• 산업기술연구
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• 제29권B호
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• pp.65-72
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• 2009

In this paper centrifuge model tests and numerical analysis on the coastal structure on the marine deposits of sand were performed to investigate the behavior of structure and foundation under the condition of wave action in field. In centrifuge model experiments, construction sequence of coastal structure such as preparation of sand deposit, excavation replacement, rubble mound with crushed stones and installment of coastal structure was reconstructed and the behavior of ground settlement during stage of construction was observed during tests. For the final stage of simulating the horizontal movement of coastal structure due to wave force, horizontal load was applied by horizontal loading apparatus being specially designed so that horizontal displacement of structure could be observed. Numerical analysis were also carried out and its results were compared with test results to assess the property of centrifuge mode experiments with respect to the behavior of structure as well as ground.

• 한국항해학회지
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• 제13권1호
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• pp.77-106
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• 1989

Two numerical models of the shoreline change and sediment transport rates, explicit and implicit, are simulated with shore structures such as breakwaters, a jetty, groins and a seawall. The applied study area is songdo Beach, Youngil bay, Korea since it has all the shore structures mentinoed above. The two models investigate the beach line changes and sedimen transport rates for the beach before design of three groins with and without an offshore breakwater. In order to estimate the shoreline changes after three groins were built, the beach response inside the three groin compartiments and the offshore barrier are also investigated. The simulation based on the initial shoreline conditions surveyed by the Hydrographic office, Koreai 1979 and 1984. The breaking wave characteristics are introduced into the models by calculation from the empirical equations and modification from the numerical and hydraulic model test results developed for waves behind an offshore breakwater. The numerical simulation describes well the tendencies of the sand transport and shoreline changes affected by wave diffraction behind a detached breakwater and by interruption of sand transport at three groins.

• 한국지구과학회지
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• 제44권4호
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• pp.264-274
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• 2023

The Korea Strait comprises a continental shelf in a shallow sea that experienced glacio-eustastic sea-level changes during the Quaternary period. A long core of 76.6 m in length was acquired at the South Sea Drilling Project site (SSDP-101; 34°19.666'E and 128°16.335'N) with a 60 m water deep. The uppermost massive sand beds were interpreted as sandy sediments of the nearshore marine sand ridge in the shallow sea during the transgression of sea level, whereas the lower parts of alternating sandy and muddy beds were interpreted as deposits in marsh, estuary, and tidal flat environments. A three-layered geoacoustic model was reconstructed for the sedimentary succession in the high-resolution seismic profile based on a 140-grain size and sediment type of core SSDP-101. For the actual underwater simulation and experiments, the in-situ P-wave speeds were calculated using the sound speed ratio of the Hamilton method.

• 한국해양학회지
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• 제27권1호
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• pp.66-77
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• 1992

태안반도 외해역에서 고해상용 천부지층 기록지상에 나타나는 조류성사퇴들 및 sand waves 발달 특징과 표층 퇴적물의 특성 결과를 조류 분포와 관련하여 사질 퇴적 물의 이동양상을 추정하였다. 조사해역에는 비대칭형 사퇴들이 북동-남서방향이 우세 한 강한 조류방향과 평행하거나 반시계방향으로 약간 빗겨지면서 길게 발달하고 있으 며 대부분의 사퇴들은 남 내지 남동쪽으로 급사면을 가지며 대략 남쪽방향으로 사층리 구조가 발달하고 있는 특징을 가진다. 현세 퇴적층은 사퇴들의 퇴적층 두께와 발달 양 상을 보여주며 분포한다. 이 결과로부터 현세 활동성사퇴들은 남동, 남 그리고 남서쪽 방향의 외해를 향해 퇴적물을 전적으로 이동시키는 것으로 해석된다. 동쪽 내지 북동 쪽의 급사면을 갖는 비대칭형 sand waves 가 수심 약 40-60 m를 보이는 일부 지역의 평탄한 해저면에 발달 분포한다. Sand waves 가 발달한 지역의 표층 퇴적물은 세립사 질 퇴적물로서 분급도가 매우 양호하게 나타나며 이들 지역의 사질 퇴적물은 동쪽 내 지 북동쪽 육지를 향해 이동되는 것으로 사료된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1976년도 제7차 하계학술발표회 및 산학협동세미나초록
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• pp.49-52
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• 1976

• 한국건설순환자원학회논문집
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• 제2권2호
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• pp.93-100
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• 2006

Building materials are trending toward environmental materials nowadays and the market share of those is growing. So those researches and developments for environmental property are proceeding now. The main properties of environmental products are far infrared emission, negative ion emission, electro magnetic wave shielding, and anti fungus, these products are used with shape of mortar, and spray on the finish material. But There are not much researches for the concrete, main material in construction field, with those functional properties. So in this research we evaluated slump, compressive strength and air content as basic properties for concrete using functional materials of sericite, wood pattern sand stone, carbon black and nanometric silver solution and functional properties like far infrared emission, negative ion emission, electro magnetic wave shielding, and anti fungus. The results were as follows. The most useful material in the functional materials was carbon black. Sericite and nanometric silver solution had a little effect on functional property, so it was difficult to apply to concrete, and wood pattern sand stone had a high functional property but low compressive strength, can be applied to a factory product. Anti fungus of the concrete using nanometric silver solution was not clear but if those specimens were aged in $CO_2$ gas for a long time it might apparent.

• 한국해양공학회지
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• 제20권4호
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• pp.43-49
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• 2006

Detailed investigations were carried out on the stability of the dredged soil bed against wave actions, aimedat establishing the design method of artificial tidal flats using dredged soil. The soil was dredged at Nagoya port, Japan, and has a mean grain size of 0.013mm. Basic features of artificial dredged soil bed against wave actions were explained from a series of model experiments in a wave flume. The two types of section shapes were employed; one is a horizontal bed and the other is a sloped one. Changes of the bed profile, shear strength, grain size distribution and water content, according to the wave actions, were measured in detail. The cumulative effect of the wave actions, over about one week, was investigated. A dredged soil bed moves withthe wave actions with relatively small wave height. It should be especially. noted that the clay component is dissolved and flown out, away from the surface layer, and consequently the surface layer hardens, as if it is covered with sand. Wren the wave height is gradually increased, the bed is not liquefied and the shear strength of the dredged bed is increased by a wave-induced dissipation of pore pressures in the bed and a decrease of clay component by the wave-induced leakage.

• 한국해양공학회지
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• 제20권4호
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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.

• 한국지반공학회논문집
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• 제36권9호
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• pp.21-32
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• 2020

본 연구에서는 포항 액상화 현상 발생 현장에서 채취한 모래를 사용하여 진동삼축시험 및 전단파 속도 측정을 수행하였으며, 시험결과를 기반으로 액상화 저항곡선을 도출하여 액상화 저항강도(CRR)를 산정하였다. 전단파 속도는 지진 발생 전 현장상태를 모사하고자 압밀 단계 종료 시점에서 측정한 값을 활용하였다. 시험을 통해 액상화 저항강도에 대한 두 가지 인자(입도분포, 상대밀도)의 영향을 확인하였으며 기존 문헌에서 제시된 타 사질토의 액상화 저항강도와의 비교를 통해 포항 모래의 액상화 저항강도를 정량적으로 평가하였다. 또한, 측정한 전단파 속도를 활용하여 실제 현장에서 사용되는 액상화 평가 곡선과의 비교를 통해 시험 결과의 신뢰성을 확인하였다.

• 대한토목학회논문집
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• 제31권5B호
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• pp.483-489
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• 2011

본 연구에서는 잠제 주변의 세굴 및 퇴적현상을 수치적으로 모의하기 위해 기존의 수치 파동 모델에 모래입자의 거동 해석을 위한 lagrangian 입자 모델을 결합한 새로운 수치모델을 개발하였다. 수치 파동 모델로서는 파랑에 의한 해저지반 내의 모래입자의 이동과 유동화 해석을 위해 투수성 매체 내부의 유체저항(관성저항, 층류저항 및 난류저항)을 고려할 수 있는 수치모델에 LES 난류모델을 도입한 수치해석기법(허와 최, 2008)을 이용하였다. 또한, 모래입자의 이동해석을 위한 lagrangian 입자 모델로서는 많은 개개의 입자들의 동적해석에 탁월한 개별요소법(Cundall and Strack, 1979)을 적용하였다. 개발된 해석기법을 이용하여 불투과 잠제 전면의 세굴에 대한 수치시뮬레이션을 실시한 후, 기존의 수리모형실험과 정성적으로 비교하면서 그 적용성을 검토하였다.