• Proceedings of the Korea Information Processing Society Conference
• /
• 2006.11a
• /
• pp.15-18
• /
• 2006

강화 학습은 시행착오를 통해 동적 환경과 상호작용하면서 학습을 수행하는 학습 방법으로 본 논문에서 테스트 환경으로 사용하는 Keepaway와 같은 동적인 환경에서 주로 사용하는 학습 방법이다. 본 논문에서는 학습을 통한 에이전트가 다른 정책을 사용하는 에이전트보다 성능이 더 높다는 것을 보이고자 한다. 학습 초기에는 다양한 전략을 평가하기 위해 최적이 아닌 행동을 선택하지만 시간이 지남에 따라 최적의 행동 선택에 수렴해 가는 것을 보이기 위한 실험을 수행한다. 이 실험을 통해 고정된 행동 양식을 가지는 정책보다 강화 학습을 이용한 에이전트들의 성능이 더 효과적인 것을 알 수 있었다.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.8
• /
• pp.126-134
• /
• 1998

본 연구에서는 회전운동을 제어하기 위한 새로운 작동기로서 전기장에 대하여 매우 빠른 응답특성을 갖고 있는 두 쌍의 실린더형 ER(electro-rheological) 클러치/브레이크 작동기를 제안하였다. 자체조성 된 ER유체의 빙햄특성 모델을 실험적으로 도출하였으며, 이와 연계한 작동기 모델을 구성하여 전기장에 따른 전달 및 제동 토크를 해석한 후 알맞은 크기의 클러치/브레이크 작동기를 제작하였다. 제작된 작동기의 동적특성(시상수 등)을 작동기 모델에 고려하기 위하여 계단입력 전기장에 따른 과도응답 실험을 클러치와 브레이크 모드에서 각각 수행하였다. 제안된 작동기의 응용성을 보이기 위하여 두쌍의 작동기로 구동되는 실험실 차원의 소형 와권식 세탁기 시스템을 구성한 후 동적지배방정식을 유도하다. 각 작동기와 연계된 PID제어기를 설계하여 세탁과 탈수시의 회전운동을 제어하였으며, 부하질량의 변화에 대한 작동기 시스템의 제어 효율성과 장시간 운전을 통한 제어 내구성 실험을 수행하였다.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.9 no.2 s.42
• /
• pp.7-15
• /
• 2005

Numerical analysis model is proposed to predict the dynamic behavior of a single-degree-of-freedom structure that is equipped with hybrid base isolation system. Hybrid base isolation system is composed of friction pendulum systems (FPS) and a magnetorheological (MR) damper. A neuro-fuzzy model is used to represent dynamic behavior of the MR damper. Fuzzy model of the MR damper is trained by ANFIS (Adaptive Neuro-Fuzzy Inference System) using various displacement, velocity, and voltage combinations that are obtained from a series of performance tests. Modelling of the FPS is carried out with a nonlinear analytical equation that is derived in this study and neuro-fuzzy training. Fuzzy logic controller is employed to control the command voltage that is sent to MR damper. The dynamic responses of experimental structure subjected to various earthquake excitations are compared with numerically simulated results using neuro-fuzzy modeling method. Numerical simulation using neuro-fuzzy models of the MR damper and FPS predict response of the hybrid base isolation system very well.

• Journal of the Korean Society for Railway
• /
• v.16 no.4
• /
• pp.305-310
• /
• 2013

In general, it is difficult to measure dynamic responses of a bridge with stepwise increasing speed of a train during commercial service on a high speed railroad. However, before opening the 2nd stage of the Gyeongbu high speed railroad, there was an opportunity for field tests and measurements of the bridge with stepwise increasing speed(from 170km/ h to 315km/h). The measured responses were compared with the results of a developed bridge/train interaction analysis. Although good agreement was found throughout almost the entire range of speeds, relatively large differences were found in the vicinity of the critical speed at which resonance behavior of the bridge occurs. To investigate the cause of this, reanalyses are performed with re-estimated damping ratios from field tests.

• Explosives and Blasting
• /
• v.37 no.1
• /
• pp.14-23
• /
• 2019

It has been an always issue for the blasting or the impact analysis to consider the strength characteristics of the rock materials associate with loading rate dependency. Due to the nature of transient loading, the dynamic rock test requires a careful technique to achieve the stress equilibrium state of the specimen. In this study, to investigate the relationship between the rock dynamic strength and the stress equilibrium state, a series of dynamic uniaxial compression tests for Pocheon granite were performed. As a result, the unbalanced stress state on the specimen can lead to the premature failure on the specimen and the less estimation of dynamic strength characteristic as well as the overestimation of strain rate. Consequently, a careful consideration of rock fracture process to achieve the dynamic force balance on the specimen should be required to make an reasonable evaluation of rock dynamic strength.

• Journal of the Korean Geotechnical Society
• /
• v.17 no.6
• /
• pp.173-180
• /
• 2001

This research is aimed at investigating the dynamic response of cut-and-cover tunnel to seismic waves. We carried out shaking table test which is used a 1/40-scale(the width of prototype tunnel is about 14.2m, the height is about 8.5m) model for this research, and we analyzed the effect of depth of tunnel and slope of the ground in relation to the dynamic responses of tunnel. As a result of the test, the stress and acceleration along the tunnel decreased accordingly to the depth of increment, and this phenomenon is caused by the increase of the confining effect of ground. Also, the dynamic responses of tunnel showed a tendency to rise according as ground declined gently. In comparison the result of shaking table test with that of structural analysis on ordinary condition, we conclude that seismic waves do not affect cut-and-cover tunnel when the depth of tunnel is over the diameter of tunnel.

• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.76-76
• /
• 2011

현재까지 시공된 사장교 중, 주경간이 가장 긴 교량은 중국의 수통대교(1088m)이다. 이에 버금가는 사장교로 홍콩의 스톤커터교(1018m) 역시 주경간장이 1000m가 넘는다. 바야흐로 사장교 역시 주경간 1000m의 시대가 열린 것이다. 우리나라 역시 세계적 흐름에 맞추어 주경간 800m의 인천대교(세계 5위)를 시공한바 있다. 이와 같이 교량의 초장대화는, 교량 건설 분야에서 기술경쟁력의 지표가 될 뿐만 아니라 세계 건설 시장의 큰 흐름이라고 할 수 있다. 이에 본 연구는 세계적 추세에 발맞추어, 국내 각계의 건설 전문가들이 모여 만든 초장대 교량 사업단의 기술 혁신 사업의 일환으로 이루어졌다. 교량이 장대화 되면서 바람의 의한 영향이 중요해진다는 것은 주지의 사실이다. 특히 사장교와 현수교 같은 특수 교량의 경우, 정적 및 동적 내풍 성능이 반드시 고려되어야만 한다. 본 연구에서는 주경간 1200m의 사장교를 가정하고, 이 사장교의 내풍 단면을 개발, 그 단면에 대한 정적 및 동적 내풍 성능을 평가하고자 하였다. 정적 내풍 성능으로는 단면의 형상에 따른 풍하중을 파악하고자 했으며, 동적 내풍 성능으로는 풍속에 따른 교량의 연직방향 변위 및 플러터 속도를 파악하고자 하였다. 이 실험은 추후에 3차원 전교모형실험의 기본 데이터로 활용하였다. 본 실험을 통해 개발된 단면의 등류 및 난류 상태에서의 영각별 정적 공기력계수를 계산해내었고, 설계풍속이 54.7m/s일때 한계풍속 65.64m/s(거마대교 기준)하에서의 중앙 경간의 풍속별 평균 변위를 측정하였으며, 이를 토대로 이 교량의 영각별 플러터 속도를 계산해 내었다.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.7
• /
• pp.51-58
• /
• 2018

In this study a series of centrifuge tests were carried out in dry sand to analyze the comparison of lateral pile behavior for static loading and dynamic loading condition. In case of static loading condition, the lateral displacement was applied up to 50% of pile diameter by deflection control method. And the input sine wave of 0.1 g~0.4 g amplitude and 1 Hz frequency was applied at the base of the soil box using shaking table for dynamic loading condition. From comparison of experimental static p-y curve obtained from static loading tests with API p-y curves, API p-y curves can predict well within 20% error the ultimate subgrade reaction force of static loading condition. The ultimate subgrade reaction force of experimental dynamic p-y curve is 5 times larger than that of API p-y curves and experimental static p-y curves. Therefore, pseudo-static analysis applied to existing p-y curve for seismic design could greatly underestimate the soil resistance at non-linear domain and cause overly conservative design.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.37 no.4
• /
• pp.647-657
• /
• 2017

The main purpose of this study is to investigate the static & dynamic behavior of a precast bracket under precast road deck slab of double deck tunnel. In order to improve the construction speed, the field prefabricated bracket to connect the intermediate slab to the precast shield tunnel lining structure has been developed in the 'SPC (Steel Precast Concrete) bracket'. The experiments were performed for the full scale model in order to evaluate the performance of the 'SPC bracket', the structural stability was verified through the FEM analysis. The result of static loading test, no deformations or cracks of the bracket undergo the ultimate load was investigated. In addition, no pulling or deformation of the chemical anchor for fixing the bracket was measured. As a result of dynamic loading test, it was investigated that there is no problem in the chemical anchor for fixing the bracket. FEM analysis showed similar behavior to static load test and it was determined that there is no problem in serviceability and structural safety.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.1A
• /
• pp.45-52
• /
• 2010

This study pointed on the dynamic impact of AGT (Automated Guide-way Transit) bridge, due to concrete rail prominence. An experiment was done with 30 m P.S.C. bridge in AGT test line in Kyungsan. An artificial prominence with 10 mm hight, was installed at the mid span of concrete rail. And computer simulation was executed for the artificial prominence. As an experiment result, in the case of with prominence, bridge acceleration responses are increased 50% at the speed range of 20 km/h-60 km/h, and bridge displacement responses increased slightly. With these results, the prominence of concrete rail can be induce excess impact and vibration. And the computer program simulated much the same as experiments. So this program can be used for AGT bridge design and formulate the standard of concrete rail management.