• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.4
• /
• pp.572-584
• /
• 1993

In this paper, we propose an efficient method to allocate carrier frequencies so as to minimize intermodulation products in two-level SCPC systems in which Hub station and many Remote stations communicate each other through the satellite transponder. Also we present a very efficient method to evaluate intermodulation products with highly reduced CPU time in two-level SCPC systems. We study and analyze the performance of some possible methods to extend the Deletion and Insertion operation, which is proposed by Okinaka and applied to only one-level SCPC systems, to two-level SCPC systems. The proposed algorithm is carefully selected out of these methods and is optimized, which shows superior performance to any other published strategies, especially in that it has very excellent characteristics in terms of generality for practical application. Considering the fact that most published strategies are seldom applicable to actual two-level SCPC systems, we can say that the proposed algorithm in this paper is quite meaningful.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.6B
• /
• pp.583-591
• /
• 2011

We presents the architecture of the 2.5 Gbps hybrid PON link which can increase of the transmission distance and link capability, and split ratio by using a colorless DWDM-PON and O/E/O based reach extender into an existing G-PON link. A RSOA based DWDM-PON to apply the feeder fiber can provide a link capacity of 32 larger that of a legacy G-PON. The reach extender converts the wavelength of DWDM-PON to G-PON through GTC frame regeneration at the remote node, and can provide a burst reset signal in order to extract upstream burst signal, simultaneously. The proposed hybrid PON enable a legacy G-PON to operate over the maximum 60 km distance with a 128-way split per WDM wavelength.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.10
• /
• pp.1256-1262
• /
• 2016

As the population of camping is increased in campsites and auto camp sites, the electrical equipment can safely supply electricity to users in a variety of electricity bill policy is required in the campsite. In this paper, we develop the vending machine for electricity that can control the outdoor electrical outlet from the management server using the Z-Wave WPAN and android mobile application. The developed vending machine for electricity consists of the management server, the controller, the outdoor outlet box, and the mobile application. The management server provides reservation and electricity bill payment to users. The management server controls the electrical outlet box through the controller to safely supply electricity to users. The controller that is a relay device between the management server and the switch controls switches based on Z-Wave mesh network. Outdoor electrical outlet box has 2 meter switches. We receive the relevant authorization to provide commercial electricity services using the outdoor electrical outlet box in the campsite.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.11
• /
• pp.2113-2119
• /
• 2006

In this paper, we design the r-Sensor protocol for reliable data transmission in the Intelligent Home Service based on the wireless sensor network environment. The r-Sensor protocol improve the reliability of data transmission and node fairness using simple routing algorithm, congestion control, and loss recovery method that minimize the load of relay node. Reposed routing algorithm find out upstream and downstream nodes using the Network Management packet. Meanwhile, loss recovery algorithm uses the Aggregated-Nack. To apply supposed algorithm, the IHS-AMR(Intelligent Home Service - Automatic Meter Reader) and sensor node are designed and implemented in hardware. The IHS-AMR provides remote metering service and also offers home safety service by internetworking with sensor network, mobile phone network and internet.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2004.05b
• /
• pp.748-751
• /
• 2004

In this paper, we discuss about wireless Internet security. The past few years have seen unprecedented growth in the number of wireless user, applications, and network access technologies. Wireless Internet is similar to wired internet, but it has some constrained wireless environment. So many internet technologies for wireless are developing now. There are WAP(Wireless Application Protocol) and WPKI. WAP(now version 2.0) is a protocol specification for wireless communication networks. it provides an application framework and network protocols for wireless devices such as mobile telephones, PDAs and internet technologies. In this paper some analysis of security(e.g. digital signature or encryption) for wireless internet are performed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.11
• /
• pp.2187-2192
• /
• 2016

A data-centric routing protocol considering a data aggregation technique at relay nodes is required to increase the lifetime of wireless sensor networks. An energy-efficient data-centric routing algorithm is proposed by considering a tradeoff between acquisition time and energy consumption in the wireless sensor network. First, the proposed routing scheme decides the sink node among all sensor nodes in order to minimize the maximum distance between them. Then, the proposed routing extends its tree structure in a way to minimize the link cost between the connected nodes for reducing energy consumption while minimizing the maximum distance between sensor nodes and a sink node for rapid information gathering. Simulation results show that the proposed data-centric routing algorithm has short information acquisition time and low energy consumption; thus, it achieves high energy efficiency in the wireless sensor network compared to conventional routing algorithms.

• The KIPS Transactions:PartC
• /
• v.19C no.1
• /
• pp.9-18
• /
• 2012

In 2010, Pedro et al. proposed RFID distance bounding protocol based on WSBC cryptographic puzzle. This paper points out that Pedro et al.'s protocol not only is vulnerable to tag privacy invasion attack and location tracking attack because an attacker can easily obtain the secret key(ID) of a legal tag from the intercepted messages between the reader and the tag, but also requires heavy computation by performing symmetric key operations of the resource limited passive tag and many communication rounds between the reader and the tag. Moreover, to resolve the security weakness and the computation/communication efficiency problems, this paper also present a new RFID distance bounding protocol based on WSBC cryptographic puzzle that can provide strong security and high efficiency. As a result, the proposed protocol not only provides computational and communicational efficiency because it requires secure one-way hash function for the passive tag and it reduces communication rounds, but also provides strong security because both tag and reader use secure one-way hash function to protect their exchanging messages.

• Journal of Aerospace System Engineering
• /
• v.12 no.1
• /
• pp.35-41
• /
• 2018

Unmanned Aerial Vehicles (UAV) have been used for various purposes in multiple fields, such as observation, communication relaying, and information acquisition. Nowadays, UAVs must have high performance in order to acquire more precise information in larger amounts than is now possible while performing for long periods. At present, domestically, a high-altitude long-endurance UAV (HALE UAV) for long-term flight in the stratosphere has been developed in order to replace some functions of the satellite. In this study, as a part of structural soundness evaluation of the aircraft structure developed for the HALE UAV, the structural soundness of the fasteners of the fuselage and tail is evaluated by calculating the margin of safety(M.S). The result confirms the validity of the design of the fasteners in the aircraft structure of the UAV.

• Journal of Broadcast Engineering
• /
• v.24 no.4
• /
• pp.553-563
• /
• 2019

As the number of videos uploaded on live streaming platforms rapidly increases, the demand for providing highlight videos is increasing to promote viewer experiences. In this paper, we present novel methods for predicting highlights using chat logs and audio data in videos. The proposed models employ bi-directional LSTMs to understand the contextual flow of a video. We also propose to use the features over various time-intervals to understand the mid-to-long term flows. The proposed Our methods are demonstrated on e-Sports and baseball videos collected from personal broadcasting platforms such as Twitch and Kakao TV. The results show that the information from multiple time-intervals is useful in predicting video highlights.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.05a
• /
• pp.404-407
• /
• 2014

Delay Tolerant Network (DTN) is a networking architecture that is designed to solve network problem in unstable and stressed environments using the Store-Carry-Forward method. Different form general networks, DTN does not guarantee the end-to-end connectivity, it is hard for the exiting TCP/IP based protocols to normally work due to the characteristic such as large latency and unstable link connectivity. And the condition that send massage without the information of the destination occurs frequently. Thus, suitable routing protocols for DTN are required and being researched. In this paper, we propose a novel routing protocol for DTN utilizing epidemic and prediction based algorithm to prevent the defect of previously DTN routing protocols such as the absence of the holistic view of the network. Proposed algorithm predicted destination using the mobility information recorded in neighbor node's history and utilize epidemic based algorithm when occurred condition without destination's information. This algorithm is enhanced in terms of delivery ratio, decreases latency and overhead in sparse network such as DTN.