• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.201-212
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• 2007

This study presents experimental results of Steel-PSC mixed structural system having front-rear plate connection between Steel and Prestressed Concrete. Two kinds of Steel-PSC mixed structural system of 5.4m length were tested to evaluate flexural behaviors under four point loading, and 4 kinds of specimens with and without prestressing force at R & L type connection were tested to observe the shear behavior. Based on the test results of load-deflection curves and failure modes of specimens, it is found that the proposed L shape connection with front-rear plate connection between Steel and Prestressed Concrete has higher strength and stiffness. From the study, Steel-PSC mixed structural system with L shaped connection has a better structural performance in connection part.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.343-351
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• 2010

Bending and axial compressive stresses are distributed across the whole upper flange of a box girder bridge which has the span-to-depth ratio (B/L) of below 0.5, according to Korea Bridge Design Specifications (Minister of Land, Transport and Maritime Affairs, 2005). Shear lag phenomenon, however, can take place in the construction phase of cable-stayed bridge, in which stresses combining bending moment due to dead weight and cable vertical compression are induced. This study aims to analyze the effective width of flange over which composite stresses are given, which should be calculated during the construction phase of stiffening girder of single plane cable-stayed box girder bridge. The study results indicate that the full width of stiffening girder can be regarded as the effective flange width when the span-to-depth ratio for the deck is below 0.38. In other words, the area, where shear lag is taken into consideration, is larger than the width of box girder in single plane cable-stayed box girder bridges. Therefore, the current practice of considering the full width as the effective flange width regardless of changes of the span-to-depth ratio during the construction stage can produce an unsafe bridge. If the effective flange width is determined according to the single span structural system in the early stage of construction when the span-to depth ratio for the deck is high and composite stresses of every part expect each end of the bridge are calculated, it can result in a safe structural design. Since the span-to-depth ratio gradually decreases, however, it is appropriate to determine the effective width of flange on the basis of the full width and the cantilever structural system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.11
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• pp.55-62
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• 2001

Field penetration and scattering characteristics of two dimensional open cylindrical cavity is studied. Exact analysis for this sort of structure is not achieved even if there are unusual phenomena of field penetration and scattering with cavity and aperture size. In this paper, we calculate a wide range of open cavity characteristics by using of FMM method, which is extended method of MOM. We find external mode of open cylindrical cavity corresponding to internal mode of closed cavity. The characteristics of resonance and scattering of this region is different compare with non resonant area. The result of study will apply to the EM wave shielding and RCS control.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.742-747
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• 2004

최근 들어 지구온난화에 따른 이상기후 및 집중호우 빈발 그리고 급격한 도시화와 산업화는 예측하기 어려운 수문현상의 변화를 유발시키고 있다. 이에 따른 유출양상의 변화는 수문분석에 의한 기존의 설계기준에도 변화를 요구하고 있다. 즉, 설계빈도의 무조건적인 상향조정에 따른 확정론적인 방법에 의존하기보다는 수문량의 변화를 통계학적으로 반영한 수 있도록 불확실성 분석이 필요하게 되었다. 따라서 설계홍수량에 따른 범람면적별 홍수피해액을 산정할 때 설계홍수량에 대한 불확실성 분석을 수행함으로써 안전율을 고려 할 범람과 홍수피해액을 추정할 수 있는 것이다. 본 연구에서는 Bayesian에 의해 불확실성을 고려한 빈도별 설계홍수량을 산정하였으며, HEC-GeoRAS와 HEC-RAS 및 ArcView GIS 3.2a를 이용해 홍수범람면적을 수치지형도에 도시하고, 범람면적별 홍수피해액을 산정하였다. 또한, 불확실성을 고려하지 않은 경우에 대해서는 L-모멘트법을 이용해 설계홍수량을 구하고 홍수범람면적파 홍수피해액을 산정하였다. 불확실성의 고려 여부에 따른 설계홍수량과 예상 홍수피해액을 비교${\cdot}$분석한 결과 불확실성을 고려한 경우가 불확실성을 고려하지 않은 경우에 비해 설계홍수량은 $7\~33\%$, 예상 홍수피해액은 $1\~4\%$정도 차이를 보였다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.4
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• pp.250-260
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• 1992

Two methods for computing extreme sea levels, which are the extreme probability method and the joint probability method, are examined at five different ports (Incheon, Cheju, Yeosu, Pusan, Mukho). The extreme probability mothod estimates the extreme sea levels from three different probability papers of Gumbel, Weibull and generalized extreme value(GEV) using the least square method, conventional moment method and probability weighted moment method. respectively. The results showed that the extreme sea levels estimated by the Gumbel paper or the least square method appeared higher than those calculated by other papers or methods. The extreme values estimated by the extreme probability method are approximately 5-10 cm lower than the values by the joint probability method.

• Korean Journal of Optics and Photonics
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• v.2 no.4
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• pp.203-208
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• 1991

We investigated the nonradiative energy transfer process from Rhodamine 6G to Malachite Green in ethylen glycol solvent using time correlated single photon counting system equipped with a modelocked Ar ' laser. The reduced concentration and critical transfer distance for various acceptor concentration were obtained by using a full-fitting analysis of the fluorescence decay curves. We found that Huber model is more suitable than Forster model and the influence of energy migration through the dipole-dipole interaction becomes more significant for the low acceptor concentrations relative to the donor concentration($5\times 10^4$mol/l).

• Computational Structural Engineering
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• v.8 no.3
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• pp.103-111
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• 1995

Evaluating nonlinear response of a MDOF system under dynamic stochastic loads such as seismic excitation usually requires excessive computational efforts. To alleviate this computational difficulty, an approximation is developed in which the MDOF inelastic system is replaced by a simple nonlinear equivalent system(ENS).Me ENS retains the most important properties of the original system such as dynamic characteristics of the first two modes and the global yielding behavior of the MDOF system. The system response is described by the maximum global(building) and local(interstory) drifts. The equivalency is achieved by two response scaling factors, a global response scaling factor R/sub G/, and a local response scaling factor R/sub L/, applied to the responses of the ENS to match those of the original MDOF system. These response scaling factors are obtained as functions of ductility and mass participation factors of the first two modes of structures by extensive regression analyses based on results of responses of the MDOF system and the ENS to actual ground accelerations recorded in past earthquakes. To develop the ENS with two response scaling factors, Special Moment Resisting Steel Frames are considered. Then, these response scaling factors are applied to the response of ENS to obtain the nonlinear response of MDOF system.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.235-244
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• 2016

This study was conducted to verify seismic performance of special moment frame's joints at roof-level with high-strength concrete and SD600 bars. K-RC-H was designed according to the seismic code and K-HPFRC-H had 150% of the original hoop spacing and 1.0% steel fiber volume fraction compared with K-RC-H. Both specimens had remarkable seismic performance without noticeable decrease in moment, but with very good energy dissipation before rebar failure. The U-bars in the joint sufficiently constrained rebar's action that pushed the cover upward. SD600 bars with $1.25l_{dt}$ had minimum slip in the joint. It was considered that the steel fiber contributed to improvement of the bending moment and joint shear distortion, and the result showed that it would be possible to increase the hoop spacing to 150% of the regular spacing.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.23-36
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• 2008

This study describes model tests on instrumented rectangular-shaped passive row piles embedded in horizontal sand-ground undergoing lateral soil movement. We tried to find the property of row piles dependent on the shape of pile, including the position of the pile in row, pile spacing, and soil movement. The results of test are as follows. The lateral earth pressure diagram variously appeared to be triangle, trapezoid and rectangular by shape and position of pile. The outer pile has a larger bending moment than the inner pile in the case of B-type, the inner piles has larger one than outer pile in case of H-type. $R_f$ (the ratio of resistance to lateral soil movement) was found to increase with increasing pile spacing irrespective of pile-shape. Y/L (location of action of lateral resistance force) for $d_s$ (displacement of soil) and $S_h$ (spacing of pile) appeared to be nearly regular position, and H-type is higher than B-type.

• Journal of Bio-Environment Control
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• v.17 no.3
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• pp.197-203
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• 2008

This study was performed to check the structural safety of modified 1-2W Greenhouses to be utilized fur growing Paprika. This type of greenhouse was derived from being remodeled by enhancing the column height of conventional 1-2W type greenhouses. According to the results of structural analysis performed by SAP-2000, there was not significant change in critical snow depth in spite of increasing the column height of 1.2 m by welding. But the critical wind velocities were shown to be $26.0\sim4l.0m/s$, which were $3\sim18%$ lower wind velocities compared with those critical velocities estimated for typical type of 1-2W greenhouse. Under the wind loads, those maximum section forces such as shear force, axial force, and bending moment, together with the deformed frame shape of strained greenhouse, were almost similar in both typical type and modified type. Maximum bending moment of column was found at eave's height of column on windward side. Under the snow loads, those maximum section forces such as shear farce, axial force, and bending moment, together with the deformed frame shape of strained greenhouse, were almost similar in both typical type and modified type. Maximum section forces except axial force was found at eave's height of column. Maximum axial force was found at inner column. Soil bearing capacity together with the total foundation resistance against wind upheaval was found to be consistently safe enough to resist to both wind load and snow load.