• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.169-172
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• 2000

We have constructed a multi-channel SQUID magnetometer system. The system is designed to operate normally with 10 high temperature direct coupled SQUIDs. The main features of the system include a remote control by serial communication, low noise with wide bandwidth and high slew rate by several MHz modulation, signal conditioning and calibration by digital signal processing.

• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.630-634
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• 2010

In this paper, we designed and fabricated a multi-band folded monopole antenna for mobile handsets that can be used for multiple services. The proposed antenna, with a small size of $28.060{\times}12.665{\times}5.035mm^3$ can provide sufficient bandwidth to cover the GSM900 (Global System for Mobile Communications: 880-960 MHz), DCS (Digital Cellular System: 1710-1880 MHz), K-PCS (Korea-Personal Communication Service: 1750-1870 MHz), Wibro (2300-2390 MHz) and Bluetooth (2400-2483 MHz) bands.

• 전자공학회논문지A
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• 제32A권2호
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• pp.120-129
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• 1995

A new nethod, namely multi-gain-levering, is proposed to improve FM response of the single frequency semiconductor lasers and applied to 1.55$\mu\textrm{m}$ InGaAsP/InP MGL(multi-gain-levered)-MQW-DFB-LD. This device consists of three sections with different bandgap energy and can be easily realized by selective MOVPE growth. Our analysis based on Green function showed that a flat, red-shifted, high FM efficiency of aove 15GHz/mA can be extected by novel gain-levering scheme.

• 한국전자통신학회논문지
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• 제4권1호
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• pp.33-36
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• 2009

Incremental converters provide a solution for such measurement applications, as they retain most of the advantages of conventional ${\Delta}{\Sigma}$ converters, and yet they are capable of offset-free and accurate conversion. Most of the previous research on incremental converters was for single-channel and dc signal applications, where they can perform extremely accurate data conversion with more than 20-bit resolution. In this paper, a design technique for implementing multi-channel incremental data converters to convert narrow bandwidth ac signals is discussed. It incorporates the operation principle, topology, and digital decimation filter design. The theoretical results are verified by simulation results.

• 융합보안논문지
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• 제8권2호
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• pp.95-102
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• 2008

본 논문에서는 simple node 토폴로지의 망 정보를 효율적으로 요약함으로써 망에서의 호 성공률, 액세스 타임을 향상시켜 망의 전체적인 QoS를 향상시키기 위한 토폴로지 요약 기법을 제안하였다. 제안된 기법에서는 대역폭과 지연 파라미터를 중심으로 라인 세그먼트를 이용하여 경계노드 사이의 다중 경로 정보를 요약함으로써 토폴로지 요약 정보를 줄이고 다중링크 요약에 유연성을 부여하여 망의 성능을 향상시킬 수 있었다. 제안된 기법의 성능을 평가하기 위해 기존의 simple node 토폴로지 요약 기법과 호 성공률, 접근시간에 대하여 컴퓨터 시뮬레이션을 통해 비교 분석하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.131-134
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• 2004

The object of this study is to design the Radar Absorbing Structures (RAS) having sandwich structures in the X-band $(8.2\~12.4GHz)$ frequencies. Glass fabric/epoxy composites containing conductive carbon blacks and carbon fabric/epoxy composites were used for the face sheets. Polyurethane (PU) foams containing multi­walled carbon nanotube (MWNT) were used for the core. Their permittivities in the X-band were measured using the transmission line technique. The reflection loss characteristics for multi-layered sandwich structures were calculated using the theory of transmission and reflection in a multi-layered medium. Three kinds of specimens were fabricated and their reflection losses in the X-band were measured using the free space technique. Experimental results were in good agreements with simulated ones in 10dB absorbing bandwidth.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권4호
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• pp.1249-1265
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• 2022

Video streaming has become one of the most popular applications for mobile devices. The network bandwidth required for video streaming continues to exponentially increase as video quality increases and the user base grows. Multi-Path TCP (MPTCP), which allows devices to communicate simultaneously through multiple network interfaces, is one of the solutions for providing robust and reliable streaming of such high-definition video. However, mobile video streaming over MPTCP raises new concerns, e.g., power consumption and cellular data usage, since mobile device resources are constrained, and users prefer to minimize such costs. In this work, we propose a mobile video streaming framework over MPTCP (mDASH) to reduce the costs of energy and cellular data usage while preserving feasible streaming quality. Our evaluation results show that by utilizing knowledge about video behavior, mDASH can reduce energy consumption by up to around 20%, and cellular usage by 15% points, with minimal quality degradation.

• 전자통신동향분석
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• 제37권4호
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• pp.46-59
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• 2022

The 5G MEC (Multi-access Edge Computing) technology offers network and computing functionalities that allow application services to improve in terms of network delay, bandwidth, and security, by locating the application servers closer to the users at the edge nodes within the 5G network. To offer its interoperability within various networks and user equipment, standardization of the 5G MEC technology has been advanced in ETSI, 3GPP, and ITU-T, primarily for the MEC platform, transport support, and MEC federation. This article offers a brief review of the standardization activities for 5G MEC technology and the details about the system architecture and functionalities developed accordingly.

• 한국전자파학회논문지
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• 제20권7호
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• pp.664-672
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• 2009

본 논문에서는 다중 선로를 로딩시킨 새로운 구조의 글래스 안테나를 설계하였다. 제안된 안테나는 광대역 주파수 특성을 얻기 위하여 중심 선로에 다중 선로를 로딩하였으며, 수직 편파 복사 이득을 개선하기 위하여 이중 중심 선로 구조를 채택하였다. 세부적인 설계 변수는 Pareto 유전자 알고리즘을 이용하여 최적화하였으며, 이러한 설계 변수를 바탕으로 글래스 안테나를 실제 차량 유리에 인쇄한 후 측정하였다. 측정 결과, T-DMB 중심 주파수를 기준으로 49 %의 반전력 대역폭과 -3 dBi 이상의 전면 방향(bore- sight direction) 수직 편파 복사 이득, azimuth 방향에서 평균 -10 dBi 이상의 수직 편파 복사 이득을 보였다.

• 한국경영과학회지
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• 제41권2호
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• pp.53-65
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• 2016

Static wireless multi-hop networks, such as wireless mesh networks and wireless sensor networks have proliferated in recent years because of they are easy to deploy and have low installation cost. Two key measures are used to evaluate the performance of a multicast tree algorithm or protocol : end-to-end delay and the number of transmissions. End-to-end delay is the most important measure in terms of QoS because it affects the total throughput in wireless networks. Delay is similar to the hop count or path length from the source to each destination and is directly related to packet success ratio. In wireless networks, each node uses the air medium to transmit data, and thus, bandwidth consumption is related to the number of transmission nodes. A network has many transmitting nodes, which will cause many collisions and queues because of congestion. In this paper, we optimize two metrics through a guaranteed delay scheme. We provide an integer linear programming formulation to minimize the number of transmissions with a guaranteed hop count and preprocessing to solve the aforementioned problem. We extend this scheme not only with the guaranteed minimum hop count, but also with one or more guaranteed delay bounds to compromise two key metrics. We also provide an explanation of the proposed heuristic algorithm and show its performance and results.