• 대한조선학회논문집
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• 제44권3호
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• pp.267-278
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• 2007

This experimental study investigated on the eddy making effect on the roll motion of a rectangular barge in a two-dimensional wave tank. The structure was used to simulate a simplified rectangular barge in the beam sea condition. The structure with a draft one half of its height was hinged at the center of gravity and free to roll by waves. The rectangular barge was tested with regular waves with a range of wave periods that are shorter, equal to, and longer than its roll natural period. Particle image velocimetry (PIV) was employed to obtain the velocity field in the vicinity of the structure. The coupled interactions between the incident wave and the barge were demonstrated by examining the vortical flow fields to elucidate the eddy making effect during the roll motion. For incoming wave with a wave period same as the roll natural period, the barge roll motion was reduced by the eddy making damping effect. At the wave period shorter than the roll natural period, the structure roll motion was slightly reduced by the vertical flow around the barge. However, at the wave period longer than the roll natural period, the eddy making effect due to flow separation at structure corners indeed amplifies the roll motion. This indicates that not only can the eddy making effect damp out the roll motion, it can also increase the roll motion.

• 대한조선학회논문집
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• 제52권2호
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• pp.135-142
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• 2015

The Anti-Rolling Tank(ART) has an advantage over the other roll stabilizing devices, when ship is staying and working at one site of sea. An important design point of ART is the tank tuning, that is, matching the tank natural period to the ship's roll natural period. Since the load condition and consequently the roll natural period of ship is to be changed widely, the natural period of ART also has to be changed widely. In case of the existing U-tube type ART with a single layer duct, the tank natural period can be changed in a relatively narrow range. This paper suggests a new U-tube type ART system using a double layer duct to enable wide change of ART natural period. Through the roll experiments performed in regular beam waves for a box-type model ship, it is shown that the double layer duct ART has about two times wider period range and a better reducing effect of roll magnitude than the single layer duct ART.

• 한국해양공학회지
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• 제19권3호
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• pp.25-30
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• 2005

To predict rolling performance for a barge-type FPSO, the evaluation of correct nonlinear roll damping is critical. The square section of FPSO causes a considerable viscous damping effect. Free roll decay tests were carried out to estimate nonlinear roll damping for a barge-type FPSO, under three different conditions. The roll motion RAO was deduced from model tests in the wave condition of the wideband spectrum. In numerical calculation, the quadratic damping was considered as equivalent linear damping, using the results of free roll decay test. Tested roll performance in the JONSWAP wave spectrum was compared with numerical results. These two results shaw good agreement, in spite of the proximity of peak wave period and roll natural period.

• 수산해양기술연구
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• 제52권4호
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• pp.339-346
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• 2016

The aim of this research was to the experimental data using statistical and spectral analyzing method to get the motion reponses of a stern trawler in operation states such as drifting, sailing and trawling according to the wave height. In drifting, the significant and the maximum valuer of roll in beam sea increased according to the wave height, but those of pitch decreased. The response and the period of peak of roll in beam sea were increased, but those of pitch decreased. In navigation, the significant and maximum values of roll increased remarkably according to the wave height, but those of pitch changed a little. The response of roll was highest in quartering sea, beam sea and then following sea, but those of pitch was highest in bow sea, head sea and then beam sea in the order of all wave heights. The period of peak of roll due to the wave height and the wave direction changed from 3.8 to 9.9 seconds, and those of pitch changed from 3.3 to 10.4 seconds. In trawling, the significant and maximum values of roll increased a little according to the wave height, but those of pitch increased significantly. The response of roll was highest in beam sea, bow sea and then quartering sea, but those of pitch was highest in head sea, following sea, and then beam sea in the order. The period of peak of roll due to the wave height and the direction changed from 6.6 to 10.9 seconds, and those of pitch changed from 6.7 to 11.2 seconds.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.183-187
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• 2004

To predict rolling performance for a barge-type FPSO, the evaluation of correct nonlinear roll damping is critical. The squall section of FPSO causes a fair amount of viscous damping effect. Free roll decoy tests were conducted to estimate nonlinear roll damping for a barge-typ FPSO of three different loading conditions. The roll motion RAO was deduced by model tests in the wave condition of wideband spectrum. In numerical calculation, the quadratic damping was considered as equivalent linear damping using the results of free roll decay test. Tested roll performance in JONSWAP wave spectrum was compared with numerical results. These two results show good agreement, in spite of proximity in peak wave period and roll natural period.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.30-35
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• 2004

Several roll motion reduction devices are reviewed and suggested for the application in FPSO. The firstly suggested solution is the shape of the bilge. The next is a bilge keel. The last suggestion is the ART (anti-rolling tank). Typical U-tube type ART is designed for a FPSO and examined extensively by model experiment. The model section was made of transparent acryl. Free decay test, forced oscillation test and wave test were carried out at a two-dimensional wave flume. U-tube type ART is effective only when the natural periods of ART and ship are same. Therefore, the divided U-tube type ART with split plate is suggested for the reduction of the roll motion of a FPSO over the wide range of the roll period.

• 한국의류학회지
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• 제20권2호
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• pp.323-335
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• 1996

The objective of this treatise is to study the effect which rock'n'roll had on fashion through the fashion of rock'n'roll stars and contemporary youngsters. The United states of America in the 1950's when rock'n'roll came into existence was an opulent and luxurious period. People's spare time increased and teenagers who grew up in oppulence after World War II emlerged. It was rock'n'roll that comprised the background of their culture. Rock'n'roll music, which was in the mixed form of Negro's rhythm and blues, and country -and-western of Southern hillbilly Rock'n'roll was expressed as a 'culture', characterized by both the luxurious and oppulent culture and the'anti-establishment' defying it. This cultural characteristic emerged as at once the conservative fashion following the contemporary fashion and the anti-establishment fashion in the rock'n'roll fashion. Therefore, the rock'n'roll fashion influenced by popular music became one momentum of including popular music among factors affecting the twentieth-century modern fashion.

• 해양환경안전학회지
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• 제21권5호
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• pp.538-542
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• 2015

선체의 횡관성모멘트는 선박의 횡운동 특성을 다루는 경우 제외될 수 없는 요소로서 그 크기의 적정성은 선체 동특성 해석의 결과와 신뢰성에 큰 영향을 미친다. 그러나 선박은 질량분포와 형상이 복잡하므로 이를 직접적인 계산을 통해 값을 구하기에는 과정이 매우 복잡하고 대상 선박의 구체적인 관련 자료를 얻기도 어렵다는 점에서 실용적으로는 선체 질량의 등가적 관성반경을 선체폭의 일정비율로 계산하는 간접적인 방법이 통용되고 있다. 한편, 어느 선체의 자유 횡운동이 나타내는 횡요 주기와 감쇠형태는 관성모멘트에 의해 영향을 받기 마련이고 따라서 이러한 응답의 결과적인 모양으로부터 역으로 해당 선박의 관성모멘트를 구하는 일반식의 도출이 가능할 것으로 유추될 수 있다. 본 연구에서는 관찰에 의한 선체의 횡요 주기는 경사각의 진폭 감쇠비에 의해서도 달라지는 관계를 해석하여 횡요 주기와 경사각 진폭 감쇠비 모두를 함수 인자로 포함하는 일반식에 의해 횡관성모멘트 크기가 구해질 수 있음을 나타내었다. 또한 이러한 일반식에 횡요 관찰 선박의 주요 제원을 적용하였을 때 나타나는 특성 그래프들을 분석한 결과 횡요주기뿐 아니라 진폭감쇠비가 함께 검토될 때 얻어지는 관성모멘트 값이 보다 정확해진다는 것을 확인하였다.

• 해양환경안전학회지
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• 제29권4호
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• pp.380-388
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• 2023

본 연구는 모형선박의 횡방향 무게분포를 변화시키면서 횡요주기 및 관성모멘트에 의한 GM을 추정하고 경사시험으로 계측되는 GM 값과 비교한다. 그 과정에서 각 수치를 분석하여 관계성을 파악한다. 실험 및 비교에 사용된 선박의 종류는 3종류로 7톤급, 20톤급 어선과 KVLCC의 모형선을 사용하였다. 실험은 스윙프레임 테스트와 자유 횡요 감쇠테스트를 수행하여 관성모멘트와 횡요주기를 계측하고, 경사시험으로 GM을 계측하였다. 관성모멘트와 횡요주기로 추정된 GM과 경사시험으로 구해진 GM은 선박의 무게 분포 변화에도 동일한 경향을 보였지만, 경사시험에서 구해진 GM이 더 작은 값을 보였다. 따라서 GM 추정 시에 관성모멘트나 횡요주기 외에도 추가적인 보정 계수나 파라미터가 필요하다고 판단된다. 추후 무게중심을 변화시켜 추정 GM과의 관계를 분석하여 보정 계수를 산출할 계획이다.

• 산업공학
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• 제22권1호
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• pp.85-94
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• 2009

Nowadays, most of the major manufacturing companies prepare their manufacturing schedule using package based solutions. Even though the accuracy of the detail scheduling result is high at implementation, however, it is low during maintenance period. The main cause of low accuracy during maintenance period is due to difficulties in maintaining the accurate level of master data. In this paper, we propose to easily maintain setup time, which is one of the most important factors required in master data to achieve good scheduling result, after changing job. This paper is mainly focused on how to deduce the factors that influence the setup time in a roll-based manufacturing field with print operations. For this purpose, we employed rule based algorithm and applied for deciding setup time for the existing product items. Likewise, it can be applied to new items without any complex setup procedures, and, finally, it displays the result of the real setup-time and calculated setup-time.