• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.38-41
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• 2009

For the technology development of LOx/kerosene liquid rocket engine, turbopump-gas generator closed-loop coupled tests using 30tonf main engine components such as turbopump and gas generator except combustion chamber are performed. In the engine system operation environment, simulating combustion chamber by flow control units, the chill-down procedure, startup characteristics, nominal operability and smooth shutdown of turbopump+gas generator closed-loop coupled Test Plant are successfully confirmed. The serviceability of the turbopump and gas generator are evaluated. The feed-back control system for the turbopump rotational speed and gas generator mixture ratio are also verified. The results of closed-loop coupled test will be used as the technology development for the liquid rocket engine.

• Journal of Digital Convergence
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• v.16 no.6
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• pp.117-126
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• 2018

This study investigated the antecedents of VR(virtual reality) headsets acceptance and the causal relationships among self-efficacy, content diversity, the perceived usefulness, the perceived easy of use, the perceived playfulness and the adoption intention. We collected 238 survey responses and formed structural equation modeling with AMOS 23.0. The results of the analysis can be summarized as follows. The diversity of contents and self-efficacy had significant effects on perceived usefulness, perceived ease of use and perceived enjoyment, thus increasing the intention of acceptance. Perceived usefulness, perceived ease of use and perceived enjoyment had significant effects on the intention of acceptance. Perceived ease of use indirectly had an effect through increasing perceived enjoyment. The price did not affect the adoption intention and marketing communication increased the intention of acceptance. The results are expected to provide useful information to the companies related to VR.

• Journal of Digital Contents Society
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• v.15 no.4
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• pp.533-545
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• 2014

According to the evolving of IT technologies, the amount of data we are facing increasing exponentially. Thus, the technique for managing and analyzing these vast data that has emerged is a distributed processing system of big data. A quality evaluation for the existing distributed processing systems has been proceeded by the structured data environment. Thus, if we apply this to the evaluation of distributed processing systems of big data which has to focus on the analysis of the unstructured data, a precise quality assessment cannot be made. Therefore, a study of the quality evaluation model for the distributed processing systems is needed, which considers the environment of the analysis of big data. In this paper, we propose a new quality evaluation model by deriving the quality evaluation elements based on the ISO/IEC9126 which is the international standard on software quality, and defining metrics for validating the elements.

• Journal of The Korean Association of Information Education
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• v.10 no.1
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• pp.25-35
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• 2006

Computer education currently executed at elementary schools showed problems of system of education curriculum, repetition, and lack of consistent system as a result of analyzing index for information and communication technology, education curriculum, and related literatures, and most of the education contents have difficulty to nurture logic thinking and problem-solving ability since they are composed mainly of software function learning. Concerning this issue, this study suggests an innovated computer education curriculum with reinforced information ethics field with computer principle, algorithm, and programming, in other words, a corrected and supplemented version of former content system based on computer science guidance cases of ACM education curriculum model of USA, computer education curriculum of state Tennessee, and information technology education curriculum of Great Britain judging that introduction of computer science factors are desperate to improve computer education curriculum in elementary schools.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.167-172
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• 2013

In recent years, mobile healthcare systems that transfer patient data wirelessly have been used in the medical field. However, the current messages supported to patients are difficult to satisfy the specific patients, and there is a lack of healthcare systems to help manage patients with diabetes or pregnant women on a regular basis. In this regard, this paper demonstrates that the semantic-web service to which data transfer method, application framework and networking of WPAN are applied can be implemented. In addition, it suggests common data types to integrate data from a variety of sources and provides a common framework in which information on the Web can be shared and reused in applications, businesses and communities, etc. As an example, the healthcare monitoring that can manage healthcare for pregnant women, which includes confirmation of pregnancy, periodic health management, fetal movement, prenatal care and health-related knowledge, is proposed.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.130-141
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• 2011

The intelligent excavating system(IES), the development in South Korea of which has been underway since 2006, aims for the full-scale automation of the excavation process that includes a series of tasks such as movement, excavation and loading. The core elements to ensure the quality and safety of the automated excavation equipment include 3D modeling of terrain that surrounds the excavating robot and the technology for detecting objects accurately(i.e., for detecting the location of nearby loading trucks and humans as well as of obstacles positioned on the movement paths). Therefore the purpose of this research is to ensure the quality and safety of automated excavation detecting the objects surrounding the excavating robot via a 3D laser scanning system. In this paper, an algorithm for estimating the location, height, width, and shape of objects in the 3D-realized terrain that surrounds the location of the excavator was proposed. The performance of the algorithm was verified via tests in an actual earthwork field.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.9-15
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• 2005

Most of location systems use RF signal. Because multipath is too severe at indoor environment, RF signal are usually used in outdoor positioning such as GPS. To overcome the difficulty at indoor positioning, m positioning is recently developed and is being vigorously studied. Some standardizations on UWB are in progress at IEEE 802.15 committee. In developing UWB positioning system, we should consider the synchronization of sensor network, positioning algorithm, sensor allocation, and so on. This paper presents a comparison of TDOA positioning algorithms that are widely used in location systems. Two algorithms are compared; one is derived by linearization, and the other is by analytic solution(CH algorithm). Simulation results show that the CH algorithm is superior to the linearized least square at indoor environment in that CH algorithm shows consistent positioning performance regardless of the visibility and geometry of basestations.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.25-32
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• 2005

Seismic load is distributed to modes of a structure through the modal participation factor(MPF). The modal participation factor is essential to analyze structural response under earthquake load. MPF of a real structure differs from that of analytical mathematical model due to the error induced from analytical assumptions and during the construction. In this study, an identification method is proposed to calculate the 1st MPF of real structure based on $H^{\infty}$ optimal model reduction. The MPF is obtained from the relationship between observability and controllability matrices realized from system identification and those of a prototype 2-degree state space model. The proposed method is verified thorough numerical examples.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.6
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• pp.61-72
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• 2014

We implemented ecological linkage assessment, through the connection components of the urban forests, rivers and parks, for the ecological connection of the urban parks which are standing out as the core of the urban green networks, so as to suggest basic data to compare, evaluate and improve urban green networks, as a basic study for the evaluation of the ecological connectabilities between the cities. For the ecological linkage assessment, we analyzed to see if the urban parks of Goyang, Ansan and Yongin, which are the subject cities, are actually ecologically connected with forests and rivers, using distance and roads, which are physical connection elements, in consideration of the mobility of the wild animals, and greening ratios and impervious pavement ratios, which are ecological connectabilities in consideration of the ecological values. The overall result of the ecological linkage assessment the physical connection elements and the ecological connection elements shows that the ecological green network ratio through direct connection states is 36.62% in Goyang, 42.55% in Ansan and 64.00% in Yongin, respectively, giving the ecological connectability ratio of less than half, with the average urban ecological green network ration of 47.72%. The comparison result of the ecological connectabilities between the object cities employing the connection elements indicates that when you set up green networks, you should consider together the physical connection elements, such as the roads, which will lower the ecological connectabilities - rather than do it simply based on areas and distances - while the ecological connection elements with the forests and the streams should be reinforced, so that the ecological connectabilities of the urban parks may be enhanced.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.3
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• pp.282-287
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• 1990

In this paper, it has been analysed that the stability and the effectivity of the solution using traditional transfer matrix method. And applying the false-position method to these, the convergence characteristics of the solution has been also analysed. As a result, the frontal transfer matrix method is superior to traditional transfer matrix method in the stability and the accuracy of the solution in high frequency region but in the economical efficiency and the effectivity of the calculation, traditional transfer matrix method is more desiable. Also, it is clear that $\omega-Det$ curve using the frontal transfer matrix method is discontinuous.