• 대한전기학회논문지:시스템및제어부문D
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• 제50권2호
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• pp.93-99
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• 2001

A new type geometric and mathematical network reduction model is introduced. Large-scale network is analyzed with analytic approach. The graph has many nodes, branches and loops. Circuit equation are obtained from these elements and connection rule. In this paper, the analytic relation between voltage source has a mutual different graphic property. Node-reduction procedure is achieved with this circuit property. Consequently voltage source value is included into the adjacent node-analyzing equation. A resultant model equations are reduced as much as voltage source number. Matrix rank is (n-1-k), where n, k is node and voltage source number. The reduction procedure is described and verified with geometric principle and circuit theory. Matrix type circuit equation can be composed with this technique. The last results shall be calculated by using computer.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.11-18
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• 2004

In this paper, an efficient model reduction scheme is presented for large scale dynamic systems. The method is founded on a modal analysis in which optimal eigenvalue is extracted from time samples of the given system response. The techniques we discuss are based on classical theory such as the Karhunen-Loeve expansion. Only recently has it been applied to structural dynamics problems. It consists in obtaining a set of orthogonal eigenfunctions where the dynamics is to be projected. Practically, one constructs a spatial autocorrelation tensor and then performs its spectral decomposition. The resulting eigenfunctions will provide the required proper orthogonal modes(POMs) or empirical eigenmodes and the correspondent empirical eigenvalues (or proper orthogonal values, POVs) represent the mean energy contained in that projection. The purpose of this paper is to compare the reduced order model using Karhunen-Loeve expansion with the full model analysis. A cantilever beam and a simply supported plate subjected to sinusoidal force demonstrated the validity and efficiency of the reduced order technique by K-L method.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.337-344
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• 2001

Some as-built drawings in national roadway bridges in Korea were examined. There are many bridge piers, whose aspect ratios are in the vicinity of 2.5. These columns are expected to do shear-flexure behaviour and have large scale effect between full and reduced scale model. In the study, full and 1/2 scale model tests on the shear-flexure behaviour columns were carried out. The seismic performance of existing bridge piers without seismic details were examined by Quasi Static Test

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.251-258
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• 2008

The use of reinforced earth walls in permanent structures is getting it's popularity. Despite a number of advantages of reinforced earth walls over conventional concrete retaining walls, there exit concerns over long-term residual deformation when subjected to repeated and/or cyclic loads, during their service period. In this investigation, the effect of preloading in reducing long term residiual deformation of back-to-back reinforced soil wall under sustained and/or repeated loading enviormentment using a series of reduced-scale model tests. It is found that the preloading technique can be an effective means of controlling residual deformations of reinforced soils under varisous loading conditions.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.121-130
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• 2006

Despite a number of advantages of reinforced earth walls over conventional concrete retaining walls, there exit concerns over long-term residual deformation when used as part of permanent structures. In view of these concerns, time-dependant deformation characteristics of geosynthetic reinforced modular block walls under sustained loads were investigated using reduced-scale model tests. The results indicated that a sustained load can yield appreciable magnitude of residual deformation, and that the magnitude of residual deformation depends on the loading characteristic as well as reinforcement stiffness.

• 설비공학논문집
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• 제16권2호
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• pp.135-141
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• 2004

The present paper concerns a smoke movement in a tunnel fire with a vertical shaft. The model tunnel measured 13.4m long, 0.4m wide and 0.4m high. The cross section is 1： 20 of a full scale tunnel. Ethanol was used as a fuel. The fire size in model tests varied from 1.35 kW to 13.37 kW, which corresponds to full scale fires of 2.41 to 23.91 MW. Smoke front velocity and temperatrue were decreased due to the vertical shaft install. Temperature was reduced maximum about 2$0^{\circ}C$ at ceiling and about 23$^{\circ}C$ at vertical position. CO concentration was reduced as the vent width widened. When vent width was more than 15 cm, CO concentration was not reached 100 ppm. Descent degree of the smoke layer was confirmed through the visualization.

• 대한전기학회논문지
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• 제35권8호
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• pp.333-340
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• 1986

This paper presents an approach for determining the discrete reduced-order models for largescale system by using matrix sign function. We define projection operators based on the matrix sign function and develop the algorithm for model-reduction by using them. Simulation studies show that the proposed altgorithm is very useful.

• 한국구조물진단유지관리공학회 논문집
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• 제8권4호
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• pp.257-264
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• 2004

공동주택 수익모델의 가치를 형성하는 요소 중 영향도가 큰 물리적 요소는 주택의 평형변화로서 이를 중심으로 리모델링의 대안을 제안한다. 이에 따라 본 연구에서는 공동주택의 가치형성요인과 공간구성기법을 이용한 큰 평형의 세대를 작은 평형의 세대로 분할하는 모델과 작은 평형의 세대를 통합하여 큰 평형의 세대로 변환하는 모델의 수익모델을 설정하여 경제성은 '보통'이상 '양호'한 것으로 나타났으며, 경제성 평가값은 할인율이 증가함에 따라 감소하며 리모델링의 경제성이 우수해지는 것으로 나타남을 알 수 있다.

• 한국기계연구소 소보
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• 통권10호
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• pp.35-48
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• 1983

When the hydrodynamic coefficients of the ship maneuvering equation are estimated by captive model test, it is difficult to take account of the scale effect between model and full scale ship. This scale effect problem can be overcome by processing the sea trial data with system identification. Extended Kalman filter is used as a system identification technique for the modification of the simulation equation as well as the estimation of hydrodynamic coefficients. The phenomena of simultaneous drifting of linear coefficients occur. It is confirmed that two coefficients in each pair-($Y_v$', $Y_r$' -m' u'), ($N_v$', $N_r$' )-are simultaneously drifting and all 4 coefficients are simultaneously drifting together. Particularly simultaneous drifting of 2 coefficients in each pair is more significant. It is also shown that the simultaneous drifting of 4 coefficients can be reduced by choosing the input data which have the random v'/r' curve and 4 coefficients are estimated within 2-4% error, which may be noise level. So, it is recommended to operate the rudder randomly in sea trial or model test for the application of system identification technique.

• 한국지반공학회논문집
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• 제31권1호
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• pp.15-24
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• 2015

본 논문에서는 지반 시추시 공벽붕괴 방지를 위해 적용되는 시추 안정액(drilling fluid)의 다양한 배합설계에 따른 공벽붕괴 방지 효과에 대한 실험적 연구 결과를 다루었다. 이를 위해 먼저 벤토나이트 계열 안정액의 공벽 붕괴 방지 메카니즘을 검토하였으며 아울러 벤토나이트계 안정액의 배합(conditioning)에 따른 안정액의 성능지표 변화에 대한 실험결과를 간략히 기술하였다. 또한 지반시추(굴착) 및 안정액 투입을 간략히 모사하는 토조 장치를 구축하여 세립분이 20% 포함된 화강풍화토 및 모래지반을 대상으로 다양한 배합으로 조성된 벤토나이트계 안정액에 대한 실험을 수행하고 안정액 투입량, 수평 침투범위, 굴착가능 깊이 등을 측정하여 공벽붕괴 방지 효과를 고찰하였다. 그 결과 벤토나이트에 폴리머를 추가할 경우 안정액 투입량 및 수평 침투범위가 굴착가능 깊이가 증가하는 것으로 나타났으며 폴리머의 공벽유지 기능 향상 정도는 모래층보다 화강풍화토 지반에서 보다 뚜렷하게 발휘되는 것으로 검토되었다. 본 논문에서는 도출된 연구결과가 실무적 차원에서 지니는 의미에 대한 내용을 기술하였다.