• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.12-19
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• 2006

In this paper, we propose the bandwidth borrowing scheme which improves the performance of the cal admission control of the integrated GEO satellite networks. In general, target transmission rates of communications and streaming services are fixed, but data services do not have the target transmission rates. Therefore, we can control the transmission rates for data services flexibly according to the system loading situation. When the available bandwidth of the system is insufficient, the bandwidth borrowing scheme gives the bandwidth to request real time services by the transmission rates control of data services through packet scheduler. We make the queueing model for our system model and demonstrate the results through simulations. The simulation results show that there is a 8.7-35.2 dB gain at the total blocking probability according to the use of bandwidth borrowing scheme.

• Journal of the Korean earth science society
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• v.41 no.5
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• pp.437-446
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• 2020

The rapid demand for electric vehicles and energy storage systems has increased interest in energy storage devices worldwide. New technological alternatives are needed to reliably supply energy storage mineral resources such as lithium and vanadium, which are key materials for energy storage devices. Already, research and development activities are taking place in various countries on technologies that can directly secure lithium and vanadium. Accordingly, it is very important to analyze each country's technological trends through patent and paper analysis to establish effective research and development strategies and to set future technological development directions. This study analyzed trends in the development of new technologies and the current status of research and development at home and abroad through patent data from Korea, the United States, Europe, and Japan that were disclosed or registered from 1970 to October 2019, and the data searched for papers from January 2000 to October 2019. According to the analysis, the current growth stage of the technology related to energy storage minerals is in the beginning stage. Therefore, it is believed that a strategy to rapidly upgrade technology by combining the development of new technologies and demonstration of developed technologies is needed in order to lead the technology market and strengthen the competitiveness of technologies.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.87-95
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• 2014

Recently, there are increasing technical needs for foundation retrofit project such as vertical extension of apartment building. This paper focuses on the load distribution characteristics of existing and reinforcing piles when reinforcing pile is installed to the existing foundation. Allowable bearing load was initially applied on the foundation slab supported with four existing piles and then, one reinforcing pile was installed at the center of foundation slab and additional load was applied. The experimental results showed the Load Distribution Ratio (LDR) between existing and reinforcing piles converged after the applied load exceeded allowable bearing capacity of all piles. Laboratory tests were also performed for the cases of 60 %, 80 %, 100 % unloading level of allowable bearing load. After unloading step, one reinforcing pile was installed at the center of foundation slab and additional load was applied. The results showed that reloading load level at which LDR between existing and reinforcing piles converged decreased as the amount of unloading load increased.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.67-72
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• 2020

Satellite communication is not used by many people like mobile communication, but it is a necessary technology for public service and communication services, such as providing the Internet in military, disaster, remote education and medical services, island areas, and infrastructure vulnerable areas. However, on ships and aircraft, mobile communications requiring base stations are either unavailable or restricted in their use. In this paper, we used a Raspberry Pi board as the terminal device to communicate network through satellite modem and PPP protocol, and implemented two-way data link using the text message of the modem to connect to the Thuraya geo-stationary orbit network. In addition, I/O devices were connected to the controller of the terminal equipment to design and implement an IoT device system for ships that can remotely access the system under control and control I/Os and transmit measured data through various sensors.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1063-1068
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• 2008

When construction of high pressure jet-grouting is to be performed, it has been reported that applied cement slurry which hasn't got dried out can cause severe environmental pollution, and can flow into near streams and fish farms. Several laboratory tests were performed in this study in order to verify safety of paste-like grouting material that was developed newly to be applied to void in the ground. According to experimental test results, it is proved to be so safe that application of the newly developed flowable grouting material can prevent the materials from spilling into surrounding areas and is not harmful to fishes.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.479-481
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• 2003

Large number of coral reefs in Thailand waters make the use of satellite imagery probably the only practical method for their monitoring. This paper reports the result of detecting small shallow-water coral reef by using maximum likelihood classification technique. Combination of blue/green and near-infrared band ratio are used as spectral signatures derived from a Landsat 7 imagery covering western portion of the Gulf of Thailand. Result assessment reveals accuracy significantly over 60 percent. The result is encouraging and would be a basis for further study to realize the full potential and limitation of this technique.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.57-61
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• 2019

Nowadays, portable digital cameras such as smart phone cameras are being popularly used for entertainment and visual information recording. Given a database of geo-tagged images, a visual location recognition system can determine the place depicted in a query photo. One of the most common visual location recognition approaches is the bag-of-words method where local image features are clustered into visual words. In this paper, we propose a new bag-of-words-based visual location recognition algorithm using time-series streetview database. The proposed algorithm selects only a small subset of image features which will be used in image retrieval process. By reducing the number of features to be used, the proposed algorithm can reduce the memory requirement of the image database and accelerate the retrieval process.

• Spatial Information Research
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• v.21 no.4
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• pp.15-24
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• 2013

Recently, as the spatial information and various multimedia are fused together, the demand for the high value-added spatial information contents and the necessity of technology for spatial information security are increasing. However, since the current security policy is being managed independently by each system, there is a problem with unreliable or costly to modify or revise the security policy. Such problems occur frequently in the process of coordination or integration of the spatial information management systems that are used in public institutions and private companies. Therefore, in this paper, the access control system that could provide an integrated security policy for many spatial platforms and systems with expandable grammar and semantics was designed and implemented based on GeoXACML proposed by OGC. As the GeoXACML-based access control system designed and implemented in this paper follows the international standard specifications, it provides high portability and interoperability. Finally, in this paper, the efficiency of the system was proved by applying it to a virtual scenario on the military area requiring the access control.

• Journal of the Korea Society of Computer and Information
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• v.16 no.11
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• pp.35-44
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• 2011

Advances in science and technology have made a lot of changes in our life. Especially, sensors have used in various ways to monitor in real time and analyze the world effectively. Traditional sensor networks, however, have used their own protocols and architecture so it had to be paid a lot of additional cost. In the past 8 years, OGC and ISO have been formulating standards and protocols for the geospatial Sensor Web. Although the OGC SWE initiatives have deployed some components, attempts have been made to access sensor data. All spatial operations had to calculate on the client side because traditional SOS architecture did not consider spatial operation for GeoSensor. As a result, clients have to implement and run spatial operations, and it caused a lot of overload on them and decreased approachableness. In this paper we propose S-SOS for in-situ and moving GeoSensor that extends 52 North SOS and provides spatialFilter and spatialFinder operations. The proposed S-SOS provides an architecture that does not need to edit already deployed SOSs and can add spatial operations as occasion. Additionally we explain how to express the spatial queries and to be used effectively for various location based services.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.151-151
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• 2021

The alarming climate change impacts are demanding the use of renewable energy sources like never before. Hydropower is one of the most cost-effective and environmental friendly energy technology recognized in the world. Big hydropower projects come up with the requirements of huge investment costs along with environmental impacts, whereas small hydropower(SHP) are considered a best solution for the economical source of energy. SHP, basically Run-of-River (RoR) type plants can be sustainable renewable energy sources and given the nature of perennial rivers flowing from steep gradient and rugged topography, feasibility of such plants is equally high in Nepal. The objective of this study is to determine the primary potential sites for the development of RoR type SHP sites using Geo-spatial Information System(GSIS). The use of GSIS enables precise survey of large area within a short period of time. This study has focused on the determination of locations by establishing defined criterions and methodologies and hence have located multiple locations rather than selecting one best location. The approach is applicable for the rapid initial screening of potential locations and results can facilitate detail feasibility study for the technical and economic analysis of SHP in the basin.