• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.5
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• pp.635-643
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• 2018

This paper propose a method to identify the motor parameters and improve input voltage error which affect the low speed position error of the back-emf(back electromotive force) based sensorless algorithm and to secure the operation reliability and stability even in the case where the load fluctuation is severe and the start and low speed operation frequently occurs. In the model-based observer used in this paper, stator resistance, inductance, and input voltage are particularly influential factors on low speed performance. Stator resistance can cause resistance value fluctuation which may occur in mass production process, and fluctuation of resistance value due to heat generated during operation. The inductance is influenced by the fluctuation due to the manufacturing dispersion and at a low speed where the change of the current is severe. In order to find stator resistance and inductance which have different initial values and fluctuate during operation and have a large influence on sensorless performance at low speed, they are commonly measured through 2-point calculation method by 2-step align current injection. The effect of voltage error is minimized by offsetting the voltage error. In addition, when the command voltage is used, it is difficult to estimate the back-emf due to the relatively large distortion voltage due to the dead time and the voltage drop of the power device. In this paper, we propose a simple circuit and method to detect the voltage by measuring the PWM(Pulse Width Modulation) pulse width and compensate the voltage drop of the power device with the table, thereby minimizing the position error due to the exact estimation of the back-emf at low speed. The suitability of the proposed algorithm is verified through experiment.

• Korean journal of communication and information
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• v.71
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• pp.116-154
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• 2015

Officially given a historical signifier as Gwangju Democratic Movement since 1987, far-right and conservative group have restated that $5{\cdot}18$ is a rebellion and a riot that was committed by rebellious elements who obeyed North Korea's command or who were connected with North Korea. As those who had been responsible for the rebellion, revolt and riot were rewarded, far-right and conservatives' collective narrative that a country was born where the pro-North Korea left became dominated aroused extreme hostility towards $5{\cdot}18$. Far-right and conservatives involved in many different fields such as political party, university, press and media and civil group carry out incendiary discourse politics with intention to reestablish history and memory of $5{\cdot}18$ in their own story. Many people at online sites such as Ilbe Storehouse who are considered 'young right wing' is a main route to spread the far-right groups' remarks on $5{\cdot}18$. Ilbe is a main channel to reconstitute and reproduce the far-right conservatives' remarks and information on $5{\cdot}18$. Ilbe is one of main area where remarks of disparagement and ridicule, hostility and hatred on $5{\cdot}18$ unfurl. This study collects $5{\cdot}18$-related remarks and stories unfolded at Ilbe and examines how these remarks and stories make significance as to $5{\cdot}18$ and how information resources which remarks are dependent upon are connected each other. In this process, this study intends to find implications of incendiary politics that echoed of remarks on $5{\cdot}18$ have which at the online site Ilbe and by the far-right conservatives.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.490-501
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• 2019

This study is aimed at researching Gyobang Dance performed by gisaeng of Gyobang in the banquet of Tonshinsa in Yeongnam Jwa-do Province. For this study, Hae-haeng-chong-che, a collection of 28 travel essays written by Joseon Tonshinsa after visiting Japan, and a collection of literary works were analyzed. Joseon Tonshinsa used Yeongnam Jwa-do Province as a route to Japan in obedience to a royal command, and Yeongnam U-do Province as a way back to Hanyang after completing their missions. The country gave a huge banquet to relieve Tonshinsa's anxiety about the voyage and to pray for a safe trip. The banquets were concentrated in Yeongnam Jwa-do Province, the way down to Busan departing from Hanyang. Looking into Tonshinsa's records, it can be seen that Tonshinsa banquets took place in Andong, Yeongcheon, Gyeongju, Milyang, and Busan. Gyobang Dance performed at Tonshinsa banquets includes Geommu, Hwangchangmu, Cheoyongmu, Cheondo, Mudong, Ipchum, and Jungchum. Through Tonshinsa envoy, 'Jeseon Tonshinsa-gil' was formed in Yeongnam Jwa-do Province, and through Tonshinsa banquets, the artistry of Gyobang Dance was compiled. Nevertheless, present Yeongnam Jwa-do Province has remarkably less Gyobang Dance passed down in comparison to Yeongnam U-do Province. For this reason, there is a need to look into Gyobang Dance of Yeongnam Jwa-do Province. The purpose of this study is to closely examine the cultural and artistic characteristics of Gyobang Dance performed at Tonshinsa banquets in Yeongnam Jwa-do Province formed through Joseon Tonshinsa-gil.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.591-598
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• 2021

One of the requirements of metro trains is to stop with precision to ensure that the train can stop precisely at the designated location on the platform. If this is not satisfied, interference with the screen door occurs, causing inconvenience to passengers and delays in operation. In the case of an automatic operated train, the current position is determined by the current speed information of the train, and control is performed by issuing an acceleration/deceleration command. Therefore, accurate control becomes impossible if the error of the speed information is large. In metro railroads, a Precision Stop Marker (PSM) is used to correct the position error, so that the error of stop control can be reduced by correcting the position error at a specific point. On the other hand, because the PSM itself has only position information, it does not compensate for the speed error. This paper proposes a method for performing in-place stop control by estimating the speed with the PSM progress information. The speed can be estimated when the train is operated at a constant deceleration speed, and the target deceleration can be obtained to perform stop control. The feasibility and excellence of the proposed method are shown through a numerical simulation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.363-375
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• 2013

Today, a shortage of the skilled operator has been intensified gradually and the necessity of an earthwork in extreme environment operators are difficult to access is increasing for the purpose of resource development and new living space creation. For this reason, an effort to develop an unmanned excavation robot for fully automated earthwork system is continuing globally. In Korea, a research consortium called 'Intelligent Excavation System' has been formed since 2006 as a part of Construction Technology Innovation Program of Ministry of Land, Transport and Maritime Affairs of Korea. Among detailed technologies of the Task Planning System is one of the core technologies of IES, this paper explains research and development process of the Local Area Design Module, which provides informatization unit to create automated excavators' work command information at operation level such as location, range, target, and sequence for excavation work. Designing of Local Area should be considered various influential factors such as excavator's specification, working mechanism, heuristics, and structural stability to create work plan guaranteed safety and effectiveness. For this research, conceptual and detail design of the Local Area is performed for analyzing design element and variable, and quantization method of design specification corresponding with heuristics and structural safety is generated. Finally, module is developed through constructed algorithm and developed module is verified.

• Journal of Korean Society of Transportation
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• v.24 no.1 s.87
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• pp.19-28
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• 2006

To develop a crisis management for aviation safety, this study has defined crisis management includes risk management which is eliminates or lowers risks prior to accidents and emergency response after the accidents. This study takes a look at different kinds of crisis managements, risk managements and statistical methods of other nations and fields in order to develop a risk management model. Through surveys which have 102 risk factors that include air traffic control, maintenance and airport sectors, the weight of each risk factor was calculated and the probability was divided to develop a model for risk management. The risk management model of this study is conducted using four steps (risk management plan, risk factor identification, weight and probability analysis, decision making) and 4 standards of weight along with 5 standards of probability This study takes a look at Predictions through a quantitative method using a risk index for the risk management model An effective risk management model should have a wide and continuous collection of data and adopt various methods using this model. The crisis management could not be very effective only using a pre-active risk management. So it should also be conducted by using a pro-active response system to protect additional damage and to prevent accidents of the same nature. From the results, the most important points were the establishment of command and control accountabilities, and cooperation of related organizations.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.1
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• pp.19-29
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• 2000

Because the previous simulation tool for attitude control of satellite was designed for the modeling of rigid body and PD controller, the attitude error can be made more than the limitation value for keeping for communication link, and then the communication link can be lost at moving of satellite. So, for rapid attitude restoration and design of stable and modernized controller, the modelling of rigid body and flexible body structure for moving GEO and LEO satellites were performed. Also the minimum time controller is designed for the rapid restoration of attitude error at communication broken and to minimize the disconnection period from ground communication system during the satellite stationkeeping. The linear regulator is designed using the space state vector that is better than accuracy and stability of PD controller. Firstly the simulation was performed for comparison of the rigid and stability of PD controller. Firstly the simulation was performed for comparison of the rigid and flexible models using PD controller and the case of the pitch angle changing by ground command, and the case of the periodic north-south stationkeeping are performed for the analysis of response characteristics of each controller when the attitude is changed. As a result, the flexible body model represents more sililar results of real situation than the rigid body model. The minimum time controller can restore 7 times rapidly than PD controller for its lost attitude. The linear regulator has several merits for capability of adaptation against the external disturbance, stability and response time. In future, we can check the estimated results using this satellite model and controller for real operation. Futhermore the development of new controller and training can be supported.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.3
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• pp.99-106
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• 2018

In the process of acquiring information through the cyber ISR (Intelligence Surveillance Reconnaissance) and research into the agent to help decision-making, periodic communication between the C&C (Command and Control) server and the agent may not be possible. In this case, we have studied how to effectively surveillance and reconnaissance. Due to the network configuration, agents planted on infiltrated computers can not communicate seamlessly with C&C servers. In this case, the agent continues to collect data continuously, and in order to analyze the collected data within a short time in When communication is possible with the C&C server, it can utilize limited resources and time to continue its mission without being discovered. This research shows the superiority of incremental learning method over batch method through experiments. At an experiment with the restricted memory of 500 mega bytes, incremental learning method shows 10 times decrease in learning time. But at an experiment with the reuse of incorrectly classified data, the required time for relearn takes twice more.

• Journal of Aerospace System Engineering
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• v.14 no.1
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• pp.68-73
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• 2020

This purpose of this paper was to review the development trend of the VTOL MAVs with a ducted propellant that can fly like the VTOL at intermediate and high speeds, hovering, landing, and lifting off vertically over urban areas, warships, bridges, and mountainous terrains. The MAV differs in flight characteristics from helicopters and fixed wings in many respects. In addition to enhancing thrust, the duct protects personnel from accidental contact with the spinning rotor. The purpose of the U.S. Army FCS and DARPA's OAV program is spurring development of a the VTOL ducted MAV. Today's MAVs are equipped with video/infrared cameras to hover-and-stare at enemies hidden behind forests and hills for approximately one hour surveillance and reconnaissance. Class-I is a VTOL ducted MAV developed in size and weight that individual soldiers can store in their backpacks. Class-II is the development of an organic VTOL ducted fan MAV with twice the operating time and a wider range of flight than Class-I. MAVs will need to develop to perch-and-stare technology for lengthy operation on the current hover-and-stare. The near future OAV's concept is to expand its mission capability and efficiency with a joint operation that automatically lifts-off, lands, refuels, and recharges on the vehicle's landing pad while the manned-unmanned ground vehicle is in operation. A ducted MAV needs the development of highly accurate relative position technology using low cost and small GPS for automatic lift-off and landing on the landing pad. There is also a need to develop a common command and control architecture that enables the cooperative operation of organisms between a VTOL ducted MAV and a manned-unmanned ground vehicle.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.263-267
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• 2015

current mine detector can't division the section if it is conducted and it needs too much labor force and time. in addition to, if the user don't move the head of sensor in regular speed or move it too fast, it is hard to detect a mine exactly. according to this, to improve the problem using one direction ultrasonic wave sensing signal, that is made up of human body antenna part, main micro processor unit part, smart glasses part, body equipped LCD monitor part, wireless data transmit part, belt type power supply part, black box type camera, Security Communication headset. the user can equip this at head, body, arm, waist and leg in removable type. so it is able to detect the powder in a 360-degree on(under) the ground whether it is metal or nonmetal and it can express the 2D or 3D film about distance, form and material of the mine. so the battle combats can avoid the mine and move fast. also, through the portable battery and twin self power supply system of the power supply part, combat troops can fight without extra recharge and we can monitoring the battle situation of distant place at the command center server on real-time. and then, it makes able to sharing the information of battle among battle combats one on one. as a result, the purpose of this study is researching a smart wearable mine detector which can establish a smart battle system as if the commander is in the site of the battle.