• Journal of the Optical Society of Korea
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• 제13권2호
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• pp.234-239
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• 2009

This paper presents a theoretical and experimental investigation of the transmission and sensing characteristics of the biconically tapered cladded multimode fibers. The beam propagation method was used to examine the transmission characteristics with various structural parameters. The results show that the transmission of the biconically tapered cladded multimode fibers is sensitive to the mode of the input optical beam and the refractive index of the external medium. A refractive index sensor for the external medium was proposed based on the theoretical analysis, and its feasibility was demonstrated experimentally.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1887-1889
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• 1997

This paper reports the principle, design, configuration, and test results of the fiber optic security system using multimode fiber. In this system, optical fiber works as a sensing element. The length of sensing element may be from several meters to several killometers. Physical principle of this system is the dependence of interferometric pattern on the end of the fiber on mechanical perturbation in the area, where this fiber is situated. Near and far field patterns of the output light for multimode fiber are speckle pattern. A number of speckles on the fiber depends on mode numbers. Light intensity in each point of the fiber end depends on phase difference of modes. Finally we introduced a "Fiber Optic Security System based on Multimode" Fiber which we developed, it may be available in the field of the important area and building.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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• pp.468-473
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• 1998

An intelligent multimode target tracking algorithm using fuzzy logic is presented. Multimode tracking represents a synergistic approach that utilizes a variety of tracking techniques(centroid, correlation, etc.) to overcome the limitations inherent in any single-mode tracker. The design challenge for this type of multimode tracker is the data fusion algorithm. designs for this algorithm are based on heuristic rather than analytical approaches. A correlation-tracking algorithm seeks to align the incoming target image with a reference in age of the target, but has a critical problem, so called drift phenomenon. In this paper we will suggest a robust correlation tracker with gradient preprocessor combined by centroid algorithm to overcome the drift problem.

• 전기전자학회논문지
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• 제24권2호
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• pp.409-418
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• 2020

본 논문에서는 Si/SiO₂/Si₃N₄/SiO₂ 적층 구조를 갖는 Si₃N₄ 립-광도파로 기반의 다중모드 간섭기를 활용하는 집적광학 소산파 바이오센서에 대해서 서술하였다. 다중모드 간섭기의 이론적 배경에 대해서 검토하였고, 전산해석을 통해서 다중모드 간섭기 구조와 설계과정을 제시하였다. 다중모드 간섭기의 제원 (길이, 폭)이 소자 성능에 어떻게 영향을 미치는지 분석하였다. 분석물질의 굴절률 변화가 다중모드 간섭기의 모드 패턴형성 위치와 출력 광파워에 많은 영향을 미치고 있음을 확인하였고, 이 특성을 적용할 경우 집적광학 바이오센서로 활용 가능함을 입증하였다.

• 한국광학회지
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• 제33권6호
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• pp.252-259
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• 2022

투과 매트릭스 방법을 이용하여 다중모드 광섬유 출력단에서 빛의 세기 분포를 제어하는 연구를 수행하였다. 공간 빛 변조기를 이용하여 원형으로 배치된 Hadamard 고유모드 위상분포를 실험적으로 구현하고, 네 가지 위상 값 변조 방법을 통하여 다중모드 광섬유의 투과 매트릭스를 실험적으로 도출하였다. 도출한 투과 매트릭스를 기반으로 광섬유에 입사하는 빛에 공간적인 위상 분포를 사전에 적용함으로써 광섬유 출력단의 원하는 위치에 빛을 집속하고자 하였다. 다중모드 광섬유 출력단 코어의 특정 위치에서 주변 배경 신호 대비 최대 359.6배 큰 세기로 빛을 집속할 수 있었으며 다중모드 광섬유 코어 영역 전반에 걸쳐 평균적으로 104.6배 향상된 값으로 빛을 집속할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.845-846
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• 2012

• Asian Journal for Public Opinion Research
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• 제4권2호
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• pp.73-87
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• 2017

The Korean Academic Multimode Open Survey (KAMOS) is a national survey first conducted in 2016. Stratified cluster random sampling was used in an initial face-to-face survey during which panel members were recruited. The second survey allowed invited panel members to answer online or by phone. KAMOS includes both longitudinal items and omnibus items, i.e., researchers can propose questions to include on KAMOS. This paper seeks to establish that KAMOS is representative of the South Korean adult population. The demographic variables from the first survey were comparable to demographic variables from two well-respected surveys in South Korea: the KOSTAT Social Survey and the Gallup Korea Omnibus Survey. To ensure that there was no substantial difference between those who answered the first survey and those who answered the second survey, we compared the results of 22 items from the first survey. The 2,000 panel members who were invited to participate in the second survey had similar responses to the 1,008 of those who responded to the second survey. Based on our findings, KAMOS can be considered a representative sample.

• Wind and Structures
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• 제27권5호
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• pp.293-309
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• 2018

The prediction of multimode flutter relies, to a larger extent than bimodal flutter, on accurate modeling of the self-excited forces since it is challenging to perform experimental validation by using aeroelastic tests for a multimode case. This paper sheds some light on the accuracy of predicted self-excited forces by comparing numerical predictions of self-excited forces with measured forces from wind tunnel tests considering the flutter vibration mode. The critical velocity and the corresponding flutter vibration mode of the Hardanger Bridge are first determined using the classical multimode approach. Then, a section model of the bridge is forced to undergo a motion corresponding to the flutter vibration mode at selected points along the bridge, during which the forces that act upon it are measured. The measured self-excited forces are compared with numerical predictions to assess the uncertainty involved in the modeling. The self-excited lift and pitching moment are captured in an excellent manner by the aerodynamic derivatives. The self-excited drag force is, on the other hand, not well represented since second-order effects dominate. However, the self-excited drag force is very small for the cross-section considered, making its influence on the critical velocity marginal. The self-excited drag force can, however, be of higher importance for other cross-sections.

• 한국정보통신학회논문지
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• 제12권3호
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• pp.563-568
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• 2008

M개의 다중모드 평면 도파로와 N개의 홀로그램 필터를 이용하여 M개의 입력단자와 N개의 출력단자 사이에 광신호 교환을 수행할 수 있는 방법을 제안한다. 열광학 폴리머로 제작된 다중모드 평면 도파로는 광신호 교환을 위한 광신호 경로를 제공하고, 전기적 신호로 출력 스페클 패턴을 변화시킨다. 다중모드 평면 도파로로부터 발생한 스페클 패턴들은 연결 목적지를 결정하는 목적코드로 이용되며, 공간다중화 된 홀로그램 필터에 의해 출력단자로 연결된다. 제안한 시스템에 대해 광신호 교환이 가능함을 실험적으로 보였다.

• Journal of Power Electronics
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• 제19권1호
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• pp.201-210
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• 2019

This paper proposes a multimode hybrid control strategy that can achieve zero-voltage switching of primary switches and zero-current switching of secondary rectifier diodes in a wide input voltage range for full-bridge LLC resonant converters. When the input voltage is lower than the rated voltage, the converter operates in Mode 1 through the variable-frequency control strategy. When the input voltage is higher than the rated voltage, the converter operates in Mode 2 through the VF and phase-shift control strategy until the switching frequency reaches the upper limit. Then, the converter operates in Mode 3 through the constant-frequency and phase-shift control strategy. The secondary-side diode current will operate in the discontinuous current mode in Modes 1 and 3, whereas it will operate in the boundary current mode in Mode 2. The current RMS value and conduction loss can be reduced in Mode 2. A detailed theoretical analysis of the operation principle, the voltage gain characteristics, and the realization method is presented in this paper. Finally, a 500 W prototype with 100-200 V input voltage and 40 V output voltage is built to verify the feasibility of the multimode hybrid control strategy.