• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.339-350
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• 2003

Engineering qualification model payload for a communications and broadcasting satellite(CBS) was developed by ETRI from May, 2000 to April, 2003. For. the purpose of functional test and verification of the payload, a real-time hardware-in-the-loop(HITL) CBS simulator(CBSSIM) was also developed. We assumed that the spacecraft platform for the CBSSIM is a geostationary communication satellite using momentum bias three-axis stabilization control technique based on Koreasat. The payload hardware is combined with CBSSIM via Power, Command and Telemetry System(PCTS) of Electrical Ground Support Equipment(EGSE). CBSSIM is connected with PCTS by TCP/IP and the payload is combined with PCTS by MIL-STD-1553B protocol and DC harness. This simulator runs under the PC-based simulation environment with Windows 2000 operating system. The satellite commands from the operators are transferred to the payload or bus subsystem models through the real-time process block in the simulator. Design requirements of the CBSSIM are to operate in real-time and generate telemetry. CBSSIM provides various graphic monitoring interfaces and control functions and supports both pre-launch and after-launch of a communication satellite system. In this paper, the HITL simulator system including CBSSIM, communications payload and PCTS as the medium of interface between CBSSIM and communications payload will be described in aspects of the system architecture, spacecraft models, and simulator operation environment.

• The KIPS Transactions:PartA
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• v.16A no.6
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• pp.463-472
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• 2009

Real-time operating systems must have satisfying various conditions such as effective scheduling policies, minimized interrupt delay, resolved priority inversion problems, and its applications to be completed within desired deadline. The real-time operating systems, therefore, should be designed and developed to be optimal for these requirements. MicroC/OS-II, a kind of Real-time operating systems, uses the basic priority inheritance with a mutex to solve priority inversion problems. For the implementation of mutex, the kernel in an operating system should provide supports for numerous tasks with same priority. However, MicroC/OS-II does not provide this support for the numerous tasks of same priority. To solve this problem, MicroC/OS-II cannot but using priority reservation, which leads to the waste of unnecessary resources. In this study, we have dealt with new design a protocol, so called TPSP(Temporary Priority Swap Protocol), by an effective solution for above-mentioned problem, eventually enabling embedded systems with constrained resources environments to run applications.

• Nuclear Engineering and Technology
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• v.25 no.2
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• pp.276-284
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• 1993

The ABB-CE System-80 reactor power cutback system(RPCS) is designed to enable continuous operation of the reactor without trip in the events of the loss of one of the two main feedwater pumps and loss of load, and thus improves plant availability in a cost effective manner. In this study expansion of RPCS has been investigated for continuous reactor operation without trip in the event of an inward control element assembly(CEA) deviation including a single rod drop. Under the expanded function of RPCS the control system will provide a rapid core power reduction on demand by releasing CEAs to drop into the core and reduce the turbine power, if necessary, to follow the reactor power variation. This design feature which is included as the new design features to be incorporated in the ABB-CE System-80+ meets the EPRI advanced light water reactor(ALWR) requirements. For this study core analysis models of System-80+ have been developed to simulate the nuclear steam supply system(NSSS) response as well as the RPCS initiation of rapid CEA insertion. The results of this study demonstrate that the reactor trip can be avoided in the event of inward CEA deviation including a single rod drop by the RPCS initiation and thus the plant availability and capacity factor would be increased.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.521-530
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• 2011

Since aircraft fuel tanks have many interfaces connected to the airframe as well as the fuel system, they have been considered as one of the system-dependent critical components. Crashworthy fuel tanks have been widely implemented to rotorcraft and rendered a great contribution for improving the survivability of crews and passengers. Since the embryonic stage of military rotorcraft history began, the US army has developed and practised a detailed military specification documenting the unique crashworthiness requirements for rotorcraft fuel tanks to prevent most, hopefully all, fatality due to post-crash fire. The mandatory crash impact test required by the relevant specification, MIL-DTL-27422D, has been recognized as a non-trivial mission and caused inevitable delay of a number of noticeable rotorcraft development programs such as that of V-22. The crash impact test itself takes a long-term preparation efforts together with costly fuel tank specimens. Thus a series of numerical simulations of the crash impact test with digital mock-ups is necessary even at the early design stage to minimize the possibility of trial-and-error with full-scale fuel tanks. In the present study the crash impact simulation of a few fuel tank configurations is conducted with the commercial package, Autodyn, and the resulting equivalent stresses and internal pressures are evaluated in detail to suggest a design improvement for the fuel tank configuration.

• Korean Journal of Construction Engineering and Management
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• v.16 no.1
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• pp.92-100
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• 2015

This study proposes measures to improve management performance of construction projects by re-designing the organizational structures of the Regional Construction Management Administrations of the Ministry of Land, Infrastructure and Transport. The re-designing measures are derived based on the three measures which were established by analyses on status of the Regional Construction Management Administrations, requirements from the current organizational structure, and domestic/overseas examples; the measures are: 1) organizational integration and scope expansion, 2) structural re-organization according to construction projects, and 3) building a knowledge management structure. In order to realize the re-designing measures, sixteen tasks are derived; a milestone is established according to importance, feasibility and lead-lag relationships of these tasks. If these tasks are to be carried out successfully, the management performance of the Regional Construction Management Administrations of the Ministry of Land, Infrastructure and Transport will be expected to improve. Ultimately, the Regional Construction Management Administrations can reduce cost and improve the quality of public service by outsourcing the non-core competence tasks and by concentrating on the construction management for the new infrastructure projects.

• Korean Journal of Construction Engineering and Management
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• v.11 no.6
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• pp.89-99
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• 2010

Military Barracks and Bachelor Officer's Quarters are public buildings representing architectural characteristics with repeating the same room modules. These buildings require easy dismantling and reusing for the next generation' military re-organization. For these reasons, since 2005, the modular construction has been applied to military buildings. The most important factors required for modular military buildings are standardization, lowcost construction and reusable construction method. However, conventional modular building system have not been matched with these requirements. This study suggests a new modular system for Bachelor Officer's Quarters using Six-sigma design tool. To reflect the voices of customers, market study and surveys were carried out. Through the QFD, the voices of customers were converted into quality characteristics of building system for BOQ. The various design concepts meeting customer's requirement were derived by the QFD and Pugh matrix methodology. The proposed modular building system shows 80% increased factory production rate and 62% decreased weight of steel frame as compared with the conventional modular building system.

• Spatial Information Research
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• v.23 no.4
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• pp.57-66
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• 2015

At these day, owing to functional limitations and cost issues, used image map in web service have a problem which can not make exactly meet the user needs. This study aims to create an individual map for user suitable purposes using HTML5 technology that implement the vector map creation and its functions with services. The results of this study, the invisible problems of the tilting and rotation functions in image-based map utilizing the existing web environment were solved in HTML5 vector map. And to access the map information, by implementing the function of expressing the background and name data to selectively derive, various results were expressed in the map. Also, as a result of a comparison of performance the time required was measured at 0.88sec which comes in the range of the first loading time between 0.78sec and 7.56sec in a commercial map service, which showed the possibility of its commercialization. compared to 180GB of image maps for the production of a national map index system, the volume to produce a vector map was 2.5GB, a decrease by over 90%, which solved the issue of costs for a storage space. As a result, this study of HTML5 vector map design and implementation presented a plan for providing information suitable for the requirements of the users who use spatial information through utilizing a variety of information and expanding functions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.29-45
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• 2017

Ad hoc sensor network is characterized by decentralized structure and ad hoc deployment. Sensor networks have all basic features of ad hoc network except different degrees such as lower mobility and more stringent energy requirements. Existing protocols provide different tradeoffs among some desirable characteristics such as fault tolerance, distributed computation, robustness, scalability and reliability. wireless protocols suggested so far are very limited, generally focusing on communication to a single base station or on aggregating sensor data. The main reason having such restrictions is due to maximum lifetime to maintain network activities. The network lifetime is an important design metric in ad hoc networks. Since every node does a router role, it is not possible for other nodes to communicate with each other if some nodes do not work due to energy lack. In this paper, we suggest an experimental ad-hoc on-demand distance vector routing protocol to optimize the communication of energy of the network nodes.The load distribution avoids the choice of exhausted nodes at the route selection phase, thus balances the use of energy among nodes and maximizing the network lifetime. In transmission control phase, there is a balance between the choice of a high transmission power that lead to increase in the range of signal transmission thus reducing the number of hops and lower power levels that reduces the interference on the expense of network connectivity.

• The Journal of Sustainable Design and Educational Environment Research
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• v.18 no.4
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• pp.58-65
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• 2019

Under the regulation of rational energy use in public institutions, it has been mandatory for educational facilities to meet the first grade or higher since 2014. Also the regulation has forced educational facilities as public institutions to use renewable energy since September 2008. Educational facilities are required to be qualified as zero-energy buildings from 2020 under the revision of the Green Building Act. In this study, we identified the current status of the building energy efficiency rating system and the renewable energy system installation for 316 educational facilities that were accredited as "building energy efficiency rating system" from February 2015 to March 2019. Also we analyzed the energy self-sufficiency rate based on energy requirements and renewable energy output. Of the 316 facilities, 12 had 1++ and 293 had 1++ for the "Building Energy Efficiency Rating System". Among the 12 facilities which had 1+++, 11 recorded ZEB level 5 or higher, and 28 out of the 293 facilities(11%) which got received 1++ had ZEB level 5. Thus, it is impossible to implement the ZEB certification system for educational facilities under the present conditions. Expanding the ratio of 1+++ and investing in renewable energy systems should be preceded.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.8
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• pp.913-920
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• 2011

We describe the evaluation of the fatigue life and strength of a lightweight railway bogie frame made of glass fiber/epoxy 4-harness satin-woven composites. To obtain the S-N curve for the evaluation of the fatigue characteristics of the composite bogie frame, we performed a tension-compression fatigue test for composite specimens with different stacking sequences of the warp direction, fill direction, and $0^{\circ}/90^^{\circ}$ direction. We used a stress ratio (R) of -1, a frequency of 5 Hz, and an endurance limit of $10^7$. The fatigue strength of the composite bogie frame was evaluated by a Goodman diagram according to JIS E 4207. The results show that the fatigue life and strength of the lightweight composite bogie satisfy the requirements of JIS E 4207. Given its weight, its performance was better than that of a conventional metal bogie frame based on an SM490A steel material.