• Title/Summary/Keyword: Natural

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The Dynamic Characteristics for Low-rise Reinforced Concrete Buildings by Vibration Measurements (진동계측에 의한 저층 철근콘크리트조 건물의 동적특성)

  • Kang, Dong-Gyun;Yoon, Sung-Won
    • Journal of Korean Association for Spatial Structures
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    • v.3 no.1 s.7
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    • pp.47-55
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    • 2003

  • This paper is concerned with the dynamic characteristics of buildings, especially with the measurement of the natural frequencies(natural periods) and the damping. Process of ambient vibration and synchronized human excitation tests for natural period and damping are given. Data from measurement on 16 reinforced concrete buildings in Seoul and Seoul national university of technology are given. 16 Low-rise Reinforced concrete buildings are measured for ambient vibration to obtain the vibrations characteristics. The natural periods obtained by ambient vibration measurements are compared with those of forecast model suggested by standards and foreign researchers. The natural periods show a clear dependence on building height. On the other hand, the damping ration scatter under the influence of various factors, for example, building height and natural frequency.

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Measuring calorific values of natural gases using sound velocity and thermal conductivity (천연가스 음속과 열전도도 상관식을 이용한 발열량 측정기술)

  • Lee, Ju-Haeng;Choi, Byungchul;Choi, Inchul
    • 한국연소학회:학술대회논문집
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    • 2015.12a
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    • pp.57-59
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    • 2015

  • A method to measure heating value of natural gas using sound velocity and thermal conductivity is proposed to solve the low heating value issues of imported natural gas in South Korea. Natural gas generally consists of methane, butane, ethane, and inert gases. Heating value changes as the gas material properties, such as density, wobbe index, etc., varies. It is highly important to measure heating values of natural gases accurately because measuring the heating value depends on the given natural gases' components. Therefore, sound velocity and thermal conductivity is measured to estimate indirectly heating value of Natural gas with their changed components.

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Physico-Chemical Properties of Natural Zeolite -On the Zeolite from Kampo Area- (천연 제올라이트의 물리화학적 성질 -경북 감포산 제올라이트에 관하여-)

  • 조승래;이홍기;이주성;심미자;김상욱
    • Journal of the Korean institute of surface engineering
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    • v.26 no.6
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    • pp.334-340
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    • 1993

  • The physico-chemical properties and characteristics after thermal treatment of natural zeolite from Kampo area were studied. The physico-chemical properties of natural zeolite were studied by investigating chemical composition, x-ray diffraction pattern(XRD), scanning electronic microscope(SEM), infrared spec-tra(IR), thermal analysis(TA), and cation exchange capacity(C.E.C.), and the characteristics of natural zeo-lite after thermal treatment from $400^{\circ}C$ to $900^{\circ}C$ were compared with the natural zeolite. This study showed that clinoptilolite was the predominant costituent in natural zeolite, and the natural zeolite contained a little amount of quartz and feldspar as impurities. Zeolite mineral was seen to develop slowly by the natural alternation of volcanic ash considering the almost amorphous crystal structure. The more temperature of ther-mal treatment increased, the more adsorption capacity decreased, considering the fact that the hydroxy peak diminished on infrared spectra, and that cation exchange capacity also decreased distinctly.

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