• Journal of Institute of Control, Robotics and Systems
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• v.16 no.3
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• pp.207-214
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• 2010

This paper proposes about decentralized control approach based Leader-Follower formation control using LOS (Line of Sight) algorithm and unknown input observer. The position of robots which is a basic information in multi-robot or single robot motion control is determined by localization algorithm fusing UPS (Ultrasonic Position System) and kinematics model. For formation control, a decentralized control approach individually installing a local controller in leader and follower robot is adopted. Leader robot is controlled to track a specified trajectory by LOS algorithm, and the other robots follow the leader by local controller based on tracking platoon level function, self-sensing data and estimated information from unknown input observer. The performance of proposed method is proven through the formation experiment of two vehicle models.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.1
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• pp.31-41
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• 2008

This paper deals with the energy saving problem of the follower aircraft in the loose leader-follower formation geometry in which the lateral separation between formation members is more than a wingspan of the leader aircraft. This formation geometry offers no drag benefit, but has a strategic advantage. In the case of loose formation flight, the follower aircraft usually consumes more energy than the leader aircraft because the follower aircraft should use more thrust to maintain given formation geometry, especially during the turning phase from the outside of the leader"s flight path or join-up phase. A formation control scheme based on the energy maneuverability is proposed in this paper. To design the proposed control law, the velocity command is designed using feedback linearization for the horizontal formation geometry and then coverts it to the altitude command using the energy equation. Numerical simulation is performed to verify the effectiveness of the proposed controller.

• Asia Marketing Journal
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• v.24 no.4
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• pp.178-189
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• 2023

As the necessity of customer relationship management (CRM) increases, measuring the performance of CRM have been actively discussed. Customer equity (CE) is regarded as an appropriate indicator for evaluating the outcomes of marketing activities. There are three drivers of CE: brand, value, and relationship equity. This study aims to investigate the impact of three drivers on customer satisfaction. Market competition is an environmental factor that affects the effectiveness of CRM. This study divides target firms into leaders and followers. This study found that the differential impact of CE drivers on customer satisfaction depends on the firm's status (leader or follower). Specifically, the brand equity driver significantly impacts the leader firm. However, the impacts of value and relationship equity drivers are bigger for follower firms. The above results suggest that firms need to build CRM strategies that consider the competitive situation of the market and their position.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1032-1040
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• 2012

This paper proposes controller of leader robot considering following robot with input constraints based on leader-following approach. In the previous formation control researches, it was assumed that leader and follower is same object. If leader robot drives as maximum speed that the initial position errors still remain even if following robot have same velocity as a leader. In the situation that velocity of following robot is lower than its leader robot, following robot cannot follow leader robot. Furthermore, the following robot will not be able to made formation with leader robot and keep proximity communication or sensing range. Therefore, multiple mobile robot system using leader-following method should be guaranteed range to get information each other. In this paper, Leader robot is driving to goal position using linear controller and following robot is following trajectory to be made from leader robot. We assume that following robot has input constraints to realize different performance between leader robot and following robot. We design controller of leader robot for desired goal position including the errors between formation and following robot. Thus, we propose leader robot controller considering input constraints of following robot. Finally, we were able to confirm the validity of the proposed method based on simulation results.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.818-829
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• 2003

A cooperating control algorithm for two nonholonomic mobile robots is proposed. The task is composed of collision avoidance against obstacles and carrying a ladder. The front robot and the rear robot are called the leader and the follower, respectively. Each robot has a nonholonomic constraint so it cannot move in perpendicular directions. The environment is initially supposed to be unknown except target position. The torque that drives leader is determined by distance between the leader and the target position or the distance between it and the obstacles. The torque by target is attractive and the torque by obstacles is repulsive. The two mobile robots are supposed to be connected by link that can be expanded and contracted. The follower computes its torque using position and orientation information from the leader by communication. Simulation results show that the robots can drive to target position without colliding into the obstacles and maintain the distance in the allowable range.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.602-608
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• 2015

In this paper, the limited error tracking problem is investigated for distributed leader-following wireless sensor networks (LFWSNs), where all sensors share data by the local communications, follower sensors are influenced by leader sensors directly or indirectly, but not vice versa, all sensor nodes track a reference state that is determined by the states of all leader sensors, and tracking errors are limited. In a LFWSN, the communicating graph is mainly expressed by some complete subgraphs; if we fix subgraphs that are composed of all leaders while all nodes in complete subgraphs of followers run on the sleeping-awaking method, then the fixed leaders and varying followers topology is obtained, and the switching topology is expressed by a Markov chain. It is supposed that the measurements of all sensors are corrupted by additive noises. Accordingly, the limited error tracking protocol is proposed. Based on the theory of asymptotic boundedness in mean square, it is shown that LFWSN keeps the limited error tracking under the designed protocol.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.2
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• pp.121-127
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• 2011

This paper presents an autonomous formation flight algorithm for micro aerial vehicles (MAVs) and its flight test results. Since MAVs have severe limits on the payload and flight time, formation of MAVs can help alleviate the mission load of each MAV by sharing the tasks or coverage areas. The proposed formation guidance law is designed using nonlinear dynamic inversion method based on 'Leader-Follower' formation geometric relationship. The sensing of other vehicles in a formation is achieved by sharing the vehicles' states using a high-speed radio data link. the designed formation law was simulated with flight data of MAV to verify its robustness against sensor noises. A series of test flights were performed to validate the proposed formation guidance law. The test result shows that the proposed formation flight algorithm with inter-communication is feasible and yields satisfactory results.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.943-956
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• 2020

In this study, the motion control problem of the vessel towed by a towing ship (tugboat) is considered. The non-powered towed ship is dragged by the towing ship. Even though the towed ship is equipped with propulsion systems, they cannot be used at low or constant speeds due to safety issues. In narrow canals, rivers, and busy harbor areas especially, where extreme tension is required during towing operation, the course stability of the towed vessel depends on the towing ship. Therefore, the authors propose a new control strategy in which the rudder system of the towed vessel is activated to provide its maneuverability. Based on the leader-follower system configuration, a nonlinear mathematical model is derived and a back-stepping control is designed. By simulation and experiment results with a comparison study, the usefulness and effectiveness of the proposed strategy are validated.

• (The)Study of the Eastern Classic
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• no.32
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• pp.363-390
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• 2008

In this article, the author studied the relationship between the Sovereign and the follower in Juyeok which contained some eliments, such as Eum-Yang, Soseong 8 gyae, Daeseong 64 gyae. In Juyeok, the 'Sovereign 5 hyo' (1) shows distinctiveness in basic characteristics whether they are Eum or Yang(high level classification), (2) shows characteristics of Soseong-gyae to which they belong(middle level classification), (3) shows different characteristics according to Daeseong-gyae's circumstances(low level classification). Five Yanghyo are regarded as male sovereign having masculinity, whereas five Eumhyo are female sovereign with femininity. Gungyae is the most 'sturdy type leader' who possesses dignity and has good judgement. Taegyae, the blessing type leader, holds affection and calmness within sturdiness. Rigyae is gorgeous and passionate 'enthusiastic type leader'. Jingyae, the pioneering leader, bravely starts ascending in Eum-dominant atmosphere. Songyae has the virtue of hesitancy and concession, known as the leader of humbleness. Gamgyae always stay low and calm, regarded as a leader of sense. Gangyae shoots up from the earth, meaning a leader of strong will. Gongyae, embracing type leader, is straight and square, though it tries to embrace everything. Daeseong-gyae(64gyae) is formed by Soseong-gyae piling another Soseong-gyae. The characteristics of Soseong 8gyae are embodied in two-level form, the top(inner gyae) and the bottom(outer gyae). Simultaneously, the whole characteristics of 대성괘 are embodied. The Sovereign should show his/her leadership based on the 'characteristics of Daeseong-gyae'. These characteristics are the contingency from 'contingency leadership'. In other words, they are preconditions which leaders ought to admit.

• International Area Studies Review
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• v.12 no.2
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• pp.99-123
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• 2008

In this paper, technology gap between Korea's manufacturing industries compared to technology frontier countries was estimated in order to take into account Korea's status as a technology follower country. Then by using this measure the role of technology gap was investigated in explaining total factor productivity growth of the Korean manufacturing at industry level. The main empirical findings are as follows: First, the conventional factors that were emphasized in the previous literature such as R&D intensity, trade openness and human capital play important role in explaining the growth rate of Korea's total factor productivity. Second, the larger the technology gap between Korea and technology leader country (and the faster the technology growth rate in the leader country), the higher the growth rate of total factor productivity in Korea as well. Third when the technology gap is large, the most efficient way of absorbing higher technology from frontier country seems to be the international trade channel rather than R&D or human capital accumulation.