• Journal of Biosystems Engineering
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• 제25권2호
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• pp.141-150
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• 2000

This study was carried out to de develop a control strategy of a fruit harvesting redundant robot. The method of generating a safe trajectory, which avoids collisions with obstracles such as branches or immature fruits, in the 3D(3-dimension) space using artificial potential field technique and virtual plane concept was proposed. Also, the method of setting reference velocity vectors to follow the trajectory and to avoid obstacles in the 3D space was proposed. Developed methods were verified with computer simulations and with actual robot tests. Fro the actual robot tests, a machine vision system was used for detecting fruits and obstacles, Results showed that developed control method could reduce the occurrences of the robot manipulator located in the possible collision distance. with 10 virtual obstacles generated randomly in the 3 D space, maximum rates of the occurrences of the robot manipulator located in the possible collision distance, 0.03 m, from the obstacles were 8 % with 5 degree of freedom (DOF), 8 % with 6-DOF, and 4% with 7-DOF, respectively.

• Computers and Concrete
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• 제11권6호
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• pp.515-529
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• 2013

The moment-curvature relation for simple bending is a well-studied subject and the classical moment-curvature diagram is commonly found in literature. The influence of axial forces has generally been considered as compression onto symmetrically reinforced cross-sections, thus strain at the reference fiber never has been an issue. However, when dealing with integral structures, which are usually statically indeterminate in different degrees, these concepts are not sufficient. Their horizontal elements are often completely restrained, which, under imposed deformations, leads to moderate compressive or tensile axial forces. The authors propose to analyze conventional beam cross-sections with moment-curvature diagrams considering asymmetrically reinforced cross-sections under combined influence of bending and moderate axial force. In addition a new diagram is introduced that expands the common moment-curvature relation onto the strain variation at the reference fiber. A parametric study presented in this article reveals the significant influence of selected cross-section parameters.

• 한국생산제조학회지
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• 제21권1호
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• pp.58-64
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• 2012

Instead of the surface pattern arranged repeatedly in two axial direction on a plane, we propose double patterns superposing two one-axial linear patterns as a reference target for surface encoding. A upper layer of the superposed pattern is the transparent glass with grooves cut in it at a fixed pitch. The position is sensed by detecting a shift of beam due to difference of a refractive index. And a lower layer is the aluminum with color-coated grooves. The amount of beam reflected on the layer varies according to its targeting position and is detected for encoding. For the above reference pattern, we can detect two-axial positions using only the single beam. Furthermore, the pattern size can be expanded with a size of the detector kept constant, meaning that the measured range can be expanded easily. In this paper, we review the existing optical encoding methods for grid pattern, and discuss the hardware implementation of the suggested surface encoding method.

• 전자공학회논문지D
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• 제35D권12호
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• pp.75-82
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• 1998

체적홀로그램의 저장용량을 향상시키기 위해서 여러 가지 다중화 기법이 제안되고 있는 가운데, 본 논문에서는 각다중화와 공간다중화를 병행한 복합 다중화 시스템을 구현하였다. 기준파의 각도 및 공간상의 위치를 변화시키는 방법으로 스텝 모터를 사용하여 다중 홀로그램을 기록할 수 있었다. 기록 시간 스케줄에 의하여 노출 시간을 조절하므로써 기준파와 물체파 간의 간섭 패턴을 홀로그램에 기록하였다. 3층 300개의 영상을 한 개의 LiNbO₃ :Fe에 기록하였으며 실험 결과를 보였다.

• Current Applied Physics
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• 제18권11호
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• pp.1261-1267
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• 2018

In this paper, an off-axis digital holographic microscopy compensated with self-hologram rotation is presented. The process is implemented via subtracting the unwrapped phase maps of the off-axis parabolic hologram and its rotation $180^{\circ}$ to eliminate the tilt induced by the angle between the spherical object wave O and the plane reference wave R. Merit of the proposed method is that it can be done without prior knowledge of physical parameters and hence can reconstruct a parabolic hologram of $1024{\times}768$ pixels within tens of milliseconds since it doesn't require a digital reference wave. The method is applied to characterize rough gold bumps and the obtained results were compared with those extracted from the conventional reconstruction method. The comparison showed that the proposed method can characterize rough surfaces with excellent contrast and in realtime. Merit of the proposed method is that it can be used for monitoring smaller biological cells and micro-fluidic devices.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.895-901
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• 1993

This paper present controller designs based on the configuration control framework for a redundant manipulator to accomplish the basic task of desired, end-effector motion, while utilizing the redundancy to achieve the additional tasks such as joint motion control, obstacle avoidance, singularity avoidance. etc. A task based decentralized adaptive scheme is then applied for the configuration variables to track some reference trajectories as close as possible. Simulation results for a direct-drive three-link arm in the vertical plane demonstrate its capabilities for performing various useful tasks.

• 대한전기학회논문지
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• 제35권11호
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• pp.511-518
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• 1986

An algorithm for block-decomposition of a linear, time-invariant, discrete large-scale systems is presented, based upon the matrix sign function on Z-plane. The block-decomposition is performed by defining a reference circle, a circular stripe and projection operators. Simulation study shows that the presented algorithm is very useful for multivariable control system's analysis and design.

• 전자공학회논문지D
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• 제34D권11호
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• pp.48-53
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• 1997

Volume hologram was recorded using reference beam form optical fiber taper. A singel mode fiber was chemically etced to make a taper structure, and we showed experimentally that the referencing by the irregular beam pattern from this taper structure could increase the storage density of photorefractive volume hologram. The spatial selectivity of the volume hologram with this method was increased by two times compared to the normal single mode fiber referencing case. A theoretical analysis with randomly phased plane model also confirmed the results.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.90-95
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• 2000

This plan is to suggest the guide-line as a reference focusing on unique image using characteristics of Youngwol-gun, when any type of development is conducted. The study is doing on the present status and analysis for the whole of Youngwol-gun, the basic aim and an establishment of direction for landscape plane, the landscape plan for each rural and urban area(suggestion of guide-line), and the direction for development of landscape administration.

• 한국통신학회논문지
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• 제24권12B호
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• pp.2415-2423
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• 1999

We propose a new optical method which conceals the data of authorized persons by encryption before they are stored or compared in the pattern recognition system for security systems. This proposed security system is made up of two subsystems : a proposed optical encryption system and a pattern recognition system based on the JTC which has been shown to perform well. In this system, each image of authorized persons as a reference image is stored in memory units through the proposed encryption system. And if a fingerprint image is placed in the input plane of this security system for access to a restricted area, the image is encoded by the encryption system then compared with the encrypted reference image. Therefore because the captured input image and the reference data are encrypted, it is difficult to decrypt the image if one does not know the encryption key bit stream. The basic idea is that the input image is encrypted by performing optical XOR operations with the key bit stream that is generated by digital encryption algorithms. The optical XOR operations between the key bit stream and the input image are performed by the polarization encoding method using the polarization characteristics of LCDs. The results of XOR operations which are detected by a CCD camera should be used as an input to the JTC for comparison with a data base. We have verified the idea proposed here with computer simulations and the simulation results were also shown.