• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.4
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• pp.409-412
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• 2002

The LNA(Low Noise Amplifier) is designed for use in low cost commercial application covered fully IMT-2000 band(1920~2170MHz, BW=250MHz). It is optimized source inductance for source lead and designed to equivalent etched line. The LNA uses a high pass impedance matching network for noise match and simple structure. The bias circuit designs have been made self-biased with a negative voltage applied to gate. The power supply voltage is 8V, total current is 180mA. The LNA is biased at a Vgs of -0.4, Vds of 4V for first stage and Vds of 5V for second stage. The LNA is designed competitively for commercial product specification. The measured gain and noise figure of the completed amplifier was 20dB and 1dB, respectively. Also, input VSWR, P1dB and gain flatness was measured of 1.14 ~ l.3dB, 22.4dBm and $\pm$0.45dB, respectively. The designed LNA can be used for commercial product.

• Journal of the Korean Society for Library and Information Science
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• v.49 no.1
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• pp.465-482
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• 2015

This study is a qualitative study on the workplace experience of electronic resource acquisition librarian in university libraries. The purpose of this study is to examine the meaning of their task and roles, new change of their role. For this study, we conducted in-depth interviews with 9 electronic resource acquisition librarian in academic libraries and applied phenomenological research method. As result of analysis, 3 catagories were appeared from 11 themes as data analysis. These catagories were characterized as follows: 'coping with structural problems of the real obstacles', 'enduring of psychological pressure', and 'growing as professional with competency'. It is expected to further study on competency for electronic resource acquisition librarian.

• Journal of Life Science
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• v.18 no.11
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• pp.1479-1484
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• 2008

Deep seawater (DSW) refers to water extracted from the ocean, usually at depths of 200 meters or more, which is rich in inorganic materials and has attracted attention for various applications. We investigated the effects of the DSW on the synaptic maturation of cultured rat hippocampal neurons. Immunocytochemical examination of DIV21 showed that PSD-95, $\alpha$CaMKII, and synGAP$\alpha1$clusters were strengthened and coupling rates of SV2 and NR2B were significantly increased in neurons grown in the presence of H-800 and H-1000 DSW. Our results indicate that DSW promotes the formation of excitatory postsynaptic signal transduction complexes NRC/MASC and functional synapses.

• The Journal of the Acoustical Society of Korea
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• v.15 no.5
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• pp.82-89
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• 1996

Application fields of ultrasonic transducers can be divided into two categories, a high ultrasonic resolution required field and a high ultrasonic power required field. This paper is aimed to determine the optimal properties of the matching layers of the transducer for each of the applications. Further, it is aimed to optimize the properties of the matching layers that show satisfactory performances for both of the application fields. Through the direct time domain analysis of the transmission and reflection behavior of the ultrasonic wave, apart from the conventional equivalent circuit analysis, and Fourier transformation of its results, we found the optimum acoustic impedances of the matching layers. The newly determined layers provide much better transducer performance-57% at most-than those obtained with conventional design methods. Based on the results, we also found the optimal acoustic impedances of the layers good for both of the application fields. For te optimization, we developed a new transducer performance evaluation parameter that can be applied to any type of ultrasonic transducers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.1-9
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• 2012

In this paper, we presents the modeling and implementation of the DDS(Direct Digital synthesizer) driven offset PLL(Pghase Locked Loop) with DAC(Digital Analog Converter) for coarse tune. The PLL synthesizer was designed for minimizing the size and offset frequency and DDS technique was used for ultra low noise and fast lock up time, also DAC was used for coarse tune. The output phase noise was analyzed by superposition theory with the phase noise transfer function and noise source modeling. the phase noise prediction was evaluated by comparing with the measured data. The designed synthesizer has ultra fast lock time within 6 usec and ultra low phase noise performance of -120 dBc/Hz at 10KHz offset frequency.

• Geophysics and Geophysical Exploration
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• v.20 no.3
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• pp.129-136
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• 2017

3D seismic data processing methods such as full waveform inversion or reverse-time migration require 3D wave propagation modeling and heavy calculations. We compared efficiency and accuracy of a Xeon Phi coprocessor to those of a high-end server CPU using 3D frequency-domain wave propagation modeling. We adopted the OpenMP parallel programming to the time-domain finite difference algorithm by considering the characteristics of the Xeon Phi coprocessors. We applied the Fourier transform using a running-integration to obtain the frequency-domain wavefield. A numerical test on frequency-domain wavefield modeling was performed using the 3D SEG/EAGE salt velocity model. Consequently, we could obtain an accurate frequency-domain wavefield and attain a 1.44x speedup using the Xeon Phi coprocessor compared to the CPU.

• Applied Chemistry for Engineering
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• v.5 no.1
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• pp.63-73
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• 1994

Weight loss accelerating agents, TDACW and TTAMW were prepared by adding water to n-tetradecyldimethylbenzylammonium chloride(TDAC) and n-tetradecyltrimethylammonium methyl sulfate(TTAM) synthesized in our lab. On weight loss finishing of PET fiber with NaOH and TDACW or TTAMW, TDACW showed much more weight loss than TTAMW. Optimum concentration was about $8g/{\ell}$, treatment time 60~90min and treatment bath ratio 1:40~1:50. Density and crystallinity increased with weight loss and tensile strength decreased with weight loss. From the reaction mechanism of weight loss accelerating agent and PET fiber, weight loss accelerating agent was proved to function as a catalyst and the surface structures of PET fibers treated with weight loss accelerating agent were characterized with SEM.

• Journal of Science and Technology Studies
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• v.15 no.1
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• pp.245-279
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• 2015

The new innovation model that deals with agenda as sustainability, quality of life, societal challenges is emerging as NIS(National Innovation System) is needed to transit to post catch-up and creativity. To achieve this objective, there is a growing need for enhancing usage of ICT, end-user's needs, prolification of R&D results and social impact. Living Lab is the new innovation model that end-user's participation, co-work/network within actors and usage of user's experience and This study deal with Living Lab related R&D of ICT-based service from co-work with end-users. Example cases are Turku Archipelago Living Lab in Finland, and Living Lab projects in EU, EIT ICT Labs and ELLIOT. And the focus of case analysis is that reflection of user's needs and experience, and aspect of ICT usage.

• Information Systems Review
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• v.17 no.1
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• pp.199-215
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• 2015

Supply chain integration is the degree to which a firm strategically collaborates with its supply chain partners. We study the relationship between supply chain integration and corporate performance and the role of information sharing between them. When the information sharing is used as a mediating factor between supply chain integration and performance, supply chain integration should be focused to enhance the performance because of their causal relationship among them. On the contrary, when the information sharing is used as a moderating factor, situational approach to improve performance is needed. This study collected 199 questionnaires from the manufacturing companies and used Amos 21 to analyze the measurement model and structural model. The study found that supply chain integration positively influences corporate performance and information sharing acts as a mediating variable between supply chain integration and corporate performance. Therefore the firm should pay additional attention on supply chain integration to improve the corporate performance.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.6
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• pp.457-473
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• 1992

The first order wave equation over a double shelf has wind stresses on both coastal boundaries and wind stress curl forcing across the shelf. In the Yellow Sea, the effect of wind stress curl can be neglected as a forcing of shelf waves. The decay distance of Kelvin waves is much greater than that of continental shelf waves so that Kelvin waves are transmitted nearly intact through the northern embayment. The numerical method of characteristics has been modified to accomodate wave propagation of opposite directions. Using a little more realistic coastline, the wave model hindcast has been improved for current velocity, but hardly for sea level. It means that Kelvin waves, which mainly determine sea levels, are affected little by the change of bottom slope. For a better hindcast of sea level, input energy of Kelvin waves transmitted from the East China Sea is needed. The basic structure of downwind flows along the coasts and upwind flows along the trough supports the seasonal circulations driven by monsoon winds in the Yellow Sea.