• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.849-851
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• 2003

A location-based service or LBS in a cellular telephone network is a service provided to the subscriber based on his current geographic location. This position can be known by user entry or a GPS receiver that he carries with him, but most often the term implies the use of a function built into the cell network that uses the known geographic coordinates of the base stations through which the communication takes place. One implication is that knowledge of the coordinates is owned and controlled by the network operator, and not by the end user. Location utility service provides two kinds of functions, geocoder and reverse geocoder. Geocoder converts an address into a coordinate and reverse geocoder changes a coordinate into an address. Because location utility service is the first step to progress LBS, various servises such as directory, routing, presentation, and etc require to access that. In this paper, we will describe the architecture of LBS platform and the concept and the role of location utility service.

• The Journal of Advanced Prosthodontics
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• v.9 no.6
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• pp.482-485
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• 2017

PURPOSE. This laboratory study aimed to investigate the effect of doping an acrylic denture base resin material with nanoparticles of ZnO, CaO, and $TiO_2$ on biofilm formation. MATERIALS AND METHODS. Standardized specimens of a commercially available cold-curing acrylic denture base resin material were doped with 0.1, 0.2, 0.4, or 0.8 wt% commercially available ZnO, CaO, and $TiO_2$ nanopowder. Energy dispersive X-ray spectroscopy (EDX) was used to identify the availability of the nanoparticles on the surface of the modified specimens. Surface roughness was determined by employing a profilometric approach; biofilm formation was simulated using a monospecies Candida albicans biofilm model and a multispecies biofilm model including C. albicans, Actinomyces naeslundii, and Streptococcus gordonii. Relative viable biomass was determined after 20 hours and 44 hours using a MTT-based approach. RESULTS. No statistically significant disparities were identified among the various materials regarding surface roughness and relative viable biomass. CONCLUSION. The results indicate that doping denture base resin materials with commercially available ZnO, CaO, or $TiO_2$ nanopowders do not inhibit biofilm formation on their surface. Further studies might address the impact of varying particle sizes as well as increasing the fraction of nanoparticles mixed into the acrylic resin matrix.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.1
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• pp.49-54
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• 2010

3GPP(Third Generation Partnership Project) LTE system that is the next step forward in cellular 3G services address the issues related to power saving at LTE base station. This is because that most of the energy in a typical telecommunication network is consumed by the wireless network's base station site. Power saving at LTE base station fall in with low-carbon green technology. This thesis proposes a power saving MAC protocol for LTE base station which utilizes different graded DRX/DTX(Discontinuous. Reception/Transmission). Considering traffic type in UE, proposed MAC protocol controls adaptive DRX/DTX cycle. The proposed method is more improve power saving performance than another method which is unchanged DRX/DTX by conditions. In this thesis, I propose an power saving MAC protocol in an environment where LTE base station are communicated with UE and prove improvement in performance through simulations.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.277-280
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• 2001

Due to the explosive popularization of the Internet, it has been researched for many mobile terminals how to receive various multimedia information. Especially, it has been considered that a mobile terminal is serviced with multimedia information through a inherent IP address. In this paper we have proposed the Handover Signaling Method and analyzed the Handover delay time of this proposed method in wireless section. This proposed method is appropriate to Broadband systems with Mobile IP. We have simulated Handover delay time with respect to the distance between a terminal and base stations

• Journal of the Korean School Mathematics Society
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• v.11 no.4
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• pp.595-608
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• 2008

The purpose of this study is to address the teachers' knowledge bases for effective mathematics teaching and especially to provide the various definitions and the structures of mathematics knowledge which is the most important one of the knowledge bases. The conceptual understanding about teachers' knowledge bases for effective mathematics teaching and the structure of mathematics knowledge may be used in evaluating effective mathematics teaching and teachers as well as in developing a new conceptual framework for the structure of mathematical knowledge.

• Proceedings of the CALSEC Conference
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• 1998.10b
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• pp.457-466
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• 1998

Internet-based EDI is emerging as a prominent substitute technology for traditional VAN-based EDI technology. The strength of this new technology is based on the explosive growth of Internet community, low "fixed-rate" Internet expense and "globally" open base of its participants. These strengths of Internet-baed EDI bring vast new opportunities for enterprises and thus. have as much implications for IT managers. However, Internet-based EDI technology has, at least by now, several drawbacks too. Most of these drawbacks also comes from the fact that it has its structural base on the Internet. Managers should carefully consider these drawbacks and hidden costs before adopting or switching to this attractive new technology. This presentation attempts to address major trends of Internet-based EDI and its implementation, opportunities and threats of the changes in technology, factors to consider in adopting this technology, and several managerial and strategic tradeoffs and implications of Internet-based EDI for IT managers.

• Electronics and Telecommunications Trends
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• v.32 no.5
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• pp.85-96
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• 2017

The research, design, and development of wireless access technologies using the new 6 to 100GHz band mmWave are actively underway in order to address the frequency shortage problem in the sub-6GHz band and accommodate the 5G technical requirements, such as the increased transmission capacity. Technical elements to efficiently overcome the problems caused by mmWave signal characteristics, support an effective interworking with a conventional communication service, and ensure smooth mobility between mmWave base stations and existing base stations are also being investigated. This paper discusses the technical solutions for an mmWave-based 5G RAN configuration and their considerations under various operational scenarios.

• Journal of Communications and Networks
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• v.15 no.4
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• pp.338-351
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• 2013

Multiple-input multiple-output (MIMO) communication may provide high spectral efficiency through the deployment of a very large number of antenna elements at the base stations. The gains from massive MIMO communication come from the use of multi-user MIMO on the uplink and downlink, but with a large excess of antennas at the base station compared to the number of served users. Initial work on massive MIMO did not fully address several practical issues associated with its deployment. This paper considers the impact of channel aging on the performance of massive MIMO systems. The effects of channel variation are characterized as a function of different system parameters assuming a simple model for the channel time variations at the transmitter. Channel prediction is proposed to overcome channel aging effects. The analytical results on aging show how capacity is lost due to time variation in the channel. Numerical results in a multicell network show that massive MIMO works even with some channel variation and that channel prediction could partially overcome channel aging effects.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5323-5343
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• 2018

Mobile applications and social networks tend to enhance the need for high-quality content access. To address the rapid growing demand for data services in mobile networks, it is necessary to develop efficient content caching and distribution techniques, aiming at significantly reduction of redundant content transmission and thus improve content delivery efficiency. In this article, we develop optimal cooperative content cache and distribution policy, where a geographical cluster model is designed for content retrieval across the collaborative small cell base stations (SBSs) and replacement of cache framework. Furthermore, we divide the SBS storage space into two equal parts: the first is local, the other is global content cache. We propose an algorithm to minimize the content caching delay, transmission cost and backhaul bottleneck at the edge of networks. Simulation results indicates that the proposed neighbor SBSs cooperative caching scheme brings a substantial improvement regarding content availability and cache storage capacity at the edge of networks in comparison with the current conventional cache placement approaches.

• Electronics and Telecommunications Trends
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• v.34 no.3
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• pp.86-92
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• 2019

New products and services, such as 5G and wireless power transmission equipment, have recently brought about changes in the field of electromagnetic technology. There is a need for the evaluation and measurement of the health effects of such technology. To address this need, the development of international standards related to human exposure to electromagnetic waves of these new technologies are currently being discussed. This article briefly introduces the International Standard Organization standards for human exposure to electromagnetic waves, and focuses on the major standard trends for SAR measurement techniques that employ vector probes, wireless power transfer, and 5G base station measurement.