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.

Abstract
 1. 서론
 2. 설계 및 전산해석
  2.1 설계이론
  2.2 전산해석
 3. 실험방법 및 결과
  3.1 실험장치 및 방법
  3.2 실험결과 및 분석
 4. 결론
 References

• 이경훈(Graduate School of Wonkwang University) | Kyoung-Hun Lee
• 김병삼(Wonkwang University Dept. of Mechnical & Automotive Engineering) | Byoung-Sam Kim Corresponding Author
• 김형두(Wonkwang University, Department of Fire Service Administration) | Hyung-Doo Kim