• Journal of Internet of Things and Convergence
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• v.9 no.6
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• pp.37-44
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• 2023

As a primary technology of Industry 4.0, human-robot collaboration (HRC) requires additional measures to ensure worker safety. Previous studies on avoiding collisions between collaborative robots and workers mainly detect collisions based on sensors and cameras attached to the robot. This method requires complex algorithms to continuously track robots, people, and objects and has the disadvantage of not being able to respond quickly to changes in the work environment. The present study was conducted to implement a web-based platform that manages collaborative robots by recognizing the emotions of workers - specifically their perception of danger - in the collaborative process. To this end, we developed a web-based application that collects and stores emotion-related brain waves via a wearable device; a deep-learning model that extracts and classifies the characteristics of neutral, positive, and negative emotions; and an Internet-of-things (IoT) interface program that controls motor operation according to classified emotions. We conducted a comparative analysis of our system's performance using a public open dataset and a dataset collected through actual measurement, achieving validation accuracies of 96.8% and 70.7%, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.8
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• pp.688-695
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• 2014

In a small wireless environment, such as your home or office, a various network using WiMedia PHY can be mixed. Because these networks operate independently for each application, data conflict can occur between adjacent networks. To avoid data conflict, the resource in a different time zone can be utilized. However, if devices in a network increase, available resources in the network decrease, and then the lack of resources necessary to provide service can occur. To solve this problem, we propose collision avoidacne scheme for coexistence of various UWB systems. In this paper, we evaluate the performance of the proposed scheme through simulation.

• Journal of the Korea Society for Simulation
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• v.20 no.4
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• pp.59-66
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• 2011

This work presents an algorithm for generating multi-RUN (m-RUN) deadlock avoidance policy based on simulated annealing algorithm. The basic idea of this method is to gradually improve the current m-RUN DAP after constructing an initial m-DAP by using simple m RUN DAPs. The search for a neighbor of the current m-RUN DAP is done by selecting and changing only one component of the current m-RUN, while accepting some unimproved solutions with some probability. It is examined for its performance by generating some sample system configurations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.321-328
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• 2010

This paper presents a coordinator-based TDMA reader protocol that can avoid the reader collision in a passive RFID system. In the proposed protocol, the coordinator can not only minimize the number of empty slots by efficiently allocating slots to readers incoming in Poisson distribution, but reduce latency time through the limited frame size. The proposed protocol can be implemented in either mobile or fixed mode through the slot structure to be described in the context. The simulation results show it works as suggested and the frame size limitation as well as the statistical distribution of incoming readers has a great impact on the overall slots and the average latency time.

• Journal of IKEEE
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• v.25 no.2
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• pp.337-343
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• 2021

Deep reinforcement learning is an artificial intelligence algorithm that enables learners to select optimal behavior based on raw and, high-dimensional input data. A lot of research using this is being conducted to create an optimal movement path of a mobile robot in an environment in which obstacles exist. In this paper, we selected the Dueling Double DQN (D3QN) algorithm that uses the prioritized experience replay to create the moving path of mobile robot from the image of the complex surrounding environment. The virtual environment is implemented using Webots, a robot simulator, and through simulation, it is confirmed that the mobile robot grasped the position of the obstacle in real time and avoided it to reach the destination.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.1-9
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• 2010

In this paper, advanced evacuation analysis simulation on a passenger ship is performed. Velocity based model has been implemented and used to calculate the movement of the individual passengers under the evacuation situation. The age and gender of each passenger are considered as the factors of walking speed. Flocking algorithm is applied for the passenger's group behavior. Penalty walking velocity is introduced to avoid collision between the passengers and obstacles, and to prevent the position overlap among passengers. Application of flocking algorithm and penalty walking velocity to evacuation simulation is verified through implementation of the 11 test problems in IMO (International Maritime Organization) MSC (Maritime Safety Committee) Circulation 1238.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.616-619
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• 2012

When multiple Tags transmit their IDs to the Reader, tag identification time is delayed due to collisions. Therefore, to reduce the reader's identification time, an efficient anti-collision technology is needed. In this paper, a new anti-collision method is proposed. The method estimates the number of tags and allocates proper number of slots based on the DFSA. The performance of proposed method is compared with existing methods through extensive simulations.

• Electronics and Telecommunications Trends
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• v.32 no.4
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• pp.78-88
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• 2017

무인기의 기술 발전에 따른 운송, 통신중계, 교통감시, 산불감시 진화, 재해 재난대처 등 무인기의 민간 및 공공 수요가 확대되고 있다. 무인기는 국가 공역으로의 운항이 요구되는데, 국가 공역으로의 안전한 진입을 위해서는 유인항공기 조종사에 의한 시각 감지 및 회피와 동일할 수준의 안전성을 제공하는 탐지 회피 능력과 함께 신뢰성 높은 무인기 제어용 통신링크 확보가 필수적으로 요구되고 있다. 따라서, 본고에서는 국외 기술 개발 및 표준화 동향을 바탕으로 국가 공역에서의 무인기의 안정적 진입을 위해 필요한 무인기 지상 제어용 통신 및 네트워크 기술에 대해 살펴보고자 한다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.103-111
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• 1999

ATM 망의 혼잡상태를 회피하기 위하여 다양한 방법들이 제안되고 있으며, 이들 중에는 전송시스템에 존재하는 스위치의 버퍼 값에 지능형 마킹을 표시함으로서 각 전송회선에 공평한 대역폭을 할당하며 혼잡상태를 회피하는 방법이 있다 ATM Forum은 ATM 망에서 ABR 서비스의 혼잡제어를 위한 표준으로서 셀률 기반 혼잡제어기법을 적용하고 있다. EPRCA(Enhanced Proprotional Rate Control Algorithm)은 망의 상태를 항상 검사하는 것이 아니라 망의 혼잡이 발생하였을 때만 작동하기 때문에 부정확한 셀률 정보를 가질 수 있다. DMRCA(Dynamic Max Rate Control Algorithm)은 혼잡의 정도에 따라서 적절한 셀률을 부여하기 위하여 스위치에 임계값을 지정하며, 셀률은 스위치에서 제공되는 증가계수와 감소계수에 비례하여 변하게 된다. 본 논문은 DMRCA에서 혼잡제어를 위해서 적용하는 증가/감소변수의 크기 변화에 따른 공평대역할당의 수렴속도를 평가하여 최적의 변수값을 찾고자 한다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.47-53
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• 2018

In this paper, we investigate a collision avoidance algorithm for unmanned aerial vehicles using potential field based on the relative velocity of obstacles. The potential field consists of the attraction force and the repulsive force that are generated for the target and the obstacles. And the field can be classified into the attractive potential field generated by the target and the repulsive potential field generated by the obstacle, respectively. In this study, we construct an attractive potential field as a function of the distance between the UAV and the target position. On the other hand, a repulsive potential field is created by a function of distance and the relative velocity of the obstacle with respect to the UAV. The proposed potential field based collision avoidance algorithm is evaluate through simulations.