• Proceedings of the Korea Water Resources Association Conference
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• 1980.08a
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• pp.44-46
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• 1980

파의 에너지 감쇠기구의 관점에서 볼 때 분류손실방식인 유공벽식 방파제 중에서 원형공이 벽 전체에 균일하게 분포되어 있고 구멍 직경에 비해 벽 두께가 얇은 삼중 유공벽형 Caisson의 각 벽에 작용하는 파력에 고나해 이론적 접근과 실험을 통한 실증을 시도해 보았다. 이론적인 방법으로는 토굴구효남의 이론을 응용하였으며 주어진 파랑조건에 대해 각 유공벽 전 후면에 연속방정식과 Bernoulli 방정식을 이용하여, 각 영역별 연속 Potential의 진폭과 위상각에 대한 비선형 12원 연립방정식을 만들었고 Computer를 이용하여 반복법으로 각 속도 Potential을 확정하였다. 이렇게 구한 속도 Potential을 압력방정식에 대입하여 각 벽별 파력을 계산하였으며 동일한 파랑조건하의 실험에서 각 벽별 파력을 측정하여 양자를 서로 비교검토하였다. Bernoulli의 방정식중 에너지 손실항은 의사비선형으로 처리하였다. 유공율조합 0.25-0.3-0.2이고, 판두께가 1cm인 모형의 실험결과, 각 벽별 최대파력치의 특성으로서는 첫때, S-2, S-3등 간벽에 작용하는 파력이 전벽 및 후벽에 비해 두드러지게 작다는 사실과, 둘째 작용파력의 크기 순이 파형경사가 작을 때는 대략 S-4, S-1, S-2, S-3순이고 파형경사가 클 때에는 대략 S-1, S-4, S-2, S-3순이라는 점 등을 들 수 있겠다. 굴구효남이 가정한 f의 치 1.5를 사용하여 계산한 각 벽별 최대파력을 실험치와 비교해 본 결과, 파가 각 유공벽을 통과할 때의 손실수두를 실험에서의 양만큼 fr=1.5를 가정한 수학적 model이 설명해 주지 못한다고 볼 수 있으므로 두가지 방법에 의하여 본 실험에서 사용한 유공판의 손실계수를 근사적으로 추정하여 보았다. 추정한 f를 사용하여 다시금 각 벽별 최대파력을 계산하고 실험치와 비교해 보면 훨씬 서로 근접함을 알 수 있었다. 결국 본 논문의 이론을 사용하면 유공Caisson문제의 전체적인 윤곽 및 각 변수들의 파력에 대한 영향을 파악할 수 있겠다.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.35-43
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• 2020

Currently, cofferdams of circular cross section are widely applied as temporary facilities for the installation of bridge foundations in river/sea bridge construction in Korea. Existing caisson, sheet pile, and cell type cofferdam are widely used, but these methods take a lot of time and cost for installation and dismantling. In the case of the existing sheet pile construction method, attention is needed to secure internal and external stability because of the damage to the sheet pile due to ground penetration and difficulty in connecting element members. In this study, penetration design of circular steel pipes using suction pressure was performed on the soft ground of the west coast, and it was confirmed that penetration construction using suction pressure was possible through field tests. It was confirmed that applying the ground analysis results using the cone penetration test (CPT) to the design rather than the standard penetration test (N value) results more similar to the field test results. In addition, it was confirmed that local failure of the inside of the cofferdam was induced when a suction pressure higher than the upper limit suction pressure was applied in the silty sand.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.420-433
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• 2020

In order to increase the stability of existing breakwater, new caissons are installed on the back or the front of existing caissons. It is very important to evaluate wave force and wave run-up according to the change of porosity among caissons and the energy loss due to separation effects. In this study, we use the eigenfunction expansion method with Darcy's law, which describes the flow of a fluid through a porous plate, to analyze the characteristics of wave on circular breakwater of double array for various porous coefficients. To verify the numerical method, the comparison between present results and Sankarbabu et al. (2008) is made. The wave force and the wave run-up acting on each dual cylindrical caisson are calculated for various parameters by considering the energy loss and the change of porosity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.172-178
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• 2021

In the ship repair market, interest in maintenance and repair is steadily increasing due to the reinforcement of prevention of environmental pollution caused by ships and the reinforcement of safety standards for ship structures. By reflecting this effect, the number of requests for repairs by foreign shipping companies increases to repair shipbuilders in the Southwest Sea. However, because most of the repair shipbuilders in the southwestern area are small and medium-sized companies, it is difficult to lead to the integrated synergy effect of the repair shipbuilding companies. Moreover, the infrastructure is not integrated; hence, using the infrastructure jointly is a challenge, which acts as an obstacle to the activation of the repair shipbuilding industry. Floating docks are indispensable to operating the repair shipbuilding business; in addition, most of them are operated through renovation/repair after importing aging caisson docks from overseas. However, their service life is more than 30 years; additionally, there is no structure inspection standard. Therefore, it is vulnerable to the safety field. In this study, the finite element analysis program of ANSYS was used to evaluate the structural safety of the modified caisson dock and obtain additional structural reinforcement schemes to solve the derived problems. For the floating docks, there are classification regulations; however, concerning structural strength, the regulations are insufficient, and the applicability is inferior. These insufficient evaluation areas were supplemented through a detailed structural FE-analysis. The reinforcement plan was decided by reinforcing the pontoon deck and reinforcement of the side tank, considering the characteristics of the repair shipyard condition. The final plan was selected to reinforce the side wing tank through the structural analysis of the decision; in addition, the actual structure was fabricated to reflect the reinforcement plan. Our results can be used as reference data for improving the structural strength of similar facilities; we believe that the optimal solution can be found quickly if this method is used during renovation/repair.

• Journal of Welding and Joining
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• v.33 no.5
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• pp.9-13
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• 2015

Nickel alloy, especially Alloy 625, is used widely in industrial applications such as aerospace, chemical, petrochemical and marine applications due to their good mechanical properties, excellent fabricability, weldability and good corrosion resistance. Especially, it is obviously applied in FPSO's moon pool structure and caisson tubular of CPF under seawater environment. Recently, UNS S32654 was developed to substitute alloy 625 because of high cost price. In this study, mechanical properties and corrossive properties of UNS S32654 are reviewed and proposed its applications.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.614-617
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• 2006

This study investigates the quality control and the finishability improvement properties of durable marine concrete under construct in Geo-je Ka-duk fixed link project. Below $3.5\times10^{-12}m^2/s$ chloride migration coefficient and above 40MPa compressive strength are required for the caisson structure concrete. The quality control was performed from physical-chemical analysis of raw materials to concrete test. Also, the efficiency of vibration type and action interval were tested to remove the entrapped air on the faced to form. And kinds of form and remolding agent were also tested. This paper aim to enhance the practical use of high performance concrete to construction field.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.81.1-81
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• 2002

$\textbullet$ This paper presents a study on the development of a walking robot for an armor-stone work of the breakwater construction. The armor-stone work is putting stones about 0.3 ∼ 2m3 on the surface of the breakwater to prevent it from waving. $\textbullet$ This work has been done manually, and its process plan is uncertain by effects of the weather, wave and tide of sea. Therefore the constructional cost is considered to be wasteful $\textbullet$ Working in underwater as well as on land for human workers causes the accident and caisson disease, so it is necessary to replace the process to be mechanized. $\textbullet$ The basic requirements of the robot for mechanizing are as follows : 1) To have a large...

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.160.1-160.1
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• 2011

In this study, the influence of methodology of assessing water levels on the discharge coefficient of sluice for tidal power generation was investigated. A physical experiment was performed in a planar open channel by installing 1/70 scale model of the sluice caisson in the planar open channel. In front of and behind the sluice model, sloping bathymetry was made to reproduce corresponding field condition. By analyzing the experimental results, it was found that the location of measuring water levels significantly affects the estimates of the discharge coefficient, due to the variability of the parameter according to the head difference between the measuring locations. Therefore, it is necessary to be careful in estimating and utilizing the discharge coefficient in the relevant study of a tidal power generation.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1454-1458
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• 2004

본 인구에서는 직립 유공 케이슨에 현수판을 설치함으로서 입사파의 반사율을 저감시키고자 하였다. 먼저 케이슨 단면의 적정 유공율을 선정하기 위해 횡 SLIT 케이슨식 2개안 및 종 SLIT 1개안 단면에 대한 단면 실험을 실시하였다. 선행된 실험에서 가장 반사율이 낮은 SLIT 케이슨을 선택하여 유수실에 현수판을 설치 하였으며 현수판의 설치유무 및 현수판의 길이에 따른 반사계수를 검토하였다. 설치된 현수판은 장주기파에 대해서 반사율 저감효과를 얻을 수 없었지만 단주기 파에서는 반사율이 줄어드는 효과를 얻을 수 있었다. 해역에따라 단주기가 주류를 이루는 해역에서 현수판을 설치하면 파랑내습시 소파효과가 증대될 것으로 기대된다.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.1-9
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• 1993

Various geometric modeling techniques for a hull have been developed with wide application of computer to the ship design. Up to now, they are used for the representation of the sculptured surface with the piecewise polynominal curves or surfaces for a conventional hull. In this paper, a convenient and accurate modeling technique that is instancing and blending of the geometry primitives is introduced for a non-conventional hull such as SWATH, trimaran, caisson etc. Geometric characteristics, hydrostatic particulars and stability of the definded hull are calculated.