• The KIPS Transactions:PartC
• /
• v.17C no.3
• /
• pp.271-280
• /
• 2010

For the next generation mobile communication system, diverse wireless network techniques such as beyond 3G LTE, WiMAX/WiBro, and next generation WLAN etc. are proceeding to the form integrated into the All-IP core network. According to this development, Beyond 3G integrated into heterogeneous wireless access technologies must support the vertical handover and network to be used of several radio networks. However, unified management of each network is demanded since it is individually serviced. Therefore, in order to solve this problem this study is introducing the theory of Common Radio Resource Management (CRRM) based on Generic Link Layer (GLL). This study designs the structure and functions to support the vertical handover and propose the vertical handover algorithm of which policy-based and MCDM are composed between LTE and WLAN systems using GLL. Finally, simulation results are presented to show the improved performance over the data throughput, handover success rate, the system service cost and handover attempt number.

• Journal of KIISE:Computer Systems and Theory
• /
• v.34 no.5_6
• /
• pp.176-186
• /
• 2007

An interconnection network can be represented as a graph where a vertex corresponds to a node and an edge corresponds to a link. The diameter of an interconnection network is the maximum length of the shortest paths between all pairs of vertices. The fault diameter of an interconnection network G is the maximum length of the shortest paths between all two fault-free vertices when there are $_k(G)-1$ or less faulty vertices, where $_k(G)$ is the connectivity of G. The fault diameter of an R-regular graph G with diameter of 3 or more and connectivity ${\tau}$ is at least diam(G)+1 where diam(G) is the diameter of G. We show that the fault diameter of a 2-dimensional $m{\times}n$ torus with $m,n{\geq}3$ is max(m,n) if m=3 or n=3; otherwise, the fault diameter is equal to its diameter plus 1. We also show that in $d({\geq}3)$-dimensional $k_1{\times}k_2{\times}{\cdots}{\times}k_d$ torus with each $k_i{\geq}3$, there are 2d mutually disjoint paths joining any two vertices such that the lengths of all these paths are at most diameter+1. The paths joining two vertices u and v are called to be mutually disjoint if the common vertices on these paths are u and v. Using these mutually disjoint paths, we show that the fault diameter of $d({\geq}3)$-dimensional $k_1{\times}k_2{\times}{\cdots}{\times}k_d$ totus with each $k_i{\geq}3$ is equal to its diameter plus 1.

• Journal of KIISE
• /
• v.43 no.11
• /
• pp.1233-1244
• /
• 2016

In the IoT network environments for LLNs(Low power and Lossy networks), IPv6 Routing Protocol for Low Power and Lossy networks(RPL) has been proposed by IETF(Internet Engineering Task Force). The goal of RPL is to create a directed acyclic graph, without loops. As recommended by the IETF standard, RPL route recovery mechanisms in the event of a failure of a node should avoid loop, loop detection, DIO Poisoning. In this process, route recovery time and control message might be increased in the sub-tree because of the repeated route search. In this paper, we suggested RPL route recovery method to solve the routing overhead problem in the sub-tree during a loss of a link in the RPL routing protocol based on IoT wireless networks. The proposed method improved local repair process by utilizing a route that could not be selected as the preferred existing parents. This reduced the traffic control packet, especially in the disconnected node's sub tree. It also resulted in a quick recovery. Our simulation results showed that the proposed RPL local repair reduced the recovery time and the traffic of control packets of RPL. According to our experiment results, the proposed method improved the recovery performance of RPL.

• The Journal of the Korea Contents Association
• /
• v.17 no.12
• /
• pp.1-10
• /
• 2017

Open data has received a lot of attention from around the world. The Korean government is also making efforts to open government data. However, despite the quantitative increase in public data, the lack of data is still pointed out. This paper proposes a method to improve data sharing and utilization by semantically linking public data. First, we propose a knowledge model for expressing administrative districts and their semantic relationships in Korea. An administrative district is an administrative unit that divides the territory of a nation, which is a unit of politics, according to the purpose of the state administration. The knowledge model of the administrative district defines the structure of the administrative district system and the relationship between administrative units based on the Local Autonomy Act. Second, a knowledge graph of the administrative districts is introduced. As a reference information to link public open data at a semantic level, some characteristics of a knowledge graph of administrative districts and methods for linking heterogeneous public open data and improving data quality are addressed. Finally, some use cases are addressed for interlinking between the knowledge graph of the administrative districts and public open data. In particular, national administrative organisations are interlinked with the knowledge graph, and it demonstrates how the knowledge graph can be utilised for improving data identification and data quality.

• Journal of Satellite, Information and Communications
• /
• v.2 no.2
• /
• pp.41-47
• /
• 2007

The first geostationary satellite made by Korea, COMS, has the three different payload ; Meteorological sensor, Oceanographic sensor and Ka-band communication payload. There are Meteorological & Ocean Data Communication Subsystem(MODCS) and Telemetry, Command and Ranging Subsystem(TC&R) as other RF radiation sources. MODCS transmits and receives Meteo and Ocean measurement data from/to earth using L-band and TC&R using S-band. The Ka-band communication payload will provide high-speed multimedia services and communication services for natural disaster such as prediction, prevention, and recovery services in the government communications network.Ka-band beacon is for the earth antenna pointing and the experiment of rain fading. This paper gives the analysis results about the mutual radiation effect on Ka-band communication payload, Ka-band beacon, MODCS and TC&R. Up/Down link power and coupling factor including the geometrical position and distance of antenna, filter rejection and degradation factor due to the different polarization are considered. The results show MODCS and TC&R are compatible for Ka-band communication payload and Ka-band beacon does not interfere with MODCS and TC&R normal operation.

• The KIPS Transactions:PartD
• /
• v.12D no.2 s.98
• /
• pp.309-318
• /
• 2005

In order to present wireless Internet users with previously created HTML contents and applications, it is essential to research and develop the technology to efficiently convert HTML documents into documents and further provide a way to edit the WML documents. This paper describes the design and development of a WML converter and WML editor The WML converter can convert HTML pages in real time into WML documents that are suitable for the WAP environment. The WML editor enables creation and modification of WML documents in a WYSIWYG fashion. These tools enable the previous services based on HTML documents to be easily adapted to the wireless environment. The developed WML converter can be installed on a proxy server to support real time conversion of Web contents. It is superior to other converters in terms of the various image formats it supports and the improvements on the conversion of the link and frame tags. Users can continuously browse via links and also view frames. Automatic dividing of large WML documents into WML cards md user defined conversion rules are also supported. The WML editor is also integrated with the converter and provides an integrated WYSIWYG environment for creating, converting and publishing WML documents.

• The KIPS Transactions:PartC
• /
• v.13C no.2 s.105
• /
• pp.219-226
• /
• 2006

The shortest path is only maintained during short time because network topology changes very frequently and each mobile nodes communicate each other by depending on battery in MANET(Mobile Ad-hoc Network). So many researches that are to overcome a limitation or consider a power have executed actively by many researcher. But these protocols are considered only one side of link stability or power consumption so we can make high of stability but power consumption isn't efficient. And also we can reduce power consumption of network but the protocol can't make power consumption of balancing. For that reason we suggest RBSSPR(Residual Battery Capacity and Signal Strength Based Power-aware Routing Protocol in MANET). The RBSSPR considers residual capacity of battery and signal strength so it keeps not only a load balancing but also minimizing of power consumption. The RBSSPR is based on AODV(Ad-hoc On-demand Distance Vector Routing). We use ns-2 for simulation. This simulation result shows that RBSSPR can extense lifetime of network through distribution of traffic that is centralized into special node and reducing of power consumption.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.4
• /
• pp.421-426
• /
• 2010

Due to the ease of deployment and the extended coverage, wireless mesh networks (WMNs) are gaining popularity and research focus. For example, the routing protocols that enhance the throughput on the WMNs and the link quality measurement schemes are among the popular research topics. However, most of these works assume that the locations of the mesh routers are predetermined. Since the operators in an Indoor mesh network can determine the locations of the mesh routers by themselves, it is essential to the WMN performance for the mesh routers to be initially placed by considering the performance issues. In this paper, we propose a mesh router placement scheme based on genetic algorithms by considering the characteristics of WMNs such as interference and topology. There have been many related works that solve similar problems such as base station placement in cellular networks and gateway node selection in WMNs. However, none of them actually considers the interference to the mesh clients from non-associated mesh routers in determining the locations of the mesh routers. By simulations, we show that the proposed scheme improves the performance by 30-40% compared to the random selection scheme.

• Journal of Korean Society of Archives and Records Management
• /
• v.6 no.2
• /
• pp.57-85
• /
• 2006

There should be an integration between work management and records management in order to document the work processes thoroughly. It's proper to establish a records classification system to have the work classification and record classification table integrated for that purpose. But the conventional procedures and methodology used for records classification system development lack specific features to be used as voluntary guidelines of a common organization or group and to conduct analysis. Recognizing the problems, this study suggested the specific methods of records classification system development to link work management and records management organically. First, the functional classification was chosen as the principle of classification for records classification system development. Then concrete methods of records classification system development were suggested. Analysis and comparison were made for the DIRKS(Designing and Implementing Recordkeeping Systems), which is the standard records management and work analysis of Australia, and AS 5090. The results were used to suggest specific methods of records classification system development in conjunction with the research into the methodology employed for work analysis in information engineering and business administration to compensate for its weakness. The significance of the study can be found in that it suggested the methods of typical records classification system development in connection with records classification, and that it applied them to the Presidential Committee for the Inspection of Collaborations for Japanese Imperialism and tested them.

• The Journal of Korean Society for School & Community Health Education
• /
• v.2 no.2
• /
• pp.89-99
• /
• 2001

This paper is based on the assumption that the sexual awareness and sexual behaviour of high school students would show the difference between an academic high school and a vocational high school. The main purpose of this paper is to provide basic information on establishing the direction of a realistic and efficient education, which leads to the desirable sex ethics eventually. To do this, a comparative study was carried out to figure out the difference between academic high school students and vocational high school students in terms of their actual awareness and behaviour of sex. I put the following two questions in order to achieve the goal of this study. First, what is the difference in sexual awareness between academic high school students and vocational high school students? Second, what is the difference in sexual behaviour between academic high school students and vocational high school students? The subjects of the survey conducted were 595 high school students in Kyunggi Province and I made the questionnaires referencing pre-studies. The SPSS program was used to get a frequency and a percentage from the results of the survey and then, by applying t-text, $x^2$ verification and interrelation, the following results were obtained. First, regarding sexual awareness, there wasn't much difference in their idea of keeping virginity before marriage between academic high school students and vocational high school students. From the results obtained by analyzing the interrelation between students and their parents and friends in terms of a will to keep virginity, it is found that there was a relevance in both academic high school and vocational high school. When they have a sex problem, it was friends that they are looking for consulting and both groups showed thesame result. But pertaining to an experience of a sex education, the comparative analysis indicated an meaningful difference. Second, as for sex behaviour, it was shown that there was a difference in the experience of going out with the other sex between academic high school students and vocational high school students as well as in the degree of physical touch. However, not much difference was shown in controlling a sex desire between the two groups. As a results of the comparative analysis of the sex experience between the two groups, there was a meaningful difference. In terms of the object of their sex experience, the majority of students in the two groups chose a friend as their first answer and there was little difference. From these results I can draw some conclusions that most of the students in both groups have a link with friends and parents in keeping their virginity. Furthermore, a meaningful difference in experiencing a sex education is presented between the two groups. With regard to the sex behaviour of high school students, a meaningful difference is shown in dating the other sex, a physical touch and a sex experience between the two groups. Consequently, we realize that there is a meaningful difference in some variants on the sexual awareness and sexual behaviour of high school students between academic high school and vocational high school.