• 해양환경안전학회지
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• 제25권3호
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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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• 제4권1_2호
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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.

• 한국ITS학회 논문지
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• 제19권6호
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• pp.222-234
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• 2020

자율주행차는 GPS 및 레이더, 라이다, 카메라, IMU 등 다수의 센서가 장착되어 도심 교차로 주행 환경에서 다양한 교통체계를 인지하고 판단하여 주행하지만 장착된 센서의 감지 거리를 벗어나는 영역에 대한 예측 및 판단의 한계 등으로 자율주행차의 교차로 사고 비율은 전체 사고의 88%로 사고 비율이 높다. 따라서 ITS 도입으로 V2V, V2I를 통한 비신호 교차로 사고 회피 전략 연구가 진행되고 있을 뿐만 아니라 고장 상황에서 안전한 교차로 주행에 대한 연구도 진행되고 있지만 단순한 교차로 시나리오를 통한 검증과 단편적인 V2V 고장만을 제시하고 있다. 본 논문에서는 V2V 모듈의 아키텍쳐를 분석하여 V2V 모듈별 위험 요인을 분석하여 고장모드를 정의하였다. 또한 다양한 도로 조건 및 교통량에 따라 교차로 시나리오를 제시하여 ISO-26262 Part3 프로세스를 활용하여 HARA를 수행하여 자율주행차의 오작동에 대해 시뮬레이션 기반 위험성을 분석하여 ASIL을 제시하였다. V2V 모듈의 각 컴포넌트별 모니터링 컨셉을 제안하였고 시뮬레이션을 통해 모니터링 커버리지를 제시하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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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.

• 한국IT서비스학회지
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• 제10권1호
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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.

• 농촌지도와개발
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• 제7권1호
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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.

• 한국가정과교육학회지
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• 제33권3호
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• pp.65-84
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• 2021

이 연구는 중학생을 대상으로 가정교과의 '건강한 가족 관계' 수업을 디자인씽킹을 기반으로 프로그램을 개발하여 실행한 후 그 결과 중학생의 공감능력 향상에 유의미한 차이가 나타나는지 알아보는 데 목적이 있다. 이를 위해 디자인씽킹에 기반 한 총 5차시의 『슬기로운 '집콕'생활』프로그램을 개발하여 중학교 2학년 남녀 학생들을 대상으로 실행한 후, 사전-사후 검사를 통해 수업 후에 학생들의 공감능력이 향상되었는지 알아보았다. 그 결과, 『슬기로운 '집콕'생활』 프로그램은 중학생의 인지적 공감능력 향상에 유의미한 영향을 미친 것으로 나타났다. 또한 학생들의 수업에 대한 만족도는 전반적으로 긍정적이었다. 특히, 인스타그램으로 공감하기, '부캐' 만들기 등의 활동이 흥미로웠다는 의견이 많았다. 다만, COVID-19로 인한 시간의 부족 및 모둠활동 제약으로 인해 수업 활동에 어려움을 겪었다는 의견도 있었다. 이 연구는 COVID-19로 인해 학습 환경이 변화되는 상황에 유연하게 대처하기 위해 대면과 비대면 상황에 맞추어 활용할 수 있도록 프로그램을 개발하였다는 점과 가정과교육이 중학생의 공감능력 향상에 긍정적인 영향을 미치며, 특히 공감의 인지적 요인 향상에 도움을 준다는 점을 확인한 것에 그 의의가 있다.