• Geomechanics and Engineering
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• v.9 no.6
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• pp.757-774
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• 2015

Reinforcing soils with the geosynthetics have been shown to be an effective method for improving the uplift capacity of granular soils. The pull-out resistance of the reinforcing elements is one of the most notable factors in increasing the uplift capacity. In this paper, a new reinforcing element including the elements (anchors) attached to the ordinary geogrid for increasing the pull-out resistance of the reinforcement, is used. Thus, the reinforcement consists of the geogrid and anchors with the cylindrical plastic elements attached to it, namely grid-anchors. A three-dimensional numerical study, employing the commercial finite difference software FLAC-3D, was performed to investigate the uplift capacity of the pipelines buried in sand reinforced with this system. The models were used to investigate the effect of the pipe diameter, burial depth, soil density, number of the reinforcement layers, width of the reinforcement layer, and the stiffness of geogrid and anchors on the uplift resistance of the sandy soils. The outcomes reveal that, due to a developed longer failure surface, inclusion of grid-anchor system in a soil deposit outstandingly increases the uplift capacity. Compared to the multilayer reinforcement, the single layer reinforcement was more effective in enhancing the uplift capacity. Moreover, the efficiency of the reinforcement layer inclusion for uplift resistance in loose sand is higher than dense sand. Besides, the efficiency of reinforcement layer inclusion for uplift resistance in lower embedment ratios is higher. In addition, by increasing the pipe diameter, the efficiency of the reinforcement layer inclusion will be lower. Results demonstrate that, for the pipes with an outer diameter of 50 mm, the grid-anchor system of reinforcing can increase the uplift capacity 2.18 times greater than that for an ordinary geogrid and 3.20 times greater than that for non-reinforced sand.

• Geomechanics and Engineering
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• v.33 no.6
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• pp.583-596
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• 2023

The interlayers, either softer or stiffer than the surrounding layers, are usually overlooked during field investigation due to the small thickness. They may be neglected through the analysis process for simplicity. However, they may significantly affect the dynamic behavior of the soil-foundation system. In this study, a series of 3D finite-element Direct-solution steady-state harmonic analyses were carried out using ABAQUS/CAE software to investigate the impacts of interlayers on the dynamic response of a cast in place pile group subjected to horizontal harmonic load. The experimental data of a 3×2 pile group testing was used to verify the numerical modeling. The effects of thickness, depth, and shear modulus of the interlayers on the dynamic response of the pile group are investigated. The simulations were conducted on both stiff and soft soils. It was found that the soft interlayers affect the frequency-amplitude curve of the system only in frequencies higher than 70% of the resonant frequency of the base soil. While, the effect of stiff interlayer in soft base soil started at frequency of 35% of the resonant frequency of the base soil. Also, it was observed that a shallow stiff interlayer increased the resonant amplitude by 11%, while a deep one only increased the resonant frequency by 7%. Moreover, a shallow soft interlayer increased the resonant frequency by 20% in soft base soils, whereas, it had an effect as low as 6% on resonant amplitude. Also, the results showed that deep soft interlayers increased the resonant amplitude by 17 to 20% in both soft and stiff base soils due to a reduction in lateral support of the piles. In the cases of deep thick, soft interlayers, the resonant frequency reduced significantly, i.e., 16 to 20%. It was found that the stiff interlayers were most effective on the amplitude and frequency of the pile group.

• International Journal of Computer Science & Network Security
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• v.24 no.2
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• pp.53-58
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• 2024

This paper presents a novel miniaturized 3-D cubic antenna for use in wireless sensor network (WSN) application. The geometry of this antenna is designed as a cube including a meander dipole antenna. A truly omnidirectional pattern is produced by this antenna in both E-plane and H-plane, which allows for non-intermittent communication that is orientation independent. The operating frequency lies in the ISM band (centered in 2.45 GHz). The dimensions of this ultra-compact cubic antenna are 1.25*1.12*1cm3 which features a length dimension λ/11. The coefficient which presents the overall antenna structure is Ka=0.44. The cubic shape of the antenna is allowing for smart packaging, as sensor equipment may be easily integrated into the cube hallow interior. The major constraint of WSN is the energy consumption. The power consumption of radio communication unit is relatively high. So it is necessary to design an antenna which improves the energy efficiency. The parameters considered in this work are the resonant frequency, return loss, efficiency, bandwidth, radiation pattern, gain and the electromagnetic field of the proposed antenna. The specificity of this geometry is that its size is relatively small with an excellent gain and efficiency compared to previously structures (reported in the literature). All results of the simulations were performed by CST Microwave Studio simulation software and validated with HFSS. We used Advanced Design System (ADS) to validate the equivalent scheme of our conception. Input here the part of summary.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.115-118
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• 2004

Respiratory motion in the thorax and abdomen is an important limiting factor in high-precision radiation therapy. The lung tumor and tumor(pancreas, stomach) in abdomen therefore are internal motion due to breathing. We will perform to measurement of dose distributions for these moving tumors. In preliminary study, we investigated displacement of moving tumor such as liver, lung tumor in abdomen with previously reported papers. With reference data, internal movements of tumor are displayed with phantom and moving control device(MCD), which appear three dimension (3-D) motion such as x, y and z axis. These devices are used to access dose delivered in tumor with and without internal motion. The MCD and phantom were used to evaluate a delivered dose under similar condition, although there are not same internal tumor motion. In future, we will obtain the exact evaluation of dose if improved in programed software of moving control device and measure precise internal motion using image modality such as fluoroscopy, simulator in based on this study.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.74-84
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• 2005

This paper include the investigation of finding the system characteristics of facility by simulating open-type turbo-pump fed system, which has commercial control valves, using AMESIM (Advanced Modeling Environment Simulation) commercial software. After developing a flight-type control valve on the basis of the results, the system characteristics of facility for control and valve tests is estimated. Especially, one of purposes of this paper is to find PID value of each commercial control valve in the facility for system test. To find suitable control logic, PI and PID modes are also compared. This paper also introduces design parameters of valve and equipment for thrust control and TDS simulation, which are using control valves.

• Journal of Information Processing Systems
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• v.16 no.3
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• pp.612-628
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• 2020

This paper presents a new approach for detecting abnormal behaviors in complex surveillance scenes where anomalies are subtle and difficult to distinguish due to the intricate correlations among multiple objects' behaviors. Specifically, a cascaded probabilistic topic model was put forward for learning the spatial context of local behavior and the temporal context of global behavior in two different stages. In the first stage of topic modeling, unlike the existing approaches using either optical flows or complete trajectories, spatio-temporal correlations between the trajectory fragments in video clips were modeled by the latent Dirichlet allocation (LDA) topic model based on Markov random fields to obtain the spatial context of local behavior in each video clip. The local behavior topic categories were then obtained by exploiting the spectral clustering algorithm. Based on the construction of a dictionary through the process of local behavior topic clustering, the second phase of the LDA topic model learns the correlations of global behaviors and temporal context. In particular, an abnormal behavior recognition method was developed based on the learned spatio-temporal context of behaviors. The specific identification method adopts a top-down strategy and consists of two stages: anomaly recognition of video clip and anomalous behavior recognition within each video clip. Evaluation was performed using the validity of spatio-temporal context learning for local behavior topics and abnormal behavior recognition. Furthermore, the performance of the proposed approach in abnormal behavior recognition improved effectively and significantly in complex surveillance scenes.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.4
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• pp.275-284
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• 2008

Purpose: We intended to evaluate myocardial oxygen consumption ($MVO_2)$ by applying recirculation correction and modified one-compartment model to have a reference range of $MVO_2$ in normal young population and to reveal the effect of recirculation on time-activity curve (TAC). Materials and Methods: In nine normal male volunteers with mean age of $26.3{\pm}4.0$, $MVO_2$ was estimated with 925 MBq (25mCi) of $^{11}C$-Acetate (Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea) and PET/CT (Biograph 6, Siemens Medical Solution, Germany). Analysis software such as $MATLAB^{(R)}$ v7.1 (Mathworks, Inc., United States), $Excel^{(R)}$ 2007 (Microsoft, United States), and $SPSS^{(R)}$ v12.0 (Apache Software Foundation, United States) were used. Twenty three frames were of $12{\times}10$, $5{\times}60$, $3{\times}120$, $2{\times}300's$ duration, respectively. The modified one-compartmental model and the recirculation correction method were applied. Statistical analysis was performed by using Test of Normality, ANOVA and Post-Hoc (Scheffe's) analysis, and p-value less than 0.05 was considered as significant. Results: The normal reference ranges of $MVO_2$ were presented as $3.18-4.64\;{\times}\;10^{-4}\;ml/g/sec$, $1.91-3.94\;{\times}\;10^{-4}\;ml/g/sec$, $4.31-6.40\;{\times}\;10^{-4}\;ml/g/sec$, $2.84-4.53\;{\times}\;10^{-4}\;ml/g/sec$ and $3.42-5.00\;{\times}\;10^{-4}\;ml/g/sec$ in the septum, the inferior wall, the lateral wall, the anterior wall and the entire wall, respectively. In addition, it was noted that the dual exponentiality of the clearance curve is due to the recirculation effect and that the characteristic of the curve is essentially mono-exponential. Conclusion: $^{11}C$-Acetate is a radiotracer worthwhile to assess $MVO_2$. Re-circulated $^{11}C$ can influence TAC of $^{11}C$ in myocadia and so the recirculation correction must be considered when measuring $MVO_2$.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.813-823
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• 2020

Purpose: In order to maximize the stability and productivity of the work through simulation prior to high-risk facilities and high-cost work such as dismantling the facilities inside the reactor, we intend to use digital twin technology that can be closely controlled by simulating the specifications of the actual control equipment. Motion control errors, which can be caused by the time gap between precision control equipment and simulation in applying digital twin technology, can cause hazards such as collisions between hazardous facilities and control equipment. In order to eliminate and control these situations, prior research is needed. Method: Unity 3D is currently the most popular engine used to develop simulations. However, there are control errors that can be caused by time correction within Unity 3D engines. The error is expected in many environments and may vary depending on the development environment, such as system specifications. To demonstrate this, we develop crash simulations using Unity 3D engines, which conduct collision experiments under various conditions, organize and analyze the resulting results, and derive tolerances for precision control equipment based on them. Result: In experiments with collision experiment simulation, the time correction in 1/1000 seconds of an engine internal function call results in a unit-hour distance error in the movement control of the collision objects and the distance error is proportional to the velocity of the collision. Conclusion: Remote decomposition simulators using digital twin technology are considered to require limitations of the speed of movement according to the required precision of the precision control devices in the hardware and software environment and manual control. In addition, the size of modeling data such as system development environment, hardware specifications and simulations imitated control equipment and facilities must also be taken into account, available and acceptable errors of operational control equipment and the speed required of work.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.168-178
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• 2017

In order to prevent major and chemical accidents, some of the plants which would like to install and operate hazard chemicals handling facilities must submit Off-site Consequence Analysis due to recent arisen leak accidents since 2015. A lot of chemical industrials choose gas detectors as mitigation equipment to early detect gas vapor. The way of placement of gas detectors has two methods; Code-based Design(CBD) and Performance-based Design. The CBD has principles for gas detectors to be installed with consideration for the place that is expected to accumulate gas, and the leak locations according to legal standards and technical guidelines, and has a possibility to be unable to detect by these rules to locate gas detectors by vapor density information. The PBD has two methods; a Geographic Method and Scenario based Method. The Scenario-based Method has been suggested to make up for the Geographic Coverage Method. This Scenario-based Method draw the best optimum placement of gas detectors by considering leak locations, leak speed information, leak directions and etc. However, the domestic placement guidelines just refers to the CBD. Therefore, this study is to compare existing placement location of gas detectors by the domestic CBD with placement locations, coverages and the number of gas detectors in accordance with the Scenario-based Method. Also this study has measures for early detecting interest of Vapor Cloud and suitable placement of gas detectors to prevent chemical accidents. The Phast software was selected to simulate vapor cloud dispersion to predict the consequence. There are two cases; an accident hole size of leak(8 mm) from API which is the highst accident hole size less than 24.5 mm, and a normal leak hole size from KOSHA Guide (1.8 mm). Detect3D was also selected to locate gas detectors efficiently and compare CBD results and PBD results. Currently, domestic methods of gas detectors do not consider any risk, but just depend on domestic code methods which lead to placement of gas detectors not to make personnels recognize tolerable or intolerable risks. The results of the Scenario-based Method, however, analyze the leak estimated range by simulating leak dispersion, and then it is able to tell tolerable risks. Thus it is considered that individuals will be able to place gas detectors reasonably by making objectives and roles flexibly according to situations in a specific plant.

• Journal of the Korea Society of Computer and Information
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• v.27 no.10
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• pp.11-17
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• 2022

In this paper, a model that can increase the efficiency of work in arranging interior furniture by applying augmented reality technology was studied. In the existing system to which augmented reality is currently applied, there is a problem in that information is limitedly provided depending on the size and nature of the company's product when outputting the image of furniture. To solve this problem, this paper presents an AR labeling algorithm. The AR labeling algorithm extracts feature points from the captured images and builds a database including indoor location information. A method of detecting and learning the location data of furniture in an indoor space was adopted using the CNN technique. Through the learned result, it is confirmed that the error between the indoor location and the location shown by learning can be significantly reduced. In addition, a study was conducted to allow users to easily place desired furniture through augmented reality by receiving detailed information about furniture along with accurate image extraction of furniture. As a result of the study, the accuracy and loss rate of the model were found to be 99% and 0.026, indicating the significance of this study by securing reliability. The results of this study are expected to satisfy consumers' satisfaction and purchase desires by accurately arranging desired furniture indoors through the design and implementation of AR labels.