• 전기의세계
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• v.24 no.4
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• pp.80-82
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• 1975

This paper presents a synthesis procedure of multi-channel active filters, which realizes an arbitrary N*N matrix of real rational functions in the complex variable s as a voltage transfer matrix. The resultant network reveals a transformerless grounded active RC(2N+1)-terminal network. The active network is consisted of six 2N-port RC networks with 2N single-ended operational amplifiers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.1-5
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• 2004

In this paper, we propose a novel approach for evolving the architecture of a multi-layer neural network. Our method uses combined ART1 algorithm and Max-Min neural network to self-generate nodes in the hidden layer. We have applied the. proposed method to the problem of recognizing ID number in student identity cards. Experimental results with a real database show that the proposed method has better performance than a conventional neural network.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.2
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• pp.117-130
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• 2012

Due to the development of network and device, it is called mobile age that boosts various distribution routes of multi-media content and it constructs a new digital content consumption trend. N-screen is one of the new-introduced examples in the digital age and broadcasting industry believes it as a crisis and challenge as well. It becomes a ubiquitous multi-media environment that people watch multi-media content everywhere and any time they want to and competition happens beyond the boundaries such as network industry, terminal industry, pay TV market, traditional terrestrial TV, etc. And then how should the broadcasting service prepare for the N-screen business? The present research proposes a few terrestial broadcasting content strategies in the multi platform environment. First, instead of N-screen, it proposes multi platform, especially One Source Multi Platform(OSMP). Second, so-called 'Integrated Terrestrial Broadcasting OSMP Alliance(IBPA)' must be founded. Third, IBPA should support multi-tasking UX for viewers to have rich experience. Last, it becomes more important and necessary to support local terrestrial broadcasting service for public service in the multi platform age.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.3
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• pp.440-448
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• 2021

This paper presents problems of network technology in smart grid and implements a blockchain-based LoRa multi-hop network to solve them. Since some smart grid applications are operated in harsh environments, it is difficult to establish communication infrastructure. We propose a LoRa network with multi-hop using the Flooding routing protocol. Smart grid environment composes an independent network using various power grid protocols depending on the application. Since this has a problem that an independent infrastructure must be established for each network, a single gateway device supports multiple power grid protocols to implement a method for network integration. Lastly, the author applied Hyperledger-based blockchain to the LoRa network to ensure the integrity of data in a smart grid environment, and strengthened security by physically distributing it. After constructing the three suggestions on the actual test bed, we confirmed that the network operates normally through experiments.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.7
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• pp.1-8
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• 2012

In this paper, we consider an efficient protocol for the multi-hop relay transmission on a sensor network which can be utilized in a ubiquitous environment. More specifically, we propose an efficient relaying protocol for the distance and position recognition on the proposed sensor network which performs with the differentially bi-orthogonal chirp spread spectrum (DBO-CSS) in the industrial, scientific and medical (ISM) bands. For an efficient networking access, we design and implement four different packet structures, zone information packet, hop information packet, tag information packet, and application serial packet. Additionally, we also propose an efficient position recognition algorithm. Finally, for verification of our proposed protocol's efficiency, we build the testbed system which consists of $15m{\times}15m$ multi-cell and 10 hops in the network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.401-410
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• 2014

This paper presents a high-efficiency concurrent dual-band Class-E power amplifier(PA) that is based on a multi-harmonic matching network(MHMN). The proposed MHMN controls the impedance at 1.3 GHz, 2.1 GHz, and their second and third harmonics, respectively, by using transmission lines only rather than switches or lumped components. The dual-band Class-E PA is implemented using Avago ATF-50189 GaAs p-HEMT. The PA exhibits a measured output power of 27.1 dBm and 25.7 dBm, a power gain of 6.1 dB and 4.7 dB, and a drain efficiency of 71.2 % and 60.1 % at 1.3 GHz and 2.1 GHz, respectively.

• Journal of Internet Computing and Services
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• v.12 no.2
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• pp.113-122
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• 2011

Social Network Service(SNS) has become a hot trend as a web service which helps users construct social relationships in the web and enables online communication. The information about user activities and behaviors obtained from the SNSs is expected to be an useful knowledge source for other services such as recommendation services. Most of previous researches on SNS rely on analyzing overall network topology and surveying the activities in a one-dimensional aspect. This paper propose a system for measuring multi-dimensional interaction through the activities in a SNS. The proposed system delivers an unified profile (consisting of profile and multi-dimension interaction) model from user-activities in Twitter.com. At the experimental section, some meaningful perspectives on a set of the unified profiles are described.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2843-2852
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• 2013

In the nested mobile network environment, the mobile node selects one of multiple mobile routers. The MR(Mobile Router) by existing top-down or bottom-up methods may not be the optimal MR if the numbers of mobile nodes and routers are substantially increased, and the scale of the network is increased drastically. Since an inappropriate MR decision causes handover or binding renewal to mobile nodes, determining of the optimal MR is important for efficiency. In this paper, we propose an algorithm that decides on the optimal MR using MR QoS(Quality of Service) information, and we describe how to understand the various structured MLP(Multi-Layered Perceptron) based on the algorithm. In conclusion, we prove the ability of the suggested neural network for a nesting mobile network through the performance analysis of each learned MLP.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.59-70
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• 2022

Water distribution systems (WDSs) are a representative infrastructure injecting chlorine to disinfect the pathogenic microorganisms and supplying water from sources to consumers. Also, WDSs prescribe to maintain the usual standard (0.1-4.0 mg/L) of residual chlorine. However, the user's usage pattern, water age, network shape, and type affect the hydraulic features (i.e. nodal pressure, pipe velocity) and water quality features (i.e., the residual chlorine concentration). Therefore, this study developed an optimization approach for optimizing WDSs considering water quality-hydraulic factors using Multi-objective Harmony Search (MOHS). The design cost and the system resilience were applied as the design objective functions, and the nodal pressure and the concentration of residual chlorine are used as constraints. The derived optimal designs through this approach were analyzed according to network characteristics such as the network shapes and type. These optimal designs can meet the safety of economic and water quality aspects to increase user acceptance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4259-4271
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• 2016

With the increased popularity of IEEE 802.11 WLAN, the density of the WLAN devices per access point has also increased, resulting in throughput performance degradation. One of the solutions to the problem is improving the protocol efficiency by a using multi-round contention scheme. This paper first discusses how to estimate the number of contending stations in a WLAN network by using minimum elapsed backoff counter values that can be easily monitored by each station. An approximate closed form expression is derived for the number of active contending stations using the smallest backoff counter value in the network. We then apply this result to adapt the number of contending rounds according to the network loading level to enhance the throughput performance of a multi-round contention scheme. Through simulation, we show that the accuracy of the estimation algorithm depends on the contention parameters of W and the number of backoff counter observing samples, and found a reasonable value for each parameter. We clearly show that our adaptive multi-round contention scheme outperforms the standard contention scheme that uses a fixed number of rounds.