• 한국통신학회논문지
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• 제11권3호
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• pp.217-226
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• 1986

DQSM알고리즘을 이용하여 다중채널 FIR디지털 필터를 구성하기 위한 한 기법을 제안하였다. 본 논문에서는 Double precision 알고리즘과 절대치회로를 이용하여 ROM용량을 감소시키고 절대치회로의 논리레벨의 단계를 줄이므로 동작속도를 개선할 수 있었다. 위의 기법으로 구성된 4채널 FIR디지탈필터의 주파수응답은 Remez exchange 알고리즘으로 시뮬레이션하여 얻어진 주파수응답과 잘 일치하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.542-545
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• 2008

Experiments have been performed to investigate effects of pulsating cathode flow on a 10-cell proton exchange membrane fuel cell (PEMFC) stack. For all the experiments, the flow rate, temperature and relative humidity of hydrogen at the anode inlet are fixed. The effects of the pulsating frequency, amplitude and flow rate at the cathode inlet on performance of 10-cell PEMFC are examined. The polarization and power curves show that the power output and limiting current is substantially increased when the pulsating component is added to cathode flow channel. The maximum power output increases by up to 38% and enhancement of the overall performance is more pronounced at lower flow rate region.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2098-2117
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• 2012

This paper jointly investigates the bandwidth allocation, transmission strategy and relay positions for two-way transmission aware cellular networks with network coding (NC). Our goal is to minimize the transmission power of mobile terminals (MTs). Consider a cellular system, where multiple MTs exchange information with their common base station, firstly, we propose an efficient bandwidth allocation method and then give a transmission strategy for each MT to determine whether to use relay stations (RSs) for its two-way transmission with the BS or not. To further improve the system performance, the optimal positions of RSs are also jointly discussed. A GA-based algorithm is presented to obtain the optimum positions for RSs. Besides, the impacts of frequency reuse on MT's transmission power and system spectral efficiency (SE) under different number of relays are also discussed in our work. Numerical results show that the proposed NC aware scheme can extend MTs' battery life at least 6% more than traditional method.

• Journal of Computing Science and Engineering
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• 제2권4호
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• pp.412-427
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• 2008

We propose ID-exchange protocol for Connectionless Location-Awareness Service (CLAS) to locate mobile nodes in indoor sensor network. When adapting location-awareness service to sensor network, the target system must be designed in accordance with various metrics which reflect the system requirement. We especially consider sustainability of the existing service which has been provided for its original purpose, such as environmental monitoring. The detailed meaning of sustainability here is that, even if location-awareness service is newly added to the existing service, the system must be assured to retain a stable network condition, and to deal with newly caused traffic properly. The CLAS ID-exchange protocol is especially designed for fixture and mobile nodes communication to achieve these properties. The protocol operates on 802.15.4 MAC layer to make mobile node work independently of the procedure to build routing table of fixture node, so a stable routing condition can be achieved even if there are many mobile nodes. Moreover, the dedicated frequency channel is assigned only for this protocol, so that traffic caused by location-awareness service can be distributed to another channel. A real system adapting the protocol was implemented to monitor fire and authorities' positions. We verified the overhead and elapsed time for location-awareness. The result shows the proposed protocol has a high performance in detecting speed, traffic distribution, and stability of overall network.

• 대한의용생체공학회:의공학회지
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• 제36권6호
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• pp.241-250
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• 2015

Noninvasive temperature monitoring is feasible with Magnetic Resonance Imaging (MRI) based on temperature sensitive MR parameters such as $T_1$ and $T_2$ relaxation times, Proton Resonance Frequency shift (PRFs), diffusion, exchange process, magnetization transfer contrast, chemical exchange saturation transfer, etc. While the temperature monitoring is very useful to guide the thermal treatment such as RF hyperthermia or thermal ablation, the optimization of the MR thermometry method is essential because the range of temperature measurement depends on the choice of the measurement methods. Useful temperature range depends on the purpose of treatment methods, for example, $42^{\circ}C$ to $45^{\circ}C$ for RF hyperthermia and over $50^{\circ}C$ for thermal ablation. In this paper, MR thermometry methods using $T_1$ and $T_2$ relaxation times and PRFs-based MR thermometry are tried on a 3.0 T MRI system and their results are reported and compared. In addition, the scanning protocol and temperature calculation algorithms from $T_1$ and $T_2$ relaxation times and PRFs are optimized for the different temperature ranges for the purpose of RF hyperthermia and/or thermal ablation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.511-514
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• 2003

The human being uses speech signals to exchange information. When background noise is present, speech recognizers experience performance degradations. Speech recognition through speech enhancement in the noisy environment was studied. Histogram method as a reliable noise estimation approach for spectral subtraction was introduced using MFCC method. The experiment results show the effectiveness of the proposed algorithm.

• 한국정보통신학회논문지
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• 제15권6호
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• pp.1245-1250
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• 2011

본 연구에서는 RFID(Radio Frequency Identification)와 HL7(Health Level 7) 프로토콜을 이용하여 병원을 내원한 환자의 접수를 보다 신속하고 효율적으로 처리할 수 있는 시스템을 설계하였다. 본 논문에서 설계한 시스템을 사용하면 접수뿐만 아니라 병원 내에서의 환자 정보의 활용이 가능하며 이는 병원 내에서 중복적인 서류 처리나 환자 정보를 얻기 위한 과정을 축소시킬 수 있다. 또한 HL7 프로토콜을 이용하여 병원 진료 과정을 고려한 HL7 메시지 구조를 설계하고 적용하였다. 본 논문에서는 서비스 로봇을 이용하여 환자 접수 기능을 구현하였으며, 향후과제로 진료 시에 필요한 혈압 및 체온 등 생체 데이터를 로봇을 이용하여 취득할 수 있는 기능을 추가 하는 것이다.

• 한국정보통신학회논문지
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• 제21권12호
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• pp.2249-2260
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• 2017

해상통신은 국제해사기구(International Maritime Organization, IMO)에서 세계 해상 조난 및 안전제도(Global Maritime Distress and Safety System, GMDSS)를 마련하고, SOLAS 규약에 따라 조난 및 안전 시스템을 탑재하도록 의무화하고 있다. Digital-HF(High-Frequency) 해안국 통신 시스템은 선박과 해안기지국 사이에 상호 운용성을 유지하며, 기존 아날로그 기반의 음성통신을 디지털화하여 해상이동업무에서 디지털 데이터 교환을 하기 위한 시스템이다. 본 논문은 디지털 HF통신을 위해 ITU에서 제정한 ITU-R M.1798-1을 분석하고, 기존 Annex 2와 Annex4의 문제점을 개선하여 Advanced annex2와 새로운 부속서인 Annex 5를 제안하고자 한다. 제안된 OFDM 프로토콜은 기본적으로 정보 송신측(ISS)과 정보 수신측(IRS)간의 반이중화 방식으로 에러발생시 재전송을 하는 ARQ(Automatic Retransmission Request)방식을 취하고 있으며, 이에 상응하는 구현 및 성능향상에 관한 기술적 개발을 하여 기존에 제시된 ITU-R M.1798-1보다 안정성과 우수성을 확보한 디지털 HF 통신시스템을 제안하고자 한다.

• 통상정보연구
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• 제6권2호
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• pp.171-191
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• 2004

Recently, RFID(Radio Frequency IDentification) is observed with government and connection enterprises as the central figure. RFID utilizing radio is a technology that enable exchange of information sensing and recognize object. RFID is expected that the practical use limits widens by territory that can form vast market such as logistics management according to RFID's low-cost aggravation as well as usage of life and improvement of performance because present R&D is gone vigorously. Because RFID is possible application everywhere if it is various service industries as well as logistics, industry spot, manufactory and place that flowing of goods is, is used, and is becoming big limelight from society several territories.

• 한국통신학회논문지
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• 제40권7호
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• pp.1457-1467
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• 2015

해양 통신을 위한 VHF 대역 데이터 통신 시스템(VHF Data Exchange System: VDES)은 송수신단의 종류에 따라 서로 다른 주파수 대역을 사용하도록 설계되어 있으며, 육상국으로부터 멀리 떨어진 선박국에게 육상국과 연결성을 보장하기 위해 제안된 ASO-TDMA (Ad-hoc Self-Organizing TDMA) MAC 프로토콜을 이용하여 다중-홉 통신을 수행하는 경우에 주파수 채널간 부하 불균형 문제가 발생한다. 본 논문에서는 이러한 주파수 채널간 부하 불균형 문제를 해결하기 위해 통계적 기하(stochastic geometry) 모델링을 도입한다. 이를 기반으로 동일 홉 영역에서의 공간적 자원 재사용률을 분석하고, 각 홉 영역 별로 최적의 자원 할당을 통해 채널간의 부하 불균형 문제를 해결하여 자원 활용도를 극대화하는 것을 보인다.