Korea
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• v.15 no.1
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• pp.38-43
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• 2010

The LPG(Liquefied Petroleum Gas) fuel attracts attention as a clean alternative fuel. In order to further reduce the exhaust emission and improve performance in LPG engines, the LPLi(Liquid Phase LPG Injection) system is used. In LPLi system, the fuel pump performance is important for keeping the LPG over it's saturated vapor pressure. An external fuel pump is needed to improve the durability for LPG engines. This paper predicted the variation of fuel properties on the LPLi system with an external fuel pump. From each component's thermodynamic model, an 1-D simulation is developed for LPLi system with an external fuel pump. Then the 1-D simulation data analyzed and compared with the rig-test. The 1-D simulation and the rig-test produced similar results.

• Journal of Power Electronics
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• v.14 no.5
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• pp.1069-1078
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• 2014

This study presents the design and implementation of a web-based remote laboratory for a multi-mode single-leg power converter, which is a topic in advanced power electronics course. The proposed laboratory includes an experimental test rig with a multi-mode single-leg power converter and its driver circuits, a measurement board, a control platform, and a LabVIEW-based user interface program that is operated in the server computer. Given that the proposed web-based remote laboratory is based on client/server architecture, the experimental test rig can be controlled by a client computer with Internet connection and a standard web browser. Although the multi-mode single-leg power converter can work at four different modes (main boost, buck-boost, boost-boost, and battery boost modes), only the buck-boost mode is used in the experiment because of page limit. Users can choose the control structure, control parameters, and reference values, as well as obtain graphical results from the user interface software. Consequently, the feedbacks received from students who conducted remote laboratory studies indicate that the proposed laboratory is a useful tool for both remote and traditional education.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.240-244
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• 2017

Experimental verification in the rig test stage for component development is a vital link between the aeromechanical design and structural integrity validation process. Based on this premise, Non-Intrusive Stress Measuring System was adopted on the axial compressor test rig to measure the static and dynamic tip deflection of all blades by using tip-timing sensors. Through analyzing vibration characteristics, we evaluated the vibratory stresses seen on the blades fatigue critical location; detected synchronous resonances which are the source of High Cycle Fatigue (HCF) in blades; presented non-synchronous vibration response by aerodynamic excitation and individual blade mis-tuning patterns.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.5
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• pp.650-658
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• 1997

Analysis and control of intake charge motion such as swirl and tumble are very important factors in improving the gasoline engine performance. In this paper, single-frame PTV (particle tracking velocimetry) is used to investigate intake tumble patterns in a steady flow test rig of gasoline engine with dual-intake-valve and pent-roof combustion chamber. Intake tumble pattern is quantified in accordance with blockage ratio of TIV (tumble intensifying valve) with single- frame PTv.The view of the instantaneous 2-D velocity field gives a realistic understanding of in-cylinder flow field. Thus it is confirmed that PTV is a effective tool in engine design. In conventional port, two tumble structures appear clearly, and the larger one is observed under the exhaust valve side and the smaller is right below the intake valve side. The larger vorticity is observed in TIV port, thus it is concluded that TIV have an effect on intensified tumble motion in cylinder flow.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.136-142
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• 2008

The influence of different grids on numerical prediction of subsonic compressor performance and stall was investigated. Two types of grids were examined, structured H type grid and structured O-H type grid. Evaluations were conducted by comparing the numerical results with experimental results obtained from a low-speed single-stage rig test for a new concept compressor, called diffuser passage compressor, aiming at improving tip clearance sensitivity. At low mass flow operating conditions, the numerical calculation with O-H type grid showed that the lowest mass flow operating point for which the calculation was able to converge was almost the same as the lowest steady mass flow obtained from the rig test. On the other hand, the numerical calculation with structured H type grid diverged at higher mass flow operating point. It was found that this difference was attributed to the effect of double-valuedness of H type grid that existed at leading edge on the boundary layer development on the blade surface.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.12
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• pp.807-814
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• 2015

A control rod drive mechanism(CRDM) is a reactor regulating system, which inserts, withdraws or maintains a control rod containing a neutron absorbing material within a reactor core to control the reactivity of the core. The top-mounted CRDM for Jordan Research and Training Reactor(JRTR) with 5 MW power has been designed and fabricated based on the HANARO's experience through KAERI and DAEWOO consortium project. This paper describes the performance qualification test results to demonstrate the operability of a prototype and four production CRDMs during the reactor lifetime. The driving performance, the drop performance and the endurance tests for CRDM are carried out at a test rig simulating the actual reactor conditions. A vibration of internal components due to the coolant flow is also measured using a laser vibrometer. As a result, the CRDMs are driven having a good driving performance without a malfunction between command and output signals for the stepping motor. Also, the pure drop time and the impact acceleration are within 0.72 s and 4.2 g to meet the design requirements, and the vibrational displacement of control rod is measured as maximum $5.2{\mu}m$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.223-229
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• 2016

In this study, a cold forging process was developed for the roller tappet housing of an engine valvetrain system. A tappet sample was manufactured and subjected to an endurance test. The material properties were obtained from a compression test, and forging analysis was carried out to design a forging process using a commercial program, Deform-3D. The forging process was set up based on the analysis results, and a die set and sample tappet housing were manufactured. To evaluate the sample, the dimensional accuracy, surface roughness, parallelism, and concentricity were measured and confirmed. To evaluate the actuation and durability, a special test rig was developed to simulate the valvetrain system of the engine. An actuation test was performed based on the idle speed of a general diesel engine, and an endurance test was done based on the maximum speed. The results show minor wear of 0.002 mm. The developed test rig will be used to evaluate the actuation and durability of other valvetrain parts.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.354-359
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• 2001

A flexible rotor was smoothly passed through its bending critical speed, which is supported by AFB. Then, maximum magnitude of the rotor vibration at the middle point was 25${\mu}$m. The test rig was largely consisted of air turbine, multi-leaf type air foil bearing and flexible rotor and its bending critical speed was 32,600 rpm. And the balancing system and method for field balancing of the flexible rotor were developd successfully.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.30-37
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• 1998

It is well known that reduction of friction loss due to the valve train system greatly affects on improvement of fuel economy in internal combustion engine. In order to investigate friction characteristics of valve train system we carried out friction force measurement using test rig developed by ourselves. From test results, we concluded that characteristics of lubrication and friction torque on the valve train system such as mixed and hydrodynamic was mainly governed the contact type between cam and tappet.