• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.143-152
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• 1997

The deflection of an end mill is very important in machining process and cutting simulation because it affects directly workpiece accuracy, cutting force, and chattering. In this study, the deflection of the end mill was studied both experimentally and by using finite element analysis. And the moment of inertia of cross sections of the helical end mill is calculated for the determination of the relation between geometry of radial cross section and rigidity of the tools. Using the Bernoulli-Euler beam theory and the concept of equivalent diameter, a deflection model is established, which includes most influences from tool geomety parameters. It was found that helix angle attenuates the rigidity of the end mill by the finite element analysis. As a result, the equivalent diameter is determined by tooth number, inscribed diameter ratio, cross sectional geometry and helix angle. Because the relation betweem equivalent diameter and each factor is nonlinear, neural network is used to decide the equivalent diameter. Input patterns and desired outputs for the neural network are obtained by FEM analysis in several case of end milling operations.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.1
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• pp.151-160
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• 2024

Artificial Neural Networks that enabled Artificial Intelligence are being used in many fields. However, the application to mechanical structures has several problems and research is incomplete. One of the problems is that it is difficult to secure a large amount of data necessary for learning Artificial Neural Networks. In particular, it is important to detect and recognize external forces and forces for safety working and accident prevention of mechanical structures. This study examined the possibility by applying the Current Neural Network of Artificial Neural Networks to detect and recognize the load on the machine. Tens of thousands of data are required for general learning of Recurrent Neural Networks, and to secure large amounts of data, this paper derives load data from ANSYS structural analysis results and applies a stacked auto-encoder technique to secure the amount of data that can be learned. The usefulness of Stacked Auto-Encoder data was examined by comparing Stacked Auto-Encoder data and ANSYS data. In addition, in order to improve the accuracy of detection and recognition of load data with a Recurrent Neural Network, the optimal conditions are proposed by investigating the effects of related functions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.35-42
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• 2021

This paper presents an on-line finite element model updating method for in-service structures using measured data. Conventional updating methods, which are based on numerical optimization, are not efficient for on-line updating because they generally require repeated eigenvalue analyses until convergence criteria are met. The proposed method enables fully automated on-line finite element model updating, almost simultaneously with vibration measurement, without any user intervention or off-line procedures. The automated covariance-driven stochastic subspace identification (Cov-SSI) method is utilized to identify modal frequencies and vectors, and the identified modal data is fed to the neural network of the inverse eigenvalue function to produce the updated finite element model parameters. Numerical examples for a wind excited 20-story building structure shows that the proposed method can update the series of finite element model parameters automatically. It is also shown that sudden changes in the structural parameters can be detected and traced successfully.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.25-32
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• 2017

We are living in networks which are regarded as a society. However, it is difficult to designate a specific position or the impact over sociological relationships and virtual links. In this paper, we conceptualize two themes of the network as Physical Network and Virtual Network, and observe their cross-network effects. New concept called Networked Community (NC) is then introduced to walk through both PN and VN by using the element of connections say connectivity feature. Through modeling NC by the theme of network transposition and egocentric network, we try to comprehend all possible networks for detecting the problems and solutions by using both sides' idea. Experimental results show that we can model real-world problems and then analyze them through NC by measurable and structural manner.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.80-82
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• 2004

Personal robot consist of various modules that have independent functions. Because personal robot has requirement that support various construction for user's tendency. Therefore, Middleware mechanism at support not only personal robot's main functional element but also embedded modules functional elements is required. Each module have various heterogeneous network interfaces and variable services and variables. Therefore, Middleware must support these various network interfaces. This paper, pointed in Controller Area Network(CAN) inreface that usually used in embedded system for control. For connect various heterogeneous network interfaces (Ethernet, RS232 etc..), it is necessary to modify bagic CAN frame format. And also make some kind of BUS topology for CAN network.

• Computational Structural Engineering
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• v.11 no.1
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• pp.179-190
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• 1998

A geometrically nonlinear finite element formulation of spatial cable networks is presented using two cable elements. Firstly, derivation procedures of tangent stiffness and mass matrices for the space truss element and the elastic catenary cable element are summarized. The load incremental method based on Newton-Raphson iteration method and the dynamic relaxation method are presented in order to determine the initial static state of cable nets subjected to self-weights and support motions. Furthermore, static non-linear analysis of cable structures under additional live loads are performed based on the initial configuration. Challenging example problems are presented and discussed in order to demonstrate the feasibility of the present finite element method and investigate static nonlinear behaviors of cable nets.

• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.5
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• pp.6-11
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• 1972

A general active RC network synthesis procedure which realizes any stable transfer function is described. The network elements are only R's, C's and OA's, and the network configuration are well suited for construction using thin-film RC networks and integrated cil'suit operational amplifiers. Poles and transmission zeros can be adjusted independently to each other and are qu;te insensitive to element variations.

• 전기의세계
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• v.22 no.2
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• pp.40-44
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• 1973

A method for obtaining state equation for nonlinear time-varying RLC networks is presented. The nonlinear time-varying RLC elements are decomposed by using Murata method to formulate nonlinear state equation. A nonlinear time-varying RLC network containing twin tunnel diode is solved as an example. In consequence of solving the examjple, simple methods are presented for revising the original network model so that the formulation of state equation is simplified.

• Geomechanics and Engineering
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• v.22 no.2
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• pp.133-142
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• 2020

The evolution of the mining-induced fracture network formed during longwall top coal caving (LTCC) has a great influence on the gas drainage, roof control, top coal recovery ratio and engineering safety of aquifers. To reveal the evolution of the mining-induced stress and fracture network formed during LTCC, the fracture network in front of the working face was observed by borehole video experiments. A discrete element model was established by the universal discrete element code (UDEC) to explore the local stress distribution. The regression relationship between the fractal dimension of the fracture network and mining stress was established. The results revealed the following: (1) The mining disturbance had the most severe impact on the borehole depth range between approximately 10 m and 25 m. (2) The distribution of fractures was related to the lithology and its integrity. The coal seam was mainly microfractures, which formed a complex fracture network. The hard rock stratum was mainly included longitudinal cracks and separated fissures. (3) Through a numerical simulation, the stress distribution in front of the mining face and the development of the fracturing of the overlying rock were obtained. There was a quadratic relationship between the fractal dimension of the fractures and the mining stress. The results obtained herein will provide a reference for engineering projects under similar geological conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6C
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• pp.535-543
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• 2002

In order to overcome disadvantages of existing centralized network management systems that use simple objects, dynamic object platforms are proposed as alternative systems. So the distributed network management systems are implemented using various distributed platform such as CORBA and Java-RMI. Subsequently mobile agent-based platforms are proposed. The mobile agent-based platform can additionally provide flexibility and scalability to network management system that CORBA or Java-RMI based platforms do not support. In this paper, we address an architecture to solve the problem of the occurrence of additional traffic by using mobile agent and to save resources of network element. Our proposal in this paper is an efficient network management architecture using motile agents. And we make use of mobile agents for minimizing of traffic that can happen when mobile agents moves. Also we design agents using information architecture of TMN for efficient resource management of network element and improvement of operation performance.