• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1139-1144
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• 2015

The internet of things(: IoT) which could produce new information as well as service through connecting small devices with internet interface becomes reality and could be utilized in home, office and plant. Especially the IoT can provide our home for safety, security, convenience, and power saving since all devices form a small internet. This paper proposes an IoT prototype for home with Raspberry Pi which has various sensors and monitors environment. This Raspberry Pi sensor node is small and inexpensive but can provide powerful service. The implemented node goes beyond simple role of sensor node and features a kind of sensor web node which performs various functions to outer network. So the proposed IoT prototype can provide flexibility as well as extensibility since it does not need expensive server.

• Journal of Information Technology Services
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• v.10 no.4
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• pp.259-268
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• 2011

A robot education system by emulation based on Web can be efficiently used for understanding concept of robot assembly practice and control mechanism of robot by control programming. It is important to predict the path of the line tracer robot which has to be decided by the robot. Shortest Path Algorithm is a well known algorithm which searches the most efficient path between the start node and the end node. There are two related typical algorithms. Dijkstra Algorithm searches the shortest path tree from a node to the rest of the other nodes. $A^*$ Algorithm searches the shortest paths among all nodes. The delay time caused by turning the direction of navigation for the line tracer robot at the crossroads can give big differences to the travel time of the robot. So we need an efficient path determine algorithm which can solve this problem. Thus, It is necessary to analyze the overhead of changing direction of robot at multi-linked node to determine the next direction for efficient routings. In this paper, we reflect the real delay time of directional changing from the real robot. A speed based Dijkstra algorithm is proposed and compared with the previous ones to analyze the performance.

• Steel and Composite Structures
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• v.26 no.4
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• pp.463-471
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• 2018

The bolted end-plate beam-column connections have been widely used in steel structure and composite structure because of its excellent seismic performance. In this paper, the end-plate bolted connection is applied in the concrete structure, A new-type of fabricated beam-column connections with end-plates is presented, and steel plate hoop is used to replace stirrups in the node core area. To study the seismic behavior of the joint, seven specimens are tested by pseudo-static test. The experimental results show that the new type of assembly node has good ductility and energy dissipation capacity. Besides, under the restraint effect of the high-strength stirrup, the width of the web crack is effectively controlled. In addition, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

• Journal of the Korea Society of Computer and Information
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• v.22 no.9
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• pp.91-97
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• 2017

IoT (Internet of Things) systems are based on heterogeneous hardware systems of different types of devices interconnected each other, ranging from miniaturized and low-power wireless sensor node to cloud servers. These IoT systems composed of heterogeneous hardware utilize data sets collected from a particular set of sensors or control designated actuators when needed using open APIs created through abstraction of devices' resources associated to service applications. However, previously existing IoT services have been usually developed based on vertical platforms, whose sharing and exchange of data is limited within each industry domain, for example, healthcare. Such problem is called 'data silo', and considered one of crucial issues to be solved for the success of establishing IoT ecosystems. Also, IoT services may need to dynamically organize their services according to the change of status of connected devices due to their mobility and dynamic network connectivity. We propose a way of dynamically composing IoT services under the concept of WoT (Web of Things) where heterogeneous devices across different industries are fully integrated into the Web. Our approach allows developers to create IoT services or mash them up in an efficient way using Web objects registered into multiple standardized horizontal IoT platforms where their resources are discoverable and accessible. A Web-based service composition tool is developed to evaluate the practical feasibility of our approach under real-world service development.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.432-434
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• 2003

This paper developed the web based power flow program for education. Since a lot of users can connect and implement the web based program, the only one computer can get much evaluation burden not to compute. Using the XML technology, which supports the distributed computing technology, we have developed the web-based power flow software and system that are distributed the above calculation burden to three computers: web server, database server, application server. Also, this software was developed to get the difference of number of iteration and evaluation speed as veil as the results of state variables for each node according to the each calculation method for power flow using the chart. Therefore, users can get the physical concept of power flow in addition to the difference among the evaluation methods for power flow. We have performed the case studies with IEEE 14 bus system using the developed software.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.157-159
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• 2006

ZigBee technology that is observed to radio network of low electric power with latest WPAN's IEEE 802.15 .4 technologies is evaluated as best technology for sensor network and digital home network construction. This need exclusive use application for monitoring, managing, controlling and organizing this nodes. However, these program has weaknesses that is hard to construct flexible system with Internet. This paper will use web server linked with gateway to manage sensor network that is consisted of ZigBee node and design system that manages ZigBee device with relative fast responsibility using AJAX web technology.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.831-832
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• 2006

In this paper, we introduce a canonical framework of the large-scaled web-based sensor gateway and practically implement it as the environment monitoring system. The system consists of a central management server, up to 250 local embedded subsystems and up to 250 sensor or actuator nodes for each subsystem. The node information is gathered periodically through a well-defined protocol on the sensor network and converted to the web contents and the SNMP MIB objects according to its data type. The MIB objects are well-defined and include system, network, sensor, actuator and alarm specific data classes. Because there is an increasing trend that a large number of sites are willing to adapt unmanned sensing and control, the developed system will play a key role to efficiently manage a large scale sensor networked system such as environment monitoring systems or countermeasure systems against disaster and calamities.

• Journal of information and communication convergence engineering
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• v.1 no.2
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• pp.82-87
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• 2003

We are able to work on the shared virtual space in Web-based Collaborative Design System using only Internet and Web browser. Then the users will share 3D objects and must be able to pick the objects effectively which they want to manipulate. In this paper, picking is implemented not only by computing intersection of mouse pointer with the objects of the virtual world, but also by using capabilities and attributes of scene graph node, by setting bounds intersection testing instead of geometric intersection testing, by limiting the scope of the pick testing, using Java 3D. These methods can reduce the computation of picking and can pick 3D objects effectively and easily using the system of hierarchy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.1
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• pp.191-210
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• 2011

Topology management, which includes neighbor discovery, tracking and updating, is a key area that need to be dealt with appropriately to increase network performance. The use of directional antenna in Wireless Mesh Networks is beneficial in constructing backbone networks viewing the properties of directional antenna. The backbone links must be robust to obtain better network performance. In this paper, a simple yet effective topology protocol is presented that performs well compared to its predecessors. Our protocol constructs the topology with the constraints in the number of links per node. The full topology is constructed in two phases. The resultant topology is termed as Web-topology. The topology formed is robust, efficient, and scalable.

• Annual Conference of KIPS
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• 2020.05a
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• pp.2-4
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• 2020

논블로킹 IO 를 활용한 웹 서비스를 위한 미들웨어 구축 방법은 2009 년 발표된 Node.js 에서 도입된 이후로 여러 언어 및 프레임워크로 전파되기 시작하였다. 자바 진영에서도 Project Reactor 를 통하여 논블로킹 IO 패러다임에 대응하기 시작하였고 이를 스프링 프레임워크로 구현한 WebFlux 가 출시되었다. 본 논문은 자바 기반의 웹서비스 구축 시 스프링 프레임워크를 활용한 블로킹 기법과 논블로킹 기법 간의 차이점을 살펴보고 성능을 분석한다. 이를 통해 가장 효율적인 성능을 발휘할 수 있는 아키텍처 모델을 도출한다.