• 한국통신학회논문지
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• 제10권6호
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• pp.296-307
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• 1985

다중모드와 단일모드 광섬유의 특성을 순회측정한 결가이다. 7개의 다중모드 광섬유와 4개의 단일모드 광섬유를 사용하여 5개의 국내 기관이 참여하고 비교, 연구하였다. 그 결과를 외국의 순회측정과 비교하여 보았다.

• 융합보안논문지
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• 제8권4호
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• pp.153-159
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• 2008

최근 GRIN 다중모드 광섬유는 광대역 통신선로로써 주목받아왔으며, 광섬유 내부에서 광파의 운동은 모드간 결합, 휨에 의한 손실 등 여러 다른 연구와 맞물려 큰 관심이 되고 있다. 본 논문에서는 기존의 복잡하고 난해한 Bessel 함수를 통한 파동방정식의 해석을 피하고 파동방정식을 고유치문제(Eigenvalue Problem)로 풀이한 수치해석을 통하여, GRIN 광섬유 내에서의 각 광파의 각 의존도와 모드수동을 관찰하였다. 이 연구는 GRIN 광섬유의 다른효과(휨, 모드간 결합) 등의 추후 연구에 유용하게 쓰이리라 생각된다.

• 제어로봇시스템학회논문지
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• 제16권2호
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• pp.177-187
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• 2010

A MTG (Multimode Tracking and Guidance) system is employed to compensate for the limitations of individual seekers such as RF (Radio frequency) or IIR (Imaging Infra-red) and to improve the overall tracking and guidance performance in jamming, clutter, and adverse weather environments. In the MTG system, tracking filter, data association, and data fusion methods are important elements to maximize the effectiveness of precision homing missile guidance. This paper proposes the formulation of a Kalman filter for the estimation of line-of-sight rate from seeker measurements in missiles guided by proportional navigation. Also, we suggest the HPDA (Highest Probability Data Association) and data fusion methods of the MTG system for target tracking in the adverse environments. Mont-Carlo simulation is employed to evaluate the overall tracking performance and guidance accuracy.

• Industrial Engineering and Management Systems
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• 제11권3호
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• pp.215-223
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• 2012

This paper focuses on three very similar evolutionary algorithms: genetic algorithm (GA), particle swarm optimization (PSO), and differential evolution (DE). While GA is more suitable for discrete optimization, PSO and DE are more natural for continuous optimization. The paper first gives a brief introduction to the three EA techniques to highlight the common computational procedures. The general observations on the similarities and differences among the three algorithms based on computational steps are discussed, contrasting the basic performances of algorithms. Summary of relevant literatures is given on job shop, flexible job shop, vehicle routing, location-allocation, and multimode resource constrained project scheduling problems.

• 한국분말재료학회지
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• 제10권4호
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• pp.249-254
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• 2003

WC-6wt%Co hard metal powders were sintered by a 2.45 GHz multimode microwave applicator in Ar atmosphere. Microwave sintering of WC-6wt%Co powder lowered the sintering temperature and shortened the processing time in less than two hours than by a conventional method. Microstructures of the sintered specimen were studied with scanning electron microscope (SEM) and no abnormal grain growth was observed. Mechanical properties were similar to the values of the specimens sintered by a conventional method. Specimen sintered at 135$0^{\circ}C$ for 30 minutes ,hewed 99%, 20.5 GPa and 8.1 MPa$\sqrt{m}$ of theoretical density, hardness and fracture strength, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1259-1261
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• 1993

Amorphous chalcogenide glasses are highly transparent in the near $1{\mu}m$ wavelength region, which corresponds to the wavelength region of the optical communication system. Optical properties of these materials, including the transmittance, the optical gap, and the shift associated with reversible photostruction change, were measured. Thereafter, optical waveguide was fabricated by the laser lithographic technique and then, guide modes were measured by utilizing the end-fire coupling technique. The field patterns of both the single mode and the multimode waveguide were observed.

• 대한원격탐사학회지
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• 제1권1호
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• pp.89-97
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• 1985

Hill-Sliding Clustering이라는 다변량 자료의 무감독 분류 방법을 Apple II personal computer의 BASIC언어를 사용한 Algorithm으로 개발하였다. 이 Algorithm으로 다변량 multimode를 갖는 정규 분포 자료에서 사전 지식없이 자료를 집단화하여 구분해 낼 수 있게 되 었다. 한국 연안 지역의 Landsat(지구 자원 탐사 위성)의 다중, Spectrum 영상 자료에 적용한 시 험 결과, 매우 고무적 결론을 얻었다.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.326-336
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• 2008

A WDM-PON has been considered as an ultimate solution for access networks. However, there were many technical and practical issues for commercial deployment. These issues were solved with wavelength locked F-P LD and the WDM-PONs employing this optical source were commercialized. These WDM-PON systems have been deployed in Korea, Europe, and US. We reviewed wavelength locking technology and WDM-PON achievements. When we inject spectrum sliced broadband light into an F-P LD, the multimode output is changed to a quasi single mode. Then, we can use the single mode light for WDM signal transmission. The broad spectral gain of the semiconductor gain medium enables a color-free operation of WDM-PON, i.e., an identical ONT can be used for each user. The wavelength locking properties depend on many parameters, especially alignment of injection wavelength to a lasing mode, passband profile of AWG and front facet reflectivity of F-P LD. However, these dependencies can be reduced by proper design of the laser and the injection bandwidth. Thus, WDM-PON systems have been achieved with color-free operation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권11호
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• pp.4611-4624
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• 2020

Future network scenario will be a heterogeneous wireless network environment composed of multiple networks and multimode terminals (MMT). Seamless switching and optimal connectivity for MMT among different networks and different services become extremely important. Here, a vertical handoff algorithm combined an improved entropy weighting method based on grey relational analysis (GRA) is proposed. In which, the improved entropy weight method is used to obtain the objective weights of the network attributes, and GRA is done to rank the candidate networks in order to choose the best network. Through simulation and comparing the results with other vertical handoff decision algorithms, the number of handoffs and reversal phenomenon are reduced with the proposed algorithm, which shows a better performance.

• 한국전자파학회논문지
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• 제29권1호
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• pp.36-41
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• 2018

본 논문에서는 밀리미터파(W 대역) 다중개구각 혼안테나를 제안하였다. 제안된 안테나는 전계면 및 자계면 빔폭이 동일한 다중모드 이중편파 정사각형 혼으로서 다중모드 생성부, 4개의 정사각형 도파관 여기부, 합패턴 형성을 위한 직교모드 변환기와 전력결합기로 구성된다. 제작이 용이하도록 안테나 구조를 설계하고, 층별 기계가공과 확산접합 기법을 적용하여 ${\pm}0.02mm$ 오차 이내로 제작하였다. 회로망분석기와 원전계 측정시설을 이용하여 제작된 안테나의 입력 반사계수와 방사패턴을 측정하였다. 측정 결과, 제안한 안테나는 중심 주파수를 기준으로 1 GHz 이내에서 17.7~18.3 dBi의 이득, $25.2{\sim}28.5^{\circ}$의 빔폭, 1.02~1.75의 입력 VSWR 특성을 가짐을 확인하였다.