• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
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• pp.34.1-34.1
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• 2009

After SNIa and WMAP observations during the last decade, the discovery of the accelerated expansion of the universe is a major challenge to particle physics and cosmology. There are currently three candidates for the dark energy which results in this accelerated expansion: $\cdot$ a non-zero cosmological constant, $\cdot$ a dynamical cosmological constant (quintessence scalar field), $\cdot$ modifications of Einstein's theory of gravity. The scalar field model like quintessence is a simple model with time-dependent w, which is generally larger than -w1. Because the different w lead to a different expansion history of the universe, the geometrical measurements of cosmic expansion through observations of SNIa, CMB and baryon acoustic oscillations (BAO) can give us tight constraints on w. One of the interesting ways to study the scalar field dark-energy models is to investigate the coupling between the dark energy and the other matter fields. In fact, a number of models which realize the interaction between dark energy and dark matter, or even visible matter, have been proposed so far. Observations of the effects of these interactions will offer an unique opportunity to detect a cosmological scalar field. In this talk, after briefly reviewing the main idea of the three possible candidates for dark energy and their cosmological phenomena, we discuss the interactinng dark-energy model, paying particular attention to the interacting mechanism between dark energy with a hot dark matter (neutrinos). In this so-called mass-varying neutrino (MVN) model, we calculate explicitly the cosmic microwave background (CMB) radiation and large-scale structure (LSS) within cosmological perturbation theory. The evolution of the mass of neutrinos is determined by the quintessence scalar field, which is responsible for the cosmic acceleration today.

• 한국항해항만학회지
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• 제34권3호
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• pp.205-211
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• 2010

밸러스트수 처리를 위한 Plasma Gun의 전기적 특성과 오존 생성에 미치는 주요 운전변수들의 영향에 관해 실험실 규모 연구를 수행하였다. 방전개시전압보다 높은 전압이 인가되면 방전이 시작되고 오존이 생성되었으며 전압이 증가함에 따라 기체로 전달되는 에너지 및 오존 농도가 거의 선형적으로 증가하였다. 오존 생성 측면에서 최적의 에너지 효율성을 얻을 수 있는 전극간 거리가 존재하였으며 실험된 장치에서는 1.95 mm의 전극간 거리에서 최적 효율이 얻어졌다. 전기에너지 특성에 미치는 내부전극 재질의 영향은 무시할만한 수준이었으나 내부전극의 전기전도도와 열전도도 차이가 오존 생성에 큰 영향을 미치는 것으로 나타났다. 일정한 Plasma Gun 구조에서 오존 생성은 기체로 전달되는 에너지밀도에 의해 중요한 영향을 받는 것으로 나타났으며 유입되는 기체의 산소함량이 증가할수록 오존 생성이 증가하는 것으로 나타났다.

• 한국실내디자인학회논문집
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• 제17권2호
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• pp.22-29
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• 2008

Johannes Vermeer is one of the masters in the 17th century Dutch Genre Painting. Genre Painting represented the mundane everyday life and humble domestic spaces of the time. It was so unique in the history of western art. Most common subjects of the medieval art had been myths, historical heroes, and the christianity up to that time. However, Dutch Genre Painting that was originated from the 16th century Flandre art has fundamentally changed perception of art. Genre Painting was related to the prosperous development of civil society and early capitalism in the Netherlands of the time. In the paintings of Vermeer, there are unique spatial characteristics. This study aims to 'spatially' analyze the representation of everyday space perceived by the painter himself. Three analytical elements were chosen: light, space, and geometry. These elements have crucial roles to construct a space together within which Vermeer tried to express his discoveries as well as perception of the world. Four paintings were selected to be further analyzed in detail: $\ulcorner$A Maid Asleep$\lrcorner$ (1656-57), $\ulcorner$The Little Street$\lrcorner$ (1658-60), $\ulcorner$The Music Lesson$\lrcorner$ (1662-1665), and $\ulcorner$Young Woman with a Water Pitcher$\lrcorner$ (1662). It has been found that there are distinct spatial aspects in his paintings: Structure of Frontal Layers, Diffusion of Light, and Subtle Geometrical Tension. It is hoped that this sort of interdisciplinary research could enrich the related studies in the field of architecture & interior design, and could help to rediscover the everyday world that we live in here and now.

• 한국통신학회논문지
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• 제28권2A호
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• pp.70-79
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• 2003

완전도체면 아래의 유전체와 측면 연마된 광섬유의 소산장 결합 및 전파특성에 대한 해석 연구 결과를 나타내었다. 두 구조에서의 전파특성과 소산장 결합 관계를 해석하기 위해 결합모드 방정식과 혼합 모드(compound-mode) 방정식을 이용하여 코아와 유전체의 굴절률 및 구조의 각 변수에 대한 특성을 나타내었다. 그리고 측면 연마된 광섬유와 완전도체면 아래의 유전체가 결합할 때 일어나는 광섬유에서의 감쇠현상을 비교하기 위하여 감쇠상수를 구하여 함께 비교하였다.

• Coupled systems mechanics
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• 제9권2호
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• pp.147-161
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• 2020

Constructive merging of "basic" systems of different behavior creates hybrid systems. In doing so, the structural elements are grouped according to the behavior in carrying the load into a geometric order that provides sufficient load and structure functionality and optimization of the material consumption. Applicable in all materializations and logical geometric forms is a transparent system suitable for the optimization of load-bearing structures. Research by individual authors gave insight into suitable system constellations from the aspect of load capacity and the approximatemethod of estimating the participation of partialstiffnesswithin the rigidity ofthe hybrid system. The obtained terms will continue to be the basisfor our own research of the influence of variable parameters on the behavior of hybrid systemsformed of glued laminated girder and cable of different geometric shapes. Previous research has shown that by applying the strut-type hybrid systems can increase the load capacity and reduce the deformability ofthe free girder.The implemented parametric analysis pointsto the basic parameterin the behavior of these systems-the rigidity ofindividual elements and the overallstiffnessofthe system.The basic idea ofpre-stressing is that, in the load system or individual load-bearing element, prior to application of the exploitation load, artificially challenge the forcesthatshould optimize the finalsystembehaviorin the overall load. Pre-stressing is possible only if the supporting system orsystem's element possesssufficientstrength orstiffness, orreaction to the imposed forces of pre-stressing. In this paper will be presented own research of the relationship of partial stiffness of strut-type hybrid systemsofdifferentgeometric forms.Conducted parametric analysisofhybridsystemswithandwithoutpre-stressing, and on the example of the glulam-steel strut-type hybrid system under realistic conditions of change in the moisture content ofthe wooden girder,resulted in accurate expressions and diagramssuitable for application in practice.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.644-648
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• 2004

In the present study were examined numerically and experimentally the off-design performance characteristics on an axisymmetric plug nozzle with variable throat area. In this nozzle concept, its throat area can be changed by translating the plug into the axial direction. First, a mixed-expansion plug nozzle, in which two expansion parts are arranged both inside and outside, was designed by means of the method of characteristics. Second, the CFD analysis was verified by the cold-flow wind tunnel test. Third, its performance characteristics were evaluated over a wide range of pressure ratio from half to double throat area through the design point, using the CFD code verified by the wind tunnel tests. It was made clear from the study that not so critical thrust efficiency losses were found and the maximum thrust efficiency loss was at most approximately 5 % under off-design conditions without external flow. This result shows that a plug nozzle can give the altitude compensation even under off-design geometry operations. However, shock waves were observed in the inner expansion part under the doubled throat area operation and thus some thermal problems may be caused on the plug surface. Furthermore, collapse of cell structure on the plug surface was observed with external flow (around Mach number 2.0) as it became lower pressure ratio below the design point and the fact may result in big efficiency loss regardless of geometrical configuration.

• Wind and Structures
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• 제25권6호
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• pp.507-535
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• 2017

In the strong wind shutdown state, the blade position significantly affects the streaming behavior and stability performance of wind turbine towers. By selecting the 3M horizontal axis wind turbine independently developed by Nanjing University of Aeronautics and Astronautics as the research object, the CFD method was adopted to simulate the flow field of the tower-blade system at eight shutdown positions within a single rotation period of blades. The effectiveness of the simulation method was validated by comparing the simulation results with standard curves. In addition, the dynamic property, aerostatic response, buckling stability and ultimate bearing capacity of the wind turbine system at different shutdown positions were calculated by using the finite element method. On this basis, the influence regularity of blade shutdown position on the wind-induced response and stability performance of wind turbine systems was derived, with the most unfavorable working conditions of wind-induced buckling failure of this type of wind turbines concluded. The research results implied that within a rotation period of the wind turbine blade, when the blade completely overlaps the tower (Working condition 1), the aerodynamic performance of the system is the poorest while the aerostatic response is relatively small. Since the influence of the structure's geometrical nonlinearity on the system wind-induced response is small, the maximum displacement only has a discrepancy of 0.04. With the blade rotating clockwise, its wind-induced stability performance presents a variation tendency of first-increase-then-decrease. Under Working condition 3, the critical instability wind speed reaches its maximum value, while the critical instability wind speed under Working condition 6 is the smallest. At the same time, the coupling effect between tower and blade leads to a reverse effect which can significantly improve the ultimate bearing capacity of the system. With the reduction of the area of tower shielded by blades, this reverse effect becomes more obvious.

• 한국측량학회지
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• 제2권1호
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• pp.54-64
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• 1984

본 연구는 지상사진기에 의한 구조물(석탑)측정에 관한 것으로서 석탑중 통일신라의 석탑인 감은사지 삼층석탑, 고선사지 삼층석탑, 불국사 삼층석탑(석가탑) 및 불상인 석굴암 본존상, 광주철조여내좌상을 대상으로 조형비를 분석하여, 조형원리에 접근하는데 의의를 갖고 있다. 등고선도와 실측치를 정밀하게 얻을 수 있었으며, 이를 바탕으로 조형비를 분석한 결과, 3재의 석탑과 2개의 불상에서 공통점을 발견할 수 있었다. 우선 석탑의 경우 옥개석폭들은 8 : 7 : 6의 비예관계로 구성되어 있었으며, 상대갑석을 밑변으로 정삼각형과 이등변 삼각형을 긋고, 그 정점사이의 거리를 반경으로 하여 정삼각형의 정점에서 원을 그리면 삼층 옥신 윗면과 일치하였고, 또 기준면으로부터 $70^{\circ}$의 2등변 삼각형을 그러는 경우 상대갑석의 끝점들을 거의 통과하며, 삼층 옥개석의 낙수면과 일치함을 알 수 있었다. 불상의 경우 양 눈사이의 중점을 중심으로 원이 성립되고, 어깨와 명치를 연장하면 무릎에 접함을 알 수 있었다.

• 한국정보통신학회논문지
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• 제18권3호
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• pp.497-502
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• 2014

본 논문에서는 지상파 디지털 TV 수신용 광대역 평면 다이폴 안테나 설계 방법에 대해 연구하였다. 코플래너 스트립으로 급전되는 평면 다이폴을 반 보우-타이형으로 소형화하였다. 급전 마이크로스트립 선로와 코플래너 스트립 선로 간의 밸런은 코플래너 스트립 중앙으로 삽입된 직사각형 패치로 구현하였다. 제안된 안테나는 이중 공진 구조로서 다이폴에 의한 공진과 밸런이 부착된 코플래너 스트립 선로에 의한 공진으로 구성된다. 제안된 안테나의 파라미터들이 안테나의 특성에 미치는 영향을 분석하고 지상파 디지털방송 주파수 대역인 470-806 MHz 대역에서 동작하도록 설계하였다. 설계된 안테나를 $95mm{\times}178mm$ 크기의 FR4 기판 상에 제작 후 실험을 통하여 연구결과의 타당성을 검증하였다.

• 정보처리학회논문지D
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• 제14D권7호
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• pp.743-752
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• 2007

단백질은 다른 물질과의 결합하여 기능을 수행하기 때문에 활성 사이트가 유사한 단백질은 유사한 기능을 가진다. 따라서 단백질의 바인딩 영역을 식별함으로써 단백질의 기능을 추론할 수 있다. 이 논문은 MCL (Markov Cluster) 알고리즘을 이용하여 단백질의 바인딩 영역을 추출하는 새로운 방법을 제시한다. 이를 위하여 단백질의 표면 잔기 거리를 나타내는 distance matrix를 생성하고, 여기에 MCL 프로세스를 적용한다. 제시한 방법을 평가하기 위해 Catalytic Site Atlas (CSA) 데이터를 사용하였다. CSA 데이터 (94개의 단일 체인 단백질)를 이용한 실험 결과, 알고리즘은 91개 단백질의 활성 사이트 주변의 바인딩 영역을 검출하였다. 이 논문은 단백질 활성 사이트를 분석하기 위한 새로운 기하학적 특징을 제시하였고, 활성 사이트와 관련이 없는 잔기를 제거함으로써 단백질 표면의 분석의 시간을 줄일 수 있는 장점이 있다.