• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.103-105
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• 2001

국토정보화의 기반준비 단계인 ‘1차 국가 GIS 사업’기간 동안, 상당량의 수치화된 공간 정보가 축적되었고 이들을 관리하기 위한 다양한 종류의 지리정보시스템이 국가기관에서 사용되었다. 그러나, 사용중인 지리정보시스템은 조직적 지리적으로 분산되어 있으며, 공간데이타베이스의 이질성 및 폐쇄성으로 인해, 공간정보의 상호운용 측면에서 한계성을 드러내고 있다. 본 연구에서는 이러만 한계점을 극복하고자 분산 이기종 공간데이타베이스에 저장된 공간정보를 표준화된 방법으로 통합검색하며, 상호운용 가능토록 하는 국가공간정보유통체계를 설계 및 구현한다. 본 시스템을 구성하고 있는 단일 유통게이트웨이, 복수개의 유통노드, 지리정보공급기관을 국가통신망을 통하여 상호 연결하고, 컴퓨팅 부하를 분산시키기 위한 방안으로 공간정보유통망을 검색망 및 전송망으로 분리 설계한다. 검색망에서는 메타데이타의 검색 및 전송을 위한 표준화된 방법으로서 OpenGIS OLE DB Provider 기반 데이터제공자 컴포넌트를 구현한다. 또한 데이터제공자 컴포넌트를 통해 전송된 이기종 공간데이타베이스로부터의 WKB 형태의 공간정보를 상호운용할 목적으로, 공간데이타 구조와 처리에 대한 인터페이스 표준화를 실시한 MapBase 컴포넌트를 활용하여 공간정보에 대한 통합검색, 분석 및 상호운용을 구현한다.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.91-96
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• 2014

Since the sensors of Internet of Things (IOT) collect various data, the lifetime of sensor network is very important and the data should be aggregated efficiently. The contiguous collection by the certain sensors occurs an excessive battery consumption and successive transmission of same value of data should be avoided. To solve these things, we propose an weight-based cluster head replacement method that divides whole network into several grids and cluster head is selected by remaining energy, density of alive sensors and location of sensor. The aim of algorithm maximizes the lifetime of network. Our simulation results shows that the proposed method is very simple as well as balances energy consumption.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.767-768
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• 2009

현재 웹상에서 데이터 표현을 위한 XML의 사용이 늘어나면서, XML 문서의 효율적인 질의 처리에 대한 관심이 증가하고 있다. 기존에 질의 처리 연구는 단일 경로에 대한 질의 처리가 연구되었고, 최근에는 두 개 이상의 경로를 가지는 Twig Pattern 질의 처리 연구가 이루어졌다. 따라서 본 논문에서는 기존에 제안된 기법들 보다 효율적으로 Twig Pattern 질의 처리를 할 수 있는 O-TJFast (Optimal TJFast) 기법을 제안한다. 또한, 본 논문에서는 XML 문서의 파싱(parsing)시 제공되는 정보를 가공하여 스트림과 포인터 구조를 얻어내어 기존에 제안된 기법들 보다 입출력 시간(I/O Time)과 처리 시간(Execution Time)을 효율적으로 감소시킬 수 있는 기법을 제안한다. 그리고 성능평가를 통해 제안한 기법이 처리시간에 많은 이득을 볼 수 있음을 보인다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.33-44
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• 2008

Multipath routing protocols with load balance, fault tolerance, aggregated bandwidth in Ad-hoc Networks provide improved throughput and reliable route as compared with singlepath routing protocols. However, multipath routing protocols have not been explored thoroughly in the domain of overhead in Ad-hoc Networks. In this paper, we analyze and compare on-demand singlepath and multipath routing with IEEE 802.11 DCF in terms of Routing overhead and MAC overhead. The results reveals that in comparison with singlepath routing protocol, multipath routing mechanism creates more overheads but provides better performance in congestion and capacity provided that the route length is within a certain upper bound which is derivable. The analytical results are further confirmed by simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.188-194
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• 2011

We analyze transmission performance of radio frequency signal in WDM-ROF (wavelength division multiplexing - radio over fiber) system employing photonic crystal fiber. In a WDM-ROF system employing conventional single-mode fiber, transmission performance of radio frequency signal is analyzed depending on each WDM channel. In this case, each WDM channel experiences power fluctuation of received RF signal in remote node because of double sidebands of the modulated signal and wavelength dependent dispersion of single mode fiber. This RF power fluctuation acts as a design constraint in viewpoint of system design. By employing photonic crystal fiber (PCF) with dispersion compensation characteristics, the transmission performance of RF signal can be improved compared with the case with SMF only.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.289-296
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• 2008

In wireless mesh network, studies on routing protocols have been actively carried out recently, and hop count is used as a major routing metric in destination-sequenced distance-vector (DSDV) routing protocol, which is a representative proactive routing protocol. Although hop-by-hop multi-path (HMP) DSDV and enhanced HMP (EHMP) DSDV routing protocols perform routing by considering both hop count and residual bandwidth within one hop distance nodes, it has a shortcoming that routing is carried out via non-optimal path from the aspect of end-to-end routing. In order to overcome the shortcoming, a cost-aware multi-path (CAMP) DSDV routing protocol is proposed in this paper, which considers hop count and end-to-end minimum residual bandwidth. Simulation results based on NS-2 show that the proposed routing protocol performs better than DSDV, HMP DSDV, and EHMP DSDV protocols from the aspect of throughput and packet delivery ratio, by appropriately using hop count and end-to-end minimum residual bandwidth information and has the same number of management messages with HMP DSDV and EHMP DSDV protocols.

• The Journal of the Korea Contents Association
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• v.12 no.10
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• pp.1-10
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• 2012

Many statistical methods have been adapted for terminology recognition to improve its accuracy. However, since previous studies have been carried out in a single core or a single machine, they have difficulties in real-time analysing explosively increasing documents. In this study, the task where bottlenecks occur in the process of terminology recognition is classified into linguistic processing in the process of 'candidate terminology extraction' and collection of statistical information in the process of 'terminology weight assignment'. A terminology recognition system is implemented and experimented to address each task by means of the distributed parallel processing-based MapReduce. The experiments were performed in two ways; the first experiment result revealed that distributed parallel processing by means of 12 nodes improves processing speed by 11.27 times as compared to the case of using a single machine and the second experiment was carried out on 1) default environment, 2) multiple reducers, 3) combiner, and 4) the combination of 2)and 3), and the use of 3) showed the best performance. Our terminology recognition system contributes to speed up knowledge extraction of large scale science and technology documents.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.11
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• pp.385-392
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• 2016

Recently, Expectation Area-based Real-time Routing (EAR2) protocol has been proposed to support real-time routing in wireless sensor networks. EAR2 considers the expectation area of a mobile sink and uses flooding within the expectation area. However, flooding leads to excessive energy consumption and causes long delay against real-time routing. Moreover, since EAR2 uses single path to the expectation area, it is difficult to support reliable routing in sensor networks with high link failures. Thus, to overcome these limitation of EAR2, this paper proposes a reliable and real-time routing protocol based on virtual grids and multipath for mobile sinks. To support real-time routing, the proposed protocol considers expectation grids belonged to the expectation area. Instead of flooding within the expectation area, the proposed protocol uses multicasting to the expectation grids and single hop forwarding in an expectation grid because the multicasting can save much energy and the single hop forwarding can provide short delay. Also, the proposed protocol uses multipath to the expectation grids to deal with link failures for supporting reliable routing. Simulation results show that the proposed protocol is superior to the existing protocols.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.4
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• pp.338-347
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• 2021

In this paper, the beta-ray sensor circuit used in the true random number generator was designed using DB HiTek's 0.18㎛ CMOS process. The CSA circuit proposed a circuit having a function of selecting a PMOS feedback resistor and an NMOS feedback resistor, and a function of selecting a feedback capacitor of 50fF and 100fF. And for the pulse shaper circuit, a CR-RC2 pulse shaper circuit using a non-inverting amplifier was used. Since the OPAMP circuit used in this paper uses single power instead of dual power, we proposed a circuit in which the resistor of the CR circuit and one node of the capacitor of the RC circuit are connected to VCOM instead of GND. And since the output signal of the pulse shaper does not increase monotonically, even if the output signal of the comparator circuit generates multiple consecutive pulses, the monostable multivibrator circuit is used to prevent signal distortion. In addition, the CSA input terminal, VIN, and the beta-ray sensor output terminal are placed on the top and bottom of the silicon chip to reduce capacitive coupling noise between PCB traces.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.3
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• pp.155-164
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• 2016

For frequency pattern analysis of large databases, the new tree-based frequency pattern analysis algorithm which can compensate for the disadvantages of the Apriori method has been variously studied. In frequency pattern tree, the number of nodes is associated with memory allocation, but also affects memory resource consumption and processing speed of the growth. Therefore, reducing the number of nodes in the tree is very important in the frequency pattern mining. However, the absolute criteria which need to order the transaction items for construction frequency pattern tree has lowered the compression ratio of the tree nodes. But most of the frequency based tree construction methods adapted the absolute criteria. FP-tree is typically frequency pattern tree structure which is an extended prefix-tree structure for storing compressed frequent crucial information about frequent patterns. For construction the tree, all the frequent items in different transactions are sorted according to the absolute criteria, frequency descending order. CanTree also need to absolute criteria, canonical order, to construct the tree. In this paper, we proposed a novel frequency pattern tree construction method that does not use the absolute criteria, IRFP-tree algorithm. IRFP-tree(Intersection Rule based FP-tree). IRFP-tree is constituted with the new paradigm of the intersection rule without the use of the absolute criteria. It increased the compression ratio of the tree nodes, and reduced the tree construction time. Our method has the additional advantage that it provides incremental mining. The reported test result demonstrate the applicability and effectiveness of the proposed approach.