• Journal of the Society of Naval Architects of Korea
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• v.35 no.3
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• pp.79-87
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• 1998

The purpose of this paper is to develope a neurofuzzy system for a ship design which can determine efficiently design values e.g. principal dimensions and hull factors in a conceptual design. The neurofuzzy system for a ship design(NeFHull) applies a information about given input-output data to fuzzy theories and deals these fuzzificated values with neural networks, e.g. first, redefines normalized input-output data ad membership functions and then executes these fuzzficated information with backpropagation neural networks. We use a hybrid learning algorithm in the training of neural networks and examine the usefulness of suggested method through mathematical and mechanical examples.

• Geomechanics and Engineering
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• v.25 no.4
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• pp.317-330
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• 2021

This paper reports the results of advanced data analysis involving artificial neural networks for the prediction of the unconfined compressive strength of granite using only two non-destructive test indexes. A data-independent site-independent unbiased database comprising 182 datasets from non-destructive tests reported in the literature was compiled and used to train and develop artificial neural networks for the prediction of the unconfined compressive strength of granite. The results show that the optimum artificial network developed in this research predicts the unconfined compressive strength of weak to very strong granites (20.3-198.15 MPa) with less than ±20% deviation from the experimental data for 70% of the specimen and significantly outperforms a number of available models available in the literature. The results also raise interesting questions with regards to the suitability of the Pearson correlation coefficient in assessing the prediction accuracy of models.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.693-698
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• 2001

Ab initio density functional calculations on the structural isomers, the hydration energies, and the hydrogen bond many-body interactions for gauche-, trans-protonated ethylenediamine-(water)3 complexes (g-enH+(H2O)3, t-enH+(H2O)3) have been performed. The structures and relative stabilities of three representative isomers (cyclic, tripod, open) between g-enH+(H2O)3 and t-enH+(H2O)3 are predicted to be quite different due to the strong interference between intramolecular hydrogen bonding and water hydrogen bond networks in g-enH+(H2O)3. Many-body analyses revealed that the combined repulsive relaxation energy and repulsive nonadditive interactions for the mono-cyclic tripod isomer, not the hydrogen bond cooperativity, are mainly responsible for the greater stability of the bi-cyclic isomer.

• The Journal of Information Technology
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• v.5 no.4
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• pp.129-137
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• 2002

In this paper, a public key knapsack cryptosystem algorithm is based on the security to a difficulty of polynomial factorization in computer communication networks is proposed. For the proposed public key knapsack cryptosystem, a polynomial vector Q(x,y,z) is formed by transform of superincreasing vector P, a polynomial g(x,y,z) is selected. Next then, the two polynomials Q(x,y,z) and g(x,y,z) is decided on the public key. The enciphering first selects plaintext vector. Then the ciphertext R(x,y,z) is computed using the public key polynomials and a random integer $\alpha$. For the deciphering of ciphertext R(x,y,z), the plaintext is determined using the roots x, y, z of a polynomial g(x,y,z)=0 and the increasing property of secrety key vector. Therefore a public key knapsack cryptosystem is based on the security to a difficulty of factorization of a polynomial g(x,y,z)=0 with three variables. The propriety of the proposed public key cryptosystem algorithm is verified with the computer simulation.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.4
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• pp.309-315
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• 2018

Currently, the commercialization of the $5^{th}$ Generation (5G) service is becoming more prevalent in domestic communication network technology. This has reduced communication delay time and enabled large-capacity data transmission and video streaming services in real-time. In order to keep pace with these developments, K-water has introduced a smart process control system in water purification plants to monitor the status of the water purification process. However, since wireless networks are based on the public Long Term Evolution (LTE) network, communication delay time remains high, and high-resolution video services are limited. This is because communication networks still have a closed structure due to expense and security issues. Therefore, with 5G in its current form, it is very difficult to accommodate future services without improving the infrastructure of its communication networks. In recognition of these problems, this study implemented the authentication and management function of wireless networks on a wired network management system in the K-water Bansong water purification plant. The results confirmed that wired Local Area Network (LAN) services give a higher security performance than an expensive commercial wireless LAN system. This was achieved by using an Internet Protocol (IP) address management system of wired networks and the packet filtering function of the Layer2 (L2) switch. This study also confirmed that it is possible to create a wireless LAN service that is 3.7 times faster than the existing LTE communication network.

• Convergence Security Journal
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• v.7 no.1
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• pp.77-82
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• 2007

Supporting Quality of Service (QoS) for multimedia services in heterogeneous mobile networks is a part of key issue for Beyond Three Generation (B3G) development. In particular, if QoS degradation are occurred because cell overload and error late patterns of wireless links during the transmission of multimedia data, the efficient QoS management is necessary to maintain the same QoS of transmitted multimedia data because the QoS may be defected by some delay and information loss. This paper deals with QoS Degradation reason Intra-System Handover (D-ISHO) for handling QoS of multimedia services over heterogeneous mobile networks. For this aim, the function modules for supporting QoS of D-ISHO are proposed. The sequence diagram showing interaction between the modules is described and then a scenario for D-ISHO is considered. Simulation is focused on the average delay and packet loss rate. The proposed heterogeneous mobile system using the QoS-Guaranteed Resource Management (QGRM) provides a better performance than each different access system.

• Structural Engineering and Mechanics
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• v.75 no.3
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• pp.295-309
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• 2020

The construction of Reinforced Concrete (R/C) buildings with unreinforced masonry infills is part of the traditional building practice in many countries with regions of high seismicity throughout the world. When these buildings are subjected to seismic motions the presence of masonry infills and especially their configuration can highly influence the seismic damage state. The capability to avoid configurations of masonry infills prone to seismic damage at the stage of initial architectural concept would be significantly definitive in the context of Performance-Based Earthquake Engineering. Along these lines, the present paper investigates the potential of instant prediction of the damage response of R/C buildings with various configurations of masonry infills utilizing Artificial Neural Networks (ANNs). To this end, Multilayer Feedforward Perceptron networks are utilized and the problem is formulated as pattern recognition problem. The ANNs' training data-set is created by means of Nonlinear Time History Analyses of 5 R/C buildings with a large number of different masonry infills' distributions, which are subjected to 65 earthquakes. The structural damage is expressed in terms of the Maximum Interstorey Drift Ratio. The most significant conclusion which is extracted is that the ANNs can reliably estimate the influence of masonry infills' configurations on the seismic damage level of R/C buildings incorporating their optimum design.

• International Journal of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.8-19
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• 2019

Since their emergence in 2007, smart phones have advanced up to the point that 5G mobile communication in 2019 started to be commercialized. Accordingly, now it is possible to share 3D modeling files and collaborate by means of a mobile web. As the recently commercialized 5G mobile communication network is so useful in sharing 3D modeling files and collaborating that even large-size geometry files can be transmitted at ultra high speed with ultra low transfer delay. We examines characteristics of major 3D file formats such as STL, OBJ, FBX, and glTF and compares the existing 4G LTE (Long Term Evolution) network with the 5G NR (New Radio) mobile communication network. The loading time and packets of each format were measured depending on the mobile web browser environments. We shows that in comparison with 4G LTE, the loading time of STL and OBJ file formats were reduced as much as 6.55 sec and 9.41 sec, respectively in the 5G NR and Chrome browsers. The glTF file format showed the most efficient performance in all of the 4G/5G mobile communication networks, Chrome, and Edge browsers. In the case of STL and OBJ, the traffic was relatively excessive in 5G NR and Edge browsers. The findings of this study are expected to be utilized to develop a 3D file format that reduces the loading time in a mobile web environment.

• Journal of Communications and Networks
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• v.4 no.4
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• pp.344-350
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• 2002

This work summarizes the current state of the art in software radio for 4G systems. Specifically, this work demonstrates that classic radio structures, e.g., heterodyne reception, homodyne reception, and their improved implementations, are inadequate selections for multi-mode reception. This opens the door to software defined radio, a novel reception architecture which promises ease in multi-band, multi-protocol design. The work presents the many advantages of such an architecture, including flexibility, reduced cost via component reduction, and improved reliability via, e.g., the elimination of environmental instability. The work also explains the limitations that currently curtail the widespread use of SDR, including issues surrounding A/D converters, management of software and power, and clock generation. This provides direction for future research to enable the broad applicability of SDR in 4G cellular and beyond.

• Electronics and Telecommunications Trends
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• v.37 no.4
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• pp.46-59
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• 2022

The 5G MEC (Multi-access Edge Computing) technology offers network and computing functionalities that allow application services to improve in terms of network delay, bandwidth, and security, by locating the application servers closer to the users at the edge nodes within the 5G network. To offer its interoperability within various networks and user equipment, standardization of the 5G MEC technology has been advanced in ETSI, 3GPP, and ITU-T, primarily for the MEC platform, transport support, and MEC federation. This article offers a brief review of the standardization activities for 5G MEC technology and the details about the system architecture and functionalities developed accordingly.