• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.275-281
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• 2012

Community network is a communication environment where heterogeneous devices can access and communicate with each other at any time and at any space to share information. To do so, mobile devices are required to be self-configured even in absence of communication infrastructures. Semi-infrastructured wireless ad-hoc network is a promising solution to meet with such a requirement. This paper proposes the VTC(virtual topology coordinator) system as an evaluation tool for examining network protocols that are intended to be deployed in the semi-infrastructured ad-hoc networks. VTC emulates multi-hops wireless network topology virtually using a mechanism of selective receiving MAC frame in a small area, where only a single hop communication is available. VTC system cannot consider all properties introduced in real wireless network, but do more wireless properties than verification through simulation.

• The KIPS Transactions:PartC
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• v.12C no.7 s.103
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• pp.941-948
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• 2005

In the self-healing group key distribution scheme, users are capable of recovering lost group keys on their own without requesting additional transmission from the group manager, where there is no reliable network infrastructure. In this paper, we propose a new self-healing group key distribution scheme with revocation capability, which is optimal in terms of user memory storage and more efficient in terms of communication complexity than the previous results. We obtain a slightly improved result from (13) and (14) by using the new broadcasting method. In addition, we prove that our scheme has the properties of t-wise forward secrecy and t-wise backward secrecy, and extend this self-healing approach to the session key recovery scheme from a single broadcast message.

• Journal of Korea Technology Innovation Society
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• v.11 no.2
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• pp.145-170
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• 2008

The existence of network is indeed the single most important factor that brings about new business phenomena in the new digital economy, especially in the IT industry. Network effect refers to a phenomenon that the increase in size of the network leads to increased network value and user utility. It determines the competitive structure of an industry and the performances of industry competitors (Shapiro and Varian, 1999). The phenomenon of increasing returns and winner-take-all enjoyed by the early winner in the competition can be attributed to the existence of positive feedback which increases the value of network and induces more users into join the network (Arthur, 1996; Shapiro and Varian, 1999; Song and Lee, 2003). This research attempts to shed light on the topic of innovation and competitive strategy of network-based industries. We analyze the case of the Korean mobile communications industry, in which a shift in technological paradigm from 2G to 3G brought new changes to the competitive structure of the industry. The Korean mobile communications industry makes an ideal case for analysis since it is an industry whose value is inherently dependent upon its user network. It is characterized by the typical increasing returns, in which a monopolizing player is enjoying firstmover's network effects. Because of the existence of network in the mobile communications industry, latecomers' disruptive innovations could not outcompete the incumbent's sustaining innovations. The contribution of this research lies in laying a groundwork for future studies by introducing a numerical simulation model to analyze the complexity theory and network effect.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.137-142
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• 2024

Recently, deep learning technology has become those methods as de facto standards in the area of medical data representation. But, deep learning inherently requires a large amount of training data, which poses a challenge for its direct application in the medical field where acquiring large-scale data is not straightforward. Additionally, brain signal modalities also suffer from these problems owing to the high variability. Research has focused on designing deep neural network structures capable of effectively extracting spectro-spatio-temporal characteristics of brain signals, or employing self-supervised learning methods to pre-learn the neurophysiological features of brain signals. This paper analyzes methodologies used to handle small-scale data in emerging fields such as brain-computer interfaces and brain signal-based state prediction, presenting future directions for these technologies. At first, this paper examines deep neural network structures for representing brain signals, then analyzes self-supervised learning methodologies aimed at efficiently learning the characteristics of brain signals. Finally, the paper discusses key insights and future directions for deep learning-based brain signal analysis.

• Knowledge Management Research
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• v.24 no.3
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• pp.195-215
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• 2023

In the telecommunications service industry, until now, it has been possible for Network Operators (NOs) to secure a competitive advantage to increase subscribers and profits through network investment. However, amid a big change to digital economy, network investment fails to lead to increase profits. These days platform companies without holing network infrastructure have a more competitive advantage and take more profits. This makes NOs gradually lose interest in network investment. The purpose of this paper is to find policy measures to promote network investment in digital economy. Specifically, we identify the factors influencing the network investment and promising policy measures energizing the investment, and then analyze their priorities and derive policy implications through Analytic Hierarchy Process (AHP) and Analytic Network Process (ANP). The results of this paper show that market competition is more preferred to public intervention in promoting network investment. However, in order to guarantee and expand the universal access to network, it is necessary to consider expanding the role of the public, focusing on non-economic areas.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.177-178
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• 2014

무선센서네트워크에서 사용되는 혼잡제어 방식은 일반적인 네트워크 방식과는 다르게 고려해야할 사항이 있다. 문제 해결에 사용할수 있는 자원이 한정적이며, 중앙에서 혼잡 제어를 할 경우 지나친 통신 부하가 발생할 수 있다. 본 논문에서는 집단지성(Swarm Intelligence)의 일종인 새 떼의 행동양식을 무선센서네트워크에 적용한 혼잡제어 기법을 살펴보고, 기존 기법에서 발생하는 에너지 소비 불균형을 해결하기 위한 기법에 대해 기술한다. 본 논문을 통해 무선센서네트워크에 새 떼의 간단한 행동양식을 적용함으로써 강인하고 확장 가능하며 자가 적응이 가능한 혼잡제어가 가능함을 확인하고, 집단지성이 우리가 직면하고 있는 다양한 연구 과제의 해결 도구가 될 수 있는 가능성을 보인다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.135-142
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• 2010

Wireless mesh network, which is an access network technology, adopts ubiquitous features of ad-hoc network that includes capabilities of self-configuration and self-management. This paper proposes a scheme which enables nodes along route in wireless mesh network to authenticate data and verify data integrity. The scheme distinguishes infra-node, which is a network device used to form mesh network, and user node in ad-hoc network, which operates functions as a sender, receiver or relayer, to deploy different authentication scheme. That is, hop-based authentication scheme along route forming wireless backbone differs from authentication scheme for user nodes in route over MANET. The proposed scheme is less complex than previously proposed schemes from the repects of security setup procedures and managements. In addition, the scheme is able to reduce transmission delay from a source to a destination owing to fast authentication over wireless backbone.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.603-606
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• 2013

Machine to Machine (M2M) 통신은 수 많은 장비들이 우리 주변환경의 정보를 감지하여 상호간에 주고받는 방법을 활용한다. Third generation partnership project (3GPP)는 이러한 M2M 통신을 활용하여 유비쿼터스 환경과 자가인식형 서비스를 제공하려 하고 있다. 본 논문은 이러한 추세에 맞추어 새로운 개념의 통신인 3GPP M2M 통신의 시스템 구조, 특징들과 이에 대한 3GPP의 연구방향 등에 대한 튜토리얼로 사용될 수 있도록 하기 위해 작성되었다. 특히 M2M 통신에서의 특징들을 구체화하는 과정에서의 보안상 위협과 이에 대처하기 위한 요구사항들에 대해서 강조하였다. 이러한 보안상 위협을 제거하는 요구사항을 만족하면서 네트워크에 과부하를 가하지 않도록 하기 위한 그룹 기반의 최적화된 인증 프로토콜을 제안한다. 본 논문에서는 그룹을 기반으로 bilinear pairing을 사용하여 인증을 진행하며, 통신 딜레이를 줄이고 네트워크의 중심 장비에 과부하를 줄이기 위해 HSS(Home Subscriber Server)의 참여를 제한한 인증 및 키 동의 프로토콜을 제안하고, 이에 따른 연산 및 통신 오버헤드를 분석한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.1-16
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• 2013

Smartphones and tablets including phone, calendar are the necessities of modern man. They are one of the MN(Mobile Node), each with wireless network capabilities. Necessities of modern human MNs are almost included cellular module available in LTE/3G and Wi-Fi module for high-speed Internet. Until now, MN mobility management is handled, but using network-based mobility management in this paper. Then, carriers can manage and maintain the network for low-cost. In addition, it was considered that use a lot of modern people with Wi-Fi and LTE/3G, and using Cross-Layer-Based handoff.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.11
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• pp.463-468
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• 2017

To sense a wide area with mobile nodes, the uniformity of node deployment is a very important issue. In this paper, we consider the coverage problem to sense big data in sparse mobile ad hoc networks. In most existing works on the coverage problem, it has been assumed that the number of nodes is large enough to cover the area in the network. However, the coverage problem in sparse mobile ad hoc networks differs in the sense that a long-distance between nodes should be formed to avoid the overlapping coverage areas. We formulate the sensor coverage problem in sparse mobile ad hoc networks and provide the solution to the problem by a self-organized approach without a central authority. The experimental results show that our approach is more efficient than the existing ones, subject to both of coverage areas and energy consumption.