• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.3
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• pp.259-268
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• 2019

Even if only two ships are encountered, a collision may occur due to the mistaken judgment of the positional relationship. In other words, if an officer does not know a target ship's intention, there is always a risk of collision. In this paper, the experiments are conducted to investigate how the intention affects the action of collision avoidance in cooperative and non-cooperative situations. In non-cooperative situation, each ship chooses a course that minimizes costs based on the current situation. That is, it always performs a selfish selection. In a cooperative situation, the information is exchanged with a target ship and a course is selected based on this information. Each ship uses the Distributed Stochastic Search Algorithm so that a next-intended course can be selected by a certain probability and determines the course. In the experimental method, four virtual ships are set up to analyze the action of collision avoidance. Then, using the actual AIS data of eight ships in the strait of Dover, I compared and analyzed the action of collision avoidance in cooperative and non-cooperative situations. As a result of the experiment, the ships showed smooth trajectories in the cooperative situation, but the ship in the non-cooperative situation made frequent big changes to avoid a collision. In the case of the experiment using four ships, there was no collision in the cooperative situation regardless of the size of the safety domain, but a collision occurred between the ships when the size of the safety domain increased in cases of non-cooperation. In the case of experiments using eight ships, it was found that there are optimal parameters for collision avoidance. Also, it was possible to grasp the variation of the sailing distance and the costs according to the combination of the parameters, and it was confirmed that the setting of the parameters can have a great influence on collision avoidance among ships.

• Journal of Applied and Pure Mathematics
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• v.4 no.1_2
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• pp.27-36
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• 2022

An innovation diffusion model is proposed model consists of three classes, namely, a non-adopter class, adopter class innovation-I, and adopter class innovation-II in a partially competitive and cooperative market. The proposed model is analyzed with the help of the qualitative theory of a system of ordinary differential equations. Basic influence numbers associated with first and second innovation $R_{0_1}$ and $R_{0_2}$ respectively in the absence of each other are quantified. Then the overall basic influence number (R₀) of the system is assessed for analyzing stability in the market in different situations. Sensitivity analysis of basic influence numbers associated with first and second innovation in the absence of each other is carried out. Numerical simulation supports our analytical findings.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.222-234
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• 2020

Autonomous vehicles are equipped with a wide rage of sensors such as GPS, RADAR, LIDAR, camera, IMU, etc. and are driven by recognizing and judging various transportation systems at intersections in the city. The accident ratio of the intersection of the autonomous vehicles is 88% of all accidents due to the limitation of prediction and judgment of an area outside the sensing distance. Not only research on non-signalized intersection collision avoidance strategies through V2V and V2I is underway, but also research on safe intersection driving in failure situations is underway, but verification and fragments through simple intersection scenarios Only typical V2V failures are presented. In this paper, we analyzed the architecture of the V2V module, analyzed the causal factors for each V2V module, and defined the failure mode. We presented intersection scenarios for various road conditions and traffic volumes. we used the ISO-26262 Part3 Process and performed HARA (Hazard Analysis and Risk Assessment) to analyze the risk of autonomous vehicle based on the simulation. We presented ASIL, which is the result of risk analysis, proposed a monitoring concept for each component of the V2V module, and presented monitoring coverage.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3867-3886
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• 2015

This article investigates the problem of opportunistic spectrum access in dynamic environment, in which the signal-to-noise ratio (SNR) is time-varying. Different from existing work on continuous feedback, we consider more practical scenarios in which the transmitter receives an Acknowledgment (ACK) if the received SNR is larger than the required threshold, and otherwise a Non-Acknowledgment (NACK). That is, the feedback is discrete. Several applications with different threshold values are also considered in this work. The channel selection problem is formulated as a non-cooperative game, and subsequently it is proved to be a potential game, which has at least one pure strategy Nash equilibrium. Following this, a multi-agent Q-learning algorithm is proposed to converge to Nash equilibria of the game. Furthermore, opportunistic spectrum access with multiple discrete feedbacks is also investigated. Finally, the simulation results verify that the proposed multi-agent Q-learning algorithm is applicable to both situations with binary feedback and multiple discrete feedbacks.

• Journal of Information Technology Services
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• v.10 no.1
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• pp.177-190
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• 2011

Due to the growth of economy and the advancement of IT, the life expectancy has been prolonged and the interests in health have greatly increased. Recently the request for systems that enable measuring the bio-signals of patients in the non medical organizations, such as home, and transmitting them to medical staffs at remote sites for monitoring them. In this paper, we present an agent-based u-health system for patients or suspects with heart diseases. Our system consists of portable devices for measuring bio-signals and agents that perform data collection, data storage, automatic detection of abnormal status in patients, and HL7-based data exchange in a cooperative way. The main features of the system are : the agent-based architecture facilitates the addition of new service modules as well as the modification of existing ones; an intelligent agent is provided which automatically detects situations in which the bio-signals of patients are abnormal; the medical data standard is supported so that the communication with other systems is very easy. To our survey, there have been few previous systems which support all those features in a seamless way.

• Journal of Agricultural Extension & Community Development
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• v.7 no.1
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• pp.101-119
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• 2000

Agricultural Extension Services in Korea have accomplished a significant role in self- sufficiency of rice, a national staple food, through green revolution in 1970's; supplying green vegetables even during the winter season through white revolution in 1980's; and establishing technical agriculture by organizing rural leaders and 4-H members. In 1990s changes were made in international situations under the Uruguay Round multilateral trade negotiations and inauguration of the World Trade Organization. This was followed by localization of the extension staffs and the functions of extension services in Korea changed dramatically from national government to local governments. Thus, a weakened national function resulted in loosening of the linkages of research and extension in central government and local extension offices. Difficulties were reported in diffusion of new agricultural technology and efficient management of extension personnel. Developmental tasks for better extension services for the 21st century in Korea would include recovering national functions of agricultural extension, and developing a new paradigm for extension service. This should include the following measures; 1) Cooperative extension service should be adapted to involve national as well as local governments and non-government organization. 2) The target groups for extension services should be expanded to include farmers, noel residents as well as urban consumers. 3) The role of the extension service should cover agricultural technological diffusion of innovations as well as managerial skills and leadership development for rural organizations. 4) Extension services should be introduced to small farmers as well as consultation services for advanced farms. Diversified approaches should be employed for mama effective services. 5) Pre-service as well as in-service education should be offered to secure better extension educators equipped with knowledge, understanding and abilities on agricultural technology, information, agricultural philosophy, instructional methods and communication skills.

• Journal of Korean Home Economics Education Association
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• v.33 no.3
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• pp.65-84
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• 2021

In this study, a program was developed and implemented for middle school students in the 'Healthy Family Relations' of the home economics based on design thinking process. The purpose was to investigate whether a significant difference is displayed in terms of empathy ability improvement among middle school students. For this purpose, a "Wise 'stay-at-home' life" program comprised of five class sessions was developed based on design thinking process. The program was implemented to male and female students in the second year of middle school, and students' empathy ability was examined by a pre- and post-test comparison. As a result, the developed program was found to have generated a significant improvement in cognitive empathy among middle school students. In addition, the students' satisfaction with the class was generally positive. In particular, many students mentioned that they were interested in activities such as 'empathizing through Instagram' and 'creating a sub-character'. However, there also was an opinion that the lesson activities were difficult to complete due to the lack of time and restrictions on cooperative activities due to COVID-19. In this research, we developed a program that can be used in both face-to-face and non-face-to-face situations in order to flexibly deal with situations where the learning environment changes due to COVID-19. And this research is significant particularly in that it confirmed that home economics have a positive influence on improving middle school students' empathy ability, particularly the cognitive factor of empathy.