• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1638-1645
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• 2006

This paper proposes a modeling technique which is able to not only reliably and easily represent the hysteretic characteristics but also analyze the dynamic stress of a taper leaf spring. The flexible multi-body dynamic model of the taper leaf spring is developed by interfacing the finite element model and computation model of the taper leaf spring. Rigid dummy parts are attached at the places where a finite element leaf model is in contact with an adjacent one in order to apply contact model. Friction is defined in the contact model to represent the hysteretic phenomenon of the taper leaf spring. The test of the taper leaf spring is conducted for the validation of the reliability of the flexible multi-body dynamic model of the taper leaf spring developed in this paper. The test is started at an unloaded state with the excitation amplitude of $1{\sim}2mm/sec$ and frequency of 132 mm. First, the simulation is conducted with the same condition as the test. Then, the simulations are conducted with various amplitudes in a loaded state. The hysteretic diagram from the test is compared with the ones from the simulation for the validation of the reliability of the model. The dynamic stress analysis of the taper leaf spring is also conducted with the developed flexible multi-body dynamic model under a dynamic loading condition.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.7
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• pp.333-340
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• 2005

One of the most important core technologies required for the design of the ITS (Intrusion Tolerance System) that performs continuously minimal essential services even when the network-based computer system is partially compromised because of the external or internal intrusions is the quantitative dependability analysis of the ITS. In this paper, we applied self-healing mechanism, the core technology of autonomic computing to secure the protection power of the ITS. We analyzed a state transition diagram of the ITS composed of a Primary server and a backup server utilizing two factors of self-healing mechanism (fault model and system response) and calculated the availability of ITS through simulation experiments and also performed studies on two cases of vulnerability attack.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.691-696
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• 2004

The electronic state and chemical bonding of $\beta$-MnO$_2$ with transition metal dopants were theoretically investigated by DV-X$_{\alpha}$ (the discrete variational X$_{\alpha}$) method, which is a sort of the first principles molecular orbital method using the Hartree-Fock-Slater approximation. The calculations were performed with a $_Mn_{14}$ MO$_{56}$ )$^{-52}$ (M = transition metals) cluster model. The electron energy level, the density of states (DOS), the overlap population, the charge density distribution, and the net charges, were calculated. The energy level diagram of MnO$_2$ shows the different band structure and electron occupancy between the up spin states and down spin states. The dopant levels decrease between the conduction band and the valence band with the increase of the atomic number of dopants. The covalency of chemical bonding was shown to increase and ionicity decreased in increasing the atomic number of dopants. Calculated results were discussed on the basis of the interaction between transition metal 3d and oxygen 2p orbital. In conclusion it is expected that when the transition metals are added to MnO$_2$ the band gap decreases and the electronic conductivity increases with the increase of the atomic number of dopants. the atomic number of dopants.

• Archives of design research
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• v.19 no.2 s.64
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• pp.251-260
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• 2006

Rapid development of electronic technology has made it possible to perform various function. But this technology made it increase it's complexity. Therefore, It was important to identify usability problem in interface design. The quality of interface to promote the efficient interaction should be evaluated with regard to users' cognitive characteristics. So, in this paper, washing machine, that is one of the most useful electronic home application was studied menu structure on interface and it's operational states transition. At first, an cognitive menu structure is identified with users' conceptual similarity of the main function of washing machine. Then three washing machines was selected to compare with the cognitive menu structure. And, we were analyzed how operational state of the washing machine was transfered. As a result, we can be revealed that menu operational method based on the cognitive structure was consistent with the user's preferred operational method during the experimental tasks and the users and designers had a different knowledge of an it's function structure. These results will be useful to design the washing machine interface.

• The Journal of Korean Institute of Information Technology
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• v.16 no.12
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• pp.31-40
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• 2018

We designed and implemented the attachable smart adapter for the general management of each company's agricultural machine regardless of whether it is equipped with a CAN (Controller Area Network) module. The smart adapter consists of a main board (Raspberry Pi3B), which operates agricultural machine's management software in Linux environment, and a self-developed interface board for power adjustment and status sensing. For the status monitoring, a sensing interface using a serial input was defined between the smart adapter and the sensors of the agricultural machine, and the state diagram of the agricultural machine was defined for diagnosis. We made a panel to simulate the sensors of the agricultural machine using the switch's on/off contact point, and confirmed the status monitoring and diagnostic functions by inputting each state of the farm machinery from the simulator panel.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.67-79
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• 2009

Because a product in the car industry has a short life cycle in recent years, the process planning and the manufacturing lines have to be changed frequently. Most of time, repositioning an existing facility and modifying used control information are faster than making completely new process planning. However, control information and control code such as PLC code are difficult to understand. Hence, industries prefer writing a new control code instead of using the existing complex one. It shows the lack of information reusability in the existing process planning. As a result, to reduce this redundancy and lack of reusability, we propose a SOS-Net modeling method. SOS-Net is a standard methodology used to describe control information. It is based on the Device Structure which consists of sensor information derived from device hardware information. Thus, SOS-Net can describe a real control state for automated manufacturing systems. The SOS-Net model is easy to understand and can be converted into PLC Code easily. It also enables to modify control information, thus increases the reusability of the new process planning. Proposed model in this paper plays an intermediary role between the process planning and PLC code generation. It can reduce the process planning and implementation time as well as cost.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.221-224
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• 2008

Anghelescu et al. proposed a block cryptosystem based on 8-cell hybrid additive cellular automata with cycle length 8 using state transition rules 51, 60 (or 102). All states must divided into the same cycles in the diagram of the cellular automata. But there exist cellular automata which don't satisfy this condition in Anghelescu et al.'s cryptosystem. In this paper we analyze hybrid additive cellular automata and propose an improved method.

• Transactions on Electrical and Electronic Materials
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• v.15 no.5
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• pp.245-248
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• 2014

$Pt/Al_2O_3/Si_3N_4/SiO_2/Si$ charge trap flash memory structures with various thicknesses of the $Si_3N_4$ charge trapping layer were fabricated. According to the calculated and measured results, we depicted electron loss in a schematic diagram that illustrates how the trap to band tunneling and thermal excitation affects electrons loss behavior with the change of $Si_3N_4$ thickness, temperature and trap energy levels. As a result, we deduce that $Si_3N_4$ thicknesses of more than 6 or less than 4.3 nm give no contribution to improving memory performance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1112-1119
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• 2011

The goal of this study is the stability evaluation of a vacuum pump through modal test and rotor dynamics. Roots type vacuum pump, which is a dry vacuum pump, is necessary for the manufacturing process of the semiconductor and the display. Eigenvalue was solved by the finite-element method(FEM) using 2D and 3D models, then the modal test result was compared with the FEM result. According to the comparison, the analysis result using the 2D was more accurate than the 3D model. Therefore, rotor dynamics was performed by the 2D model. Campbell diagram and root-locus maps, which were calculated by complex-eigenvalue analysis, were used to evaluate the stability of the rotors of the vacuum pump. And displacement solved by unbalance response analysis was compared with the minimum clearance between two rotors of the vacuum pump. Thus, the vacuum pump is assumed operated under steady state through the evaluation of the rotor dynamics.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1833-1837
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• 2004

The two-inertia system, which has the torsion vibration, is typically found in several industrial applications. This torsion vibration will effect the quality of the rolled material as well as the stability of the drive system. Thus the speed and torsion vibration of the system have to be properly controlled. This paper, I-PDA controller designed by Coefficient Diagram Method to control a two-inertia system is proposed. The experimental result shows that both of transient and steady state specification can be fulfilled but the transient response still has long rise time. In order to improve the speed of the system response, a phase lag structure of feedforward controller is introduced to I-PDA control system. It is shown that the performance of the I-PDA control system with suitable FFC has shorter rise and settling times, no overshoot and the torsion vibration can be suppressed.