• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.3
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• pp.9-18
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• 2008

Mobile devices do not need the fixed network infrastructure in ad-hoc network, these devices communicate each other through the distributed control. Accordingly, mobile devices can discover several services using dynamic searching method and provide safely public ownership of these services. Ad-hoc network needs the distributed control and topology of dynamic network because the limited power for processing and network communication. This paper is devoted to provide the secure protocol that provides efficient services discovery using SDP(Service Discovery Protocol) and considers the security requirements. Proposed protocol provides the distributed control based on PKI without central server, the discovery of trusted service, secure telecommunication, the identification among mobile devices, and service access control by user authority.

• Smart Structures and Systems
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• v.23 no.6
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• pp.615-626
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• 2019

Inerter-based damping devices (IBBDs), which consist of inerter, spring and viscous damper, have been extensively investigated in vehicle suspension systems and demonstrated to be more effective than the traditional control devices with spring and viscous damper only. In the present study, the control performance on cable vibration reduction was studied for four different inerter-based damping devices, namely the parallel-connected viscous mass damper (PVMD), series-connected viscous mass damper (SVMD), tuned inerter dampers (TID) and tuned viscous mass damper (TVMD). Firstly the mechanism of the ball screw inerter is introduced. Then the state-space formulation of the cable-TID system is derived as an example for the cable-IBBDs system. Based on the complex modal analysis, single-mode cable vibration control analysis is conducted for PVMD, SVMD, TID and TVMD, and their optimal parameters and the maximum attainable damping ratios of the cable/damper system are obtained for several specified damper locations and modes in combination by the Nelder-Mead simplex algorithm. Lastly, optimal design of PVMD is developed for multi-mode vibration control of cable, and the results of damping ratio analysis are validated through the forced vibration analysis in a case study by numerical simulation. The results show that all the four inerter-based damping devices significantly outperform the viscous damper for single-mode vibration control. In the case of multi-mode vibration control, PVMD can provide more damping to the first four modes of cable than the viscous damper does, and their maximum control forces under resonant frequency of harmonic forced vibration are nearly the same. The results of this study clearly demonstrate the effectiveness and advantages of PVMD in cable vibration control.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.81-88
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• 2017

This study deals with the optimal design of a hybrid control system composed of a combination of active control system and passive control system for effective seismic performance improvement of two adjacent structures. The proposed hybrid control system adopts a configuration of installing an active control device in one building and connecting two adjacent structures with a passive control device so that the one-side active control force can be bi-directionally applied to both buildings through the passive connecting devices. In order to derive the optimal performance of the proposed system, the design parameters of the passive and active control systems were searched using the genetic algorithm. Numerical simulations of 10-story and 8-story buildings have been performed to verify the effectiveness of the proposed technique. For the purpose of comparison, the conventional independent control system with two identical active control systems being installed separately for each structure was also optimally designed and its seismic response has been evaluated as well. From the comparative results of the two control systems, it is demonstrated that the proposed hybrid control system requires larger control force for its one-side active control device than the conventional independent control system does for each of both-side active devices, but quite less than the total control force required for both-side devices of the independent control system, while maintaining similar seismic performance. Therefore, the proposed system is more economical and reliable than the conventional independent control system with two identical active devices.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.91-100
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• 2007

Many manufacturing devices must execute motions as quickly as possible to achieve profitable high-volume production. Most of them have devices having flexibility and a time delay of one sampling is added to the plants when they are controlled by fast discrete controllers, which brings about non-minimum phase zeros. This paper develops a control strategy that combines feedforward and feedback control with command shaping for such devices. First, the feedback controller is designed to increase damping and eliminate steady-state error. Next, the feedforward controller is designed to speed up the transient response. Finally, an appropriate reference profile is generated using command-shaping techniques to ensure fast point-to-point motions with minimum residual vibration. The particular focus of the paper is to understand the interactions between these individual control components. The resulting control strategy is demonstrated on a model of a high-speed semiconductor manufacturing machine.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.56-63
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• 2014

This study proposes a new control approach for efficient vibration suppression of two identical adjacent structures. The conventional control approach of two adjacent structures is to interconnect the two structures with passive, semi-active or active control devices. However, when the two adjacent structures are identical to each other, their dynamical behaviors such as frequency and damping properties are also the same. In this case, the interconnected control devices cannot exhibit the dissipative control forces on the both structures as expected since the relative displacements and velocities of the devices become close to zero. In other words, the interconnection method does not work for the twin structures as enough as expected. In order to solve this problem, we propose several new control approaches to effectively and efficiently reduce the identically-fluctuating responses of the adjacent structures with minimum control efforts. In order to demonstrate the proposed control systems, the proposed several control systems are optimally designed and their control performances are compared with that of the conventional optimal control system where each TMD(tuned mass damper) is installed in each structure for independent control purpose. The simulated results show that one of the proposed control systems(System 04) is able to guarantee enhanced control performance compared with the conventional system.

• Knowledge Management Research
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• v.22 no.3
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• pp.173-199
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• 2021

As the use of smart devices such as smartphones and tablets has become common, the time to start using smart devices is getting earlier, such as using smart devices from the age of one. Also, the use of smart devices by infants and toddlers is continuously increasing. Smart devices have become convenient means of acquiring pleasure and knowledge, but the side effects of addiction and overdependence are becoming issues as much as the benefits of smart devices. This study pays attention to young children's overdependence on smart devices, and focuses on the aspects of parents' perception, control, and observational behavior about smart devices, which can have a profound effect on young children. This study examines how young children's overdependence on smart devices can consequently affect children's characteristics in terms of activity, emotional sensitivity, and social aspects. In particular, this study attempts to explore that the factors influencing children's overdependence on smart devices and the results can vary depending on the moderating variables (parents' control method for children's smart device use, supervision method, and type of contents mainly used). Based on the findings, this study can provide guidelines and implications for parents on how to effectively use smart devices for their young children.

• Journal of Arbitration Studies
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• v.27 no.2
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• pp.83-105
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• 2017

In contemporary society interest in and consumption of beauty treatment are increasing, raising interest in health and beauty. However, beauty-related laws are becoming factors of hindrance of beauty development. Currently the Public Health Control Act plays a basic role in the beauty art business in Korea, However the contents are in discord with international laws and its definition is not clear. Therefore it is causing conflicts of different occupations and job associations which are similar to art business. Especially, because neither definitions nor policies on beauty care devices exist in the Public Health Control Act, beauty care devices using in foreign countries cannot be used in Korea due to classification as medical devices. Under this circumstance, therefore, beauty care device uses by beauty artists violate the law. The government has tried to solve these irrational regulations. Recently, the Small and Medium Business Administration announced 'the improvement plan of small business and young founders site regulation for public economy recovery' in a ministerial meeting on December 28, 2016. Regulations on policy preparation for skincare devices were inclusive in this announcement. It is the question whether the regulations will be executed or not. Even though beauty industrial competitiveness was presented in the 18th Presidential Council on National Competitiveness in 2009, it was not practiced. The proposal bills for beauty law improvement have been put forth several times since 2000 including an improvement plan for regulating beauty care devices. However, so far there have been no improvements. The damage on the regulation classifying beauty devices as medical devices is not only restricted to skincare. This develops beauty devices and the beauty industry which imports and exports beauty devices. When beauty devices are exported, complicated procedures are unavoidable and when beauty devices are imported, irrational problems like reregistration procedures and costs occur. The reason why an improvement plan has not gone into practice is the resistance of the dermatologists' association. Dermatologists tend to stand positively against harming public health by saying that beauty devices used by beauty artists cause people to suffer side effects. In contrast, anyone who has a licence to use beauty devices is able to use them in foreign countries. It is not only infringement of one's right as a beauty artist but also people's right to receive beauty care services. With this reason, Korean's current law under which beauty devices are ruled as medical devices should be revised with accordance to domestic surroundings. Therefore in order to advance and globalize the beauty industry, the support and cooperation of the Korean government and relevant associations is needed to legislate and revise the beauty devices laws. The relevant associations abandon regional self-centeredness and cooperate to define ranges, size and management of beauty devices for safe use. If no collaboration exists, an arbitration agency should be established to solve the problem.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1095-1100
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• 2013

Piezo devices have large power density and simple structure compared with conventional electrical motors. Thus they can generate larger forces than the conventional actuators with small size. Their resopnses to commands are also very fast and thus the bandwidths are very wide. Thus the piezo devices are expected to be used widely in the future for actuating devices requiring fast response and large actuating force with small size. However, the piezo actuators need high voltage with high driving current due to their large capacitive property. In this paper, proposed is a simple method to drive piezo devices using voltage inversion circuit with coli inductance. The coil inductance carries the charges in the piezo device to the opposite side, inverting the polarity of the applied voltage, thus saving the power to drive the device with AC voltages. Experiments with real circuit demonstrates that the proposed scheme can improve the energy efficiency very much.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.43-48
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• 2001

The stability and efficiency of organic light emitting devices are the most critical problems to be solved. The devices based on tris-8-(hydroxyquinoline) aluminum ($Alq_3$) and N,N-diphenyl-N,N-bis(3-methylphenyl)-1, 1-biphenyl-4,4-diamine (TPD) were used to study the effects of buffer layers on their characteristics. We have investigated the characteristic effects of CuPc (copper phthalocyanine) and pentacene buffer layers on the device characteristics, the (5${\sim}$20 nm thick) CuPc layers and the (10${\sim}$20 nm thick) pentacene layers were deposited. Efficiency was slightly improved and the turn-on voltages of the devices with the buffer layers were observed to have lower values than those of the devices without the buffer layers. It is believed that this result is attributed to the improvement of hole injection capability through the buffer layers into hole transport layer (HTL). We have also studied the atomic force microscopic images of the TPD layers deposited on the buffer layer and the bare ITO.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.267-269
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• 2017

As the Internet technology of things is developed, a variety of things Internet devices are emerging. Manufacturers of such Internet devices are registering with the IFTTT to control the device so that the user can use the service. However, most object Internet devices are controlled by smartphone applications, so when a manufacturer uses different devices, many applications should be installed and used. In this paper, we design a smart home service remote control that can control various smart home devices in cooperation with IFTTT automated service platform.