• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.261-263
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• 2007

Authentication is a mechanism to establish proof of identities, the authentication process ensure that. Who a particular user is. Nowadays PC and laptop user authentication systems are always done once a hold until s explicitly revoked by the user, or asking the user to frequently reestablish his identity which encouraging him to disable authentication. Zero-Interaction Authentication (ZIA) provides solution to this problem. In ZIA,. a user wears a small authentication token that communicates with a laptop over a short-range, wireless link. ZIA combine authentication with a file encryption. Here we proposed a Laptop-user Authentication Based Mobile phone (LABM). In our model of authentication, a user uses his Bluetooth-enabled mobile phone, which work as an authentication token that provides the authentication for laptop over a Bluetooth wireless link, m the concept of transient authentication with our combining It with encryption file system. The user authenticate to the mobile phone infrequently. In turn, the mobile phone continuously authenticates to the laptop by means of the short-range, wireless link.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.74-80
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• 2004

If the withdrawal force of strand driven roll which is controlled with predetermined speed isn't distributed regularly in continuous casting process, mold level is changed cyclically and slab quality is not good. In this paper, both casting speed control and load sharing control algorithm of strand driven roll according to ratio which is set up by operator at same time is proposed. The proposed algorithm is to share the withdrawal force by following torque current of each driven roll as average torque current by changing speed reference of each driven roll motor. The load sharing control with anti-wind up for improvement transient state is adopted and the proposed algorithm is implemented in POSCO pilot caster.

• Journal of applied mathematics & informatics
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• v.35 no.3_4
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• pp.241-260
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• 2017

An analysis is made to study the solute transport in a Casson fluid flow through an annulus in presence of oscillatory flow field and determine how this flow influence the solute dispersion along the annular region. Axial dispersion coefficient and the mean concentration expressions are calculated using the generalized dispersion model. Dispersion coefficient in oscillatory flow is found to be a function of frequency parameter, Schmidt number, and the pressure fluctuation component besides its dependency on yield stress of the fluid, annular gap and time in the case of steady flow. Due to the oscillatory nature of the flow, the dispersion coefficient changes cyclically and the amplitude and magnitude of the dispersion increases initially with time and reaches a non - transient state after a certain critical time. This critical value varies with frequency parameter and independent of the other parameters. It is found that the presence of inner cylinder and increase in the size of the inner cylinder inhibits the dispersion process. This model may be used in understanding the dispersion phenomenon in cardiovascular flows and in particular in catheterized arteries.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.9
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• pp.1404-1411
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• 1993

Unlike voice communication, data transmission, can be seriously affected by transient channel impairments. In some cases, timing synchronization between the transmitter and the receiver may not be recovered in the presence of these kinds of impairments without a forced reinitialization process. Therefore, it is highly desirable for data communication equipment to have an efficient timing loss detector for robust recovery. In this paper, one such detector is proposed for data transceivers haying a secondary channel embedded in the main channel. A known sequence multiplexed with the secondary channel data is repeatedly sent through the embedded secondary channel. For continuous watch-dog like operation, the detection is sequentially performed based on a modified up/down counter scheme. The performance of the proposed detector is analytically evaluated In closed form.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.504-504
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• 2000

The flow ratio in the industrial process is usually accomplished by using PID controller with series type ratio. But always the large overshoot and a long rise time may be achieved from this conventional control. These problems are involved to the inexact flow ratio control. In order to avoid this poor performance. the paper presents a designing of the two controller modes for the flow ratio plants. This proposed controller combine the lookup table technique and the well-known PID controller to obtain the fast response and low overshoot of flow ratio control. The PID controller mode will be operated when the flow ratio reaches the preset value while the lookup table technique mode is applied for initial operation. The data in tile table is calculated by the valve sizing equation and convened to the valve position control signal. The experimental results show that the transient and steady state responses of the control systems using the proposed technique can be efficiently obtained when compared with tile conventional controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.406-411
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• 2003

One of the trends on information storage device is focused on the development of micro-optical devices with OFH (Optical Flying Head). Many different types of sliders for OFH and optical component systems have been introduced in the literature. However, the important issue on the mechanical system, which consists of suspension, swing arm and VCM (Voice Coil Motor) part has not been discussed up to date. In this research, we analyses the suspension, which is used for the small form factor MO drive. The analysis is in process two ways. One is probabilistic analysis, another is dynamic shock analysis. Probabilistic analysis is a technique you can use to assess the effect of uncertain input parameters and assumptions on your analysis model. Using a probabilistic analysis you can and out how much the results of a finite elements analysis are affected by uncertainties in the model. Dynamic shock analysis is used for the mobile applications. The mechanical robustness of the suspension simulating the shock responses of a disk-suspension is proposed in this paper.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.7 s.184
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• pp.130-137
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• 2006

TFT-LCD(Thin Film Transistor Liquid Crystal Display) module is representative commercial product of FPD(Flat Panel Display). Thickness of TFT-LCD module is very thin. It is adopted for major display unit for IT devices such as Cellular Phone, Camcorder, Digital camera and etc. Due to the harsh user environment of mobile IT devices, it requires complicated structure and tight assembly. And user requirements for the mechanical functionalities of TFT-LCD module become more strict. However, TFT-LCD module is normally weak to high level transient mechanical shock. Since it uses thin crystallized panel. Therefore, anti-shock performance is classified as one of the most important design specifications. Traditionally, the product reliability against mechanical shock is confirmed by empirical method in the design-prototype-drop/impact test-redesign paradigm. The method is time-consuming and expensive process. It lacks scientific insight and quantitative evaluation. In this article, a systematic design evaluation of TFT-LCD module for mobile IT devices is presented with combinations of FEA and testing to support the optimal shock proof display design procedure.

• Tribology and Lubricants
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• v.21 no.4
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• pp.165-170
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• 2005

Engine lubrication system has very complex oil flow networks. Therefore it is difficult to evaluate and optimize the system only depending on experimental results. When we plan upgrading the engine performance the engine lubrication system must be considered in the plan. In this paper, engine lubrication system design using computational fluid dynamic analysis was studied. To do this, unsteady transient flow network analysis on the engine oil circuit system was carried out. Finally we discussed the design process in the modified engine lubrication system.

• Journal of Welding and Joining
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• v.26 no.6
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• pp.67-73
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• 2008

Three-dimensional transient simulation of laser-GMA hybrid welding involving multiple physical phenomena is conducted neglecting the interaction effect of laser and arc heat sources. To reproduce the bubble and pore formations in welding process, a new bubble model is suggested and added to the established laser and arc welding models comprehending VOF, Gaussian laser and arc heat source, recoil pressure, arc pressure, electromagnetic force, surface tension, multiple reflection and Fresnel reflection models. Based on the models mentioned above, simulations of laser-GMA hybrid butt welding are carried out and besides the molten pool flow, top and back bead formations could be observed. In addition, the laser induced keyhole formation and bubble generation duo to keyhole collapse are investigated. The bubbles are ejected from the molten pool through its top and bottom regions. However, some of those are entrapped by solid-liquid interface and remained as pores. Those bubbles and pores are intensively generated when the absorption of laser power is largely reduced and consequently the full penetration changes to the partial penetration.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.81.2-81.2
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• 2011

The gas diffusion layer (GDL) consists of two main parts, the GDL backing layer, called as a substrate and the micro porous layer (MPL) coated on the GDBL. In this process, carbon particles of MPL penetrates to the GDBL consequently forms MPL penetration part. In this study, the micro porous layer (MPL) penetration thickness is determined as a design parameter of the GDL which affect pore size distribution profile through the GDL inducing different mass transfer characteristics. The pore size distribution and water permeability characteristics of the GDL are investigated and the cell performance is evaluated under fully/low humidification conditions. Transient response and voltage instability are also studied. In addition, to determine the effects of MPL penetration on the degradation, the carbon corrosion stress test is conducted. The GDL that have deep MPL penetration thickness shows better performance in high current density region because of enhanced water management, however, loss of penetrated MPL parts is shown after aging and it induces worse water management characteristics.