• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.28-28
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• 2002

가스터빈 엔진을 운용하는 데 있어서 가/감속율을 크게 하면 엔진성능 천이 시간은 짧으나 압축기에서의 서지나 터빈 입구온도의 급격한 상승이 발생할 수 있으며 가/감속율을 작게 하면 엔진은 안정적이나 천이시간이 길어지게 되어 결과적으로 엔진의 동적 응답성이 나빠지게 된다. 또한 압축기에서 발생할 수 있는 서지를 방지하기 위하여 압축기 서지 마진이 l0%∼20%인 서지 한계선(조정선)을 설정하여 엔진이 서지 한계선을 넘지 않도록 제어한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.1-9
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• 2017

The cryogenic nitrogen spray of a swirl injector has been numerically investigated using three dimensional LES turbulence model to analyze the dynamic characteristics under supercritical condition. To predict the precise nitrogen properties under supercritical condition, SRK equation of state, Chung's method for viscosity and thermal conductivity and Takahashi's correlation based on Fuller's theory for diffusion coefficient are implemented. The complex flow structures due to interaction between flow field and acoustic field are observed inside and outside the injector under supercritical condition. FFT, POD, and DMD techniques are employed to understand the coherent structures. By implementing the FFT, the dominant frequencies are identified inside and outside the injector. The coherent flow structures related to the dominant frequencies are visualized using the POD and DMD techniques. In addition, the DMD provides the damping coefficient which is related with the instability prediction.

• Journal of Hydrogen and New Energy
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• v.21 no.5
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• pp.460-469
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• 2010

To develop coal gasfication system, many studies have been actively conducted to describe the simulation of steady state. Now, it is necessary to study the gasification system not only in steady state but also in dynamic state to elucidate abnormal condition such as start-up, shut-down, disturbance, and develop control logic. In this study, a model was proposed with process simulation in dynamic state being conducted using a chemical process simulation tool, where a heat and mass transfer model in the gasifier is incorporated, The proposed model was verified by comparison of the results of the simulation with those available from NETL (National Energy Technology Laboratory) report under steady state condition. The simulation results were that the coal gas efficiency was 80.7%, gas thermal efficiency was 95.4%, which indicated the error was under 1 %. Also, the compositions of syngas were similar to those of the NETL report. Controlled variables of the proposed model was verified by increasing oxygen flow rate to gasifier in order to validate the dynamic state of the system. As a result, trends of major process variables were resonable when oxygen flow rate increased by 5% from the steady state value. Coal flow rate to gasifier and quench gas flow rate were increased, and flow rate of liquid slag was also increased. The proposed model in this study is able to be used for the prediction of gasification of various coals and dynamic analysis of coal gasification.

• Composites Research
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• v.32 no.5
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• pp.211-215
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• 2019

The cell culture process under in vitro condition is much different from the actual human body environment. Therefore, in order to precisely simulate the human body environment, a dynamic cell culture device capable of delivering mechanical stimulation to cells is essential. However, conventional dynamic cell culture devices require relatively complicated devices such as tubes, pumps, and motors, and the mechanical stimuli delivered is also simple. In this study, an electro-active polymer actuator as a driving component is introduced to design simply driven dynamic cell culture device without complicated components. The device is capable of delivering relatively complex mechanical stimuli to the cells.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.106.2-106.2
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• 2010

IGCC (Integrated Gasification Combined Cycle) plants are among the most advanced and effective systems for electric energy generation. From a control perspective, IGCC plants represent a significant challenge: complex reactions, highly integrated control to simultaneously satisfy production, controllability, operability and environmental objectives. While all these requirements seem clearly to demand a multivatiable, model predictive approach, not many applications can be easily found in the literature. This paper describes the IGCC dynamic simulation that is capable of simulating plant startup, shutdown, normal, and abnormal operation and engineering studies. This high fidelity dynamic models contain the detailed process design data to produce realistic responses to process operation and upset. And the simulation is used by engineers to evaluate the transient performance and produce graphical information indicating the response of the process under study conditions.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.73-76
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• 2004

자동 부하 전환 개폐기는 일반적으로 주 전원의 전압 상태를 감시하여 주 전원의 정전이나, 저 전압 이 감지 될 때 주 전원을 개방시키고, 예비 전원으로 신속하게 전환 시킬 수 있는 구동 메커니즘이 필요하며, 주 전원이 정상 상태로 복구되면 다시 예비 전원에서 주 전원으로의 신속한 전환이 요구 되어진다. 본 논문에서 연구되는 자동 부하 전환 개폐기의 구동부는 1개의 구동력으로 2개 선로의 스위치를 동시에 조작하게 할 수 있는 링크 구조와 동작 원리를 간지고 있으며, 이 동작을 안정적이고 신뢰도 높게 조작하기 위해서 개폐기 구동부의 동특성을 구현할 수 있는 동적 모델로 검증하여 재작하였다. 보다 정확한 모델 수립을 위하여 기구 동작 시에 발생하는 부품들 사이의 충돌, 마찰, 유연성 등의 많은 동적특성들을 정밀하게 모사 할 수 있는 유연 다물체 동역학을 적용하였으며, 검증하였다.

• Journal of the Korean Geotechnical Society
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• v.33 no.4
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• pp.47-56
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• 2017

Aseismic designs of pile-supported wharves are commonly performed utilizing simplified dynamic analyses, such as multi-mode spectral analyses. Simplified analyses can be useful for evaluating the limit state of structures. However, several pile-supported wharves, that have been damaged during past earthquakes, have shown that soil deformation and soil-pile dynamic interaction significantly affect the entire behavior of structures. Such behavior can be captured by performing nonlinear effective stress analyses, which can properly consider the dynamic interactions among the soil-pile-structure. The present study attempts to investigate the earthquake performance of a pile-supported wharf utilizing a three-dimensional numerical method. The damaged pile-supported wharf at the Kobe Port during the Hyogo-ken Nambu earthquake (1995) is selected to verify the applicability of the numerical modeling. Analysis results showed a suitable agreement with the observations on the damaged wharf, and the significant effect of excess pore pressure development and pile-soil dynamic interaction on the seismic performance of the wharf.

• Annual Conference of KIPS
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• 2016.04a
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• pp.479-481
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• 2016

원전에서 개발되는 계측제어 계통의 소프트웨어에 대한 평가를 위해서 발전소 상태를 모사하는 시뮬레이터를 활용하는 방법이 있다. 기존의 정적인 데이터만을 이용해서 수행하는 시험은 시스템의 성능을 정확하게 검증하는 데 한계가 있었지만 시뮬레이터에서 생성하는 입력 데이터를 계측제어 계통에 입력하여 시험을 수행하면 동적으로 변하는 상태를 구현할 수 있고, 계측제어 계통의 동작이 정확하게 수행되는 지 확인할 수 있다. 본 연구에서는 이러한 시뮬레이터를 기반으로 계측제어 계통의 시험검증 적합성 평가를 수행할 수 있는 환경을 구축하였고, 필요한 프로그램을 개발하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.5
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• pp.360-368
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• 2008

A lumped parameter model of Li-ion battery in hybrid electric vehicle(HEV) is constructed and system parameters are identified by using recursive least square estimation for different C-rates, SOCs and temperatures. The system characteristics of pole and zero in the frequency domain are analyzed with the parameters obtained from different conditions. The parameterized model of a Li-ion battery indicates highly dependent of temperatures. To estimate SOC and polarization voltage, a Luenberger state observer is utilized. The P- or PI-gains of observer based on a suitable natural frequency and damping ratio is adopted for the state estimation. Satisfactory estimation accuracy of output voltage and SOC is especially obtained by a PI-gain. The feasibility of the proposed estimation method is verified through experiment under the conditions of different C-rates, SOCs and temperatures.

• Journal of the Korea Convergence Society
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• v.3 no.4
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• pp.35-44
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• 2012

In this study, a simulation program is developed in order to investigate non steady-state cornering performance of 6WD/6WS special-purpose vehicles. 6WD vehicles are believed to have good performance on off-the-road maneuvering and to have fail-safe capabilities. But the cornering performances of 6WS vehicles are not well understood in the related literature. In this paper, 6WD/6WS vehicles are modeled as a 18 DOF system which includes non-linear vehicle dynamics, tire models, and kinematic effects. Then the vehicle model is constructed into a simulation program using the MATLAB/SIMULINK so that input/output and vehicle parameters can be changed easily with the modulated approach. Cornering performance of the 6WS vehicle is analyzed for brake steering and pivoting, respectively. Simulation results show that cornering performance depends on the middle-wheel steering as well as front/rear wheel steering. In addition, a new 6WS control law is proposed in order to minimize the sideslip angle. Lane change simulation results demonstrate the advantage of 6WS vehicles with the proposed control law.