• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.55 no.6
• /
• pp.227-235
• /
• 2006

In this paper, autonomous separation methodology of faulted section based on network is proposed newly, which can minimize the outage effect as compared with the existing center-based faulted section separation method by determining and separating autonomously the faulted section by the free operation information exchange among IEDs on the feeder of distribution system. The all IEDs is designed in network in which client/server function is possible in order to separate autonomously the faulted section using PtP(Peer to Peer) communication. Also, Inference based solution of IED for the autonomous faulted section separation is designed by rules obtained from the analyzing results of distribution system topology. Here, the switch IEDs transmit on network the fault information utilizing on multi-casting communication method, at the fame time, determine selfly whether they operates or not by inferencing autonomously the faulted section using the inference-based solution after receiving the transmitted information. Finally, in order to verify the effectiveness and application possibility of the proposed methodology, the diversity fault cases are simulated for the typical distribution system.

• Journal of Positioning, Navigation, and Timing
• /
• v.10 no.1
• /
• pp.21-28
• /
• 2021

In order to develop a Korea Positioning System (KPS) as part of key national infrastructure, independent navigation signal design is essential. The designed signal candidates must coexist with existing or planned GNSS signals within the limited frequency band. This requires a RF compatibility assessment, which can be performed using the Spectral Separation Coefficient (SSC) and Effective Carrier to Noise Density Ratio (Effective C/N0), for navigation signals. Thus, in this paper, the analysis of RF compatibility between the designed signal candidates and the existing GNSS signals is carried out based on analytical and numerical techniques.

• Journal of Aerospace System Engineering
• /
• v.7 no.3
• /
• pp.20-25
• /
• 2013

In case of cube satellite, it is difficult to realize the same performance as commercial satellite due to its highly restricted unit accommodation space. To maximize the performance of the cube satellite, design concept considering the multi-function of satellite is required. In this paper, mechanism design of cube satellite which is applicable for the holding and release of multi-deployable structures has been proposed and investigated. In addition, a switch mechanism design for the autonomous system operation just after the cube satellite separation from P-POD has also been proposed. The effectiveness of the mechanism design for holding and release of multi-deployable structures has been demonstrated by EM test of the holding and release mechanism.

• Journal of Advanced Navigation Technology
• /
• v.16 no.1
• /
• pp.122-130
• /
• 2012

Airborne separation assurance is a key requirement for Free Flight. This paper is to propose autonomous flight algorithm, such as extended authority of delegation, efficiency of airspace issue to deal with the empirical solution for free flight, and to measure flight efficiency and conflict detection and resolution (CD&R) by utilizing flight performance data under the two circumstances of scenario with the modeling of proposed algorithm and potential field algorithm. The results show that the autonomous flight algorithm is superior to the potential field algorithm under the circumstances of free flight airspace in terms of algorithm performance, CD&R, and flight efficiency.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.5 no.4
• /
• pp.243-248
• /
• 2005

The UAV (Unmanned Aerial Vehicle) systems like unmanned autonomous helicopters are used in various missions of flight navigation and used to collect the environmental information of the surroundings. To realize the full functionalities of the UAV, the software part becomes a challenging problem. In this paper embedded real-time software architecture for unmanned autonomous helicopter is proposed that guarantee real-time performance of hard-real time tasks and re-configurability of soft-real time and non-real time tasks. The proposed software architecture has four layers: hardware, execution, service agent and remote user interface layer according to the reactiveness level for external events. In addition, the layered separation of concurrent tasks makes different kinds of mission reconfiguration possible in the system. An Unmanned autonomous helicopter system was implemented (Kyosho RC Helicopter) in our lab to test and evaluate the performance of the proposed system.

• Journal of applied mathematics & informatics
• /
• v.39 no.3_4
• /
• pp.251-257
• /
• 2021

This article is devoted to introduce the notion of fuzzy cleanly covered fuzzy topological spaces; in addition two strong fuzzy separation axioms are studied. By means of fuzzy maximal open sets some properties of fuzzy cleanly covered fuzzy topological spaces are obtained and also by means of fuzzy maximal closed sets few identical results of a fuzzy topological spaces are investigated. Through fuzzy minimal open and fuzzy maximal closed sets, two strong fuzzy separation axioms are discussed.

• ETRI Journal
• /
• v.43 no.4
• /
• pp.702-716
• /
• 2021

This work proposes suitable network configurations for single frequency networks (SFNs) with ATSC 1.0 based on network coverage calculations and the laboratory multipath handling performance of commercial receivers. SFNs are widely used for delivering terrestrial digital television services because of their efficient use of the spectrum. In Mexico the analogue television transmissions switch-off occurred on 31 December 2016. Thus it is expected the adopted ATSC 1.0 system will be in force for the next several years despite the recent standardization of the ATSC 3.0 system. As ATSC 1.0 uses 8-VSB modulation the multipath handling capability of receivers is critical for the design of SFNs. The presented network planning results help develop technical normativity for implementing SFNs in Mexico and other countries that use ATSC 1.0. SFNs with transmitter separation up to 130 km are fully covered for outdoor reception mainly due to the directivity of the receiving antenna. Moreover for indoor reception at least 70% of an SFN coverage area can be achieved with a transmitter separation of up to 60 km depending on the radiated power and the transmitter antenna height.

• Journal of Advanced Navigation Technology
• /
• v.24 no.3
• /
• pp.192-197
• /
• 2020

Recently, the technologies related to autonomous drive has studying the goal for safe operation and prevent accidents of vehicles. There is radar and camera technologies has used to detect obstacles in these autonomous vehicle research. Now a day, the method for using LiDAR sensor has considering to detect nearby objects and accurately measure the separation distance in the autonomous navigation. It is calculates the distance by recognizing the time differences between the reflected beams and it allows precise distance measurements. But it also has the disadvantage that the recognition rate of object in the atmospheric environment can be reduced. In this paper, point cloud data by triangular functions and Line Regression model are used to implement measurement algorithm, that has improved detecting objects in real time and reduce the error of measuring separation distances based on improved reliability of raw data from LiDAR sensor. It has verified that the range of object detection errors can be improved by using the Python imaging library.

• Journal of Advanced Navigation Technology
• /
• v.16 no.2
• /
• pp.197-203
• /
• 2012

In this paper, study the substantial issues which occurs upon free flight environment by performing separation assurance under multiple conflict(over 3 Aircraft), recovery en route under the terms of time constrains and fixed way point after the conflict avoidance, correlations between conflict detection distance and separation assurance by utilizing Autonomous flight algorithm. Result of this experiment demonstrates that the extension of detection distance is advantageous to solution of separation assurance and enhancing of flight efficiency, choose to maneuver by applying time constrain terms and fixed way point according to the situation of conflict prediction in case of recovery maneuver after the conflict avoidance. And separation assurance can be solved by applying 2 degrees or more of bank angle. When choosing the optimal bank angle could be drastically improved flight efficiency.

• Journal of the Society of Naval Architects of Korea
• /
• v.60 no.5
• /
• pp.351-357
• /
• 2023

In this study, we devised methods to enhance the efficiency of rotor sails which have been applied as one of the energy saving devices of ships. The idea of the study originated from the notion that installing protrusions or increasing the surface roughness on the smooth surface of the rotor sail could delay the separation of the incoming wind flow and consequently increase the lift force. Five cylinder models were considered and tested in an open-type wind tunnel at Chungnam National University. A smooth surface cylinder exhibits the highest lift-to-drag ratio at a specific Reynolds number, and as the Reynolds number increases this value decreases sharply. The variation in this typical Magnus force can be significantly improved by altering the surface shape and roughness of the rotor sail. It has been observed that increasing the surface roughness improves the lift characteristics, resulting in increased efficiency. Furthermore, it revealed that the reverse Magnus effect which may occur during actual operation in the low spin ratio region can be significantly enhanced.