• The Journal of Korea Robotics Society
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• v.15 no.2
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• pp.100-106
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• 2020

In the agricultural field, interests in research using robots for fruit harvesting are continuously increasing. Dual arm manipulators are promising because of its abilities like task-distribution and role-sharing. To operate it efficiently, the task sequence must be planned adequately. In our previous study, a collision-free path planning method based on a genetic algorithm is proposed for dual arm manipulators doing tasks cooperatively. However, in order to simplify the complicated collision-check problem, the movement between tasks of two robots should be synchronized, and thus there is a problem that the robots must wait and resume their movement. In this paper, we propose a heuristic algorithm that can reduce the total time of the optimal solution obtained by using the previously proposed genetic algorithm. It iteratively desynchronizes the task sequence of two robots and reduces the waiting time. For evaluation, the proposed algorithm is applied to the same work as the previous study. As a result, we can obtain a faster solution having 22.57 s than that of the previous study having 24.081 s. It will be further studied to apply the proposed algorithm to the fruit harvesting.

• Journal of the Korean Home Economics Association
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• v.36 no.4
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• pp.163-178
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• 1998

This study is to identify the influence of dual-earner couples' job related variables on marital satisfaction and quality of life. For the data set 228 dual-earner couples living in Pusan, Korea were chosen. The data were analyzed using M, SD, t-test, one-way ANOVA, scheffe test, and path analysis. The findings of this study are as follows; First, the level of marital satisfaction and quality of life are higher for husbands than wives. Second, for husbands, the level of marital satisfaction were differed by husbands' housework participation, husbands' support, and job satisfaction. Whereas for wives, the level of marital satisfaction were differed by husbands' house work participation, husbnand's job stressorors, and wives' employment motivation. Third, for husbands, the level of quality of life were differed by husbands' housework participation, husbands' support, job satisfaction, and husbands' job stressors. Whereas for wives, the level of quality of life were differed by income, husbands' support, job satisfaction, working hours, husbands' job stressorors, and wives' employment motivation. Fourth, for husbands, marital satisfaction, job satisfaction, and working hours have significant direct effect on quality of life. Besides, husbands' job stressors, and husbands' and husbands' housework participation, and job satisfaction are indirectly associated with quality of life.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.366-371
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• 2009

A realization for an accurate position detecting system of a moving target in two dimensional plane using dual line CCDs and photometric interpolation is presented. The system is realized that the infrared LEDs are utilized for lighting source, a target size is recognized by the scanned data from CCD owing to blocking the radiated light path by placing the target between CCD and lighting source, a coordinate on the plane is found by plane trigonometry formed by the moving target and two CCD sensors, and the former scan data is used for the coordinate iteratively and the photometric interpolation is applied to sub-pixel of scanned image. The experimental results show that the experiment results in a success rate about 3 different size targets, 3, 5 and 7mmm on the test plane $210{\times}373mm$. The moving target positioning detected success rate is 93% in 3mm target, 5mm is 95.3%, and 7mm is 95.8% respectively. The photometric interpolation is enhanced to 1.5% in comparison to be unused.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.193-194
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• 2006

A solid freeform fabrication (SFF) system using selective laser sintering (SLS) is currently recognized as a leading process and SLS extends the applications to machinery and automobiles due to the variousmaterials employed. In order to develop a more elaborate and rapid system for fabricating large objects compared to existing SLS, this study employs a new selective dual-laser sintering (SDLS) process. Also, this paper will address development of an SFF system which employs the dual laser system and the unique scanning device. Experiments were performed to evaluate the effect of a scanning path and fabrication parameters on sintering process and to fabricate the various 3D objects using polymer powder.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.39-46
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• 2008

High precision machining technology has become one of the important parts in the development of a precision machine. Such a machine requires high speed on a large workspace as well as high precision positioning. For machining systems having a long stroke with ultra precision, a dual-stage system including a global stage (coarse stage) and a micro stage (fine stage) is designed in this paper. Though linear motors have a long stroke and high precision feed drivers, they have some limitations for submicron positioning. Piezo-actuators with high precision also have severe disadvantage for the travel range, and the stroke is limited to a few microns. In the milling experiments, the positional accuracy has been readily achieved within 0.2 micron over the typical 20 mm stroke, and the path error over 2 micron was reduced within 0.2 micron. Therefore, this technique can be applied to develop high precision positioning and machining in the micro manufacturing and machining system.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.67-75
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• 2013

The advantages of the orthogonal frequency division multiplexing (OFDM) are high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. To further utilize vast channel capacity of the multiuser OFDM, one has to find the efficient adaptive subchannel and bit allocation among users. In this paper, we compare the performance of the linear programming dual of the 0-1 integer programming formulation with the existing convex optimization approach for the optimal subchannel and bit allocation problem of the multiuser OFDM. Utilizing tight lower bound provided by the LP dual formulation, we develop a primal heurisitc algorithm based on the LP dual solution. The performance of the primal heuristic is compared with MAO, ESA heuristic solutions, and integer programming solution on MATLAB simulation on a system employing M-ary quadrature amplitude modulation (MQAM) assuming a frequency-selective channel consisting of three independent Rayleigh multi-paths.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.411-421
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• 2002

In this paper, we present a new survivor path memory management method and a dedicated hardware architecture for the design of high-speed Viterbi decoders in modern digital communication systems. In the proposed method, a novel use of k-starting node number deciding circuits enables to acheive the immediate traceback of the merged survivor path from which we can decode output bits, and results in smaller survivor path memory size and processing delay time than the previously known methods. Also, in the proposed method, the survivor path memory can be constructed with ease using a simple standard dual-ported memory since one read-pointer and one write-pointer, that are updated at the same rate, are required for managing the survivor path: the previously known algorithms require either complex k-ported memory structure or k-times faster read capability than write. With a moderate hardware cost for immediate traceback capability the proposed method is superior to the previously known methods for high-speed Viterbi decoding.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.2
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• pp.140-145
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• 2002

A new CMOS buffer removing short-circuit power consumption is proposed. The gate-driving signal of the pull-up(pull-down) transistor at the output is controlled by delayed internal signal to get tri-state output momentarily by shunting off the path of the short-circuit current. The SPICE simulation results verified the operation of the proposed buffer and showed the enhancement of the power-delay product at 3.3V supply voltage about 42% comparing to the conventional tapered CMOS buffer(1).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.8
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• pp.1209-1217
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• 1997

This paper proposes the modeling of the dynamics of two cooperating robot manipulators performing the assembly job such as peg-in-hole while coordinating the payload along the desired path. The mass and moment of inertia of the manipulators and the payload are assumed to be unknown. To control the uncertain system, a robust control algorithm based on the computed torque control is proposed. Usually, the robust controller requires high input torques such that it may face input saturation in actual application. In this reason, the robust control algorithm includes fuzzy logic such that the magnitude of the input torque of the manipulators is controlled not to go over the hardware saturation while keeping path tracking errors bounded. A numerical example using dual three degree-of-freedom manipulators is shown.

• Structural Engineering and Mechanics
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• v.5 no.5
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• pp.491-505
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• 1997

This paper deals with the formulation and solution of a wide class of structures, in the presence of both geometric and material nonlinearities, as a particular mathematical programming problem. We first present key ideas for the nonholonomic (path dependent) rate formulation for a suitably discretized structural model before we develop its computationally advantageous stepwise holonomic (path independent) counterpart. A feature of the final mathematical programming problem, known as a nonlinear complementarity problem, is that the governing relations exhibit symmetry as a result of the introduction of so-called nonlinear "residuals". One advantage of this form is that it facilitates application of a particular iterative algorithm, in essence a predictor-corrector method, for the solution process. As an illustrative example, we specifically consider the simplest case of plane trusses and detail in particular the general methodology for establishing the static-kinematic relations in a dual format. Extension to other skeletal structures is conceptually transparent. Some numerical examples are presented to illustrate applicability of the procedure.