• Journal of the Korean Society of Industry Convergence
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• v.23 no.1
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• pp.41-48
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• 2020

Currently, the industry uses MODBUS communication method using RS485 as a communication method used when constructing distributed equipment and networks. However, this method has a rather good transmission and reception distance, but has a disadvantage of being a half-duplex communication method. Therefore, there is a great need for a full-duplex communication method that can simultaneously transmit and receive two-wire communications. Therefore, in this paper, we propose a new communication hardware equipment that can implement full-duplex communication method by communication signal level to overcome the disadvantage of communication speed. The proposed communication hardware is a structure that can transmit and receive at the same time on the same communication line in two equipments communicating in a two-wire system. The characteristic of this communication hardware is that the transmitter generates two-level signal for data transmission, but the receiver generates three-level electric signal according to the status of the transmission data generated by the receiver. The data transmission signal information of the receiver is present at the same time. Therefore, the receiving side can analyze the received signal based on the information on the current transmission signal and can analyze the signal only in the two communicating devices, so it can be seen that the communication security is very excellent.

• Journal of the Semiconductor & Display Technology
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• v.15 no.4
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• pp.61-66
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• 2016

This paper presents the implementation for a network structure of railway cars using a point to point communication. Most of network's representative specifications for a train are the FIP (Field Bus), MVB (Multifunction Vehicle Bus), CAN and WTB (Wire Train Bus) which is used by ALSOM, SIEMENS and BOMBADIER as major in this field. These networks in a physical layer use a multi-drop method, connected from $1^{st}$ car to $n^{th}$ car of a train through a cable without any extra services such as an electric part, amplifier. However waveforms which is passed through a long cable in the multi-drop are distorted by a capacitance or resistance of the cable or environments. Also since using a cable connected directly from $1^{st}$ car to $n^{th}$ car, if over two trains make double head, it isn't easy to distinguish ID for each railway cars. So by using the point to point network per each car, it is able to reduce a distortion. Also since reducing distortion, this communication speed can be been higher and transmit and receive any packets more stably. Using proposed token in a packet, this can make ID per each railway car automatically. Finally experimental results show the good performance and effectiveness of the proposed method.

• The Journal of Korea Robotics Society
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• v.15 no.3
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• pp.212-220
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• 2020

This paper deals with a strategy of gain optimization for the kinematic control algorithm of a wire-driven surgical robot. The proposed controller consists of the closed-loop inverse kinematics with the back-calculation method. The closed-loop inverse kinematics has 18 PID control gains, and the back-calculation method has 6 gains. An efficient strategy is designed to optimize 18 values first and then the remaining 6 values. The optimal gain sets are searched under the step input with performance indices. In this gain optimization, the objective function is defined as the minimum value of signal-to-noise ratio of the performance indices for 6 DoF (Degree-of-Freedom) motion that is based on the Taguchi method, and the constraints are applied to obtain stable responses for each motion evenly. The gain sets obtained are verified by simulations using the test trajectories. In comparative results, the optimal gain value based on the performance index combined with ISE (integral of square error) and settling time showed the best control performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.264-267
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• 2002

This paper presents the design of a pipelined virtual output queue routing engine for an advanced input-queued ATM switch, which has a serial cross bar structure. The proposed routing engine has been designed for wire-speed routing with a pipelined buffer management. It provides the tolerance of requests and grants data transmission latency between the routing engine and central arbiter using a new request control method that is based on a high-speed shifter. The designed routing engine has been implemented in a field programmable gate array (FPGA) chip with a 77MHz operating frequency, 16$\times$16 switch size, and 2.5Gbps/port speed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.6 s.261
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• pp.694-700
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• 2007

Recently, a new cellular metal, WBK(Wire woven Bulk Kagome) has been introduced. WBK is fabricated by assembling metal wires in six directions into a Kagome-like truss structure and by brazing it at all the crossings. Wires as the raw material are easy to handle and to attain high strength with minimum defect. And the strength and energy absorption are superior to previous cellular metals. Therefore, WBK seems to be promising once the fabrication process for mass production is developed. In this paper, an upper bound solution for the mechanical properties of the bulk WBK under compression is presented. In order to simulate uniform behavior of WBK consisted of perfectly uniform cells, a unit cell of WBK with periodic boundary conditions is analyzed by the finite element method. In comparison with experimental test results, it is found that the solution provides a good approximation of the mechanical properties of bulk WBK cellular metals except for Young's modulus. And also, the brazing joint size does not have any significant effect on the properties with an exception of an idealized thin joint.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.330-334
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• 2004

In this paper, we studied on the fire dispersive patterns and the fire progress at the power cord sets for low voltage appliances in the wall-model. For the experiment, we manufactured a wall-model and applied the external flame at the power cord sets. From the results, short-circuit of the power cord sets was haunted by the external flame it was disconnected with the flashing and the scattering. The fire progress on the polyvinyl chloride insulated flexibel cords is not observed because the ignition energy decreases. In case of rubber insulated flexible cords, however, the fire was progressed continuously. Molten marks were formed at a two electric wire by continuous electric discharge in power source part. A large molten mark was formed in load part. And the columnar structure and voids were observed in molten wire.

• Journal of Powder Materials
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• v.17 no.6
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• pp.464-469
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• 2010

The Cu nanofluid in ethylene glycol was prepared by electrical explosion of wire, a novel one-step method. The X-ray diffraction, field emission scanning electron microscope and transmission electron microscope were used to study the properties of Cu nanoparticles. The results showed that the nanoparticles were consisted of pure face-centered cubic structure and near spherical shape with average grain size of 65 nm. Ultraviolet-visible spectroscopy (UV-Vis) confirmed Cu nanoparticles with a single absorbance peak of Cu surface plasmon resonance band at 600 nm. The nanofluid was found to be stable due to high positive zeta potential value, +51 mV. The backscattering level of nanofluid in static stationary was decreased about 2% for 5 days. The thermal conductivity measurement showed that Cu-ethylene glycol nanofluid with low concentration of nanoparticles had higher thermal conductivity than based fluid. The enhancement of thermal conductivity of nanofluid at a volume fraction of 0.1% was approximately 5.2%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2785-2792
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• 2013

An elevator is driven by the friction between the pulley and wire rope. A balancing counter weight is connected to the elevator car with a wire rope. This structure is essential to drive elevators while it always has weight unbalance problems on each side. The overbalance-ratio of elevators may be an important factor for safety and structural efficiency; however, it is not yet clearly defined in the Requirements of Korea Elevator Inspection. This paper describes these "weight unbalance ratio" for control of elevators to reduce the number of accidents. It includes the analysis of current elevator maintenance situations and also proposes some fundamental improvement schemes for safety.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.55-55
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• 2010

We use ab initio density functional theory to determine the effect of bundling on the equilibrium structure, electronic and magnetic properties of $Mo_6S_{9-x}I_x$nanowires with x = 0, 3, 4.5, 6. Each unit cell of these systems contains two $Mo_6S_{6-x}I_x$ clusters connected by S3 linkages to form an ordered linear array. Due to the bi-stability of the sulfur linkages, the total energy of the nanowires exhibits typically many minima as a function of the wire length. We find that nanowires can switch over from metallic to semiconducting by applying axial stress. Structural order is expected in bundles with x=0 and x=6, since there is no disorder in the decoration of the Mo clusters. In bundles with other stoichiometries, we expect structural disorder to occur. We find the optimum inter-wire distance to depend sensitively on the orientation of the wires, but only weakly on x. It is also found that the electronic properties of nanowires are affected strongly due to bundling of nanowires exhibiting very unusual Fermi surfaces. Furthermore, ferromagnetic behaviors are observed in selected stable and many more unstable atomic arrangements in nanowire bundles.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.214-221
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• 1987

The purpose of this study is augmentation of heat transfer without additional power in the case of rectangular air jet which impinges vertically on the heating surface. The experimental results are obtained heat transfer augmentation of a two-dimensional impinging jet using the surface roughness of transverse repeated-rib type. The integral average heat transfer coefficient of ribbed plate is about two times larger than that of flat plate. In order to supplement the information about the mechanism of heat transfer augmentation, the flow structure in the stagnation region is visually studied by using the smoke wire technique. The heat transfer augmentation is due to the effect of stretching of large scale vortex in the stagnation region.