Papers by Author: Hyun Soo Kim

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Authors: Young Shin Lee, Hyun Soo Kim, Young Jin Choi, Jae Hoon Kim
Abstract: The laminated composite structures applied to the wing and the speed brake of an aircraft or the turbine blade of a compressor. These structures may be impacted by birds and hails during operation. They may also be impacted by drop of a tool during manufacture or repair. Unlike high velocity impact damage, which can be easily found by the naked eye, the damage due to low velocity impact may be difficult to detect. Damage which is not detected may cause failure of a structure and result in damage propagation. Growth of damage means reduction of stiffness on the structure. So, exact prediction of damage caused by a low velocity impact is very important in order to guard against sudden failure of the structure. In this study, modified delamination failure criterion has suggested in order to predict the failure behavior of a composite plate subjected to low-velocity impact. The criterion includes the assumption which is matrix cracking mode causes delamination failure. Predicted damage using supposed delamination criterion is similar to experiment results.
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Authors: Young Jin Choi, Young Shin Lee, Jae Hoon Kim, Won Shik Park, Hyun Soo Kim
Abstract: The hot gas casing of the gas turbine has operated in high temperatures and thermal gradients. The structure safety of hot gas casing will be highly depend on the thermal stress. In this paper, flow and thermal stress analysis of the hot gas casing is carried out using ANSYS program. The obtained temperature data by flow analysis of hot gas casing is applied to the load condition of the thermal analysis. The thermal stress analysis is carried out the elastic-plasticity analysis. The pressure, temperature and velocity of the flow and thermal stress of the hot gas casing are presented
169
Authors: Young Shin Lee, Hyun Soo Kim, C.H. Han
Abstract: An experimental modal analysis is the process to identify structure's dynamic characteristics. For investigating vibrational characteristics of cylindrical shell with multiple supports, modal testing is performed using impact exciting method. The frequency response function(FRF) measurements are also made on the experimental model within the frequency range from 0 to 4kHz. Modal parameters are identified from resonant peaks in the FRF’s and animated deformation patterns associated with each of the resonances are shown on a computer screen. The experimental results are compared with analytical and FEA results.
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Authors: Jae Hoon Kim, Duck Hoi Kim, Young Shin Lee, Young Jin Choi, Hyun Soo Kim, Won Shik Park
Abstract: Low cycle fatigue tests are performed on the Inconel 617 super alloy that be used for structural material of hot gas casing for gas turbine. The relations between strain energy density and number of cycles to failure are examined in order to predict the low cycle fatigue life of Inconel 617 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. And, the cyclic behavior of the Inconel 617 super alloy is characterized by cyclic hardening with increasing number of cycles.
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Authors: Young Shin Lee, Hyun Soo Kim, Yong Jae Kim
Abstract: The package used to transport radioactive materials, which is called by cask, must maintain the structural integrity for the requirements of hypothetical accident conditions, 9m free drop of the thick plate impact. These requirements for the cask design should be verified through test or finite element analysis to confirm the regulatory guide. In this paper, three dimensional impact analysis using ABAQUS/Explicit code under 9m free drop of the thick plate impact condition for the KSC-4 cask is performed. As the results, maximum stress intensity on each part of the cask and deformation shape of the cask is calculated and the structural intensity of the cask is evaluated by NRC Regulatory Guides.
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Authors: Young Shin Lee, Hyun Soo Kim, Young Jin Choi, Jae Hoon Kim, Jeong Sik Yim
Abstract: A fuel channel, which is the major structure of a nuclear reactor, is excited by the flow of cooling water during the operation of the nuclear reactor. This flow of cooling water can cause excessive vibration of the structure by the resonance. So, in the design process of a nuclear structure, the exact evaluation of the effect of water to modal characteristics and stiffness characteristics is very important to generate an exact analysis model. In this study, the effect of water height for modal characterisics of the fuel channel is investigated and the stiffness evaluation of that is conducted using the modal test results.
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Authors: Young Shin Lee, Hyun Soo Kim, Young Jin Choi, Jae Hoon Kim
Abstract: This study is conducted in order to estimate the structural characteristics for inlet port of air breathing engine under flight condition at 12 ~ 15 km height and Mach Number 2 ~ 4. Inlet port of air breathing engine is heated up from 307 oC to 427 oC, so that is reached plastic zone partially. The material properties at high temperature such as young’s modulus, thermal expansion coefficients and thermal conductivity are applied to the analysis. The transient temperature and stress analysis are performed by the finite element method using nonlinear commercial code ABAQUS. The analysis is performed for the two materials, Titanium alloy and AISI4130 Steel and two FEM element type, shell and solid, to select preliminary design model for flight condition. Thermal boundary conditions are applied at inlet port until 5 s, and these conditions are maintained until 150 s. The results of the analysis recommend tendency of thermal stress and temperature contour. This study is expected useful to select the structural material and to determine shape of air inlet port of air breathing engine which satisfied the structural design safety.
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