Journal of Navigation and Port Research (한국항해항만학회지)

Korean Institute of Navigation and Port Research (한국항해항만학회)
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Higher Order Spectral Analysis of Non-linear Pitching Motion

고차스펙트럼을 이용한 선체 종동요의 비선형적 거동에 관한 해석

  • Kang, Byung-Ho (Underwater Vehicle Research Center, Korea Maritime and Ocean University) ;
  • Carlos, Miguel Mejia (Graduate course of Navigation Science, Korea Maritime and Ocean University) ;
  • Kim, Tae-Ho (Graduate course of Navigation Science, Korea Maritime and Ocean University) ;
  • Park, Jun-Mo (Sea Training Center, Korea Maritime and Ocean University) ;
  • Kong, Gil-Young (Division of Navigation Science, Korea Maritime and Ocean University)
  • 강병호 (한국해양대학교 수중운동체특화 연구센터) ;
  • ;
  • 김태호 (한국해양대학교 항해학부 대학원) ;
  • 박준모 (한국해양대학교 운항훈련원) ;
  • 공길영 (한국해양대학교 항해학부)
  • Received : 2016.07.08
  • Accepted : 2017.01.06
  • Published : 2017.02.28
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Abstract

The estimation of non-linear ship motion is one of the most important issues in recent studies of ship stability. In this paper, bispectral analysis and bicoherence analysis were introduced in order to analyze the non-linear ship motion. In addition to the previously observed non-linear pitching motion in following seas, this study observed the non-linear phase coupling of pitching motion in following & quartering seas, and starboard beam seas. By comparing phase coupling between each frequency quantitatively via the bicoherence analysis, it was confirmed that non-linear phase coupling was much stronger in frequency regions other than the peak frequencies of a power spectrum. Furthermore, it was found out that the results of bicoherence calculation were analagous to each other, although the different normalization methods were applied.

선체의 비선형적 동요현상은 선박의 감항성 확보와 관련하여 최근 활발하게 연구가 이루어지는 분야들 중 하나이다. 본 연구에서는 고차 스펙트럼 해석방법들 중 하나인 바이스펙트럼 해석방법과 바이코히어런스 해석방법을 적용하여 선체의 비선형적인 동요 현상을 해석하였다. 본 연구를 통해 기존에 알려진 추파상황에서의 비선형적 선체 종동요 현상과 더불어 추사파 및 우현 횡파 상황에서도 선체 종동요의 비선형 위상 동조 현상이 일어나는 것을 확인하였다. 또한, 바이코히어런스 방법을 통해 주파수간 비선형적 간섭현상을 수치화 하여 주파수 대역별로 위상 동조 현상을 비교할 수 있었다. 이를 통해 선체 종동요의 파워스펙트럼상의 피크 주파수 이외의 주파수 대역에서 비선형적 위상결합이 더 강하게 일어난다는 사실을 확인하였다. 이에 더하여, 바이코히어런스 해석방법은 정규화 방법에 크게 영향을 받지 않는 다는 사실 또한 확인하였다.

Keywords

References

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