• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.4
• /
• pp.535-550
• /
• 2016

Securing the safety and the reliability of liquid-propellant rocket engines (LREs) for space vehicles is indispensable as engines consist of many complex components and operate under extremely high energy-dense conditions. Thus, health monitoring has become a mandatory requirement, especially for the reusable LREs that are currently being developed. In this context, a dynamic simulation program based on MATLAB/Simulink was developed in the current research on the Space Shuttle Main Engine (SSME), a partly reusable engine. Then, a series of fault simulations using this program was conducted: at a steady state operating condition (104% Rated Propulsion Level), various simulated fault conditions were artificially injected into the simulation models for the five major valves, the pumps, and the turbines of the SSME. The consequent effects due to each fault were analyzed based on the time responses of the major parameters of the engine. It is believed that this research topic is an essential pre-step for the development of fault detection and diagnosis algorithms for reusable engines in the future.

• Journal of the Korean Institute of Educational Facilities
• /
• v.12 no.3
• /
• pp.22-32
• /
• 2005

This paper is to propose a design possibility that incorporates participatory process and also to emphasize the participatory process applied to the planning of outdoor playground space open to the neighboring community. Community design based on the participation method can be understood as an attitude about a force for change in the creation and management of environments for people who are the major users of them. Planning for outdoor space is an integral part of school education and a vital component of child development. For the design of outdoor space of Samyang Elementary School it first needs to examine the current and emerging needs of students, teachers and parents as community residents through the participatory design method. A series of workshops and interviews are taken to identify dreams and ideal spaces of each group. An assessment of existing school spaces and design possibility of reprogrammed outdoor spaces are proposed to match the major demands of participants. Selected outdoor places are chosen and designed to accommodate options for various play settings and to make the school pleasant places where members of the neighborhood can gather for relaxation in restful surroundings.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.2
• /
• pp.30.3-31
• /
• 2015

We present a kinematic analysis of 172 likely member galaxies of the Ursa Major Cluster. In order to understand the dynamical state of the cluster, we investigate the correlation of the cluster morphology with rotation, the velocity dispersion profile, and the rotation amplitude parallel to the global rotation direction. Both the minor axis and the rotation are very well-aligned with the global rotation axis in the outer region at half radius (> 0.5 $R_{max}$), but not in the inner region. The cluster exhibits low velocity dispersion and rotation amplitude profiles in the inner region, but higher in the outer. Both profiles exhibit outwardly increasing trends, suggesting an inside-out transfer of angular momentum of dark matter via violent relaxation, as revealed by a recent off-axis major-merging simulation. From Dressler-Schectman plots in the plane of galactic positions, and velocity versus position angle of galaxy, we are able to divide the Ursa Major Cluster into two substructures: Ursa Major South (UMS) and Ursa Major North (UMN). We derive a mass of $3.2{\times}10^{14}M_{\odot}$ for the cluster through the two-body analysis by the timing argument with the distance information (37 for UMN and 36 for UMS) and the spin parameter of ${\lambda}=0.049$. The two substructures appear to have passed each other 4.4 Gyr ago and are moving away to the maximum separation.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.2
• /
• pp.59.5-60
• /
• 2017

We present the relationship between vector magnetic field parameters and solar major flare occurrence rate. Based on this, we are developing a forecast model of major flare (M and X-class) occurrence rate within a day using hourly vector magnetic field data of Space-weather HMI Active Region Patch (SHARP) from May 2010 to April 2017. In order to reduce the projection effect, we use SHARP data whose longitudes are within ${\pm}60$ degrees. We consider six SHARP magnetic parameters (the total unsigned current helicity, the total photospheric magnetic free energy density, the total unsigned vertical current, the absolute value of the net current helicity, the sum of the net current emanating from each polarity, and the total unsigned magnetic flux) with high F-scores as useful predictors of flaring activity from Bobra and Couvidat (2015). We have considered two cases. In case 1, we have divided the data into two sets separated in chronological order. 75% of the data before a given day are used for setting up a flare model and 25% of the data after that day are used for test. In case 2, the data are divided into two sets every year in order to reduce the solar cycle (SC) phase effect. All magnetic parameters are divided into 100 groups to estimate the corresponding flare occurrence rates. The flare identification is determined by using LMSAL flare locations, giving more numbers of flares than the NGDC flare list. Major results are as follows. First, major flare occurrence rates are well correlated with six magnetic parameters. Second, the occurrence rate ranges from 0.001 to 1 for M and X-class flares. Third, the logarithmic values of flaring rates are well approximated by two linear equations with different slopes: steeper one at lower values and lower one at higher values. Fourth, the sum of the net current emanating from each polarity gives the minimum RMS error between observed flare rates and predicted ones. Fifth, the RMS error for case 2, which is taken to reduce SC phase effect, are smaller than those for case 1.

• Korean Institute of Interior Design Journal
• /
• v.15 no.4 s.57
• /
• pp.156-164
• /
• 2006

One of frequent phenomena in the contemporary cultural field is the alternative or accompanying interweaving phenomena which happens in the relative connection of A, B, and C. The power of interweaving mixture is one of energies which unify the contemporary cultural phenomena, and it appears as a major phenomena in the recent popular digital architecture. In this study, the mixture, shape, and contents in the contemporary space design is analyzed as a point of view of Post-Structuralism. Namely, the digital part and non-digital part of alternative and circulating existence in the space are classified and the interweaving phenomena in the contemporary space design are proved. It is studied for digital part and physical space to conjunct the hole space and smooth space of Deleuze as part of interweaving phenomena. It is clear that the compatible concept of the hole space and smooth space is crossed complexly or is coexisting in circulating and extending, and is showed as interweaving phenomena in one space.

• Journal of Korean Library and Information Science Society
• /
• v.51 no.2
• /
• pp.245-272
• /
• 2020

The purpose of this study is to analyze the current status of space use in university library and draw up considerations for enhancing space utilization based on the analysis results. For this purpose, the utilization rate of each space was analyzed by categorizing the user's space of the university library, and secondly, the preferences of the major user groups were analyzed according to the characteristics of the users' space. For empirical analysis, we collected and refined users' space usage data (98,282 people's data 433,769 cases) accumulated for one year for the central library of "J" National University. Then we analyzed the usage pattern according to space and period(monthly, hourly). In addition, preferences for each major group of users (undergraduates, graduate students and graduates) in the library were analyzed through the library visitors' data (2,426,553 cases) over the same period. The results of this study can be used as preliminary research for the composition and arrangement of users' space in future university libraries.

• The Korean Journal of Air & Space Law and Policy
• /
• v.19 no.1
• /
• pp.57-77
• /
• 2004

According to the dispostions of 1967 Space Treaty, the contracting states should assume legal obligation to assure an authorization and continuing supervision with regard to the national space activities. Any space activities have to abide by the rules of international law as well as specified obligations set by the Treaty. Among several treaty obligations, International responsibility to be bome by the state, and the liability principles are deemed as major outstanding obligations which the state should takeinto account. While nation's first launch site is to be operational in a few years, korean government should assure that its national space activities, such as launching of space object, operation of satellites, etc. should be under governmental authorization and supervision. A legislative effort would be most desirable undertaking for this regard. Especially a specific legislation needs tobe studied forwith such authorization regime so that international responsibilty and the liability as to thelaunching of space object should be under the regulatory scheme. This study focuses upon the necessity of such legislation and proposes some major items and framework for the legislation

• Journal of Astronomy and Space Sciences
• /
• v.37 no.1
• /
• pp.1-9
• /
• 2020

Frozen orbit is an attractive option for orbital design owing to its characteristics (its argument of pericenter and eccentricity are kept constant on an average). Solar sails are attractive solutions for massive and expensive missions. However, the solar radiation pressure effect represents an additional force on the solar sail that may greatly affect its orbital behavior in the long run. Thus, this force must be included as a perturbation force in the dynamical model for more accuracy. This study shows the calculations of initial conditions for a lunar solar sail frozen orbit. The disturbing function of the problem was developed to include the lunar gravitational field that is characterized by uneven mass distribution, third body perturbation, and the effect of solar radiation. An averaging technique was used to reduce the dynamical problem to a long period system. Lagrange planetary equations were utilized to formulate the rate of change of the argument of pericenter and eccentricity. Using the reduced system, frozen orbits for the Moon sail orbiter were constructed. The resulting frozen orbits are shown by two 3Dsurface (semi-major, eccentricity, inclination) figures. To simplify the analysis, we showed inclination-eccentricity contours for different values of semi-major axis, argument of pericenter, and values of sail lightness number.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.606-608
• /
• 2003

This paper investigates the accuracy of three-dimensional positioning for EROS A stereo pairs when different numbers of ground control points are employed. The major works of the proposed schemes include: (1) initialization of orientation parameters (2) preliminary orbit fitting, (3) orbit refinement using the least squares filtering technique, and (4) space intersection. The experiment includes validation of positioning accuracy for an EROS A in-track stereo pair when different number of check points are employed.

• Transactions of the Korean hydrogen and new energy society
• /
• v.32 no.6
• /
• pp.464-469
• /
• 2021

A reforming catalyst for hydrogen production from ammonia is being studied. Non-novel metal based Ni catalysts for use in ammonia reforming processes are being developed. In this study, the ammonia reforming characteristics according to Ni content of the alumina pellet supported catalyst in the mid-temperature region were investigated under different space velocity. 20 Ni and 3,000 h^-1 showed the best catalytic activity with ammonia conversion of 63% among all conditions.