• 한국광학회지
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• 제24권6호
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• pp.297-310
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• 2013

스마트 기기, 클라우드 서비스, 광가입자망 등의 보급에 따른 멀티미디어 기반의 대용량 인터넷 트래픽의 급속한 증가로 통신 수요는 연 40%이상씩 증가하고 있다. 이러한 대역폭 증가를 수용하기 위해서 광통신용 광부품의 진화도 각 계층별로 빠르게 진행되고 있다. 가입자망에서는 변조속도 증가와 더불어 파장다중방식의 도입이 시작되고 있고, 매트로망에서는 보다 효율적인 망 운용을 위해 차세대 ROADM에 대한 개발이 진행중이며, 장거리 통신에서는 코히어런트 통신 기반의 새로운 변조방식이 도입되어 스팩트럼 효율을 향상시키고 있다. 본 논문에서는 이러한 폭발적인 통신 대역폭 증가 요구에 따른 광통신망의 진화와 이를 수용하기 위한 고속화, 효율화, 저전력화로 발전하고 있는 핵심 광부품에 대해 살펴본다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.272-276
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• 1996

This study deals with the speed control of an overcentered variable-displacement hydraulic motor on a constant pressure network, which is noted for its high system efficiency fast dynamic response and energy recovery capability. The speed control characteristics of the conventional cascade PI controller are largely affected by load-torque disturbances. To obtain robust speed control despite torque disturbances, the load torque is estimated by an observer based on a mathematical model and compensated for by a feedforward loop. It is shown by experiment that robust speed control may be obtained with the proposed controller. The experimental data agree fairly well with the theoretical analysis.

• 한국철도학회논문집
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• 제9권1호
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• pp.36-42
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• 2006

Studied was a strategic plan for the Korean High-Speed Train system to penetrate the Chinese railway market in exchange of the technology of KHST. Firstly, taken was a glance at Chinese Government plans to extend total length of his railway lines and to construct the Beijing~Shanghai high-speed railway line. Then, disparity of railway technology in Korea and China was reviewed. From the review, SWOT Analysis were carried out to penetrate the foreign markets. Countermeasures to cope with SWOT were also considered. Strategical governmental supports and the establishment of the special organization to be in charge of penetration of KHST into foreign markets were proposed. Finally, also proposed was the transfer of KHST technology to Chinese counterparts in exchange of tangible benefits for Korean side. The benefits may include (1) adoption of KHST as the type of rolling stock for the Beijing~Shanghai line, (2) guarantee of participation in the project and royalty for the KHST technology used for the future high-speed railway line construction, (3) prior written approval and partnership when making its way to third country, and (4) participation of Korean construction companies in Chinese railway construction project, etc. Adoption of KHST in China indeed gives chance to integrate the high-speed railway network after reunification of Korean peninsular, and enhance the economic ties between two countries.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.907-914
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• 2005

Studied was a strategic plan for the Korean High-Speed Train system to penetrate the Chinese railway market in exchange of the technology of KHST. Firstly, taken was a glance at Chinese Government plans to extend total length of his railway lines and to construct the $Beijing\~Shanghai$ high-speed railway line. Then, disparity of railway technology in Korea and China was reviewed. From the review, SWOT Analysis were carried out to penetrate the foreign markets. Countermeasures to cope with SWOT were also considered. Strategical governmental supports and the establishment of the special organization to be charge of penetration of KHST into foreign markets were proposed. Finally, also proposed was the transfer of KHST technology to Chinese counterparts in exchange of tangible benefits for Korean side, The benefits may include (1) adoption of KHST as the type of rolling stock for the $Beijing\~Shanghai$ line, (2) guarantee of participation in the project and royalty for the KHST technology used for the future high-speed railway line construction. (3) prior written approval and partnership when making its way to third country, and (4) participation of Korean construction companies in Chinese railway construction project. etc. Adoption of KHST in China indeed gives chance to integrate the high-speed railway network after reunification of Korean peninsular, and enhance the economic ties between two countries.

• 융합보안논문지
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• 제8권1호
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• pp.9-18
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• 2008

고속으로 이동 중인 차량들 간의 긴급한 정보를 주고받아 고속도로에서의 다중충돌사고를 미연에 방지할 수 있는 차량 통신 프로토콜을 제안한다. 본 논문에서는, 도로위의 차량들은 서로 연계성이 없기 때문에 위치추적시스템인 GPS에서 수신한 거리 값을 연계하여 클러스터를 구성한다. 클러스터를 IEEE 802.11 MAC 계층에서 구성하기 때문에 경로 설정으로 인한 과부하문제를 해소 하였다. 논문에서 제안한 액티브 네트워크 기반의 멀티 홉 라우팅 프로토콜은, Active Network를 이용하여 안정된 통신이 이루어 질수 있도록 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권10호
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• pp.3608-3626
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• 2021

The detection of bolts is an important task in high-speed train inspection systems, and it is frequently performed to ensure the safety of trains. The difficulty of the vision-based bolt inspection system lies in small sample defect detection, which makes the end-to-end network ineffective. In this paper, the problem is resolved in two stages, which includes the detection network and cascaded classification networks. For small bolt detection, all bolts including defective bolts and normal bolts are put together for conducting annotation training, a new loss function and a new boundingbox selection based on the smallest axis-aligned convex set are proposed. These allow YOLOv3 network to obtain the accurate position and bounding box of the various bolts. The average precision has been greatly improved on PASCAL VOC, MS COCO and actual data set. After that, the Siamese network is employed for estimating the status of the bolts. Using the convolutional Siamese network, we are able to get strong results on few-shot classification. Extensive experiments and comparisons on actual data set show that the system outperforms state-of-the-art algorithms in bolt inspection.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2013년도 추계학술대회
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• pp.20-23
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• 2013

최근 방송사에서는 사용하는 고화질 제작용인 대용량 영상파일의 사이트간 전송을 위해 Public IP Network 을 많이 사용하고 있으나, 특히 장거리 Public IP Network 는 QoS 를 보장되지 않는 다양한 원인으로 인해서 전송성능이 저하가 심각하게 발생한다. 본 논문에서는 방송 디지털미디어의 대용량 HD 영상파일을 장거리 전송하는데 발생하는 성능 저하의 원인을 분석하고, 고속 파일전송을 위하여 Parallel TCP Application을 이용해서 다중세션으로 호스트간 Network 을 연결을 하는 방법을 통해서 Network 사용 효율성을 극대화하고 이용하는 구현 사례를 알아본다. 그리고 대용량 HD 영상파일의 고효율 고속 전송시스템을 방송사에서 사용한 결과를 실증하여 IP network 을 사용하는 효율적인 영상전송방식을 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.857-860
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• 1991

This paper describes a High-Speed 8-bit Current-Mode BiCMOS A/D Converter. The characteristics of this A/D Converter are as fellows. First, as ADC is operating in current-mode we can obtain the properties of increase of converting speed, low noise, and wideband. Second, the properties of high switching speed in bipolar transistor and of high packing density, low power consumption in MOS trnsistor are combined. Finally we reduce chip area by designing it with subranging mode and improve the converting speed by performing subtraction directly, which doesn't need D/A convertings, using current switching element. This converter is composed of two 4-bit ADC, current soure array which provides signal and reference current, current comparator and encoding network.

• 전자공학회논문지A
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• 제33A권2호
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• pp.50-58
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• 1996

This paper proposes the channel-access protocol suitable to a very high speed photonic WDM network with star configuration, which can provide a high channel utilization and insensitivity to the propagation delay. The proposed protocol employs a control channel and a simple status table to deal with the propagation delay which has been a major limiting factor in the performance of the very high speed optical communication networks. The control channel transmits control information in order to reserve access on data channels, and each node constitutes a status table after the reception of control pckets which holds information about the availbility of destination node and data channel. The proposed protocol is insensitive to the propagation delay time by removing necessity of the retransmission and by allowing parallel transmission of control packet and data packets. It is proved in analysis and discrete event simulation that the proposed protocol is superior in throughput and mean delay, especially at the high load conditions compared to the existing high speed channel-access protocols.

• 한국통신학회논문지
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• 제31권2B호
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• pp.91-97
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• 2006

네트워크 대역폭 증가에 따라 다양한 서비스의 등장과 함께 네트워크 위협이 꾸준히 증가하고 있다. 고성능 네트워크 보안의 실현을 위해, TCAM 등의 하드웨어를 통한 고속 네트워크에서의 빠른 패킷 분류 방법이 일반적으로 사용된다. 이러한 디바이스는 상대적으로 가격이 비싸고 용량이 충분치 않기 때문에 효율적으로 사용하기 위한 방법이 필요하다. 본 논문에서는 대표적인 침입탐지시스템인 Snort의 규칙집합을 이용하여 고속의 패킷 분류에 적합한 디바이스인 TCAM을 통한 효율적인 패킷 분류방법을 제안하였다. 제안한 방법에서는 값비싼 TCAM의 효율적인 사용을 위하여, TCAM을 분할함으로써 규칙상의 IP 주소와 포트의 중복 필드를 없애고 부정(negation), 범위(range) 규칙을 최소의 엔트리로 표현하도록 한다. 또한 포트번호 조합으로 TCAM 분할을 줄여 용량상의 이점은 유지하고, TCAM 검색횟수를 줄인다. 시뮬레이션을 통해 TCAM용량을 최대 98$\%$까지 줄이면서 대용량의 규칙을 사용하는 고속 패킷 분류에도 성능저하를 줄일 수 있음을 보인다.