• 한국지반신소재학회논문집
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• 제18권4호
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• pp.39-52
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• 2019

In this paper the development and implementation of an artificial intelligence (AI)-based Tunnelling Impact prediction and assessment program (SKKU-iTunnel) is presented. Program predicts tunnelling induced surface settlement and groundwater drawdown by utilizing well trained ANNs and uses these predicted values to perform the damage assessment likely to occur in nearby structures and pipelines/utilities for a given tunnel problem. Generalised artificial neural networks (ANNs) were trained, to predict the induced parameters, through databases generated by combining real field data and numerical analysis for cases that represented real field conditions. It is shown that program equipped with carefully trained ANN can predict tunnel impact assessments and perform damage assessments quiet efficiently and comparable accuracy to that of numerical analysis. This paper describes the idea and implementation details of the SKKU-iTunnel with an example for demonstration.

• ETRI Journal
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• 제42권3호
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• pp.351-365
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• 2020

Directional sensor networks (DSNs) can significantly improve the performance of a network by employing energy efficient communication protocols. Neighbor discovery is a vital part of medium access control (MAC) and routing protocol, which influences the establishment of communication between neighboring nodes. Neighbor discovery is a challenging task in DSNs due to the limited coverage provided by directional antennas. Furthermore, in these networks, communication can only take place when the beams of the directional antennas are pointed toward each other. In this article, we propose a novel multiple token-based neighbor discovery (MuND) protocol, in which multiple tokens are transmitted based on an area exploration algorithm. The performance of the protocol is evaluated using the Cooja simulator. The simulation results reveal that the proposed MuND protocol achieves lower neighbor discovery latency, with a 100% neighbor discovery ratio, and has a relatively low communication overhead and low energy consumption.

• Structural Engineering and Mechanics
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• 제40권5호
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• pp.655-663
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• 2011

Asbestos-cement is a material with valuable strength and durability. It was extensively used for water distribution pipes across the world from the 1950s until the early 1980s. The network of pipes in this case study dates from the 1970s, and after more than 30 to 40 years of service, some pipes have been found to break under common service pressure with no apparent reason. A set of mechanical tests was performed including bending, compression, pressure and crushing tests. Microscopy analysis was also used to understand the material behaviour. Tests showed that there was a clear loss of strength in the pipes and that the safety factor was under the established threshold in most of the specimens. Microscopy results showed morphological damage to the pipes. The loss of strength was attributed to a leaching effect. Leaching damages the cement matrix and reduces the frictional interfacial shear stress.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권9호
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• pp.2399-2418
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• 2023

The paper focuses on investigating secure transmission in wireless powered communication networks (WPCN) that involve multiple energy-constrained relays and one energy-constrained source. The energy is harvested from a power beacon (PB) while operating in the presence of a passive eavesdropper. The study primarily aims to achieve energy-efficient secure communications by examining the impact of channel estimation on the secrecy performance of WPCN under both perfect and imperfect CSI scenarios. To obtain practical insights on improving security and energy efficiency, we propose closed-form expressions for secrecy outage probability (SOP) under the linear energy harvesting (LEH) model of WPCN. Furthermore, we suggest a search method to optimize the secure energy efficiency (SEE) with limited power from PB. The research emphasizes the significance of channel estimation in maintaining the desired performance levels in WPCN in real-world applications. The theoretical results are validated through simulations to ensure their accuracy and reliability.

• Journal of Communications and Networks
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• 제12권1호
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• pp.52-66
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• 2010

Since large objects consume substantial resources, web proxy caching incurs a fundamental trade-off between performance (i.e., hit-ratio and latency) and overhead (i.e., resource usage), in terms of caching and relaying large objects to users. This paper investigates how and to what extent the current dedicated-server based web proxy caching scheme is affected by large file transfers in a high bandwidth campus network environment. We use a series of trace-based performance analyses and profiling of various resource components in our experimental squid proxy cache server. Large file transfers often overwhelm our cache server. This causes a bottleneck in a web network, by saturating the network bandwidth of the cache server. Due to the requests for large objects, response times required for delivery of concurrently requested small objects increase, by a factor as high as a few million, in the worst cases. We argue that this cache bandwidth bottleneck problem is due to the fundamental limitations of the current centralized web proxy caching model that scales poorly when there are a limited amount of dedicated resources. This is a serious threat to the viability of the current web proxy caching model, particularly in a high bandwidth access network, since it leads to sporadic disconnections of the downstream access network from the global web network. We propose a peer-to-peer cooperative web caching scheme to address the cache bandwidth bottleneck problem. We show that it performs the task of caching and delivery of large objects in an efficient and cost-effective manner, without generating significant overheads for participating peers.

• The Journal of Asian Finance, Economics and Business
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• 제9권5호
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• pp.497-506
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• 2022

The study was carried out to investigate the factors affecting the online purchase intention of Vietnamese consumers, focusing on Generation Z (Gen Z), through the information provided on TikTok - a social media network. Besides, the study evaluates the influence of these factors on the intention to purchase online of Gen Z. Most important; the research aims to help businesses better understand the insight of their consumers. The data were collected from 250 people who were born in the 1995 to 2010 period, living in the South of Vietnam. The study was conducted from December 2021 to March 2022 and used two analytical methods, which are exploratory factor analysis and Structural Equation Modeling. Research results show that there are 4 factors of TikTok advertisements that affect the purchase intention of Gen Z consumers, including information, entertainment, trust, and social interaction, and they all have a positive impact on the online purchase intention. In which the information factor has the most significant impact on the online purchase intention of Gen Z consumers. Based on the research results, recommendations are made to help businesses that have sold or intend to sell products via TikTok, improve the effectiveness of advertisement through the TikTok channel.

• International Journal of Computer Science & Network Security
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• 제23권7호
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• pp.171-185
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• 2023

The cardiovascular syndrome is the dominant reason for death and the number of deaths due to this syndrome has greatly increased recently. Regular cardiac monitoring is crucial in controlling heart parameters, particularly for initial examination and precautions. The quantity of cardiac patients is rising each day and it would increase the load of work for doctors/nurses in handling the patients' situation. Hence, it needed a solution that might benefit doctors/nurses in monitoring the improvement of the health condition of patients in real-time and likewise assure decreasing medical treatment expenses. Regular heart monitoring via wireless body area networks (WBANs) including implantable and wearable medical devices is contemplated as a life-changing technique for medical assistance. This article focuses on the latest development in wearable and implantable devices for cardiovascular monitoring. First, we go through the wearable devices for the electrocardiogram (ECG) monitoring. Then, we reviewed the implantable devices for Blood Pressure (BP) monitoring. Subsequently, the evaluation of leading wearable and implantable sensors for heart monitoring mentioned over the previous six years, the current article provides uncertain direction concerning the description of diagnostic effectiveness, thus intending on making discussion in the technical communal to permit aimed at the formation of well-designed techniques. The article is concluded by debating several technical issues in wearable and implantable technology and their possible potential solutions for conquering these challenges.

• IMMUNE NETWORK
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• 제24권2호
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• pp.17.1-17.16
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• 2024

We have reported that anterior cruciate ligament (ACL) injury leads to the differential dysregulation of the complement system in the synovium as compared to meniscus tear (MT) and proposed this as a mechanism for a greater post-injury prevalence of post traumatic osteoarthritis (PTOA). To explore additional roles of complement proteins and regulators, we determined the presence of decay-accelerating factor (DAF), C5b, and membrane attack complexes (MACs, C5b-9) in discarded surgical synovial tissue (DSST) collected during arthroscopic ACL reconstructive surgery, MT-related meniscectomy, osteoarthritis (OA)-related knee replacement surgery and normal controls. Multiplexed immunohistochemistry was used to detect and quantify complement proteins. To explore the involvement of body mass index (BMI), after these 2 injuries, we examined correlations among DAF, C5b, MAC and BMI. Using these approaches, we found that synovial cells after ACL injury expressed a significantly lower level of DAF as compared to MT (p<0.049). In contrast, C5b staining synovial cells were significantly higher after ACL injury (p<0.0009) and in OA DSST (p<0.039) compared to MT. Interestingly, there were significantly positive correlations between DAF & C5b (r=0.75, p<0.018) and DAF & C5b (r=0.64 p<0.022) after ACL injury and MT, respectively. The data support that DAF, which should normally dampen C5b deposition due to its regulatory activities on C3/C5 convertases, does not appear to exhibit that function in inflamed synovia following either ACL injury or MT. Ineffective DAF regulation may be an additional mechanism by which relatively uncontrolled complement activation damages tissue in these injury states.

• International Journal of Internet, Broadcasting and Communication
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• 제7권1호
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• pp.62-65
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• 2015

Wireless Sensor Network consists of several sensor nodes, these nodes loss some of their energy after the process of communication. So an energy efficient approach is required to improve the life of the network. In case of broadcast network, LEACH protocol uses an aggregative approach by creating cluster of nodes. Now the major concern is to built such clusters over WSN in an optimized way. This work presents the improvement over LEACH protocol. Hence we have different work environments where the network is having different capacities. The proposed work shows how the life time of the network will improve when the number of nodes varies within the network.

• 한국컴퓨터정보학회논문지
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• 제22권4호
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• pp.75-82
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• 2017

While the internet has evolved in terms of information sharing and efficiency, it is still prone to security attacks and remains vulnerable even when equipped with a security mechanism. Repeated patching against hacks involves excessive wear of system equipment and high costs. Methods of improving network security include the introduction of security equipment and network partitions, but they have not been fully effective. A fundamental solution is the Operation Content Network (OCN), which enables the strengthening of authentication. In this paper, Instead of following the existing TCP/IP system, OCN establishes an immunity-based security system through content-centric communications. Data transmission occurs over a Content Centric Network (CCN), which is provided with a protocol verified by the CCNx group. Areas protected by OCN rely only on CCN for communication without using any IP. As such, it defends the system against unknown attacks, including zero-day attacks.