• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.12C
• /
• pp.1181-1185
• /
• 2005

A combining of MIMO signal processing with OFDM is regarded as a promising solution of enhancing the performance of next generation wireless system. Therefore, in this paper, an OFDM-based wireless system employing layered space-time architecture is considered for a high-rate transmission. In the MIMO-OFDM system, we evaluate the PAR performance using the SLM approaches. The investigated SLM scheme for MIMO-OFDM signals selects the transmitted sequence with lowest average PAR over all transmitting antennas and retrieves the side information very accurately at the expense of a slight degradation of the PAR performance. The low probability of false side information can improve the overall detection performance of the MIMO-OFDM system with erroneous side information compared to the ordinary SLM approache, respectively. Also, we provide closed form of the average BER performance in MIMO-OFDM system using analytic approach.

• The Journal of Korean Institute of Next Generation Computing
• /
• v.13 no.4
• /
• pp.29-39
• /
• 2017

Various electronic warfare situations drive the need to develop an integrated electronic warfare simulator that can perform electronic warfare modeling and simulation on radar threats. In this paper, we analyze the components of a simulation system to reversely model the radar threats that emit electromagnetic signals based on the parameters of the electronic information, and propose a method to gradually maintain the reverse extrapolation model of RF threats. In the experiment, we will evaluate the effectiveness of the incremental model update and also assess the integration method of reverse extrapolation models. The individual model of RF threats are constructed by using decision tree, naive Bayesian classifier, artificial neural network, and clustering algorithms through Euclidean distance and cosine similarity measurement, respectively. Experimental results show that the accuracy of reverse extrapolation models improves, while the size of the threat sample increases. In addition, we use voting, weighted voting, and the Dempster-Shafer algorithm to integrate the results of the five different models of RF threats. As a result, the final decision of reverse extrapolation through the Dempster-Shafer algorithm shows the best performance in its accuracy.

• KIPS Transactions on Software and Data Engineering
• /
• v.11 no.11
• /
• pp.447-454
• /
• 2022

In the era of the 4th industrial revolution, we are living in a flood of information. It is very difficult and complicated to find the information people need in such an environment. Therefore, in the flood of information, a recommendation system is essential. Among these recommendation systems, many studies have been conducted on each recommendation system for movies, music, food, and clothes. To date, most personalized recommendation systems have recommended clothes, books, or movies by checking individual tendencies such as age, genre, region, and gender. Future generations will want to be recommended clothes, books, and movies at once by checking age, genre, region, and gender. In this paper, we propose a recommendation system that recommends personalized clothes and food at once according to the user's emotions and weather. We obtained user data from Twitter of social media and analyzed this data as user's basic emotion according to Paul Eckman's theory. The basic emotions obtained in this way were converted into colors by applying Hayashi's Quantification Method III, and these colors were expressed as recommended clothes colors. Also, the type of clothing is recommended using the weather information of the visualcrossing.com API. In addition, various foods are recommended according to the contents of comfort food according to emotions.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.13 no.6
• /
• pp.556-561
• /
• 2020

The aging and declining agricultural population in the modern society requires improvement of the agricultural environment and is one of the representative problems. And since most of the work systems always require a transport work, the ratio of labor consumed in the transport work is very high. Accordingly, many types of transport vehicles are being developed and sold, and in the early days, most of them are powered transport vehicles using fossil fuels. However, it is paying attention to next-generation eco-friendly energy such as hydrogen, fuel cells, solar power, and bio due to the strengthening of international environmental regulations such as global warming and the Convention on Climate Change and the depletion of fossil fuels. Therefore, in this study, the ultimate goal is to develop an eco-friendly, easy-to-operate, safe agricultural electric vehicle that replaces fossil fuels. It was designed with a focus on controlling a wide range of vehicle speeds and securing stability of electric agricultural vehicles. Considering the performance and design, it is composed of a frame, a driving part, a steering part, and a controller system, and we are going to review and manufacture each part. It is believed that the manufactured electric vehicle for agriculture can be easily and conveniently operated in an agricultural society where young manpower is scarce, and can be helpful to the agricultural society through high efficiency.

• Korean Journal of Construction Engineering and Management
• /
• v.16 no.1
• /
• pp.24-34
• /
• 2015

As recent multilateral collaboration design system has been advanced, BIM based data exchange is a key factor for successful next generation building project. Even though many studies have been trying to set up a data compatibility system for collaboration, There are still a lot of problem in data exchange between design and engineering phase. Therefore, In this study, we analysis causes of problem for information exchange and suggest a IFC based Information exchange framework for improving BIM based design collaboration environment. In order to find out problems that hinder establishment of advanced open BIM information exchange, proper analysis about transition of process from current and to-be BIM based design collaboration process is important, at first. From analysis of main obstacles to information exchange, this research suggests solution plan using open API and IFC based BIM collaboration supporting system. The suggested open API solution named Integrity feedback system perform a role making up for weak point derived from IFC based data exchange. And main system suggestion about framework for IFC based information exchange reflect technological system support, requirement of function for collaboration including API/BCF plug-in.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.3
• /
• pp.24-31
• /
• 2020

Centralized systems in computing environments have various problems, such as privacy infringement due to hacking, and the possibility of privacy violations in case of system failure. Blockchain, one of the core technologies for the next generation of converged information, is expected to be an alternative to the existing centralized system, which has had various problems. This paper proposes a blockchain-based user authentication system that can identify users using EID in an online environment. Existing identification (ID)/password (PW) authentication methods require users to store personal information in multiple sites, and receive and use their respective IDs. However, the proposed system can be used without users signing up at various sites after the issuing of an EID. The proposed system issues an EID with a minimum of information, such as an e-mail address and a telephone number. By comparing the stability and efficiency of a centralized system, the proposed integrated authentication system proved to be excellent. In order to compare stability against existing systems, we chose attack methods and encroachments on the computing environment. To verify efficiency, the total throughput between the user's app, the issuance and certification-authority's servers, and the service provider's servers was compared and analyzed based on processing time per transaction.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.12C
• /
• pp.1020-1028
• /
• 2010

Relay has attracted great attention due to its inherent capability to extend the service coverage and combat shadowing in next generation mobile communication systems. So far, most relay technologies have been developed under the half-duplex (HD) constraint that prevents relays from transmitting and receiving at the same time. Although half-duplex relay (HDR) is easy to implement, it requires partitioning of resource for transmission and reception, reducing the whole system capacity. In this paper, we propose a multinser precoding and power control scheme with sum rate matching for a full-duplex (FD) multiple-input multiple-output (MIMO) relay. Full-duplex relay (FDR) can overcome the drawback of HDR by transmitting and receiving on the same frequency at the same time, while it is crucial to reduce the effect of self-interference that is caused by its own transmitter to its own receiver. The proposed precoding scheme cancels the self-interference of the FDR as well as to support multiuser MIMO. Moreover, we suggest a power allocation scheme for FD MIMO relay with the constraint that the sum rate of the relay's received data streams is equal to that of the relay's transmit data streams.

• Proceedings of the Korea Contents Association Conference
• /
• 2006.11a
• /
• pp.42-46
• /
• 2006

As the next generation internet (NGI) is supporting High-speed in Gbps rate with the appearance of advanced network technologies, various applications that require high data rates. have been experimented and operated. By using high speed application services, many kinds of problems can be generated but we cannot easily grasp their reasons. However, if the user monitors the end-to-end one's flow data information (path and data rate in each router, state of each router) he can find them more accurately Until now, we have found out the fact that systems which can network-widely monitor end-to-end flow have not be developed yet, only simple systems which can monitor user's individual flow data at just one node are developed In this study, we suggest and materialize a system which can analyze bandwidth in real time by searching routing paths and measuring packet transfer rate between end-to-end flow data and supported flow traffic of using IPv6.

• The Journal of the Korea Contents Association
• /
• v.13 no.6
• /
• pp.9-19
• /
• 2013

In this paper, we develop a Spatio-Temporal graph as of a key component of our knowledge representation Scheme. We design an integrated representation scheme to depict not only present and past but future in parallel with the spaces in an effective and intuitive manner. An event in general occupies not only a space but a time. Hence a crucial premise for the simulation of virtual situations is to position events in the multi-dimensional context, that is, 3-D space extended by the temporal dimension. Furthermore an event tends to have physical, social and mental aspects intertwined. As a result we need diverse information structures and functions to model entities and relations associated with events and to describe situations in different stances or perspectives of the virtual agents. These structures and functions are implemented in terms of integrated and intuitive representation schemes at different levels such as Ontology View, Instance View, ST View, Reality View. The resulting multi-dimensional comprehensive knowledge structure accommodates multi-layered virtual world developing in the time to maximize the diversity of situations in the historical context. The viability of this knowledge representation scheme is demonstrated with a typical scenario applied to a simulator implemented based on the ST Graph. The virtual stage based on the ST graph can be used to provide natural contexts for situated learning or next-generation simulation games.

• Journal of Satellite, Information and Communications
• /
• v.11 no.3
• /
• pp.58-64
• /
• 2016

This paper proposes the efficient transmit antenna selection (TAS) scheme considering trade-off between the performance and the complexity in massive MIMO system. The massive MIMO system is a core technology to achieve performance objectives for 5 generation wireless communication. It achieve high spectral efficiency, a reliability, and a diversity gain. However many RF chains required by massive transmit antennas equipped in a base station create the problem such as high hardware cost and complexity. Therefor we investigates the transmit antenna selection scheme, in which the number of RF chains of BS is reduced, and the trade-off between the performance and the complexity is considered for proposed scheme. And, the spectral efficiency and complexity are analysed by transmit antenna selection schemes.