• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.173-174
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• 2017

최근 태양광, Energy Storage System(ESS) 등의 신재생에너지의 발전과 직류기반의 디지털 기기가 늘어나면서 직류전력망에 대한 관심이 증가하고 있다. 이에 따라 DC-DC 컨버터의 필요성이 증가하고 있다. DC-DC 컨버터의 경우 동기식과 비동기식의 스위칭 방식을 고려할 수 있으며, 각 방식에 따라 전류가 다이오드 혹은 스위치를 통해 흐르게 된다. 본 논문에서는 동기 및 비동기 컨버터의 효율을 실제 실험을 통하여 비교 분석하였다.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2004년도 가을 학술발표논문집 Vol.31 No.2 (3)
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• pp.646-648
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• 2004

컴퓨터와 인터넷의 급속한 보급으로 인해 원격교육(Distance Learning)에 대한 많은 연구가 진행되고 있다. 그러나, 지금까지 대부분의 원격교육 시스템은 웹 기반의(Web-Based) 비동기(asynchronous) 형태로써 피교육자가 이미 제작된 컨텐츠를 다운로드하여 보는 단순한 형태의 교육방식이다. 따라서, 전통적인 면대면(Face-to-Face) 교육방식을 대체할수 있는 원격교육이 되기 위해서는 교육자와 피교육자, 피교육자와 피교육자간에 인지(awareness) 및 상호작용(interaction)이 가능한 원격교육의 기능이 지원되어야 한다. 본 논문에서는 비디오 및 오디오 컨퍼런싱(video and audio conferencing), 텍스트 기반 대화(text-based chat), 선 밀 텍스트 애노테이션이 가능한 슬라이드(slide with line and text annotation)를 제공하고 피교육자에 대한 인지정보(awareness information)를 공유하는 동기식 세미나용 원격교육 시스템을 설계하고 구현하였다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1996년도 추계학술대회발표논문집; 고려대학교, 서울; 26 Oct. 1996
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• pp.157-161
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• 1996

This paper presents a method for designing private networks considering response time under packet switching network environment Specifically, we propose the designing process of a private network, where the host is assumed to be synchronous and the terminals to be asynchronous, according to protocol and access lines. To calculate the response time for the networks, we use the mutual independent M/M/1 and M/W/s queueing models. Comparing the response time derived from the model with the actual one, it is found that the model yields almost same performance in a more economic way. From the experiment, it is suggested that the necessary number of lines as well as the response time for a specific network can be estimated properly by sensitivity analysis.

• 인터넷정보학회논문지
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• 제2권5호
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• pp.71-79
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• 2001

분산 데이터베이스에서 사본을 복제하는 것은 성능, 가용성, 자치성 향상을 위한 것이다. 그러나 일관성을 엄격하게 적용하는 것은 실제 시스템에서 매우 어렵다. 본 논문에서는 지연 갱신 전파로 일관성을 완화하고. 즉시 갱신 전파로 그룹 갱신을 허용하는 혼합 프로토콜을 제시한다. 이 프로토콜은 그룹 갱신의 일관성을 위하여 사본들의 버전번호를 관리하고, 지연 갱신 트랜잭션의 직렬성을 위하여 반순서화한 사본 스패닝 트리를 생성한다. 비동기 갱신과 동기 갱신 기법을 혼합하여 약한 일관성을 유지한다. 성능 분석에 관한 연구는 향후 연구로 한다.

• Journal of Power Electronics
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• 제14권6호
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• pp.1139-1146
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• 2014

Digital signal processor (DSP) and field programmable gate array (FPGA) based concentrated control systems are designed for implementing CPS-SPWM strategies. The self-defined universal asynchronous receiver/transmitter (UART) protocol is used for communication between a master controller and an individual module controller via high speed links. Aimed at undesired pulse competition, this paper analyzes its generation mechanism and presents a new method for eliminating competition pulses with no time delay. Finally, the proposed concentrated controller is applied to a 10kV/10MVar distribution static synchronous compensator (DSTATCOM) industrial prototype. Experimental results show the accuracy and reliability of the concentrated controller, and verify the superiority of the proposed elimination method for competition pulses.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.29-32
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• 2001

This paper has simulated the PER(Packet Error Rate), ratio of received packet and payload BER of Bluetooth system with packet types of ACL(Asynchronous Connection Less) and SCO(Synchronous Connection Oriented) link over wireless Ad-hoc environment. AWGN(Additive White Gaussian Noise) and Rayleigh fading are considered as channel model, and the analysis is based on the baseband model of Bluetooth system. In terms of PER and ratio of received packet, performance of DM1 packet is almost same as those of HV1, HV2 and HV3 packets, the performances of the other packets depend on the packet types. In terms of payload BER performance, there is no difference among HV2 packet of SCO link and DM1, DM3, DM5 packets of ACL link. Moreover, there is no difference among HV3 packet of SCO link and DM1, DM3, DM5 packets of ACL link, too.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.25-28
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• 2001

In this paper we implement moving picture transfer system using bluetooth Development Kit (DK). To reduce the size of the image data, we use M-JPEG compression. We use bluetooth Synchronous Connection-Oriented (SCO) link to transfer voice data. Server receive image data from camera and compress the image data in M-JPEG format, and then transmit the image data to client using bluetooth Asynchronous connection-less (ACL) link. Client receive image data from bluetooth ACL link and decode the compressed image and then display the image to screen. Sever and Client can transmit and receive voice data simultaneously using bluetooth SCO link. In this paper bluetooth HCI commands and events generated by host controller to return the results of HCI commands are explained and the flow of bluetooth connection procedure is presented.

• 한국인지과학회:학술대회논문집
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• 한국인지과학회 2010년도 춘계학술대회
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• pp.55-59
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• 2010

To examine iterocular interactions in normal subjects, we recorded EEG activity from channel O1 and O2 on 14 healthy subjects while checkerboard pattern reversals were presented to each eye with different interstimulus intervals (ISIs) ranging from 0 to 218 ms. When pattern reversals were presented asynchronously to each eye, P-1 activity evoked by each reversal was significantly suppressed compared to the activation evoked by synchronous reversals. Furthermore, when there was time delay between pattern reversals to each eye, theta (4-10 Hz) band power was also significantly decreased, whereas beta (10-30 Hz) band power was relatively preserved. Our results suggest that neural activity evoked by sustained but not yet reversed checkerboard from one eye might inhibit upcoming neural response evoked by reversed checkerboard from the other eye. Decreased P-1 activity might reflect such inhibitory interaction between two eyes. Also, decreased theta and preserved beta band power might reflect engagement of different neural circuit for binocular / monocular vision.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1992년도 추계학술대회
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• pp.127-129
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• 1992

In this paper, we describe about control system for eletro-hydraulic LVAD(Left Ventricular Assist Device) and control algorithm for two operation mode. One is asynchronous operation mode and the other is synchronous operation mode synchronized with natural heart's R pulse. We also present implementation method of software PI algorithm for velocity control of motor used in LVAD system and its response.

• Bulletin of the Korean Chemical Society
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• 제24권3호
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• pp.357-362
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• 2003

The pathway producing imide ring closure during the thermal imidization of poly(amic acid) (PAA) was investigated in detail using a new analytical method, two-dimensional (2D) Raman correlation spectroscopy. The signs of the cross peaks in synchronous spectra provided evidence of the thermal imidization of PAA into PI as the heating temperature increased. The signs of the cross peaks in asynchronous spectra suggested that the imide-related modes changed prior to the amide or carboxylic mode, which indicates that cyclization occurred before the amide proton was abstracted.