• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.1-7
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• 2012

Due to the increasing demand of network convergence, in future, hybrid/integrated satellite and terrestrial systems will play an important role. In that case, compatibilities between the satellite and terrestrial systems are very important for efficiency of the systems. 3GPP Long Term Evolution (LTE) is one of the 4G system. Therefore, in this paper, we introduce the design of interleaver for mobile satellite system based 3GPP LTE specification. The 4G system including the LTE specification adopted adaptive modulation and coding (AMC) schemes for efficient usage of resources, and the updating interval of resource allocation is an order of msec. However, because of the long round trip delay of satellite systems, we cannot employ the same AMC scheme specified for the terrestrial system, and thus it cannot effectively counteract to short term fadings. Therefore, in order to overcome these problems, we propose an interleaver scheme combined with AMC. We present the interleaver design results considering mobile satellite system based on the LTE and analyze the simulation results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.84-90
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• 2012

Since the major cellular data service providers in U.S, Japan as well as in Korea started the LTE (Long Term Evolution) service, there has been more strong need for the methods that can accurately measure the MIMO (Multi Input-Multi Outout) OTA (Over The Air) performance of LTE handsets because the performance of the MIMO antenna determines the packet data rates in the downlink and therefore the higher system throughput of the network. In this regard, there has been a lot discussions in 3GPP on the candidate MIMO OTA test solutions. In this paper, a faire comparison has been done for the conventional method, the Envelop Correlation Coefficient (ECC) measurements, and the anechoic chamber based MIMO OTA test solution, one of the candidate system being discussed in 3GPP. The evaluations and the comparisons are conducted by numerically and experimentally.

• The Journal of Society for e-Business Studies
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• v.6 no.3
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• pp.41-61
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• 2001

Many markets are forecast to see significant changes due to the growth of electronic commerce made possible by the internet. The way of doing business with internet affects the market mechanism. It is now over 10 years since Malone et al(1987) set out their hypothesis on electronic markets, and electronic hierarchies. An electronic market is an interorganizational information system through which multiple buyers and sellers interact to accomplish one or more of the following market-making activities. And they predicted that markets evolve toward electronic markets, by reducing search cost, which may result in significantly. higher price competition among sellers and therefore lower prices for buyers. And the degree of two factors; asset specificity and uncertainty, affect the market mechanism. Products with low asset specificity and low uncertainty are compatible with a market relationship while the greater the asset specificity and uncertainty, the more likely it is to favour a hierarchical structure. Based on the these researches, we observed and analyzed a case study of market mechanism in Internet business. We found the fact that even though Internet could make the business environment in which lots of buyers and suppliers participate, electronic market will evolve market mechanism. 1 analyzed two factors, which affected market evolution. First, When Asset specificity is low in electronic commerce, market structure should be preferred to hierarchical structure. Second, When transaction uncertainty is low in electronic commerce, market structure should be preferred In hierarchical structure. This research covers conceptual and empirical aspects on electronic market structure. Future research should be variously done about the influential factors of electronic market mechanism.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.661-672
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• 2005

For the efficient stochastic optimization of steel structures for which a large number of analyses is required, artificial neural networks,which have emerged as a powerful tool that could have been used to replace time-consuming procedures in many scientific or engineering applications, are applied. They are utilized for the solution of the equilibrium equations resulting from the application of the finite element method in connection with the reanalysis type of problem, for which a large number of finite element analyses are required in this study. As such, the use of artificial neural networks to predict finite element analysis outputs simplifies and facilitates the performance of the stochastic optimal design of structural systems where a trained neural network is used to replace the structural reanalysis phase. Moreover, to improve efficiency of used artificial neural networks, genetic algorithm is utilized. The stochastic optimizer used in this study is an algorithm based on the evolution theory. The efficiency of the proposed procedure is examined in problems with both volume (weight) functions and real-world cost functions

• Korean Institute of Interior Design Journal
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• v.22 no.3
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• pp.100-107
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• 2013

In smart era, concept of User experience has been an important issue both in academic and practical areas in recent years. Interactive space became one of the major design paradigms. For elevating the interactive effect, we need user?centered design methodology which uses the influential factors on the interactivity. As, well developed information technology made a lot of changes to various fields of our society, interactive space with the concept of HCI became a big issue in environmental design field. In this interactive space, various types of informative factors of the given space are sent using sensor and computer networking technology to the main system. So, a user's movement in the space in more than just a movement itself-user's movement now forms a important spatial structure that leads the narrative of the space. in this research, I will come up with the problems that the interactive space has right now, and analyze what the public space must have, and combine them with interactive space by HCI theory. architecture space is not the old space adapting digital technology. In order to take the role as new space paradigm. environment and technology, it has to develop technology continuously and experimental space at the same time. It must have co-evolution of architecture space field and others through organic network. by that, the evolution of space will be in the way that combines space which is responded to human emotion and user centric human friendly.

• Journal of Technology Innovation
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• v.24 no.4
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• pp.249-275
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• 2016

For the past 50 years, innovation field has gone through an evolution. The range of research topics on innovation has expanded and diversified, along with a quantitative increase. In a multi-disciplinary field like innovation, to explore new topics and understand research trends, it is necessary to possess a comprehensive understanding regarding the current status of, and trends in, the research. In this study, the research trend in innovation studies from 2000 to 2015 was analyzed in a holistic perspective. For this, a novel technique, text mining was used. The result shows that innovation studies has focused on the traditional and emerging topics. Also, the differentiations has appeared in some of the traditional topics. This study provides not only an understanding of research dynamics, but also an opportunity to gain insights into the evolution of a new paradigm from an academic perspective.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.155-164
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• 2017

The purpose of this study is to analyze the similarities and differences between motivation and usage according to morphological differences between Facebook and Instagram. The formative differentiation of third-generation SNS such as intuitive image and limited network poses the necessity of recognizing individual service users as distinct groups in SNS research. Therefore, this study was conducted to analyze the differences of motivation and usage, according to the motivation of using Facebook and Instagram by 255 university students. As a result, 7 factors were found as motivation for SNS use, and there were therein motivational differences between Facebook and Instagram users. This study is expected to contribute to the prediction of user's attitude change according to the morphological evolution of SNS in the future, and to expand the application to such related fusion research as GUI design and corporate PR marketing.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.695-702
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• 1994

Current study was undertaken to explain the structural evolution and corresponding changes in the properties of calcium aluminate glasses with the variation of SiO2 doping concentration. Calcium aluminate glasses in the compositional ranges of (100-x)(0.6CaO+0.4Al2O3)+xSiO2(where x=0~60) were fabricated. DTA analysis confirmed an anomalous behavior in glass transition temperature (Tg) with the maximum of 887$^{\circ}C$ and minimum of 859$^{\circ}C$ when x=5 and 50, respectively. densities and refractive indices monotonically decreased with increasing SiO2 content and IR transmitting cutoff shifted to shorter wavelength side when the amount of added SiO2 exceeded 5 mole%. IR fundamental vibration absorption peaks showed the change that NBOs were inclined to SiO4 tetrahedron in the low-silica region and NBO per SiO4 tetrahedra changed from 2 to 0 with increasing silica content. Based on the analysis of IR fundamental vibration absorption peaks, the model of the structural change can be proposed in three step: 1) SiO4 scavenged the NBOs located at AlO4-tetrahedra, which resulted in the increased of Tg values, 2) NBOs located in the main network again with a decrease in Tg, and 3) dominated by the decrease in the relative amount of NBOs in the glass system, where Tg re-increased.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.9
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• pp.783-789
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• 2015

This paper presents a Doherty power amplifier(DPA) operating in the 2.6 GHz band for long term evolution(LTE) systems. In order to achieve high efficiency, second and third harmonic impedances are controlled using a compact output matching network. The DPA was implemented using a gallium nitride high electron mobility transistor(GaN-HEMT) that has many advantages, such as high power density and high efficiency. The implemented DPA was measured using an LTE downlink signal with a 10 MHz bandwidth and 6.5 dB PAPR. The implemented DPA exhibited a gain of 13.1 dB, a power-added efficiency(PAE) of 57.6 %, and an ACLR of -25.7 dBc at an average output power of 33.4 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.7
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• pp.728-736
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• 2014

Due to the recent development of mobile wireless telecommunication, RRHs(Remote Radio Heads) are widely being utilized to expand the cell coverage. Wire-link, an existing connection between DU(Digital Unit) and RRH through fiber cables, is considered to have limitations in relation to cost for a wide range of applications. This paper focuses on replacing the wire-link by wireless transmission using millimeter-wave, and implementing cellular network system through RRH from a remote location. After an influence element analysis on millimeter-wave wireless link transmissions, a comparative analysis between wireless link and an existing fiber link method will be made by utilizing currently commercialized LTE(Long Term Evolution), to prove the compatibility of millimeter-wave wireless link RRH method in replacing fiber link method without a significant decline in data transmission performance.