• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.49-54
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• 2010

Fretting wear behavior under elastic deformable contacts was experimentally examined by using a simulated dual cooled fuel rod and its supporting structure. As this fuel rod has larger outer diameter than the typical solid rod to accommodate sufficient internal flow, new supporting structure geometries should be designed and their reliabilities (i.e. vibration characteristics, fretting wear resistance, etc.) are also examined with both analytical and experimental methods. In this study, the supporting structure characteristics and fretting wear behaviors are analyzed and examined by using one of the supporting structure candidates which has an embossing shape. The supporting structure characteristics were examined by using a specially designed test rig and their results were compared with that of analytical method. Based on the test results, the relationship between the supporting structure characteristics and their fretting wear behaviors was discussed in detail.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.4
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• pp.414-420
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• 1985

The melting phenomenal of the horizontal cylindrical ice-bar submerged in water are experimentally investigated for the temperature range from 2.5.deg. C to 15.deg. C. The shapes of the melting ice-bar are recorded by the Photo-elasticity Apparatus with modification of the test section. The shadowgraphs of the melting ice-bar show that water adjacent to the bar flows upward for the temperature range from 2.5.deg. C to 5.6.deg. C while above the temperature of 5.6.deg. C the flow is downward direction. The local and average Nusselt numbers become minimum at 5.6.deg. C which is considered as a critical temperature and the Nusselt numbers increase as temperature difference from the critical temperature increase.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.201-206
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• 2011

A spacer grid assembly is one of the most important structural components of the nuclear fuel assembly of a pressurized water reactor (PWR), and it affects the performance of the fuel assembly. The primary design requirement is that the mechanical integrity of the fuel rod should be maintained by the spacer grid assembly during the operation of the reactor. It was known that fretting damage to the fuel rod can be reduced by adjusting the relative moving displacement between the fuel rod and its support. In this study, we used the finite element method to evaluate the characteristics of a sliding support designed to reduce fretting damage of fuel rods.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.251-260
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• 2003

A three dimensional (3-D) method of analysis is presented for determining the free vibration frequencies and mode shapes of deep, tapered rods and beams with circular cross section. Unlike conventional rod and beam theories, which are mathematically one-dimensional (1-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components u/sup r/, u/sub θ/ and u/sub z/, in the radial, circumferential, and axial directions, respectively, are taken to be sinusoidal in time, periodic in , and algebraic polynomials in the r and z directions. Potential (strain) and kinetic energies of the rods and beams are formulated, the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four-digit exactitude is demonstrated for the first five frequencies of the rods and beams. Novel numerical results are tabulated for nine different tapered rods and beams with linear, quadratic, and cubic variations of radial thickness in the axial direction using the 3D theory. Comparisons are also made with results for linearly tapered beams from 1-D classical Euler-Bernoulli beam theory.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.73-79
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• 2002

Fretting wear test in room temperature air was performed to evaluate the wear mechanism of fuel rod using a fretting wear tester, which has been developed for experimental study. The main focus was to compare the wear behaviors of fuel rod against support springs at different contact geometries (i.e. concave and convex) and slip directions (axial and transverse). The wear on the tube was examined by the surface roughness tester, which measures the volume. The result indicated that with change of contact geometry from 5N of normal load to 0.1mm gap, wear volume of tube Increased in the condition of concave spring, but slowly decreased in convex spring. From the results of SEM observation, wear mechanism of each test condition was also depend on the above contact parameters. The wear mechanism of each test condition in room temperature air is discussed.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.928-929
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• 2011

본 논문에서는 IPMSM(Interior Permanent Magnet Synchronous Motor)의 회전자에 보조 슬롯인 노치(Notch)와 자속 장벽인 베리어(Barrier)를 설치하여 전반적인 구동 특성을 향상 시켰으며, 각 형상에 따른 d, q축 인덕턴스의 변화를 고찰하였다. 인덕턴스의 계산은 IPMSM의 등가회로 및 벡터도를 이용하였으며 계산되어진 인덕턴스로 전류위상각에 따른 토크를 계산하고 FEM(Finite Element Method)결과와 비교하였다.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.76-78
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• 2009

Spoke type 영구자석 전동기는 자속이 집중되어 높은 공극자속밀도를 가지는 이점이 있으나 코깅토크가 비교적 크다는 단점이 있다. 소음 진동의 원인이 되는 코깅 토크를 저감하기 위해 모델1, 모델 2를 통해 회전자의 형상을 변화시키는 일반화 계수를 찾고 이를 모델3에 적용시켜 확인하고자 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.609-616
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• 2001

The vibrational characteristics of nonuniform circular rods have been studied theoretically and experimentally in this paper. The differential equation of torsional motion expressed in terms of the angular displacement has been solved exactly and approximately for a stepped circular rod and for a conically-tapered rod. Solutions of the boundary-value problem have yielded the natural frequencies, mode shapes and forced responses of the rods. The theoretical solutions of forced response have been verified by comparing them with experimental ones.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.23-23
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• 2003

• Proceedings of the Korean Vacuum Society Conference
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• 2007.02a
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• pp.150-150
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• 2007