• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2014년도 춘계학술대회
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• pp.255-257
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• 2014

항내 정온도는 항만의 박지(泊地) 내 수면의 정온한 정도를 나타내는 것으로서, 선박의 접이안, 하역작업과 관계가 있지만 이보다 안전한 피항지로서의 최소한의 수역을 파악하기 위한 중요한 지표이다. 따라서, 항내 정온도 예측시 항외로부터 입사하는 파랑의 굴절, 회절, 천수 및 반사 등에 의한 항내파고 및 파향의 변화를 복합적으로 해석해야 한다. 그러나 항내 정온도 검토를 위하여 현재 운용 중인 수치모형실험은 각각의 특성에 따른 결과의 상이함에 따라 이에 대한 기본적인 재검토가 필요한 것으로 판단되며, 이에 본 연구에서는 후포항을 대상으로 수치모형실험결과와 비교함으로써 현재 운용 중인 모형의 타당성을 검토하였다.

• 대한토목학회논문집
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• 제14권3호
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• pp.607-618
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• 1994

항만(港灣)의 진동(振動)을 일으키는 발생원인(發生原因)을 규명하고자 항만(港灣) 진동해석(振動解析)에서 현재까지 고려되지 않았던 파군효과(波群效果)를 고려하였다. 동해항(東海港)과 임원항(臨院港)에 대한 항만의 공진주기는 경계적분(境界積分) 방정식법(方程式法)으로 구하였으며, 동해항(東海港) 입구에서 관측된 불규칙(不規則) 파군(波群)에 따른 장주기파(長週期波)는 잉여응력(剩餘應力) 이론(理論)과 에너지 이력개념(履歷槪念)을 이용하여 유도된 이론식(理論式)으로 구하였다. 주기(週期)의 관점에서 해석할 때 파군(波群)에 따른 장주기파(長週期波)는 어항(漁港)과 같은 소규모 항만(港灣)에 큰 진동을 일으킬 수 있으며, 산업항(産業港)과 같은 대규모 항만(港灣)에는 정박중인 선박(船舶)의 동요(動搖)를 일으키는 에너지원(源)이 될 수 있음을 규명(糾明)하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 Asia Navigation Conference
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• pp.3-13
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• 2004

The total tug capacity needed for berthing/de-berthing operations of a ship may vary depending on the ship type, size, loading conditions, and environmental circumstances. Traditionally, total tug capacity is determined based on the local guidelines of port authorities or on the rule of thumb. However, the social demands for the enhancement of ship safety at harbor and the economical demands for the cost-effectiveness of tug usage makes it necessary for port authorities to develop more reasonable and detailed guidelines on tug usage which takes various conditions into account. In this paper, the method to estimate the optimum tug capacity of VLCC is suggested by considering various ship conditions such as its size, loading conditions, and environmental circumstances such as wind, wave, tidal currents, and geographical characteristics of a terminal. This method is applied to a VLCC terminal located in Gwang-Yang Harbor of Korea and the results are compared with the local guidelines of the harbor, which shows that there may be a room for the amendment of local guidelines on tug usage.

• 산업기술연구
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• 제26권B호
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• pp.63-71
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• 2006

The concerned object of the construction industry is environment. It is one of the main purposes of today's construction that human can live reasonably in nature. This study is about the fish-road connecting hydraulic structure in the river with nature. Chapter 2, starting with the general investigation about fish-road and helps comprehension for relatively general fish-road such as necessity, establishment purpose, history, study example, relating domestic law, design condition, consideration and form of fish-road. Chapter 3, containing the present condition of fish-road facilities in Gangwon-Do and thoughts of the problems and general countermeasures of existing fish-road. Chapter 4, Having Examined compatibility by amount of flowing water through hydraulic model test in the Ice harbor I-type model. chapter 5, Analyzation and arrangement to efficient establishment plan of fish-road and the result of the hydraulic model experiment to be beaconed a little in forward fish-road study. In the hydraulic model test result, when we suppose establishment of 1~3 in slope of 1/20, could know that applicable drought flow of the river is $0.06{\sim}3.0m^3/sec$ in case of Ice harbor I-type which transforming Ice harbor that was invented as studying project of the Ministry of Environment.

• 대한토목학회논문집
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• 제13권3호
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• pp.173-183
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• 1993

장주기파(長週期波)의 침입(侵入)에 의한 항내(港內) 수면교란(水面攪亂) 현상(現象)을 분석(分析)하기 위하여 동해항(東海港)의 항외(港外), 항입구(港入口) 및 항내(港內)의 4개(個) 정점(定點)에서 약 1개월간(1992. 2~3) 수압식(水壓式) 파고계(波高計)를 이용하여 현장관측(現場觀測)을 실시(實施)하였다. 관측자료(觀測資料)의 스펙트럼 분석(分析) 결과(結果) 동해항(東海港)의 Helmholtz natural period는 약 17.1분, 제(第)2 첨두주기(尖頭週期)는 약 5.5분이 되는 것으로 나타났다. Helmholtz natural period에서의 증폭비(增幅比)는 약 10으로 영일제(迎日濟)의 약 2에 비해 상당히 크게 나타났으나 관측기간중(觀測期間中)의 항내(港內)에서의 해수의(海水位) 변위(變位) 진폭(振幅)은 약 10cm로 비교적 작은 것으로 나타났다.

• 대한조선학회논문집
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• 제30권1호
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• pp.87-93
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• 1993

본 논문에서는 항만안에 계류된 선박의 비대칭 운동응답(Sway-Yaw)을 취급하였으며, 사각형 모형항만안에 계류된 선박의 운동을 계측하여 항만내 선박의 운동특성을 밝혔다. 해석해는 유체영역을 해양과 항만영역 그러고 선체주위영역으로 나누어 각 영역에서 경계치문제를 독립적으로 푼 다음, 인접한 영역의 해와 정합하여 미지수를 구하는 정합점근전개법을 사용하였다. 계산치와 실험치는 정성적으로 서로 비슷한 경향을 보이고 있으나, 정량적으로 차이가 있음을 확인하였다. 이는 수식전개 과정중에서 고려하지 않은 점성의 영향과 비선형성 그리고 경계벽에서 파의 부분반사에 기인하였으리라 추정된다.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2003년도 한국해안해양공학발표논문집
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• pp.208-215
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• 2003

Convective-diffusion equations appear in various disciplines such as hydrology, chemical engineering and oceanography dealing with the transport problem of scalar quantities. Since it is nonlinear, numerical methods are generally used to obtain its solution. Very limited number of analytical solutions are available usually in cases when the convective velocity is constant or has a simple functional form (for some collection of the solutions, see Noye, 1987). There is however a continuing need to develop analytical solutions because of its practical importance. Analytical solutions of the convection-diffusion equation are valuable not only for the better understanding on the transport process but the verification of numerical schemes. (omitted)

• 한국해양공학회지
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• 제20권2호
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• pp.36-40
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• 2006

As large waves enter a harbor, during their propagation, the motions a floating body are large and if may even be damaged by waves. This phenomenon may be caused by harbor resonance, resulting from large motion at low wave frequency, which is close to the natural frequency of a vessel. In order to calculate the motion of a floating body in a harbor, it is necessary to use the wave forces containing the body-harbor interference. The simulation program to predict the motions of a floating body by waves in a harbor is developed, and this program is based on the method of velocity potential contiuation method proposed by Ijima and Yoshida The calculated results are shown by the variation of wave frequency, wave angle, and the position of a floating body.

• Journal of Ship and Ocean Technology
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• 제11권1호
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• pp.36-46
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• 2007

The maintenance of a ship is essential for safe navigation and hence regular surveys are prescribed according to the rule of classification societies. A hull inspection is generally performed by professional divers, but it takes a long time and the efficiency is low in terms of time and cost. In this research, a ROV(Remotely Operated Vehicle) named as SNU-ROV(Seoul National University-ROV) is developed to replace the conventional inspection method. In this system, the ROV is intended to be used for inspecting ship and harbor because harbor inspection is merging as a safety measure against any possible terror actions. In order to increase the efficiency of inspection, the ROV must be able to measure the exact position of damages. SNU-ROV has a positioning system based on LBL(Long Base Line). In shallow water such as harbor, however, LBL has bad DOP(Dilution of Precision) in the depth direction due to the limited depth. Thus LBL only can not locate the exact depth position. To solve the DOP problem, a pressure sensor is introduced to LBL and a complementary filter is attached by using indirect feedback Kalman filter. Thus developed positioning system is verified by simulation and experiment in towing tank.

• Smart Structures and Systems
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• 제10권6호
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• pp.517-546
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• 2012

In this paper, vibration-based methods to monitor damage in foundation-structure interface of harbor caisson structure are presented. The following approaches are implemented to achieve the objective. Firstly, vibration-based damage monitoring methods utilizing a variety of vibration features are selected for harbor caisson structure. Autoregressive (AR) model for time-series analysis and power spectral density (PSD) for frequency-domain analysis are selected to detect the change in the caisson structure. Also, the changes in modal parameters such as natural frequency and mode shape are examined for damage monitoring in the structure. Secondly, the feasibility of damage monitoring methods is experimentally examined on an un-submerged lab-scaled mono-caisson. Finally, numerical analysis of un-submerged mono-caisson, submerged mono-caisson and un-submerged interlocked multiple-caissons are carried out to examine the effect of boundary-dependent parameters on the damage monitoring of harbor caisson structures.