PartI of this paper identified the location and size of the noise sources from the axial flow fans, and partII based on that, identified the magnitude of sound pressure from the case and the blade according to frequency in the range of 2200 Hz to 5000 Hz. The equation of Lighthill was used for calculation. Generally, when measuring noise, the analytical area was extended more than 1m from the outlet of the fan. To eliminate the effects of backflow coming from the rear of the fan, the analytical area was extended a little longer than 1m. From the results of the analysis, high noise occurs in the low frequency area, and the lower noise becomes in the high frequency area. The maximum sound pressure generated in the range of 2000Hz~5000Hz is 65dB at a distance of 1m and 82dB at the outlet of the fan. Noise of the fan mainly occurred around the blade and guide, and the noise decreased as the frequency increased between 2200Hz and 3400Hz, but the noise increased as the frequency increased between 3800Hz and 5000Hz.

ABSTRACT
 1. 서 론
 2. 수치해석 방법
  2.1 수치해석 방법 및 해석 이론
  2.2 수치해석 대상 및 격자
  2.3 해석 및 경계 조건
 3. 수치해석 결과
  3.1 팬 내부 압력분포
  3.2 팬에서 발생하는 소음의 위치와 크기
 4. 결 론
 후 기
 References

• 남현택(Jeonbuk National University, Dept. of Mechanical Eng.) | Hyeontaek Nam
• 전유선(Jeonbuk National University, Dept. of Mechanical Eng.) | Yuseon Jeon
• 김진택(Jeonbuk National University, School of Mechanical System Eng.) | Jintaek Kim
• 이철형(Dae Ryun Industrial Company) | Cheolhyung Lee
• 선광명(Dae Ryun Industrial Company) | Kwangmyung Sun
• 이승로(Jeonbuk National University, Dept. of Mechanical Eng.) | Seungro Lee Corresponding Author