• International Journal of Safety
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• v.5 no.1
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• pp.17-23
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• 2006

An investigation was carried out to determine the effect of the thickness of the air-gap installed between the roof metal sheet and the headliner on booming noise in passenger cars. In addition, a way of offering quieter driving condition to drivers and passengers was studied. It was found that a very thin air-gap corresponding to approximately 3/100 of the height of the passenger compartment causes noticeable change in the coupled resonance frequencies and acoustic responses. Furthermore, a guideline is proposed for determining an optimal air-gap thickness during design stage of the air-gap beneath the roof metal sheet for reducing booming noise.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.2
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• pp.111-118
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• 2004

A number of researchers have attempted to measure the reverberation time of a passenger car, ut the reverberation time of passenger car is too short to measure with the traditional band pass filter. And if the reverberation time is very short, the product of the reverberation time (T) and the bandwidth (B) of the traditional band pass fitter becomes small. The low limit of BT product required for the measurement of reverberation time with the traditional band pass filter is 16. In order to overcome this problem, the wavelet filter bank was developed. In this study, this new wavelet filter was employed to measure the reverberation times of five different classes of passenger cars. The low limit of BT product required for the measurement of reverberation time with the wavelet filter is 4. The reverberation times of five passenger cars were measured successfully with the new wavelet filter bank. The reverberation times measured in most passenger cars was found to be around 0.04. Compared with general acoustic rooms like concert halls, this is a very short reverberation time

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1577-1584
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• 2002

This paper develops a finite element model for studying the occupant behavior and injury cofficients of a large-sized cab-over type truck. Since it does not have a room to absorb collision energy and deformation in front of the passenger compartment the deformation is directly transmitted to the passenger compartment. Moreover, since its steering column is attached on the frame, severe deformation of the frame directly affects on the steering wheel's movement. Therefore, if the occupant behavior and injury coefficients analysis is performed using a finite element model developed based on a sled test, it is very difficult to expect acquiring satisfactory results. Thus, the finite element model developing in this paper is based on the frontal crash test in order to overcome the inherent problems of the sled test based model commonly used in the passenger car. The occupant behavior and injury coefficients analysis is performed using PAM-CRASH installed in super-computer SP2. In order to validate the reliability of the developed finite element model, a frontal crash test is carried out according to a test method used fur developing truck occupant's secondary safety system in european community and japan. That is, test vehicle's collision direction is vertical to the rigid barrier and collision velocity is 45kph. Thus, measured vehicle pulses at the lower parts of the left and right B-pilla., dummy chest and head deceleration profiles, HIC(head injury criterial) and CA(chest acceleration) values, and dummy behavior from the frontal crash test are compared to the analysis results to validate reliability of the developed model.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.4 s.148
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• pp.451-459
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• 2006

When a ship is damaged and flooded, the motion of the damaged ship is significantly influenced by the flooding water dynamics. The flooding water in the damaged ship has been treated as a lumped mass under the quasi-static assumption in most of previous researches. To calculate the motion of damaged ship rigorously, it is necessary to analyze the coupled dynamics of flooding water. In this study, a series of numerical and experimental studies is conducted for the damaged part of ITTC RORO passenger. FLOW3D is used for investigating the feasibility of the state of the art CFD technique. An applicability of the coupled motion analysis of damaged ships can be confirmed by agreement between the numerical results and the model experiments. A CFD technique is considered for the numerical modeling of the dynamics of flooding water.

• Journal of Ocean Engineering and Technology
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• v.20 no.3 s.70
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• pp.24-36
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• 2006

This paper investigates wave loads of ships that suffer sinkage due to flood in a compartment caused by damage on the side of the hull. By analyzing ships with various sizesof damage opening, the influence of opening size on ship response is investigated. The motion of the damaged ship is analyzed by using the boundary element method, based on three-dimensional potential theory, considering hydrodynamic pressure in the flooded compartments. The shear forces, bending moments and torsional moments are calculated by the direct integration of the three dimensional hydrodynamic pressure on the outer and inner hulls. A RORO passenger ship with length of 174.8 m is considered in the numerical example, and results for wave loads are discussed.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.2
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• pp.15-20
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• 1983

The nature and the sources of sound in cars is discussed in the light of many previous works, and the importance of the system resonances inside cars is suggested. An investigation of a 'boom' problem in a small size passenger car is described. It was established that the 'boom' frequencies coincided with engine firing frequency and also with several system resonances. To find out main transmission path of the noise to the car interior, various possible sources were eliminated from the investigation by means of simple modification to the vehicle. Data on the structural modes of the body, and the acoustic modes of the passenger compartment at various forcing cases were obtained to provide better understanding of the problem. It was found that the acoustic resonance responsible for the boom was controlled largely the bending motion of the floor. To investigate the effect of the structural modification to the acoustic response, center floor of the car was reinforced. a great reduction of the noise inside the car especially at the offending speed range, was achieved by this modification.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.583-588
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• 2004

Opening commercial service of KTX at the time of demanding more flexible train set for HONAM line and JEONLA line, it's necessary for the Korean High speed train, performing the stabilization; to modify the design in aspect of passenger and maintenance. In order to ensure the optimized interior design in Korean High speed train, it is necessary to review the major items such as disabled passenger facility, toilet, seat arrangement, compartment partition and door, access door, electrical cabinet, color and paint through the European standard and compare with other high speed train.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.198-204
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• 2001

Train crashes involve complex interaction between deformable bodies in multiple collisions. The purpose of this study is to suggest the effective analytical procedure using hybrid model for the crashworthiness of motorized trailer of high speed train. The hybrid approach, with very short modeling times and reduced computation times to extract the global behaviour and to perform a pre-optimization of the considered structure. Firstly, various types of crash events are investigated and the conditions for numerical simulation are defined. In this paper, the structural crashwonhiness of Korean High Speed Train trailer was examined through FE analysis. Crash analyses on energy absorbing part and safety zone were carried out to determine each section force. Rollover analysis was performed to observe the amount of intrusion in the passenger's area in case of rollover accident.

• Journal of KSNVE
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• v.9 no.1
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• pp.97-102
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• 1999

Structure-borne noise is an important aspect to consider during the design and development of a vehicle. In this work. it was desired to identify the primary paths associated with structure-borne noise generated from the engine and front suspension. An experimental source-path-receiver model was used to characterize the system. A variety of primary sources such as engine. tires or exhaust system generate vibrations of the inner surfaces of the passenger compartment of a vehicle which subsequently radiate noise. The source was characterized by the force acting at the engine-to-body interface. and the path was characterized by pressure over force FRF's. The excitation forces were indirectly determined using dynamic stiffness of rubber mount or the system accelerance matrix. Through these analysis, path contribution diagram which is well expressed primary noise path is obtained.

• Journal of KSNVE
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• v.10 no.5
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• pp.806-810
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• 2000

This paper presents a practical method for reduction of interior noise and improvement of sound quality in compartment of passenger car. The tested vehicle has a booming noise problem at rear passenger seats. In order to identify the transfer path of interior noise, the running modal analysis, the vibro-acoustic frequency transfer response and the noise path analysis are systematically employed. Using these various methods, it has been founded that the rear part of the roof of the test car was a noise source for the booming noise. Through the modification of the roof, the booming noise has been reduced and sound quality inside car also has been improved.