• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2017-2019
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• 2000

In recent the XLPE cable has been applied more widely because of its advantages, such as the low-cost and simple installation. For a prefabricated joint, its working time is short, its jointing procedures are simple, and its quality control is easy. Electrical performance targets of our developed 132kV cable accessories has been approved through the type test in accordance with IEC publication 840. This paper describes the developmental effort in terms of the design, structure and results of performance verification tests for 132kV XLPE cable system.

• The Journal of Korea Robotics Society
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• v.14 no.3
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• pp.203-210
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• 2019

This paper proposes a hand-controller mechanism for manually controlled endoscopic surgical instruments. A wire-driven mechanism is typically adapted for endoscopic surgical tools because motors cannot be embedded to the joints due to the size limitation. The wire-driven mechanism requires length control of wires that are pulled and released according to the desired joint angle. It is difficult for the operator to control individual wire lengths intuitively. The hand-controller mechanism should be able to control the wires easily without complex processes. For this purpose, we propose a mechanism that can control the wire lengths with a simple mechanical structure and its optimal design method using genetic algorithm. We show the simulation and experimental results to confirm the proposed mechanism and design methods are useful for the manually controlled endoscopic surgical instrument.

• The Journal of Korea Robotics Society
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• v.16 no.2
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• pp.164-171
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• 2021

This paper proposes a continuum mechanism for manually controlled endoscopic surgical instruments. The wire-driven mechanism is typically adapted for endoscopic surgical tools because motors cannot be embedded to the joints due to the size limitation. However, the conventional wire-driven mechanism has inherent problems caused by redundancy, such as deflection and low precision. It does not have operating force and manipulability for surgery. Therefore, a method to increase the force of the continuum mechanism using a multi-wire with simple mechanical structure is proposed. Moreover, for intuitive operation, a hand-controller mechanism that can manipulate the length of the wire without complex process is proposed. Finally, we show that the proposed mechanism and methods are applicable to endoscopic surgical tools through simple experiments.

• Journal of Power System Engineering
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• v.13 no.2
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• pp.11-17
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• 2009

The heat transfer characteristics of flow through two inclined wire-mesh baffles in a rectangular channel were investigated experimentally with varying the mesh number of wire screens and inclination angle of the baffles. Two different types of wire meshes such as dutch and plain weaves, were used in this experiment. Three kinds of baffle plates with different mesh specifications in the dutch weave and four different kinds in the plain weave were manufactured. Baffles were mounted on bottom wall with varied angles of inclination. Reynolds number was varied from 23,000 to 57,000. It is found that the placement of inclined wire-mesh baffles in the channel affects the heat transfer characteristics by combining both jet impingement and flow disturbance. The wire screen modified the flow structure leading to a change in the heat transfer characteristics. The results show that the baffle plate with the most number of mesh (type SA) has the highest heat transfer rate.

• Journal of Magnetics
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• v.12 no.1
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• pp.7-11
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• 2007

We confirm the validity of the analytic expression for the temperature of the Joule heated nano-wire [C.-Y. You et al. Appl. Phys. Lett. 89, 222513 (2006)] with finite element method. The temperature of the Joule heated nano-wire is essential information for the research of the current induced domain wall movement. The analytic expression includes an adjustable parameter which must be determined. Since the physical origin of the adjustable parameter is simplification of the heat source profile, the validity of the analytic expression must be examined for wide range of the nano-wire structure. By comparison with this analytic expression with the results of full numerical finite element method, the adjustable parameter has been determined. The numerically confirmed adjustable parameter values are in the range of 0.60$\sim$0.69, which is well matched with the theoretically expected one. Furthermore, it is found that the adjustable parameter is a slow varying function of the nano-wire geometry. Based on this numerical confirmation, we can apply the analytic expression for the wide range of the nano-wire geometry with proper adjustable parameters.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.665-675
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• 2019

The wire-wrapped fuel bundle is an assembly design in a sodium-cooled fast reactor. A wire spacer is used to maintain a constant gap between rods and to enhance the mixing of coolants. The wire makes the flow complicated by creating a sweeping flow and vortex flow. The vortex affects the flow field and heat transfer inside the subchannels. However, studies on vortices in this geometry are limited. The purpose of this research is to investigate the vortex flow created in the wire-wrapped fuel bundle. For analysis, a RANS-based numerical analysis was conducted for a 37-pin geometry. The sensitivity study shows that simulation with the shear stress transport model is appropriate. For the case of Re of 37,100, the mechanisms of onset, periodicity, and rotational direction were analyzed. The vortex structures were reconstructed in a three-dimensional space. Vortices were periodically created in the interior subchannel three times for one wire rotation. In the edge subchannel, the largest vortex occurred. This large vortex structure blocked the swirl flow in the peripheral region. The small vortex formed in the corner subchannel was negligible. The results can help in understanding the flow field inside subchannels with sweeping flow and vortex structures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.904-908
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• 2013

When an abnormal condition occurs due to a fault current at a consumer location where electricity is supplied through a high-capacity and high-$T_c$ superconducting(HTS) cable, the HTS cable would be damaged if there is no appropriate measure to protect it. Therefore, appropriate measures are needed to protect HTS cables. The fault-current-limiting HTS cable that was suggested in this study performs an ideal transport current function in normal operations and plays a role in limiting a fault current in abnormal operation (i.e., when a fault current is applied). It has a structure that facilitated its self-current-limiting ability through device change and reconfiguration in the existing HTS cable without extra switching equipment. To complete this structure, it is essential to investigate about the selection of the superconducting wire. Therefore, in this paper, HTS wire using two types of different stabilization layer is compared and examined the stability and current limiting properties under the existence of a fault current.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.70-76
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• 2008

Periodic cellular metals (PCMs) are actively being investigated because of their excellent specific strength and stiffness, and multi-functionality such as a heat disperse structure bearing external loading. The Kagome truss PCM has been proved that it has higher resistance to plastic buckling and lower anisotropy than other truss PCMs. In this paper, the out-of-plane compressive responses of the WBK specimens have been measured, theoretically predicted and numerically analyzed. Three specimens of two-layered WBK are fabricated and tested for measuring the responses. The peak stress of compressive behavior and effective elastic modulus are predicted based on the equilibrium equation and elastic energy conservation. Moreover, the structure of the specimen is modeled using the commercial mesh generation code, PATRAN and the finite element analysis for the model under the compression is carried out using the commercial FE code, ABAQUS. Finally, the obtained results are compared with each other to analyze the compressive characteristics of Wire-woven Bulk Kagome (WBK).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.137-142
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• 2017

Recently, the reduction of vehicle weight has been increasingly studied, in order to enhance the fuel efficiency of passenger cars. In particular, the seat frame is being studied actively, owing to considerations of driver safety from external impact damage. Therefore, this study focuses on high strength steel sheet (SPFC980)/polymer heterojunction hybrid materials, and their performance in regards to impact energy absorption. The ratio of impact energy absorption was observed to be relatively higher in the SPFC980/polymer hybrid materials under the impact load. This was found by calculating the equivalent flexural rigidity, which is the bending effect, according to the Castigliano theorem. An efficient wire-web structure was investigated through the simulation of different wire-web designs such as triangular, rectangular, octagonal, and hexagonal structures. The hexagonal wire-web structure was shown to have the least impact damage, according to the simulations. This study can be utilized for seat frame design for passengers' safety, owing to efficient impact absorption.

• Korean Journal of Materials Research
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• v.22 no.5
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• pp.237-242
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• 2012

We report on the NO gas sensing properties of Al-doped zinc oxide-carbon nanotube (ZnO-CNT) wire-like layered composites fabricated by coaxially coating Al-doped ZnO thin films on randomly oriented single-walled carbon nanotubes. We were able to wrap thin ZnO layers around the CNTs using the pulsed laser deposition method, forming wire-like nanostructures of ZnO-CNT. Microstructural observations revealed an ultrathin wire-like structure with a diameter of several tens of nm. Gas sensors based on ZnO-CNT wire-like layered composites were found to exhibit a novel sensing capability that originated from the genuine characteristics of the composites. Specifically, it was observed by measured gas sensing characteristics that the gas sensors based on ZnO-CNT layered composites showed a very high sensitivity of above 1,500% for NO gas in dry air at an optimal operating temperature of $200^{\circ}C$; the sensors also showed a low NO gas detection limit at a sub-ppm level in dry air. The enhanced gas sensing properties of the ZnO-CNT wire-like layered composites are ascribed to a catalytic effect of Al elements on the surface reaction and an increase in the effective surface reaction area of the active ZnO layer due to the coating of CNT templates with a higher surface-to-volume ratio structure. These results suggest that ZnO-CNT composites made of ultrathin Al-doped ZnO layers uniformly coated around carbon nanotubes can be promising materials for use in practical high-performance NO gas sensors.