• International Journal of Aeronautical and Space Sciences
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• 제16권4호
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• pp.624-635
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• 2015

Design space exploration has been much neglected in aircraft conceptual design phase, which often leads to a waste of time and cost in design, manufacture and operation process. It is necessary to explore design space based on operational system-of-systems (SoS) simulation during the early phase for a competitive design. This paper proposes a methodology to analyze aircraft performance parameters in four steps: combination of parameters, object analysis, operational simulation, and key-parameters analysis. Meanwhile, the design space of an unmanned aerial vehicle applied in earthquake search and rescue SoS is explored based on this methodology. The results show that applying SoS simulation into design phase has important reference value for designers on aircraft conceptual design.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2009년도 한국우주과학회보 제18권1호
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• pp.57.1-57.1
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• 2009

• 천문학논총
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• 제27권4호
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• pp.111-116
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• 2012

Far-infrared observations provide crucial data for the investigation and characterisation of the properties of dusty material in the Interstellar Medium (ISM), since most of its energy is emitted between ~ 100 and $200{\mu}m$. We present the first all-sky image from a sensitive all-sky survey using the Japanese AKARI satellite, in the wavelength range $50-180{\mu}m$. Covering > 99% of the sky in four photometric bands with four filters centred at $65{\mu}m$, $90{\mu}m$, $140{\mu}m$, and $160{\mu}m$ wavelengths, this achieved spatial resolutions from 1 to 2 arcmin and a detection limit of < 10 MJy $sr^{-1}$, with absolute and relative photometric accuracies of < 20%. All-sky images of the Galactic dust continuum emission enable astronomers to map the large-scale distribution of the diffuse ISM cirrus, to study its thermal dust temperature, emissivity and column density, and to measure the interaction of the Galactic radiation field and embedded objects with the surrounding ISM. In addition to the point source population of stars, protostars, star-forming regions, and galaxies, the high Galactic latitude sky is shown to be covered with a diffuse filamentary-web of dusty emission that traces the potential sites of high latitude star formation. We show that the temperature of dust particles in thermal equilibrium with the ambient interstellar radiation field can be estimated by using $90{\mu}m$, $140{\mu}m$, and $160{\mu}m$ data. The FIR AKARI full-sky maps provide a rich new data set within which astronomers can investigate the distribution of interstellar matter throughout our Galaxy, and beyond.

• 시스템엔지니어링학술지
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• 제11권2호
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• pp.61-73
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• 2015

The early-phase naval ship design demands requirements synthesis rather than design synthesis, which conducts engineering design for several domains on a detailed level. Requirements synthesis focuses on creating a balanced set of required operational capabilities satisfying user's needs and concept of operations. Requirements are evolved from capability based languages to function based language by statistical exploration and engineering design which are derived in the following order: concept alternative, concept baseline, initial baseline and functional baseline. The early-phase naval ship design process can be divided into three passes: concept definition, concept exploration and concept development. Main activities and outcomes in each pass are shortly presented. Concept definition is the first important step that produces a concept baseline through extensive design space exploration promptly. Design space exploration applies a statistical approach to explore design trends of existing ships and produce feasible design range corresponding to concept alternative. It further helps naval systems engineers and operational researchers by inducing useful responses to user and stakeholders' questions at a sufficient degree of confidence and success in the very early ship design. The focus of this paper is on the flow of design space exploration, and its application to a high-speed patrol craft. The views expressed in this paper are those of the authors, and do not reflect the official policy or rule of the Navy.

• 천문학논총
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• 제32권1호
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• pp.213-217
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• 2017

The recent updates of the North Ecliptic Pole deep ($0.5deg^2$, NEP-Deep) multi-wavelength survey covering from X-ray to radio-wave is presented. The NEP-Deep provides us with several thousands of $15{\mu}m$ or $18{\mu}m$ selected galaxies, which is the largest sample ever made at these wavelengths. A continuous filter coverage in the mid-infrared wavelength (7, 9, 11, 15, 18, and 24 µm) is unique and vital to diagnose the contributions from starbursts and AGNs in the galaxies out to z=2. The new goal of the project is to resolve the nature of the cosmic star formation history at the violent epoch (e.g. z=1-2), and to find a clue to understand its decline from z=1 to present universe by utilizing the unique power of the multiwavelength survey. The progress in this context is briefly mentioned.

• 천문학논총
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• 제27권4호
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• pp.363-365
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• 2012

We report a search for fluctuations of the sky brightness toward the North Ecliptic Pole with AKARI, at 2.4, 3.2, and $4.1{\mu}m$. The stacked images with a diameter of 10 arcminutes of the AKARI-Monitor Field show a spatial structure on the scale of a few hundred arcseconds. A power spectrum analysis shows that there is a significant excess fluctuation at angular scales larger than 100 arcseconds that cannot be explained by zodiacal light, diffuse Galactic light, shot noise of faint galaxies, or clustering of low-redshift galaxies. These findings indicate that the detected fluctuation could be attributed to the first stars of the universe, i.e., Population III stars.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.306-313
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• 2004

The microwave discharge ion engine generates plasmas of both the main ion source and the neutralizer using 4㎓ microwave without discharge electrodes and hollow cathodes, so that long life and durability against oxygen and air are expected. The MUSES-C “HAYABUSA” asteroid explorer installing four microwave discharge ion engines “$\mu$10s” was launched into deep space by M-V rocket No.5 on May 9, 2003. After vacuum exposure and several runs of baking for reduction of residual gas the ion engine system established the continuous acceleration of the spacecraft toward the asteroid “ITOKAWA”. The Doppler shift measurement of the communication microwave revealed the performance of ion engines, which is 8mN thrust force for a single unit with 3,200sec specific impulse at 23mN/㎾ thrust power ratio. At the end of 2003 the accumulated operational time exceeded 8,000 hour and unit. HAYABUSA will execute the Earth swing-by on June 2004 and arrive at the asteroid in 2005 and return to Earth in 2007.

• 한국항공우주학회지
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• 제39권1호
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• pp.63-68
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• 2011

세계 각국은 달 탐사에 대한 연구를 활발하게 진행하고 있으며 우리나라에서도 달 탐사 임무를 수행하기 위한 기초연구가 이루어지고 있다. 성공적인 달 탐사 임무 수행을 위한 통신 시스템의 개발은 달 탐사 프로젝트에 있어서 중요한 부분이다. 본 논문에서는 기저대역 프로세서 개발을 위한 기본 연구로써 달 탐사 통신 링크에 대한 요구조건 분석을 바탕으로 DSP 프로토타입 시스템을 설계하고 심우주 통신을 위한 국제 표준을 고려하여 각 핵심 모듈을 구현한다. DSP 프로토타입의 비트 오류 확률 값을 컴퓨터 시뮬레이션 결과와 비교함으로써 검증한다.

• 천문학회보
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• 제42권2호
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• pp.74.2-74.2
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• 2017

Faint quasars are important to test the possibility that quasars are the main contributor to the cosmic reionization. However, it has been difficult to find faint quasars due to the lack of deep, wide-field imaging data. In this poster, we present our efforts to find faint quasars in the ELAIS-N1 field through the deep data (iAB ~ 25) obtained by the Subaru Hyper Suprime-Cam (HSC) Strategic Program survey. To select reliable quasar candidate, we also use the near-infrared (NIR) data of the Infrared Medium-deep Survey (IMS) and the UKIRT Infrared Deep Sky Survey (UKIDSS) - Deep Extragalactic Survey (DXS). Using multiple-band color cuts, we select high redshift quasar candidates. To confirm them as high redshift quasars, candidates are observed by the SED camera for QUasars in EArly uNiverse (SQUEAN) instrument in several medium band filters that can sample the redshifted Lyman break efficiency. The quasar sample will be used to study the growth of BH and stellar mass, the relation between the quasar activity and the host galaxy, and their contribution to the cosmic re-ionization.

• 우주기술과 응용
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• 제3권1호
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• pp.44-57
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• 2023

상호 호혜적으로 진행되는 심우주 탐사 시장에서 우리나라와 같은 심우주 탐사의 후발주자가 심우주 탐사선진국과 빠르게 보조를 맞추기 위해서는 개발기간과 비용을 줄일 수 있는 표준 심우주 탐사선 모델 도출이 필수적이다. 본 논문에서는 다양한 심우주 탐사선에 요구되는 공통설계를 기반으로 하는 표준 심우주탐사선 기본형, 경량형, 및 확장형에 대한 개념 및 형상을 새롭게 제시하였다. 제시된 형상은 모듈화 설계를 바탕으로 하여 확장성 및 설계/구현 효율성을 높였다. 그리고, 표준 심우주 탐사선의 3가지 형태에 적용 가능한 경량화/확장성을 기반으로 하는 전기시스템 설계에 대해서도 기술하였다.