• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.128-135
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• 2015

Currently we have an electro-optical space object monitoring system (OWL-Net) developed by the Korea Astronomy and Space Science Institute as the only ground-based on orbit space object tracking capability in Korea. This system can produce the ephemeris of domestic satellites and survey the geosynchronous orbit region. As the number of observation objects increases and the operation condition get worse, a low budget dedicated monitoring telescope capable of full time geosynchronous orbit region survey can support an effect operation of the OWL-Net. In this study, we analyze the requirements of a low-budget dedicated optical monitoring system for geosynchronous orbit region without the degradation of observation quality to increase the risk of corrupted ephemeris.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.68-76
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• 2022

The purpose of this paper was to design the cable networks for mesh reflector antennas, considering the flexibility of structures. An effective form-find methodology is proposed. The whole parts of the cable networks are described by the absolute nodal coordinate formulation. Additionally, nonlinear deformation of the cable can be obtained. The form-finding analysis of the reflector with standard configuration is performed, to validate the proposed methodology. The truss ring structure is numerically modeled using the frame elements. To consider the flexibility of the truss ring as well as the cable net structure, an iteration analysis between the truss ring and the cable net under tensional forces is also performed in the form-finding process. The finial configuration of the reflector with tensioned cable networks is demonstrated.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.368-373
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• 2005

This paper presents a new framework for the traffic flow control based on integrated model descriptions as the Hybrid Dynamical System (HDS).

• Journal of the Korean housing association
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• v.10 no.4
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• pp.71-81
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• 1999

The purpose of this study is to propose a way of making the master's space of the apartment suitable for new housing need. This study is to research the typology of master's space which is one of the major component of apartment plan. And also transition of the typology and size of master's space were analyzed. The 895 examples of unit floor plan were selected and classified according to the net area. The object of this study is the apartment plan which were constructed in Seoul, Il-san and Bun-dang and whose area is above 100 ㎡. Through this analysis and research, this study is to provide the basic data for actual design process and to suggest future trends of apartment houses.

• Nuclear Engineering and Technology
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• v.43 no.6
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• pp.523-530
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• 2011

In a previous study, the stochastic space-dependent kinetics model (SSKM) based on the forward stochastic model in stochastic kinetics theory and the Ito stochastic differential equations was proposed for treating monoenergetic space-time nuclear reactor kinetics in one dimension. The SSKM was tested against analog Monte Carlo calculations, however, for exemplary cases of homogeneous slab reactors with only one delayed-neutron precursor group. In this paper, the SSKM is improved and evaluated with more realistic and complicated cases regarding several delayed-neutron precursor groups and heterogeneous slab reactors in which the extraneous source or reactivity can be introduced locally. Furthermore, the source level and the initial conditions will also be adjusted to investigate the trends in the variances of the neutron population and fission product levels across the reactor. The results indicate that the improved SSKM is in good agreement with the Monte Carlo method and show how the variances in population dynamics can be controlled.

• Journal of Astronomy and Space Sciences
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• v.34 no.4
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• pp.303-314
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• 2017

With increased human activity in space, the risk of re-entry and collision between space objects is constantly increasing. Hence, the need for space situational awareness (SSA) programs has been acknowledged by many experienced space agencies. Optical and radar sensors, which enable the surveillance and tracking of space objects, are the most important technical components of SSA systems. In particular, combinations of radar systems and optical sensor networks play an outstanding role in SSA programs. At present, Korea operates the optical wide field patrol network (OWL-Net), the only optical system for tracking space objects. However, due to their dependence on weather conditions and observation time, it is not reasonable to use optical systems alone for SSA initiatives, as they have limited operational availability. Therefore, the strategies for developing radar systems should be considered for an efficient SSA system using currently available technology. The purpose of this paper is to analyze the performance of a radar system in detecting and tracking space objects. With the radar system investigated, the minimum sensitivity is defined as detection of a $1-m^2$ radar cross section (RCS) at an altitude of 2,000 km, with operating frequencies in the L, S, C, X or Ku-band. The results of power budget analysis showed that the maximum detection range of 2,000 km, which includes the low earth orbit (LEO) environment, can be achieved with a transmission power of 900 kW, transmit and receive antenna gains of 40 dB and 43 dB, respectively, a pulse width of 2 ms, and a signal processing gain of 13.3 dB, at a frequency of 1.3 GHz. We defined the key parameters of the radar following a performance analysis of the system. This research can thus provide guidelines for the conceptual design of radar systems for national SSA initiatives.

• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.441-452
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• 2004

Nowcast and forecast based on realtime data are quite essential for space weather monitoring. We have developed the web pages (http://sun.kao.re.kr) of the KAO Space Weather Monitoring system by using ION (IDL on the Net). They display latest solar and geomagnetic data, and present their expected effects on satellite, communications and ground power system. In addition, daily NOAA/SEC prediction reports on the probability of solar X-ray flares, proton events and geomagnetic storms are provided. To predict the arrival times of interplanetary shocks and CMEs, two different types of prediction models are also implemented. A work is in progress to develop web-based database of several solar and geomagnetic activities. These data are automatically downloaded to our data server in every minute, or every day using IDL and FTP programs. In this paper, we will introduce more details on the development of the KAO Space Weather Monitoring system.

• Wind and Structures
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• v.10 no.6
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• pp.495-510
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• 2007

Wind pressure data have been collected on the tiled roof of a full-scale test house at Silsoe in the UK. The tiled roof was of conventional UK construction with a batten-space and bitumen-felt underlay beneath the interlocking concrete tiles. Pressures were monitored on the outer surface of selected tiles, at several locations within the batten-space, and beneath the underlay. Data were collected both with and without ventilator tiles installed on the roof. Little information appears to exist on the share of wind load between tiles and underlays which creates uncertainty in the design of both components. The present study has found that for the critical design case of maximum uplifts it would be appropriate to assign 85% of the net roof load to the tiles and 15% to the underlay when an internal pressure coefficient of -0.3 is used, and to assign 60% to the tiles and 50% to the underlay when an internal pressure coefficient of +0.2 is assumed (an element of design conservatism is inherent in the apparent 110% net loading indicated by the latter pair of percentage values). These findings indicate that compared with loads implied by BS 6399-2, UK design loads for underlay are currently conservative by 25% whilst tile loads are unconservative by around 20% in ridge and general regions and by around 45% in edge regions on average over roof slopes of $15^{\circ}-60^{\circ}$.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.195-199
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• 2006

In the field of video design, motion graphics tends to be realized to deliver a certain message properly incorporating basic motion graphics components such as space, form of expression, and time, and has continued to be used as a powerful communication tool. Many cases proved that title sequences were produced as a result of combination of a variety of quick images and effects with appropriately chosen sounds to meet the demands of audience. This study indicated that motion graphics began to be widely used as a more powerful video communication tool for title sequences and also applied for M-NET, DMB, CABLE TV, IPTV, and others.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.900-906
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• 2010

We analyse benefits and costs of investment on the assurance of aircraft design and development of related infrastructure. Although the discounted cash flow from the sales of aircrafts is found to be smaller than the amount of required investment, the net present value considering the effects of export increase, import substitution, and the accident cost reduction is very high. This justifies governmental investment, for the effects are not easily appropriated by private investors.