• Spatial Information Research
• /
• v.19 no.4
• /
• pp.45-54
• /
• 2011

In this paper, we propose a hybrid index structure, called the SQMR-tree(Spatial Quad MR-tree) that can process spatial data efficiently by combining advantages of the MR-tree and the SQR-tree. The MR-tree is an extended R-tree using a mapping tree to access directly to leaf nodes of the R-tree and the SQR-tree is a combination of the SQ-tree(Spatial Quad-tree) which is an extended Quad-tree to process spatial objects with non-zero area and the R-tree which actually stores spatial objects and are associated with each leaf node of the SQ-tree. The SQMR-tree consists of the SQR-tree as the base structure and the mapping trees associated with each R-tree of the SQR-tree. Therefore, because spatial objects are distributedly inserted into several R-trees and only R-trees intersected with the query area are accessed to process spatial queries like the SQR-tree, the query processing cost of the SQMR-tree can be reduced. Moreover, the search performance of the SQMR-tree is improved by using the mapping trees to access directly to leaf nodes of the R-tree without tree traversal like the MR-tree. Finally, we proved superiority of the SQMR-tree through experiments.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.5
• /
• pp.10-22
• /
• 2015

Recently, 3rd Generation Partnership Project (3GPP) has developed sidehaul system to cope with the explosively increasing mobile data traffic. The sidehaul system is based on single carrier-frequency division multiple access (SC-FMDA) due to its low peak to average power ratio (PAPR). Also, antenna array is designed to support multiple input multiple output (MIMO) in a restricted space. In this paper, we design the antenna array about uniform linear array (ULA), uniform circular array (UCA) and uniform planar array (UPA), and analysis the performance in sidehaul system. In addition, we propose the novel hybrid receiver full suppression cancellation (FSC) to reduce the interference from neighbor cell in sidehaul system. The proposed receiver can suppress and cancel the interference by combining interference rejection combining (IRC) with successive interference cancellation (SIC).

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.6
• /
• pp.78-85
• /
• 2009

In time-varying multipath fading channels, orthogonal frequency division multiple access (OFDMA) uplink systems suffer severe performance degradation caused by inter-channel interference (ICI). In this paper, we propose a hybrid interference cancellation (HIC) for suppressing the degradation effect of ICI. The proposed HIC can achieve both exact interference cancellation and low detection complexity through efficient combination of parallel detection and serial cancellation. Simulation results show that, as the effect of Doppler increases, the proposed HIC achieves bit error rate (BER) performance enhancement in compared with severe performance degradation of conventional OFDMA receivers. In addition, both the computational complexity and total detection time are reduced.

• The Journal of Korean Association of Computer Education
• /
• v.3 no.2
• /
• pp.67-75
• /
• 2000

Due to the advantages of Internet, many teachers use Internet as an educational tool and due to the computerized works in schools, the usages of the Internet increase. However, because of the openness of the Internet, the sensitive data of an organization are exposed to outsiders and the Internet-based working has some problems such as the corruptions of instructional data or on-line assessment results. The need for protecting a school network from outsiders increases but the school networks with firewalls rarely exist. In this paper, in order to solve the security problem of a school network, we construct a hybrid firewall for school networks. In addition, we implement a graphical user interface for teachers to set up the access control rules of a hybrid firewall easily. The interface also provides the facilities such as log analysis, a real-time monitor for network traffics, and the statistic on traffics.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.5A
• /
• pp.527-536
• /
• 2004

A novel hybrid multiple access system, TD-BCDMA, where Binary CDMA that maintains a constant amplitude by clipping the summation of input signals multiplied by the orthogonal codes is transmitted over a TDMA frame structure, was Nosed. In every time slot of TDMA, binary CDMA modulated multiple channel signals are transmitted with the same waveform of TDMA. TD-BCDMA has all the advantages of TDMA. Flexible adjustment of the data transmission rate In demand is possible by adjusting the number of codes and time slots assigned to each user. This property was used to show an example of Ad Hoc network applications. To obtain a proper synchronization scheme for TD-BCDMA, the Receiver Operating Characteristics performance and the false alarm probability and false dismissal probability under various channel environment of two different schemes, a preamble scheme as in TDMA and a synchronization channel scheme as in CDMA were compared. It was proved that the preamble scheme is more practical and suitable than the synchronization channel scheme for the hybrid multiple access system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.10A
• /
• pp.1462-1470
• /
• 1999

In this paper, the performance of packet radio networks using the ALOHA protocol in Rayleigh fading channels is analyzed in terms of the capture probability and the throughput. We consider capture effect in order to increase the probability of the channel access and to include cellular environment we assume that the traffic is a truncated bell-shaped distribution. The packet proposed in this paper consists of a competition part and a data part to decrease the probability of collision in the channel access. In the competition part, DS system with common spreading code is used and in the data, hybrid DS/FH system is used. We consider the linear correlation receiver and the hard-limiting correlation receiver as the receiver model. BPSK modulation is also employed. Because hybrid DS/FH systems are not sensitive to variation of the interference power, as we choose a proper chip number N and a frequency hopping number q, we can obtain a steady system performance even though the variation of interference power is severe fading channels such as Rayleigh fading.

• The KIPS Transactions:PartC
• /
• v.10C no.5
• /
• pp.611-616
• /
• 2003

Recently, the HFC-CATV network stand in a substructure of superhighway information network. Because of sharing up to 500 of subscribes, the Collision Resolution Algorithm needs in the upstream channel of HFC-CATV network. In order to provide Quality of Service (QoS) to users with real-time data such as voice, video and interactive service, the research of Collision Resolution Algorithm must include an effective priority scheme. In IEEE 802.14, the Collision Resolution Algorithm has high request delay because of static PNA(Priority New Access) slots structure and different priority traffics with the same probability. In order to resolve this problem, this paper proposed dynamic priority collision resolution algorithm with ternary tree algorithm. It has low request delay according to an increase of traffic load because high priority traffic first resolve and new traffic content with different probability. In the result of the simulation, it demonstrated that the proposed algorithm needs lower request delay than that of ternary tree algorithm with static PNA slots structure.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.8
• /
• pp.681-687
• /
• 2014

Internet traffic is rapidly increasing due to the spread of personal smart devices. It causes serious burden on base stations and access points which are installed in buildings, buses, trains, and ships. We consider a communication scenario aboard a cruise ship and propose efficient contents distribution schemes to alleviate the burden of access points with multi-device-to-multi-device(MD2MD) communication. The proposed transmission method is based on the hybrid STBC-SM scheme. We compare the error performance of MD2MD communication system on the cruise ship using space-time block coding (STBC) scheme, spatial multiplexing (SM) scheme. The proposed MD2MD communication system is expected to adopt in the ship-area-network (SAN) with efficient contents distribution and reliable communication.

• Korean Institute of Interior Design Journal
• /
• v.24 no.3
• /
• pp.146-155
• /
• 2015

It is an undeniable fact that the modern people's interest in knowledge and information and their roles are some of the core factors used to define the modern society. Besides, as phenomena indicating and leading the modern society, we have fusion, hybrid and convergence, etc. that combine several different elements into a new one. Such changes in social, cultural and technological circumstances require a paradigm shift for the composition of knowledge and information facilities and space. However, more diversified and advanced recently, interfaces for the delivery of knowledge and information cause users to show new behaviors and even change the spatial concept with space composition elements hybridized. Especially for the space of libraries, it is necessary to access and utilize any forms of knowledge and information data (digital + analog) regardless of time and space limitations and approach with an integrated spatial concept likely to change flexibly depending on social demands. In this light, this study aims to make a basic proposal for sustainable integrated-type hybrid space for the space of a public library in this era of knowledge and information. Particularly, this study intends to seek a way to establish a hybrid space model that can effectively converge the most important factors of the space of libraries (human-space(network)-information). With 18 different cases, this study analyzed knowledge and information composition systems, knowledge and information delivery systems and users' space systems. As a result, this study extracted 3 kinds of models, an information-based model, a culture-based model and an education-based model, with the integrated hybrid space model of knowledge and information facilities

• Journal of Korean Library and Information Science Society
• /
• v.47 no.4
• /
• pp.265-288
• /
• 2016

The study aimed to suggest a model sample for guidance system for copyright of domestic journals and open access policy. Toward this end, analyses were conducted to examine copyright of domestic journals and open access environment. As a result of analyses, it turned out that 33.8% of domestic journals had 'regulations on ownership of rights to papers published in journals,' and that the subject to ownership of rights to papers published in domestic journals accounted for 28.8%, which was the highest rate. Of domestic journals, 34% charged a subscription fee, and they were toll access journals, and 56% were free access journals. As for system examples of guide system for copyright of foreign journals and open access policy, analyses were conducted to examine and investigate SHERPA/RoMEO in the U.K. and SCPJ in Japan and generate considerations at a time of domestic application. What needs to be taken into account is that overseas examples are focused on collecting and introducing self-archiving policy by authors for academic journals, so there are limitations in offering information including open access publication policy for domestic journals. Based on the analytical result, the study designated the purpose, direction and four steps that need to be considered at a time of development of guide system models for copyright and open access policy for domestic journals before suggestion of the basic direction and operational methods by stage.