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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 28, Issue 12 - Dec 2004
Volume 28, Issue 11 - Nov 2004
Volume 28, Issue 10 - Oct 2004
Volume 28, Issue 9 - Sep 2004
Volume 28, Issue 8 - Aug 2004
Volume 28, Issue 7 - Jul 2004
Volume 28, Issue 6 - Jun 2004
Volume 28, Issue 5 - May 2004
Volume 28, Issue 4 - Apr 2004
Volume 28, Issue 3 - Mar 2004
Volume 28, Issue 2 - Feb 2004
Volume 28, Issue 1 - Jan 2004
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Mathematical Validation of Multidisciplinary Design Optimization Based on Independent Subspaces
Shin, Moon-Kyun ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 109~117
DOI : 10.3795/KSME-A.2004.28.2.109
Optimization has been successfully applied to systems with a single discipline. As many disciplines are involved in coupled fashion, MDO (multidisciplinary design optimization) technology has been developed. MDO algorithms are trying to solve the coupled aspects generated from interdisciplinary relationship. In a general MDO algorithms, a large design problem is decomposed into small ones which can be easily solved. Although various methods have been proposed for MDO, the research is still in the early stage. This research proposes a new MDO method which is named as MDOIS (Multidisciplinary Design Optimization Based on Independent Subspaces). Many real engineering problems consist of physically separate components and they can be independently designed. The inter-relationship occurs through coupled physics. MDOIS is developed for such problems. In MDOIS, a large system is decomposed into small subsystems. The coupled aspects are solved via system analysis which solves the coupled physics. The algorithm is mathematically validated by showing that the solution satisfies the Karush-Kuhn-Tucker condition.
Noise Reduction Characteristics of a High-performance Air-gap Resonator
Kang, Sang-Wook ; Lee, Jang-Moo ; Lim, Won-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 118~124
DOI : 10.3795/KSME-A.2004.28.2.118
The objective of the paper is to demonstrate the noise reduction characteristics of an air-gap resonator, which is composed of an air gap and a partition sheet. By means of installing the air-gap resonator in an enclosed cavity, acoustic resonance can be effectively suppressed using a small space. In particular, it is revealed from a simple, one-dimensional model that the air-gap resonator serves as the Helmholtz resonator that generally absorbs acoustic resonance energy at its resonance frequency. As a result, the air-8ap resonator also has a resonance frequency, which can be predicted with a simple frequency equation derived in the paper. Finally, verification experiments show that the air-gap resonator can be effectively designed by predicting a reasonable gap thickness using the simple frequency-equation.
An Image Segmentation Method and Similarity Measurement Using fuzzy Algorithm for Object Recognition
Kim, Dong-Gi ; Lee, Seong-Gyu ; Lee, Moon-Wook ; Kang, E-Sok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 125~132
DOI : 10.3795/KSME-A.2004.28.2.125
In this paper, we propose a new two-stage segmentation method for the effective object recognition which uses region-growing algorithm and k-means clustering method. At first, an image is segmented into many small regions via region growing algorithm. And then the segmented small regions are merged in several regions so that the regions of an object may be included in the same region using typical k-means clustering method. This paper also establishes similarity measurement which is useful for object recognition in an image. Similarity is measured by fuzzy system whose input variables are compactness, magnitude of biasness and orientation of biasness of the object image, which are geometrical features of the object. To verify the effectiveness of the proposed two-stage segmentation method and similarity measurement, experiments for object recognition were made and the results show that they are applicable to object recognition under normal circumstance as well as under abnormal circumstance of being.
An Effective Quasi-static Modeling of the Piezoelectric Benders
Park, Jong-Kyu ; Moon, Won-Kyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 133~142
DOI : 10.3795/KSME-A.2004.28.2.133
In this article, the constitutive relations of three types of piezoelectric benders, which are a unimorph bender, a bimorph bender and a triple-layer bender, are derived based on the beam theory under the quasi-static equilibrium condition. The relation coefficients are described as the geometry and material properties of the benders. More general constitutive relations involving fixed-free, fixed-roll, and fixed-simply supported boundary conditions under the inconsistent length condition between the piezoelectric layer and the nonpiezoelectric one are discussed. The complicated constitutive relations can be easily calculated and checked by using the symbolic function in ‘Mathematica’. The relation coefficients for the benders are plotted in three dimensional graph using the developed program.
Study on the Stability of Elastic Material Subjected to Dry Friction Force
Ko, Jun-Bin ; Jang, Tag-Soon ; Ryu, Si-Ung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 143~148
DOI : 10.3795/KSME-A.2004.28.2.143
This paper discussed on the stability of elastic material subjected to dry friction force for low boundary conditions: clamped free, clamped-simply supported, simply supported-simply supported, clamped-clamped. It is assumed in this paper that the dry frictional force between a tool stand and an elastic material can be modeled as a distributed follower force. The friction material is modeled for simplicity into a Winkler-type elastic foundation. The stability of beams on the elastic foundation subjected to distribute follower force is formulated by using finite element method to have a standard eigenvalue problem. It is found that the clamped-free beam loses its stability in the flutter type instability, the simply supported-simply supported beam loses its stability in the divergence type instability and the other two boundary conditions the beams lose their stability in the divergence-flutter type instability.
A Parametric Study of the Hemming Process by Finite Element Analysis
Kim, Hyung-Jong ; Choi, Won-Mog ; Lim, Jae-Kyu ; Park, Chun-Dal ; Lee, Woo-Hong ; Kim, Heon-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 149~157
DOI : 10.3795/KSME-A.2004.28.2.149
Implicit finite element analysis of the flat surface-straight edge hemming process is performed by using a commercial code ABAQUS/Standard. Methods of finite element modeling for springback simulation and contact pair definition are discussed. An optimal mesh system is chosen through the error analysis that is based on the smoothing of discontinuity in the state variables. This study has focused on the investigation of the influence of process parameters in flanging, pre-hemming and main hemming on final hem quality, which can be defined by turn-down, warp and roll-in. The parameters adopted in this parametric study are flange length, flange angle, flanging die corner radius, face angle and insertion angle of pre-hemming punch, and over-stroke of pre-hemming and main hemming punches.
Experimental and Analytical Study on Burst Pressure of a Steam Generator Tube with a T-type Combination Crack
Shin, Kyu-In ; Park, Jai-Hak ; Kim, Hong-Deok ; Chung, Han-Sub ; Choi, Young-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 158~164
DOI : 10.3795/KSME-A.2004.28.2.158
Steam generator tubes experience widespread degradations such as stress corrosion cracking, wear, tube rupture, denting, fatigue and so on. The resulting damages can cause tube bursting or leak of the primary water which contains radioactivity Therefore the allowable size of the damage is required to be determined on the maintenance purpose. The burst pressure of a tube with a T-type combination crack consisting of longitudinal and circumferential cracks is obtained experimentally and analytically. Fracture parameters such as stress intensity factor and crack opening angle are investigated. Also the burst pressure for a T-type combination crack is compared with that of a single longitudinal crack to develop a length-based criteria.
Butt Welding Characteristics of Austenitic 304 Stainless Steel Using a Continuous Wave Nd:YAG Laser Beam
Yoo, Young-Tae ; Oh, Yong-Seok ; Shin, Ho-Jun ; Im, Kie-Gon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 165~173
DOI : 10.3795/KSME-A.2004.28.2.165
Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much faster than those involved in conventional arc welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameters such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar plates, etc. The following conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/ aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power.
Evaluation of Delamination for Fiber Reinforced Metal Laminates Using a Pseudo Crack Model
Song, Sam-Hong ; Kim, Cheol-Woong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 174~180
DOI : 10.3795/KSME-A.2004.28.2.174
If Fiber Reinforced Metal Laminates(FRMLs) were delaminated, the decrease of stiffness and fiber bridging effect would result in the sudden aggravation of fatigue characteristics. It was reported that the delamination of FRMLs resulted from the crack of metal layers and that it depended on the crack growth. While cracks were made in FRMLs containing a saw-cuts under fatigue loading, cracks could be produced or not in FRMLs with circular holes under the same condition. When the FRMLs with the circular holes produce not the crack but the delamination, it is not possible to analyze it by the conventional fracture parameters expressed as the function of the crack. And so, this research suggests a new analytical model of the delamination to make the comparison of the delamination behavior possible whenever the cracks occur or not. Therefore, a new analytical model called Pseudo Crack Model(PCM) was suggested to compare the delaminations whether cracks were made or not. The relationship between the crack energy consumption rate(
) and the delamination energy consumption rate(
) was discussed and it was also known that the effect of
was larger than that of
Finite Element Analysis of Power Steering Hose Subject to Internal Pressure
Cho, Jin-Rae ; Jeon, Do-Hyung ; Roh, Gi-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 181~188
DOI : 10.3795/KSME-A.2004.28.2.181
The objective of this paper is to numerically examine the mechanical behavior of the swaged power steering(PS) hose subject to internal pressure. PS hose experiences a large internal pressure change in operating, so it`s material part has to resist a cyclic expansion and compression without causing oil leakage. This cyclic pressure is intimately associated with fatigue failure of PS hose. In this study, we compare two types of PS hose. The numerical investigation is composed of three steps; swaging analysis, low and high pressure analyses. The comparative numerical results provide the basic data for the optimal PS design.
Finite Element Analysis of Hydrogen Concentration for Blister Growth Estimation of CANDU Pressure Tube
Huh, Nam-Su ; Kim, Yun-Jae ; Kim, Young-Jin ; Kim, Young-Seok ; Cheong, Yong-Moo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 189~195
DOI : 10.3795/KSME-A.2004.28.2.189
The pressure tubes, which contain high temperature heavy water and fuel, are within the core of a CANDU nuclear reactor, and are thus subjected to high stresses, temperature gradient, and neutron flux. Further, it is well known that pressure tubes of cold-worked Zr-2.5Nb materials result in hydrogen diffusion, which create fully-hydrided regions (frequently called Blister). Thus a proper investigation of hydrogen diffusion within zirconium-alloy nuclear components, such as CANDU pressure tube and fuel channels is essential to predict the structural integrity of these components. In this respect, this paper presents numerical investigation of hydrogen diffusion to quantify the hydrogen concentration fur blister growth of CANDU pressure tube. For this purpose, coupled temperature-hydrogen diffusion analyses are performed by means of two-dimensional finite element analysis. Comparison of predicted temperature field and blister with published test data shows good agreement.
Cutting Characteristics and Deformed Layer of Type 316LN Stainless Steel
Oh, Sun-Sae ; Yi, Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 196~205
DOI : 10.3795/KSME-A.2004.28.2.196
The cutting characteristics and the deformed layer of nitrogen(N)-added type 316LN stainless steel were comparatively investigated to type 316L stainless steel. The cutting force, the surface roughness(Ra) and the tool wear in face milling works were measured with cutting conditions, and the deformed layers were obtained from micro-hardness testing method. The cutting resistance of type 316LN was similar to type 316L in spite of its high strength. The surface roughness of type 316LN was superior to type 316L for all the cutting conditions. In particular, in the high cutting speed above 345m/min, the surface roughness of the two stainless steels was closely same. The deformed layer thickness of the two stainless steels was generated in the 150
ranges, and its value of type 316LN was lower than that of type 316L. This is due to the high strength properties by nitrogen effect. It was found that type 316LN was higher in the tool wear than that type 316L, and flank wear was dominant to crater wear. In face milling works of type 316LN steel, tool wear is regarded as a important problem.
Structural Design of Piezoelectric Microactuator Using Topology Optimization
Chae, Jin-Sic ; Min, Seung-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 2, 2004, Pages 206~213
DOI : 10.3795/KSME-A.2004.28.2.206
In this study, the topology optimization is applied to the design of a piezoelectric microactuator satisfying the specific mean transduction ratio(MTR). The optimization problem is formulated to minimize the difference between the specified and the current mean transduction ratio. In order to analyze the response of the piezoelectric-structure coupled system, both the structural and the electric potential are considered in the finite element method. The optimization problem is resolved by using Sequential Linear Programming(SLP) and the results of test problems show that the design of a piezoelectric microactuator with the specified mean transduction ratio can be obtained.