• Journal of the Korean Society of Earth Science Education
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• v.12 no.3
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• pp.184-197
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• 2019

The purpose of this study is to explore needs and the direction for the development of localization data in the geological field of elementary school. Many studies show that geology-related learning is highly effective in the form of direct learning, and It is reported that this learning has a positive effect on students' scientific attitudes. As such, the first-hand experience of the geological learning is outdoor geology learning and is the basis and core of the development of localization materials. However, the analysis of this study shows that the development of outdoor geology learning site is mainly conducted in some regions. In addition, considering that geological sites are distributed evenly throughout Korea, it is necessary to actively develop geological-related localization materials to learn elementary school geology-related units. In addition, some areas where outdoor geological study grounds were developed are composed only of learning places and no specific learning materials have been developed. In this regard, not only geological researchers but also field teachers working in the area need much effort. Development of localization material in the geological field needs to be developed at the level of material presented in the geology unit of the textbook. And in the actual class, it is desirable to use the textbook data and the developed localization data at the same time. In addition, the development of the outdoor geology field should be developed in consideration of the pre-experience-post activities so that learners can have various geological experiences.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.409-414
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• 2010

The applications based on geographical location are increasing rapidly in wireless sensor networks (WSN). Recently, various localization algorithms have been proposed but the majority of algorithms rely on the specific hardware to measure the distance from the signal sources. In this paper, we propose the Weighted Multiple Rings Localization(WMRL). We assume that each deployed anchor node may periodically emit the successive beacon signals of the different power level. Then, the beacon signals form the concentric rings depending on their emitted power level, theoretically. The proposed algorithm defines the different weighting factor based on the ratio of each radius of ring. Also, If a sensor node may listen, it can find the innermost ring of the propagated signal for each anchor node. Based on this information, the location of a sensor node is derived by a weighted sum of coordinates of the surrounding anchor nodes. Our proposed algorithm is fully distributed and does not require any additional hardwares and the unreliable distance indications such as RSSI and LQI. Nevertheless, the simulation results show that the WMRL with two rings twice outperforms centroid algorithm. In the case of WMRL with three rings, the accuracy is approximately equal to WCL(Weighted Centroid Localization).

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.2
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• pp.54-64
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• 2010

Localization is the most important feature in the sensor network environment because it is a basic element enabling people and things to aware the circumference environment. Existing localization methods can be categorized as either range-based or range-free. While range-based is known to be not suitable because of the irregularity of radio propagation and the additional device requirement. range-free is much appropriated for the resource constrained sensor network because it can actively locate by means of the communication radio. But its location accuracy is just depended on the density of circumference nodes; it is very low in low-density sensor network environment. This paper proposes a mobile object tracking method, named DRTS(Distributed Range-hybrid Tracking Scheme), with combining range-based and range-free. It is optimally making use of the location, communication range, and received signal strength from circumference nodes. Especially, it can greatly improve the mobile tracking accuracy by adapting a new prediction method, named EGP(Estimative Gird Points) into the proposed location estimation method. The simulation results show that our method outperforms the other localization and tracking methods in the tracking accuracy point of view.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1821-1822
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• 2007

무선 센서 네트워크에서 위치인식 기술은 데이터 수집, 라우팅, 위치기반 서비스와 같은 기술에 필수적인 기술이다. 본 논문에서는 베이즈 이론을 이용한 그리드방식의 분산형 위치 인식기술을 제안한다. 이 기법은 센서 노드들이 받은 신호세기를 바탕으로 하여 그리드를 구성해서 베이즈 이론을 이용하여 가장 큰 확률을 갖는 그리드를 자신의 위치로 인식하는 방식이다. 우리는 시뮬레이션을 통하여 기존의 방식보다 제안된 알고리즘이 정확한 위치를 갖으며, 더욱 효율적인 연산을 수행함을 알 수 있다.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.255-261
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• 2020

We consider the problem of autonomously flying a quadcopter in indoor environments. Navigation in indoor settings poses two major issues. First, real time recognition of the marker captured by the camera. Second, The combination of the distributed images is used to determine the position and orientation of the quadcopter in an indoor environment. We autonomously fly a miniature RC quadcopter in small known environments using an on-board camera as the only sensor. We use an algorithm that combines data-driven image classification with image-combine techniques on the images captured by the camera to achieve real 3D localization and navigation.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10b
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• pp.30-33
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• 2006

WSN에서 가장 요구되는 요소들 중 하나인 높은 scalability를 가지는 분산 시스템에서는 WSN의 센서 노드가 능력이 한정되어 있기 때문에, 구현 가능한 경량 알고리즘이 필요하다. Distributed Acoustic 위치판별(DSL) 시스템은 이러한 scalability와 노드 능력에 적합하게 설계되었다. 이벤트 영역은 이벤트를 감지하는 분산 시스템에서의 정확도와 알고리즘의 복잡도에 직결되기 때문에 그 중요성이 WSN에서 더욱 크지만 이 시스템은 이벤트 영역에 대한 고려가 존재하지 않았고, 따라서 DSL 시스템은 성능이 최적화 되지 못하였다. 우리는 DSL에 적합한 이벤트 영역을 정의하여 시스템의 성능을 향상시켰다.

• Journal of the Korea Society for Simulation
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• v.1 no.1
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• pp.64-76
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• 1992

The DEVS(discrete event system specificaition) formalism specifies a discrete event system in a hierarchical, modular form. DEVSIM++ is a C++based general purpose DEVS abstract simulator which can simulate systems modeled by the DEVS formalism in a sequential environment. This paper describes P-DEVSIM++which is a parallel version of DEVSIM++ . In P-DEVSIM++, the external and internal event of DEVS models can by processed in parallel. For such processing, we propose a parallel, distributed optimistic simulation algorithm based on the Time Warp approach. However, the proposed algorithm localizes the rollback of a model within itself, not possible in the standard Time Warp approach. An advantage of such localization is that the simulation time may be reduced. To evaluate its performance, we simulate a single bus multiprocessor architecture system with an external common memory. Simulation result shows that significant speedup is made possible with our algorithm in a parallel environment.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.81-84
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• 2005

Various design schemes for network using wireless sensor nodes have been widely studied on the several application areas ranging from the real world information collection to environmental monitor. Currently, the schemes are focused on the design of sensor network for low power consumption, power-aware routing protocol, micro miniature operating system and sensor network middleware. The indoor localization system that identifies the location of the distributed nodes in a wireless sensor network requires features dealing with mobility, plurality and other environmental constraints of a sensor node. In this paper, we present an efficient location system to cope with mobility of multiple mobile nodes by designing a location handler that processes location information selectively depending on the nodes' density in a specific region. In order to resolve plurality of multiple mobile nodes, a routing method for the location system is also proposed to avoid the occurrence of overlapped location data.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1781-1786
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• 2005

In sensor network systems, all the nodes are interconnected and the positional information of each sensor is essential. To measure the temperature, position detection and communication functions are required. Many sensor nodes are distributed to a measurement field, and these sensors have three main functions: they measure the distance to the other nodes, the data of which are used to determine the position of each node; they communicate with other nodes; and they measure the temperature of each node. A novel range measurement method using the difference between light and sound propagation speed is proposed. The experimental results show the temperature distribution as measured with the aid of the determined positions. The positions of every node were calculated with a PC program. Eight nodes were manufactured and their fundamental functions were tested. The results of the range measurement method, which takes relatively accurate measurements, contribute significantly to the accuracy of the position determination. Future studies will focus on 3-D position determination and on the architecture of appropriate sensors and actuators.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.209-216
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• 2005

In wireless sensor networks, an estimation method is proposed for distances between nodes within two hops. The method uses only proximity information of nodes without physiccal distance measurements. It drastically improves the performance of localization algorithms based on Proximity information. In addition, it is the first method that estimates distances between nodes exactly in two hops. The distances are estimated from the number of common neighbors under an assumption that the number of common neighbors is proportional to the intersection of two unit disks centered at the two nodes. Simulation analysis shows that the estimation error is roughly from 10 to 20 percent of real distances. Meanwhile, the number of messages required by a distributed algorithm realizing this method is only two times the number of nodes.