• Journal of the Korean Ceramic Society
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• v.43 no.11 s.294
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• pp.688-692
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• 2006

Ferroelectric lanthanides-substituted $Bi_4Ti_3O_{12}$ $(Bi_{4-x}Ln_xTi_3O_{12}, BLnT)$ thin films approximately 200 nm in thickness were deposited by metal organic chemical vapor deposition onto Pt(111)/Ti/SiO$_2$/Si(100) substrates. Many researchers reported that the lanthanides substitution for Bi in the pseudo-perovskite layer caused the distortion of TiO$_6$ octahedron in the a-b plane accompanied with a shift of the octahedron along the a-axis. In this study, the effect of lanthanides (Ln=Pr, Eu, Gd, Dy)-substitution and crystallization temperature on their ferroelectric properties of bismuth titanate $(Bi_4Ti_3O_{12}, BIT)$ thin films were investigated. As BLnT thin films were substituted to lanthanide elements (Pr, Eu, Gd, Dy) with a smaller ionic radius, the remnant polarization (2P$_r$) values had a tendency to increase and made an exception of the Eu-substituted case because $Bi_{4-x}Eu_xTi_3O_{12}$ (BET) thin films had the smaller grain sizes than the others. In this study, we confirmed that better ferroelectric properties can be expected for films composed of larger grains in bismuth layered peroskite materials. The crystallinity of the thin films was improved and the average grain size increased as the crystallization temperature,increased from 600 to 720$^{\circ}C$. Moreover, the BLnT thin film capacitor is characterized by well-saturated polarization-electric field (P-E) curves with an increase in annealing temperature. The BLnT thin films exhibited no significant degradation of switching charge for at least up to $1.0\times10^{11}$ switching cycles at a frequency of 1 MHz. From these results, we can suggest that the BLnT thin films are the suitable dielectric materials for ferroelectric random access memory applications.

• Journal of Korean Philosophical Society
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• v.131
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• pp.273-301
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• 2014

This study aims to reconstruct Leibniz's theodicy. Theodicy is to defense of the highest wisdom of the creator against the charge which reason brings against it for whatever is the evil in the world. For this defense, Leibniz created his own new kind of concepts: the principle of sufficient reason, the principle of perfection, the best of all possible worlds, moral necessity. Leibniz's theodicy is developed as following. Most good and wisest God created this world freely by moral necessity. God's will was to choose the goods antecedently. But God's will could not create goods only. For God's final purpose is to create the best. For this reason, it happens that the evils may come about by concomitance, and as a result of other greater goods. Therefore the evils are necessary in the world. And evil consists in imperfection. Man has free will as God. Freedom, according to Leibniz, consists in intelligence, which involves a clear knowledge of the object of deliberation. Man has freedom, but man's freedom is imperfect. Evil is originated in man's imperfect freedom.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.109-116
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• 2014

In recent, ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart phone, notebook computer, printer and portable multimedia devices. Accordingly, studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi device using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band causes serious network performance deterioration of wireless sensor networks. This paper examined a method of identifying channel status to avoid interference among wireless communication devices using IEEE 802.11b (Wi-Fi) and other ISM bands during communication among IEEE 802.15.4 based wireless sensor network nodes in ISM band. To identify channels occupied by Wi-Fi traffic, various studies are being conducted that use the RSSI (Received Signal Strength Indicator) value of interference signal obtained through ED (Energy Detection) feature that is one of IEEE 802.15.4 transmitter characteristics. This paper examines an algorithm that identifies the possibility of using more accurate channel by mixing utilization of interference signal and RSSI mean value of interference signal by wireless sensor network nodes. In addition, it verifies such algorithm by using OPNET Network verification simulator.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2219_2220
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• 2009

The characteristics of the Superconducting Magnetic Energy Storage (SMES) system are faster response, longer life time, more economical, and environment friendly than other Uninterruptible Power Supply (UPS) using battery. Fast charge and discharge time of SMES system can provide powerful performance of improving power quality in the grid. In order to demonstrate the effectiveness of SMES, the authors make a 10kJ SMES system for connection with RTDS (Real Time Digital Simulator). Because the characteristics of superconducting magnet are very important in SMES system, the necessary items such as thermal characteristic, mechanical stress and protection circuit should be considered. In this paper, the authors experimented thermal characteristics of the 10kJ SMES system. The experiment was accomplished using a simulation coils made of aluminium. It has same dimension of the 10kJ class HTS SMES coil. The coil was cooled with GM (Gifford -McMahon) cryocooler through the OFHC (Oxgen Free High thermal Conductivity) conduction bar. The test results of cool down and heat loads characteristics of the simulation coils are described in detail.

• Journal of Navigation and Port Research
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• v.30 no.3 s.109
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• pp.247-251
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• 2006

By becoming 21st century which run be charactered as highly industrialized society which spreads diversification and individualization, there have been elevation of income level and increase of time for leisure activity by introducing 5 working days system. And this brings out increasing of aquatic leisure activity population and the contents of the leisure becomes very active. Static indoor activity which was the main current of the leisure activity in the past, however, it is now called for outdoor activity accompanied by the society growth and even expands towards that people get into action and experience by their own free will. With this point of view, the aquatic leisure run become a safe activity. But with a rapid growth of aquatic leisure activity, safety concerns become a serious problem. To prevent safety accident, training should be given, safety inspection and registration should be requested, and strong support of system is needed so users can have an insurance for safety accident. These complements are necessary for overall nourishment and management measure to charge in systematical safety for the users.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.10-21
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• 1993

The transport phenomena of ten amino acid molecules through poly(2-hydroxyethyl methacrylate), P(HEMA) membrane have been investigated in various range pH solutions. It is found that the permeability and diffusivity of the amino acids through membrane depended on the different shape, size and the charge of them are changed by the pH. The permeabilities and diffusivities of amino acids have the largest value in the neutral solution. In this case, they are diffused through free water in the P(HEMA) membrane and the diffusion mechanism is the pore type. The basic solution have larger value than the acidic it. Whether the diffusion mechanism of the core type or the partition type, it is depended on the effect of side chain of the amino acid in basic and acidic solution.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.4
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• pp.124-132
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• 2023

In order to support start-ups effectively with limited resources, it is necessary to provide support tailored to start-up companies. Businesses that are operating in local incubation centers may have different demands for the support depending on the region characteristics. This study was worked on companies that have entered into the incubation center 'Youth Cube', which is operated by Ansan City. We investigated the perception of importance in the field of support to identify support policy priorities, and the satisfaction level of each field of support currently supported. Then We conducted an IPA analysis to derive the direction of support. The Ansan area has regional characteristics that it is located in the metropolitan area with well-equipped start-up infrastructure and many innovative institutions, As a result of the importance survey, technology commercialization was recognized as the most important, and education/mentoring was recognized as the least important. Satisfaction with the space and facilities that can be used free of charge was the highest, and the satisfaction was the lowest for entrepreneurship education/mentoring, as was the degree of importance. In addition, according to each quadrant, we derived support that should be maintained, support that should be intensively improved, support that should be given a low policy priority, and support directions that should be kept in mind to avoid excessive support.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.976-979
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• 2002

A focusing grating coupler (FGC) was not fabricated by the 'Continuous Path Control' writing strategy but by an electron-beam lithography system of more general exposure mode, which matches not only the address grid with the grating period but also an integer multiple of the address grid resolution (5 nm), To more simplify the fabrication, we are able to reduce a process step without large decrease of pattern quality by excluding a conducting material or layer such as metal (Al, Cr, Au), which are deposited on top or bottom of an e-beam resist to prevent charge build-up during e-beam exposure. A grating pitch period and an aperture feature size of the FGC designed and fabricated by e-beam lithography and reactive ion etching were ranged over 384.3 nm to 448.2 nm, and $0.5{\times}0.5mm^2$ area, respectively, This fabrication method presented will reduce processing time and improve the grating quality by means of a consideration of the address grid resolpution, grating direction, pitch size and shapes when exposing. Here our investigations concentrate on the design and efficient fabrication results of the FGC for coupling from slab waveguide to a spot in free space.

• Journal of the Korean Society of Radiology
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• v.10 no.1
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• pp.59-64
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• 2016

The purpose of this study intend to develop the automatic voice system for language communicating over foreign patients in testing of magnetic resonance imaging. Used sentences for the automatic voice system was selected with twelve sentences and five foreign languages in hospital in use. These translated texts were provided free of charge from Oddcast's website, which is recorded each language-specific voice as Wav files, The recorded audio file were produced by the two types of a power-point show of MS-office 2013(extension; ppsx) form and Web-enabled system using the PHP program to be applied in the mobile phone environment. It is considered to relieve the stress about an language barrier to medical technician and the voice system designed with the variable language will be enhanced the diagnostic information on foreign patients. Because automatic voice system designed for this study can enhance the understanding of test in between korean medical technician and foreign patients, It will be expected to utilize more usefully in clinical practice.

• Journal of Digital Contents Society
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• v.19 no.7
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• pp.1237-1244
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• 2018

Currently the bottleneck in virtual reality's commercialization might be that high cost VR equipment is needed and interesting VR contents are not enough. The purpose of this paper is to solve these problems by implementing low-cost VR system with wireless controller and HMD(Head Mounted Display) using a smart phone and PC. The functions of real HMD are simulated by utilizing the display and embedded sensors of a smart phone. In that situation PC is in charge of processing huge data and is communicated with smart phone. And wireless controller is designed to make VR user's movement to be free. In addition, we made the several VR contents for testing our prototype system directly. Easy access to VR equipment could induce increasing number of users and investment. And it will be a big step toward improving VR technology and its commercialization.