• Structural Engineering and Mechanics
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• v.62 no.4
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• pp.465-475
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• 2017

Photovoltaic (PV) panels are used in high-rise buildings to convert solar energy to electricity. Due to the considerable energy consumption of high-rise buildings, applying PV technology is of great significance to energy saving. In the application of PV panels, one of the most important construction issues is the connection of the PV panel with the main structures. One major difficulty of the connection design is that the PV panel connection consists of two separate components with coupling and indeterminate dimension. In this paper, the gap element is employed in these two separated but coupled components, i.e., hook and catch. Topology optimization is applied to optimize and design the cross-section of the PV panel connection. Pareto optimization is conducted to operate the optimization subject to multiple load scenarios. The initial design for the topology optimization is determined by the common design specified by the Technical Code for Glass Curtain Wall Engineering (JGJ 102-2003). Gravity and wind load scenarios are considered for the optimization and numerical analysis. Post analysis is conducted for the optimal design obtained by the topology optimization due to the manufactory requirements. Generally, compared with the conventional design, the optimized connector reduces material use with improved structural characteristics.

• IE interfaces
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• v.13 no.4
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• pp.619-626
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• 2000

In this paper, we place the focus on suggesting a method of forecasting demand for PCS resale service with survey data in Korea. It is important for the service provider to forecast the diffusion process when designing marketing strategies and analyzing the costs and benefits. For the reason, we conduct a survey of three groups composed of non-subscribers, cellular subscribers, and PCS subscribers in order to forecast the demand according to several possible scenarios and business strategies. We consider the survey item that is measured by multiple point scales in response to a question if he would subscribe to the mobile telephone service in the future. We propose a method to forecast the size of market potential by classifying each individual into the two extreme groups, that is, yes or no. Then, by integrating survey data and historical data, we forecast the demand for PCS resale service that varies according to scenarios and strategies. From the results, we can find several implications for the provider of PCS resale service.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.187-196
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• 2006

Forecasting the long-term water demand is important in the plan of water supply system because the location and capacity of water facilities are decided according to it. To forecast the long-term water demand, the existing method based on lpcd and population has been usually used. But, these days the trend among the variation of water demand has been disappeared, so expressing other variation of it is needed to forecast correct water demand. To accomplish it, we introduced the System Dynamics method to consider total connections of water demand factor. Firstly, the factors connected with water demand were divided into three sectors(water demand, industry, and population sectors), and the connections of factors were set with multiple regression model. And it was compared to existing method. The results are as followings. The correlation efficients are 0.330 in existing model and 0.960 in SD model and MAE are 3.96% in existing model and 1.68% in SD model. So, it is proved that SD model is superior to the existing model. To forecast the long-term water demand, scenarios were made with variations of employment condition, economic condition and consumer price indexes and forecasted water demands in 2012. After all scenarios were performed, the results showed that it was not needed to increase the water supply ability in Seoul.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.198-206
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• 2019

A new methodology to analyze the nuclear material accountability for pyroprocessing system is developed. The $Pu-to-^{244}Cm$ ratio quantification is one of the methods for Pu accountancy in pyroprocessing. However, an uncertainty in the $Pu-to-^{244}Cm$ ratio due to the non-uniform composition in used fuel assemblies can affect the accountancy of Pu. A random variable, LOPu, is developed to analyze the probability of detection for Pu diversion of hypothetical scenarios at a pyroprocessing facility considering the uncertainty in $Pu-to-^{244}Cm$ ratio estimation. The analysis is carried out by the hypothesis testing and the event tree method. The probability of detection for diversion of 8 kg Pu is found to be less than 95% if a large size granule consisting of small size particles gets sampled for measurements. To increase the probability of detection more than 95%, first, a new Material Balance Area (MBA) structure consisting of more number of Key Measurement Points (KMPs) is designed. This multiple KMP-measurement for the MBA shows the probability of detection for 8 kg Pu diversion is greater than 96%. Increasing the granule sample number from one to ten also shows the probability of detection is greater than 95% in the most ranges for granule and powder sizes.

• Journal of the Korea Safety Management & Science
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• v.25 no.3
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• pp.17-22
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• 2023

As the importance of artificial intelligence grows rapidly and emerges as a leader in technology, it is becoming an important variable in the next-generation industrial system along with the robot industry. In this study, a safety system was developed using deep learning technology to provide worker safety in a robot workplace environment. The implemented safety system has multiple cameras installed with various viewing directions to avoid blind spots caused by interference. Workers in various scenario situations were detected, and appropriate robot response scenarios were implemented according to the worker's risk level through IO communication. For human detection, the YOLO algorithm, which is widely used in object detection, was used, and a separate robot class was added and learned to compensate for the problem of misrecognizing the robot as a human. The performance of the implemented system was evaluated by operator detection performance by applying various operator scenarios, and it was confirmed that the safety system operated stably.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.10
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• pp.2658-2681
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• 2023

In edge computing scenarios, IoT end devices play a crucial role in relaying and forwarding data to significantly improve IoT network performance. However, traditional routing mechanisms are not applicable to this scenario due to differences in network size and environment. Therefore, it becomes crucial to establish an effective and reliable data transmission path to ensure secure communication between devices. In this paper, we propose a trusted path selection strategy that comprehensively considers multiple attributes, such as link stability and edge cooperation, and selects a stable and secure data transmission path based on the link life cycle, energy level, trust level, and authentication status. In addition, we propose the Stability-based On-demand Multipath Distance Vector (STAOMDV) protocol based on the Ad hoc AOMDV protocol. The STAOMDV protocol implements the collection and updating of link stability attributes during the route discovery and maintenance process. By integrating the STAOMDV protocol with the proposed path selection strategy, a dependable and efficient routing mechanism is established for IoT networks in edge computing scenarios. Simulation results validate that the proposed STAOMDV model achieves a balance in network energy consumption and extends the overall network lifespan.

• International Journal of Computer Science & Network Security
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• v.24 no.6
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• pp.23-32
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• 2024

Mobile Ad hoc Network is a network of multiple wireless nodes which communicate and exchange information together without any fixed and centralized infrastructure. The core objective for the development of MANET is to provide movability, portability and extensibility. Due to infrastructure less network topology of the network changes frequently this causes many challenges for designing routing algorithms. Many routing protocols for MANET have been suggested for last few years and research is still going on. In this paper we review three main routing protocols namely Proactive, Reactive and Hybrid, performance comparison of Proactive such as DSDV, Reactive as AODV, DSR, TORA and Hybrid as ZRP in different network scenarios including dynamic network size, changing number of nodes, changing movability of nodes, in high movability and denser network and low movability and low traffic. This paper analyzes these scenarios on the performance evaluation metrics e.g. Throughput, Packet Delivery Ratio (PDR), Normalized Routing Load(NRL) and End To-End delay(ETE).This paper also reviews various network layer security attacks challenge by routing protocols, detection mechanism proposes to detect these attacks and compare performance of these attacks on evaluation metrics such as Routing Overhead, Transmission Delay and packet drop rates.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.5
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• pp.1238-1259
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• 2024

Previous studies on joint optimization of computation offloading and service caching policies in Mobile Edge Computing (MEC) have often neglected the impact of dependency-aware subtasks, edge server resource constraints, and multiple users on policy formulation. To remedy this deficiency, this paper proposes a many-objective joint optimization dependency-aware task offloading and service caching model (MaJDTOSC). MaJDTOSC considers the impact of dependencies between subtasks on the joint optimization problem of task offloading and service caching in multi-user, resource-constrained MEC scenarios, and takes the task completion time, energy consumption, subtask hit rate, load variability, and storage resource utilization as optimization objectives. Meanwhile, in order to better solve MaJDTOSC, a many-objective evolutionary algorithm TSMSNSGAIII based on a three-stage mating selection strategy is proposed. Simulation results show that TSMSNSGAIII exhibits an excellent and stable performance in solving MaJDTOSC with different number of users setting and can converge faster. Therefore, it is believed that TSMSNSGAIII can provide appropriate sub-task offloading and service caching strategies in multi-user and resource-constrained MEC scenarios, which can greatly improve the system offloading efficiency and enhance the user experience.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.3
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• pp.45-49
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• 2001

Wideband code division multiple access (WCDMA) is the most widely adopted third generation air interface. The physical layer of the air interface is the main discussion topic during standardization processes. This paper aims to investigate the performance of uplink WCDMA over many conceivable transmission scenarios in realistic operating conditions. The focus of the study is placed on the performance under frequency selective fading channel conditions with multiple access interference (MAI) in mixed services environments. For the investigation, a simulator has been developed and it encompasses a variety of WCDMA air interface features. The results show that the performance is greatly affected by MAI and is further aggravated with the presence of frequency selective fading, thereby necessitating a suitable compensation measure.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1198-1212
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• 2013

Network virtualization enables autonomous and heterogeneous Virtual Networks (VNs) to co-exist on a shared physical substrate. In a Network Virtualization Environment (NVE), the fact that individual VNs are underpinned by diverse naming mechanisms brings about an obvious challenge for transparent communication across multiple VN domains due to the complexity of uniquely identifying users. Existing solutions were mainly proposed compatible to Internet paradigm with little consideration of their applications in a virtualized environment. This calls for a scalable and efficient naming framework to enable consistent communication across a large user population (fixed or mobile) hosted by multiple VNs. This paper highlights the underlying technical requirements and presents a scalable Global Naming Framework (GNF), which (1) enables transparent communication across multiple VNs owned by the same or different SPs; (2) supports communication in the presence of dynamics induced from both VN and end users; and (3) greatly reduces the network operational complexity (space and time). The suggested approach is assessed through extensive simulation experiments for a range of network scenarios. The numerical result clearly verifies its effectiveness and scalability which enables its application in a large-scale NVE without significant deployment and management hurdles.