• Clinical and Experimental Pediatrics
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• v.51 no.7
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• pp.771-774
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• 2008

Familial hypokalemic periodic paralysis (hypoPP) is a rare inherited channelopathy that often presents with episodic weakness accompanied by hypokalemia. Thus far, mutations in the gene encoding two ion channels (CACNL1A3, L-type calcium channel alpha-1 subunit and SCN4A, a sodium channel type IV alpha subunit) have been identified. Several cases of familial hypoPP in children have been reported in Koreans, but there are only a few cases with identified mutations. We report a 12-year-old boy and his affected mother with hypoPP who has a heterozygous G to A substitution at codon 1239 in exon 30 of the CACNL1A3 gene that causes a change from arginine to histidine (Arg1239His, CACNL1A3). This mutation is common among Caucasians; however, it has not yet been reported in Koreans. The patients were treated with oral acetazolamide and potassium replacement and were instructed to avoid precipitating factors. After the medication and lifestyle modification, the paralytic attacks significantly decreased.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.435-441
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• 2001

In this paper, we proposed adaptive MMSE receiver, which use channel equalizer to eliminate the interference due to multi-path fading and adaptive filter to eliminate the multiple access interference. The unique features of proposed receiver schemes are as following. We use pilot channel to estimate the channel coefficients exactly and guard symbols which are inserted periodically to estimate channel coefficients exactly without interference from user signals. The length of channel equalizer also can be reduced with the help of guard symbols. Especially utilizing adaptive code-matched filter(AMMSE) when the user population is high and SNR is not low we accepts excellent performance improvement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1A
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• pp.7-16
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• 2003

Handover is very important to support the mobility of user because wireless ATM networks have smaller cell size such as micro/pico cell for broadband mobile multimedia service In this paper, we propose dynamic path reservation handover scheme for fast inter-MSC (Mobile Switching Center) handovers To reduce the handover delay for connection re-routing, the proposed scheme reserves virtual channels from nearest common node to neighbor MSC in advance Especially, our handover scheme predicts the number of inter-MSC handover calls at each period by the prediction algorithm and reserve virtual channels The simulation and analysis results show that our scheme reduce handover complexity and has higher reservation channel utilization, compared with DVCT scheme.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.427-429
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• 2005

모바일 애드 흑 네트워크에서 않은 라우팅 프로토콜들이 연구되어지고 있다. 연구된 프로토콜 가운데 널리 쓰이고 있는 AODV는 On-Demand 방식으로써, 필요에 따라 라우팅 정보를 얻기 위한 메카니즘을 사용한다. 여기서 라우팅 정보를 얻은 이루에 링크 상태를 점검하기 위해서, Table-Driven 방식과 비슷하게 주기적으로 메시지를 전송함으로써 링크가 끊어질 경우의 상황을 인지 할 수 있도록 한다. 비록 On-Demand라 할지라도 주변에 노드들이 않으면, 라우팅의 유지를 위해 주기적으로 전송하는 패킷과 요구에 따른 라우팅 패킷으로 데이터를 전송하기 위한 대역폭에 영향물 줄 수 있다. 그래서 본 논문에서는 데이터를 전송하기 위한 채널과 제어/라우팅 정보를 교환하는 채널로 나누고 데이터를 전송하는데 있어서 신뢰성 있고 일정한 대역폭의 사용량을 줄 수 있는 방법을 제안한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.136-138
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• 2003

인기있는 비디오 스트림을 서비스하는 VOD시스템에서 다수의 사용자가 하나의 스트림을 공유할 수 있는 방법 중 하나로 주기적 브로드캐스팅 기법이 있다. 이 방법은 비디오 스트림을 주기적으로 브로드캐스팅해줌으로서 다수의 사용자에 대한 서버의 로드가 일정하게 유지되는 효과로 확장성(Scalability)을 갖지만 별도의 채널을 두지 않는 한 VCR 기능을 제공할 수 없고 서비스 응답 시간이 길게 된다. 본 논문에서는 기존의 방법에 On Demand 기능을 만족시키기 위해 프락시 기반 프리픽스 기술을 도입하고 VCR의 일부 기능을 구현할 수 있는 방법을 제안하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.11a
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• pp.18-19
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• 2013

본 논문에서는 시간영역에서 Golay 시퀀스를 이용한 주파수 분할 다중화(orthogonal frequency division multiplexing; OFDM) 시스템의 채널 추정 기법을 제안하였다. 두 개의 시퀀스를 하나의 쌍으로 Golay 시퀀스 쌍은 이상적인 비주기 자기상관 특성을 가지며, 다중경로 채널 환경에서 직교성이 유지되는 강인한 특성을 가진다. 이러한 Golay 시퀀스 기반의 시간영역 채널 추정 기법은 시면 채널에서의 시간동기에 용이하며, Golay 시퀀스의 이상적인 자기상관 특성으로 인하여 채널 추정 시 수신단의 복잡도를 낮출 수 있는 장점을 갖는다. 그리고 OFDM 기반 시스템에서의 PAPR(peak to average power ration) 문제를 해결할 수 있다. 그러므로 본 논문에서는 Golay 시퀀스의 특성을 이용한 전송 구조 제안 및 채널 추정 성능을 시뮬레이션을 통하여 분석하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.4
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• pp.335-341
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• 2015

In this study, we analyzed a two-dimensional Stokes flow through a microchannel containing projections with constant spacing attached to each wall. The projections on the top and bottom walls were semi-circular in shape, with in-phase locations. By considering the periodicity and symmetry of the flow, the eigenfunction expansion and least squared error method were applied to determine the stream function and pressure distribution. For some typical radius and spacing values, the streamline patterns and pressure distributions in the flow field are shown, and the shear stress distributions on the boundary walls are plotted. In addition, the average pressure gradients in the microchannel are also calculated and shown with the radius and spacing of the projections. In particular, the results for the case of extremely small gaps between the projections on the top and bottom walls are in good agreement with the lubrication results.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.50-54
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• 2010

A Container Security Device (CSD) which is different existing RFID Tag strengthens the physical security as mounted inside the container and the information security as encrypts doubly a data. CSD must use the resources efficiently in order to operate with the battery. Therefore, it needs low-power mechanism which repeats the sleep period and channel scan period. However, by adjusting these periods, the trade-off occurs between energy efficiency and network connectivity. In this paper, we implement low-power CSD and resolve this problem by adjusting beacon period and channel scan time. As a result, We guarantee the network connectivity 95% or more and maximum life up to 16 days using common AA batteries.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.726-735
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• 2009

In this paper, we proposed a novel conditional access system to reduce the overhead transmission rate for messages which verify the entitlement of subscribers in bandwidth-limited system. We adapted a key update system with the tree structure which had been used for IP multicast to a group hierarchy for the subscriber groups or channel groups. We also analyzed the overhead transmission rate for periodic key update and aperiodic one for change in a subscriber. The numerical evaluations show that the proposed system can significantly reduce the overhead transmission rate for dynamic subscriber change up to several hundred thousands times for various system configuration.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.188-194
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• 2014

The feature extraction mechanism of the CASA(Computational Auditory Scene Analysis) system uses time continuity and frequency channel similarity to compose a correlogram of auditory elements. In segmentation, we compose a binary mask by using cross-correlation function, mask 1(speech) has the same periodicity and synchronization. However, when there is delay between autocorrelation signals with the same periodicity, it is determined as a speech, which is considered to be a drawback. In this paper, we proposed an algorithm to improve discrimination of channel similarity using Weighted Cross-correlation in segmentation. We conducted experiments to evaluate the speech segregation performance of the CASA system in background noise(siren, machine, white, car, crowd) environments by changing SNR 5dB and 0dB. In this paper, we compared the proposed algorithm to the conventional algorithm. The performance of the proposed algorithm has been improved as following: improvement of 2.75dB at SNR 5dB and 4.84dB at SNR 0dB for background noise environment.