• International Journal of Naval Architecture and Ocean Engineering
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• 제9권5호
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• pp.499-508
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• 2017

This paper uses optimization techniques to obtain bow hull form of a 66,000 DWT bulk carrier in calm water and in waves. Parametric modification functions of SAC and section shape of DLWL are used for hull form variation. Multi-objective functions are applied to minimize the wave-making resistance in calm water and added resistance in regular head wave of ${\lambda}/L=0.5$. WAVIS version 1.3 is used to obtain wave-making resistance. The modified Fujii and Takahashi's formula is applied to obtain the added resistance in short wave. The PSO algorithm is employed for the optimization technique. The resistance and motion characteristics in calm water and regular and irregular head waves of the three hull forms are compared. It has been shown that the optimal brings 13.2% reduction in the wave-making resistance and 13.8% reduction in the added resistance at ${\lambda}/L=0.5$; and the mean added resistance reduces by 9.5% at sea state 5.

• 한국태양에너지학회 논문집
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• 제31권5호
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• pp.47-59
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• 2011

The purpose of this paper is to simulate the high ozone concentration in Shiwha Banwol indusrial complex. High pollution episodes (ozone alert) of this area are the results of geographical location and its air pollutants emission. This research has used meteorological model (RAMS) and photochemical air pollution Model (CIT model). As first step of the evaluate of this combined model system simulations are done in terms of meteorological characteristics like wind fields, PBL-height, etc.. Numerical simulations are carried out with real meteorological synoptic data on June. 24-25, 2010. In comparison with real measurement and another research the model reflects well local meteorological phenomena and shows the possibility to be utilized to analyse the pollutant dispersion over irregular terrain region. The high ozone concentration is deeply correlated to the ambient air temperature, wind speed and solar radiation. Local meteorological phenomena like sea-land breeze impact on horizontal dispersion of ozone. This analysis of meteorological characteristics can, in turn, help to predict their influences on air quality and to manage the high ozone episodes.

• 대한조선학회논문집
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• 제52권3호
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• pp.187-197
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• 2015

This study aims the development of a semi-analytic method for the parametric roll of large containerships advancing in longitudinal waves. A 1.5 Degree-of-Freedom(DOF) model is proposed to account the change of transverse stability induced by wave elevations and vertical motions (heave and pitch). By approximating the nonlinearity of restoring moment at large heel angles, the magnitude of roll amplitude is predicted as well as susceptibility check for parametric roll occurrence. In order to increase the accuracy of the prediction, the relationship between righting arm(GZ) and metacentric height(GM) is examined in the presence of incident waves, and then a new formula is proposed. Based on the linear approximation of the mean and first harmonic component of GM, the equation of parametric roll in irregular wave excitations is introduced, and the computational results of the proposed model are validated by comparing those of weakly nonlinear simulation based on an impulse-response-function method combined with strip theory. The present semi-analytic doesn’ t require heavy computational effort, so that it is very efficient particularly when numerous sea conditions for the analysis of parametric roll should be considered.

• 한국해양공학회지
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• 제20권4호
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• pp.83-90
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• 2006

Recently, as the technology of utilization for the ocean space is being advanced, floating structures are asked for being mare and mare huge-scale. A very large floating structure(VLFS) is considered as a flexible structure, because of a quite large length-to-breadth ratio and its geometrical flexibility. The main object of this study is to develop an accurate and convenient method on the hydroelastic response analysis of very large offshore structures on the real sea states. The numerical approach for the hydorelastic responses is based on the combination of the three dimensional source distribution methods, the dynamic response analysis method and the spectral analysis method. A model is considered as many rigid bodies connected elastic beam elements. The calculated results shaw good agreement with the experimental and calculated ones by Ohta.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1673-1677
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• 2008

A method of construction with a basis treatment that uses a latticed bamboo mat puts bamboo's peculiarity and bamboo mat's bending substance to use, and a latticed bamboo mat equally distributes to embankment loading in a basis ground. Therefore it prevents ground destruction by an ill-balanced load and an irregular ground subsidence, and it makes safety system. This investigation make progress a soil box model by a dredged reclamation ground of west and south sea at domestic area, and make a comparative study and analyze the strengthening effect based on a grid size of a bamboo-mat and ground failure that it will use in the field.

• 대한조선학회논문집
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• 제44권4호
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• pp.360-369
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• 2007

When a large ship is advancing in waves, ship undergoes the hydroelastic response, and this have influence on structural stability and the fatigue destruction etc. of ship. The main objective of this research is to develop an accurate and convenient method on the hydroelastic response analysis of ships on the real sea states. We analyzed hydroelastic responses, which is formulated by finite element method. The numerical approach for the hydroelastic responses is based on the combination of the three dimensional source distribution method, the dynamic response analysis and the spectral analysis method. The calculated results show good agreement with the experimental and calculated ones by Watanabe.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2018년도 춘계학술대회
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• pp.197-198
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• 2018

종래의 연안역의 활용을 위한 개발사업 뿐만 아니라 최근에는 해양레저스포츠 및 해양에너지의 개발 등을 통해 해양활용에 관한 다변화된 수요가 증가하고 있다. 안전하고 경제적인 해양의 활용을 위해 파랑특성의 파악은 매우 중요하다. 관측파랑데이터를 활용하여 종래의 연구들에서 제안된 불규칙한 해상상태를 대표하기 위한 파랑변수들을 도출하고 이들의 관계를 검토함으로서 실제 해양파의 특성을 확인하고자 한다.

• 한국해양바이오학회지
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• 제5권4호
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• pp.46-50
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• 2011

Phytoplankton forms the base of sea ecosystems. Various environmental factors and anthropogenic pollution, primarily, affect the concentration and photosynthetic activity algal cells, and the changes in the phytoplankton photosynthesis influence other elements of aquatic ecosystems. The increase in anthropogenic pollution markedly damages natural aquatic ecosystems, particularly, in the coastal zones, where an intense blooming of microalgae occurs, including the release of highly dangerous ecotoxic substances of various chemical natures (red tides). In this study, we tried to apply as a parameter for the algal blooming prediction in the ocean from fluorescence values in the taken samples around Busan coastal area. F0 value was almost constant but Fv/Fm value showed the irregular pattern. We presume that these results are due to the changes of the ocean environment and climate. To predict or give early warning the algal blooming, we need to investigate the specific area or fixed area through real-time monitoring. Especially, algal blooming prediction or warning can be achieved via continuously monitoring and interpretation of fluorescence changes.

• 대한조선학회논문집
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• 제58권2호
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• pp.112-120
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• 2021

The novel wave generating system of a wave flume has been devised by utilizing the analytic solution of wave board motion in idealized two dimensional space. The arbitrary oscillation motion of submerged wave board segment has been defined by sinusoidal motion of upper and lower end of the wave board. The analytic solution of the wave board motion has been represented by the solution of board motion due to flap motion and swing motion. Arbitrary oscillation of the board could be specified by determining amplitude, frequency, and the phase lag. A novel hybrid wave generator could be operated not only in piston motion but also in flap or swing motion by selection of control parameter. The wave generator has unique motion enhancing ability by appending flap motion or swing motion to piston motion in wave generation. In addition the hybrid wave generator has advantages in generating high quality wave spectrum of irregular wave in simulating real sea condition.

• 자원환경지질
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• 제45권6호
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• pp.685-695
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• 2012

본 연구는 현재까지 수행된 독도 화산체 정상부 해역의 정밀수심 및 지구물리 조사 자료를 종합하고 분석하여 정상부 해역의 정밀해저지형 및 지구물리학적 특성을 연구하였다. 독도 연안역 동도와 서도 사이 연결 수로는 약 10 m 이내의 얕은 수심을 이루고 있다. 독도 화산체 정상부해역의 전체적인 수심은 동도와 서도의 육지부부터 수면 아래 약 30 m 까지는 불규칙하며 급한 경사면을 가지고, 그 후 수심 약 30 m부터 수심 약 80 m 까지는 경사가 점차 낮아지다가 수심 약 80 m 이하로 완만한 경사를 보이면서 외해역으로 깊어진다. 독도 육지부와 그 북동쪽 및 북서쪽으로 연장되는 암반들은 독도를 생성시킨 화구륜의 잔해로 판단되며 동도와 서도는 화구륜의 남쪽 한부분일 가능성이 큰 것으로 생각된다. 또한 정상부 해역의 해저지형에서는 소규모의 움푹 패인 지형들이 나타나는데 이는 독도 형성 후 나중에 생성된 소규모 분화구의 흔적들로 추정된다. 독도 정상부 해역은 주로 암반이 많이 분포하지만 곳곳에서는 모래 퇴적층들도 나타나는 것을 볼 수 있다. 독도 화산체 정상부에는 계단형의 경사면들이 나타나는데 이는 제4 기에 나타난 해침, 해퇴 등 해수면변화에 의해 만들어진 해저단구로 유추되며, 지역별로 차이가 있기는 하지만 주로 약 30 m, 60 m, 80 m 및 약 100 m의 수심대를 위주로 하여 몇 개의 주요 해저단구가 나타나는 것으로 판단된다. 자기이상도 및 아날니틱신호도를 살펴보면 수면 위 독도에서 연장되는 북동 및 북서쪽의 이상대들은 화구륜의 잔해로 예상되는 암반들의 위치와 유사하게 나타난다.