• 제목/요약/키워드: Pebble

검색결과 189건 처리시간 0.026초

北漢江 上流 桂芳川 砂礫地 河岸植生의 遷移系列 (Vegatation seres on the pebble area at ye-bang stream bank of north han river in korea)

  • Kim, Jong-Geun;Yang-Jai Yim
    • The Korean Journal of Ecology
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    • 제14권2호
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    • pp.195-210
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    • 1991
  • The primary succession of the pebble area in gye-bang chon, an upper stream bank of north han river, was investigated by belt transect method from July to October 1990. The stsges of bare area, herbaceous pioneer, perenial herb, woody plants and pine stand were recognized from stream bank to inland. The change of the coverage in herbaceous plants increased with developing sueccessional sere but decreaser with increment of woody plants. The species sequence cyrves vs. relative coverage were geometric in pioneer stage and graduaiiy changed to lognormal y\type as the development of forest. The species diversity was highest during then woody plants stage, probably it would to be the edge effect. The soil properties were not noticeable difference between stream side and inland side. It seems that the vegetational developement was not enough to affect soil accumulation.

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MHD발전용 작동 플라즈마를 고온가열하기 위한 효율적 방안에 관한 연구 (Studies on a Effective Scheme to Obtain High Temperature Working Plasma for MHD Power Generation)

  • 김윤식;노창주;김영길;공영경;최춘성
    • 대한기계학회논문집
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    • 제17권1호
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    • pp.153-161
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    • 1993
  • 본 연구에서는 각 운전모드별 열특성을 전체적으로 고려하여 양질의 MHD발전 용 작동플라즈마를 얻기 위하여 필요한 효과적인 방책에 관하여 집중적으로 고찰하고 자 한다.

MONTE CARLO METHOD EXTENDED TO HEAT TRANSFER PROBLEMS WITH NON-CONSTANT TEMPERATURE AND CONVECTION BOUNDARY CONDITIONS

  • Cho, Bum-Hee;Cho, Nam-Zin
    • Nuclear Engineering and Technology
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    • 제42권1호
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    • pp.65-72
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    • 2010
  • The Monte Carlo method for solving heat conduction problems [1-3] is extended for non-constant temperature boundary conditions in this study. The new method can treat problems with any given non-constant boundary temperatures, including heat convection problems with non-constant fluid bulk temperature. A set of problems, particularly the heat transfer problem in a pebble fuel, is analyzed by this new method. In addition, a new method to reduce the statistical errors in kernel fuel regions is introduced when the Monte Carlo method is applied to a pebble fuel.

공기식 태양열 난방계통의 성능실험 (Performance Tests on an Air Solar Heating System)

  • 남평우;차종희
    • 대한설비공학회지:설비저널
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    • 제8권2호
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    • pp.81-88
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    • 1979
  • The performance of air type solar heating system has been investigated for a system which has been operating continuously for two years. Design factors of a collector, such as the effective transmittance-absorptance and heat transfer factor were also determined experimentally. The flat plate collector is fabricated from steel sheet metal with two sealed glass covers. Solar heat is stored in a pebble bed of primarily granitic rock approximately 20-40 mm in diameter. The system is controled by automatically driven motors and dampers. The ratio of useful collected solar heat divided by the total solar radiation on the collector dropped was the range of 35 to 42 percent in monthly average. As it result, the air system was found fairly competitive with the water system, however, the heat supply from storage was limited because of using the pebble as the heat storage media.

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옥천대(沃天帶)의 변형특성(變形特性)과 그 형성(形成) 과정(過程) -충북(忠北) 남서단(南西端)을 예(例)로 하여- (The Deformation Properties and their Formative Processes in Ogcheon Terrain around Ogcheon Town, North Chungcheong Province, Korea)

  • 이병주;박봉순
    • 자원환경지질
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    • 제16권2호
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    • pp.111-123
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    • 1983
  • The studied area is situated in tho southern part of the Ogcheon fold belt, where the "Ogcheon Group" is widespread with Jurassic and Cretaceous intrusions. The regional stratigraphy may be divided into three formations, the lower pebble bearing phyllitic, the middle dark grey phyllitic, and the upper black phyllitic formations. For the purposes of the present study, the area has been partitioned to three structural subareas based on major fold axes and fault line. The main subjects of the research have been discussed from two different points, multiple deformation and minor-micro fold styles. The former is analyzed by pebble elongation, folding and lineation in a pebbly formation as well as schistosity, crenulation cleavage and crenulated lineation in the phyllitic formation. The later describes the characteristic features of fold style in each formation and structural subarea. Although minor fold axes within broad pelitic rocks usually tend to trend northeast and to plunge northward, most of these were probably formed by two stages, first a similar fold phase and second a kink fold phase. Measured structural elements indicate that crenulation cleavage in phyllite formed parallel to fold axes of folded pebble followed a NE phase of first deformation and a fold axes of pebbles diagonal to bedding of phyllite are represented by a NW phase of a second deformation. Microscopically, quartz and mica grains form a micro fold enabling one to establish tectonic levels which occur in different deformation modes in each stratigraphic sequence. Microtextures such as crenulation cleavage, kink band, aggregate band of mica and pressure shadows of porphyroblast of quartz related to qarnet and staurolite may suggest the time relation of crystallization and tectonism. The result of this study may conform that three deformation phase, NE first phase-NE second phase-NW phase, occurred in the area.

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