• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2006년도 학술발표회 논문집
• /
• pp.645-650
• /
• 2006

This paper presents the results of a study to verify the sufficient control performance of semiactive tuned mass damper and to identify suitable control methods for semiactive tuned mass damper in structural vibration control. In this study, four control algorithms are considered: on-off displacement based groundhook, on-off velocity based groundhook, clipped optimal and maximum energy dissipation algorithm. For semiactive tuned mass damper, MR damper is considered as a controllable damping device and the command voltage is calculated by the control algorithms. Each of the control theory is applied to the three story shear building excited by three earthquakes. The performance of each algorithm is compared with that of conventional tuned mass damper system using evaluation criteria. The simulation results indicate that semiactive tuned mass damper has control efficiency. Among the control algorithms, on-off displacement based control theory shows the best efficacy and robustness.

• 한국기계기술학회지
• /
• 제13권1호
• /
• pp.41-47
• /
• 2011

In this study, the structural analysis of cooling fan is combined with 3-D flow analysis by using CFD on fluid domain. The smoothly cooling flow with optimum design of cooling parts is essential at automotive combustion engine. The fan shape is modeled with three kinds of shape by varying the radius of the fan blade. By the results of analysis, the flow at Model I is more uniform than Model II or III. And the displacement at Model I is less than Model II or III. As the flow resistance of cooling fan at Model I decreases more than Model II or III, the efficiency becomes better.

• 한국안전학회지
• /
• 제37권6호
• /
• pp.60-70
• /
• 2022

This paper proposes an optimal design method of a seismic reinforcement system for the seismic performance of adjacent asymmetric-stiffness structures with viscous dampers. The first method considers plan asymmetry for efficient seismic reinforcement, and evaluates the seismic performance of optimal design applied to two cases of modeling: adjacent stiffness-asymmetric structures and adjacent stiffness-symmetric structures. The second method considers the response of asymmetric structures to derive the optimal objective function, and evaluates seismic efficiency of the objective function applied to two cases of responses: horizontal displacement and torsion. Numerical analyses are conducted on 7- and 10-story structures with a uni-asymmetric-stiffness plan using six cases of historic earthquakes, normalized to 0.4g. The results indicate that the seismic performance is excellent as modeled by adjacent asymmetric-stiffness structures and how much horizontal displacement is applied as the objective function.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.472-475
• /
• 2003

Electric Power Steering (EPS) mechanism has become widely equipped in passenger vehicle due to the environmental consciousness and higher fuel efficiency. This paper describes the development of co-simulation technique and simulation integration technique of EPS control system with dynamic vehicle model. A full vehicle model interacted with EPS control algorithm is concurrently simulated on a single bump road condition. Dynamic responses of vehicle chassis and steering system resulting from road surface impact are evaluated and compared with proving ground experimental data. The comparisons will show reasonable agreement on tie-rod load. rack displacement, handle-wheel torque and tire center acceleration. This developed simulation capability can be used for EPS performance evaluation and calibration as well as for vehicle handling performance integration and synthesis.

• Journal of Advanced Marine Engineering and Technology
• /
• 제18권2호
• /
• pp.104-112
• /
• 1994

The scavenging efficiency has a great influence on the performance of a diesel engine, especially slow two-stroke diesel engines which are usually used as a marine propulsion power plant. And this is greatly affected by the conditions in the cylinder, scavenging manifold and exhaust manifold during the gas exchange process. There are many factors to affect on the scavenging efficiency and these factors interact each other very complicatedly. Therefore the simulation program of the gas exchange process is very useful to improve and predict the scavenging efficiency, due to the high costs associated with redesign and testing. In this paper, a three-zone scavenging model for two-stroke uniflow engines was developed to link a control-volume-type engine simulation program for performance prediction of long-stroke marine engines. In this model it was attempted to simulate the three different regions perceived to exist inside the cylinder during scavenging, namely the air, mixing and combystion products regions, by modeling each region as a seperate control volume. Finally the scavenging efficiency was compared with three type of scavenging modes, that is, pure displacement, partial mixing and prefect mixing.

• 한국화재소방학회논문지
• /
• 제30권1호
• /
• pp.104-110
• /
• 2016

본 연구는 2012년도에 제정된 원심펌프 기준에 바탕을 둔 소방자동차용 소방펌프의 성능 인정 기준에 각종 초고층 건물의 화재 및 대형화재에 대비하기 위한 고압 및 대용량의 방수 능력을 가진 용적형 펌프의 인정기준 추가에 관한 내용이다. 용적형 펌프의 실험을 바탕으로 V-1, 2, 3급의 3가지에 대한 성능에 대하여 인정기준을 제정하였으며 펌프의 효율은 원심펌프형과 동일한 65% 이상의 성능을 요구하는 인정기준이 포함 되었다. 방수압력은 1.5 MPa~2.5MPa 사이의 값을 유량은 최소 $0.31m^3/min$에서 최대 $3.0m^3/min$의 방수량의 성능을 요구하는 것으로 제정되었다. 또한, 구조적으로 체절압력을 조절해야하는 용적형 펌프 특성상 릴리이프 밸브에 대한 부분이 추가되었으며 이물질로 인한 펌프 내부의 파손을 방지하기 위한 스트레이너 설치 및 진공펌프 없이 작동하는 용적형 펌프와 원심펌프와의 차이점을 포함하고 있다. 이와같은 용적형 펌프의 인정기준 부분 추가로 인하여 초고층 빌딩 및 대형화재에서의 화재진압에 있어서 보다 다양한 화재 진압용 소방 장비의 선택과 능동적인 대응을 할 수 있을 것으로 기대되며, 이와같은 인정기준은 2016년 1월 제정되었다.

• 한국정보통신학회논문지
• /
• 제9권2호
• /
• pp.338-347
• /
• 2005

본 논문에서는 이동물체의 변위 예측을 위한 시간솎음 탐색 방향 알고리즘 제안하여 고속이동물체의 추적과 속도 측정을 하였다. 제안된 알고리즘은 이동물체의 이동 방향을 예측하기 위하여 초기 방향은 시간적으로 연속하는 과거 두 프레임에서 이동물체를 검출하고 이동 각도와 이동 거리를 구하여 초기화하였다. 현재 프레임에서 이동물체의 이동 방향은 시간솎음 탐색 방향 마스크를 적용하여 이동물체의 이동 방향을 구하였다. 시간솎음 탐색 방향 마스크는 연속 프레임에서 프레임을 시간 솎음하여 이동물체를 검출하고, 이동물체의 진행방향의 예측은 8 방향 중에서 이동물체의 이동 각도를 구하여 탐색 마스크를 결정하고, 탐색 마스크에 의해 이동물체의 이동 방향을 예측하였다. 제안한 알고리즘의 타당성을 입증하기 위하여 고속으로 주행 중인 자동차의 추적과 속도를 측정하고, 성능을 평가하기 위하여 전역탐색기법과 제안된 방법을 비교 평가하였다. 그 결과, 제안된 방법에서는 이동물체 변위 탐색 횟수가 평균 91.8$\%$ 감소하였고, 추적 처리 시간은 평균 32.1ms 임을 보임으로서 이동물체 추적을 실시간적으로 실행할 수 있음을 보였다.

• 대한기계학회논문집A
• /
• 제29권4호
• /
• pp.534-539
• /
• 2005

Nodal displacements are referred to the initial configuration in the total Lagrangian formulation and to the last converged configuration in the updated Lagrangian furmulation. This research proposes a relative nodal displacement method to represent the position and orientation for a node in truss structures. Since the proposed method measures the relative nodal displacements relative to its adjacent nodal reference frame, they are still small for a truss structure undergoing large deformations for the small size elements. As a consequence, element formulations developed under the small deformation assumption are still valid for structures undergoing large deformations, which significantly simplifies the equations of equilibrium. A structural system is represented by a graph to systematically develop the governing equations of equilibrium for general systems. A node and an element are represented by a node and an edge in graph representation, respectively. Closed loops are opened to form a spanning tree by cutting edges. Two computational sequences are defined in the graph representation. One is the forward path sequence that is used to recover the Cartesian nodal displacements from relative nodal displacement sand traverses a graph from the base node towards the terminal nodes. The other is the backward path sequence that is used to recover the nodal forces in the relative coordinate system from the known nodal forces in the absolute coordinate system and traverses from the terminal nodes towards the base node. One open loop and one closed loop structure undergoing large deformations are analyzed to demonstrate the efficiency and validity of the proposed method.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.993-1000
• /
• 2009

In general, a drilled shaft embedded in weathered rock has a large load bearing capacity. Therefore, most of the load tests are performed only up to the load level that confirms the pile design load capacity, and stopped much before the failure load of the pile is attained. If a reliable failure load value can be extracted from the premature load test data, it will be possible to greatly improve economic efficiency as well as pile design quality. The main purpose of this study is to propose a standard for judging the reliability of the failure load of piles that is obtained from extrapolated load test data. To this aim, eleven static load test data of load-displacement curves were obtained from testing of piles to their failures from 3 different field sites. For each load-displacement curve, loading was assumed as 25%, 50%, 60%, 70%, 80%, and 90% of the actual pile bearing capacity. The limited known data were then extrapolated using the hyperbolic function, and the failure load was re-determined for each extrapolated data by the ASCE 20-96 method (1997). Statistical analysis was performed on the reliability of the re-evaluated failure loads. The results showed that if the ratio of the maximum-available displacement to the failure-load displacement exceeds 0.6, the extrapolated failure load may be regarded as reliable, having less than a conservative 20% error on average. The applicability of the proposed standard of judgment was also verified with static load test data of driven piles.

• Structural Engineering and Mechanics
• /
• 제51권4호
• /
• pp.547-564
• /
• 2014

This study focuses on the application of an active tuned mass damper (ATMD) for controlling the seismic response of an 11-story building. The control action is achieved by combination of a fuzzy logic controller (FLC) and Particle Swarm Optimization (PSO) method. FLC is used to handle the uncertain and nonlinear phenomena while PSO is used for optimization of FLC parameters. The FLC system optimized by PSO is called PSFLC. The optimization process of the FLC system has been performed for an 11-story building under the earthquake excitations recommended by International Association of Structural Control (IASC) committee. Minimization of the top floor displacement has been used as the optimization criteria. The results obtained by the PSFLC method are compared with those obtained from ATMD with GFLC system which is proposed by Pourzeynali et al. and non-optimum FLC system. Based on the parameters obtained from PSFLC system, a global controller as PSFLCG is introduced. Performance of the designed PSFLCG has been checked for different disturbances of far-field and near-field ground motions. It is found that the ATMD system, driven by FLC with the help of PSO significantly reduces the peak displacement of the example building. The results show that the PSFLCG decreases the peak displacement of the top floor by about 10%-30% more than that of the FLC system. To show the efficiency and superiority of the adopted optimization method (PSO), a comparison is also made between PSO and GA algorithms in terms of success rate and computational processing time. GA is used by Pourzeynali et al for optimization of the similar system.