• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.1-7
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• 2020

This study examines the processing and performance of an f-theta lens, one of the main components used in laser printer and laser scanning systems. To design an f-theta lens, the optical path of the components of the laser scanning unit f-theta lens, cylinder lens, and collimator lens must be identified. The goal after machining the master f-theta lens is to understand the optical properties, root mean square, and peak to valley.

• Smart Structures and Systems
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• v.11 no.2
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• pp.185-197
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• 2013

We developed a simultaneous strain measurement and damage detection technique using a pair of surface-mounted piezoelectric transducers and a fiber connecting them. This is a novel sensor configuration of the fiber acoustic wave (FAW) piezoelectric transducer. In this study, lead-zirconate-titanate (PZT) transducers are installed conventionally on a plate's surface, which is a technique used in many structural health monitoring studies. However, our PZTs are also connected with an optical fiber. A FAW and Lamb wave are simultaneously guided in the optical fiber and the structure, respectively. The dependency of the time-of-flight of the FAW on the applied strain is quantified for strain sensing. In our experimental results, the FAW exhibited excellent linear behavior and no hysteresis with respect to the change in strain. On the other hand, the well-known damage detection function of the surface-mounted PZT transducers was still available by monitoring the waveform change in the conventional Lamb wave ultrasonic path.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.49-54
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• 1986

In this paper we deal with a method of controlling PUMA 560 robot manipulator using a newly developed optical proximity sensor and the PDP-11/44 computer. The sensor output is different somewhat depending on an color of the object. The range of sensing vary from 38.4mm to 109.5mm for a real object, 39mm to 111.65mm for yellow, and 40.55mm to 107.25mm for blue. When an obstacle is encountered on the path of end-effector the system acknowledger immediatly the existence of the obstacle : and holds the motion of arm at a given distance. And also the system is capable of making the end effector avoid the obstacle automatically and keep on its motion.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.6
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• pp.78-83
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• 1999

This study discusses a non-contact optical technique, electronic speckle pattern interformetry(ESPI), that is well suited for in-plane and out-of-plane deformation measurement. However, the existing ESPI methods that are based on dual-exposure, real-time and time-average method have difficulties for accurate measurement of structure, due to irregular intensity and shake of phase. Therefore, phase shifting method has been proposed in order to solve this problem. About the method, the path of reference light in interferometry is shifted and added to least square fitting method to make the improvement in distinction and precision. This proposed method is applied to measure in -plane displacement that is compared with the previous method. Also, Used as specimen AS4/PE따 [30/=30/90]s was analyzed by ESPI based on real-time to determine the characteristics of vibration under no-load and tension. These results are quantitatively compared with those of FEM analysis inmode shapes.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.1
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• pp.1-15
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• 2005

In this paper, we deal with a mesh network design problem arising from the deployment of WDM for the optical internet. The mesh network consists of mesh topology for satisfying traffic demand while minimizing the cost of WDM, OXC, and fiber cables. The problem seeks to find an optimal routing of traffic demands in the network such that the total cost is minimized. We formulate the problem as a mixed-integer programming model and devise a tabu search heuristic procedure. Also we develop an optical internet design system that implements the proposed tabu search heuristic procedure. We demonstrate the computational efficacy of the proposed algorithm, compared with CPLEX 8.0.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.594-596
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• 2000

The best simulation condition for the fiber collimator that uses ball lenses was investigated. This kind of fiber collimator can be used in a Micro-Optical-Cross-Connects(MOXC). MOXC is composed of collimating ball lenses, micro mirrors and single-mode fibers. In order to design a MOXC, it is very important to calculate beam path, beam radius, divergence angle that determines the insertion loss of the MOXC. Since the beam profile from the fiber facet is not exact Gaussian profile, it was found that the simulation condition in which beam waist exists on the fiber facet, ignoring Numerical Aperture(NA), gives best agreement with the experimental results. Beam radii were measured with conventional knife edge method.

• Korean Journal of Optics and Photonics
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• v.27 no.1
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• pp.41-46
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• 2016

An optical method to measure the three-dimensional (3D) shape of a surface with specular reflection is proposed. The proposed method is based on the analysis of the geometric path of the light from a point source, and the relative displacements of points in the reflection image. The 3D shape of a concave mirror is shown to be determined approximately via experiments, where the vision system consists of LED array illumination, a half-mirror, and an imaging sensor.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.538-540
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• 2004

차세대 인터넷 어플리케이션으로서 각광받고 있는 다양한 실시간 멀티미디어 서비스들이 기존 인터넷망에서 유니케스트 라우팅 방식으로 제공되면서 사용자수의 한계와 서버의 부하 문제에 따른 여러 문제점을 안고 있다. 이로 인해 한번에 여러 사용자들에게 동일한 데이터를 보내야 하는 멀티미디어 서비스의 경우에는, 각 사용자들에게 데이터를 여러 번 전송하는 유니캐스트 라우팅(Unicaast Routing)방식에 비해 멀티캐스팅(Multicast Routing)방식으로 전송하는 것이 대역폭 활용면에서 더 효율적이다. 그러나 Multicast Routing 을 DWDM 기반의 차세대 광인터넷망에 적용하기에는 optical signal splitter의 사용으로 인한 cost의 증가와 Power Penalty 의 보상 문제 등 해결해야 할 여러가지 문제가 남아있다. 따라서 본 논문은 이러한 제한 사항을 극복하기 위해서 제한된 노드에 대해서만 optical signal splitter 를 사용하는 Virtual Source 기반의 Multicast Routing 알고리즘을 제안한다.

• ETRI Journal
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• v.24 no.2
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• pp.131-141
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• 2002

This paper considers a routing and wavelength assignment problem (RWAP) for the implementation of efficient Wavelength Division Multiplexing all-optical mesh networks without wavelength conversion. For a given physical network and required connections, the solution to the RWAP consists in how to select a suitable path and wavelength among the many possible choices for each connection so that no two paths using the same wavelength pass through the same link, while minimizing the number of required wavelengths. We introduce an integer programming formulation of the RWAP, which has an exponential number of variables, and propose an algorithm to solve it based on the column generation technique. The proposed algorithm can yield high quality solutions and tight lower bounds at the same time. Though the proposed algorithm cannot guarantee optimal solutions, computational results show that the algorithm yields provably good solutions within a reasonable time.

• ETRI Journal
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• v.37 no.6
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• pp.1055-1064
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• 2015

We demonstrate a next-generation high-capacity mobile fronthaul based on radio over fiber (RoF) technology, which links between a digital unit and a radio unit supporting two frequency assignments and $2{\times}2$ multiple input, multiple output antennas. To confirm the technical feasibility of a mobile fronthaul, we experimentally investigate its down- and uplink end-to-end performances including the optical and radio frequency (RF) signal path. Frequency-dependent performance deviations, error vector magnitude variations, overall system performance variations caused by optical to electrical conversion, and intermediate frequency to RF conversions are examined. Experimental verifications on multiple LTE uplink signals are performed for the first time. We also demonstrate several commercial mobile Internet services, YouTube video streaming, and file transfers using off-the-shelf mobile devices, through a mobile fronthaul based on RoF.