• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_1
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• pp.953-959
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• 2022

In this paper, the design result of robotic tools and the development of robot control system for chemical coupler assembly are presented. This research aims to eliminate the risk of chemicals exposed to human operators by developing the robotic tools and robot automation system for chemical tank lorry unloading that were done manually. Due to tight tolerance between couplers, even small pose error may result in very large internal force. In order to resolve the problem, the 6-axis compliance device is employed, which can provide not only enough compliance between couplers but also F/T sensing. The 6-axis compliance device having large force and moment capacity is designed. A simple linear gripper with rack-and-pinion is designed to grasp two sizes of couplers. The proposed robot automation system consists of 6-DOF collaborative robot with offset wrist, 6-axis compliance device with F/T sensing, linear gripper, and two robot visions.

• Steel and Composite Structures
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• v.29 no.2
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• pp.257-272
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• 2018

The research of shear connectors composed from mechanical couplers with rebar anchors, embedded in concrete, and steel bolts, as a mean of shear transfer in composite connections is presented in the paper. Specific issues related to this type of connections are local concrete pressure in the connector vicinity as well as the shear flow along the connector axis. The experimental research included 18 specimens, arranged in 5 series. Nonlinear numerical analyses using Abaqus software was conducted on corresponding FE models. Different failure modes were analysed, with emphasis on concrete edge failure and bolt shear failure. The influence of key parameters on the behaviour of shear connector was examined: (1) concrete compression strength, (2) bolt tensile strength and diameter and (3) concrete edge distance. It is concluded that bolted shear connectors with mechanical couplers have sufficient capacity to be used as shear connectors in composite structures and that their behaviour is similar to the behaviour of post installed anchors as well as other types of connectors anchored without the head.

• Journal of the Optical Society of Korea
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• v.9 no.3
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• pp.99-102
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• 2005

Directional couplers of gradient-index plastic optical fibers were fabricated and characterized. In particular, we have employed a core-facet technique to make the directional couplers, which require mechanical side polishing and linkage. We have measured insertion loss, excess loss, and coupling ratio of the fabricated couplers as a function of polishing depth and coupling length. We found that polishing depth of $\~300{\mu}m$ and coupling length of $\~35mm$ are optimum conditions for minimizing the insertion and excess losses and for achieving 1: 1 coupling ratio.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.11-19
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• 2022

In this study, in order to improve the splice performance of mechanical couplers, two new mechanical couplers with different connection modes were developed with rebar(SD400). The stress analysis of mechanical couplers with two different connection modes was carried out. Uniaxial tensile tests were carried out with type of steel, connection mode and the slope length of internal fastener as variables to analyze the influence on the maximum tensile strength. Building upon this previous work, the specimens that met the code in uniaxial tensile test were fabricated and static loading test and cyclic loading test were performed on the basis of Korean code(KS D 0249). The results of this research are as follows; (1) The tensile strength of steel and the slope length of internal fasteners have a certain influence on the maximum tensile strength. (2) The connection mode has some influence on the stiffness, slip and stiffness reduction rate of the connecting rebars. The results verify the feasibility of the proposed enhanced mechanical coupler in the field.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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• pp.909-915
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• 2022

In this paper, a robot automation technology for chemical tank lorry unloading is presented. Handling chemical coupler between tank lorry and ACQC system may be hazardous or toxic to human operators, therefore robot automation is essential. Due to tight tolerance between couplers, even small pose error may result in very large internal force. In order to resolve the problem, compliance between male and female couplers should be introduced with 6-axis compliance device with F/T sensing. The proposed robot automation system consists of a collaborative robot, 6-ax is compliance device with F/T sensing, linear gripper, and robot vision. The position/force control algorithm and experimental results for assembling chemical couplers are presented.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.420-427
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• 1993

Dielectric thin film mirrors are embedded in multimode and single-mode fibers by a fusion splicing technique. The fibers with $45{\circ}$ angled embedded mirrors serve as ultra-compact directional couplers with low excess optical loss of 0.2 dB for multimode and 0.5 dB for single mode at 1.3 ${\mu}m$ and excellent mechanical properties. The reflectance is wavelength dependent and strongly polarization depencient. Far-field scans of the reflected output power measured with a white-light source show a pattern which is almost circularly symmetric with aspect ratio of 1.09 at 5% of the peak power. The splitting ratio in a multimode coupler measured with a diode laser source is much less dependent on input coupling conditions than in conventional fused biconical-taper couplers, indicating that these couplers are less susceptible to modal noise occuring in optical fiber communication systems. Spectral properties of multilayer internal mirrors normal to the fiber axis have been investigated experimentally, and a matrix analysis has been used to explain the results.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.214-218
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• 2007

With the development of high speed railway, traction motors play a critical role in the operation of railway vehicle. This paper describes the use of 1000 pF coupler as a on-line partial discharge (PD) measurement for the assessment of railway traction motor. The PD tests are performed with developed PD analyzer and the 5 model coils such as thermal, electrical, mechanical and environmental aging respectively at various AC voltages. On-line PD tests using 1000 pF couplers show that PD patterns can be detected successfully at 2.3 kV.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2290-2295
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• 2005

In this paper, it is developed simulator system of 3 D.O.F parallel robot for educate of expertness. This simulator system is composed of three parts ? 3 D.O.F parallel robot, controller (hardware) and software. First, basic structure of the robot is 3 active rotary actuator that small geared step motor with fixed base. An input-link is connected to this actuator, and this input-link can connect two ball joints. Thus, two couplers can be connected to the input-link as a pair. An end-plate, which is jointed by a ball joint, can be connected to the opposite side of the coupler. A sub-link is produced and installed to the internal spring, and then this sub-link is connected to the upper and bottom side of the coupler in order to prevent a certain bending or deformation of the two couplers. The robot has the maximum diameter of 230 mm, 10 kg of weight (include the table), and maximum height of 300 mm. Hardware for control of the robot is composed of computer, micro controller, pulse generator, and motor driver. The PC used in the controller sends commands to the controller, and transform signals input by the user to the coordinate value of the robot by substituting it into equations of kinematics and inverse kinematics. A controller transfer the coordinate value calculated in the PC to a pulse generator by transforming it into signals. A pulse generator analyzes commands, which include the information received from the micro controller. A motor driver transfer the pulse received from the pulse generator to a step motor, and protects against the over-load of the motor Finally, software is a learning purposed control program, which presents the principle of a robot operation and actual implementation. The benefit of this program is that easy for a novice to use. Developed robot simulator system can be practically applied to understand the principle of parallel mechanism, motors, sensor, and various other parts.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.120-126
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• 2006

A grating-assisted fiber coupler(GAFC), which consists of a thin-film waveguide with grating and circular optical fiber, is proposed and the optimized power coupling is evaluated by using a technique amenable to rigorous longitudinal modal transmission-line theory(L-MTLT). In addition, novel criteria to couple an optical signal incident through the grating waveguide to a single-mode optical fiber are proposed. The numerical result reveals that the optimized power coupling occurs at minimum-gap condition between rigorous modes rather than for the conventional phase-matching condition.

• Journal of the Optical Society of Korea
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• v.8 no.4
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• pp.149-155
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• 2004

Newly developed modal transmission-line theory(MTLT) is used to analyze rigorously the optical power distribution in grating-assisted directional couplers(GADCs) with three guiding channels. By defining a novel coupling efficiency ${\eta}$ amenable to the rigorous analytical solutions of modal transmission-line theory, we explicitly evaluate the power coupling and distribution of TM modes. The results reveal that the incident power is sensitively partitioned through three output channels in terms of such grating parameters as the grating period, the duty cycle, and the operating wavelength.