• Korean Journal of Agricultural Science
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• v.38 no.4
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• pp.747-752
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• 2011

Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, $CO_2$, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.1
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• pp.15-20
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• 2016

Recently, the u-IT applications for plants and livestock become larger and control of livestock farm environment has been used important in the field of industry. We implemented wireless sensor networks and farm environment automatic control system for applying to the breeding barn environment by calculating the THI index. First, we gathered environmental information like livestock object temperature, heart rate and momentum. And we also collected the farm environment data including temperature, humidity and illuminance for calculating the THI index. Then we provide accurate control action roof open and electric fan in of intelligent farm to keep the best state automatically by using collected data. We believed this technology can improve industrial competitiveness through the u-IT based smart integrated management system introduction for industry aversion and dairy industries labor shortages due to hard work and old ageing.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.302-307
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• 2004

It need remote storage system using iSCSI to overcome a limit of PDA storage device used in currently wireless network environment, and IPSec to solve a security problem of wireless environment increasing continually. In this paper, it design and implement iSCSI to use a remote storage system on PDA, and IPSec for security. The experimental results in real environment show a system performance.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.161-171
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• 2019

Government transactions over wireless electronic devices are not safe and hence the messages are prone to attack. Thereby, devices supporting wireless Internet must assure the same level of security and privacy as the wired network. National public key infrastructure (NPKI) for electronic government used in the wired environment is not suitable for wireless environment for mobile government (mGovernment) because of the limitations of computing power, memory capacity and restricted battery power. This requires the development of a new NPKI for mGovernment, denoted as mNPKI, to developing countries, which provides the same security level as the wired NPKI. For the wireless environment requirements, mNPKI is based on short lived certificates. Analysis shows that mNPKI is well suited to wireless Internet and provides the same security requirement from the wired NPKI.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.50-54
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• 2014

Evaluation of the possible or probable effects of environmental conditions which are temperature, radiation, dust as well as other possibilities in terms of meteoroids, seismicity, and no global magnetic field has been carried out for wireless communications on the lunar surface in this paper. The results considered in this paper can be utilized as a basic information on making efficient use of the design for wireless communications system in Korean lunar exploration project.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.1 s.6
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• pp.107-115
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• 2005

For effective IP based service implementation on the wireless network environments, wireless network including the ITS network have to support QoS guaranteed protocol such as a RSVP. RSVP is a resource reservation protocol for Internet environment, and its scalability makes easy to implement RSVP over the various IP transport technologies. But for the If based ITS wireless network environment, RSVP is not suitable, since by its path setup procedure characteristic. In the wireless access network for ITS service, when a mobile node moves to other domain it must perform registration procedure. But the registration procedure is time consuming steps, so if a RSVP session was already established in the previous domain, the RSYP session may be disconnected and the time to re establish a new RSVP session is long enough to cause serious packet loss. In this paper, we propose a pre-path reservation mechanism for applying the RSVP in wireless access networks for ITS. In the pre-path reservation mechanism, the resource reservation procedure occurred during a mobile node's handoff time. An access point in wireless access network performs this procedure when the mobile node attempts handoff The access point executes pre-path reservation procedure as a proxy, since the mobile node does not have IP address until the address allocation procedure is finished in a new domain.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.1004-1012
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• 2009

Although it is raising expectation of multimedia multicast services in various wireless networks, it requires an efficient IP multicast group membership management in wireless environment. However, the existing IGMPv3/MLDv2 protocols are too heavy; they are not suitable for wireless environment. Moreover they suffer from a number of problems, such as unreliable signaling, slow state transition, low spectral efficiency, bulk report, and interrupting dormant receivers. In this paper, we propose a wireless host agent (WHA)-based IP multicast group management scheme that requires a reduced number of signaling, which also solves such problems effectively. We develop an analytic model to quantify costs of bandwidth usage and signaling overhead, and perform comparison and analysis of the proposed scheme.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.1
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• pp.9-23
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• 2013

In recent days, there are many researches of wireless LAN services as the communication environment of wireless LAN are so improved that a lot of services are available in wireless environments. The frequency of the wireless LAN is a general resource that can be used to everyone without any permission. Many technologies using this ISM (Industry Science Medical) frequency band are developed fast and widely. But, as many devices use the same frequency band at th same time, the service quality is degraded and the speed of the service rate id degraded by the result of the interference. For overcome this problem, we must provide the new technology of the mobile devices and a new cell design scheme for obtaining maximum throughput that considering the wireless environments effectively. In this paper, we explain the main technology at the IEEE 802.11n environments and proposes the optimal cell design and reference model for gaining maximum performance to many mobile devices at the same time by investigating real environment testing results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.2
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• pp.354-359
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• 2016

Power plants maintenance data is to be sent to management server system via a communication network. In this case, reliable communication network is required. Transmission of the power plants maintenance data is used in the wired communication network or wireless communication network. PLC communication network is a kind of wired communication network. However PLC communication network is easily affected by noise. On the vulnerable areas in power line system, such as a mountain or rural areas, it is difficult to form a power line communication network. For a wireless communication, environment are also influenced factors in wireless communication. Harsh environmental factors are bring the communication characteristic degradation. In such areas it can be used a combination of two networks and in this way the complementary function can be achieved. Power plants are distributed in various regions across the country. The appropriate communication network is needed to maintain the power plant.This study investigated the effect of environment on the wired communication and wireless communication. It would examine a variable factor which is affect to the communication characteristic. We used PLC communication for wired communication network and ZigBee communication for wireless communication network. We investigated the characteristics of a single communication network and it raised the need for a complex communication technology to complement a single communication network.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.141-147
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• 2004

Recently, Mobile phone became a great member of people. It is increased an use of mobile phone a population. According to mobile phone service. Also a carrying along like CDMA terminal became a small size. a light weight. A phone increased in an environment mobile phone service. For the reason it is demand as necessary evaluation iterms development and test environment construct. In this thesis. mobile phone service an environment is necessary an test principal and interest. wireless network is used Wireless Data. To recommand a Wireless Data quality evaluation method and to look upon next generation.