• Journal of the Korean Wood Science and Technology
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• 제37권5호
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• pp.465-473
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• 2009

Three failure theories were studied to evaluate the wood strength variation with grain slope. Maximum stress theory, Tsai-Hill theory and Hankinson formula were presented to hypothesize the failure of wood according to grain slope to loading direction. Red pine and Japanese larch were used as materials to simulate failure strength prediction with grain slope. Calculation of strength results was that the strength of wood drops rapidly between parallel to grain orientation (0 degree) and 15 degree grain orientation. The strength of wood with grain orientation were somewhat different at small grain angles among failure theories, and this tendency was due to tension and compression distinction, and shear accounting in each theories. For the above 45 degree grain orientation, the predicted failure strength of wood with grain variation were very close in each failure theories and were useful in assessing failure strength of wood. The applicable these theories should be considered that the wood has different behavior in tension and compression, and this lead to different strength at small grain angles in each theories. Furthermore, reconsideration is needed to assess the failure strength of wood at small grain angles in Hankinson formula and further studies are necessary to accounting for shear behavior at small grain angles.

• Geomechanics and Engineering
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• 제30권6호
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• pp.503-515
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• 2022

The permeability coefficient is an essential parameter for the study of seepage flow in fractured rock mass. This paper discusses the feasibility and application value of using readily available RQD (rock quality index) data to estimate mine water inflow and grouting quantity. Firstly, the influence of different fracture frequencies on permeability in a unit area was explored by combining numerical simulation and experiment, and the relationship between fracture frequencies and pressure and flow velocity at the monitoring point in fractured rock mass was obtained. Then, the stochastic function generation program was used to establish the flow analysis model in fractured rock mass to explore the relationship between flow velocity, pressure and analyze the universal law between fracture frequency and permeability. The concepts of fracture width and connectivity are introduced to modify the permeability calculation formula and grouting formula. Finally, based on the on-site grouting water control example, the rock mass quality index is used to estimate the mine water inflow and the grouting quantity. The results show that it is feasible to estimate the fracture frequency and then calculate the permeability coefficient by RQD. The relationship between fracture frequency and RQD is in accordance with exponential function, and the relationship between structure surface frequency and permeability is also in accordance with exponential function. The calculation results are in good agreement with the field monitoring results, which verifies the rationality of the calculation method. The relationship between the rock mass RQD index and the rock mass permeability established in this paper can be used to invert the mechanical parameters of the rock mass or to judge the permeability and safety of the rock mass by using the mechanical parameters of the rock mass, which is of great significance to the prediction of mine water inflow and the safety evaluation of water inrush disaster management.

• 한국의류학회지
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• 제35권11호
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• pp.1271-1284
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• 2011

This study improves the fitness of Air Force winter service uniforms through the development of a shirt pattern drafting method and automatic pattern drafting program for MTM production. A calculation formula is formed through a correlation analysis and regression analysis using Size Korea 2004 3D measurement data after analyzing 4 kinds of existing shirt pattern drafting methods and 3 types of shirt patterns currently used for the Air Force service uniform. The results of this study are as follows: The developed pattern drafting method has 4 parts that use calculated dimensions: neck base width, front interscye, back interscye and scye depth. Other body measuring parts that have a high correlation with calculation parts are inserted into regression analysis as independent variables to create dimension calculation formulas. The result of the final study patterns were better than existing winter service uniforms in nearly all items for the appearance evaluation and motion adaptability evaluations. The method was converted into an automatic pattern drafting program using C++ after the completion of pattern drafting method development.

• 한국지진공학회논문집
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• 제25권3호
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• pp.121-128
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• 2021

Structures of domestic nuclear power plants are designed to perform elastic behavior against beyond design earthquakes, but studies on the nonlinear behavior of structures have been insufficient since the beyond design earthquake. Accordingly, it is judged that it will be necessary to develop an evaluation method that considers the nonlinear behavioral characteristics to check the safety margin for a standard nuclear power plant structure. It is confirmed that the restoring force characteristics for each member level can be identified through the calculation formula, and the lateral stiffness for each story can also be easily calculated by JEAC 4601. In addition, as a result of applying the evaluation method of JEAC 4601 as a nonlinear restoring force model of the nuclear power plant, a certain degree of safety margin can be identified.

• Steel and Composite Structures
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• 제3권2호
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• pp.123-140
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• 2003

The importance of the research on moment-resistant properties of unstiffened tubular joints and the research background are introduced. The performed experimental research on the bending rigidity and capacity of the joints is reported. The emphasis is put on the discussion of the flexural behavior of the joints including sets of geometrical parameters of the joints and several loading combinations. Procedures and results of loading tests on four full size joints in planar KK and X configuration are described in details at first. Mechanical models are proposed to analyze the joint specimens. Three-dimensional nonlinear FE models are established and verified with the experimental results. By comparing the experimental data with the results of the analysis, it is reported reasonable to carry out the structural analysis under the assumption that the joint is fully rigidly connected, and their bending capacities can assure the strength of the members connected under certain limitation. Furthermore, a parametric formula for inplane bengding rigidity of T and Y type tubular joints is proposed on the basis of FE calculation and regression analysis. Compared with test results, it is shown that the parametric formula developed in this paper has good applicability.

• 한국태양에너지학회 논문집
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• 제34권6호
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• pp.39-47
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• 2014

Daylighting has a great effect on people inside the room. It is also closely related to the lighting energy consumption. Daylight factor(DF) is a very important index for evaluation of the daylighting in overcast sky. The objective of this study is to verify the suitability of the Tregenza's Modified Split Flux formula for the calculation of the daylight factor. We compared the daylight factors calculated by two methods; one by a measurement with 1/5 scale model and the other by the Daysim program. We used variables for verification as window wall ratios(WWR) and angles of the sky visible. As a result, daylight factor calculated by Modified Split Flux is similar to the measurement when more daylight enters the inside. And error is significantly increased when the angle of the sky visible is $50^{\circ}$.

• 한국산학기술학회논문지
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• 제15권11호
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• pp.6440-6445
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• 2014

선박 해양플랜트를 비롯한 강구조물에서는 건조중 형성된 결함이나 사용중에 가해지는 여러 가지 하중등에 의하여 균열을 비롯한 손상이 발생한다. 따라서 균열의 해석을 위하여 균열의 세기를 여러 가지 방법으로 평가하며, 파괴역학적 수법에 의한 응력확대계수 K도 그 중의 한가지 방법이다. 본 연구에서는 이러한 목적으로 사용되는 강구조물용 강재의 응력확대계수 K의 평가를 위하여 특히 CT시험편에 대하여 J 적분을 사용하여 평가를 실시하였다. CT시험편의 J 적분의 평가에는 inhouse FEM program을 사용하였으며, 859개의 node 와 1618개의 element로 해석을 실시하였다. 계산결과 본 연구에서의 해석결과는 ASTM에서 제시하는 식에 의한 K값과 99%정도의 일치도를 나타내었다. 이상으로부터 본 연구에서의 시험편에 대하여 사용한 mesh size로 충분한 정도의 균열 해석이 가능함을 알 수 있었다.

• 건축역사연구
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• 제21권2호
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• pp.37-52
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• 2012

This research has set up the fire fighting general index for Fire fighting of Crowded Wooden Building Cultural Asset which is composed of traditional wooden building instinct or complex. The results of this study are as follows. First, Fire fighting general index for crowded wooden building cultural asset, it is necessary to set fire fighting priority by considering fire risk and cultural asset characteristic and establish the system to cope with fire disaster in the most effective way by arranging facilities with restricted resource. Second, Fire risk is the index to draw fire and spread risk of cultural asset by applying index calculation processes such as fire load, burning velocity and ignition material spread characteristic to various aspects such as individual building and complex and combining their results. Cultural asset importance index consists of individual building evaluation, publicity security degree, area importance evaluation and historical landscape degree evaluation. Third, for each index combination process, weight of each index is drawn on the basis of AHP analysis result that is performed to the specialists of related fields. The formula to apply and combine it is prepared to apply the model to include meaning of each index and comparative importance degree.

• Steel and Composite Structures
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• 제37권6호
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• pp.633-647
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• 2020

This paper aims to study the seismic performance of external diaphragm connection between SST (square steel tube) column and H-shaped beam through experimental and analytical study involving finite element (FE) method and theoretical analysis. In the experimental study, three external diaphragm connection specimens with weak panel zone were tested under axial pressure on the top of the column and antisymmetric cyclic loads at the beam end to investigate the seismic performance of the panel zone. The hysteretic behavior, failure mode, stiffness and ductility of the specimens were discussed. Key point to be explored was the influence of the thickness of the steel tube flange on the shear capacity of the specimens. In the analytical study, three simplified FE models were developed to simulate the seismic behavior of the specimens for further analysis on the influence of steel tube flange. Finally, four existing calculation formulas for the shear capacity of the external diaphragm connection were evaluated through comparisons with the results of experiments and FE analysis, and application suggestions were put forward.

• 한국구조물진단유지관리공학회 논문집
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• 제25권3호
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• pp.92-99
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• 2021

건축물의 정밀안전점검 및 정밀안전진단시에는 안전등급 판정을 위해 상태평가를 실시하여야 한다. 2004년부터 정량적인 상태평가를 위해 퍼지이론을 이용한 평가방법을 도입하였고, 퍼지이론을 이용한 철근콘크리트 부재의 평가항목 간의 관계와 중요도를 도출하였다. 일반적으로 퍼지이론은 상관관계가 명확하지 않고, 모호한 표현을 처리할 때 사용되는 방법으로, 개발 당시에는 점검 및 진단 결과자료들이 부족한 상황에서 대안으로 퍼지이론을 적용하여 개발한 것으로 보인다. 따라서 실제 점검 및 진단 결과자료를 이용하여 퍼지이론을 바탕으로 도출된 평가항목 간의 관계와 중요도에 대한 검증이 필요하다. 본 연구에서는 정밀안전점검 19건과 정밀안전진단 9건의 결과와 성능점수 함수식을 이용하여 평가항목간의 상관관계를 도출하였으며, 이를 이용하여 부재의 합리적인 내구성 점수 산정식을 제시하였다.