• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.324-331
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• 2018

The thermal environment on lunar surface is more severe than that of earth's surface or low earth orbit because of the long daytime and nighttime due to 28 days of rotation cycle of moon. Thus, analyzing heat flux on lunar lander at potential landing sites is important to determine the landing site in its initial design phase. In this study, thermal model of lunar regolith that can simulate lunar surface temperature was constructed for analyzing thermal characteristics according to the potential landing sites of lunar lander. The heat flux analyses were performed various latitudes of equator, mid-latitude, polar regions, lunar mare and highland. In addition, we also investigated the heat flux of lunar lander when it is landed on adjacent area to hill.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1089-1096
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• 2015

A marine helicopter should remain sufficiently upright to permit safe evacuation of all personnel with a flotation system. And the rule requires that after ditching in water, the adequate flotation time will allow the occupants to leave the rotorcraft. To this end, stability test of the emergency flotation system for Korean marine helicopter was performed by using "Froude scaling method" in water tank. Test configuration and conditions were determined in consideration of the helicopter loading condition and related specifications. Test results meet the stability requirements at sea state code 4 and sea state code 2 with puncture conditions.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.209-218
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• 2005

In this paper, we present an Active Optical Network(AON) . The AON uses the Dense Wavelength Division Multiplexing(DWDM) from optical communication access network of ring type, and will be able to provide the smoothly service in the Bandwidth on Demand by using DWDM. It supports the connection of the multiple wavelength and the Sub-Carrier from the optical gigabit ethernet switch. The Wavelength Add Drop Multiplexer(WADM) extracts a specific wavelength, and composes a node of the ring network. The specific wavelength becomes demultiplexing in the Sub-Carrier and it is distributed in the user The active connection of optical gigabit ethernet switch where the distribution of access network is started and access terminal connection equipment is possible. By the BoD from the AON it compares the buffer size which changes, and it analyzes. Also the Time delay of bit compares with the throughput of server The limit of amount of time is decided. Consequently it will be able to realize the dynamic use protocol and an efficient algorithm of the network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1190-1197
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• 2013

AESA(Active Electronically Scanned Array radar) radar is able to instantaneously and adaptively position and control the beam, and such adaptive beam pointing of AESA radar enables to remarkably improve the multi-mission capability. For this reason, radar resource management(RRM) becomes new challenging issue. RRM is a technique efficiently allocating finite resources, such as energy and time to each task in an optimal and intelligent way. This paper deals with a design of radar resource management algorithms and simulator implemented main algorithms for development of airborne AESA radar. In addition, evaluation results show that developed radar system satisfies a main requirement about simultaneous multiple target tracking and detection by adopting proposed algorithms.

• Archives of design research
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• v.17 no.2
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• pp.221-230
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• 2004

Existing usability testing method, particularly lab-based usability testing, has been widely implemented for development of user interface. However, the method has critical disadvantages such as high cost, time and effort, unnatural testing environment, and lack of user's direct participation in information architecture. With these backgrounds, this paper aims to develop the web-based participatory tool with particular focus on card sorting. Our tool was developed for allowing user to participate in card sorting with his own computer through web. All the data generated while user is participating in the test are automatically sent to the server, which makes it very easy to collect card sorting data. Users can drag cards of interface elements directly and build the interface structure in their own from their computer-screen so that they can represent their mental models on interface structure of testing website. These functions of our tool can help designers to implement card sorting without tedious and time consuming procedures and improve the method of usability testing by reinforcing user's active participation in building an information architecture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.207-214
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• 2008

Under future internet environment, wireless sensor networks will be used in a wide range of applications. A major problem for designing sensor protocol is developing the most energy efficient technique to monitor an area of interest for a long time since sensors have some constraints such as small and a limited energy level. In addition, data latency is often a critical issue since sensory data is transmitted via multi hop fashion and need to be delivered timely for taking an appropriate action. Our motivation for designing a data forwarding protocol is to minimize energy consumption while keeping data latency bound in wireless sensor networks. In this paper, we propose a data forwarding protocol that consists of wakeup scheduling and MAC protocols, the latter of which is designed to achieve load balancing. Simulation results show that the proposed framework provides more energy-efficient delivery than other protocol.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.32-38
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• 2015

Next generation military satellite communication systems have been developed for expanding capacity and survivability. As for expanding capacity, the communication systems require efficient techonology to use limited resource. So, next generation communication systems are expected to use MF-TDMA technology. MF-TDMA is the technology which has the advantages of FDMA and TDMA. By using MF-TDMA, communication systems can use limited resource efficiently, and the performance of resource allocation depends on the allocation scheme. In this paper, we propose efficient allocation scheme for next generation military satellite communication systems. Also, we compare and analze performances such as Total Resource Efficient, Reject Ratio, Computational Time, PSD distribution with existing allocation schemes.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.5
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• pp.380-388
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• 2017

The services of the IoT environment should constantly collect situation information, and perform appropriate actions according to the situation. Therefore, there is a need for a method that can express collected situation information. In this paper, we propose a situation information model based on ontology for IoT environment. Since the proposed model is ontology based, it supports semantic interoperability. We also build an upper-level ontology to model common situation information of various IoT domains. It is easy to understand and use because it expresses situation information consistently by expressing person, environment, and thing constituting IoT environment as class and defining properties indicating the situation. In addition, since the situation information need to reflect dynamic situation, it has a feature to model the creation time and the life time of the situation information so as to judge the validity of the information. The proposed ontology model is described using OWL, and the service can be described based on the constructed ontology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1279-1283
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• 2008

Satellite Digital Multimedia Broadcasting(SDMB) needs Gap Fillers(GFs) to cover the non-service areas. However, SDMB mobile phones which are not located in GFs service area receive signals directly from the satellite because it is impossible to cover all SDMB service with GFs. Therefore, there is a border between the GFs service coverage and the satellite service coverage and it causes a time delay in signals which are from the GFs or the satellite. The time delay is the reason why SDMB service deteriorates. In this paper, I show how to reduce the deterioration of SDMB service in the border area between the GFs and the satellite adding the time delay to the satellite signal and the GFs signal. I think that this method is helpful in reducing the deterioration, especially in the early stages of SDMB service, which the GFs are not spread all over the nation yet.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.503-506
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• 2006

In this paper, we suggest the Agent System for management and service of science and technology information that performs the collection, analyzing, processing and managing the information. Generally, any system can process the collection and service the information as usual method, but that mean can't be clear because of the data process method on different systems of hardware and software. So, it's very important point that the design and development of S&T information flow framework that can accept the various data, and we expect that the agent system adapted in framework guarantee the reduction of man power and process time and the enlarged system. Agent System consists of five multi agents, Resource Format Register Agent, Data Collector Agent, Data Analyzer Agent, Data Processor Agent and MetaDB Creator Agent. We describe the main roles and elements of agent systems.