• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.465-467
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• 2010

This paper proposes MIMO two-way cooperative relay scheme to optimize the end to end capacity in wireless multi-hop mesh network. The basic idea is to perform data transmission via multi-hop relay nodes, in equidistant topology, this method is quite efficient. However, on one hand this topology is very rare in practical situation, on the other hand, in real practical situation where the topology is most likely non equidistant, the end to end capacity significantly degrades due to bottleneck link caused by uneven SNR. Moreover, the end to end capacity degrades at high SNR due to overreach interference from far nodes existing in multi-hop relay networks. In this paper, MIMO two-way cooperative relay in the region of non equidistant nodes is found efficient to improve the end to end capacity. The proposed scheme is validated using numerical simulation.

• 대한전자공학회논문지TC
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• 제41권6호
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• pp.25-31
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• 2004

IEEE 802.11 무선랜은 무선으로 근거리 단말들을 연결하는 통신 기술로, 높은 데이터 전송률을 제공할 수 있다. 무선랜은 보통 하나의 AP와 하나 이상의 단말 기기가 기본 서비스 영역을 이루며 이를 BSS라고 한다. AP에서 거리가 멀리 떨어진 단말은 신호의 세기가 약해지고 고속 데이터 전송률의 보장을 받을 수 없는 단점을 가지고 있다. 본 논문에서는 이런 단점을 개선하기 위해서 고속 데이터 전송이 가능하도록 무선 단말 중 일부를 중계 단말로 이용함으로써 그룹화를 통해 고속 데이터 전송을 가능하게 하는 방법을 제안하고, 시뮬레이션을 통해 제안한 무선 단말의 그룹화 알고리즘을 분석하였다. 그 결과 제안된 그룹화 알고리즘이 고속 데이터 전송을 위한 무선 단말을 위한 그룹화에 효과적인 방법임을 보였다.

• 한국산학기술학회논문지
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• 제10권11호
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• pp.3399-3404
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• 2009

RFID 시스템은 리더기가 물체에 부착된 태그의 정보를 무선으로 파악하는 장거리 인식용으로 사용되고 있다. 그렇지만, 각기 구현하는 방식에 조금의 차이가 있어 각 제품들 간의 호환이나, 태그와 리더기 사이의 호환이 원만히 이루어지지 않고 있는 것이 문제점이다. 따라서, 본 연구에서는 몇 가지 서로 다른 프로토콜을 탑재하여 다양한 종류의 태그와 리더기를 검사하고, 고주파 특성과 프로토콜을 동시에 검증할 수 있는 시스템을 설계 및 구현하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.162-164
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• 2006

There are concern on possible health effects from exposure to electric and magnetic fields. One reflection of this concern is the considerable controversy, delay, and cost increases involved in the construction of utility lines and facilities. To meet such challenges, in this paper we investigated magnetic fields reduction techniqies such as general compaction, in-span compaction, cruciform, vertical, 3way splits phase, and 4way splits phase. As results, we found 1 spacer in-span compaction was appropriate in Korea in view of effectiveness and economy.

• 한국시뮬레이션학회논문지
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• 제19권2호
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• pp.137-145
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• 2010

본 연구는 LBS(Location Based Service) 기반에 5.8-5.9Ghz RSU를 이용한 실시간 교통 시스템(RTS)에 관한 연구이다. 제안된 LBI(Location based Broadcast system on ITS)는 방송국 T-DMB 시스템과 ITS 기반 실시간 교통 시스템을 융합하고, 노변기지국(RSU:Road Side Unit)을 중심으로 제공되는 운전자를 위한 지역정보 기반 서비스이다. 본 방송국과 ITS의 융합은 IP기반 양방향 통신은 IP 기반으로 이루어지며, RSU를 이용하여 차량 위치의 파악을 통한 LBS(Location Based Service)를 제공한다. 지역 매크로 관리자(LMM)과 지역 방송국과 상호 정보 교환으로 정보 전달의 실시간성과 서비스의 다양성을 제공할 수 있었다. 기존 실시간 교통시스템에서 전송 범위(transmission area)의 한계와 기존 T-DMB의 단방향 서비스 문제를 상호 보완하였다. 이를 통해 개별 운전자의 실시간 양방향 서비스를 제공할 수 있었다. 또한 운전자들에게 실시간 교통 및 지역정보를 제공함으로써 분산효과와 서비스 확대를 제시하였다. 마지막으로 연구소 주변에 테스트 베드 구축과 구현으로 검증하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권12호
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• pp.5855-5877
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• 2017

In view of personal health and disease management based on cost effective healthcare services, there is a growing need for real-time monitoring services. The electrocardiogram (ECG) signal is one of the most important of health information and real-time monitoring of the ECG can provide an efficient way to cope with emergency situations, as well as assist in everyday health care. In this system, it is essential to continuously collect and transmit large amount of ECG data within a given time and provide maximum user convenience at the same time. When considering limited wireless capacity and unstable channel conditions, appropriate signal processing and transmission techniques such as compression are required. However, ISO/IEEE 11073 standards for interoperability between personal health devices cannot properly support compressed data transmission. Therefore, in the present study, the problems for handling compressed data are specified and new extended agent and manager are proposed to address the problems while maintaining compatibility with existing devices. Extended devices have two PM-stores enabling compression and a novel transmission scheme. A variety of compression techniques can be applied; in this paper, discrete cosine transformation (DCT) is used. And the priority of information after DCT compression enables new transmission techniques for performance improvement. The performance of the compressed signal and the original uncompressed signal transmitted over the noisy channel are compared in terms of percent root mean square difference (PRD) using our simulation results. Our transmission scheme shows a better performance and complies with 11073 standards.

• ETRI Journal
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• 제40권3호
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• pp.318-329
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• 2018

Femtocell (FC) technology envisaged as a cost-effective approach to attain better indoor coverage of mobile voice and data service. Deployment of FCs over macrocell forms a heterogeneous network. In urban areas, the key factor limits the successful deployment of FCs is inter-cell interference (ICI), which severely affects the performance of victim users. Autonomous FC transmission power setting is one straightforward way for coordinating ICI in the downlink. Application of intelligent control using soft computing techniques has not yet explored well for wireless networks. In this work, autonomous FC transmission power setting strategy using Adaptive Neuro Fuzzy Inference System is proposed. The main advantage of the proposed method is zero signaling overhead, reduced computational complexity and bare minimum delay in performing power setting of FC base station because only the periodic channel measurement reports fed back by the user equipment are needed. System level simulation results validate the effectiveness of the proposed method by providing much better throughput, even under high interference activation scenario and cell edge users can be prevented from going outage.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 춘계학술발표대회 논문집 제23권 1호
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• pp.235-239
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• 2004

Sound transmission either as airborne or structure borne is a potential problem that occurs in buildings either from sources within or from outside. With the expansion of real estate activities in countries like India, the need to attend sound insulation requirements also assumes greater dimensions. The focus of this research is on studying the sound transmission characteristics of building structures made of hollow blocks, neocrete block, aerocon block and prefabricated panels such as Ferrocement panel. The tests were carried out the blocks with and without plastering and their sound reduction index was measured at one-third octave frequencies. In the case of ferrocement panels, different types of systems were tested in the TL suite. Panels with cavity, with cavity ties, with insulation, with stiffeners and with plasterboard were investigated. Sound reduction index of these panels was measured with additional quantities like longitudinal wavespeed, and loss factors (internal and total loss factor). Tests were also conducted on Cypcrete wall panel and Sandwiched wooden panel in a similar way. Theoretical investigations were carried out using Statistical Energy Analysis (SEA) for the above systems. Sound reduction index was then compared between the predicted and the measured values.

• 한국인터넷방송통신학회논문지
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• 제12권6호
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• pp.43-48
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• 2012

무선랜과 스마트폰 등의 무선랜 기능을 내장한 단말기기가 활성화됨에 따라 무선 인터넷 지역 방송 서비스의 중요성이 커지고 있다. 이 경우 다수의 단말기에 방송 데이터를 전송하기 위해서는 단방향 방송기술이 사용되어야 하며, 데이터의 재전송이 불가하므로 방송 데이터의 수신 오류가 매우 커지는 문제가 있다. 또한 무선랜은 비허가 주파수를 사용하므로 타 무선기기에 의한 간섭으로 버스트 오류가 발생하는 속성이 있다. 본 논문에서는 버스트 오류와 랜덤 오류를 극복하기 위한 방법을 도입하고 그 효과를 분석하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1549-1554
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• 2000

HDD structure is excited by the dynamic motion of disk-spindle motor components. Those excitations which are generated at stator and magnet rotor, at bearings and from disk dynamics, are transmitted through motor spindle and flange to HDD cover and base. The operational deflection shape measurement can show the structural excitation patterns at the most influent frequency on the acoustic noise level. One of those components is the axial excitation along spindle, and the other is the local orbital excitation at contact area of motor flange and base. To make a reduction of those structural transmission excitations, the structure of spindle motor is modified to the direction of reinforcement at transmission path without change of bearings, magnet and coil. Some excitation of spindle motor component carrying out essential function is unavoidable. So it is the efficient way of HDD noise improvement to control the structural transmission of excitation.