• Journal of the Korean Geotechnical Society
• /
• v.32 no.9
• /
• pp.51-62
• /
• 2016

Parametric studies for various site conditions by using 3d numerical model were carried out in order to estimate dynamic behavior of soil-pile-structure system in dry soil deposits. Proposed model was analyzed in time domain using FLAC3D which is commercial finite difference code to properly simulate nonlinear response of soil under strong earthquake. Mohr-Coulomb criterion was adopted as soil constitutive model. Soil nonlinearity was considered by adopting the hysteretic damping model, and an interface model which can simulate separation and slip between soil and pile was adopted. Simplified continuum modeling was used as boundary condition to reduce analysis time. Also, initial shear modulus and yield depth were appropriately determined for accurate simulation of system's nonlinear behavior. Parametric study was performed by varying weight of superstructure, pile length, pile head fixity, soil relative density with proposed numerical model. From the results of parametric study, it is identified that inertial force induced by superstructure is dominant on dynamic behavior of soil-pile-structure system and effect of kinematic force induced by soil movement was relatively small. Difference in dynamic behavior according to the pile length and pile head fixity was also numerically investigated.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.1 no.1
• /
• pp.24-32
• /
• 1997

A nonlinear dynamic simulation of a small gas turbine engine was performed by using DYNGEN program with various environmental conditions. It was observed that the effect of the bleed air flow rate changed to overall engine performance. The real time linear model which was a function of engine rotor speed was resulted to be close to nonlinear simulation results. For optimal LQR controller, it was considered only fuel flow rate or both fuel flow rate and bleed air rate as inputs. In the comparison of both results, the LQR controller with multi input had better performance than that with single input.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1997.04a
• /
• pp.55-60
• /
• 1997

A nonlinear dynamic simulation was performed by using DYNGEN program with various environmental conditions. It was observed that the effect of the bleed air flow rate changed to overall engine performance. The real time linear model which was a function of rpm was resulted to be close to nonlinear simulation results. For optimal LQR controller, it was considered only fuel flow rate or both fuel flow rate and bleed air rate as inputs. In the comparison of both results, the LQR controller with multi input had better performance than that with single input.

• Membrane Journal
• /
• v.20 no.3
• /
• pp.228-234
• /
• 2010

In this study, dynamic simulation of membrane reactor was performed for water gas shift reaction and temperature, hydrogen concentration, etc. were investigated as a function of time and position. Simulation results indicated that differences of hydrogen concentration, hydrogen partial pressure, and temperature in the radial direction, were larger in the entrance than in the exit. In addition, the hydrogen flux was the largest in the entrance, where the hydrogen partial pressure difference was the largest, and the conversion of carbon monoxide in the exit was about 0.65.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2003.10a
• /
• pp.257-260
• /
• 2003

Dynamic simulation program for a smart UAV turbojet engine was developed. The transient simulation program utilized the CMP(Constant Mass flow) method and Euler integration method for integration of excess torque. The transient performance analysis was carried out by increasing from the idle to the maximum rotational speed of the gas generator. To observe engine dynamic behavior, fuel flow was monitored through a step and a ramp increase. When the fuel was increased as a step function the overshoot of the turbine inlet temperature exceeded the limit temperature.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1998.04a
• /
• pp.11-11
• /
• 1998

다목적으로 활용할 수 있는 터보축 엔진의 개발을 위한 정상상태 및 동적모사 프로그램을 개발하였다. 개발비, 개발시간, 개발위험도의 절감을 위해 가스발생기 부분은 성능이 잘 알려진 기존의 터보제트 엔진을 활용하였으며 약 3000hr 이상의 수명을 확보하기 위해 터빈재질을 교체하고, Larson-Miller 곡선을 이용하여 최대회전속도와 최대 터빈 입구온도를 각각 35000 RPM과 1140 K의 결정하였다 추가되는 동력터빈의 구성품 성능선도는 압축기 터빈 성능선도를 축척하여 사용하였다. 정상상태 성능해석에는 유량 및 일평형 방정식을 이용하였으며, 동력터빈이 각각 73%, 80%, 90%, 100% RPM일 때 가스발생기를 75%(24500 RPM)에서 100%(35000 RPM)까지 5% 간격으로 나누어 계산을 수행하였다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.8
• /
• pp.3774-3778
• /
• 2012

A dynamic simulation of a fully thermally coupled distillation is conducted for the design of a possible operation scheme, and its performance is examined with an example process of reformate fractionation process. The outcome of the dynamic simulation indicates that the column can be operated by using a $3{\times}3$ control structure. The structure consists of three controlled variables of the compositions of overhead, side products and bottom and three manipulated variables of the flow rate of reflux, liquid split ratio between a main column and a prefractionator and steam.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1998.10a
• /
• pp.37-37
• /
• 1998

중형항공기용 터보펜 엔진의 성능모사와 LQR 제어기 설계에 대한 연구를 수행하였다. 동적 성능모사를 설계점으로 선정한 지상최대이륙조건과 탈설계점으로 선정한 최대상승조건과 순항조건에 대하여 Step 증가, Ramp 증가, Ramp 감소, Step증가 후 Ramp 감소의 4가지 연료공급에 조건에 대하여 수행되었다. 성능모사 결과 모든 비행조건에서 연료를 Step 증가시킬 경우 고압터보빈의 입구온도가 제한온도인 3105$^{\circ}$R을 초과함을 확인하였고, 최대 상승조건에서 연료를 Step 증가시킬 경우가 4.5초 이내에 Ramp 증가시킬 경우 고압압축기에 서지가 발생함을 확인하였다. 따라서 고압터어빈의 오버슈트와 고압압축기의 서지를 동시에 제어할 수 있는 다변수 제어기의 설계가 필요함을 확인하였다.

• Proceedings of the Korea Society of Information Technology Applications Conference
• /
• 2002.06a
• /
• pp.97-98
• /
• 2002

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1998.10a
• /
• pp.69-74
• /
• 1998