Tae-Young Chung

Study on the Parameter Decision of Spring-viscous Dampers for Torsional Vibration Reduction of Diesel Engine Shafting System

Excessive torsional vibrations from marine engine shafting systems can be reduced by using torsional vibration dampers. But in order to be tuned effectively, the dampers should be designed through the optimum design procedure. In this paper, the procedure to get the optimum values of system parameters of spring-viscous dampers using effective modal mass of inertia and stiffness is suggested and the damping is determined by the exact algebra optimization method. The validity of the suggested method is confirmed through the application to a 1800 kW four cycle diesel engine and generator system.

Derivation of 4 degrees of freedom nonlinear wind turbine model using effective mass and stiffness for simulation of control algorithm

As concern about limited energy is gradually growing and wind energy is regarded as one of the best solutions, research on the wind turbine system has been vigorously accomplished. The commercial tools to simulate the non-linear dynamic characteristics of the wind turbine system are various, but the tools take a significant amount of time to simulate the control algorithm and require many input variables. In this paper, the procedures to simulate and examine the controller of wind turbines at the initial design stage are proposed by a 4 degrees of freedom mathematical model of wind turbine, and methodology to make the turbine model is also proposed by effective mass and stiffness defined in the modal domain. The proposed method in this paper is simpler than other methods. The simulations by the three kinds of models for the 2-MW wind turbine are accomplished to discuss the simulation results: a 2 degrees of freedom wind turbine model without considering tower and blade behavior, a 4 degrees of freedom mod...

Study on 4-degree-of-freedom Mathematical Model for Simulation of Wind Turbine System at Initial Design Stage

The commercial tools to simulate the non-linear dynamic characteristics of wind turbine system are various but, the tool take much time to simulate the control algorithm and require many input variables. In this paper, the procedures to derive the simplified 4-degree-of-freedom mathematical model of a 2-MW wind turbine which could be used at the initial design stage of the controller are proposed based on RISO`s suggested method. In this model, the 1st tower fore-after bending motion and 1st blade flapping motion are also considered in addition to the rotor-generator rotation motion in the 2-DOF model. The effectiveness of the 4-DOF model is examined comparing with the 2-DOF model and verification of the simplified model is accomplished through modal analysis for whole wind turbine system.

A Study on the Stiffness Design for a Steel Spring Torsional Vibration Damper

Conditions of stiffness for a steel spring torsional vibration damper are difficult and ambiguous. Nevertheless correct estimation of stiffness is essential and important in the damper design for the damper to activate properly in the field. In this paper, to build up the estimation method of steel spring torsional vibration damper a miniaturized model was developed for modelling between a spring and inner star of the damper. The method obtained from the results through the experiment and analysis of it was applied to the prototype torsional damper.

A Review on the Blast Resistant Design for Glazing and Window Systems Subject to High-explosive Loadings

Anti-terrorism design for public buildings as well as military facilities is important to minimize the mass casualties from terrorist attacks. Also, well designed glazing and window systems can reduce the potential injury of human caused by scattering fragment of a glazing. In this paper, blast resistant design for glazing and window systems is investigated based on the U.S. Standard. The design procedures include minimum requirements for the design, standard practice for design evaluation of the glazing and standard test method for evaluation of the performance.

A Study on the Experimental Dynamic Identification of Cylindrical Oil Dampers in the Wide Frequency Range

ABSTRACT System identification for cylindrical oil dampers is carried out based on a series of dynamic experimental tests and theoretical approach for the analysis of the experimental data. Experimental tests are conducted using a specific hydraulic actuator in the wide frequency range from 10 Hz to 90Hz. From this study, it is confirmed that control force of the damper is composed of inertia, damping and restoring components. In general, both restoring and damping components are significant and comparable. However, the portion of the inertia components becomes more significant than to be negligible in the high frequency range. * 1. 서 론 오리피스를 이용한 유체 댐퍼(orificed oil damper)는 피스톤, 실린더 및 오리피스로서 구성되어 있다. 외부에서 진동과 같은 외부하중이 입력될 때 피스톤에 의해 상대 운동이 발생하고, 실린더 내부의 한 유실(chamber)에 있는 유체에 압력에너지로 전달되어짐에 따라 피스톤 반대방향에 위치하는 다른 유실로 연결되어진 좁은 틈새(오리피스)를 통하여 유체가 빠져나가면서 점성 저항에 의한 에너지로 소산됨으로써 감쇠력이 발생하는 원리를 가지고 있다. 자동차, 선박, 교량 등 수송기계시스템, 건축․토목구조물 및 산업설비의 다양한 형태의 진동 및 충격†교신저자; 정회원, 한국기계연구원E-mail : sjmoon@kimm.re.krTel : (042)868-7428, Fax : (042)868-7418* 정회원, 한국기계연구원** (주)세영인더스트리을 저감하기 위해 널리 사용되고 있다. 또한 선박 및 육상 수송 장비(예를 들면, 자동차, 전차 등)의 운전 중 엔진 및 프로펠러 추진축계에서 발생하는 비틀림 진동에 의해서 각 요소에 부가되는 과도한 진동의 저감 목적으로 비틀림 댐퍼를 사용한다. 대부분의 비틀림 댐퍼의 경우에도 오리피스내의 유체흐름에 의해서 발생하는 저항력이 감쇠력으로 작용한다. 추진축계의 진동은 일반적인 구조물이나 기계시스템의 진동과 달리 상대적으로 고주파수 영역에서 발생하고 있다. 유체 댐퍼와 관련된 연구동향을 살펴보면, 진동방지용 에너지 흡수장치인 점성 유체 댐퍼의 동적거동특성을 파악하기 위하여 분수도함수를 이용한 수치모델로 해석을 수행하고, 실험을 통하여 수치모델에 필요한 변수들을 결정한 연구가 있다

A Study on Conceptual Design of Anti-rolling Devices for 250 TEU Class Mobile Harbors

A Mobile Harbor is a new transportation platform which can load and unload has containers to and from very large container ships on the sea. Currently designed Mobile Harbor a catamaran type which is equipped with precisely controlled gantry crane on the deck, and can transport 250 TEUs at a time. Loading and unloading works by crane require very small motion of Mobile Harbor in waves, because it may be operated outside of harbors. In this project, applicability of both tuned-type anti-rolling tank and maglev-type active mass driver is studied as anti-rolling systems.

Active Control of Structural Vibration Using Linear Oscillating Actuator (LOA)

In this paper, an iron core type LOA is designed and analyzed electro-magnetically for the application to the active control of structural vibration as an active mass driver. Structural vibration is sensored by the accelerometer attached to the structure and reduced by the optimally controlled motion of active mass of LOA giving anti-phase inertia force to the structure. As a result, LOA is confirmed to be applied to the active control of the structural vibration as an servo actuator by controlling the position of armature accurately.