• Journal of Intelligence and Information Systems
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• v.12 no.3
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• pp.67-82
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• 2006

We propose the HBEM(Hybrid Behavior Evolution Model) composed of rule classification and evolutionary neural network using rule descriptor and link descriptor for evolutionary behavior of virtual robots. In our model, two levels of the knowledge of behaviors were represented. In the upper level, the representation was improved using rule and link descriptors together. And then in the lower level, behavior knowledge was represented in form of bit string and learned adapting their chromosomes by the genetic operators. A virtual robot was composed by the learned chromosome which had the best fitness. The composed virtual robot perceives the surrounding situations and they were classifying the pattern through rules and processing the result in neural network and behaving. To evaluate our proposed model, we developed HBES(Hybrid Behavior Evolution System) and adapted the problem of gathering food of the virtual robots. In the results of testing our system, the learning time was fewer than the evolution neural network of the condition which was same. And then, to evaluate the effect improving the fitness by the rules we respectively measured the fitness adapted or not about the chromosomes where the learning was completed. In the results of evaluating, if the rules were not adapted the fitness was lowered. It showed that our proposed model was better in the learning performance and more regular than the evolutionary neural network in the behavior evolution of the virtual robots.

• Journal of the Korea Society of Computer and Information
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• v.20 no.6
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• pp.29-35
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• 2015

The heterogeneous LTE (Long Term Evolution)-Advanced networks comprising a macrocell and femtocells can provide an efficient solution not only to extend macrocell coverage but also to deal with packet traffics increasing explosively within macrocells. An efficient resource management scheme is necessary to maintain the QoS (Quality of Service) of mobile multimedia services because the LTE-Advanced system should support not only voice but also mobile applications such as data, image and video. This paper proposes a resource management scheme to guarantee QoS continuity of multimedia services and to maximize the resource utilization in OFDMA (Orthogonal Frequency Division Multiple Access) based LTE-Advanced systems. This scheme divides the resources into several service blocks and allocates those resources based on the competition between macrocell and femtocell. Simulation results show that it provides better performances than the conventional one in respect of handover failure rate and blocking rate.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.91-98
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• 2012

Since the major cellular data service providers in U.S, Japan as well as in Korea started the LTE (Long Term Evolution) service, there has been more strong need for the methods that can accurately measure the MIMO (Multi Input-Multi Output) OTA (Over The Air) performance of LTE handsets because the performance of the MIMO antenna determines the data throughput in the downlink. In this paper, the hand effect on the MIMO antenna performance is analyzed by numerically and experimentally. The hand effect on the LTE mobile handset is analyzed by measuring the link level performance in the MIMO OTA system.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.4
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• pp.36-42
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• 1998

It is difficult to construct a controller for a mobile robot so that it can adapt appropriately in dynamicallychanging environment. To solve this problem, extensive research has been actively performedto construct a controller by evolutionary method, but few results has come out about the behavioraln~echanism of the evolutionarily constructed controller. This paper attemps to systematically analyze themechanism of the controller constructed by evolution. As a result, we have found that evolution canproduce a controller that can solve a given problem properly, where given problem is divided into severalsub problems and adequate mechanisms emerge for each sub problem. The whole problem hasbeen solved through the complicated interactions of these mechanisms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.383-403
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• 2021

With the development of mobile edge computing (MEC), some late-model application technologies, such as self-driving, augmented reality (AR) and traffic perception, emerge as the times require. Nevertheless, the high-latency and low-reliability of the traditional cloud computing solutions are difficult to meet the requirement of growing smart cars (SCs) with computing-intensive applications. Hence, this paper studies an efficient offloading decision and resource allocation scheme in collaborative vehicular edge computing networks with multiple SCs and multiple MEC servers to reduce latency. To solve this problem with effect, we propose a context-aware offloading strategy based on differential evolution algorithm (DE) by considering vehicle mobility, roadside units (RSUs) coverage, vehicle priority. On this basis, an autoregressive integrated moving average (ARIMA) model is employed to predict idle computing resources according to the base station traffic in different periods. Simulation results demonstrate that the practical performance of the context-aware vehicular task offloading (CAVTO) optimization scheme could reduce the system delay significantly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.960-967
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• 2006

Mobile communication is evolving toward next generation system that is capable to provide ubiquitous human-centric services with giving no restriction on time and location. In particular, context-awareness will be realized using various sensors and devices and related technologies under the ubiquitous Next Generation (NG) mobile communications environment where user's demand and surrounding context are changing dynamically. By such context awareness, context aware service which provides best suitable services for a user by analyzing user's needs and situational information, will be one of the promising NG mobile services. In this article, we propose NG mobile service environment with focusing on generic service traffic flows supported by the NG service platform which gives various means of connecting users and service providers. Then, we propose evolutional phases of context-aware services based on ranges of context information and evolutional trend of telecommunication technologies and networking environment in NG mobile service environment.

• Journal of Digital Contents Society
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• v.6 no.2
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• pp.131-135
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• 2005

Nowadays, the demand for the wireless technology has gradually increased to support the services of high speed wired internet and also the interest of a mobile terminal convergence has increased. In the next generation, the mobile terminal could merge with the celluar phone, wireless LAN, portable internet, digital multimedia brodcasting, mobile game and sensor(smart-tag and biometrics) through the unified single user interface. Moreover, the system is supported to multi-mode at difference networks, which have variable functions and high performance for available service. Inthis paper, we investigate the minimum requirements and the core technologies of the next generation mobile terminals.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.3
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• pp.8-15
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• 2010

Due to the increasing demand of network convergence, in future, hybrid/integrated satellite and terrestrial systems will play an important role. In that case, compatibilities between the satellite and terrestrial systems are very important for efficiency of the systems. 3GPP Long Term Evolution (LTE) is one of the most powerful candidates of the 4G system Therefore, in this paper, we introduce the design of interleaver for mobile satellite system based 3GPP LTE specification. The 4G system including the LTE specification adopted adaptive modulation and coding (AMC) schemes for efficient usage of resources, and the updating interval of resource allocation is an order of msec. However, because of the long round trip delay of satellite systems, we cannot employ the same AMC scheme specified for the terrestrial system, and thus it cannot effectively counteract to short term fadings. Therefore, in order to overcome these problems, we propose an interleaver scheme combined with AMC. We present the interleaγer design results considering mobile satellite system based on the LTE and analyze the simulation results.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.2
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• pp.131-137
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• 2006

In swarm robot systems, each robot must behaves by itself according to the its states and environments, and if necessary, must cooperates with other robots in order to carry out a given task. Therefore it is essential that each robot has both learning and evolution ability to adapt the dynamic environments. In this paper, the new learning and evolution method based on reinforcement learning having delayed reward ability and distributed genetic algorithms is proposed for behavior learning and evolution of collective autonomous mobile robots. Reinforcement learning having delayed reward is still useful even though when there is no immediate reward. And by distributed genetic algorithm exchanging the chromosome acquired under different environments by communication each robot can improve its behavior ability. Specially, in order to improve the performance of evolution, selective crossover using the characteristic of reinforcement learning is adopted in this paper. we verify the effectiveness of the proposed method by applying it to cooperative search problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.2
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• pp.105-114
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• 2013

Expansion and growth of body information monitoring service based on WBAN technology speeds up technological evolution in bio-signal detection and measurement, real time monitoring of vital sign and telemedicine control. It is essential for taking action against such technological evolution that newest technology trend and standardization issue should be included in designing and materializing body-information monitoring system strategically to secure preceding technology and to preoccupy market. This paper investigates and analyzes technological trend & issues, and suggests task to take action technologically.