자기베어링 스테이지의 동적 거동 통합 시뮬레이션을 통한 제어 설계

김병섭(Byung-Sub Kim) 한국생산제조학회 2013 한국생산제조학회지 Vol.22 No.4

The dynamic simulation of machine tools and motion control systems has been widely used for optimization, design verification, control design, etc. There are three main streams in dynamic simulation: structural dynamic analysis based on the finite element method, dynamic motion analysis based on equations of motion, and control system analysis based on transfer functions. Generally, one of these dynamic simulation methods is chosen and employed for specific purposes. In this study, an integrated dynamic simulation is introduced, in which the structure, motion, and control dynamics are combined together. Commercially well-known software is used in the integrated dynamic simulation: ANSYS, ADAMS, and Matlab/Simulink. Using the integrated dynamic simulation, the dynamics of a magnetic bearing stage is analyzed and the causes of oscillation and noise are identified. A controller design for suppressing a flexible dynamic mode is carried out and verified through the integrated dynamic simulation.

화재시뮬레이션

김상문(Sang Moon Kim),윤상열(Sang Youl Yoon),김경천(Kyung Chun Kim) 한국가시화정보학회 2006 한국가시화정보학회지 Vol.4 No.1

Fire simulation has been developed for decades to analyze fire cases and provide a tool to study fundamental fire dynamics and combustion. There are three way of fire simulation which are a full scale simulation, an experimental simulation and a computational simulation. In case of a full scale simulation, because a higher cost, a higher risk, more efforts are needed, a demand for it has been decreased. But recently a demand for an experimental simulation and a computational simulation has been increased. A computational simulation has several advantages; lower cost, short period, many case studies, more visual results, a quantitative result and etc. FDS(Fire Dynamics Simulator) which has been developed in BFRL (Building and Fire Research Laboratory), NIST(National Institute of Standards and Technology) is a popular world wide code for fire simulation. Lack of accurate predictions by the model could lead to erroneous conclusions with regard to fire safety. All results should be evaluated by the informed judgment of the qualified user.

대규모 인구동태 시뮬레이션을 통한 에이전트 기반 고성능 시뮬레이터의 구현에 관한 연구

김민수,이지환,김영진 한국전자거래학회 2023 한국전자거래학회지 Vol.28 No.1

Agent-based simulation models the interaction of agents acting autonomously within a system in order to deeply understand the behavior and status of the target system. Agent-based simulation has the advantage that it is relatively easy to understand the detailed process of agent activity and the reason for its action, since the individual agent's decision-making can be reviewed in detail. However, since a large number of agents and complex interactions significantly degrade the execution performance of agent-based simulations, the number of agents and interactions are often reduced or simplified for actual simulations. Recently, as access to high-performance computing resources has become popular through continuous technological advancement, there is a growing demand for agent-based simulations to be executed on a real scale without model reduction. However, in order to effectively run large-scale agent-based simulations, significant modifications and development of related technologies are required in the implementation of agents and their interaction with the engine. In this study, by implementing and experimenting with a large-scale population dynamics simulation using the MASON open source solution, authors have examined which technical elements should be included in the development of a high-performance agent-based simulation engine in the future. In the process of speeding up the 120-year population dynamics simulation for the entire population of Korea from 2020, elements to be further developed or supplemented are summarized. It is expected that the results of this study will be of practical help in the implementation of high-performance agent-based simulation engines and the execution of large-scale models in the future. 에이전트 기반 시뮬레이션은 대상 시스템의 동작과 상태를 세부적으로 이해하기 위하여 시스템 내에서 자율적으로 행동하는 에이전트들의 상호작용을 모델링한다. 에이전트 기반의 시뮬레이션에서는 개별 에이전트의 의사 결정을 자세히 검토할 수 있으므로, 에이전트 활동의 세부 과정과 동작 이유를 이해하기가 상대적으로 쉽다는 장점이 있다. 하지만 많은 수의 에이전트와 복잡한 상호작용은 에이전트 기반 시뮬레이션의 실행 성능을 크게 떨어뜨리기 때문에, 실제 시뮬레이션의 수행을 위해서는 에이전트의 수와 상호작용을 축소하거나 단순화하는 경우가 많았다. 최근에는 지속적인 기술 발전을 통해 고성능 컴퓨팅 자원에 대한 접근이 대중화되면서 에이전트 기반 시뮬레이션을 모델의 축소 없이 실제 규모로 실행하고자 하는 요구가 커지고 있다. 그러나 막대한 규모의 에이전트 기반 시뮬레이션을 효과적으로 실행시키기 위해서는 에이전트의 구현 방식과 엔진과의 상호작용에서 상당한 수정 작업과 관련 기술의 개발이 필요하다. 본 연구에서는 MASON 오픈소스 솔루션을 활용하여 대규모 인구동태 시뮬레이션을 구현하고 실험해 봄으로써, 어떠한 기술 요소가 향후 고성능 에이전트 기반 시뮬레이션 엔진의 개발에 포함되어야 할 것인지를 살펴보았다. 2020년 대한민국 전체 인구에 대한 120년간의 인구동태 시뮬레이션을 고속화하는 과정을 통해 추가 개발되거나 보완되어야 할 요소들을 정리하였다. 본 연구의 결과가 향후 고성능 에이전트 기반 시뮬레이션 엔진의 구현과 대규모 모델의 실행에 실질적인 도움이 될 것으로 기대한다.

농업용 트랙터의 차축 구동 토크 예측을 위한 동역학 시뮬레이션 모델 개발

전현호,백승민,백승윤,김용주 대한기계학회 2023 大韓機械學會論文集A Vol.47 No.11

농업용 트랙터는 시장 수요에 맞게 지속적으로 개선 및 개발되고 있다. 이러한 과정에서 트랙터는 다양한 설계 변경이 이루어진다. 설계 변경에 따라 내구성 확보를 위해서는 반드시 성능평가가 수행되어야 한다. 농업기계분야에서는 대부분 시제품을 이용한 성능평가들이 이루어지고 있으며, 이는 많은 시간과 비용을 필요로 한다. 이를 해결하기 위해 최근 시뮬레이션 모델을 이용한 성능평가에 대한 연구가 다양하게 수행되고 있다. 따라서 본 연구에서는 농업용 트랙터의 성능평가를 위해 동역학 시뮬레이션 모델을 개발 및 검증에 대한 연구를 수행하였다. 시뮬레이션 모델 개발은 타이어 계수 측정 시스템 및 계측용 트랙터 개발을 통해 수행되었다. 트랙터 모델 구성은 차량의 제원 및 상용프로그램인 Recurdyn(V9R4, Functionbay Co. Ltd., Korea)을 이용하여 수행하였다. 모델 검증은 시뮬레이션 결과 값 및 계측 값의 평균 차축토크 비교 분석을 통해 수행하였으며, 분석결과 6%의 오차를 보였다. 해당 모델을 이용하여 트랙터의 차축 부하 예측이 가능할 것으로 판단되며, 본 모델은 차후 연구에서 쟁기 및 로타리 등 주요 트랙터 작업 조건에서의 차축 부하 예측에 활용할 예정이다. Agricultural tractors are continuously being developed to improve performance. In this process, the tractor design has to be changed. To secure durability according to the design change, performance evaluation has to be conducted. Performance evaluation using prototypes is mostly conducted in agricultural machinery, which requires a lot of time and money. Various studies on performance evaluation using simulation models have been recently conducted to solve this problem. Therefore, this study is conducted to develop and validate a dynamic simulation model for the performance evaluation of agricultural tractors. The development of the simulation model is conducted through the development of a tire stiffness and a tractor measurement system. The tractor model is configured using the commercial program for dynamics simulation. The simulation model is validated through a comparison of the average axle torque of the simulation result and measurement data. It shows that there was an error of 6. It is deduced that it is possible to predict the axle torque of the tractor using the dynamic simulation model of an agricultural tractor. In future, studies will be conducted using this simulation model to predict the axle torque in conditions of tractor operation such as the plow and rotary tillage.

시스템다이내믹스 시뮬레이션에서의 동적 최적화에 관한 연구

남광식,문성암 한국시스템다이내믹스학회 2022 한국시스템다이내믹스 연구 Vol.23 No.4

For the optimization of system dynamics simulation, only one optimal policy has been calculated through simulation by applying static optimization. This method does not reflect the reality that the policy changes depending on the point of time, so it may not be the optimal value at a specific point in time. Therefore, this study proposes a method to calculate the optimal policy for each time point by using dynamic optimization in the system dynamics simulation. For the simulation, a fixed order quantity inventory management model was built using the system dynamics software (Vensim). Dynamic optimization was limited in implementation in Vensim, so the optimal reorder point (ROP) was calculated at each time point using data analysis software (Python). This study is meaningful in that it presented a method to apply dynamic optimization in system dynamics simulation by linking Vensim and Python. It is expected that it will be used as a tool to support real-time policy making in public institutions and the private sector in the future.

열통합 증류 공정의 상세 동적 모델링 및 모사

박병학,이희승,문일 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.1

열통합된 연속식 증류탑에 대해 각 장치에서의 물질수지와 에너지 수지는 물론 비선형 Hydraulic 방정식과 열역학적 관계식을 고려해 상세 동적 모델링을 수행하였으며 연속/이산 변수가 혼합된 모델의 동적모시를 통해 계의 동특성을 연구하였다. 대상 공정은 벤젠과 톨루엔의 2성분계를 선택하였는데 모델링을 통해 1,062개의 미분대수 방정식으로 수식화하였다. 동적모사의 결과 증류탑을 구성하고 있는 각 장치에서의 온도, 압력, 조성 및 액상과 기상의 몰당 유속에 대한 동적거동의 수치적 해를 얻을 수 있었다. 본 연구의 특징은 에너지 절감을 위해 개조 설계된, 즉 열통합을 고려한 연속식 증류탑의 동적모사를 통해 기존의 연속식 증류탐과의 성능비교를 했다는 점이다. 공정의 개시운전에서 정상상태에 이르기까지. 그리고 제품의 생산이 시작되는 시점에서 또 다른 정상상태에 이르는 일련의 과정을 동적모사하여 열통합 증류공정이 기존의 증류공정보다 에너지 절감의 측면에서 효율이 높다는 것을 증명하였다. 이전의 연구에서는 정상상태 모사를 통한 검증은 있었으나 비정산 상태를 고려한 동적모사를 통한 검증은 이루어지지 않았다. 또한 증류탑 이외에도 재비기, 환류드럼, 펌프, 밸브, 디지털 제어기 등의 주변장치에 대한 동적모델링을 수행함으로써 전체 공정의 운전절차를 동적모사에 반영할 수 있도록 하였다. A rigorous dynamic modeling and dynamic simulation are performed to find the dynamic behaviour of a distillation column model including continuous/discrete variables, considering material balances, heat balances, nonlinear hydraulic equations and themodynamic correlations in all equipments. Target process of this study is a distillation column aimed at separating benzene and toluene. Through dynamic modeling, 1,062 differential algebraic equations are acquired. Numerical solutions of dynamic behaviour such as pressure, temperature, fraction and molar flow rate in liquid and vapor phase. The feature in this study is to compare the energy consumption of a conventional distillation column with that of a heat integrated distillation column using dynamic simulation method. This study verifies energy efficiency through dynamic simulation in series of start-up of processes. There are some verifications of a heat integrated distilation column in view of steady state simulation but no verification in view of dynamic simulation. Also, this study considers operating procedures of the process in dynamic simulation through modeling of all equipments such as reboilers, refluxdrums. pumps, valves, digital PI controllers etc.

A Dynamic Test Facility for Mobile Air Conditioning Systems

Amr Gado,Yunho Hwang,Reinhard Radermacher 대한설비공학회 2007 International Journal Of Air-Conditioning and Refr Vol.15 No.4

Mobile air conditioning systems work under widely changing operating conditions. To understand the system behavior under such dynamic conditions, a test facility that can impose transient loads as well as conducting dynamic measurements is needed. To test mobile air conditioning systems including their dynamic performance under various drive cycle patterns without using full scale vehicles in a wind tunnel, a new test facility, called "dynamic simulator," is described. It can replicate real vehicle operating conditions by interacting with the system being tested based on the measured system performance and subsequently adjusting the air properties returning to the test system based on the results of a numerical cabin model. A new dynamic simulator has been designed, constructed, and verified for performing dynamic tests. It was successful in controlling the temperature and relative humidity of the air returning to the test unit within ± O.7℃ and ± 4% of their respective intended values. The verification test under the New European Driving Cycle demonstrated that detailed transient behavior of the mobile air conditioning system could be measured by using this dynamic simulator.

역학 기반 이산 사건 시뮬레이션을 위한 다물체계 동역학 커널 개발

구남국,조아라,Martin Friebe,이규열,노명일 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.11

There are several kinds of mechanical systems that are under event-triggered conditions. For the dynamic analysis of such mechanical systems, a simulation program that can generate equations of motion for mutibody systems in the discrete-event simulation framework was developed. For complex multibody systems, a dynamics kernel was developed to generate the equations of motion for multibody systems based on multibody dynamics. To generate the equations of motion, the recursive formulation method was used. Using the developed dynamics kernel, the dynamic responses of multibody systems can be carried out under continuous conditions. The general multibody dynamics kernel, however, cannot deal with discontinuous-state variables and event-triggered conditions. The multibody dynamics kernel, therefore, was integrated into the discrete-event simulation program to deal with multibody systems in discontinuous environments. The discrete-event simulation program was developed based on the discrete-event system specification (DEVS) formalism, which is a modular and hierarchical formalism for analyzing systems under event-triggered conditions.

독일 아이펠의 지역적 관리에 따른 유럽너도밤나무 숲의 생장변화 추정을 위한 시뮬레이션 개발

변재균,마티나 로스 니콜,리차드 오터만스 한국시뮬레이션학회 2024 한국시뮬레이션학회 논문지 Vol.33 No.1

숲을 체계적으로 관리하고 경영하기 위해서는 나무생장 변화에 대한 신뢰성 있는 예측이 필요하다. 독일의 아이펠 지역에서는 주요 목재종인 유럽너도밤나무가 식재되어 관리되어 지고 있다. 본 지역의 산림관리자의 실제 산림경영의 경험과 조언을 토대로, 다양한 산림 관리에 따른 단기 및 장기 효과를 예측하고자 지역 특수성을 지니는 시뮬레이션 모델의 접근방법을 개발하고자 하였다. 시뮬레이션 모델은 (1) 묘목 생성, (2) 나무 사멸 조절 (3) 나무 생장의 세 가지 모듈로 구성된다. 산림관리자에 의해 제공된 너도밤나무 숲의 실제 부피 변화를 근사화하기 위해 다양한 변수(나무수, 나무간 거리, 씨앗의 분포, 경쟁)를 반복적으로 수정하여 세 가지 모듈을 결합한 하이브리드 시뮬레이션 모델을 개발할 수 있었다. 본 연구를 통해 유럽너도밤나무 숲의 350년을 모의하여 생장 변화를 예측하였으며, 아이펠 지역의 세 가지 다른 관리 방법 (숲을 보호한 상태에서 목재벌채, 선택적 벌목, 보호림) 시나리오를 적용하였을 때 모의된 결과를 비교하였다. 시뮬레이션 결과를 통해 나무 생장의 변화가 현실적으로 잘 반영되었다는 것을 확인할 수 있었으며, 미래에 장기간 실제 축적된 산림 데이터를 획득하여, 검증과 보정의 과정을 반복한다면 더 높은 정확도의 지역 맞춤형 모델이 개발될 수 있을 것으로 사료된다. Forest management is known to beneficially influence stand structure and wood production, yet quantitative understanding as well as an illustrative depiction of the effects of different management approaches on tree growth and stand dynamics are still scarce. Long-term management of beech forests must balance public interests with ecological aspects. Efficient forest management requires the reliable prediction of tree growth change. We aimed to develop a novel hybrid simulation approach, which realistically simulates short- as well as long-term effects of different forest management regimes commonly applied, but not limited, to German low mountain ranges, including near-natural forest management based on single-tree selection harvesting. The model basically consists of three modules for (a) natural seedling regeneration, (b) mortality adjustment, and (c) tree growth simulation. In our approach, an existing validated growth model was used to calculate single year tree growth, and expanded on by including in a newly developed simulation process using calibrated modules based on practical experience in forest management and advice from the local forest. We included the following different beech forest-management scenarios that are representative for German low mountain ranges to our simulation tool: (1) plantation, (2) continuous cover forestry, and (3) reserved forest. The simulation results show a robust consistency with expert knowledge as well as a great comparability with mid-term monitoring data, indicating a strong model performance. We successfully developed a hybrid simulation that realistically reflects different management strategies and tree growth in low mountain range. This study represents a basis for a new model calibration method, which has translational potential for further studies to develop reliable tailor-made models adjusted to local situations in beech forest management.

MD 시뮬레이션을 이용한 실린더 형태 나노와이어의 접촉면적에 관한 연구

김현준(Hyun-Joon Kim) 한국트라이볼로지학회 2016 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.32 No.1

Contact between solid surfaces is one of the most important factors that influence dynamic behavior in micro/nanoscale. Although numerous theories and experimental results on contact behavior have been proposed, a thorough investigation for nanomaterials is still not available owing to technical difficulties. Therefore, molecular dynamics simulation was performed to investigate the contact behavior of nanomaterials, and the application of conventional contact theories to nanoscale was assessed in this work. Particularly, the contact characteristics of cylindrical nanowires were examined via simulation and contact theories. For theoretical analysis, various contact models were utilized and work of adhesion, Hamaker constant and elastic modulus those are required for calculation of the models were obtained from both indentation simulation and tensile simulation. The contact area of the cylindrical nanowire was assessed directly through molecular dynamics simulation and compared with the results obtained from the theories. Determination of the contact area of the nanowires was carried out via simulation by counting each atom, which is within the equilibrium length. The results of the simulation and theoretical calculations were compared, and it was estimated that the discrepancy in the results calculated between the simulation and the theories was less than 10 except in the case of the smallest nanowires. As the result, it was revealed that contact models can be effectively utilized to assess the contact area of nanomaterials.