• Water Engineering Research
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• 제1권2호
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• pp.159-168
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• 2000

In this paper, the increment of the local scour depth at piers by constructing the bridge between existing bridges is examined through the experiments in which 5 piers in the non-cohesive bed material in the experimental flume were installed. In the experiments the maximum distance of 25 times of the pier length and the maximum distortion width of 8 times of the pier width were utilized. Through the experimental studies, it was indicated that low flow, which can be characterized as the flow having low Froude numbers, the maximum bed configuration change is obtained when the piers are installed in the straight line in the flor direction without any distortion. However, In the high flow, which can be characterized as the flow having high Froude numbers, the maximum bed configuration change is obtained when the piers are installed with some distortion from the flow direction. The influence of the bed configuration by interaction between bridge piers is changed depending upon the Froude numbers, the distance between piers, and the distortion width between adjacent bridge piers. Also, because the scour patterns are affected by the bed configuration, the maximum scour should be increased by about 60% compared to that in a single pier if the interaction between bridge piers exists. It can be suggested that the maximum scour depth at bridge piers predicted by applying the existing equations should be increased if the interaction between bridge piers exist. Those cases are found when new bridges are constructed successively in the river in the urban area.

• Journal of Ship and Ocean Technology
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• 제8권2호
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• pp.29-40
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• 2004

Interaction of grounded ice ridges with underlying seabed is one of the major considerations in the design of Arctic pipeline system. Previously several ice scour models were developed by researchers to describe the ice scour-seabed interaction mechanism. In this paper, a parametric study on ice scouring mechanism is performed and the limitation of ice scour-seabed interaction models is discussed. Simple laboratory tests are carried out and then the shape pattern of deposited soil around the ice is redefined. New ice scour model assumes trapezoidal cross section based on the field observation data. Ice scour depth and soil resistance forces on seabed are calculated with varying the keel angle of a model ice ridge.

• Geomechanics and Engineering
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• 제20권5호
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• pp.421-432
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• 2020

Cutting of rocks is very common encountered in tunneling and mining during underground excavations. A deep understanding of rock-tool interaction can promote industrial applications significantly. In this paper, a distinct element method based approach, PFC^3D, is adopted to simulate the rock cutting under different operation conditions (cutting velocity, depth of cut and rake angle) and with various tool geometries (tip angle, tip wear and tip shape). Simulation results showed that the cutting force and accumulated number of cracks increase with increasing cutting velocity, cut depth, tip angle and pick abrasion. The number of cracks and cutting force decrease with increasing negative rake angle and increase with increasing positive rake angle. The numerical approach can offer a better insight into the rock-tool interaction during the rock cutting process. The proposed numerical method can be used to assess the rock cuttability, to estimate the cutting performance, and to design the cutter head.

• ETRI Journal
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• 제35권2호
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• pp.356-359
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• 2013

We present a method for tracking and interaction based on hybrid sensing for virtual environments. The proposed method is applied to motion tracking of whole areas, including the user's occlusion space, for a high-precision interaction. For real-time motion tracking surrounding a user, we estimate each joint position in the human body using a combination of a depth sensor and a wand-type physical user interface, which is necessary to convert gyroscope and acceleration values into positional data. Additionally, we construct virtual contents and evaluate the validity of results related to hybrid sensing-based whole-body tracking of human motion methods used to compensate for the occluded areas.

• Earthquakes and Structures
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• 제18권4호
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• pp.407-421
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• 2020

In-place analysis for offshore platforms is essentially required to make proper design for new structures and true assessment for existing structures, in addition to the structural integrity of platforms components under the maximum and minimum operating loads when subjected to the environmental conditions. In-place analysis have been executed to check that the structural member with all appurtenance's robustness have the capability to support the applied loads in either storm or operating conditions. A nonlinear finite element analysis is adopted for the platform structure above the seabed and pile-soil interaction to estimate the in-place behavior of a typical fixed offshore platform. The SACS software is utilized to calculate the dynamic characteristics of the platform model and the response of platform joints then the stresses at selected members, as well as their nodal displacements. The directions of environmental loads and water depth variations have significant effects in the results of the in-place analysis behavior. The most of bending moment responses of the piles are in the first fourth of pile penetration depth from pile head level. The axial deformations of piles in all load combinations cases of all piles are inversely proportional with penetration depth. The largest values of axial soil reaction are shown at the pile tips levels (the maximum penetration level). The most of lateral soil reactions resultant are in the first third of pile penetration depth from pile head level and approximately vanished after that penetration. The influence of the soil-structure interaction on the response of the jacket foundation predicts that the flexible foundation model is necessary to estimate the force responses demands of the offshore platform with a piled jacket-support structure well.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2013년도 춘계학술대회
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• pp.15-16
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• 2013

This paper is mainly concerned with the ship-bank interaction by model test. The experiments for the characteristics of hydrodynamic interaction forces and moments between vessel and bank with a mound were carried out in the seakeeping and maneuvering basin.

• Wind and Structures
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• 제21권6호
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• pp.625-639
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• 2015

Monopiles have been most widely used for supporting offshore wind turbines (OWTs) in shallow water areas. However, multi-member lattice-type structures such as jackets and tripods are also considered good alternatives to monopile foundations for relatively deep water areas with depth ranging from 25-50 m owing to their technical and economic feasibility. Moreover, jacket structures have been popular in the oil and gas industry for a long time. However, several unsolved technical issues still persist in the utilization of multi-member lattice-type supporting structures for OWTs; these problems include pile-soil-interaction (PSI) effects, realization of dynamically stable designs to avoid resonances, and quick and safe installation in remote areas. In this study, the effects of PSI on the dynamic properties of bottom-fixed OWTs, including monopile-, tripod- and jacket-supported OWTs, were investigated intensively. The tower and substructure were modeled using conventional beam elements with added mass, and pile foundations were modeled with beam and nonlinear spring elements. The effects of PSI on the dynamic properties of the structure were evaluated using Monte Carlo simulation considering the load amplitude, scouring depth, and the uncertainties in soil properties.

• 한국해양공학회지
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• 제33권6호
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• pp.556-563
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• 2019

The ice keel gouge and seabed interaction is one of the major considerations in the design of an Arctic pipeline system. Ice keel and seabed interaction engineering models based on experimental data, which give an explicit equation for estimating the ice gouging depth, have been suggested. The suggested equations usually overestimate the ice keel gouging depth. In addition, various types of numerical analyses have been carried out to verify the suggested engineering model equations in comparison to the experimental data. However, most of numerical analysis results were also overestimated compared with the laboratory experimental data. In this study, a numerical analysis considering the contact condition and geostatic stress was carried out to predict the ice keel gouging depth and compared with the previous studies. Considering the previously mentioned conditions, more accurate results were produced compared with the laboratory experiment results and the error rate was reduced compared to previous numerical analysis studies.

• 한국멀티미디어학회논문지
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• 제15권4호
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• pp.501-507
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• 2012

Human body motion is a non-verbal part for interaction or movement that can be used to involves real world and virtual world. In this paper, we explain a study on natural user interface (NUI) in human hand motion recognition using RGB color information and depth information by Kinect camera from Microsoft Corporation. To achieve the goal, hand tracking and gesture recognition have no major dependencies of the work environment, lighting or users' skin color, libraries of particular use for natural interaction and Kinect device, which serves to provide RGB images of the environment and the depth map of the scene were used. An improved Camshift tracking algorithm is used to tracking hand motion, the experimental results show out it has better performance than Camshift algorithm, and it has higher stability and accuracy as well.

• 한국방사선학회논문지
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• 제17권1호
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• pp.11-16
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• 2023

전임상용 양전자방출단층촬영기기는 관심 시야 외곽에서의 공간분해능 저하현상이 발생한다. 이를 해결하기 위해 감마선과 섬광체가 상호작용한 위치를 측정하는 반응 깊이 측정(depth of interaction, DOI) 검출기가 개발되었다. 여러 층으로 섬광 픽셀 배열을 구성한 방법, 하나의 층의 양단에 광센서를 배치한 방법, 여러 층으로 섬광 픽셀 배열을 구성하고 각 층마다 광센서를 배치한 방법 등이 있다. 본 연구에서는 기존에 개발된 검출기들의 특징을 분석하여 새로운 형태의 DOI 검출기를 설계하였다. 두층으로 구성된 검출기는 각 층마다 서로 다른 크기의 섬광 픽셀을 사용하여, 배열의 크기를 다르게 구성하였다. 이러한 형태로 구성할 경우 층별 섬광 픽셀의 위치는 서로 어긋나게 배열되어 평면 영상에서 서로 다른 위치에 영상화된다. 설계한 검출기의 반응 깊이 측정 가능성을 확인하기위해 DETECT2000 시뮬레이션을 수행하였다. 각 섬광 픽셀의 중심에서 발생된 감마선 이벤트로 획득한 빛의 신호로 평면 영상을 재구성하였다. 그 결과 각 층별 모든 섬광 픽셀이 재구성된 평면 영상에서 분리되어 영상화되어, 반응 깊이를 측정할 수 있음을 확인할 수 있었다. 본 검출기를 전임상용 PET에 적용할 경우 공간분해능의 향상을 이루어 우수한 영상을 획득할 수 있을 것으로 사료된다.