• Journal of Ocean Engineering and Technology
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• v.20 no.4 s.71
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• pp.9-16
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• 2006

A new wave-absorbing system, called the liquefied sandbed wave barrier (LSWB) system, is currently under development at the Port and Airport Research Institute (PARI) of Japan. The wave damping effect by the LSWB system is substantial, as confirmed by small-scale experiments and FEM numerical calculations, i.e., the wave transmission coefficient of the system is less than 0.2. Here, the results of large-scale experiments arediscussed in view of practical application. Although the LSWB system provides high wave damping, nearly equal to theoretical values, difficulty exists in obtaining a homogeneously liquefied sandbed, due to the occurrence of liquefied sandbed compaction by cyclic wave loading, which in turn, reduces excess pare pressure and the wave damping effect. These two phenomena primarily occur when the sandbed is composed of fine sand with small permeability. Based on experimental results, we propose a design method that includes countermeasures against such problems, and a prototype LSWB system is constructed in a very large wave flume at PARI. Wave damping by the prototype LSWB system is confirmed to be quite stable and high, as predicted by theoretical calculations.

• Journal of Navigation and Port Research
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• v.33 no.2
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• pp.119-125
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• 2009

The effect of plastic board drains (PBDs)on ground improvement was checked out considering three crucial factors: ground settlement, undrained shear strength, and residual water head. First, the settlement analysis including initial settlement induced by reclamation of sand mat was conducted by back calculation analysis with measured data. Its result showed toot the PBDs used for this site worked well on improving soft ground. Secondly, the undrained shear strength was investigated by laboratory and in-situ tests including unconsolidated-undrained triaxial compression (UU) tests, unconfined compression tests, in-situ vane tests, and cone penetration tests. From the test results, they showed that the undrained shear strength of the improved ground by PBDs was significantly increased as well as the strength increasing ratio especially $10{\sim}15m$ below the ground surface on site. Thirdly, the residual water head measurement from the in situ dissipation test was found the same as the static water head, which indicated primary consolidation was completed and the effect of soil improvement with PBDs can be confirmed.

• Journal of Navigation and Port Research
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• v.32 no.4
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• pp.315-320
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• 2008

The road construction near the existing lighter's wharf has completed but the lighter's wharf has been still unavailable and neglected. Therefore, the site needs the urgent measures to clean up and properly take advantage of the lighter's wharf. This study sought to improve the regional amenities and revitalize the coastal environment by creating an environment-friendly waterfront park utilizing features of the existing lighter's wharf as part of improvement measures. In addition, surveys were conducted to develop an waterfront park capable of effectively using the land and improving the cleanliness and safety of the coastal scenic beauty, leading to various meaningful opinions on the residents' awareness of the potential park site, the facilities necessary for the park, the development directions of the park and the timing of park development. If an waterfront park is created through the residents' participation, It can share a sustainable utility value of the coastal area. Therefore, this will result in boosting the connection with redevelopment plan for the North Port, along with improving the quality of the residents' life, strengthening Busan's status as a maritime tourism city.

• Journal of Navigation and Port Research
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• v.32 no.4
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• pp.305-313
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• 2008

Recently it was known that the problems of nearshore processes and damage of berth and counter facilities frequently had appeared at the small fishery port, such as Daebang near Samcheonpo city, Korea. Here we try to analyze the impact of the rearrangement of counter facilities and berth layout adopted for tranquility of its inner harbor. Because this harbor is being connected to Daebang channel, the rearrangement of the structures might affect to the current speed and direction and wave height, so do to the sea bottom undulation. Therefore, we made model test for the several layouts of the berth and breakwater in this area. Numerical model result shows that the bottom was eroded by 1m by tidal currents and the speed of flow did not shrink, even after the construction work was completed. The direction of the sand movement was downdrift. Although the model study gave reasonable description of beach processes and approach channel sedimentation mechanism, it is necessary to compare with the field history, including the records of waves, tides and bottom materials, etc. for better prediction.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.158-160
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• 2009

선행되었던 연구인 실린더 슬릿형 소파블록 방파제에 대하여 실해역에서의 적용성을 평가하기 위하여 수치모델 해석을 통해 항내정온도를 분석하였다. 남해의 소규모 어항에 대해 파랑작용 평형방정식을 이용하는 SWAN 모델을 구성하고 수리모형실험에서 분석된 실린더형 슬릿 방파제의 투과율과 반사율을 도입하여 항내의 정온도의 변화를 불투과성 방파제와 비교하여 다루고 해수교환을 통한 해역수질환경의 개선 가능성을 예측해보았다. 수치실험은 한국해양연구원의 전해역 심해설계파 추정 보고서 II(2005)중의 심해설계파 제원을 사용하였으며, 대상해역의 1970년$\sim$2006년(37년간) 관측된 연최대 풍속자료를 이용하여 산정된 50년빈도 설계풍을 모델에 반영하였다. 대상 어항에서 서방파제에 주로 영향을 미치는 NNE계열의 파랑의 내습에 대한 분석을 수행하였으며, 그 결과 투과성구조물의 특성이 수치모형에서도 잘 재현하고 있음을 파악하였다.

• Journal of architectural history
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• v.28 no.2
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• pp.7-18
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• 2019

The Chosun Dynasty established and implemented measures to prevent Japanese invasion into the southern coast. To this end, the number of naval vessels and the number of ships were increased, and a shipyard(船所) was constructed to protect the safety of the vessels. The shipyard is a port facility where military vessels are anchored and repaired, as well as public facilities that are needed for military training on public and land, as well as facilities for storing supplies and equipment needed for ships on land and defense at the port entrance. Despite being such an important facility for national defense, Shipyard has not been noticed. Studies have shown that the position of shipyard is divided into the riverside type and the riverbank type, which is due to the topographical features of Korea. The repair cycle of naval vessels, the carrying out of Yeonhun(prevent the water from decaying the part of the ship, a raw tree was burned to smoke) and the place of sea training also affected the construction of the Gul River(掘江). The space structure of shipyard is divided into port entry facilities for monitoring and controlling at the entrance to the harbor, border facilities for folding and repairing military vessels, and land facilities for holding land exercises and administrative work of military vessels and military equipment.

• Journal of Drive and Control
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• v.17 no.4
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• pp.46-53
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• 2020

In this paper, the development of a manually and continuously variable impact force control mechanism for hydraulic breakers was studied. Generally, a hydraulic breaker has one or two piston strokes. Hydraulic breakers, which have two strokes, have two valve-switching ports and make short and long piston strokes. The piston stroke valve controls the piston stroke by opening and closing a short stroke-switching port. The short piston stroke mode is used to break soft rock, concrete, or asphalt. This stroke control valve system is not popular for small hydraulic breakers mounted on 1 to 14-ton excavators. To preserve the carrier-like excavator, proper breaking force is needed, and it can be easily controlled by multiple piston stroke control valves. The easiest way to control these breakers is to use several switching ports and valves but they are not easy to install in small hydraulic breakers and are expensive. To use only one switching port and valve, a method can be used to change the open area of the switching port to delay valve switching. This method provides multiple piston strokes.

• Journal of architectural history
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• v.32 no.2
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• pp.49-62
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• 2023

This study was prepared for the purpose of restorative consideration such as the construction background, scale, and location of buildings by comparing the historical materials of two countries, Korea and Japan, focusing on Choryanggaeksa. Choryanggaeksa was a building with a special purpose installed in Dongnaebu in the late Joseon Dynasty, and was also a space exclusively for Japanese envoys. When Choryangwaegwan, the only place of diplomacy and trade with Japan in the late Joseon Dynasty, moved in 1678, Choryanggaeksa was also built and continued until its function ceased due to the modern opening of the port. As diplomacy and trade with Japan take place in the category of Choryangwaegwan, the existence of an interpreter takes an important place. Therefore, Seongsindang, a space for interpreters, was built near Choryanggaeksa. When the modern port opened in 1876, Choryanggaeksa and Seongsindang lost their original function, but the building remained. However, after the 1890s, a Superintendent office was built on the site of Choryanggaeksa, and a school was established on the site of Seongsindang. It was destroyed when the site of Choryanggaeksa and Seongsindang was converted during the opening of the port, and its remains cannot be found today due to urbanization.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.400-403
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• 2004

In conventional methods, the availability of floating crane has determined the size of a concrete caisson. However, this paper introduces a new method for larger caisson production that make it possible to complete caisson fabrication and launch out without use of floating crane. The new method carries out multi-step fabrication of caisson and horizontal transfer of caisson on a single casting bed which consists of collapsible soffit form, trough, aero go watercaster system or low frictional PTFE added jacking system, half-submergible floating dock. To make the new method successfully launched, the static and dynamic analysis is carried out to obtain the stability of caisson launching and experimental research is conducted in evaluating friction occurred between PTFE pad and steel track. Lastly, the comparison of the new method and the conventional method are detailed. With significant benefits in construction costs reduction and construction time reduction, this new method in this paper would be recommended for extensive application in large port and harbor construction projects.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1365-1369
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• 2008

A large diameter sampler (KICT-type large diameter sampler) was developed to take undisturbed samples from not only soft ground but also sandy and weathered ground. The KICT-type large diameter sampler was manufactured with the principle of triple core barrel sampling. In this study, the applicability to offshore ground sampling of the KICT-type large diameter sampler was confirmed at Inchoen Port construction site. And, in order to compare the quality of samples taken by the sampler with that of the traditional piston sampler, a series of laboratory tests were performed. From the test results, the samples taken by the KICT-type large diameter sampler showed higher quality than the traditional thin-walled tube samples.