• Structural Engineering and Mechanics
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• v.46 no.4
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• pp.487-504
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• 2013

In the present work a new friction device, with a set of single or double rotational friction flanges and a link element, is described and tested. The mechanism may be applied for the strengthening of existing r/c or steel buildings as well as in new constructed buildings. The device has selectable variable behavior in different levels of displacement and an interlock mechanism that is provided by the link element. The link element may be designed to lock at preselected level of displacement, offering in this way an extra safety reserve against strong earthquakes. A summary of the existing literature about other similar mechanisms is initially presented in this paper. The proposed mechanism is presented and described in details. Laboratory experiments are presented in detail and the resulted response that proves the efficiency of the mechanism at selectable levels of strength capacity is discussed. Drawings of the mechanism attached to a r/c frame with connection details are also included. Finally a dynamic analysis of two r/c frames, with and without the proposed mechanism attached, is performed and the resulted response is given. The main conclusion is that the proposed mechanism is a cheap and efficient devise for the improvement of the performance of new or existing framed buildings to seismic loads.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.23-30
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• 2001

The cavitation noise of high-speed propellers was experimentally studied using new measurement device in KRISO cavitation tunnel. A series of cavitation noise tests were carried out for 6 propellers with various sections, loading distributions, and a different area ratio. From the experimental results, the noise characteristics for various cavitation patterns and the noise performance for a series of propellers were analyzed. These can be used for full-scale prediction study of the noise and optimum design of high-speed propellers.

• Steel and Composite Structures
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• v.25 no.2
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• pp.245-255
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• 2017

The performance of an Industrialised Building System (IBS) consists of prefabricated reinforced concrete components, is greatly affected by the behaviour of the connection between beam and columns. The structural characteristics parameters of a beam-to-column connection like rotational stiffness, strength and ductility can be explained by load-rotation relationship of a full scale H-subframe under gravitational load. Furthermore, the connection's degree of rigidity directly influences the behaviour of the whole frame. In this research, rotational behaviour of a patented innovative beam-to-column connection with unique benefits like easy installation, no wet work, no welding work at assembly site, using a hybrid behaviour of steel and concrete, easy replacement ability, and compatibility with architecture was investigated. The proposed IBS beam-to-column connection includes precast concrete components with embedded steel end connectors. Two full-scale H-subframes constructed with a new IBS and conventional cast in-situ reinforced concrete system beam-to-column connections were tested under incremental static loading. In this paper, load-rotation relationship and ratio of the rigidity of IBS beam-to-column connection are studied and compared with conventional monolithic reinforced concrete connection. It is concluded that this new IBS beam-to-column connection benefits from more rotational ductility than the conventional reinforced concrete connection. Furthermore, the semi-rigid IBS connection rigidity ratio is about 44% of a full rigid connection.

• Annual Conference of KIPS
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• 2012.04a
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• pp.29-32
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• 2012

전통적으로 컴퓨터의 성능은 중앙 연산 장치 (CPU)의 성능에 따라 좌지우지 되어 왔다. 하지만 CPU의 성능이 지속적인 발전을 거듭하여 무어의 법칙을 비교적 충실히 따라가고 있는 반면, 메모리의 성능은 근래 들어 더디게 발전되는 형국이다. 때문에, CPU와 메모리 간의 성능격차로 인해 메모리의 낮은 성능이 전체 시스템의 성능을 저하시키는 "Memory Wall Problem"은 점점 큰 문제로 대두되고 있다. 이러한 문제를 해결하기 위해 많은 연구에서 메모리 자체의 성능을 발전시키는 것은 물론 메모리 내부에 연산 처리 능력을 추가하여 시스템 전체의 성능을 향상 시키는 시도들을 해왔다. 이 논문에서는 이러한 Intelligent한 메모리 시스템에서의 SW Off-loading을 위한 성능 분석을 다룬다. 이전의 연구들이 주로 큰 단위의 Off-load를 다뤘던 것에 비해 이 논문에서는 작은 단위의 Off-load, 더 정확히는 어셈블리 수준의 Off-load의 효과에 대해 분석한다. 또한 현재의 어셈블리 수준의 Off-load의 한계를 지적하고 이를 극복하기 위한 루프 레벨 Off-load, 새로운 Technology와 아키텍쳐에 대해서도 소개한다.

• International journal of advanced smart convergence
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• v.10 no.4
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• pp.110-116
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• 2021

This paper proposed a real-time earlobe detection system using deep learning on the web. Existing deep learning-based detection methods often find independent objects such as cars, mugs, cats, and people. We proposed a way to receive an image through the camera of the user device in a web environment and detect the earlobe on the server. First, we took a picture of the user's face with the user's device camera on the web so that the user's ears were visible. After that, we sent the photographed user's face to the server to find the earlobe. Based on the detected results, we printed an earring model on the user's earlobe on the web. We trained an existing YOLO v5 model using a dataset of about 200 that created a bounding box on the earlobe. We estimated the position of the earlobe through a trained deep learning model. Through this process, we proposed a real-time earlobe detection system on the web. The proposed method showed the performance of detecting earlobes in real-time and loading 3D models from the web in real-time.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2709-2716
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• 2020

Compositions of large nuclear cores (e.g. boiling water reactors) are highly heterogeneous in terms of fuel composition, control rod insertions and flow regimes. For this reason, they usually lack high order of symmetry (e.g. 1/4, 1/8) making it difficult to estimate their neutronic parameters for large spaces of possible loading patterns. A detailed hyperparameter optimization technique (a combination of manual and Gaussian process search) is used to train and optimize deep neural networks for the prediction of three neutronic parameters for the Ringhals-1 BWR unit: power peaking factors (PPF), control rod bank level, and cycle length. Simulation data is generated based on half-symmetry using PARCS core simulator by shuffling a total of 196 assemblies. The results demonstrate a promising performance by the deep networks as acceptable mean absolute error values are found for the global maximum PPF (~0.2) and for the radially and axially averaged PPF (~0.05). The mean difference between targets and predictions for the control rod level is about 5% insertion depth. Lastly, cycle length labels are predicted with 82% accuracy. The results also demonstrate that 10,000 samples are adequate to capture about 80% of the high-dimensional space, with minor improvements found for larger number of samples. The promising findings of this work prove the ability of deep neural networks to resolve high dimensionality issues of large cores in the nuclear area.

• Earthquakes and Structures
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• v.16 no.3
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• pp.279-293
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• 2019

The overall seismic performance of existing pre 1960-70s reinforced concrete (RC) structures is significantly affected by the inadequate length of columns' lap-spliced reinforcement. Due to this crucial structural deficiency, the cyclic response is dominated by premature bond - slip failure, strength and stiffness degradation, poor energy dissipation capacity and low ductility. Recent earthquakes worldwide highlighted the importance of improving the load transfer mechanism between lap-spliced bars, while it was clearly demonstrated that the failure of lap splices may result in a devastating effect on structural integrity. Extensive experimental and analytical research was carried out herein, to evaluate the effectiveness and reliability of strengthening techniques applied to RC columns with lap-spliced reinforcement and also accurately predict the columns' response during an earthquake. Ten large scale cantilever column subassemblages, representative of columns found in existing pre 1970s RC structures, were constructed and strengthened by steel or RC jacketing. The enhanced specimens were imposed to earthquake-type loading and their lateral response was evaluated with respect to the hysteresis of two original and two control subassemblages. The main variables examined were the lap splice length, the steel jacket width and the amount of additional confinement offered by the jackets. Moreover, an analytical formulation proposed by Tsonos (2007a, 2019) was modified appropriately and applied to the lap splice region, to calculate shear stress developed in the concrete and predict if yielding of reinforcement is achieved. The accuracy of the analytical method was checked against experimental results from both the literature and the experimental work included herein.

• Journal of Drive and Control
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• v.16 no.3
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• pp.1-7
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• 2019

The reach truck, which is mainly used in warehouses, is required to have high-mast to improve its working efficiency and space utilization. The high-mast takes advantage of more vertical space but severe vibrations are easily generated at the end of the high-mast. These vibrations may cause a collision or misplacement of loading location at work. In this study, the vibration characteristics of a three-stage high-mast of a reach truck are analyzed, and an active vibration controller verified through a similar experiment is designed to reduce this vibration. A similar experiment for reach truck mast verifies the performance of the active vibration controller. By applying an active vibration controller designed for a real reach truck, the operations of the reach truck are made more efficient through the reduction of the vibration amplitude.

• Composites Research
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• v.32 no.2
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• pp.108-112
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• 2019

There has been a continuous study on the weight reduction of structure by composites. Unlike isotropic materials, the physical properties of composites vary according to the direction of laminate and the order of lamination. Therefore, in the case of composite ladders, it is essential to perform structural analysis to verify the planned design. In this study, ladder was designed by applying fabric material. In addition, the effect of loading position on the ladder was analyzed through finite element analysis, and structural performance was analyzed by selecting the most problematic location. We analyzed the effect of stacking order on the structural strength of the ladder by analyzing the structure by applying various stacking sequence and measuring the failure value in each layer.

• Earthquakes and Structures
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• v.16 no.3
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• pp.369-373
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• 2019

Construction industry is one of the largest markets for composite materials. Composite materials are mostly utilized as surface coatings or concrete reinforcements, and they can hardly be found as a load bearing member in buildings. The three-dimensional composite structures with considerable bending, compressive and shear strengths are capable to be used as construction load bearing members. However, these composites cannot compete with other materials due to higher manufacturing costs. If the cost issue is resolved or their excellent performance is taken into consideration to overcome disadvantages related to economic-competitive challenges, these 3D composites can significantly reduce the construction time and result in lighter and safer buildings. Sandwich composite panels reinforced with 3D woven glass fabrics are amongst composites with highest bending strength. The current study investigates the possibility of utilizing these composite materials to construct ceilings and their application as slabs. One-to-one scale experimental loading of these composite panels shows a remarkable bending strength. Simulation results using ABAQUS software, also indicate that theoretical predictions of bending behavior of these panels are in good agreement with the observed experimental results.