• Journal of Korean Society of Coastal and Ocean Engineers
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• 제18권2호
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• pp.166-177
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• 2006

The accuracy impact of using high-order Boussinesq-type model as compared to the typical order model is examined in this paper. The multi-layer model developed by Lynett and Liu(2004a) is used for simulating of wave breaking over a shelf region. The nonlinearity of the waves tested, ${k_0}{A_0}$, ranges from 0.029 to 0.180. The overall agreement between the two-layer model and the hydraulic experiments are quite good. The one-layer model overshoals the wave near the breakpoint, while the two-layer model shoals at a rate more consistent with the experimental data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제7권2호
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• pp.141-147
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• 1995

Various numerical models for predicting wave deformation have been proposed. Among them a time-dependent mild-slope equation based on the line discharges and surface-elevation changes has been widely used in the wave fields with reflective waves. If applying this model to the case of obliquely-incident waves, not only the open-sea boundary but also one of the lateral boundaries should be treated as incident boundaries. In this study, Maruyama and Kajima (1985), Copeland (1985) and Ohnaka and Watanabe (1987)'s method are reviewed and the characteristics of these methods are analyzed using e normalized wave heights, wave angels and phases obtained from the numerical experiments. It is shown that Ohnaka and Watanabe(1987)'s method provides the most adequate driving boundary is the most suitable in e wave field with a general bottom slope.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제19권2호
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• pp.117-124
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• 1983

In rough seas, actual behaviours of a ship may not be estimated by the linear strip theory, because of Nonlinearities due to the hull shape, bottom slamming and bottom and/or bow-flare slamming. In case of slamming, impulsive hydrodynamic pressure occurs on the fore body surface of the ship, resulting hull vibration called whipping, by which the ship may suffer from serious structural damages and the impact pressure, depends critically on the relative velocity at re-entry. In this paper, the Time history of impact froce at each station, the longitudinal distribution of impact force at critical time, the Time history of acceleration at F.P. and the Time history of Bending moment at midship are illustrated. That is, authors analyzed Dynamic response of container ship to be subjected slamming impact force.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2005년도 추계학술대회 논문집
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• pp.147-152
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• 2005

선형파 이론에 의한 파랑스펙트럼 분포에 의해서는 30m 크기의 파랑은 현실적으로 거의 발생 불가능하다고 인식되어 왔다. 그러나 최근의 위성 영상을 이용한 조사에 의해 3주간의 기간 통안 25m 이상의 거대파가 10개 이상 관측됨에 따라 실해역에서 빈번히 마주칠 수 있는 현상임이 입증되었으며 이에 따라 지금까지 이유 불명으로 치부되어 왔던 많은 해양 재난이 거대파에 의해 발생했던 것으로 추정되고 있다. 거대파의 발생원인은 파군 형성과 관련한 파고분포 특성의 변화, 전파하는 파군의 비선형 공명간섭 통이 제기되고 있으나, 그 출현의 복잡성과 자료의 부족 등으로 아직 명확하게 해명되지 못하고 있다. 본 연구에서는 실해역에서 발생하는 거대파의 특성 및 선형 및 비선형이론에 근거한 거대파 발생 기구를 고찰하고 비선형 파랑전파를 모사할 수 있는 수치모형을 개발하였다.

• Journal of Ocean Engineering and Technology
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• 제11권2호
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• pp.107-112
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• 1997

본 연구는 자유표면 인삭을 위한 실험 기법 개발에 관한 연구이다. 2차원 수중익에 의해 발생되는 자유표면파를 연구대상으로 삼았다. 실험은 회류수조에서 행하였다. NACA 0012 수중익을 여러가지 길이와 2가지양각에 대해서 실험한 결과 생기는 비선형 자유표면 파를 인식할 수 있도록 영상처리 기술을 도입하였다. 실헙결과 얻은 자유표면 형상을 다른 연구자의 결과와 비교하였다. 비교결과 영상처리의 기법이 자유표면을 인식하는데 대단히 유용한 도구임을 알 수 있었다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 한국해안해양공학회 1995년도 정기학술강연회 발표논문 초록집
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• pp.91-94
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• 1995

비선형인 다방향파의 기본특성을 구명하는 기초적 인 연구단계로서, 2방향파 또는 3방향파 등의 유한진폭의 기본구성파 사이의 비선형간섭에 관한 연구가 50년 이전부터 진행되어왔다. 이러한 비선형간섭에 관한 연구는, 처음에 심해역을 중심으로 행해졌으며(Phillips, 1960； Longuet-Higgins, 1962； Su, 1982). 천해역을 대상으로 한 연구는, 경사입사파와 반사파 간의 비선형간섭(Hsu et al., 1979) 그리고 동일지상와 파고의 2방향파간의 비선형간섭(She.1991；Moriya ＆Mizuguchi,1994) 등이 있다. (중략)

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 한국해안해양공학회 1992년도 정기학술강연회 발표논문 초록집
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• pp.121-125
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• 1992

입사파와 반사파의 분리는 수리모형실험에 있어서 기본적이면서도 대단히 중요한 문제이다. 최근까지 개발된 분리기법으로는 Goda and Suzuki (1976)의 2점법과 Mansard and Funke (1980)의 3점범을 들 수 있다. 2점법은 두 지점에서의 파고를 관측하여 분리하는 기법으로 두 지점사이의 거리에 따라 해가 존재하지 않는 파랑조건이 존재하며 수조에서 발생되는 횡파, 비선형 파랑상호 간섭, signal noise, 측정오차 등에 민감한 단점이 있다.(중략)

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2021년도 추계학술대회
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• pp.37-38
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• 2021

해상에서의 통신은 파도의 움직임에 의해 내륙에서의 통신에 비해 어려움이 있다. 본 논문에서는 Bretschneider 스펙트럼 모델을 이용하여 Open-Ocean에서의 파도의 움직임을 모델링다. 내륙에 위치한 기지국과 내륙으로부터 일정 거리 떨어진 해상에 위치한 부표와의 해상통신 환경을 고려하였으며, 모델링한 파도의 움직임을 바탕으로 부표부터 기지국까지의 거리에 대한 각도와 기지국부터 Block되어 Non-Line of Site(NLoS)된 지점까지의 거리에 대한 각도를 비교함으로써 Continuous-LoS(CLoS)구간을 확보하기 위해 파고 대비 안테나의 높이를 변경하며 비교했다.

• Journal of Korea Water Resources Association
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• 제46권2호
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• pp.205-218
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• 2013

The likelihood of rip current at Haeundae beach according to wave parameters, such as wave height, period, direction, and tidal elevation, was estimated by using numerical simulations with a Boussinesq model, FUNWAVE. To examine the estimation, the rip current occurred on 12th June, 2011 at Haeundae beach was simulated based on observations. For the estimation, the following procedure was carried out. First, extensive numerical simulations of nearshore circulations are performed under various random sea conditions according to the wave parameters. Second, from the numerical results, cross shore components of two-wave-period averaged velocities over the nearshore area were computed, and their seawardly maximum was defined as rip current velocity of the area. Third, using time series of the rip current velocity, we computed the ratio of the simulation time and the time period in which the rip current velocity exceed a threshold velocity for rip-current accidents, and thus the ratio was quantified as the likelihood of rip current at Haeundae beach for the input wave parameters. From the resultant estimations, it was found that the rip current likelihood increases as wave height and period increase, and tidal elevation decreases.

• The Korean Journal of Physiology
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• 제16권1호
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• pp.41-50
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• 1982

The effects of $NaHCO_3$ on the electrocardiogram of rats were studied in the induced hyperkalemia. The subjects were divided into 4 groups: the group 1 was normal control and the data on this normal control had teen obtained from the following three groups before administration of KCl or $NaHCO_3$, the group 2 (KCl) was administered 40 ml per kg body weight of the 10 per cent KCl solution, the group 3 $(NaHCO_3)$ was administered 40 ml per kg body weight of the 10 per cent $NaHCO_3$ solution, and the group 4 $(KCl+NaHCO_3)$ was received 10 per cent KCl, which was followed by administration of 10 per cent $NaHCO_3$ at one and half hours later. In KCl, the heart rate was decreased rapidly, and then maintained its level, later rapid decreasing heart rate was followed by the cardiac stand still. The mean electrical axis of QRS complex became progressively deviated to the left. The amplitude of T wave was increased transiently but was not changed thereafter. There was prolongation of the P-Q interval and the Q-T interval at the beginning and then they were shortened. In $NaHCO_3$, the heart rate was decreased rapidly at the beginning, later showed a tendency of recovery. The mean electrical axis of QRS was not changed initially, but later became deviated to the left. The amplitude of T wave was not changed. There was prolongation of the P-Q interval and the Q-T interval at the beginning and then they were shortened. In $KCl+NaHCO_3$, there were a tendency of recovery of both the amplitude of the T wave and the electrical axis of the QRS complex after administration of $NaHCO_3$ but the heart rate was not recovered. There was prolonged P-Q interval, but the Q-T interval was relatively unchanged.