• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1711-1717
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• 2014

There have been many studies on IEEE 802.15.4 for home area networks(HAN) in Smart Grids. Existing unslotted or slotted IEEE 802.15.4 has almost not met strict conditions of the U.S. Department Of Energy(DOE). This study proposed a improved algorithm that reduces collisions, delay time and changes in the delay time. For this purpose, numbers were given to nodes to make the transmission in the order of the node numbers. Since the probability of the occurrence of collisions would decrease compared to random transmission if the nodes were given numbers, Backoff time was set at 0. In the proposed Numbered-Unslotted-ZeroBackoff algorithm, when the packet size was 133 octets and less than 180 packets per second occurred, it was found that packet delivery ratio was over 99.99%, and that all the maximum delay, the mean delay and the minimum delay were less than 0.02 seconds. This paper could confirm that the algorithm proposed in this study met the strict conditions of the DOE.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.373-379
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• 2019

Smart-farm has been spreading across Korea to improve the labor efficiency and productivity of greenhouse crops. Although notable improvements have been made in the monitoring technologies and environmental-controlling systems in greenhouses, only a few simple decision-support systems are available for predicting the optimum environmental conditions for crop growth. In this study, a tomato growth model (GreenTom), which was developed by Seoul National University in 1997, was calibrated and validated to examine if the model can be used as a decision-supporting system. The original GreenTom model was not able to simulate artificial defoliation, which resulted in overestimation of the leaf area index in the late growth. Thus, an algorithm for simulating the artificial defoliation was developed and added to the original model. The node development, leaf growth, stem growth, fruit growth, and leaf area index were generally well simulated by the modified model indicating that the model could be used effectively in the decision-making of smart greenhouse.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.123-128
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• 2015

Recently, a communication protocol for connectivity between various sensors and actuators is issue the key technology in IoT(Internet of Things). IETF(Internet Engineering Task Force) CoAP(Constrained Application Protocol) protocol supports the communication between things like sensors and actuator nodes in a limited environment. Smart-phone will work for the data processing of the sensors and the management of IoT nodes at the next generation communication environment. In this paper, we design the connection for smart-phone and IoT node based using IETF CoAP protocol, and implement the middleware with the proposed data refinement on smart-phone. The middleware detects and eliminates a error data and duplicated data using the proposed data refinement. The proposed data refinement scheme supports to transfer a reliability information in the constrained environment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.119-126
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• 2017

Developing the TCP/IP standard IBA which is higher organization of IETF decided to attach the TCP/IP protocol stack to small things, such as sensor. This means small object is also considered as on of the communication node, it has symbolic meaning that expand smart object has all five layer. Under this background, IoT/WoT configure the intelligent network between objects based on the internet to communication was introduced. Things has own IP address on IoT environment and are smart object that a lot of people communicate over the internet on Application Layer. In other words, IoT is that smart object are commercialized space. According to the interest of IoT, IETF establish CoAP for use as IoT protocol. CoAP is expected that standard protocols created by things is connected to the Internet protocol that can be used within a constrained environment. Accordingly, in this paper, we proposed Middleware API that can manage and collect the data of objects that connected CoAP network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.45-53
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• 2012

In this paper, we proposed the efficient addressing scheme for improving the performance of routing algorithm by using ZigBee in Smart Grid environment. A distributed address allocation scheme used an existing algorithm that has wasted in address space. Therefore proposing x, y and z coordinate axes from divided address space of 16 bit to solve this problems. Each node was reduced not only bitwise but also multi hop using the coordinate axes while routing than $Cskip$ algorithm. I compared the performance between the standard and the proposed mechanism through the numerical analysis. Simulation verified performance about decrease averaging multi hop count that compare proposing algorithm and another. The numerical analysis results show that proposed algorithm reduced the multi hop better than ZigBee distributed address assignmen.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.613-621
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• 2019

In general, transfer in subway stations is defined as transfer between lines and station transfer. In transfer between lines, passengers change from one subway line to another by utilizing horizontal pedestrian facilities such as transfer passages and pedestrian way. Station transfer appears in the situation that subway lines of enter and exit gate terminals differs from those of boarding and alighting trains and passenger trips utilize both vertical pedestrian facilities such as stair and escalator and horizontal facilities. The hypothesis on these two transfers presupposes that all subway lines are operated by either local train or express in subway network. This means that in a transfer case both local and express trains are operated in the same subway line, as a case of Seoul Metro Line 9, has not been studied. This research proposes a methodology of finding the same line transfer in the Seoul metropolitan subway network built based on the smart card network data by suggesting expanded network concept and a model that passengers choose a theirs minimum time routes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.33-41
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• 2018

The idea of the Internet of Things as a platform on the Smart Campus has become increasingly popular. It requires an infrastructure consisting of communication networks, sensor nodes and gateways to connect to the Internet. Each sensor node is responsible for gathering data from the environment. This document outlines a network of wireless sensors on the Internet for the application of Smart Campus monitoring. Wireless sensor network Monitoring have become a complete solution to using a low power implementation and integrated systems. The numerous restrictions however result from the low communication range, the limited computing power, the lack of availability of the network protocol, the lack of programming security and the security failures in the areas of confidentiality, integrity and availability. A new security technique and its functionality for WSNM nodes developed. Development in the research of a secure network and suggestions for avoiding denial of service (DOS) and complexity attacks. These systems if properly implemented can provide an energy efficiency mechanism through pre-allocation and a new key from key management models with a secure routine algorithm.

• Journal of Korean Society of Rural Planning
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• v.25 no.2
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• pp.15-21
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• 2019

The agricultural environment is changing and becoming more advanced due to the influence of the 4th Industrial Revolution. From the basic plan of Rural Informatics to the current level of 2nd generation smart farms aimed at improving productivity using Big data, cloud network and more IoT technology. We are continuing to provide support and research and development. However, many problems remain to be solved in order to supply and settle smart farms in Korea. The purpose of this study is to provide a method of collecting and sharing data on farming environment and to help improve the income and productivity of farmers based on collected data. In the case of hog farm, the multiple sensors for environmental data like temperature, humidity and gases and the network environment for connecting the internet were established. The environment sensor was made using the ESP8266 Node MCU board as micro-controller, DHT22 sensor for temperature and humidity, and MQ series sensors for various gases in the hog pens. The network sensor was applied experimentally for one month and the environmental data of the hog farm was stored on a web database. This study is expected to raise the importance of collecting and managing the agricultural and environmental data, for the next generation farmers to understand the smart farm more easily and to try it by themselves.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.5
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• pp.338-344
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• 2014

As the role of information collection becomes increasingly important in the enormous data environment, there is growing demand for more intelligent information technologies for managing complex data. On the other hand, it is difficult to find a solution because of the data complexity and big scaled amount. Accordingly, there is a need for a special intelligent knowledge base frame that can be operated by itself flexibly. In this paper, by adopting switching function for signal transmission in the synapse of the human brain, I/E selective activation based knowledge reconfiguring mechanism is proposed for building more intelligent information management system. In particular, knowledge network design, a special knowledge node structure, Type definition, I/E gauge definition and I/E matching scheme are provided. Using these concepts, the proposed system makes the functions of activation by I/E Gauge, selection and reconfiguration. In a more efficient manner, the routing and reasoning process was performed based on the knowledge reconfiguration network. In the experiments, the process of selection by I/E matching, knowledge reconfiguration and routing & reasoning results are described.

• Electronics and Telecommunications Trends
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• v.29 no.5
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• pp.145-155
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• 2014

최근 급격히 증가하고 있는 모바일 데이터 트래픽으로 인하여 이를 효과적으로 수용할 수 있는 수동형 광 가입자망(PON: Passive Optical Network) 기술에 대한 요구사항도 높아져가고 있다. 특히, 서비스 제공 시간을 줄이고 망 신뢰성을 향상시키며 망 운용관리 비용을 줄이기 위하여 PON 인프라인 광 분배망(ODN: Optical Distribution Network) 링크에 대한 실시간 장애 검출 기술과 물리적 광 커넥션의 자동인식 및 통합관리 기술에 활발한 연구 및 표준화가 진행 중이다. 본고에서는 PON 링크의 실시간 장애 검출 기술 및 광 분배망 자동인식/통합관리 기술동향에 대하여 소개하고 연계된 국제 표준화 진행사항에 대해 알아본다. 마지막으로 ETRI에서 연구 개발 중인 스마트 RN(Remote Node) 기술에 대해 기술한다. 스마트 RN 기술은 장거리(60Km 이상), 고분기(128분기 이상) 추세로 진화되고 있는 PON망에 적용하여 자동화된 광계층의 장애 검출 및 ODN 인프라 자동인식/통합관리 기능을 제공한다.