• 제목/요약/키워드: structural break

검색결과 165건 처리시간 0.024초

인삼재배 해가림시설의 기상재해와 구조개선대책 (Structural Improvement of the Shading Structures against Meteorological Disasters in Ginseng Fields)

  • 남상운
    • 한국농공학회지
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    • 제45권4호
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    • pp.98-106
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    • 2003
  • In order to set up structural improvement strategy against meteorological disasters of the shading structures in ginseng fields, structural safety analyses as well as some case studies of structural damage patterns were carried out. According to the results of structural safety analysis, allowable safe snow depth for type B(wood frame with single span) was 25.9 cm, and those for type A(wood frame with multi span) and type C and D (steel frame with multi span) were 17.6 cm, 25.8 cm, and 20.0 cm respectively. So types of shading structures should be selected according to the regional design snow depth. An experiential example study on meteorological disasters indicated that a strong wind damage was experienced once every 20 years, and a heavy snow damage once every 9.5 years. The most serious disasters were caused by heavy snow and it was found that a half break and complete collapse of structures were experienced by about 70% of snow damage. In addition to maintenance, repair and reinforcement, it is also recommended that improved model of shading structures for ginseng cultivation should be developed as a long term countermeasures against meteorological disasters.

Are Precious Metals Hedge Against Financial and Economic Variables?: Evidence from Cointegration Tests

  • YAQOOB, Tanzeela;IQBAL, Javed
    • The Journal of Asian Finance, Economics and Business
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    • 제8권1호
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    • pp.81-91
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    • 2021
  • This paper investigates the long run hedging ability of precious metals against the risks associated with adverse conditions of economic and financial variables for Pakistan, the USA, China, and India. Monthly data of gold, silver, platinum, stock returns, exchange rate, industrial production, and inflation was collected for the selected economies. Saikkonen and Lutkepohl (2002) unit root test was employed to access the unit root properties of the data series and identify the break dates. Furthermore, this study used the Johansen cointegration test with and without structural breaks to identify the long-run relationship between metals prices and different financial and economic variables. The findings suggest that the time series under study have unit root problem at level with and without structural breaks. Without considering structural breaks, the Johansen trace test indicates that in Pakistan and China, gold, silver, and platinum hold a cointegrating relationship with macroeconomic and financial variables. For the US, gold indicates cointegration which supports the hedging ability of gold against inflation, stock, and industrial production in the long run. The results of the cointegration test after incorporating the structural breaks provide even stronger evidence of the long-run relationship of precious metals and consumer prices, exchange rate, and stock prices.

피로 균열 형상 진전의 수치 모델링 기법에 관한 연구 (A Numeric Modelling Technique for the Shape Development of Fatigue Crack)

  • 한문식
    • 한국정밀공학회지
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    • 제16권2호통권95호
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    • pp.225-233
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    • 1999
  • This paper describes a versatile finite element technique which has been used to investigate of wide range of structural defects of practical importance. The procedure automatically remeshes the three-dimensional finite element model during the stages of crack growth. Problems analyzed to date include the surface cracks in leak-before-break situations, the development of quarter-elliptical corner defects, planar semi-elliptical surface defects and the fatigue growth of defects.

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시계열 자료에 나타나는 장기 기억 속성에 대한 추정 및 검정 :NYSE composite index에 대한 실증분석

  • 남재우;이회경
    • 한국경영과학회:학술대회논문집
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    • 한국경영과학회 1998년도 추계학술대회 논문집
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    • pp.271-274
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    • 1998
  • In this paper we examine long-term memory of the financial time-series by employing the R/S analysis, the Hurst exponent estimation, and the modified R/S analysis. The null hypothesis of white-noise is tested using the NYSE daily indexes from January 1966 to July 1998, and the results show that long-range dependence exists before the apparent structural break of the Black Monday in 1987.

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피로 하중하에서의 복수표면크랙진전에 관한 수치시뮬레이션 (Numerical Simulation of Fatigue Growth of Multiple Surface Crack under Fatigue Load)

  • 한문식
    • 한국자동차공학회논문집
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    • 제10권6호
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    • pp.133-141
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    • 2002
  • This paper describes a versatile finite element technique which has been used to investigate wide range of structural defects of practical importance. The procedure automatically remeshes the three-dimensional finite element model during the stages of crack growth. Problems include the surface cracks in leak-before-break situations, the shape development of multiple surface defects.

원전 엘보우의 성능기반 안전여유도 분석 (Investigation of the Performance Based Structural Safety Factor of Elbows in Nuclear Power Plants)

  • 이성호;박치용;박재학
    • 대한기계학회논문집A
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    • 제33권8호
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    • pp.826-831
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    • 2009
  • The piping systems in nuclear power plant are composed of various typed pipes such as straight, elbow pipe, branch and reducer etc. The elbow is connected from straight pipe to another pipes in order to establish the complicated piping system. Elbow is one of very important components considering management of wall thinning degradation. It is however applied by various loads such as system pressure, earthquake, postulated break loading and many transient loads, which provoke simply the internal pressure, bending and torsional stress. In this study, firstly pipes in the secondary system of the nuclear power plant are classified as pipe size and type for selecting the investigating range. Next, a large number of finite element analysis considering the all typed dimensions of commercial pipe has been performed to find out the behavior of TES(twice elastic slop) plastic load of elbows, which is based on evaluation of the structural safety factor. Finally performance based structural safety factor was investigated comparing with maximum allowable load by construction code.

유체-구조물 상호작용이 원자로내부구조물의 동적응답에 미치는 영향 (The Effect of Fluid-Structure Interaction on the Dynamic Response of Reactor Internals)

  • 정명조;박찬국;황원걸
    • 전산구조공학
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    • 제6권4호
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    • pp.73-82
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    • 1993
  • 원자로내부구조물은 유체속에 잠겨있기 때문에 동적해석시 이의 영향을 고려해야한다. 본 논문에서는 지진 및 배관파단에 대한 원자로내부구조물의 동적해석을 위한 비선형해석모델을 제시하였고 유체-구조물 상호작용의 효과를 고려하는 방법에 대하여 설명하였다. 실제 해석을 통하여 유체-구조물 상호작용이 원자로내부구조물의 응답에 미치는 영향을 조사한 결과 지진해석시에는 유체-구조물 상호작용을 나타내는 hydrodynamic coupling항이 첨가됨으로써 높은 응답이 나왔으나, 배관파단시에는 이와 반대의 결과가 나왔다.

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인삼 제배 시설의 기상재해 사례 및 구조 안전성 검토 (Case Studies of Meteorological Disasters and Structural Safety Test of Ginseng Houses)

  • 남상운
    • 한국농공학회:학술대회논문집
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    • 한국농공학회 2003년도 학술발표논문집
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    • pp.339-342
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    • 2003
  • According to the results of structural safety analysis, allowable safe snow depth for type B(wood frame with single span) was 25.9cm, and those for type A(wood frame with multi span) and type C and D (steel frame with multi span) were 17.6cm, 25.8cm, and 20.0cm respectively. An experiential example study on meteorological disasters indicated that a strong wind damage was experienced once every 20 years, and a heavy snow damage once every 9.5 years. The most serious disaster was a heavy snow and it was found that a half break or complete collapse of structures were experienced by about 70% of farmhouses.

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자기유도현상을 이용한 철근 응력측정 (Stress Measurement of Steel Bar Using Magnetoelasticity)

  • 임홍철;조영식
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2006년도 정기 학술대회 논문집
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    • pp.77-81
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    • 2006
  • An attempt has been made to measure existing steel stress using magnetoelasticity. A device has been developed and used for the measurement of magnetism in response to the deformation of a steel bar. The proposed technique can be used for the assessment of existing reinforced concrete structures by the measurements of steel stress embedded inside concrete. A traditional technique requires to break the existing steel bar to measure existing strain. However, the proposed technique is developed to measure the stress without damaging the steel bar. A successful application of magnetoelasticity depends on the establishment of relationship between elastic and magnetic response due to loading. To investigate the correlation between the two, steel bars are loaded in tension under uniaxial loading while the magnetic reading is recorded. Based on the test results, equations are suggested to predict stress for steel bars with different diameters.

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Dynamic Relationship between Stock Prices and Exchange Rates: Evidence from Chinese Stock Markets

  • Lee, Jung Wan;Zhao, Tianyuan Frederic
    • The Journal of Asian Finance, Economics and Business
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    • 제1권1호
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    • pp.5-14
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    • 2014
  • This paper empirically examines the short-run and long-run causal relationship between stock market prices and exchange rates in Chinese stock markets using monthly data from January 2002 to December 2012 retrieved from the National Bureau of Statistics of the People's Republic of China. Unit root, cointegration tests, vector error correction estimates, block exogeneity Wald tests, impulse responses, variance decomposition techniques and structural break tests are employed. This study found 1) long-run causality from exchange rates to stock prices in Chinese stock markets and 2) short-run causality from Japanese yen and Korean won exchange rates to stock prices in the Shanghai Stock Exchange strongly prevails while in the Shenzhen Stock Exchange weakly prevails. The impact of the global financial crisis from 2007 to 2009 on Chinese stock markets was insignificant.