• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.475-483
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• 2007

Recently, consumers demand high-quality wireless multimedia services via terrestrial and satellite network. And the interest for new services to sustain its successful commercial deployment grows tremendously. So, the MIMO schemes, such as STCs, MRC, has been used for realizing high reliability. However, MIMO schemes has some limitations. MIMO scheme needs more size, cost, and hardware complexity to employ additional antennas. Moreover, sufficient spaces between antennas are required to guarantee the independence of each channel and the devices which use multiple antennas should be enlarged. A cooperative transmission technique which is detect and forward type applying virtual MIMO with STBC matrix in DVB-RCT(Digital Video Broadcasting with Return Channel via Terrestrial) system based on OFDMA is also proposed.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1131-1136
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• 2020

Xenon behaves differently in molten salt reactors (MSRs) compared to solid fuel reactors. This behavior needs exploring due to the large reactivity effect of the ¹³⁵Xe isotope, given the current interest in MSR power plant development for commercial deployment. This paper focuses on select topics in xenon transport, reviews relevant past works, and proposes specific research questions to advance the state of the art in each of the focus areas. Specifically, the paper discusses the issue of xenon solubility in MSRs, the behavior of particulates circulating in MSR fuel salt and its influence on the xenon transport, the possibility of ionization of xenon atoms which changes its effective size and thus affects its mass transport, and finally the issue of circulating void fraction and how it is measured. This work presents specific recommendations for MSR designers to research the limits of Henry's law validity, circulating particulate scrubbers, validity of mass transport coefficients in high radiation fields, and the effects of pump speed on circulating void fraction.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.264-273
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• 2005

Broadband power line communications have been receiving tremendous interest In recent years because this technology enables utilities to deploy a communication network over existing power line infrastructures. Despite the enormous potential, there is some skepticism about the technology and its commercial viability. In this paper, we investigate the performance characteristic of PLC through field test carried out in actual households. Also it addresses major field deployment aspects, such as range, coverage, the number of node for operation and maintenance.

• Publications of The Korean Astronomical Society
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• v.19 no.1
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• pp.129-133
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• 2004

In the past, radio astronomers have sought isolation from man-made signals by placing their telescopes in remote locations. These measures may no longer safeguard scientific observations, since NGSO satellite systems, particularly low-Earth orbit (LEO) systems, are usually designed to provide global or wide regional coverage. Further, radio astronomers have historically made their observations in the frequency bands allocated for their use by the member countries of the International Telecommunication Union (ITU). The science of radio astronomy could be adversely impacted by the deployment of large constellations of new non-geostationary orbiting (NGSO) satellites for telecommunications, navigation and Earth observation, and the proliferation of new, high-power broadcasting and telecommunication satellites in geostationary (GSO) orbits. Radio telescopes are extremely sensitive, and, in certain situations, signals from satellites can overwhelm the signals from astronomical sources. This paper describes the problem in detail and identifies ways to mitigate it without adversely affecting the continued vigorous growth of commercial space-based telecommunications.

• Journal of Information Technology Services
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• v.11 no.sup
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• pp.17-26
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• 2012

Information technology convergence has been recognized one of the key drivers in the industry perspective. Korea government established IT convergence policy in 2008 and has been implementing it to the core industry such as automotive, shipbuilding and defense industries. This research analyzes various IT convergence issues based on an operation of defense IT convergence center, one of the industry IT convergence centers. Defense IT convergence issues are as follows : the methods for introducing rapid changing IT to military area, rapid deployment procedures of verified commercial technologies and products, regulations for using of domestic software promotion and so on. We define the concept of defense IT convergence and propose the framework and processes for applying IT to our defense sector as one of industries. Also, we establish various business models in the military perspective using defense IT convergence framework. In this paper, we focus the development of defense IT convergence through the alignment of national IT convergence policy and propose various business models established through operating a defense IT convergence center.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.257-268
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• 2015

Characteristics of delta-V requirements for deploying an impactor from a mother-ship at different orbital altitudes are analyzed in order to prepare for a future lunar CubeSat impactor mission. A mother-ship is assumed to be orbiting the moon with a circular orbit at a 90 deg inclination and having 50, 100, 150, 200 km altitudes. Critical design parameters that are directly related to the success of the impactor mission are also analyzed including deploy directions, CubeSat flight time, impact velocity, and associated impact angles. Based on derived delta-V requirements, required thruster burn time and fuel mass are analyzed by adapting four different miniaturized commercial onboard thrusters currently developed for CubeSat applications. As a result, CubeSat impact trajectories as well as thruster burn characteristics deployed at different orbital altitudes are found to satisfy the mission objectives. It is concluded that thrust burn time should considered as the more critical design parameter than the required fuel mass when deducing the onboard propulsion system requirements. Results provided through this work will be helpful in further detailed system definition and design activities for future lunar missions with a CubeSat-based payload.

• Journal of Plant Biotechnology
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• v.4 no.1
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• pp.1-6
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• 2002

Plants have developed a sophisticated battery of defence responses to protect themselves against attempted pathogen ingress. Manipulation of these defence mechanisms may provide significant opportunities for crop improvement. While plant resistance genes have had a long service history in plant breeding, they possess significant limitations. Recent advances are now providing significant insights into strategies designed to increase the field durability of this class of genes. Hypersensitive cell death is a common feature underlying the deployment of plant defence responses against biographic pathogens. In contrast, necrotrophic pathogens actively kill plant cells. Recently, transgenic plants have been developed that either promote or suppress cell death, providing resistance against either biotrophic or necrotrophic pathogens respectively. Methyl-jasmonate is a key signalling molecule in the establishment of resistance against some fungal pathogens. Increasing the concentration of this molecule in plant cells has been shown to increase resistance against Botrytis cineria, without significantly imparting plant growth or development. Due to the multifarious infection strategies employed by plant pathogens, how-ever, it is unlikely a single commercial product will prove a panacea for global disease control. Future stategies will more likely entail an integrated disease management approach.

• Korea Journal of Hospital Management
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• v.20 no.3
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• pp.24-35
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• 2015

This paper attempts to critically review the status of supply chain operations in the healthcare field in an attempt to address what has been done in academics as well as the practitioner's field to gain insight where future research efforts should be addressed. Based on literature set through review on previous studies, literature published within the past 10 years will be reviewed. The purpose of the study can be summarized as follows. First, overviews of healthcare SCM. Second, comparative studies on commercial SCM and healthcare SCM. Third, major tools in SCM. Finally, the barriers of adopting healthcare SCM. The findings of this study reveals potential benefits from using supply chain management tools. Although research and case studies in healthcare industries are not as extensive as in other industries, a clear trend appears to be forming in that deployment of supply chain management indeed generates consumer and provider's surplus from which the entire society would benefit.

• Current Photovoltaic Research
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• v.1 no.1
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• pp.1-10
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• 2013

The photovoltaic (PV) industry, which occupies about 80% share of domestic new and renewable energy (NRE) sales, has played an important role in the development of the Korean NRE industry. This was made possible by the government's implementation of the 3rd Basic New and Renewable Energy Plan, which promoted strategic PV R&D, infrastructure building, and a variety of PV deployment programs. For instance, 'One Million Green Homes', 'Feed in Tariff', and 'Renewable Portfolio Standards' programs contributed greatly to the dissemination of PV systems in the country. Furthermore, these programs were supported with more than 380 billion Won over 6 year period (2007~2012). The strategic PV R&D contributed to the fast follow-up in commercial technologies. Because of the recent, sharp decline in PV prices caused by oversupply and economic crisis in European countries, both foreign and domestic PV companies are going through painful restructuring. Under these circumstances, the Korean PV industry needs to find a new strategy for making a breakthrough, and in this sense a proactive role of the Korean government is desperately needed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.191-197
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• 2017

According to the ubiquitous usage of smartphone, so many smartphone applications have been developed, and especially data communications and position measurement technologies without additional equipments have been developed using acoustic signal. But there is a limitation to select the frequency of the acoustic signal due to the smartphone hardware, and there is non-linearity in the electronic circuits in a sound generation devices, the audible sound generated from the speaker is not avoidable. And it causes critical difficulty to the commercial system deployment. In this paper, a simulation technique to calculate the power of the audible acoustic signal by human is applied to several types of acoustic signals to evaluate the loudness. These could be referred when the acoustic communications or positioning systems are designed, for the purposed of inaudible sounding to human.