• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.408-412
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• 2007

본 연구는 자갈하상하천에서 하상에 분포하는 입자에 작용하는 전단력을 이용하여 등가조도를 산정할 수 있는 모형을 개발하였다. 등가조도는 기존의 연구들처럼 경험적으로 특정입도에 의해 산정하지 않고 하상에 분포하는 각 입자에 작용하는 입자 전단력을 산정하고, 하상 평균전단력과의 관계로서 산정하였다. 입자 전단력은 항력을 통해 산정하였으며, 이때 항력계수는 입자의 돌출 높이를 고려할 수 있도록 하였다. 또한 입자에 부딪히는 평균유속은 수치적분을 통해 입자의 돌출 높이에 따라 가변성을 고려할 수 있도록 식으로 제시하였다. 단위면적당 입자 전단력과 하상 평균 전단력과의 관계를 통해 등가조도의 함수로서 식을 제시한 후 수치해석방법의 하나인 증분 탐색법을 통해 등가조도를 산정할 수 있도록 하였다. 그리고 산정된 등가조도를 이용하여 수위-유량관계 및 흐름저항매개변수를 산정하여 적정성을 검토하였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.3
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• pp.1-10
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• 2000

우리 나라의 주거 건물의 많은 부분을 차지하는 조적조 건물은 저층이므로 내진 설계에 대한 지침이 마련되어 있지 않다. 그러나 조적조 건물의 경우 저층이라 하더라도 구조특성상 수평하중에 대한 저항능력이 매우 약하므로 내진 설계에 대한 기준이 요구된다. 일반적으로 내진설계 시 동적 해석을 수행하면 많은 시간이 소모되므로 실무자들에게 등가정적해석법을 제시하여 내진설계 시 편의를 제공하고 있다. 그러나 저층 조적조 건물은 일반적인 건물과는 거동 특성이 다르므로 저층 조적조 건물에 적용할 수 있는 해석법을 제시하고자 한다. 본 논문에서는 개구부의 비율에 따른 조적벽의 연성도, 강도 및 고유주기를 구하여 반응수정계수와 고유주기를 비교하여 우리 나라의 조적조 건물에 적합한 반응수정계수와 고유주기 산정식을 제안하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.875-886
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• 1994

This study is to develop an advanced storm runoff analysis program which takes geomorphological characteristics of watershed into consideration in determining model parameters. Basic concept of storm runoff modelling is based upon the kinematic wave theory. And numerical solution is obtained by the characteristic curve method. The storm runoff analysis program developed by this study is composed of multiple equivalent roughness sub-basins, each of which has two equivalent catchments on both side of a stream. Because it is based upon the stream-order of the Strahler system, the equivalent catchment-stream network reflects the stochastic geomorphological characteristics in the model parameter. Applicability and reliability of the storm runoff analysis program is evidenced by model calibration and verification process utilizing geographical and hydrological data of the Bocheong-river area which is a representative watershed of IHP projects in Korea. This study will hopefully contribute to hydrological calculation essentially required to understand water quality effect caused by regional development.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.1
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• pp.47-59
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• 2012

The seismic performance of masonry-infilled frame structures, typical in school buildings, is evaluated through equivalent strut models. A bare frame model, concentric strut models and eccentric strut models with various material characteristics available in the literature are analyzed. Displacements and damage states at the performance points obtained by the capacity spectrum method show great differences among the models. Infill walls act positively in concentric strut models and negatively in eccentric strut models at the performance points for a given seismic demand. In addition, the behavior at the ultimate displacements shows considerably different strengths, inter-story drifts, and numbers and locations of damaged members among various modeling methods and material strengths.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.413-418
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• 2006

본 연구는 자갈하상을 갖는 하천에 대해 조도계수를 산정하고자 하상에 분포하는 입자에 작용하는 전단응력을 이용하여 등가조도를 산정하고 대상유량에 대해 수위를 산정할 수 있는 모형을 개발하였다. 개발된 모형의 적용성은 섬진강 하류부의 구례수위표와 송정수위표 구간에 대해 적용하였다. 그 결과 구례수위표지점에서 등가조도는 0.088m로 산정되었고, 이를 이용하여 Wark(1990)가 제시한 단위유량에 대한 연속방정식과 운동량방정식을 결합한 간단한 모형을 이용하여 각각의 대상유량에 대해 수위를 산정하였으며, 그 결과 6%이내의 오차를 보였다. 그리고 대상유량에 대해 계산된 수위를 이용한 부등류 해석을 실시하여 조도계수를 각각의 유량에 대해 산정하였다. 그 결과 관측된 수위와 계산된 수위에 의해 산정된 조도계수의 오차가 $0{\sim}0.002(6%)$의 오차를 보였고, 유량별로 조도계수를 산정할 수 있어 조도계수의 가변성도 고려할 수 있었다.

• Journal of Korean Society of Steel Construction
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• v.27 no.2
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• pp.181-193
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• 2015

High-frequency staircases are widely used nowadays to meet aesthetics and functionality needed in modern architecture. Unfortunately, no design guide is available in domestic practice to predict response or evaluate the vibration performance of high-frequency staircases. SCI-P354 published by the Steel Construction Institute of UK provides the formula for effective impulsive force. However, this formula was shown to overestimate the response of high-frequency staircases excited by fast ascending and descending over 2.2Hz pace frequency because it was developed based on the walking test in a slow pace frequency. This study proposes a semi-analytical formula to predict the response of stiff staircases based on analytical and experimental studies of response acceleration for various walking frequencies covering 1.4~4.5Hz.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.57
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• pp.65-70
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• 2006

• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.187-196
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• 2003

Today, the Working Stress Rating (WSR) is being widely used for the capacity-rating and the safety assessment of railroad steel bridges. Since it cannot incorporate the uncertainties, several studies have been carried out in order to get over the incompleteness of the conventional capacity-rating and safety assessment. A system reliability-based equivalent capacity-rating method, which can evaluate the capacity of existing bridges, has been recently proposed. For more efficient reliability analysis, probabilistic parameters of the random variables in the limit-state models should be reasonably evaluated. Especially, uncertainties for live load effects must be realistically included. In this study, an improved limit-state model was used for the system reliability-based equivalent strength method. This model can incorporate the probabilistic parameters obtained from ambient measurement data. To demonstrate the applicability of the improved system reliability-based equivalent capacity rating method, this was applied to the existing steel plate girder bridge for comparison with the conventional capacity-rating and safety assessment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9C
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• pp.743-748
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• 2008

This paper makes a research on the equivalent Wiener-Hopf equation which can obtain the coefficient of TDL filter on orthogonal input signal in terms of mean square error. Using this result, we can present the coefficient and error of TDL filter directly without inverse orthogonalization process on orthogonal input signal. We make a theoretical analysis on MMSE and show an Wiener-Hopf solution and the proposed equivalent one in mathematical example simultaneously.

• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.253-261
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• 1998

The buckling length of exterior beam-columns of the first floor in moment resisting steel frames with weak beams is uncertain when plastic hinges occur at the ends of weak beams due to seismic loads. The objective of this study is to investigate the buckling strength of concrete-filled tubular beam-columns and to suggest the reduced buckling length of them to apply to the beam-column design code. The exterior beam-columns are modelized with horizontal displacement restraint springs. Their strength and reduced buckling length are evaluated by numerical analysis.