• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.441-442
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• 2002

Chemical mechanical polishing (CMP) is a manufacturing process that uses controlled wear to planarize dielectric and metallic layers on silicon wafers. CMP experiments revealed that a sub-ambient film pressure developed at the wafer/pad interface. Additionally, dishing occurs in CMP processes when the copper-in-trench lines are removed at a rate higher than the barrier layer. In order to study dishing across a stationary wafer during polishing, dishing maps were created. Since dishing is a function of the total contact pressure resulting from the applied load and the fluid pressure, the hydrodynamic pressure model was refined and used in an existing model to study copper dishing. Density maps, highlighting varying levels of dishing across the wafer face at different radial positions, were developed. This work will present the results.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.152-154
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• 2001

Recently the extensive use of composite insulators for transmission lines can ultimately be justified only on long-term qualification tests. Especially, it is possible for the Polymer insulator to be aged in according to the environment in which it is used this may bring about the decrease of the duration of voltage application. So, this paper deals with aging property of the polymer insulator installed at real transmission line in the industry area. The contact angle, arc test, tracking test were measured for acquiring the degradation characteristics of silicone rubber and the SEM, XRF, FT-IR tests were measured for analyzing the crack and components. Also the surface leakage current of the polymer insulator was compared with that of the porcelain insulator. Finally, we knew that the aging property was not appeared during seven months at real transmission line in the industry area.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1431-1436
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• 2017

The high-speed railway of catenary system, supplies a stable electric power supply to the train by satisfying the special conditions between pantograph and trolley wire, which operates more than 250km/h mutually sliding and feeding electric lines. According to Korean Railway Standard KRS PW 0026-13 (R), the standard for the grip strength of the dropper clamp in conventional line is established, but the high-speed railway line is not yet. When the grip strength of the dropper clamp is detached from the catenary line of the high-speed railway line, various problems may occur, such as damage to the pantograph due to the collision and arcing. In this paper, it is expected to be used as a basic data for establishing the durability criteria of the high-speed railway dropper clamp by verifying the dropper clamp on the Gyeong-bu and Honam high-speed line.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.70-77
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• 2003

The centerless through-feed grinding is performed by passing the workpiece between the grinding wheel and the regulating wheel. So, the amount of removed material around the leading end, of the workpiece is always more than that around the trailing end until the leading end leaves the grinding wheel. Because of this, there are differences in diameters along the workpiece axis during grinding, and workpiece axis is not parallel to the grinding wheel axis and the contact lines between the workpiece and wheels. Thus the ground workpiece shows tapering error inherently. To eliminate this error, the workpiece axis must be kept to be parallel to the grinding wheel axis. And, the direction of the workpiece axis can be controlled by the work-rest blade. Therefore, the effects of work-rest blade inclination angle on the through-feed centerless ground part are investigated in this study. As a result, it is found that there is a positive inclination angle of the work-rest blade for minimizing the tapering error of a ground workpiece.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.470-473
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• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power. Therefore, there has been and still is a growing concern (safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline. especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion, limitation of safety voltage and analysis of indiction voltage.

• Journal of The Korean Astronomical Society
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• v.45 no.5
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• pp.117-125
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• 2012

We present $^{12}CO$ J = 2-1 line observations of G54.1+0.3, a composite supernova remnant with a mid-infrared (MIR) loop surrounding the central pulsar wind nebula (PWN). We map an area of $12^{\prime}{\times}9^{\prime}$ around the PWN and its associated MIR loop. We confirm two velocity components that have been proposed to be possibly interacting with the PWN/MIR-loop; the +53 km $s^{-1}$ cloud, which appears in contact with the eastern boundary of the PWN and the +23 km $s^{-1}$ cloud, which has CO emission coincident with the MIR loop. However, we have not found a direct evidence for the interaction in either of these clouds. Instead, we detected an 5'-long arc-like cloud at +15-+23 km $s^{-1}$ with a systematic velocity gradient of ~3 km $s^{-1}$ $arcmin^{-1}$ and broad-line emitting CO gas with widths (FWHM) of ${\leq}7km\;s^{-1}$ in the western interior of the supernova remnant. We discuss their association with the supernova remnant.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1845-1850
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• 2003

The underground utility tunnels are important facility as a mainstay of country because of communication developments. The communication and electrical duct banks as well as various utility lines for urban life are installed in the underground utility tunnel systems. If a fire breaks out in this life-line tunnel, the function of the city will be discontinued and the huge damages are occurred. In order to improve the safety of life-line tunnel systems and the fire detection, the behaviors of the fire-induced smoke flow and temperature distribution are investigated. In this study we assumed that the fire is occurred at the contact or connection points of cable. Numerical calculations are carried out using different velocity of ventilation in utility tunnel. The fire source is modeled as a volumetric heat source. Three-dimensional flow and thermal characteristics in the underground tunnel are solved by means of FVM (Finite Volume Method) using SIMPLE algorithm and standard ${\kappa}-{\varepsilon}$ model for Reynolds stress terms. The numerical results of the fire-induced flow characteristics in an underground utility tunnel with different velocity of ventilation are graphically prepared and discussed.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.442-449
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• 2000

Before the complete construction of new high-speed line between Seoul and Pusan, KTX is going to operate on both new high-speed line between Seoul and Daegu and electrified conventional lines between Daegu and Pusan. Then, the wheels of KTX are going to operate on various rails such as KS50N and KS60 of conventional line as well as UIC60 of high-speed line. Also, conventional line will have a mixed traffic mode with various types of trains operating on it, such as Saemaul and Mugunghwa. Hence, this study reviews the wear phenomena of wheels and rails in geometrical point of view by comparing their profiles. The analyses of the results show that because UIC60 rail is designed for KTX, KS50N rail whose profile is similar to that of UIC60 will not have any impact on the shape of wheel wear. On the other hand, KS60 rail is expected to have partial wear on both the flange of KTX wheel and the gauge corner of the rail in the initial stages. However, the operation of the trains whose wheels have 1/20 conicity will cause partial sidewear on the inside of the rail and the movement of the contact point between KTX wheel and the rail toward the inside of the track. As a result, the flange wear of KTX wheel will be reduced and the formation of wear-equilibrium profile will be faster.

• Korean Institute of Interior Design Journal
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• v.24 no.2
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• pp.67-77
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• 2015

This study is to contemplate an ultimate goal and new methodology the architecture and space design community should pursue forward by analyzing concepts in Kengo Kuma's idea of "Anti-object" and examining his design methods and characteristics. To this end, I reviewed space design methods and features in his book of "Anti-Object" and his architectures built around in 2000. The result is as in the followings. (1) Contact is an essential concept of "Anti-object" to connect and integrate divided materials and consciousness with time and space. (2) Elimination is a meaningful way to reverse "cohesiveness" of agglomerated cluster which is a form of object and reconstruct it into the form of passive and acceptive "Anti-object". This idea is realized through overlap of material property and removal of massing. (3) Minimization is a concept of "Anti-object" to set the temporality free from constraints of materials. Three-dimensional transparent faces and lines or patterns of porous materials can be used to remove static and coercive volume. (4) A particle is a "reflector of its environment." It rebuilds one-way or disconnected communication between human and architecture into an interactive one. Kengo Kuma materializes this "particle" by exploring positional relation with physical paths, precise details and measurements.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.8
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• pp.75-81
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• 2014

It has been widely accepted that open phase may separate one of the power lines from power supply which is mainly caused by fuse melting, malfunction for source circuit breaker, contact failure, and disconnection under normal operating conditions, and is considered a kind of failure mode during disconnection of neutral wires as well. When open phase occurs, unequal voltage between phase might happen in the unbalanced load connected each phase, and further, depending on conditions of load, malfunction by providing low voltage. Moreover, load could be burned or overheated with overvoltage, which, in turn, can be a contributor to starting fires. Accordingly, in order to clearly overcome these problems, the current study aims to introduce the theory of uninterruptible power open phase compensation device, meaning that unbalanced power automatically restores balanced power and provides continuously the power supply without blackout, and verify it through simulation and experiments.