• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.651-658
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• 2020

In the fifth generation (5G) mobile networks, the interactive mobile game users have increased tremendously, which induces correlated information sources (CIS). One of the promising 5G technologies is non-orthogonal multiple access (NOMA). In NOMA, the users share the channel resources, so that CIS affect each user's bit-error rate (BER) performance, which is not the case for orthogonal multiple access (OMA). In this paper, we derive the optimal receiver for NOMA with CIS, and then investigate the impact of CIS on each user's BER performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.846-849
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• 2011

The management system using the current RFID technology has the effects of reducing working hours and improvement in data processing, but it is not proper for human resource allocation since it is dominantly worked for physical resources. In this paper, we analyzed personnel control system using RFID of diverse environment and kinds of design in ship which analyzes presents of a monitoring system for safety operation and increase of efficiency in order to overcome the limitations and problems of current personnel operation management techniques using RFID.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.472-480
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• 2011

In this paper, we investigate two new candidate transmission schemes, non-orthogonal frequency reuse (NOFR) and beam-hopping (BH). They operate in different domains (frequency and time/space, respectively), and we want to know which domain shows overall best performance. We propose a novel formulation of the signal-to-interference plus noise ratio (SINR) which allows us to prove the frequency/time duality of these schemes. Further, we propose two novel capacity optimization approaches assuming per-beam SINR constraints in order to use the satellite resources (e.g., power and bandwidth) more efficiently. Moreover, we develop a general methodology to include technological constraints due to realistic implementations, and obtain the main factors that prevent the two technologies dual of each other in practice, and formulate the technological gap between them. The Shannon capacity (upper bound) and current state-of-the-art coding and modulations are analyzed in order to quantify the gap and to evaluate the performance of the two candidate schemes. Simulation results show significant improvements in terms of power gain, spectral efficiency and traffic matching ratio when comparing with conventional systems, which are designed based on uniform bandwidth and power allocation. The results also show that BH system turns out to show a less complex design and performs better than NOFR system specially for non-real time services.

• International Journal of Contents
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• v.14 no.2
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• pp.1-6
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• 2018

In a wireless mobile communication system, a pilot signal has been considered to be a necessary signal for estimating a changing channel between a base station and a terminal. All mobile communication systems developed so far have a specification for transmitting pilot signals. However, although the pilot signal transmission is easy to estimate the channel,(Ed: unclear wording: it is easy to use the pilot signal transmission to estimate the channel?) it should be minimized because it uses radio resources for data transmission. In this paper, we propose a pilotless channel estimation scheme (PCE) by introducing the clustering method of unsupervised learning used in our deep learning into channel estimation.(Ed: highlight- unclear) The PCE estimates the channel using only the data symbols without using the pilot signal at all. Also, to apply PCE to a real system, we evaluated the performance of PCE based on the resource block (RB), which is a resource allocation unit used in LTE. According to the results of this study, the PCE always provides a better mean square error (MSE) performance than the least square estimator using pilots, although it does not use the pilot signal at all. The MSE performance of the PCE is affected by the number of data symbols used and the frequency selectivity of the channel. In this paper, we provide simulation results considering various effects(Ed: unclear, clarify).

• Journal of the Korean Institute of Landscape Architecture
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• v.22 no.1
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• pp.1-16
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• 1994

This paper examines the individual and social values of tour and recreation activities related to the characteristics and attractions of parks in urban area through a questionnaire. The data for this research consists of 2,942 samples based on interviews in sixteen parks in Daegu area. Implications of the findings for urban parks design and tour and recreation policy are discussed. Travel cost method and contingent valuation method are applied essentially. These methods yield a reasonable estimation of the relationship between tour and recreation values of the parks and the visit rate which can be used to estimate demand functions for tour and recreation experiences provided by a site. Semilog-type models can be used to estimate the use of the park. Finally, the tour and recreation value of each park per user-day is estimated by the total experiences of the users. This study is a modest but important step in the investigation of urban parks and recreation site demand and values. Many of the developments in contingent valuation method and travel cost modeling should now be applied to the urban scale parks and recreation sits. Such studies will contribute significantly to the improvement of methodology for tour and recreation values measuring, especially to individual and social benefits for the urban parks, and provide the much needed guidance for the allocation of scarce tour and recreation resources.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.6
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• pp.1032-1037
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• 2006

The channel is one of the precious and limited resources in wireless networks. There are many researches on the channel management. Recently, the optimization problem of guard channels has been an important issue. In this paper, we propose an intelligent channel management technique based on the neural networks. An SRN channel allocation model is developed to generate the learning data for the neural networks and the performance analysis of system. In the proposed technique, the neural network is trained to generate optimal guard channel number g, using backpropagation supervised learning algorithm. The optimal g is computed using the neural network and compared to the g computed by the SRM model. The numerical results show that the difference between the value of 8 by backpropagation and that value by SRM model is ignorable.

• Journal of Navigation and Port Research
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• v.31 no.2
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• pp.141-149
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• 2007

The competitiveness of container terminals hinges on minimizing the time vessels spend in port and on schedule services. Many previous researches on container terminals have tried to optimize the equipment allocation plan and to improve the activity of resources. Nevertheless, there have been few researches conducted on yard tractors, which move containers between the quay and the yard. The aim of this study is to propose the use of Real Time Location Systems (RTLS) based Dynamic Planning for yard tractors. Only RFID (Radio Frequency Identification) tags, which are attached to yard tractors, are able to support RTLS implementation. The system can provide real time job ordering in terms of load balancing using the information on location, in regards to the movement of yard tractors. This study will present the practical feasibility of RTLS, which can ultimately reduce the congestion of Hot Queues in container terminals. As a result, container terminals can be more productive and competitive. In order to accomplish the purpose of this study, we examined previous studies on the competitiveness of container terminals and summarized the potential of RTLS using RFID. In addition, we identified the role of yard tractors and proposed the two rules of Dynamic Planning for the yard tractors. We then fulfilled computational experiments on how yard tractors carrying containers by RTLS ordering Finally, the benefits and the implications of this study are discussed.

• Journal of Information Processing Systems
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• v.10 no.4
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• pp.491-502
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• 2014

In this paper we present some research results on computing intensive applications using modern high performance architectures and from the perspective of high computational needs. Computing intensive applications are an important family of applications in distributed computing domain. They have been object of study using different distributed computing paradigms and infrastructures. Such applications distinguish for their demanding needs for CPU computing, independently of the amount of data associated with the problem instance. Among computing intensive applications, there are applications based on simulations, aiming to maximize system resources for processing large computations for simulation. In this research work, we consider an application that simulates scheduling and resource allocation in a Grid computing system using Genetic Algorithms. In such application, a rather large number of simulations is needed to extract meaningful statistical results about the behavior of the simulation results. We study the performance of Oracle Grid Engine for such application running in a Cluster of high computing capacities. Several scenarios were generated to measure the response time and queuing time under different workloads and number of nodes in the cluster.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.203-228
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• 2012

It is expected that device-to-device (D2D) communication is allowed to underlay future cellular networks such as IMT-Advanced for spectrum efficiency. This article studies the mechanisms of D2D communication and interference avoidance when the D2D subsystem reuses uplink resources and downlink spectrums with a cellular system, respectively. We firstly propose an effective scheme to establish and maintain D2D communication. Moreover, a novel method to deal with the resource allocation and interference avoidance issues by utilizing the network peculiarity of a hybrid network to share the uplink resource is proposed. Most research focuses on reusing the uplink spectrums, but how to share the downlink frequency bands is seldom addressed. To share the downlink spectrums and avoid the interference to the primary cellular devices, a labeled time slots based mechanism is proposed. Implementation details are described in a real cellular system and simulation results prove that satisfying performance can be achieved by using the proposed mechanisms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.4133-4145
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• 2017

Advances in science and technology are driving us to the better life but also forcing us to make more investment at the same time. Therefore, the government has provided the investment to carry on the promising futuristic technology successfully. Indeed, a lot of resources from the government have supported into the science and technology R&D projects for several decades. However, the performance of the public investments remains unclear in many ways, so thus it is required that planning and evaluation about the new investment should be on data driven decision with fact based evidence. In this regard, the government wanted to know the trend and issue of the science and technology with evidences, and has accumulated an amount of database about the science and technology such as research papers, patents, project reports, and R&D information. Nowadays, the database is supporting to various activities such as planning policy, budget allocation, and investment evaluation for the science and technology but the information quality is not reached to the expectation because of limitations of text mining to drill out the information from the unstructured data like the reports and papers. To solve the problem, this study proposes a practical text mining methodology for the science and technology trend analysis, in case of aerospace technology, and conduct text mining methods such as ontology development, topic analysis, network analysis and their visualization.