• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.877-888
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• 2022

Recently, as the CAPSTONE, a precursor mission for Lunar Gateway, was launched on a small launch vehicle for the purpose of demonstrating communications and navigation technology in the NRHO, large attention was brought to this event that enabled high-impact deep space mission using dedicated small launch vehicle and small spacecraft. In this study, we introduced the concept of a dual launch operation and examined the capability of the new concept in the exploration of the Moon, Mars and asteroid. It turned out a single launch is sufficient for the lunar low orbit mission up to around 247 kg, and the dual launch option can transport 215 kg and 183 kg to nearby destinations as such as Mars and astroid Apophis respectively.

• Journal of the Korean Mathematical Society
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• v.41 no.6
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• pp.1035-1047
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• 2004

In this paper, we study the unit tangent sphere bundles T$_1$M(4c) of complex space forms M(4c) with constant holomorphic sectional curvature 4c. In particular, we determine T$_1$M(4c) whose Ricci tensors satisfy the Einstein-like conditions.

• Management Science and Financial Engineering
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• v.17 no.2
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• pp.23-37
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• 2011

In this paper, we address a layout design problem for determining an optimal 4-class-based dedicated linear storage layout in a class of unit load storage systems. Assuming that space requirement for a class is the sum of the maximum inventory levels of products assigned to the class, and that one-way travel time is a linear function of storage index, we formulate a 4-class-based dedicated linear storage problem PTL[4] and provide an exact splitting algorithm with $O(n{\lceil}logn{\rceil})$. Our algorithms could be applied to more than a 4-class-based dedicated storage layout problem with slight modification in order to reduce computational execution time.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.675-682
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• 2021

The study analyzes the demand for residential space in the Untact Era. Residential space comprises six categories: the most necessary dedicated space (DS), most preferred south-facing space (SFS), largest space (LS), most necessary shared space (SS), most necessary infra-space (IS), and others. Results indicated the following: 1) All respondents had the highest preference for relaxing spaces except DS. 2) Differences were found between DS, SFS, and LS by age and SS; IS by residential area; and DS, SS, and IS by household size. 3) People aged 60+ preferred a living room while people aged 40-59 preferred a larger kitchen. Seoul citizens preferred gardens or parks in the complex or neighboring forests whereas local citizens preferred shared offices and medical centers. Households of three or more persons preferred a park/forest and two-person households preferred a honbap restaurant. The implications for housing policy are as follows. 1) Nature-friendly spaces are needed to alleviate a sense of isolation. 2) Changing demand for residential space should be reflected in housing policies. 3) The government's housing supply policy with the same residential space and structure must be changed to provide various residential spaces according to age, residential area, and household size.

• Journal of Power Electronics
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• v.13 no.5
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• pp.787-797
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• 2013

Despite the advantages offered by multilevel inverters, one of the main drawbacks that prevents their widespread use is their circuit complexity as the number of power switches employed is usually high. This paper presents a new multilevel inverter topology with a considerable reduction in the number of power switches used through the switch-sharing approach. The fact that the proposed inverter applies two bidirectional power switches for sharing among the three phases does not prevent it from producing seven levels in the line-to-line output voltage waveforms. A modified scheme of space vector modulation via the application of virtual voltage vectors is developed to generate the PWM signals of the power switches. The performance of the proposed inverter is investigated through MATLAB/SIMULINK simulations and is practically tested using a laboratory prototype with a DSP-based modulator. The results demonstrate the satisfactory performance of the inverter and verify the effectiveness of the modulation method.

• Journal of Astronomy and Space Sciences
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• v.2 no.1
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• pp.1-6
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• 1985

The U.S. Space Shuttle represents the beginning of a new era in transportation and is the critical element in the industrialization of the near-Earth-space. Most of its flights are dedicated to reducing costs launching commercial satellites. However, it provides a microgravity environment for processing unique and improved materials which is generating great interest in both civilian and military sectors. The space shuttle is also the necessary step in establishing a permanent space station which could host materials analysis laboratories and commercial processing facilities. This paper reviews the different elements of the space shuttle transportation system, a typical mission scenario, and discusses current activities in materials processing in space.

• 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.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.5-9
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• 2017

This paper provides an overview of the AKARI mission, which was the first Japanese satellite dedicated to infrared astronomy. The AKARI satellite was launched in 2006, and performed both an all-sky survey and pointed observations during its 550 days in the He-cooled mission phases (Phases 1 and 2). After the He ran out, we continued near-infrared observations with mechanical cryocoolers (Phase 3). Due to a failure of its power supply, AKARI was turned off in 2011. The AKARI data are unique in terms of the observed wavelengths as well as the sky coverage, and provide a unique legacy resource for many astronomical studies. Since April 2013, a dedicated new team has been working to refine the AKARI data processing. The goal of this activity is to provide processed datasets for most of the AKARI observations in a Science Ready form, so that more users can utilize the AKARI data in their astronomical research. The data to be released will include revised All-Sky Point Source Catalogues, All-Sky Image Maps, as well as high-sensitivity images and spectra obtained by pointed observations. We expect that the data will be made public by in the Spring of 2016.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.505-516
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• 2007

In this paper, we provide some fundamental properties and basic theoretical results of K-class-based dedicated storage policy in a unit load system assuming the constant-space assumption that the number of storage locations for a class is not the maximum aggregate inventory position for a class but the sum of space requirement for products assigned to the class. The main theorem is that there exists a (K+1) -class-based storage layout whose expexted single command (SC) travel time is not greater than that of a K-class-based storage layout, i.e, $E(SC^*_{K+1}){\leq}E(SC^*_K)\;for\;K=1,{\cdots}$, (n-1).

• Journal of IKEEE
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• v.14 no.2
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• pp.76-81
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• 2010

The need for dedicated hardware continue to decrease as the mobile CPU's performance increases. But, there is a limit to a mobile CPU's performance. GP-GPU(General-Purpose computing on Graphics Processing Units) can improve performance without adding other dedicated hardware. This paper presents the implementation of Inverse Quantization, Inverse DCT and Color Space Conversion module in H.264/AVC decoder using GP-GPU for a mobile environments. The proposed architecture improves approximately 40% of performance when it use all the features.