• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.85-90
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• 1998

This paper describes the breakdown characteristics of GIS by the free conducting particles under alternating voltage. If the conducting particles are present within the GIS, they can cause decrease in breakdown voltages. Various materials and sizes of free conducting particles were used to study the liftoff electric field and breakdown voltage. The measured lift-off electric fields were compared with the calculated ones for copper, steel and aluminium wire-type conducting particles. As an experimental result, it is shown that the breakdown voltages of the GIS chamber with conducting particles were lower than those without conducting particles, and were markedly dependent on the particle material and the particle sizes. Free conducting particles are important factor in particle-triggered breakdown of the GIS.he GIS.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.176-179
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• 2005

The increasing demand for high density packaging technologies and the evolution to mixed digital and analogue devices has been the con-set of increasing research in thin film multi-layer technologies such as the passive components integration technology. In this paper, Cu and TaO thin film with RF sputtering was deposited for spiral inductor and MOM capacitor on the $SiO_2$/Si(100) substrate. MOM capacitor and spiral inductor were fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, important devices for mobile communication system. Based on the high-Q values of passive components, MOM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and 5 dB for a 900 MHz filter. This paper also discusses a analysis and practical design to thin-film L-C band pass filter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.431-434
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• 1998

Platinum-Cobalt alloy thin films were deposited on Al$_2$O$_3$ substrate by r.f. cosputtering for RTD temperature sensors. We made Pt-Co alloy resistance patterns on the Al$_2$O$_3$ substrate by lift-off method and investigated the physical and electrical characteristics of these films under various conditions (the input power, working vacuum, annealing temperature, thickness of thin films) and also after annealing these films. At input power of Pt : 4.4 W/$\textrm{cm}^2$, Co : 6.91 W/$\textrm{cm}^2$, working vacuum on and annealing conditions of 1000 $^{\circ}C$ and 60 min, the resistivity and the sheet resistive thin films were 15 ${\mu}$$\Omega$$.$cm and 0.5 $\Omega$/$\square$, respectively. The TCR value of Pt-Co a films was measured with various thickness of thin films and annealing temperature. T TCR value is gained under condition 3000${\AA}$ of thin films thickness and 1000$^{\circ}C$ of temperature. These results indicate that Pt-Co alloy thin films have potentiality for the wide temperature ranges.

• Wind and Structures
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• v.22 no.5
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• pp.595-616
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• 2016

Providing high starting torque and efficiency simultaneously is a significant challenge for vertical axis wind turbines (VAWTs). In this paper, a new approach is studied in order to modify VAWTs performance and cogging torque. In this approach, J-shaped profiles are exploited in the structure of blades by means of eliminating the pressure side of airfoil from the maximum thickness toward the trailing edge. This new profile is a new type of VAWT airfoil using the lift and drag forces, thereby yielding a better performance at low TSRs. To simulate the fluid flow of the VAWT along with J-shaped profiles originated from NACA0018 and NACA0030, a two-dimensional computational analysis is conducted. The Reynolds Averaged Navier-Stokes (RANS) equations are closed using the two-equation Shear Stress Transport (SST) turbulence model. The main objective of the study is to investigate the effects of J-shaped straight blade thickness on the performance characteristics of VAWT. The results obtained indicate that opting for the higher thickness in J-shaped profiles for the blade sections leads the performance and cogging torque of VAWT to enhance dramatically.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.8
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• pp.580-588
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• 2009

This paper summarizes the experimentally-measured performance of small-scale, vertical-axis wind turbine for the purpose of improving the aerodynamic efficiency and its controllability. The turbine is designed to have a Savonius-Type rotor with an inlet guide-vane and an side guide-vane so that it achieves a higher efficiency than any lift- or drag-based turbines. The main design factors for this high-efficient, vertical wind turbine are the number of blades (Z), and the aspect ratio of Height/Diameter (H/D) among many. The basic model has the diameter of 580mm, the height of 464mm, and the blade number of 10. The maximum power coefficient of 0.50 was experimentally measured for the above-mentioned specifications. The inlet-guide vane ensures the maximum efficiency when the angle of attack to the rotor blade lies between $15^{\circ}$ and $20^{\circ}$. This experimental results for the vertical-axis wind turbine can be applied to the preliminary design of turbine output curve based on the wind characteristics at the proposed site by controlling its aerodynamic performance given as a priori.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.5
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• pp.421-430
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• 2018

The shape of a yacht sail made of thin fabric materials is easily deformed by wind speed and direction and it is affected by the deformation of the standing rig such as mast, boom, shrouds, stays and spreaders. This deformed sail shape changes the air flow over the sail, it makes the deformation of the sail and the rig again. To get a sail performance accurately these interactive behavior of sail system should be studied in aspects of the aerodynamics and the fluid-structure interaction. In this study aerodynamic analysis for the sail system of a 30 feet sloop is carried out and the obtained dynamic pressure on the sail surface is applied as the loading condition of the calculation to get the deformations of the sail shape and the rig. Supporting forces by rig are applied as boundary condition of the structure deformation calculations. And the characteristics of the air flow and the dynamic pressure over the deformed sail shape is investigated repeatedly including the lift force and the location of CE.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.343-348
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• 2006

Number of researches on efficient terminal operation system applying RFID(Radio Frequency Identification) are on progress. However, RFID has limitations on tracking and providing accurate positions of containers. In this paper, to enhance the performance of the integrated terminal operation system, an efficient loading management of yard is proposed by applying RFID-based RTLS(Real Time Locating System) that provides real-time accurate positions of containers. We found that a group-based sequence system is more efficient than the existing individual sequence number system in the container yard. In the group-based sequence system, the containers in the same group should have similar characteristics such as port of destination(POD), size, weight, etc. In order to run this system, we have proposed the parameters to the unspecified N bytes of RFID tag which are specified in ISO 18000-7. And, this paper proposed a development of integrated operation system of container terminal using RFID for reducing the ship turnaround time in ubiquitous port environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.335-338
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• 1997

Platinum-Cobalt alloy thin films were deposited on A1$_2$O$_3$substrate by magnetron cosputtering for RTD temperature sensors with wide temperature ranges. We made Pt-Co alloy resistance patterns on the A1$_2$O$_3$substrate by lift-off method and fabricated Pt-Co alley RTD temperature sensors by using Pt-wire, Pt-paste. We investigated the physical and electrical characteristics of theme films under various conditions, input power, working vacuum, annealing temperature and time, and also after annealing these films. The resistivity and sheet resistivity of these films were decreased with increasing the annealing temperature. At input power of Pt : 4.4 W/cm$^2$, Co : 6.91 W/cm$^2$, working vacuum of 10 mTorr and annealing conditions of 800$^{\circ}C$ and 60 min, the resistivity and sheet resistivity of Pt-Co thin films was 15${\mu}$$\Omega$$.$cm and 0.5$\Omega$/ , respectively, and the TCR value of Pt-Co alloy thin films with thickness of 3000${\AA}$ was 3740ppm/$^{\circ}C$ in the temperature range of 25∼600$^{\circ}C$. These results indicate that Pt-Co alloy thin films hove potentiality for the RTD with wide temperature ranges.

• Textile Coloration and Finishing
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• v.8 no.5
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• pp.84-89
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• 1996

This study carried out batch and continuous experiments using calcium hydroxide as neutralization agent and immobilization media for removing the ethylene glycol in the pretreated polyester weight loss wastewater. The $TCOD_{Mn}$ concentration in the treated wastewater using culture of iramobilization and suspension for the synthetic wastewater were found as 650mg/l and 1,250mg/l after 48hours, respectively. SVI(Sludge Volume Index) and $TCOD_{Mn}$ concentration were 74 and 73mg/l at optimum F/M ratio, 1.32kg-TCO $D_{Mn}$ /day. kg-MLVSS. The $TCOD_{Mn}$ concentration and removal efficiency were 213mg/l and 93.5% by continuous experiments in the air-lift bioreactor, respectively. The $TCOD_{Mn}$ concentration was 82mg/l, and also the MLVSS concentration was 2,550mg/l, when the volumetric loading rate was 3.04kg-$TCOD_{Mn}/m^{2}$ day for real polyester weight loss wastewater.

• Wind and Structures
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• v.23 no.3
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• pp.171-189
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• 2016

An adjustable, louver-type wind barrier was introduced in this study for improving the running safety and ride comfort of train on the bridge under the undesirable wind environment. The aerodynamic characteristics of both train and bridge due to this novel wind barrier was systematically investigated based on the wind tunnel tests. It is suggested that rotation angles of the adjustable blade of the louver-type wind barrier should be controlled within $90^{\circ}$ to achieve an effective solution in terms of the overall aerodynamic performance of the train. Compared to the traditional grid-type wind barrier, the louver-type wind barrier generally presents better aerodynamic performance. Specifically, the larger decrease of the lift force and overturn moment of the train and the smaller increase of the drag force and torsional moment of the bridge resulting from the louver-type wind barrier were highlighted. Finally, the computational fluid dynamics (CFD) technique was applied to explore the underlying mechanism of aerodynamic control using the proposed wind barrier.