• Journal of Communications and Networks
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• v.15 no.1
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• pp.15-24
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• 2013

Provisioning of quality of service (QoS) is a key issue in any multi-media system. However, in wireless systems, supporting QoS requirements of different traffic types is a more challenging problem due to the need to simultaneously minimize two performance metrics - the probability of dropping a handover call and the probability of blocking a new call. Since QoS requirements are not as stringent for non-real-time traffic, as opposed to real-time traffic, more calls can be accommodated by releasing some bandwidth from the already admitted non-real-time traffic calls. If the released bandwidth that is used to handle handover calls is larger than the released bandwidth that is used for new calls, then the resulting probability of dropping a handover call is smaller than the probability of blocking a new call. In this paper, we propose an efficient call admission control algorithm that relies on adaptive multi-level bandwidth-allocation scheme for non-realtime calls. The scheme allows reduction of the call dropping probability, along with an increase in the bandwidth utilization. The numerical results show that the proposed scheme is capable of attaining negligible handover call dropping probability without sacrificing bandwidth utilization.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.4
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• pp.13-23
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• 2017

In order to protect personal information and important information (confidential information, sales information, user information, etc.) in the internal network, companies and organizations apply encryption to the Server-To-Server or Server-To-Client communication section, And are experiencing difficulties due to the increasing number of known attacks and intelligent security attacks. In order to apply the existing S / W encryption technology, it is necessary to modify the application. In the financial sector, "Comprehensive Measures to Prevent the Recurrence of Personal Information Leakage in the Domestic Financial Sector" has been issued, and standard guidelines for financial computing security have been laid out, and it is required to expand the whole area of encryption to the internal network. In addition, even in environments such as U-Health and Smart Grid, which are based on the Internet of Things (IoT) environment, which is increasingly used, security requirements for each collection gateway and secure transmission of the transmitted and received data The requirements of the secure channel for the use of the standard are specified in the standard. Therefore, in this paper, we propose a secure encryption algorithm through mutual authentication and grouping for each node through H / W based Network Control Server (NCS) applicable to internal system and IoT environment provided by enterprises and organizations. We propose a protocol design that can set the channel.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.9-17
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• 2019

Variable guide vanes(VGVs) that consist of link mechanisms and an actuator system are required for an aircraft gas turbine engine to adjust the incidence angle of stator vanes. In this study, we developed a VGV actuator system for three-stage VGVs with two hydraulic actuators. The requirements for the actuator system were derived by analyzing the link mechanisms and air loads, and a hydraulic power-pack was developed based on these requirements. Through a load test using the actuator test-rig and the application of synchronizing control logic with proper control gains, the actuator system could be developed and verified.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.5
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• pp.1829-1846
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• 2021

Transient faults occur in computation units of a processor, which can cause control flow errors (CFEs) and compromise system reliability. The software-based methods perform illegal control flow detection by inserting redundant instructions and monitoring signature. However, the existing methods not only have drawbacks in terms of performance overhead, but also lack of configurability. We propose a configurable approach CCFCA for detecting CFEs. The configurability of CCFCA is implemented by analyzing the criticality of each region and tuning the detecting granularity. For critical regions, program blocks are divided according to space-time overhead and reliability constraints, so that protection intensity can be configured flexibly. For other regions, signature detection algorithms are only used in the first basic block and last basic block. This helps to improve the fault-tolerant efficiency of the CCFCA. At the same time, CCFCA also has the function of solving confusion and instruction self-detection. Our experimental results show that CCFCA incurs only 10.61% performance overhead on average for several C benchmark program and the average undetected error rate is only 9.29%. CCFCA has high error coverage and low overhead compared with similar algorithms. This helps to meet different cost requirements and reliability requirements.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.307-318
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• 2013

Smart grid is composed of variable domains including different systems, and different types of the access control are needed in the multiple domain. Therefore, the access control model suitable for the smart grid environment is required to minimize access control error and deny the unauthorized access. This paper introduce the access control requirements in the smart grid environment and propose the access control model, SG-RBAC, satisfied with the requirements. SG-RBAC model imposes constraints on the access right activation according to the user property, the role property, and the system property. It also imposes constraints on the delegation and the inheritance of access right according to temporal/spatial information and a crisis occurrence.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1223-1234
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• 2016

The Industrial control system is adopted by various industry field and national infrastructure, therefore if it received cyber attack, the serious security problems can be occured in the public sector. For this reason, security requirements of the industrial control system have been proposed, in accordance with the security guidelines of the electronic control system, and it is operated by separate from the external and the internal network. Nevertheless, cyber attack by malware (such as Stuxnet) targeting to control system have been occurred continuously, and also the real-time detection of untrusted traffic is very difficult because there are some difficulty of keeping up with quickly evolving the advent of new-variant malicious codes. In this paper, we propose the traffic analysis architecture for providing secure industrial control system based on the analyzed the security threats, the security requirements, and our proposed architecture.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.24.1-24
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• 1996

The development of future aircraft that involves the expanded flight envelop will place increased performance requirements on the design of the flight control system. Maneuvering areas are expanding into flight envelopes characterized by significantly larger levels of modeling uncertainty than encountered in present flight control designs. Conventional flight control techniques that ignore the effects of large parameter variations, modeling uncertainties and nonlinearities, will likely produce designs with poor performance and robustness. Recent advances in modern control theories called advanced control theories, most notably the H$\_$.inf./ synthesis technique, adaptive control and neural network application, offer the promise of a design technique that can produce both high performance and robust controllers for next generation aircraft. This special lecture will survey the recent development in advanced flight control and review the possible application of advanced control theories.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.49-54
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• 2004

Rule-based access control can not completely be replaced by identity-based access control. Neither can role-based access control be a merger of identity-based access control and rule-based access control, but can be used complementarily for each other. In this paper, is proposed a simulation model designed for a new integrated access control method that has been created by means of integrating the existing access control methods. The integrated access control method is equipped with security, integrity and flow control and can easily accomodate the requirements for access control from role-based corporate bodies. The simulation model proposed in this paper can be applied for real working system designs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.1
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• pp.39-44
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• 1992

Analog PID controllers have been designed to make good use of position control in industries. Recently, the importance of digital position control is emphasized for the requirements of controller which are not only to control the objects but to include various aspects such as easiness of design and implementation, simple exchange of control program and convenient communications of data between various controllers and a host computer. This study proposes a combined control method which is mixed the vaiable structure control (VSC) with the PI control for minimum time position control of DC servo motor by microcomputer. The results of test by this method show offset-free and minimum time optimal position control which is not affected by the disturbance and the system parameter variations. The validity of the proposed method comparing with the conventional PID control is proved by the response experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2696-2700
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• 2003

Nuclear robots should be developed for the reduction of radiation exposure, lower man hours, shorter power outage, and also improved worker safety concerns in performing hazardous and dangerous tasks. Among the components of a nuclear robot system, a robot control system equivalent to a human brain is a crucial point because a nuclear robot does not work without a control system. Therefore, in this paper, we will explain the requirements for a robot control system for a nuclear robot from a general point of view and also review the robot control systems of nuclear robots that were developed domestically, to assist a researcher beginning with the design for the control system of nuclear robots. The explained robot control system will be useful to develop the control system for industrial robots, home robots and other robots which are needed for tele-operation and are controlled through the internet.