• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.6
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• pp.93-103
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• 2009

Recently, there is an increase in demand of real-time multimedia service in the WLAN environment, with a commercialization of IEEE 802.11n standard. However, the 802.1x authentication protocol is too slow to provide seamless real-time multimedia service, which defined in an IEEE 802.11i security standard. In this paper, a Ticket-based authentication mechanism in the CAPWAP(Control And Provisioning Wireless Access Point) architecture is introduced to support for the fast handoff.

• Medical Lasers
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• v.9 no.1
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• pp.6-11
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• 2020

Hydrogels have been developed and used in tissue engineering and regenerative medicine to deliver therapeutics to injured or diseased tissue because of their versatility and properties that can be tailored to match the natural extracellular matrix. Hydrogels can be made with a variety of physical and chemical properties combined with light responsiveness ideal for applications in different fields of medicine that require the spatiotemporal control of therapeutics. Light, as a stimulus, is relatively inexpensive, contact-free, noninvasive with high spatial resolution and temporal control, convenient and easy to use, and allows deep tissue penetration that is relatively harmless. Photoresponsive hydrogels are ideal candidates for on-demand drug delivery systems that are capable of sustained and controlled drug release, minimizing the side effects, and ensuring the activity and efficient delivery of drugs to the target tissue.

• International Journal of Computer Science & Network Security
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• v.23 no.12
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• pp.194-198
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• 2023

The current electricity networks will undergo profound changes in the years to come to be able to meet the growing demand for electricity, while minimizing the costs of consumers and producers, etc. The electricity network of tomorrow or even the intelligent « Smart Grids » network will be the convergence of two networks: the electricity network and the telecommunications network. In this context falls our work which aims to study the impact of the integration of energy decentralization into the electricity network. In this sense, we have implemented a new smart grid model where several coexisting suppliers can exchange information with consumers in real time. In addition, a new approach to energy distribution optimization has been developed. The simulation results prove the effectiveness of this approach in improving energy exchange and minimizing consumer purchase costs and line losses.

• Clinics in Shoulder and Elbow
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• v.26 no.4
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• pp.455-461
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• 2023

Arthroscopic shoulder procedures are one of the most common procedures used to restore function through minimally invasive techniques. With the demand for shoulder arthroscopic procedures comes the need for safe, effective, and efficient surgery that maximizes patient outcomes while minimizing complications. Many variables contribute to visualization in shoulder arthroscopy including vascular anatomy, blood pressure control, arthroscopic pump systems, turbulence control, epinephrine, and tranexamic acid. Furthermore, patient positioning can have a dramatic effect on visualization with both the beach chair position and lateral decubitus positioning having various strengths and weaknesses depending on the intended procedure being performed. The purpose of this review is to examine the benefits and complications reported in the literature for improving visualization in shoulder arthroscopy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2657-2662
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• 2010

Demand on information security in mobile devices based control system grows rapidly with a view to counteracting information hacking and leakage. Among these techniques, encryption and authentication are most common. This paper presents CBC-MAC (Cipher Block Chaining-Message Authentication Code) based mobile devices control system. The system is termed as Secure Mobile in Vehicle (SMIV)We use CBC-MAC that is one of the most efficient authentication modes to protect information against any malicious attacks. By sharing the secret key of CBC-MAC between the transmitter and receiver, it asserts authentic information. The proposed system is verified in such a way that we develop mobile devices control system, apply the CBC-MAC algorithm to the control system and validate the received data. Unlike conventional systems where the development of control mechanism in mobile devices based control systems is main concern, this proposed system offers a secure communication link of the data in mobile devices control system and therefore would be useful to the design and implementation of various mobile devices based control systems.

• Earthquakes and Structures
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• v.12 no.4
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• pp.425-436
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• 2017

Vibration control using a tuned mass damper (TMD) is an effective technique that has been verified using analytical methods and experiments. It has been applied in mechanical, automotive, and structural applications. However, the damping of a TMD cannot be adjusted in real time. An excessive mass damper stroke may be introduced when the mass damper is subjected to a seismic excitation whose frequency content is within its operation range. The semi-active tuned mass damper (SATMD) has been proposed to solve this problem. The parameters of an SATMD can be adjusted in real time based on the measured structural responses and an appropriate control law. In this study, a stiffness-controllable TMD, called a leverage-type stiffness-controllable mass damper (LSCMD), is proposed and fabricated to verify its feasibility. The LSCMD contains a simple leverage mechanism and its stiffness can be altered by adjusting the pivot position. To determine the pivot position of the LSCMD in real time, a discrete-time direct output-feedback active control law that considers delay time is implemented. Moreover, an identification test for the transfer function of the pivot driving and control systems is proposed. The identification results demonstrate the target displacement can be achieved by the pivot displacement in 0-2 Hz range and the control delay time is about 0.1 s. A shaking-table test has been conducted to verify the theory and feasibility of the LSCMD. The comparisons of experimental and theoretical results of the LSCMD system show good consistency. It is shown that dynamic behavior of the LSCMD can be simulated correctly by the theoretical model and that the stiffness can be properly adjusted by the pivot position. Comparisons of experimental results of the LSCMD and passive TMD show the LSCMD with less demand on the mass damper stroke than that for the passive TMD.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7B
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• pp.440-449
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• 2005

This paper proposes the measurement scheme for network overload and the control technique in case of breaking several control channels when we support the call services of DAMA through communication satellite(GEO, Geostationary Earth Orbit). And its performance is analyzed. The proposed schemes measure the overload of access control channel of a network controller to control the call connections, detect the level of network overload, notify the terminals of DAMA network of the state, and excute overload control. As a result, it improves the system performance and the network stability at overload state. Moreover hysteresis is applied to the change of overload state for the restriction of the frequent state shifts. The results show that the proposed algorithm prevents excessive increment of call-setup delay and too much lowering of call success rate, and improves the network stability.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.2
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• pp.107-112
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• 2013

In the paper, velocity controller of switching module and temperature controller for the high-voltage static var compensator are proposed. Because of the continuous increase in demand for electric power, transmission and distribution facilities of power plant are required. There is a bottleneck problem of transportation routes according to new construction and expansion of power transmission facilities. Therefore there are researches to maximize the utilization of existing facilities and to increase transmission capacity without new construction. The previous static var compensator detects voltage of input circuit of power, switches the SCR directly and generates switching noise. The proposed method increases switching velocity and decreases noise using switching control based on the voltage between both sides of SCR. Also the proposed method enhance the stability using realtime temperature control for heating of the system from increase of switching velocity. We experiment the velocity and temperature control of the proposed high-voltage static var compensator in the real environment and verify the performance of the proposed system by applying in the real field.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.4
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• pp.330-336
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• 2004

To meet the increasing demand from various fishing fields for training of fishing equipment operators, a fishing winch simulator was designed to train maritime students in the correct and safe operation of hydraulic winches under various load conditions related to fishing operations. The aim of this study is to describe the basic dynamic characteristics of the newly developed hydraulic fishing winch simulator and particularly to analyze the mechanical responses produced on the winch operation controls. The winch simulator consists of two winch units, a computer control and data acquisition system, a control consol and other associated mechanisms. When one winch is in hauling mode, the other one will always be in loading mode. The revolution speed of the hauling winch was controlled by a proportional directional control valve, and the braking torque of the loading winch was controlled by a proportional pressure control valve. The simulation experiments indicated that the dynamic characteristics of the hauling winch followed the braking response characteristics of the loading winch. The tests also showed that the warp speed and tension linearly depend on the pressure differential across the motor of the loading winch controlled by operating the proportional pressure control valve during the hauling operation. The experience gained from various training courses showed that the fishing winch simulator was very realistic and it was valuable for training novice winch operators. The results of the winch simulation exercise were recorded and used to evaluate the training on the operation and handling of the winch system. From these test results, we concluded that the tension acting on the warp during hauling operations can successfully be simulated by controlling the pressure differential across the motor with step changes of the control input signal to the proportional pressure control valve of the loading winch.

• Convergence Security Journal
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• v.24 no.2
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• pp.39-45
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• 2024

The purpose of security control in the public sector is to secure the safety of administrative services for the public by preventing resource loss or information infringement in information systems and information and communication networks. The security control system is a process that performs real-time detection, analysis, response, and reporting through system vulnerability analysis and security system detection pattern optimization. This study aims to objectively identify the current situation of the mismatch between the supply and demand of cyber security control centers currently in operation and specialized security control companies that can be entrusted to operate them, and to derive and propose practical and institutional improvement measures. Considering that the operation of security control centers in the public sector is expected to increase in the future, research on the practical supplementation required for the operation process of security control centers and the improvement of the designation system of security control specialized organizations has fundamental and timely significance, and it is an area that requires continuous research in terms of strategic industrialization.