Internal combustion engine is the main source of environmental pollutants and therefore advanced technology is required to reduce harmful elements from the exhaust gases all over the world. Especially, when the exhaust gas is released from the automotive muffler, exhaust noise has many bad influence on the surrounding environment. In order to reduce the exhaust noise, it is necessary that automotive muffler must be designed for best exhaust efficiency. The sound insulation room was installed for the analysis of an acoustics characteristics of the noise from automotive muffler, in this study. Exhaust gas noise, noise distribution characteristics, pressure and temperature of exhaust gas were investigated with the change of annulus temperature of air cooled annulus automotive muffler and cooled annulus automotive muffler. The following results were obtained with this study. From the frequency analysis of automotive muffler, high noise distribution was observed in the range 100~2000Hz. It means that the noise in this range has an dominate influence for the overall noise. Noise reduction of automotive muffler was affected by the temperature of annulus. It is caused the result that the high temperature and pressure of exhaust gas are changed lower by the drop of annulus temperature. The tendencies of noise, the temperature and pressure of exhaust gas are similar to the performance curve of engine. Exhaust gas pressure is determined by the r.p.m. of engine and affected by the cooling performance of automotive muffler.

Refrigerators used in homes occupy a large portion of the power consumption. In addition, most of the power consumption of the refrigerator is used by the compressor. Therefore, it is necessary to study on the improvement of compressor efficiency to save energy. In this study, the suction system was changed to improve the efficiency of the linear compressor. For this, numerical analysis was performed by linking the 1 dimensional lumped model and the 2 dimensional axisymmetric CFD model. The numerical analysis results were also compared with the experimental results. As a result of the numerical analysis, the model with modified suction system increased EER by about 0.25% compared to the basic model, which was also confirmed by experiment.

The tyre/road noise becomes aggravated due to the rapid increase of motor vehicles. It has a great effect on the dwelling environment. Therefore we investigate the characteristics and sources of the tyre/road noise through grasping the status of the tyre/road noise. Traffic noise results from the collective contribution of the noise produced by individual motor vehicles. The tyre/road noise varies enormously depending upon its type and mode of operation. In this study, we investigate the noise labelling of EU tire.

The noise from the exhaust system to the engine is important in terms of the problem of noise pollution, as well as improved marketability, there are many studies being made. Normally, the exhaust noise change is the exhaust manifold of the muffler or four days depending on the structure of the portion of the shape and the Lancer, called look a big difference, and the perforated pipe resonance, expression that contains a study of the structure of the muffler is a general precedent. This muffler is based on four wheel to differentiate between the borrower and the borrower can be broken down into a motorcycle. The details of the stock muffler, the muffler is tuned racing use. Therefore, this study is the last motorcycle noise and exhaust emission for environmental tests have not been established yet 125cc motor cycle noise is used as a reference for the criteria for information about the experiment. There are few types of motorcycle muffler, such as stock muffler, slip on muffler and full system muffler used racing. On this study through to the measurement motorcycle exhaust noise and analysis 1/3 octave band get a target frequency. For the design resonance muffler used Helemholtz’s resonance formular. Also when design the muffler consider mount of frame. This studied expect reduction noise without sound absorption.