• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.16-18
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• 2008

연약지반에 시공된 콘크리트전주가 풍하중에 의해 받는 웅력-변형 특성을 파악하기 위해 전주 매설깊이, 버팀대의 위치 및 수량 등을 변수로 하중 파괴 시험을 실시한 결과, 전주가 깊이 묻혀질수록 재하하중에 따른 수평변위는 감소하였고 전주의 버팀대는 2개일 경우 가장 안정되는 것으로 조사되었다.

• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.30-36
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• 2003

궤도(track)는 열차가 안전하고 승차감(乘車感)이 좋게 운행되도록 충분한 강도를 가지고 더욱이 양호한 상태로 정비되어 있어야 한다. 일반적으로, 토목구조물(structure)은 하중을 받으면 변위(變位)ㆍ변형하고, 하중이 없게 되면 원래대로 되돌아간다. 즉, 각 부재는 탄성 한계 내로 응력(應力)이 들어가도록 설계된다. 그러나, 궤도는 열차의 하중과 진동을 궤도 자신의 변위 축적으로 흡수하고 있다. 결국, 처음부터 틀림이 진행되어 가는 것을 전제로 한 유일한 구조물이다. 일반적으로는 스프링 하 중량과 축중(軸重)이 큰 차량이 빠르고 대량으로 주행하게 되면 궤도 틀림이 발생하여 진행한다. 궤도 틀림 파형의 성장은 궤도 틀림이라고 하는 공간적인 파형의 시간적인 추이라고 하는 2차원적인 취급이 필요하다. (중략)

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.1-10
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• 2022

In this study, to evaluate the possibility of using a steel spring as a displacement-dependent damping device, tensile loading and cyclic loading tests were performed. The main experimental variables were the type of steel (SAE9254 and SS275), the spring constant (700 N/mm, 1,000 N/mm, and 1,400 N/mm), and the presence or absence of heat treatment for SAE9254. As a result of the tensile test, the ratios of the measured spring constant to the design spring constant of the steel springs made with SAE9254 ranged from 1.08 to 1.13, while the ratios of the design spring constant and the measured spring constant of the steel springs made with SS275 ranged from 0.86 to 0.97. After yielding, the slope values of the load-displacement curve of the SAE9254 with/without heat treatment were about 240~251 N/mm and 92 N/mm, respectively, but the slope values of the load-displacement response of SS275 were almost zero. According to the uniaxial cyclic loading test results, all specimens were satisfied with three conditions for a displacement-dependent damping device in KDS 41 17 00 (2019): the maximum force and minimum force at zero displacement, the maximum force and minimum force at the maximum displacement, and the energy dissipation capacity. In addition, the equivalent damping ratios of steel springs made with SAE9254(non-heat treatment) and SS275 were approximately 2.8 times and 1.9 times greater, respectively, than that of steel springs made with SAE9254.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.859-869
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• 2009

The sharp indenters such as Berkovich and conical indenters have a geometrical self-similarity in theory, but different materials have the same load-depth curve in case of single indentation. In this study, we analyze the load-depth curves of conical indenter with angles of indenter via finite element method. From FE analyses of dual-conical indentation test, we investigate the relationships between indentation parameters and load-deflection curves. With numerical regressions of obtained data, we finally propose indentation formulae for material properties evaluation. The proposed approach provides stress-strain curve and the values of elastic modulus, yield strength and strain-hardening exponent with an average error of less than 2%. It is also discussed that the method is valid for any elastically deforming indenters made of tungsten carbide and diamond for instance. The proposed indentation approach provides a substantial enhancement in accuracy compared with the prior methods.

• Tunnel and Underground Space
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• v.21 no.3
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• pp.192-204
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• 2011

In this study, 3-D analyses were conducted while taking every construction stage into account. Then 2-D analyses were conducted which yield the same results with the 3-D results. The crown settlement normalized by the ultimate value was compared during the process to overcome the discrepancy caused by different dimensions. When a bench or a core is left uncut to give extra support to the face and eventually the whole excavation boundary, this extra supporting effect also has to be included in the analysis. In this study, this effect is also implemented in terms of the load distribution factor. When the length of the bench is very short compared to the diameter of the tunnel in such cases as in short bench cut or in mini-bench cut, the supporting effect of the face does not disappear even after the bench is completely excavated and supported since the face is still too close to the point of interest. The 4th load distribution factor was defined to stand for the advance of the face after the completion of the excavation cycle. The 4th load distribution factor turned out to be very useful in determining the load distribution factors when a tunnel is excavated by bench cut with various bench lengths under different initial conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.503-512
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• 1990

In this study, a penalty method effective for the case that has no snap-back phenomenon, is proposed and an adaptive method which choose the penalty method or Riks' type method, is suggested for the case of snap-back problem. And for the case that loads are applied to one or more points of a structure, the Riks' method is applied in general, but under certain condition choice of new incremental load parameter is suggested to accelerate the convergence rate. Finally, for the case that displacements of a structure are controlled at one or more points Riks' type method is proposed. In this case, the proposed method is applied in general but under certain condition it is recommended to choose other incremental displacement parameter to eliminate probable divergence. Five examples are analysed and compared with the result of published literature.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.2
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• pp.40-48
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• 2016

To observe the rail-slab interaction in continuous welded railway(CWR) bridge when earthquake occurs, additional axial rail stresses and relative longitudinal displacements between rail and bridge deck were calculated with input of various load combinations and 3 different types of seismic loads to an analytical model. As results of analysis, it can be found that standard response spectrum proposed by Korea Rail(KR) network authority for earthquake design showed less additional axial rail stresses than allowable levels, but greater relative longitudinal displacement between rail and bridge deck, which means that adjustment of relative longitudinal displacement within a standard level is much more difficult than axial train stress. Additionally, if a large-scaled earthquake as occurred at Kobe, Japan comes up, then both of additional axial rail stress and relative displacement in rail-bridge deck may exceed allowable levels, which indicates to make proper design guides against sudden earthquake occurrence.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.198-199
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• 2011

플로팅 함체는 육상과 달리 지진하중의 영향을 받지 않으며 파랑하중의 영향을 크게 받는다. 파랑하중에 대한 안전성을 확보하기 위하여 범용구조해석 프로그램을 이용하여 해석하였다. 상부구조물의 영향을 확인하기 위하여 함체의 밀도를 변화시켜 상부하중에 대한 함체의 변위 응답을 확인을 한 결과, 밀도에 따른 함체 거동의 변화는 미미하였다. 해석을 통해 얻은 각 주기별 변위를 하중에 적용한 상부구조물의 모멘트 증가비는 파랑하중의 주기가 단주기에서 장주기로 갈수록 감소하는 양상을 보였으며, 축력은 파랑주기의 영향을 적게 받는 것으로 나타났다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.251-259
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• 2001

본 논문은 직접 변위 설계법의 기본개념을 이용하여 비대칭 평면을 갖는 벽 식구조의 변위에 근거한 내진설계방법을 제안한다. 제안된 설계방법은 구조시스템의 각 벽체의 강도비와 강성비 및 목적 설계 변위를 결정하고, 직접 변위 설계법에 따라 설계하중은 구하는 과정으로 이루어진다. 탄성 영역에서는 강성 편심을, 비탄성 영역에서는 강도 편심을 주요한 설계변수로 사용하였다 성능에 기초한 내진설계의 개념에 따라 비대칭 평면을 갖는 구조물이 요구되는 성능 수준을 효과적으로 만족할 수 있도록 본 논문은 시스템의 비틀림 미케니즘과 각 벽체의 변형능력을 고려하였다. 제안된 설계방법을 이용하여 중진과 강진 지역에 대해 예제 구조물의 설계하중을 구하고, 최적의 설계방법을 제안하였다.

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.163-174
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• 2007

A New pre-loading system, through which a large pre-load could be charged was developed and applied to the braced wall in order to stabilize the adjacent tunnel. A pre-load larger than the designated axial force of bracing was imposed to prevent the horizontal displacement of the braced wall during the ground excavation. For this purpose, real scale model tests (1/10) were conducted, without and with pre-load on braced wall. And numerical analyses were performed for both the cases without and with pre-load, which were half (50%) and full (100%) respectively, and larger scale of the design axial farce of bracing. FEM program called PLAXIS was used for numerical analysis. As a result, it was found that the stability of the existing tunnel adjacent to the braced wall could be greatly enhanced when the horizontal displacement of braced wall was reduced by applying a pre-load, which was larger than the designated axial force of bracing.