• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.12
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• pp.1118-1123
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• 2008

High voltage multilayer ceramic capacitors (MLCCs) are classified into two classes-those for temperature compensation (class I) and high dielectric constant materials (class II). We manufactured high voltage MLCC with temperature coefficient characteristics of C0G and X7R and studied the characteristics of electric properties. Also we studied the characteristics of dielectric breakdown voltage (V) as the variation of thickness in the green sheet and how to pattern the internal electrodes. The dielectric breakdown by electric field was caused by defects in the dielectric materials and dielectric/electrode interface, so the dielectric thickness increased, the withstanding voltage per unit (E) thickness decreased. To overcome this problem, we selected the special design like as floating electrode and this design affected the increasing breakdown voltage(V) and realized the constant withstanding voltage per unit thickness(E). From these results, high voltage application of MLCCs can be expanded and the rated voltage can also be develop.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.175-182
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• 2013

Lately, customers think highly of the emotional satisfaction and as a result, issues on odor are matters of concern. The cases are odor of interior material and air-conditioner of vehicles. In particualar, with respect to the odor of air-conditioner, customers strongly claimed defects with provocative comments : "It smells like something rotten," "It smells like a foot odor," "It stinks like a rag." Generally, it is known that mold of evaporator core in the air-conditioning system decays and this produce VOCs which causes the odor to occur. In this study, partial least squares regression model is applied to predict the strength of the odor and select of important VOCs which affect car air conditioning smell. The PLS method is basically a particular multilinear regression algorithm which can handle correlated inputs and limited data. The number of latent variable is determined by the point which is stabilized mean absolute deviations of VOCs data. Also multiple linear regression is carried out to confirm the validity of PLS method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1715-1720
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• 2011

Studies suggested an increase in the competitiveness and roles of mainline railways like speed and accessibility improvement, as a fundamental direction of the National Transport Network Plan. At this point, topics presented especially for strengthening the role of human and environment centered transportation: as to the greatly improved speed competitiveness, there are an operational speed above 180km/h ~ 200km/h and traveling within 2 ~ 3 hours among big cities. As to accessibility improvement, there are accessibility to main railway stations within 30 minutes, and the improvement of accessibility, safety, eco-friendliness, amenity etc. As a part of these suggestions, field specific plans were proposed for the establishment of expressed mainline railway network in Korea such as train's, civil structures, trolley lines etc. In this paper we analyzed the conventional lines and systems to figure out whether to change details in terms of H/W of signaling system. Additionally, we reviewed the compatibility or difference of signalling system depending on train's speed. With this result, we deduced the number of virtual blocks specific to the speed of 180km/h, 200km/h and 230km/h, which were showed for the speed improvement considering each variable like blocks, braking distance etc. In this way, we suggested the railway signal system establishment plan considering safety operation.

• The KIPS Transactions:PartC
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• v.12C no.1 s.97
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• pp.97-104
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• 2005

One of the problems of the currently used IPv4 addressing-structure is the fact that there is a shortage of IP addresses and many addresses are being wasted, especially on sub-netting design. The variable subnet masking is a resolution to reduce IP address wasting. We propose an effective subnet W address calculation and management method on VLSM. Also, with the proposed subnet IP address management method, a web based subnet allocation and management system is introduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.824-832
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• 2010

In construction structure management, the effects of investigation by the professional manager is dependent on the cost, the inspection periods and methods. Therefore, effective and automated maintenance system for the target structure is required. Although some bridge monitoring systems are operating using wire based networks, the performance is not good enough to show sufficient ability as integrated bridge management system. In this paper, we design and implement an integrated bridge management system based on sensor networks. Two expert modules for bridge management and the integrated system management are provided. Moreover, web-based monitoring system is also designed for users at anywhere. The results show that the system is effective and readily available.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.207-212
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• 2003

The field emission and luminescent properties of carbon nanotubes (CNTs) that were straightened out by argon ion irradiation were investigated. Argon ion irradiation permanently straightened out both as-grown and screen-printed CNTs in the presence of a strong electric field. The straightening process enhanced the emission properties of CNT films by showing a decrease in turn-on field, an increase in total emission current, and a stable emission. Furthermore, the number of emission sites was confirmed to increase by observing the luminescent properties of CNT films after the straightening. The mechanism involved in the straightening of the CNTs is proposed and the enhancement in field emission is discussed in detail.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.617-621
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• 2016

In addition to the energy storage facilities based on high power technologies, Electric double layer capacitors(EDLC) are today's candidate for power quality stabilization. However, its low energy density is often inhibiting factor for application of electric power industry. Hybrid supercapacitor is an promising energy storage device that positioned between conventional EDLC and Li-ion battery. This paper describes the preparation and characteristics of a hybrid supercapacitor and module for power quality stabilization. A cylindrical 3200F hybrid supercapacitor ($60{\times}74.5mm$) was assembled by using the $Li_4Ti_5O_{12}$ electrode as an anode and activated carbon as a cathode. It shows 2.5 times higher energy density than conventional EDLC with the same volume. In order to determine the characteristics of the hybrid supercapacitor Module for uninterruptible power supply (UPS), hybrid supercapacitor cells were connected in series with active balancing circuit. At even the high current density of 14A(10C), Module prepared by 18 cells showed the capacitance of 170F at 30~50V, suggesting the applicability for UPS.

• Journal of the Korea Society of Computer and Information
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• v.22 no.8
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• pp.63-72
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• 2017

In this paper, we propose a security architecture for HDLC-based T4 class common data link. The common data links are composed of point-to-point, multi-to-point, and point-to-multi mode. For multi-to-point mode, one node has a bundle of point-to-point links with different end-point on the other side of the links. Thus multi-to-point mode can be considered as a bundle of point-to-point mode. Point-to-multi mode is broadcasting link. For point-to-point mode we adopted robust security network scheme to establish a secure data link, and for multi-to-point mode we use broadcast encryption scheme based on ID-based cryptography to distribute encryption key for broadcasting message encryption. We also included MACsec technology for point-to-point data link security. Computational and communicational complexity analysis on the broadcast encryption have been done.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.1
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• pp.27-38
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• 2016

The purpose of this study is to investigate the influence of moving mass on the vibration characteristics and the dynamic response of the simply supported beam. The three types of the moving mass(moving load, unsprung mass, and sprung mass) are applied to the vehicle-bridge interaction analysis. The numerical analyses are then conducted to evaluate the effect of the mass, spring and damper properties of the moving mass on natural frequencies and dynamic responses of the simply supported beam. Particularly, in the case of the sprung mass, variations of the natural frequency of simply supported beam are explored depending on the position of the moving mass and the frequency ratio of the moving mass and the beam. Finally the parametric studies on the resonance phenomena are performed with changing mass, spring and damper parameters through the dynamic interaction analyses.

• Journal of Ocean Engineering and Technology
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• v.29 no.5
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• pp.373-379
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• 2015

Side Scan Sonar (SSS) is capable of acquiring real-time data for seabed scouring, bathymetry, mine countermeasurement, etc. In a shipyard, an SSS package is utilized to measure the water depth and find debris in the sea because a sufficient water depth and non-interruption have to be ensured before implementing an underwater installation such as a large thruster. This paper presents the application and operation method of an SSS for the construction of an offshore project.