• 한국재난정보학회 논문집
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• 제9권3호
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• pp.324-331
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• 2013

강바닥판 교면포장의 고정하중 감소와 내구성 확보를 위해 사용되는 에폭시 아스팔트 콘크리트는 2액 반응형 재료로서 온도와 시간에 따라 강도가 발현되는 특징을 갖는다. 교통개방과 공정계획 수립을 위해서는 에폭시 아스팔트 콘크리트의 강도를 정확하게 예측할 수 있어야 하며 이를 위해 에폭시 아스팔트 콘크리트의 교통개방 시점 예측 모델을 개발하였다. 현장 시공 사례에 적용 하였을 때 기존 화학반응속도론에 기초한 모델의 R2가 0.806이었으나 비선형 커브피팅을 통해 개발한 예측모델은 R2가 0.943로 보다 높은 예측 정확도를 나타내었다. 포장체의 온도데이터가 보다 많을 경우에는 예측모델과 실측값의 차이를 더 줄일 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.587-598
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• 2008

In the trackbed design using elastic multi-layer model, the stress-dependent resilient modulus is an important input parameter, which reflects substructure performance under repeated traffic loading. The resilient moduli of crushed stone and weathered granite soil were developed using nonlinear dynamic stiffness, which can be measured by in-situ and laboratory seismic tests. The prediction models of resilient modulus varying with the deviatoric or bulk stress were proposed (Park et al., 2008). To investigate the performance of the prediction models proposed herein, the elastic response of the test trackbed near PyeongTaek, Korea was evaluated using a 3-D nonlinear elastic computer program (GEOTRACK) and compared with measured elastic vertical displacement during the passages of freight and passenger trains. The material types of the test sub-ballasts are crushed stone and weathered granite soil, respectively. The calculated vertical displacements within the sub-ballasts are within the order of 1mm, and agree well with measured values with the reasonable margin. The prediction models are thus concluded to work properly in the preliminary investigation. The prediction models proposed for resilient modulus were verified by the comparison of the calculated vertical displacements with measured ones during train passages.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.25-33
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• 2015

This paper presents the d-q axis equivalent circuit model of an interior permanent magnet (IPM) which includes the iron loss resistance. The model is implemented to be able to run in real-time on the FPGA-based HIL simulator. Power electronic devices are removed from the motor control unit (MCU) and a separated controller is interfaced with the real-time simulated motor drive through a set of proper inputs and outputs. The inputs signals of the HIL simulation are the gate driver signals generated from the controller, and the outputs are the winding currents and resolver signals. This paper especially presents iron loss prediction which is introduced by means of comparing the torque calculated from d-q axis currents and the desired torque; and minimizing the torque difference. This prediction method has stable prediction algorithm to reduce torque difference at specific speed and load. Simulation results demonstrate the feasibility and effectiveness of the proposed methods.

• 자원ㆍ환경경제연구
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• 제16권4호
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• pp.803-832
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• 2007

새로운 접단에너지 사업에 대한 경제성 평가와 기존 집단에너지 시설의 최적운용을 위해서는 적어도 시간대 단위로 계측된 세부용도별 에너지 부하패턴에 관한 정보가 필수적이다. 본 연구에서는 기상자료와 냉난방 실측자료를 활용하여 열부하를 추정 예측하기 위하여 다계층모형을 선태하였다. 다계층모형은 수집한 자료의 패널자료 특성을 유연하게 모형화할 수 있는 이점이 있다. 다계층모형을 일대일의 대응관계에 있는 선형혼합효과모형으로 변환한 후 패널 FGLS(연산가능한 일반화최소자승추정법)를 적용하여 세부용도별로 열부하모형을 추정하였다. 추정된 부하모형은 온도, 습도, 시간대, 요일, 설날연휴/추석연휴 등 법정공휴일 특성, 난방면적/냉방면적이 열에너지사용량에 미치는 영향을 고려하고 있다. 지면을 고려하여 본 논문에서는 가정용 난방부하모형의 추정치와 난방부하곡선의 예측치에 제한하여 실증결과를 설명하고 있다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권4호
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• pp.241-252
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• 2013

Because of financial and safety concerns, there are needs for more accurate prediction of bridge behavior. Underestimation of the bridge load carrying capacity can have serious economic consequences, as deficient bridges must be repaired or rehabilitated. Therefore, the knowledge of the actual bridge behavior under live load may lead to a more realistic calculation of the load carrying capacity and eventually this may allow for more bridges to remain in service with or without minor repairs. The presented research is focused on the reliability evaluation of the actual load carrying capacity of existing bridges based on the field testing. Seventeen existing bridges were tested under truck load to confirm their adequacy of reliability. The actual response of existing bridge structures under live load is measured. Reliability analysis is performed on the selected representative bridges designed in accordance with AASHTO codes for bridge component (girder). Bridges are first evaluated based on the code specified values and design resistance. However, after the field testing program, it is possible to apply the experimental results into the bridge reliability evaluation procedures. Therefore, the actual response of bridge structures, including unintentional composite action, partial fixity of supports, and contribution of nonstructural members are considered in the bridge reliability evaluation. The girder distribution factors obtained from the tests are also applied in the reliability calculation. The results indicate that the reliability indices of selected bridges can be significantly increased by reducing uncertainties without sacrificing the safety of structures, by including the result of field measurement data into calculation.

• 한국화재소방학회논문지
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• 제21권1호
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• pp.51-59
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• 2007

본 연구에서는 대구에 위치한 G 지하생활공간을 대상으로 화재하중에 따른 화재성상을 분석하였다. 화재성상 예측시 화재온도나 화재지속시간을 좌우하는 인자인 화재하중 및 환기계수를 파악하기 위하여, 현장방문을 통하여 가연조건을 조사하고 실의 용도별 가연조건에 대하여 각 재료의 단위발열량을 이용하여 화재하중을 산정하였다. 또한, 산정된 실의 화재하중을 변수로 화재성상분석을 위한 6가지 모델의 축소실험을 행하고 화원의 시간에 따른 온도변화와 화원의 온도상승으로 인한 공간내부로의 열유동 분포를 중심으로 화재성상을 분석하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1370-1376
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• 2008

The structure of railroad or subway is that low fare transportation system of the large traffic volume. Like this structure is subjected to the cyclic load of moving vehicle. Consequently the result of the settlement analysis or plastic deformation prediction of railroad bed could be used as an important factor in safety of the railroad. The results of cyclic triaxial test were used in the numerical analysis of power model which Li and Selig(1994) developed. The soil samples were obtained from the construction site of railroad. Cyclic triaxial test was conducted with the variation of the magnitude of cyclic load and soil types. The large magnitude of plastic deformation in the railroad bed is caused of structure failure of the railroad.

• 한국도로학회:학술대회논문집
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• 한국도로학회 2010년 추계학술대회 논문집
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• pp.99-107
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• 2010

A permanent deformation model was developed in this study based on the shear properties of asphalt mixtures such as cohesion and friction angle. Triaxial compressive strength (TCS) and repeated load permanent deformation (RLPD) tests on the three types of asphalt mixtures are performed at various loading and temperature conditions to correlate shear properties of asphalt mixtures to rutting performance. It is observed from the tests results that the ratio of shear stress to strength accurately identifies the mixture rutting performance. It could take care of not only mixture types but also load and temperature conditions dependences. Three different versions of the permanent deformation model based on different input levels are proposed and verified using the tests data. The proposed model based on the ratio of shear stress to strength can successfully predict the permanent deformation of various asphalt mixtures all the way up to the 10% of permanent strain including all three stages of permanent deformation in a wide range of loading and temperature conditions without changing model coefficients.

• 대한기계학회논문집A
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• 제28권11호
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• pp.1741-1751
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• 2004

It is commonly requested that the steam generator tubes wall-thinned in excess of 40% should be plugged. However, the plugging criterion is known to be too conservative for some locations and types of defects and its application is limited to a single crack in spite of the fact that the occurrence of multiple through-wall cracks is more common in general. The objective of this research is to propose the optimum failure prediction models for two adjacent through-wall cracks in steam generator tubes. The conservatism of the present plugging criteria was reviewed using the existing failure prediction models for a single crack, and six new failure prediction models for multiple through-wall cracks have been introduced. Then, in order to determine the optimum ones among these new local or global failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two adjacent through-wall cracks in thin plate were carried out. Thereby, the reaction force model, plastic zone contact model and COD (Crack-Opening Displacement) base model were selected as the optimum ones for assessment of steam generator tubes with multiple through-wall cracks. The selected optimum failure prediction models, finally, were used to estimate the coalescence pressure of two adjacent through-wall cracks in steam generator tubes.

• Structural Engineering and Mechanics
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• 제52권6호
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• pp.1273-1287
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• 2014

Plates are most widely used in the hulls of floating concrete structures, bridge decks, walls of off-shore structures and liquid storage tanks. A method of analysis is presented for the determination of load-deflection response and ultimate strength of high-strength steel fiber reinforced concrete (HSSFRC) plates simply supported on all four edges and subjected to combined action of external compressive in-plane and transverse loads. The behavior of HSSFRC plate specimens subjected to combined uniaxial in-plane and transverse loads was investigated. The proposed analytical method is compared to the physical test results, and shows good agreement. To predict the constitutive behavior of HSSFRC in compression, a non-dimensional characteristic equation was proposed and found to give reasonable accuracy.