• Journal of the Korea Society of Computer and Information
• /
• v.12 no.6
• /
• pp.235-242
• /
• 2007

Network Mobility Basic Support protocol reduces location-update signaling by making network movements transparent to the mobile nodes (MNs) behind the mobile router (MR), but causes some problems such as sub-optimal routing and multiple encapsulations. This paper proposes an Route Optimization Employing HMIP Extension for Mobile Networks (ROHMIP) scheme for nested nubile networks support which introduces HMIP concept with relation information between MNNs behind a MR and the MR in order to localize handoff, to optimize routing and especially reduce handoff signal overhead. With ROHMIP, a mobile network node (MNN) behind a MR performs route optimization with a correspondent node (CN) as the MR sends a binding update message (BU) to mobility anchor point (MAP) via root-MR on behalf of all active MNNs when the mobile network moves. This paper describes the new mechanisms and provides simulation results which indicate that our proposal reduces transmission delay, handoff latency and signaling overhead.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.47 no.4
• /
• pp.102-108
• /
• 2010

The photovoltaic system changes solar energy into DC by solar cell and this DC is inverted into AC which is used in general houses by inverter. Recently, the use of power of the photovoltaic system is increased. Therefore, the study of 3 phase solar system to transmit large power is very important. This paper proposes a method that finds simply faults and diagnoses the switch open faults of 3-phase pulse width modulation (PWM) inverter of grid-connected photovoltaic system. The proposed method in $\alpha\beta$ plane uses the patterns of trajectory image as the characteristic parameters and differenciates a normal state and open states of switches. Then, the result is made into tree. The tree is composed of 21 fault patterns and the parameters to classify faults are a shape, a trajectory area, a distributed angle, and a typical vector angle. The result shows that the proposed method diagnosed fault diagnoses, classified correctly them, and made a pattern tree by fault patterns.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.12
• /
• pp.27-37
• /
• 2003

In the next generation Internet(NGI) based on dense wavelength division multiplexing(DWDM) technology, QoS RWA considering various QoS parameters of DWDM networks is regard as one of the key issues in providing real-time multimedia services. However, finding a qualified path meeting multi-constraints is generally NP-complete problem. It is insufficient for QoS RWA researches in DWDM networks that must consider QoS parameter as well as wavelength-continuity constraint. This paper proposes qualified path routing (QPR) algorithm with minimum computation and implementation complexity based on flooding method to accomplish QoS routing and wavelength assignment (RWA). We also introduce a QoS-based RWA mechanism considering multi-constraint such as optical signal quality attributes, survivability and wavelength-continuity constraint combined with proposed routing algorithm. Simulation results show superior efficiency of the proposed algorithms in terms of blocking probability, routing overhead and survivability ratio.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.2B
• /
• pp.183-191
• /
• 2004

Single shortest path routing is known to perform poorly for Internet traffic engineering (TE) where the typical optimization objective is to minimize the maximum link load. Splitting traffic uniformly over equal cost multiple shortest paths in OSPF and IS-IS does not always minimize the maximum link load when multiple paths are not carefully selected for the global traffic demand matrix. However, among all the equal cost multiple shortest paths in the network, a set of TE-aware shortest paths, which reduces the maximum link load significantly, can be found and used by IP routers without any change of existing routing protocols and serious configuration overhead. While calculating TE-aware shortest paths. the destination-based forwarding constraint at a node should be satisfied, because an IP router will forward a packet to the next-hop toward the destination by looking up the destination prefix. In this paper, we present a problem formulation of finding a set of TE-aware shortest paths in ILP, and propose a simple heuristic for the problem. From the simulation results, it is shown that TE-aware shortest path routing performs better than default shortest path routing and ECMP in terms of the maximum link load with the marginal configuration overhead of changing the next-hops.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.12B
• /
• pp.790-799
• /
• 2007

In this paper, we propose WLAN CR coexistence beacon protocol for thenext WLAN network. This method can provide WLAN with high-speed data rate in new WLAN architecture and network platform based on cognitive radio technology. WLAN CR devices that enter the CR network can know UHF channels by listening CR beacon including the coexistence parameter set and start using CR channel fast. During handover of WLAN device in UHF spectrums, WLAN device that lost their channel can change available channel by obtaining the current CR channel information from the CR beacon. In advance relaying coexistence parameter set to entire CR system, WLAN CR system can prepare own candidate channel set that is different with other CR system. In CR beacon and relay delay, we show the results that WLAN CR coexistence beacon protocol supports spectrum handover efficiently and decreases the probability of collision in candidate channel set.

• Information and Communications Magazine
• /
• v.28 no.4
• /
• pp.41-50
• /
• 2011

미래 전에서는 정보의 중요성이 더욱 부각되고 있으며 정보의 수집 및 전파, 정확한 지휘결심 및 전파, 기동타격체계의 통제 등으로 이어지는 지휘통제의 전 과정을 유기적으로 연결하여, 그 성능을 극대화시키는 것이 네트워크 중심전(NCW: Net-Centric Warfare)의 개념이다. NCW 실현을 위해 개발중인 여러 체계 중 주목 받고 있는 것이 무인기(UAV: Unmanned Aerial Vehicle) 이다. 무인기는 감시정찰, 고정밀 타격, 그리고 전투피해평가 기능 등을 수행하며, 전술적인 상황인식이 가능하게 한다. 무인기가 이러한 임무를 수행하기 위해서는 비행체의 상태정보, 비행체의 조종통제정보, 그리고 임무 탑재체가 획득한 정보의 간단없고 정확한 전달이 요구된다. 이러한 정보를 전송하기 위한 비행체와 지상체간의 제반 통신을 데이터 링크(Data Link)라 하며, NCW 구현에 있어서 가장 핵심이 되는 요소이다. 세계 각국은 영상정보 수집자산으로서 무인기와 데이터링크의 개발에 박차를 가하고 있는 실정이며, 우리 군도 전력화가 계획된 각 제대별 무인기의 통합운용을 위한 영상정보 공용데이터 링크 (MPI-CDL: Multi-Platform Image and Intelligence Commom Data Link)를 개발중에 있으며 지속적인 영상정보 수집자산의 소요증가에 따른 주파수 획득문제와 사업별 독자적인 데이터 링크의 개발을 지양하고 기존체계와의 상호운용 및 단절없는 통신을 보장을 위해 개발과 동시에 국가적 차원에서의 기술구조 표준화가 추진되어야 한다. 이러한 시점에서 본고에서는 먼저 선진국의 (CDL : Commom Data Link) 표준화 동향을 알아보고, 상호운용성과 연동을 위한 한국형 MPI-CDL 기술 표준화방향을 제시하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.47 no.5
• /
• pp.74-80
• /
• 2010

Speech and audio codecs have been developed based on different type of coding technologies since they have different characteristics of signal and applications. In harmony with a convergence between broadcasting and telecommunication system, international organizations for standardization such as 3GPP and ISO/IEC MPEG have tried to compress and transmit multimedia signals using unified codecs. MPEG recently initiated an activity to standardize the USAC (Unified speech and audio coding). However, USAC RM (Reference model) software has been problematic since it has a complex hierarchy, many useless source codes and poor quality of the encoder. To solve these problems, this paper introduces a new RM software designed with an open source paradigm. It was presented at the MPEG meeting in April, 2010 and the source code was released in June.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.16 no.4
• /
• pp.430-435
• /
• 2006

In this paper, we propose a method based on multimodal biometrics system using the face and signature under ubiquitous computing environments. First, the face and signature images are obtained by PDA and then these images with user ID and name are transmitted via WLAN(Wireless LAN) to the server and finally the PDA receives verification result from the server. The multimodal biometrics recognition system consists of two parts. In client part located in PDA, user interface program executes the user registration and verification process. The server consisting of the PCA and LDA algorithm shows excellent face recognition performance and the signature recognition method based on the Kernel PCA and LDA algorithm for signature image projected to vertical and horizontal axes by grid partition method. The proposed algorithm is evaluated with several face and signature images and shows better recognition and verification results than previous unimodal biometrics recognition techniques.

• Journal of IKEEE
• /
• v.13 no.3
• /
• pp.62-71
• /
• 2009

In this study, we developed a wireless CROS(contralateral routing of signal) hearing aid for unilateral impaired people. CROS hearing aid takes sound from an ear with poorer hearing and transmit to another ear with better hearing. Generally, the self-voice delivered through the receiver of CROS hearing aid can be very loud. It is hard to perceive target speech because of loud self-voice. To compensate it, a self-voice suppression algorithm has been developed. we performed SDT(speech discrimination test) for evaluation of the self-voice suppression algorithm. One-syllable words was used as test speech and recorded with self-voice at a 1m distance. As the results, SDT score was improved about 11% when the self-voice suppression algorithm was processed. It is verified that the self-voice suppression algorithm helps speech perception at a time to communicate with others.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.11
• /
• pp.125-133
• /
• 2010

A policy based resource management framework is proposed, that supports the optimal QoS by applying resources management function which is changed according to the status of mobile terminal and heterogeneous connections to hand-over process of mobile terminals based on heterogeneous network. To assess the performance of policy based resource management framework proposed in this thesis, in case of applying weighted policy for selecting optimal cell in hand-over occurring among duplicated heterogeneous connections, the transmission delay was remarkably enhanced as the number of multimedia sessions increased. This means, in case of QoS deterioration of multimedia session occurring in service connection, hand-over was executed with the optimal connection.