• 대한수학회지
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• 제32권3호
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• pp.447-459
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• 1995

A fundamental problem is to construct linear systems with given transfer functions. This problem has a well known solution for unitary linear systems whose state spaces and coefficient spaces are Hilbert spaces. The solution is due independently to B. Sz.-Nagy and C. Foias [15] and to L. de Branges and J. Ball and N. Cohen [4]. Such a linear system is essentially uniquely determined by its transfer function. The de Branges-Rovnyak construction makes use of the theory of square summable power series with coefficients in a Hilbert space. The construction also applies when the coefficient space is a Krein space [7].

• 한국주거학회논문집
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• 제14권4호
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• pp.39-48
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• 2003

The purpose of this study was to analyze the changes of floor plans in the entry and transfer spaces of single detached houses. The sample size was 185 households in Chungju, Jechon and Wonju Which are small cities in the central region of Korea. The results of the study are as follows: Firstly, the approach and transfer spaces show various changes and those are important factors which symbolize the housing plane typology transformations of the research areas. Secondly, the approach direction to the indoor space was more adopted a front approach in 1960's and 1970's, it is a side approach in 1980's, and a back side approach in 1990's. Thirdly, as the stage of the transfer space increased, the detached house planes have been changing to the direction, the depth of space comes to be deep, spatial function to be fixed, and privacy of bed rooms to be increased.

• 정보처리학회논문지A
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• 제14A권2호
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• pp.85-90
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• 2007

본 논문은 애니메이터로 하여금 표정공간으로부터 임의의 표정상태 수 개를 선택하도록 하면, 최적의 표정전이경로를 자동적으로 설정하도록 해줌으로써, 얼굴 표정 애니메이션을 실시간적으로 생성하거나 표정 제어가 가능하도록 하기 위한 기법을 기술한다. 표정공간은 약 2500개의 얼굴 표정상태 간의 거리를 구하고, 다차원 스케일링 기법을 사용하여 2차원 평면에 분포시킴으로서 형성된다. 표정공간에서 최적의 표정전이경로를 설정하기 위해서는 임의의 얼굴 표정상태를 기준으로 사분면처럼 4개의 영역으로 나눈다. 그리고 각 영역별로 최단거리에 존재하는 열굴 표정상태를 결정하고, 그 중에서 가장 가까운 얼굴 표정상태를 선택하여 전이시키고, 전이가 끊어진 얼굴 표정상태에서는 두 번째, 세 번째 혹은 네 번째로 가까운 얼굴 표정상태를 선택하여 순서대로 전이시킴으로써 완전한 표정전이경로가 결정된다. 그리고 애니메이터가 표정공간에서 대표적인 수 개의 표정상태만을 선택해주면 시스템은 자동적으로 최적의 표정전이경로를 설정하여 준다. 본 논문은 애니메이터들로 하여금 본 시스템을 사용하여 얼굴 애니메이션을 생성하거나 표정 제어를 수행하도록 하였으며, 그 결과를 평가한다.

• 한국광학회지
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• 제9권6호
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• pp.396-402
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• 1998

광학계의 결상성능평가는 optical transfer function(OTF)을 측정하는 것이 표준적인 방법으로 사용되고 있다. 그러나, 대량 생산되는 광학계의 경우에서는 측정의 편리함 때문에 test pattern을 투영하여 contrast를 검사하는 방법도 많이 사용되고 있다. 본 연구에서는 회절결상이론을 사용하여 주기적 line-space pattern에 대한 contrast transfer function(CTF)을 계산하는 프로그램을 개발하고, C­계수와 Zernike 다항식으로 표현되는 3차 파면수차에 의한 광학계의 modulation transfer function (MTF)과 CTF 변화를 비교, 분석하였다.

• Nuclear Engineering and Technology
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• 제41권9호
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• pp.1143-1156
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• 2009

The SPACE code that is based on a multi-dimensional two-fluid, three-field model is under development for licensing purposes of pressurized water reactors in Korea. Among the participating research and industrial organizations, KAERI is in charge of developing the physical models and correlation packages for the constitutive equations. This paper introduces a developed wall-to-fluid heat transfer package for the SPACE code. The wall-to-fluid heat transfer package consists of twelve heat transfer subregions. For each sub-region, the models in the existing safety analysis codes and the leading models in literature have been peer reviewed in order to determine the best models which can easily be applicable to the SPACE code. Hence a wall-to-fluid heat transfer region selection map has been developed according to the non-condensable gas quality, void fraction, degree of subcooling, and wall temperature. Furthermore, a partitioning methodology which can take into account the split heat flux to the continuous liquid, entrained droplet, and vapor fields is proposed to comply fully with the three-field formulation of the SPACE code. The developed wall-to-fluid heat transfer package has been pre-tested by varying the independent parameters within the application range of the selected correlations. The smoothness between two adjacent heat transfer regimes has also been investigated. More detailed verification work on the developed wall-to-fluid heat transfer package will be carried out when the coupling of a hydraulic solver with the constitutive equations is brought to completion.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.574-579
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• 1995

Saturated boiling heat transfer experiment in a hemispherical narrow space is conducted using Freon-113 to investigate an additional heat removal capability through a hypothetical gap between lower head and degraded core. The narrow space of 1mm consists of a 124mm diameter heated stainless steel hemisphere and a glass outer vessel. Within the hemispherical narrow space large coalesced bubbles are produced and these bubbles rise in random direction, causing liquid flow in from the opposite side to fill the region. Such flow in random direction makes the flow field in the narrow space very chaotic and thus enhance heat transfer. The heat transfer coefficient is higher at lower angle and at higher heat flux. The present study shows that the liquid from upper region can effectively penetrate into the gap and augment the heat removal capability through tile gap.

• 한국주거학회논문집
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• 제15권3호
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• pp.93-99
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• 2004

This study was conducted to estimate the solar energy, as an alternative energy evaluating an effect of solar radiation on indoor space of residential building. The basic data of solar radiation which is useful for architectural design was suggested using theoretical and experimental analysis. Accordingly, this study was carried out measuring the solar energy using Explicit Method. These results were compared with the results using steady state heat transfer method. The results of this study are summarized as follows; Based on the results using Explicit Method and steady state heat transfer on the indoor space of building, it was shown that an analysis on heat transfer using Explicit Method is more sensitive to the outdoor environmental changes. The results using Explicit Method to analysis and evaluate the solar radiation should be used for residential building design.

• 한국수소및신에너지학회논문집
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• 제32권1호
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• pp.63-67
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• 2021

Accurate measurements of the heat transfer coefficients of concentric annular space for the test section is important to measure the tube-side heat transfer coefficients of working fluids. This paper presents the annular side heat transfer coefficients of concentric annuli with variation of tube diameter ratios using Wilson plot method. The test facility has a straight, horizontal test section with an active length of 3.0 m. Inner/outer diameters of test tubes are 7.0/7.5 and 8.0/8.56 mm, respectively. An outer diameter of annulus side is 16.0 mm. The test results show that convective heat transfer coefficients in annuli increase with annular diameter ratio. The correlations for convective heat transfer coefficients in annuli are also developed.

• 한국항공우주학회지
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• 제40권1호
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• pp.69-77
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• 2012

1990년대 들어 달 탐사가 재개 된 후 2000년대부터 세계우주선진국들을 중심으로 달을 선점하기 위한 치열한 달 탐사 경쟁이 벌어지고 있다. 우리나라도 2020년경 자력 달 탐사를 목표로 선행연구를 수행 중에 있다. 본 연구에서는 한국형 달 탐사를 대비하여 지구에서 달로 가는 천이궤적 중 연료 최소화를 위해 다양한 천이궤적의 Delt-V를 비교 분석하였다. 시뮬레이션을 통해 한국형 달 탐사에 가장 적합한 지구-달 천이궤적을 확인하였으며, 실제 한국형 달 탐사시 유용한 자료로 사용될 것이다.

• Journal of Astronomy and Space Sciences
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• 제31권1호
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• pp.51-61
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• 2014

In this work, the preliminary analysis on both the tracking schedule and measurements characteristics for the spacecraft on the phase of lunar transfer and capture is performed. To analyze both the tracking schedule and measurements characteristics, lunar transfer and capture phases' optimized trajectories are directly adapted from former research, and eleven ground tracking facilities (three Deep Space Network sties, seven Near Earth Network sites, one Daejeon site) are assumed to support the mission. Under these conceptual mission scenarios, detailed tracking schedules and expected measurement characteristics during critical maneuvers (Trans Lunar Injection, Lunar Orbit Insertion and Apoapsis Adjustment Maneuver), especially for the Deajeon station, are successfully analyzed. The orders of predicted measurements' variances during lunar capture phase according to critical maneuvers are found to be within the order of mm/s for the range and micro-deg/s for the angular measurements rates which are in good agreement with the recommended values of typical measurement modeling accuracies for Deep Space Networks. Although preliminary navigation accuracy guidelines are provided through this work, it is expected to give more practical insights into preparing the Korea's future lunar mission, especially for developing flight dynamics subsystem.