Almost all buildings and infrastructures made of advanced composite materials are fabricated without proper design. Unlike airplanes or automobiles, prototype test is impossible. One cannot destroy 10 story buildings or 100-meter long span bridges. People try to build 100-story buildings or several thousand meter long span bridges. In order to realize "composites in construction", the following subjects must be studied in detail, for his design. Simple method of analysis, Folded plate theory, Size effects in failure, and Critical natural frequency. Unlike the design procedure with conventional materials, his design should include material design, selection of manufacturing methods, and quality control methods, in addition to the fabrication method. In this paper, folded plate theory are presented for practicing engineers.

In this paper, the method of vibration analysis for calculating the natural frequency is presented. This method is a simple but exact method of calculating natural frequencies corresponding to the modes of vibration for the cantilevered composite materials conical beam. The influence of natural frequency of the cantilevered composite materials conical beam is presented. This method may be extended to stability analysis of complex structureal elements.

The purpose of this paper is to demonstrate to the practicing engineers, how to apply the advanced composite materials theory to the slab bridges. For general construction material used, there is certain theoretical limit in sizes. For super slab bridges construction, the reduction in panel weight is the first step to take in order to break such size limits. For a typical slab bridges panel, both concrete and advanced composite sandwich panels are considered. The concrete panel is treated as a special orthotropic plate. Advanced composite sandwich panels are considered as a self-weights less than one tenth of that of concrete panel, with deflections less than that of the concrete panel. This conclusion gives good guide line for design of the light weight of slab bridges.

1990년대 초부터 대규모 상업적 시설원예의 현대화 및 기업화 진행에 따라 현재 국내 시설원예 재배면적의 규모는 중국에 이어 일본, 스페인과 함께 2위를 차지하고 있다. 원예시설에 대한 안정적이고 합리적인 설계가 주요 관심사로 대두된 가운데, 특히 온실의 경우 일반적인 건축물보다 낮은 안전율로 설계가 이루어지므로 풍하중에 대하여 취약한 경량 구조물로 간주되고 있다. 최근 최대순간풍속이 40~60m/s에 다다르는 대형 태풍 및 강풍이 빈번하게 발생하고 있으며 이로 인한 농촌 시설물의 피해 규모 또한 증가하고 있다. 그러나, 국내에 활용되고 있는 온실설계기준의 경우 연구기관별로 혼재하고 있으며 대부분 해외자료를 근거로 작성된 것으로 국내온실에 적합한 설계기준의 마련이 시급한 실정이다. 따라서, 본 연구에서는 온실의 안정성 확보를 위한 설계기준을 위한 기초자료를 확보하기 위하여 풍동실험을 통해 국내 대표적인 복숭아형 온실을 대상으로 지붕곡률에 따른 풍압계수 및 국부풍압계수를 평가·제시하였다.

The special orthotropic plate theory is used for analysis of panels made of plate girders and cross beams. The cross-sections of cross-beams are WF types. The result is compared with that of the beam theory. According to the numerical examination given in this paper, the result by the plate theory is 2.43 times stiffer than that of beam theory.

최근 지하철 역사 내의 사고위험을 줄이기 위해 승강장에 스크린도어(PSD; Platform Screen Door)를 설치하는 사례가 늘고 있다. 일반적으로 지하철역사와 같이 폐쇄된 공간에 있어서 유동장의 해석 및 예측은 전산유체해석 (CFD: Computational Fluid Dynamics)을 주로 사용한다. 그러나, CFD는 실제로 열차가 주행할 때에 발생하는 비정상적(unsteady)인 유동장의 3차원적인 해석에는 승강장의 세부적인 형태의 모델링이 어렵기 때문에 어느 정도의 한계가 있다. 따라서, 본 연구에서는 밀폐형 스크린도어가 설치된 지하승강장을 대상으로 직통열차에 의한 스크린도어 및 승강장 천장마감재에 작용하는 풍압을 계측하였다. 계측된 풍압으로부터 스크린도어의 구조안전성을 위한 설계풍압을 결정하고, 승강장 내부의 천장마감재에 작용하는 풍압을 평가하여 승강장의 안전한 풍환경을 확보하는데 기초적인 자료를 제시하였다.

본 논문은 고층건축물의 비틀림방향 응답을 평가하기 위하여 필요한 변동비틀림모멘트계수와 변동비틀림모멘트의 파워스펙트럼밀도계수의 경험식을 제안한 연구이다. 이러한 경험식을 제안하기 위하여, 다양한 형상비와 변장비를 가진 27개의 각주형 모형을 제작한 후 노풍도을 다양하게 변화시켜 풍력실험 을 실시하였다. 본 논문에서 비틀림방향 변동풍력의 경험식은 주로 건물의 노풍도와 형상비 그리고 변장비에 의하여 분석되어졌다.

본 연구는 고층건축물의 비틀림방향 응답을 평가하기 위하여 필요한 변동비틀림모멘트계수와 변동비틀림모멘트의 파워스펙트럼밀도의 특성을 확인하는데 목적이 있다. 이러한 특성들을 평가하기 위하여, 다양한 형상비와 변장비를 가진 52개 형상의 공탄성 각주형 모형을 제작한 후 노풍도를 다양하게 변화시켜 풍동실험을 실시하였다. 본 논문에서는 비틀림방향의 변동풍력의 특성을 간단히 설명하였다. 그리 고 그 결과는 대부분 건물의 형상비와 변장비에 의하여 분석되었다.

We review recent observational results on early type galaxies obtained with high spatial resolution Chandra data. With its unprecedented high spatial resolution, Chandra reveals many intriguing features in early type galaxies which were not identified with the previous X-ray missions. In particular, various fine structures of the hot ISM in early type galaxies are detected, for example, X-ray cavities which are spatially coincident with radio jets/lobes, indicating the interaction between the hot ISM and radio jets. Also point sources (mostly LMXBs) are individually resolved down to Lx = a few x 10 37 erg sec-1 and it is for the first time possible to unequivocally investigate their properties and the X-ray luminosity function. After correcting for incompleteness, the XLF of LMXBs is well reproduced by a single power law with a slope of -1.0 - -1.5, which is in contrast to the previous report on the existence of the XLF break at Lx, Eddington = 2 x 10 38 erg sec-1 (i.e., Eddington luminosity of a neutron star binary). Carefully considering both detected and undetected, hidden populations of point sources we further discuss the XLF of LMXBs and the metal abundance of the hot ISM and their impact on the properties of early type galaxies.

We have developed a new device, Plate-to-CCD Convertor (PCC), to conveniently digitize photographic plates in a relatively short time without losing any plate information (Oh et al. 1995). Using this device we have performed surface photometry of 12 early type galaxies. We determined relative orientations and scales to analyze PCC images. We also determined an ellipticity, position angle of the major axis, and a4 a4 of each galaxy to quantify the distribution of surface brightness. We checked the performance and limitation of this device by comparing the PCC images with those digitized by the ST microdensitometer and those obtained with CCD observations.

We review recent systematic investigation of the X-ray spectra of early type galaxies by using the Einstein data base and present new results by the ROSAT observations. The Einstein data suggested that the galaxies with low X-ray to optical luminosity ratio may have another very soft component. ROSAT observations confirm its presence and call for further study to understand the nature of this very soft emission. The X-ray bright galaxies have emission temperature of ∼0.8keV ∼0.8keV and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.

We have systematically investigated the X-ray spectra of normal galaxies, by using the Imaging Proportional Counter (IPC) data in the Einstein data base. We employed the X-ray color-color plot as well as the standard model fitting method which requires higher signal to noise ratio. We discuss X-ray emission mechanisms in terms of their spectral properties and the signature of cooling flows which are most likely present in X-ray bright early type galaxies. On the average, fits to absorbed thermal spectra show that the X-ray emission temperature of spirals is higher than that of ellipticals. This is consistent with our understanding that accreting binaries are a major X-ray source in spirals, while extended gaseous halos are present in ellipticals. The emission temperature becomes lower with increasing X-ray to optical luminosity ratio in E and S0 galaxies. This result is what we would expect if the emission of X-ray faint early type galaxies consists of a large evolved stellar component, while the gaseous emission becomes dominant in X-ray brighter galaxies. We also find a cool, self-absorbed core in some early type galaxies, which directly indicates the presence of cooling flows in such galaxies.