• 한국군사과학기술학회지
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• 제27권5호
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• pp.581-587
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• 2024

The mast structure of a naval ship has a lot of expensive equipment attached and is easily exposed to strong vibration due to its structural characteristics, so it is necessary to manage vibrations well to prevent equipment failure and increase operating time. Since September 2015, the Navy has been managing the vibration of the ship's mast structure with a separate tolerance standard from the local vibration, but this standard is set at 1/2 of the vibration limits for mast-mounted equipment without any engineering basis. So the establishment of new vibration limits based on the operating conditions of naval ships is required. In this study, the mast structure vibration limits were reviewed considering the actual operating time of naval ships, and the results were compared with the standards of major overseas classification societies and the actual measurements of a ship that had mast structure vibration problems.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2019년도 춘계학술대회
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• pp.300-302
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• 2019

민간 선박은 물론 함정에서 가장 높은 구조물인 마스트는 주로 레이더와 항해등이 탑재되는 곳이다. 특히 많은 통신장비를 운용하는 해군 함정 특성상 함정 마스트에는 레이더는 물론 통신용 안테나, 항공기 유도용 TACAN 등 여러 종류의 안테나가 탑재된다. 마스트 자체의 복잡한 구조는 물론 설치된 안테나는 RCS를 크게 만드는 요인이 되기 때문에 미국, 유럽 등에서는 RCS를 줄이기 위한 마스트 기술이 개발되어 적용되고 있다.

• Structural Engineering and Mechanics
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• 제32권4호
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• pp.517-529
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• 2009

A passive vibration mitigation architecture is proposed to damp transverse vibrations of guyed masts. The scheme is based on a number of pendula attached to the mast and tuned to the vibration modes to be controlled. This scheme differs from the well-known autoparametric pendulum absorber system. The equations of motion of the guyed mast with an arbitrary number of pendula are obtained. The leading bending behaviour of a typical truss mast is described by an equivalent beam model whereas the guys are conveniently modeled as equivalent transverse springs whose stiffness comprises the elastic and geometric stiffness. By assuming a mast with an inertially and elastically isotropic cross-section, a planar model of the guyed mast is investigated. The linearization of the equations of motion of the mast subject to a harmonic distributed force leads to the transfer functions of the structure without the dampers and with the dampers. The transfer functions allow to investigate the mitigation effects of the pendula. By employing one pendulum only, tuned to the frequency of the lowest mode, the effectiveness of the passive vibration potential in reducing the motion and acceleration of the top section of the mast is demonstrated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1273-1274
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• 2011

• 한국산학기술학회논문지
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• 제22권5호
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• pp.98-107
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• 2021

차기군수지원함(AOE-II) 풍향풍속계 장비에 대해서 항해시운전평가 결과, 함의 우현에서는 40~90도 부근, 좌현에서는 270~320도 부근에서 풍향풍속 검출기 움직임 오작동 현상이 발생되었다. 위의 현상에 대한 원인을 분석하고 개선하는 것이 본 연구의 목적이었다. 원인 추정으로 풍향풍속 검출기가 마스트 구조물에 가려져서 불어오는 바람의 직접적인 영향을 받지 않게 되고, 마스트 구조물 뒤쪽으로 와류 기류가 형성되어 움직임 오작동 현상을 발생시켰다고 추정하였다. 위의 문제를 해결하기 위해서 신규 설치되는 마스트 야드에 풍향풍속 검출기를 이동 설치하는 방안을 검토하였다. 진동 해석을 실시하여 진동 영향성을 검토 후 신규 마스트 야드에 풍향풍속 검출기를 설치하여 항해시운전평가로 검증하였다. 개선 방안이 일부 유효하여, 신규 마스트 야드에서 풍향풍속 검출기 위치를 마스트와 이격하여 이동 설치 후 항해시운전평가로 다시 검증하였다. 풍향풍속 검출기 움직임 오작동 현상이 더 이상 발생하지 않아서 적절한 개선방안으로 확인되었다.

• 전기전자학회논문지
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• 제24권1호
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• pp.238-242
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• 2020

본 논문에서는 구축함에 탑재되는 통합 마스트의 RCS(Radar Cross Section) 값을 저감시키기 위해 다층 구조로 되어있는 유전체 코팅을 이용한 기법을 제시한다. 제시된 다층 구조는 특별히 고유전율을 요구하거나 전자기파 흡수 차단에 많이 사용되는 자성체성분을 포함하지 않은 일반적인 유전체를 사용할 수 있도록 유전율의 범위를 정했기 때문에 제작에 용이하다는 장점이 있다. 제시된 다층 유전체 구조를 통합 바스트 형상에 적용시킨 후 시뮬레이션을 진행한 결과 다층 구조가 없는 구조물과 비교하여 6GHz에서 10.9dB, 12GHz에서 11.95dB, 18GHz에서 11.63dB의 RCS 저감 성능이 있는 것을 확인하였다.

• Wind and Structures
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• 제9권5호
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• pp.387-396
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• 2006

This paper presents the wind characteristics of Typhoon Dujuan as measured at a 50 m guyed mast in Hong Kong. The basic wind speed, wind direction and turbulent intensity are studied at two measurement levels of the structure. The power spectral density of the typhoon is compared with the von Karman prediction, and the coherence between wind speeds at the two measurement levels is found to This paper presents the wind characteristics of Typhoon Dujuan as measured at a 50 m guyed mast in Hong Kong. The basic wind speed, wind direction and turbulent intensity are studied at two measurement levels of the structure. The power spectral density of the typhoon is compared with the von Karman prediction, and the coherence between wind speeds at the two measurement levels is found to compare with Davenport's prediction. The effect of typhoon Dujuan on the response of the structure will be discussed in a companion paper (Law, et al. 2006).with Davenport's prediction. The effect of typhoon Dujuan on the response of the structure will be discussed in a companion paper (Law, et al. 2006).

• Wind and Structures
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• 제20권3호
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• pp.405-422
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• 2015

In previous model- and full-scale studies, high-amplitude vertical vibrations of mast-arm traffic signal structures have been shown to be due to vortex shedding, a phenomenon in which alternatingly shed, low-pressure vortices induce oscillating forces onto the mast-arm causing a cross-wind response. When the frequency of vortices being shed from the mast-arm corresponds to the natural frequency of the structure, a resonant condition is created causing long-lasting, high-amplitude vibrations which may lead to the fatigue failure of these structures. Turbulence in the approach flow is known to affect the cohesiveness of vortex shedding. Results from this full-scale investigation indicate that the surrounding terrain conditions, which affect the turbulence intensity of the wind, greatly influence the likelihood of occurrence of long-lasting, high-amplitude vibrations and also impact whether reduced service life due to fatigue is likely to be of concern.

• Wind and Structures
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• 제9권5호
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• pp.397-412
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• 2006

This paper presents the wind excited acceleration responses of a 50 m guyed mast under the action of Typhoon Dujuan. The response of the structure is reconstructed from using a full finite element model and an equivalent beam-column model. The wind load is modelled based on the measured wind speed and recommendations for high-rise structures. The nonlinear time response analysis is conducted using the Newton Raphson iteration procedure. Comparative studies on the measured and computed frequencies and acceleration responses show that the torsional vibration of the structure is significant particularly in the higher vibration modes after the first few bending modes. The equivalent model, in general, gives less accurate amplitude predictions than the full model because of the omission of torsional stiffness of the mast in the vibration analysis, but the root-mean-square value is close to the measured value in general with an error of less than 10%.

• 한국산업융합학회 논문집
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• 제26권5호
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• pp.937-943
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• 2023

In this study, the mast cover of submarine was reverse engineered and structural analysis was performed. In order to print with the 3D printer, the modeling was reduced to 1/5 size by applying geometric similarity. From the structural analysis results, it was found that the maximum value of equivalent stress generated in the mast cover was 180.9 MPa. This stress value occurs on the inner surface in the major axis. As a result of applying the load condition at a diving depth of 600 m, the mast cover is in a completely elastic state. The 1/5 size model printed on FDM 3D printer with PLA filament was the same as the reverse engineered modeling and it was printed in a perfect shape with no apparent defects. The 1/5 size model printed on PBF 3D printer with SUS316L powder was perfectly manufactured with no apparent defects.