• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.251-258
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• 2018

This work illustrates the progress of a TAS activity at exploring the challenges and the benefits of the Virtual Shaker Testing (VST) approach. The definition and the validation of new computational methodologies with respect to the state of the art were encouraged throughout this activity. The shaker Finite Element (FE) model in lateral configuration was built for the purpose and it was merged with the SpaceCraft (S/C) FE model, together with the S/C-Shaker adapter. FE matrices were reduced through the Craig-Bampton method. The VST transient analysis was performed in MATLAB(R) numerical computing environment. The closed-loop vibration control is accounted for and the solution is obtained through the fourth-order Runge Kutta method. The use of pre-existing built-in functions was limited by authors with the aim of tracing the impact of all the problems' parameters in the solution. Assumptions and limitations of the proposed methodology are detailed throughout this paper. Some preliminary results pertaining to the current progress of the activity are thus illustrated before the conclusions.

• 한국가구학회지
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• 제22권1호
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• pp.1-12
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• 2011

Recently, the studio which is urban housing form is rapidly growing up by new residential space according to increasing 1~2 person households form because of Modern members who have changing patterns of life and diversification of social values. The resident of the studio who lives or uses the space for a work such as students, office worker and soho-jok has various characters by a society nature changes and a regional peculiarity. The studio form and function is getting change according to variety trend changes and their life styles. The role and use of residential space also have variety such as the resident who lives in the studio. This study is to find the space utilization for them and reasonable housing solution in that structure, furniture and Wall Storage System of existing studio which is based on the common life patterns. The study's purpose is to propose the furniture design of changeable Wall Storage System according to the analysis.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.27.1-27.1
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• 2011

This study is about the ionospheric variation on the Korean Peninsula using GPS TEC data from Daejeon IGS GPS site. It has accumulated the 11 years GPS data from 2000. In this work, the hourly and daily averaged TEC data are used. Data period covers a full solar cycle from 2000 to 2010 (11 years) which the total observed days are 98%. The mean TEC data shows the annual/semiannual variation, solar cycle and 27 days. GPS TEC has a good correlation with solar F10.7 index. We also compare with planetary Kp and AE indices. The maximum of the daily mean GPS TEC is around 50 TECU at 2000 and that value of 2009 is near 10 TECU. we confirms that the GPS TEC is a good indicator for ionospheric variation for the mid-latitudinal region to understand the ionospheric climatology over Korea Peninsula.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2065-2069
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• 2014

The DAC-7512E is a 12-bit digital to analog converter that is low power and a single package with internal buffers. The DAC-7512E takes up minimal PCB area for applications of space power electronics design. The spacecraft mass is a crucial point considering spacecraft launch into space. Therefore, we have performed a TID test for the DAC-7512E 12-bit serial input digital to analog converter to reduce the spacecraft mass by using a low-level Gamma-ray irradiator with $Co^{60}$ gamma-ray sources. The irradiation with $Co^{60}$ gamma-rays was carried out at doses from 0 krad to 100 krad to check the error status of the device in terms of current, voltage and bit error status during conversion. The DAC-7512E 12-bit serial digital to analog converter should work properly from 0 krad to 30 krad without any error.

• Management Science and Financial Engineering
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• 제11권2호
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• pp.61-84
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• 2005

This paper considers a special case of the two-dimensional bin-packing problem for identical items. The objective of this work is to maximize the space utilization. The main contribution of the paper is to suggest a new heuristic algorithm keeping in view the existing complexity of racking system for the footwear boxes in the compartments of different sizes for a warehouse. The results show that a significant improvement can be obtained. An economic choice of compartments is also estimated using the criteria for maximizing space utilization. A non-linear mathematical model was presented based on the constraints of racking dynamics.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.87-90
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• 2007

In cooperative communication systems, the source terminal transmits signal to the destination terminal with the aid of partner terminals. Therefore, the source terminal obtains extra spatial diversity gain. As a result, its performance is enhanced in term of higher achievable transmission rate, the larger coverage range, and the lower bit-error-rate (BER). Space-time codes (STCs) have been applied to cooperative communication systems in distributed fashion, in which the signal is spatially time exploited to obtain gains analogous to those provided by STCs. In this work, we consider the application of orthogonal Space-time Block Codes (OSTBCs) to the cooperative communication systems to further achieve higher diversity gain. The advances of the proposed approach are verified via computer simulations.

• Journal of Astronomy and Space Sciences
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• 제20권4호
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• pp.351-358
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• 2003

회전안정화 로켓 모터를 이용하는 우주 비행체의 자세 불안정 현상을 수치적 실험을 통하여 연구하였다. 이전 연구에서는 해석적 방법을 통하여 주어진 우주 비행체에 대한 정상해를 구하고 실제 발생했던 공진과 유사한 공진조건을 찾았으나 정상해 근방에서의 안정도 또는 파라미터 공간 전역에서의 안정도가 어떻게 변하는 지를 알 수가 없었다. 따라서, 본 연구에서는 이전 연구결과를 기초로 하여 주어진 파라미터 공간 전역에서 수치적 실험을 통하여 유동체의 파라미터 값에 따라 위성체의 자세 안정도가 어떻게 변화하는지를 관찰하고, 시스템 설계에 필요한 파라미터들의 안정/불안정 영역을 결정하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.186-188
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• 2005

Hand region detection in images is an important process in many computer vision applications. It is a process that usually starts at a pixel-level, and that involves a pre-process of color space transformation followed by a classification process. A color space transformation is assumed to increase separability between skin classes for hands and non-skin classes for other parts, to increase similarity among different skin tones, and to bring a robust performance under varying illumination conditions, without any sound reasonings. In this work, we examine if the color space transformation does bring those benefits to the problem of hand region detection on a dataset of images with different hand postures, backgrounds, people, and illuminations. Results indicate that best of the color space is the normalized RGB.

• 천문학회보
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• 제42권2호
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• pp.78.3-78.3
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• 2017

The positions of galaxies in comoving Cartesian space varies under different cosmological parameter choices, inducing a redshift-dependent scaling in the galaxy distribution. The shape of the two-point correlation of galaxies exhibits a significant redshift evolution when the galaxy sample is analyzed under a cosmology differing from the true, simulated one. In our previous works, we can made use of this geometrical distortion to constrain the values of cosmological parameters governing the expansion history of the universe. This current work is a continuation of our previous works as a strategy to constrain cosmological parameters using redshift-invariant physical quantities. We now aim to understand the redshift evolution of the full shape of the small scale, anisotropic galaxy clustering and give a firmer theoretical footing to our previous works.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.575-580
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• 2010

In this work, the electrophoretic motion of dsDNA molecule represented by a polymer through an artificial nano-pore in a membrane is simulated using the numerical method combining the lattice Boltzmann and Langevin molecular dynamic method. The polymer motion is represented by Langevin molecular dynamics technique while the fluid flow is taken into account by fluctuating lattice-Boltzmann method. The hydrodynamic interactions between the polymer and solvent in a confined space with a membrane having a hole are considered explicitly through the frictional and the random forces. The electric field intensity over the space is obtained from a finite difference method. Initially, the polymer is placed at one side of the space, and an electric field is applied to drive the polymer to the other side of the space through the nano-pore. In future, we plan to study the effect of the polymer size and the electric field on the electrophoretic velocity.