• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.62-70
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• 2010

In this paper, we evaluate the performance of various diversity techniques which can contribute to provide efficient multimedia broadcasting services via hybrid/integrated satellite and terrestrial network. Space-time coding (STC) can achieve the diversity gain in a multi-path environment without additional bandwidth requirement. Recent study results reported that satellite systems can achieve high diversity gains by appropriate utilization of STC and/or forward error correction schemes. Based on these previous study results, we present various cooperative diversity techniques by combining STC and rate compatible turbo codes in order to realize the transmit diversity for the mobile satellite system. The satellite and several terrestrial repeaters operate in unison to send the encoded signals, so that receiver may realize diversity gain. The results demonstrated in this paper can be utilized in future system implementation.

• The Journal of Sustainable Design and Educational Environment Research
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• v.14 no.1
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• pp.10-21
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• 2015

Due to the impact of birth rate, the school age population decreases year by year, and as a result, the Ministry of Education conducts the layout adjustment for middle and primary schools and cancels substantial rural schools. Nearly half of the cancelled and idle schools are not applied till now. Combining the practical demand of local residents, it is quite necessary to make use of the idle schools effectively again. Consequently, field investigation is conducted for the architectural status of 28 idle schools in Pingle County of Guilin, Guangxi, and detail investigation and analysis has been carried out for the different scales of schools from various aspects, including the covered area, traffic, building construction, space composition, degree of aging, etc. The investigation result shows that small teaching schools are remote, being small in scale, single in space and serious in aging. Complete primary schools are close to the villages and towns, being large in scale, abundant in space, and well preserved. The teaching schools are between the previous two types. Meanwhile, it is generally convenient in traffic, and good in structure. It can provide fundamental data for the future utilization and study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.851-860
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• 2013

To overcome a scarcity of radio resources to mobile broadband service, the usage of TV white space gains much attraction around the world. This paper carries out an interference analysis either by performing realistic experiments or by executing statistical Monte-Carlo simulation to exploit interference probability. The results obtained from experiments are compared to those from simulations in order to clarify the coexistence of utilization of TV band devices (TVBD) in indoor circumstances. Along the execution of our experiment in the presence of DTV receiver, we apply to a variety of transmission parameters proposed in FCC for TVBD. According to experimental and simulation works, the allowable transmission powers of TVBD systems are exploited for the plausible which are coexist on the first as well as the second adjacent frequency bands. Throughout results, it can conclude that TVBD systems can be coexisted via achieving proper transmission powers depending on the locations of themselves without showing harmful interference to DTV reception.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.343-346
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• 2010

Urban environment for human lives in the community area, a safe and pleasant urban environment with nature has developed to improve the city's space. The ultimate purpose of urban residents make to live on the city's creative environment, through the creative environment of public space as possible between the residents and the environment survives the interaction occurs can be called the space of communication. In this paper, survey about an independent organization of the public cultural center Facilities and utilization of the residents in Busan should investigate the connecting relationship between borough and identity. and through the comparisons between the public cultural center, analysis is to investigate the residents consciousness. These studies will be able to local residents about the volunteer doctors inspire a sense of responsibility and come up with a plan for improved quality of the public cultural center.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1201-1210
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• 2007

The urban streets as a featured and well performing public space for people should be organized in a way that can work as a whole system through network as well as that can provide amenities fur pedestrian. This is a study on Seattle's 'Blue Ring' project for an analysis focused on how its street weaving system organized and what are the design characteristics of the streets. The results are as followings. (1)Pedestrian oriented design, (2)Urban street as a part of open space that can accommodate human activities, (3)Integrated, not isolated with outer/ other open space, (4)Organically networked in a hierarchical manner that can promote pedestrian movement, (5)Utilization of regionally identical design elements. And Smart Growth concept lies in the core of 'Blue Ring' project.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.219-237
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• 2020

Rapid economic development and urban population growth have been increasing the necessity for underground space exploration and utilization due to the need of upgrading and expanding the existing infrastructures. TBM has been widely used to construct underground structures with high advance rate and minimal ground disturbance. Two important design parameters, which are available thrust capacity and cutterhead torque, should be estimated for any project in addition to proper selection of TBM type. However, the conventional thrust force and torque estimation model only depends on the empirical equation, which hinders the design process of the optimal thrust hydraulic system and the appropriate hydraulic components. In this study, four thrust and torque calculation models are derived and explained. For TBM design practice, the four estimation models are compared and discussed.

• Journal of the Korea Society of Computer and Information
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• v.26 no.9
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• pp.73-79
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• 2021

As the importance of online virtual space grows due to Corona Pandemic, interest in virtual space utilization technology is increasing, causing a boom in the growth of the untact technology and related content industry, and accelerating the transition to Metaverse era, a new virtual convergence platform based on virtual and reality. This study analyzed ZEPETO, a Metaverse platform and found that it provides a creative space through Built-it and ZEPETO Studio, and offers items and contents with active economic activity. This is the result of an analysis centered on ZEPETO, so it varies depending on the Metaverse platform. We look to find key items to activate a Metaverse platform and how to make best use of virtual assets crated in Metaverse in reality through Metaverse related technologies.

• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.113-124
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• 2021

Underground environmental infrastructure and energy production facilities, which are recognized as avoidable facilities such as landfills, are emerging as an important social issue due to urbanization and economic growth. In order to safely construct a large-scale plant facility in the underground space, it is necessary to increase the utilization of the limited space layout and minimize unnecessary columns. In this study, the plant modularization method(Pipe Rack Module) was reviewed to solve the problems of work constraints, assembly and demolition, process system interconnection, and maintenance that occur when plant facilities are underground. In addition, plant module analysis was performed by applying various load conditions (earthquake load, device load, earth pressure load, etc.) to improve spatial layout usability and secure structure stability. Based on the analysis results under various boundary condition, the implications regarding the minimum installation interval and module arrangement (draft) of basic modules required for the construction of an underground combined plant were derived.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.375-383
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• 2021

Due to COVID-19, people are building new lifestyles such as online shopping, online travel, and video conferencing by limiting going out and gatherings. Such rapid social change is causing new problems and deepening existing problems at the same time. In particular, as online consumption increases significantly, traffic congestion, air pollution, and the heavy workload of delivery drivers are deepening in the daily logistics industry, and face-to-face delivery is emerging as a new problem. With the advent of the 4th industrial revolution, unmanned delivery using drones, artificial intelligence, and autonomous driving is emerging as an alternative to the existing logistics industry. However, space for logistics facilities and securing additional logistics sites due to drone flight are emerging as new problems to be solved. Therefore, it is intended to link additional services such as logistics movement, storage, and delivery by utilizing the existing transportation business, the subway, as a space for a logistics facility for drones that can solve existing problems and new problems.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.40-46
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• 2022

Hall thrusters are one of the electric propulsion, where ions are accelerated to generate thrust and are widely utilized in space missions due to their high specific impulses. Recently, as the utilization of small and micro satellites with the mass of similar or less than 100 kg is highly increasing, the importance of research and development of the low-power electric propulsion is also raised. In this study, we developed two sub-200 W or less class, laboratory model Hall thrusters and measured the thrust and analyzed the discharge characteristics. Consequently, we obtained 2.5-9.0 mN of thrust, 600-1,150 s of specific impulse, and 15-28% of anode efficiency at 50-175 W of anode power.