• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.400-407
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• 1995

A Abstract Buried contact solar cell is a very high efficiency silicon solar cell having over 19 % conversion effciency. In this paper, we investigated the process and characteristic of buried c contact solar cell. Manufacturing pro않sses of buried contact solar cell consist of three high temperature processes, one high vacuum deposition process, one laser application process and other wet chemical processes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.463-464
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• 2006

This paper present experimental results by non-contact mode Atomic Force Microscopy using high aspect ratio tips (HAR-T). We fabricated the carbon nanotube tip based on dielectrophoresis and the carbon nano probe by focused ion beam after dielectrophoretic assembling. In this paper, we measure AAO sample and trench structure to estimate HAR-T's performance and compared with conventional Si tip. We confirmed that results of HAR-T's performance in non contact mode was very superior than conventional tip.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.9
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• pp.663-670
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• 2003

As the micro-technologies in the high precision manufacturing processes are developed, the demand for micro actuating device is increasing. But, it is difficult to achieve high resolution and wide operating range simultaneously with the conventional actuating systems which are contacting and type of dual servo system. So, the contact-free surface actuators whose movers are suspended or levitated were proposed. These systems can be applied to high precision stages and alignment apparatuses. The suspended mover can be assumed to be rigid body, but the mover is a structure in this study, therefore the vibration caused during the operating process has a serious adverse effect on the performance and it is very important to identify the vibrational characteristics. In this paper, a contact-free surface actuator is modeled in finite element method and updated by using the experimental modal data. Finally, the static and dynamic characteristics of the finite element model are predicted and then discussed.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1483-1487
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• 2006

In electric railway, image monitoring using high speed camera provides reliable, timely information of wear and geometry status, important in taking decisions for overhead contact wire maintenance. The contribution of this research is the development of a simple real-time monitoring system for use in measurement subsystem of contact wire and geometry of overhead contact wire in electric railway. The system has been consists of a high speed CMOS camera with resolution $1024{\times}1280$ pixels, line type laser source and PC-based image acquisition system with PCI Express slot. Vision acquisition software have been used in application programming interface for image acquisition, display, and storage with a frequency of sampling of 500 acquisitions per second.

• Asia pacific journal of information systems
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• v.32 no.1
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• pp.51-69
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• 2022

This study examines how consumers' intention to use a curbside pickup responds to the COVID-19 vaccination rates. With our first survey conducted in March 2021, we find that a low (high) vaccination rate is associated with consumers' high (low) intention to maintain contact avoidance and their high (low) anticipation for shipping delays. Heightened contact avoidance and anticipation for shipping delays may encourage consumers to use a curbside pickup. Our results also show that when a product is needed immediately, and a consumer expects shipping delays, s/he is more likely to use a curbside pickup. However, with our second survey conducted in November 2021, we find heterogeneous consumer responses to the vaccination rates. Specifically, consumers' political affiliation moderates the relationship between the vaccination rates and their intention to maintain contact avoidance. The association between the vaccination rates and the anticipation for shipping delays is also weakened compared to March 2021. Our empirical results illustrate how consumers' intention to use a curbside pickup emerges and changes amid the COVID-19 pandemic.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.348-348
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• 2011

Carbon nanotube (CNT) field effect transistors and sensors use CNT as a current channel, of which the resistance varies with the gate voltage or upon molecule adsorption. Since the performance of CNT devices depends very much on the CNT/metal contact resistance, the CNT/electrode contact must be stable and the contact resistance must be small. Depending on the geometry of CNT/electrode contact, it can be categorized into the end-contact, embedded-contact (top-contact), and side-contact (bottom-contact). Because of difficulties in the sample preparation, the end-contact CNT device is seldom practiced. The embedded-contact in which CNT is embedded inside the electrode is desirable due to its rigidness and the low contact resistance. Fabrication of this structure is complicated, however, because each CNT has to be located under a high-resolution microscope and then the electrode is patterned by electron beam lithography. The side-contact is done by depositing CNT electrophoretically or by precipitating on the patterned electrode. Although this contact is fragile and the contact resistance is relatively high, the side-contact by far has been widely practiced because of its simple fabrication process. Here we introduce a simple method to embed CNT inside the electrode while taking advantage of the bottom-contact process. The idea is to utilize a eutectic material as an electrode, which melts at low temperature so that CNT is not damaged while annealing to melt the electrode to embed CNT. The lowering of CNT/Au contact resistance upon annealing at mild temperature has been reported, but the electrode in these studies did not melt and CNT laid on the surface of electrode even after annealing. In our experiment, we used a eutectic Au/Al film that melts at 250$^{\circ}C$. After depositing CNT on the electrode made of an Au/Al thin film, we annealed the sample at 250$^{\circ}C$ in air to induce eutectic melting. As a result, Au-Al alloy grains formed, under which the CNT was embedded to produce a rigid and low resistance contact. The embedded CNT contact was as strong as to tolerate the ultrasonic agitation for 90 s and the current-voltage measurement indicated that the contact resistance was lowered by a factor of 4. By performing standard fabrication process on this CNT-deposited substrate to add another pair of electrodes bridged by CNT in perpendicular direction, we could fabricate a CNT cross junction. Finally, we could conclude that the eutectic alloy electrode is valid for CNT sensors by examine the detection of Au ion which is spontaneously reduced to CNT surface. The device sustatined strong washing process and maintained its detection ability.

• Journal of Power Electronics
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• v.4 no.1
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• pp.12-17
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• 2004

In this paper, a practical implementation to reduce leakage flux of a high-frequency inverter based non-contact type power transformer composed of EE-shape ferrite cores is presented for key technology of the next generation medical use X-ray CT scanner system. Design consideration for the unique structure of the non-contact power transformer with 900mm in diameter is also introduced. The complete non-contact transformer is actually arranged by several blocks of the magnetic circuit assembled by using 10 small EE shape cores with 120mm in length. It is experimentally and analytically discussed from a reduced leakage flux viewpoint related to its inductively coupling coefficient. A practical method to lower the leakage flux is described based on effective Copper-Sheet- Treatment placed on EE shape ferrite cores of magnetic circuit.

• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.179-181
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• 2008

In this study, the dynamic characteristic of a contact wire and pantograph suppling electrical power to high-speed trains are investigated. The analysis of the loss of contact based on Power Simulator program software is performed to develop power line disturbance model suitable for high speed operation. It is confirmed that a contact wire and pantograph model are necessary for studying the dynamic behavior of the pantograph system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.5
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• pp.461-467
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• 2011

This study aims to create a numerical analysis model which can investigate the dynamic interaction between pantograph and overhead contact wire used for a high-speed railway vehicle, and validate the simulation results according to EN 50318 standard. Finite element analysis models of pantograph and overhead contact line are created using SAMCEF, a commercial FE analysis program. The mean, standard deviation, maximum and minimum values of contact forces are obtained. The simulation results are validated according to EN 50318, and the possibility of simulating the collecting characteristic of an actual pantograph system by using the developed model is discussed.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.447-451
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• 1998

This paper conducts a study on a non-contact power delivering system using high-frequency inverter with the purpose of discussing the non-contact electric power transmission characteristics through circuit analysis, magnetic analysis and feasible experiments. In this power delivering scheme, various properties pertaining to the non-contact transformer of the power system such as the design, the core depth, core material, primary side frequency etc. are considered with a view of improving the non-contact power dilivery to the secondary.