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Free Vibration Analysis of Perforated Plate Submerged in Fluid
Myung Jo Jhung,Jong Chull Jo,Kyeong Hoon Jeong 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.9
An analytical method to estimate the coupled frequencies of the circular plate submerged in fluid is developed using the finite Fourier-Bessel series expansion and Rayleigh-Ritz method. To verify the validity of the analytical method developed, finite element method is used and the frequency comparisons between them are found to be in good agreement. For the perforated plate submerged in fluid, it is almost impossible to develop a finite element model due to the necessity of the fine meshing of the plate and the fluid at the same time. This necessitates the use of solid plate with equivalent material properties. Unfortunately the effective elastic constants suggested by the ASME code are found to be not valid for the modal analysis. Therefore in this study the equivalent material properties of perforated plate are suggested by performing several finite element analyses with respect to the ligament efficiencies.
Modal analysis of eccentric shells with fluid-filled annulus
Jhung, Myung Jo,Jeong, Kyeong Hoon,Hwang, Won Gul Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.14 No.1
Investigated in this study are the modal characteristics of the eccentric cylindrical shells with fluid-filled annulus. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier expansion, and their results are compared with those of finite element method to verify the validation of the method developed. The effect of eccentricity on the modal characteristics of the shells is investigated using a finite element modeling.
Fluid Bounding Effect on Natural Frequencies of Fluid-Coupled Circular Plates
Jhung, Myung-Jo,Park, Young-Hwan,Jeong, Kyeong-Hoon The Korean Society of Mechanical Engineers 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.9
This study deals with the free vibration of two identical circular plates coupled with a bounded or unbounded fluid. An analytical method based on the finite Fourier-Bessel series expansion and Rayleigh-Ritz method is suggested. The proposed method is verified by the finite element analysis using commercial program with a good accuracy The case of bounded or unbounded fluid is studied for the effect on the vibration characteristics of two circular plates. Also, the effect of gap between the plates on the fluid-coupled natural frequencies is investigated.
Natural vibration analysis of coaxial shells coupled with fluid
Jhung, Myung Jo,Choi, Young Hwan,Jeong, Kyeong Hoon Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.16 No.6
Investigated in this study are the natural vibration characteristics of the coaxial cylindrical shells coupled with a fluid. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier series expansion, and their results are compared with those of finite element method to verify the validation of the method developed. The effect of the fluid-filled annulus and the boundary conditions on the modal characteristics of the coaxial shells is investigated using a finite element modeling.
Jhung Myung Jo,Jang Changheui,Kim Seok Hun,Choi Young Hwan,Kim Hho Jung,Jung Sunggyu,Kim Jong Min,Sohn Gap Heon,Jin Tae Eun,Choi Taek Sang,Kim Ji Ho,Kim Jong Wook,Park Keun Bae The Korean Society of Mechanical Engineers 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.2
Performed here is a comparative assessment study for the probabilistic fracture mechanics approach of the pressurized thermal shock of the reactor pressure vessel. A round robin consisting of one prerequisite deterministic study and five cases for probabilistic approaches is proposed, and all organizations interested are invited. The problems are solved by the participants and their results are compared to issue some recommendation of best practices and to assure an understanding of the key parameters in this type of approach, like transient description and frequency, material properties, defect type and distribution, fracture mechanics methodology etc., which will be useful in the justification through a probabilistic approach for the case of a plant over-passing the screening criteria. Six participants from 3 organizations responded to the problem and their results are compiled and analyzed in this study.
Random Vibration Analysis of Control Element Assembly Shroud
Jhung Myung Jo,Kim Beom Shig 한국전산구조공학회 1996 한국전산구조공학회논문집 Vol.9 No.1
원자로 내부구조물을 구성하고 있는 중요한 구조물 중의 하나언 제어봉집합체 보호구조물-에 대한 랜덤진동 의 응답을 구하였다. 제어봉집합체 보호구조물은 본래의 설계로부터 많은 설계변동이 있었고 이에 대하여 많 은 우려가 제기되었던 바 본 논문에서는 정상상태에서의 랜덤하중에 대한 동적해석을 수행하여 그 응답윤 'JL 하였고 이들을 실험치와 비교, 검토하였으며 제어봉집합체 보호구조울이 구조적으로 안전함을 보였다. The Control Element Assembly(CEA) shroud is one of the most important components in the reac tor vessel internals for the nuclear power plant. Because of the severe modification from its original design the structural integrity of this component has been questioned. In an attempt to resolve this question, the response of the CEA shroud to a random loading in the actual operating condition is calculated analytically and experimentally and compared to the code allowables to show that it is structurally adequate and acceptable for the long term operation .
Modal Analysis of Conical Shell Filled with Fluid
Myung Jo Jhung,Jong Chull Jo,Kyeong Hoon Jeong 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.11
As a basic study on the fluid-structure interaction of the shell structure, a theoretical formulation has been suggested on the free vibration of a thin-walled conical frustum shell filled with an ideal fluid, where the shell is assumed to be fixed at both ends. The motion of fluid coupled with the shell is determined by means of the velocity potential flow theory. In order to calculate the normalized natural frequencies that represent the fluid effect on a fluid-coupled system, finite element analyses for a fluid-filled conical frustum shell are carried out. Also, the effect of apex angle on the frequencies is investigated.
Pressure-temperature limit curve for reactor vessel evaluated by ASME code
Jhung, Myung Jo,Kim, Seok Hun,Jung, Sung Gyu Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.14 No.2
A comparative assessment study for a generation of the pressure-temperature (P-T) limit curve of a reactor vessel is performed in accordance with ASME code. Using cooling or heating rate and vessel material properties, stress distribution is obtained to calculate stress intensity factors, which are compared with the material fracture toughness to determine the relations between operating pressure and temperature during reactor cool-down and heat-up. P-T limit curves are analyzed with respect to defect orientation, clad thickness, toughness curve, cooling or heating rate and neutron fluence. The resulting P-T curves are compared each other.
The Effect of Tributary Pipe Breaks on the Core Support Barrel Shell Responses
Jhung, Myung-Jo,Hwan, Won-Gul Korean Nuclear Society 1993 Nuclear Engineering and Technology Vol.25 No.2
Work on fracture mechanics has provided a technical basis for elimination of main coolant loop double ended guillotine breaks from the structural design basis of reactor coolant system. Without main coolant loop pipe breaks, the tributary pipe breaks must be considered as design bases until further fracture mechanics work could eliminate some of these breaks from design consideration. This paper determines the core support barrel shell responses for the 3 inch pressurizer spray line nozzle break which is expected to be the only inlet break remaining in the primary side after leak-before-break evaluation is extended to smaller size pipes in the near future. The responses are compared with those due to 14 inch safety injection nozzle break and main coolant loop pipe break. The results show that, when the leak-before-break concept is applied to the primary side piping systems with a diameter of 10 inches or over, the core support barrel shell responses due to pipe breaks in the primary side are negligible for the faulted condition design.