• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.145-150
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• 2006

The paper deals with integrated navigation and sense & avoid systems for small unmanned aerial vehicles (UAV). First an introduction to the current UAV activities of the institute is given. It is followed by an overview about the integrated navigation system developed for small UAVs. The system is based on a tightly-coupled GPS/INS architecture. But instead of using delta-ranges, time-differenced carrier phases are used to aid the INS. Finally, results from navigation filter validation in flight tests are presented. After that an overview about sense and avoid strategies for application in small unmanned aircraft is given. From this a guideline for developing such a system for the institute's UAVs is presented.

• 한국항공운항학회지
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• 제25권4호
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• pp.83-90
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• 2017

Unmanned Aerial Vehicles(UAVs) require collision avoidance capabilities equivalent to the capabilities of manned aircraft to enter the airspace of manned aircraft. In the case of Visual Flight Rules of manned aircraft, collision avoidance is performed by 'See-and-Avoid' of pilots. To obtain those capabilities of UAVs named as 'Sense-and-Avoid', sensor-system-based intruder tracking and collision avoidance methods are required. In this study, a multi-sensor-based tracking, data fusion, and collision avoidance algorithm is designed by using a model-based design tool MATLAB/SIMULINK, and validations of the designed model and code using numerical simulations and processor-in-the-loop simulations are performed.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.565-568
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• 2004

Facilities Sharing is defined as the access providers who is holding the telecommunications facilities rent their facilities to the access seekers who is not holding them to promote the fair competition among carriers in a narrow sense and to avoid the duplication of investment in a broad sense. MIC, the regulator in Korea, has revised the current policy of facilities access toward mandatory system. The purpose of this paper is to review the pricing principle of facilities sharing in major countries and to discuss the implications of this case study.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4617-4632
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• 2021

IEEE 802.11ax is a protocol being developed for high-density Wireless Local Area Networks (WLAN). Several algorithms have been proposed to improve the level of spatial reuse applied in IEEE 802.11ax. However, these algorithms are tentative and do not specify how to select the transmit power and carrier sense threshold in practice; It is unclear when and why the tuned parameters lead to better network performance. In this paper, we restricted the scale of transmit power tuning to prevent the case of backfire in which spatial reuse will result in transmission failure. If the restrictions cannot be satisfied, spatial reuse will be abandoned. This is why we named the proposed scheme as Arbitration based Spatial Reuse (ASR). We quantified the network performance after spatial reuse, and formulate a corresponding maximum problem whose solution is the optimal carrier sense threshold and transmit power. We verified our theoretical analysis by simulation and compared it with previous studies, and the results show that ASR improves the throughput up to 8.6% compared with 802.11ax. ASR can avoid failure of spatial reuse, while the spatial reuse failure rate of existing schemes can up to 36%. To use the ASR scheme in practice, we investigate the relation between the optimal carrier sense threshold and transmit power. Based on the relations got from ASR, the proposed Relation based Spatial Reuse (RSR) scheme can get a satisfactory performance by using only the interference perceived and the previously found relations.

• International Journal of Advanced Culture Technology
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• 제11권1호
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• pp.221-231
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• 2023

Nowadays, more and more countries are paying attention to basic teaching, so it can be found that they are carrying out a new round of basic teaching reform. The fundamental purpose is to adapt to the economic, cultural and technological development of the 21st century, so that their nationals will not be eliminated in the competition of the world environment, the spiritual civilization and material life of the nationals can be further improved, and they can have an advantage in the competition and catch up with the advanced level of the world. The cultivation of preschoolers' mental health determines the future development of a person. Through the long-term practice of art teaching at the Longyuan Branch of the District Third Kindergarten of Guangxi, This paper summarizes some effective teaching methods to cultivate children's connection ability and sense of security through aesthetic education.Firstly, preschoolers' contact ability was studied, and the aspects such as the definition of contact ability and the reasons for the formation of contact ability were explored. Secondly, the development of preschoolers' sense of security, what to avoid in order to develop a good sense of security and the effects of security on children were investigated. Finally, several specific teaching cases were written based on these theories. Through these cases, aesthetic education was utilized to promote preschoolers' contact ability and develop a sense of security. The study mainly draws the following conclusions that if children want to have a successful career, a happy family in the future, it is crucial to have the ability of connect and security in childhood. Aesthetic education can promote the formation of children's ability of connection and security.Finally, I write specific teaching cases based on the above theories and practice, through which these cases use aesthetic education to promote the formation of children's contact ability and sense of security.

• 한국정보통신학회논문지
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• 제10권6호
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• pp.1060-1064
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• 2006

센서를 통해 수집된 데이터는 모든 정보를 취합하는 기지국으로 전송되게 된다. 센서들은 데이터를 전송하면서 지속적으로 주변 환경에 대한 데이터를 수집하여야 하기 때문에 에너지 소모가 크다. 본 논문에서는 수집된 데이터가 효율적으로 전송되어 트래픽 혼잡을 피하면서 에너지 효율성을 고려하는 기법을 제안한다. 트래픽이 증가하거나 감소할 때 전송률을 제어함으로써 Traffic 혼잡을 피하고, 기본적인 CSMA(Carrier Sense Multiple Access) 프로토콜에 최적의 옵션을 설정하여 각 센서에서 에너지 소모를 최소화는 기법이다. 시뮬레이션을 통해 최적의 CSMA 옵션과 제안된 트래픽 제어 기법을 적용하여 성능을 분석하고, 에너지 효율성과 효과적인 트래픽 제어 방법을 제시한다.

• Journal of applied mathematics & informatics
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• 제6권3호
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• pp.823-834
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• 1999

The present paper deals with the problem of nonselective harvesting in a partly infecte prey and predator system in which both the suseptible prey and the predator follow the law of logistic growth and some preys avoid predation by hiding. The dynamical behaviour of the system has been studied in both the local and global sense. The optimal policy of exploitation has been derived by using Pontraygin's maximal principle. Numerical analysis and computer simulation of the results have been performed to inverstigate the global properties of the system.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.49-52
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• 2003

IEEE 802.11 MAC uses a distributed coordination function (DCF) known as carrier sense multiple access with collision avoidance (CSMA/CA) for medium access. Random back-off algorithm helps to avoid the collision. This paper proposes virtual back-off and modified back-off algorithm for reduce a waiting time by back-off and reduce the collision. The modified DCF is consisted of these two algorithms. We expect to reduce the average waiting time of each transmission by using the modified DCF algorithm.

• 한국항행학회논문지
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• 제19권4호
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• pp.288-298
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• 2015

무인기 상용화를 위해서는 유인기 수준의 안전성을 확보할 수 있는 공중 및 지상 의 충돌경보 및 회피시스템 (sense and avoid or SAA) 개발과 검증이 필요하다. SAA 검증을 위한 비행시험은 높은 시험비용과 사고위험 때문에 많은 시험사례(test case)를 검토하기 어려우므로 시뮬레이션 시험으로 보완하는 것이 필수적이다. SAA 시뮬레이션 시험을 위해 flight simulator, Matlab/Simulink 시뮬레이터와 항전장비 시뮬레이션 모델들이 서로 연동하는 통합 무인기 시뮬레이션 환경을 구축하였다. 사례연구로서 TCAS 충돌경보 simulink 모델을 개발하고 Flight Gear와 연동하여 통합 무인기 시뮬레이션 환경을 구축하였고 이를 encounter model을 이용하여 검증하였다. 통합 무인기 시뮬레이션 환경을 활용하면 항전장비 개발주기의 개념설계 단계부터 부품 및 시스템의 성능/신뢰성 분석을 시작할 수 있다.

• 수산해양교육연구
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• 제25권6호
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• pp.1294-1305
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• 2013

The aim of this study was to identify the attitude of nursing students' toward death using Q-methodology and to obtain baseline data to improve nursing students' education program on death. Twenty-nine participants at a college classified 40 Q-statements on a one to nine scale. The resultant Q-sort was a matrix representing the participant's operant subjectivity on the issue under consideration. The results of above procedures were analyzed by PQ Method. The results revealed that there are three types of perception about nursing students' attitudes toward the death. The categories were labeled positive-perspective, pain-avoid and preparation-deficiency. Positive-perspective individuals have a positive sense of their life and death. Thus, they would not fear death, believing in an after-life world, while being positive towards donation of intestines after death. Pain-avoid individuals hope life and death without pain. Preparation-deficiency individuals are unprepared to die. In conclusion, this study discovers three types of the perception about nursing students' attitudes toward the perception of death. By identifying the nature of each of these types, this study can be useful to develop efficient strategies for education program on death.