A method for evaluating the safety of the corrosion fatigue of a high-pressure (HP) drum for the heat recovery steam generator (HRSG) is presented through a transient thermal stress analysis. To evaluate the corrosion fatigue, European Standard EN 13445-3 is applied to check whether the magnetite protective layer on the water-contacting surface can be preserved during the transient operating conditions: cold start, hot start, warm start, and load change. Static analysis is performed to analyze the stress due to the operating pressure, and transient thermal and structural analyses are performed for the transient operating conditions. As per EN 13445-3, the analyzed maximum and minimum stresses of the transient operating conditions at representative locations are compared with the allowable limits derived from the stress due to the operating pressure. In conclusion, the magnetite protective layer was preserved under the transient operating conditions and the HP drum was found to be safe for the corrosion fatigue. The method of analyzing the thermal stress and evaluating the safety of the corrosion fatigue presented in this research can be applied effectively in the design stage of various unfired pressure vessels exposed to high temperature and high pressure loading.

In this work, vibration characteristics of a flue gas cooler(FGC) for a heavy oil upgrading are experimentally analyzed and an effective method is proposed to reduce the vibration level. Firstly, the vibration under the operation condition of the FGC is measured and analyzed to identify the generation phenomena of vibration. And the displacement of the outer wall of the FGC is also analyzed to identify dominant frequencies of vibration. Secondly, an effective design to reduce the vibration is suggested by using the modal analysis. Consequently an improved design of the FGC gas cooler, which has lower vibration level, is obtained and then verified though the analysis and test.

Optimal design of a roller rail which replaces the ball rail for three-door refrigerators is presented using the finite element analysis and the Taguchi method. Stress and deformation of the roller rail for an initial design are analyzed and evaluated. Optimal design parameters are determined using the Taguchi method. The maximum stress of the optimal design is favorably reduced comparing to the initial design. It is verified through an additional analysis that the drawer on the roller rail will not be derailed even if one opens the drawer with a transverse force.

Behavior of a package of a microwave oven under the clamping condition is evaluated by tests and the finite element analyses. PAM-CRASH software is used for the finite element analyses. Results of the analyses are compared with those of the tests and accuracy is shown to be favorable. Under the clamping condition of the original design, severe deformation occurs and an improved design of the outer case and upper EPS(Expandable Poly Styrene) is proposed to reduce it. Face beads of the outer case are introduced and shape of the upper EPS is modified to reduce the deformation resulting from the clamping load. The improved design model is analyzed and its deformation is shown to be satisfactory. A prototype is produced according to the improved design and tests are performed. Results of the clamping test of the prototype show that the plastic deformation is removed totally.

The Taguchi method is applied to obtain the optimal design of an automotive pedal arm in consideration of the stiffness test specification. Design parameters are defined to describe shape of the pedal arm. Volume, maximum Von-Mises stress and maximum displacement of the pedal arm are established as the smaller-the-better characteristics. Optimal parameters are determined on the basis of the analyzed level averages of the characteristics.

To minimize the possible leakage of microwave when one opens the door of a microwave oven during its operation, a structural design of the reinforcing brackets for the door frame is presented. Twisting deformation of the door frame resulting from a dynamic pulling force is analyzed by harmonic and transient response analyses. Several types of the reinforcing brackets weldable to the right flange of the door frame is taken into consideration, and their effects to the twisting deformation of the door frame are compared and evaluated. As a conclusion, a thick step-shaped bracket, which is welded to whole length of the right flange, is favorable.

This study focuses on a performance improvement of the vent silencer using acoustic analysis. Since the vent silencer is generally used for a high level shock noise, it should be designed to reduce a wide frequency band noise. In the designing stage of the vent silencer, structural shapes of diffuser and splitter are the most significant design parameters. Effects of modifying the original structure of the diffuser and the splitter are analyzed and evaluated. From the results, It is found that the diffuser with two pipes and double-step structure more effectively reduces a wide frequency band noise but the increment of the number of splitters is not desirable.

Responses of the cabinet of the reactor safety system under seismic loadings are analyzed, its dynamic characteristics and structural reliability being evaluated. Analyzed natural frequencies are compared with those measured from a resonance test. Structural safety of the cabinet is evaluated in consideration of the required response spectrums of the operation-base and safe-shutdown earthquakes. Transient responses of the cabinet are analyzed with input ground acceleration measured during the seismic test, accelerations being extracted at the locations of the main internal parts. The transient responses are compared with those from the seismic test, favorable results being shown.

When one opens the door of a microwave oven during operation, microwave might leak through the clearance of the door. Present research has been motivated by the need to reduce the possible clearance by enhancing torsional stiffness of the door of the microwave oven. Static deformation of the door frame of the oven is analyzed under a door-opening force. On the basis of the topological optimization, the right flange of the door frame is shown to need reinforcing. Several types of reinforcing brackets weldable to the right flange is proposed, and their effects to the stiffness of the door frame are compared and evaluated.

The present research deals with structural analysis and optimal design of the heating drum of a hot-rolling press for medium density fiberboard. Stress concentration in the journal of the heating drum is analyzed by the submodel technique of the finite element method. The fatigue life under operating conditions is analyzed and evaluated by the stress-life theory. Shape optimal design problems, to minimize the maximum stress occurring in the journal, are formulated and shape parameters of the comer fillets of the journal are defined as the design variables. The problems are solved by the numerical optimization method and optimal shapes are found. The optimal designs are shown to be reliable in terms of the maximum stress and the fatigue life.