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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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Robust Observer Design for Multi-Output Systems Using Eigenstructure Assignment
Huh, Kun-Soo ; Nam, Joon-Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1621~1628
DOI : 10.3795/KSME-A.2004.28.11.1621
This paper proposes a design methodology for the robust observer using the eigenstructure assignment in multi-output systems so that the observer is less sensitive to the ill-conditioning factors such as unknown initial estimation error, modeling error and measurement bias in transient and steady-state observer performance. The robustness of the observer can be achieved by selecting the desired eigenvector matrix to have a small condition number that guarantees the small upper bound of the estimation error. So the left singular vectors of the unitary matrix spanned by space of the achievable eigenvectors are selected as a desired eigenvectors. Also, this paper proposes how to select the desired eigenvector based on the measure of observability and designs the observer with small gain. An example of a spindle drive system is simulated to validate the robustness to the ill-conditioning factors in the observer performance.
Solidification Simulation for Optimal Cooling of Bloom Type Continuous Casting Machine
Jung, Young-Jin ; Kim, Young-Mo ; Cho, Kee-Hyeon ; Kang, Chung-Gil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1629~1636
DOI : 10.3795/KSME-A.2004.28.11.1629
The continuous casting is primarily a heat-extraction process in which the heat transfer at various cooling zones profoundly influences quality of products. So development of numerical model is necessarily needed for more specific and clear investigations upon heat transfer mechanism at mold and secondary cooling zones. In this study, heat transfer coefficients which show the characteristic of heat transfer mechanism in mold are calculated for more exact analysis with temperature measured in bloom mold using optimal algorithm, and finally the validity of cooling conditions at secondary cooling zone actually used at field fur 30 Ton bloom type continuous casting of 0.187%C is investigated. From the results of solidification analysis, the characteristic of bloom mold shows a similar tendency with that of previous studies, and optimized cooling conditions for 0.187%C are presented.
Adaptive Image Transmission Scheme for Vision-Based Telerobot Control
Lee, Jong-Kwang ; Yoon, Ji-Sup ; Kang, E-Sok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1637~1645
DOI : 10.3795/KSME-A.2004.28.11.1637
In remote control of telerobotics equipment, the real-time visual feedback is necessary in order to facilitate real-time control. Because of the network congestion and the associated delays, the real-time image feedback is generally difficult in the public networks like internet. If the remote user is not able to receive the image feedback within a certain time, the work performance may tend to decrease, and it makes difficulties to control of the telerobotics equipment. In this paper, we propose an improved visual feedback scheme over the internet for telerobotics system. The size of a remote site image and its quality are adjusted for efficient transmission. The constructed system has a better real-time update characteristics, and shows a potential for the real-time visual control of the telerobotics system.
Submicro-displacement Measuring System with Moire Interferometer and Application to the Themal Deformation of PBGA Package
Oh, Ki-Hwan ; Joo, Jin-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1646~1655
DOI : 10.3795/KSME-A.2004.28.11.1646
A description of the basic principles of moire interferometry leads to the design of a eight-mirror four-beam interferometer for obtaining fringe patterns representing contour-maps of in-Plane displacements. The technique is implemented by the optical system using an environmental chamber for submicro-displacement mesurement. In order to estimate the reliability and applicabili쇼 of the system developed, the measurement of coefficient of thermal expansion (CTE) for a aluminium block is performed. Consequently, the system is applied to the measurement of thermal deformation of a WB-PBGA package assembly. Temperature dependent analyses of global and local deformations are presented to study the effect of the mismatch of CTE between materials composed of the package assemblies. Bending displacements of the packages and average strains of solder balls are documented. Thermal induced displacements calculated by FEM agree quantitatively with experimental results.
Application of Learning Control for U-type Tuned Liquid Damper System
Ga, Chun-Sik ; Ryu, Yeong-Soon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1656~1663
DOI : 10.3795/KSME-A.2004.28.11.1656
As the structures become larger, higher and more complicated, the demand for safety level has increased. In recent years, TLD(Tuned Liquid Damper) proved to be a successful control tool for reducing structural vibrations. For this reason, the influence of some key parameters of the U-type TLD on the dynamic response is studied. And simple and effectively developed learning control logic is used to control vibration of U type Tuned Liquid Damper system. The purpose of this paper is design optimal control system to deal with unknown errors from non linearity and variation that cost modeling difficulty in complex structure and is followed with the desired behavior. Finally this hybrid control method applied to U type Tuned Liquid Damper structure gives the benefit from better performance of precision and stability of the structure by reducing vibration effect. This research leads to safety design in various structure to robust unspecified foreign disturbances such as windy-load and earthquake.
Construction and Measurement of Three-Dimensional Knee Joint Model of Koreans
Park, Ki-Bong ; Kim, Ki-Bum ; Son, Kwon ; Suh, Jeung-Tak ; Moon, Byung-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1664~1671
DOI : 10.3795/KSME-A.2004.28.11.1664
It is necessary to have a model that describes the feature of the knee Joint with a sufficient accuracy. Koreans, however, do not have their own knee joint model to be used in the total knee replacement arthroplasty. They have to use European or American models which do not match Koreans. Three-dimensional visualization techniques are found to be useful in a wide range of medical applications. Three-dimensional imaging studies such as CT(computed tomography) and MRI(magnetic resonance image) provide the primary source of patient-specific data. Three-dimensional knee joint models were constructed by image processing of the CT data of 10 subjects. Using the constructed model, the dimensions of Korean knee joint were measured. And this study proposed a three-dimensional model and data, which can be helpful to develop Korean knee implants and to analyze knee joint movements.
Modeling and Active Control of an Air-Cell Seat for Ride-Comfort Improvement
Hong, Keum-Shik ; Hwang, Su-Hwan ; Hong, Kyung-Tae ; Yoo, Wan-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1672~1684
DOI : 10.3795/KSME-A.2004.28.11.1672
In this paper, an active vibration control with the use of an air-cell seat for passenger cars is investigated. The roles of the air-cell inserted between the polyurethane foam of the seat and seat cover are first to extend the seat's capability to adopt various shapes of human body and to improve the ride-comfort against road disturbances. The air-cell seat is modeled as a 1-d.o.f. spring-damper system. Because an exact modeling of the air-cell itself is alomost impossible, its dynamic characteristics are analyzed through experiments. A road-adaptive gain-scheduled sky-hook control for the air-cell seat system is proposed. The skyhook gains are scheduled in such a way that the acceleration level transmitted to human body on various road conditions is minimized. Simulations and experimental results are provided.
Failsafe Logic for a vehicle Stability Control System
Min, Kyung-Chan ; Lee, Gun-Bok ; Yi, Kyoung-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1685~1691
DOI : 10.3795/KSME-A.2004.28.11.1685
This paper describes the fault detection and failsafe logic to be used in an Electronic Stability Program(ESP). The aim of this paper is to prevent of erroneous controls in the ESP. Developed this paper introduces the fault detection logic and evaluation of residual signals. The failsafe logic consists of four redundant sub-models, which can be used for detecting the faults in various sensors (yaw rate, lateral acceleration, steering wheel angle). We present two mathematical residual generation methods : one is a method using the average value and the other is a method using the minimum value of the each residual. We verified a failsafe logic developed using vehicle test results also we compare vehicle model based simulation results with test vehicle results.
Numerical Study on the Hot Spots of Friction Surface in Disk Brakes
Kim, Chung-Kyun ; Cho, Seung-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1692~1696
DOI : 10.3795/KSME-A.2004.28.11.1692
This paper presents the thermally induced hot spot characteristics of rubbing surface in the friction pad disk brake. During the braking period, the rubbing surface with irregular asperities that are strongly engaged in rough surface, wear, and deformed surface due to a friction heating may produce an irregular distorted geometry of the disk surface. The tribological interactions between the disk and the pads are unstable if the contact stress is severe, in which the irregularity develops the contact pressure distribution, leading eventually to localized contact, high temperature and formation of hot spots. The computed results of contact spots that are simulated using a coupled thermal-mechanical analysis present sinusoidal distortions and localized extrusions of the disk surface, which are strongly related to a hot spot in the practical disk brake.
Design and Calibration of Acousto-Optic Tunable Filter(AOTF) for Near Infrared Spectral Analysis
You, Jang-Woo ; Kim, Dae-Suk ; Kwak, Yoon-Keun ; Kim, Soo-Hyun ; Lee, Yun-Woo ; Hwang, In-Duk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1697~1702
DOI : 10.3795/KSME-A.2004.28.11.1697
In this paper, we proposed the design and calibration method for the near infrared Acousto-Optic Tunable Filter (AOTF). The theory and design principles of AOTF for the visible light are well known since I.C.Chang has developed the parallel tangent condition for the non-collinear AOTF. Deflection angle, frequency-wavelength relation, spectral resolution, etc. were calculated based on the theory of AOTF. From this result, important parameters - incident and acoustic angle - to fabricate AOTF were decided. We measured the spectral resolution and the relation between electrical driving frequency and the Optical wavelength of diffracted light to calibrate the near infrared AOTF. About 40 ∼ 80 MHz electrical frequency was required to get 1200 ∼ 2200 nm near infrared light. Spectral resolution was less than 10 nm in the near infrared region.
Topology Design Optimization of a Magnetic System Consisting of Permanent Magnets and Yokes and its Application to the Bias Magnet System of a Magnetostrictive Sensor
Cho, Seung-Hyun ; Kim, Yoon-Young ; Yoo, Jeong-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1703~1710
DOI : 10.3795/KSME-A.2004.28.11.1703
The objective of this investigation is to formulate and carry out the topology optimization of a magnetic system consisting of permanent magnets and yokes. Earlier investigations on magnetic field topology optimization have been limited on the design optimization of yokes or permanent magnets alone. After giving the motivation for the simultaneous design of permanent magnets and yokes, we develop the topology optimization formulation of the coupled system by extending the technique used in structural problems. In the present development, we will also examine the effects of the functional form for permeability penalization on the optimized topology.
Track System Interactions Between the Track Link and the Ground
Ryu, Han-Sik ; Jang, Jung-Sun ; Choi, Jin-Hwan ; Bae, Dae-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1711~1718
DOI : 10.3795/KSME-A.2004.28.11.1711
When the tracked vehicle is running on various types of terrain, the physical properties of the interacting ground can be different. In this paper, the interactions between track link and soft soil ground are investigated using static sinkage theory of soil ground. Grouser surfaces of a track link and triangular patches of ground are implemented for contact detection algorithm. Contact force at each segment area of a track link is computed respectively by using virtual work concept. Bekker's static soil sinkage model is applied for pressure-sinkage relationship and shear stress-shear displacement relationship proposed by Janosi and Hanamoto is used for tangential shear forces. The repetitive normal loads of a terrain are considered because a terrain element is subject to the repetitive loading of the roadwheels of a tracked vehicle. The methods how to apply Bekker's soil theory for multibody track system are proposed in this investigation and demonstrated numerically by high mobility tracked vehicle.
Lead-Lag Controller Design of Direct Drive Servo Valve Using Complex Method
Lee, Seong-Rae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1719~1726
DOI : 10.3795/KSME-A.2004.28.11.1719
Direct drive servovalve(DDV) is a kind of one-stage valve because the main spool valve is directly driven by the DC motor. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the lead-lag controller is designed using the complex method that is one kind of constrained direct search method.
Absorptance and Electrical Properties Evaluation of Nickel Layer Deposited onto Thin Film Pyroelectric PZT IR Detector
Ko, Jong-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1727~1732
DOI : 10.3795/KSME-A.2004.28.11.1727
A nickel layer was deposited onto the PZT thin films, serving both as a selective radiation absorption layer and as a top electrode. The absorption properties of such nickel coated multi-layered infrared detectors were studied in the visible and infrared wavelength ranges. The optimal thickness of the nickel layer on our substrate was 10nm. The maximum absorption coefficient of the deposited 10nm thick nickel layer was 0.7 at a 632nm wavelength. However, a striking asymmetric polarization hysteresis loop was observed in these PZT thin films with nickel as the top electrode. This asymmetric polarization was attributed to the difference between the dynamic pyroelectric responses in these Ni/PZT/Pt films poled either positively or negatively before the measurement. A positively poled film showed a 40% higher voltage response than a negatively poled detector.
Decoupling Control of Levitation and Thrust Motion of The Transverse Flux Linear Induction Motor Using DC-biased Multi Phase Inputs
Jung, Kwang-Suk ; Huh, Jin-Hyuk ; Baek, Yoon-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1733~1740
DOI : 10.3795/KSME-A.2004.28.11.1733
In the transverse flux linear induction motor(TFLIM) with the general secondary composed of conductor and back-yoke, there exists a magnetized force into the normal direction or the air-gap direction of the thrust motion as well as the thrust force. Therefore, the various methodologies have been tried to use the normal force by the two independent control variables of the multi-phase input. But, as the force depends inevitably and strongly on the thrust force, it is essential to decouple both forces for two control index. In this paper, we suggest a novel approach capable of compensating the couple between both forces and the control index by using the DC-biased multi-phase input, and then realizing the independent control of TFLIM.
Assessment of Steam Generator Tubes with Multiple Axial Through-Wall Cracks
Moon, Seong-In ; Chang, Yoon-Suk ; Kim, Young-Jin ; Lee, Jin-Ho ; Song, Myung-Ho ; Choi, Young-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1741~1751
DOI : 10.3795/KSME-A.2004.28.11.1741
It is commonly requested that the steam generator tubes wall-thinned in excess of 40% should be plugged. However, the plugging criterion is known to be too conservative for some locations and types of defects and its application is limited to a single crack in spite of the fact that the occurrence of multiple through-wall cracks is more common in general. The objective of this research is to propose the optimum failure prediction models for two adjacent through-wall cracks in steam generator tubes. The conservatism of the present plugging criteria was reviewed using the existing failure prediction models for a single crack, and six new failure prediction models for multiple through-wall cracks have been introduced. Then, in order to determine the optimum ones among these new local or global failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two adjacent through-wall cracks in thin plate were carried out. Thereby, the reaction force model, plastic zone contact model and COD (Crack-Opening Displacement) base model were selected as the optimum ones for assessment of steam generator tubes with multiple through-wall cracks. The selected optimum failure prediction models, finally, were used to estimate the coalescence pressure of two adjacent through-wall cracks in steam generator tubes.
Derivation of Effective Material Properties of Reinforced Braid Layer Using Detailed 3-D Finite Element Model
Song, Jeong-In ; Cho, Jin-Rae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1752~1759
DOI : 10.3795/KSME-A.2004.28.11.1752
Reinforced braid layer (RBL) in automobile power steering hose plays an important role in power steering system. When the working oil is applied to the power steering hose, RBL suppresses rubber hose deformation from internal pressure and heat expansion. RBL is woven textile composites having a double-row structure of nylon cords twisted with the specific helix angle. In this paper, effective material properties of RBL are estimated using a detailed 3-D finite element model considering its complicated geometry. Numerical experiments based on a superposition method are carried out to simulate uniaxial tensile loading condition.
Sensitivity Approach of Sequential Sampling for Kriging Model
Lee, Tae-Hee ; Jung, Jae-Jun ; Hwang, In-Kyo ; Lee, Chang-Seob ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1760~1767
DOI : 10.3795/KSME-A.2004.28.11.1760
Sequential sampling approaches of a metamodel that sampling points are updated sequentially become a significant consideration in metamodeling technique. Sequential sampling design is more effective than classical space filling design of all-at-once sampling because sequential sampling design is to add new sampling points by means of distance between sampling points or precdiction error obtained from metamodel. However, though the extremum points can strongly reflect the behaviors of responses, the existing sequential sampling designs are inefficient to approximate extremum points of original model. In this research, new sequential sampling approach using the sensitivity of Kriging model is proposed, so that new approach reflects the behaviors of response sequentially. Various sequential sampling designs are reviewed and the performances of the proposed approach are compared with those of existing sequential sampling approaches by using mean squared error. The accuracy of the proposed approach is investigated against optimization results of test problems so that superiority of the sensitivity approach is verified.
A Study on the Collapse Modes and Energy Absorption Characteristics of AI/CFRP Compound Tubes Under Axial Compression
Cha, Cheon-Seok ; Lee, Kil-Sung ; Chung, Jin-Oh ; Yang, In-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1768~1775
DOI : 10.3795/KSME-A.2004.28.11.1768
The compressive axial collapse tests were performed to investigate collapse modes and energy absorption characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP(Carbon Fiber Reinforced Plastics) outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different CFRP orientation angles. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, specific energy absorption were the highest for Al/CFRP, CFRP in the middle, and aluminum the lowest. Also, specific energy absorption of circular tubes was higher than square tubes'. It turned out that CFRP orientation angle of Al/CFRP compound tubes influence specific energy absorption together with the collapse modes of the tubes.
A Study on the Bimaterial Constant of Two Dissimillar Isotropic Bimaterial Under Static and Dynamic Load
Shin, Dong-Chul ; Hawong, Jai-Sug ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1776~1785
DOI : 10.3795/KSME-A.2004.28.11.1776
In this research, the relationships between static bimaterial constant and dynamic oscillation index are studied. It was certified that static bimaterial constant has the same form equation as the dynamic oscillation index. Bimaterial constant and oscillation index are increased with the increment of Young's modulus ratio and approached to the some value. Isochromatic fringe patterns are slanted to the left side with increment of bimaterial constants and oscillation index. Though patterns of stress components in above the crack surface are similar to each other, their magnitudes are different a little. In the ahead of crack tip, there are big differences in the isochromatic fringe patterns and their magnitudes. The influence of bimaterial with Young's modulus ratio is bigger in the propagation crack than in the stationary crack.
Evaluation of Landing Impact Force of Court Sport Shoes by Finite Element Method
Kim, Seong-Ho ; Ryu, Sung-Heon ; Choi, Joo-Hyung ; Cho, Jin-Rae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1786~1793
DOI : 10.3795/KSME-A.2004.28.11.1786
A fundamental function of court sport shoes was considered as the protection of human feet from unexpected injuries. But, recently its role for improving the playing competency has been regarded as of more importance. In connection of this situation, intensive efforts are world-widely forced on the development of court sport shoes proving the excellent playing competency by taking kinesiology and biomechanics into consideration. However, the success of this goal depends definitely on the shoes design based upon the reliable evaluation of shoes functional parts. This paper addresses the application of finite element method to the evaluation of landing impact force of court sport shoes. In order to reflect the coupling effect between leg and shoes accurately and effectively, we construct a fully coupled shoes-leg FEM model which does not rely on the independent experimental data any more. Through the numerical experiments, we assess the reliability of the coupled FEM model by comparing with the experimental results and investigate the landing impact characteristics of court sport shoes.
Fabrication of High Aspect Ratio 100nm-Scale Nickel Stamper Using E-Beam Writing based on Chrome/Quartz Mask Without Anti-Reflection Layer for Injection Molding of Optical Grating Patterns
Seo, Young-Ho ; Choi, Doo-Sun ; Lee, Joon-Hyoung ; Je, Tae-Jin ; Whang, Kyung-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1794~1798
DOI : 10.3795/KSME-A.2004.28.11.1794
We present a fabrication method of high aspect ratio 100nm-scale nickel stamper using e-beam writing for the injection molding of optical grating patterns. Conventional nickel stamper is fabricated by nickel electroplating process which is followed by seed layer deposition. In this paper, we have used chrome coated blank mask without anti-reflection layer of CrON in order to simplified electroplating process. In experimental study, we have optimized electron-beam dosage for 100nm-scale optical grating patterns with 2.5-aspect ratio, and fabricated nickel stamper using above grating patterns as PR mold. Fabricated nickel stamper have showed height of 240
20nm and width of 116
A Study on the Crack Propagation Criterion of Orthotropic Material by the Static Photoelastic Experimental Hybrid Method
Shin, Dong-Chul ; Hawong, Jai-Sug ; Nam, Sung-Su ; Kwon, O-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1799~1806
DOI : 10.3795/KSME-A.2004.28.11.1799
The static photoelastic experiment was applied to orthotropic materials. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic experimental hybrid method for orthotropic material was introduced and its validity had been assured. Crack propagation criterion used the stress components, which are considered the higher order terms, obtained from the static photoelastic experimental hybrid method was introduced and it was applied to the minimum strain energy density criterion, the maximum tangential stress criterion and mode mixity. Comparing the actual initial angle of crack propagation with the theoretical initial angle of crack propagation obtained from the above failure criterions, the validities of the above two criterions are assured and the optimal distance (
) from the crack-tip is 0.01mm in order to get the initial angle of crack propagation of orthotropic material(C.F.E.C.).
Effects of Friction Energy on Polishing Results in CMP Process
Lee, Hyun-Seop ; Park, Boum-Young ; Kim, Goo-Youn ; Kim, Hyoung-Jae ; Seo, Heon-Deok ; Jeong, Hae-Do ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1807~1812
DOI : 10.3795/KSME-A.2004.28.11.1807
The application of chemical mechanical polishing(CMP) has a long history. Recently, CMP has been used in the planarization of the interlayer dielectric(ILD) and metal used to form the multilevel interconnections between each layers. Therefore, much research has been conducted to understand the basic mechanism of the CMP process. CMP performed by the down force and the relative speed between pad and wafer with slurry is typical tribo-system. In general, studies have indicated that removal rate is relative to energy. Accordingly, in this study, CMP results will be analyzed by a viewpoint of the friction energy using friction force measurement. The results show that energy would not constant in the same removal rate conditions
Evaluation of Plastic Collapse Behavior for Multiple Cracked Structures
Moon, Seong-In ; Chang, Yoon-Suk ; Kim, Young-Jin ; Lee, Jin-Ho ; Song, Myung-Ho ; Choi, Young-Hwan ; Hwang, Seong-Sik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 28, issue 11, 2004, Pages 1813~1821
DOI : 10.3795/KSME-A.2004.28.11.1813
Until now, the 40% of wall thickness criterion, which is generally used for the plugging of steam generator tubes, has been applied only to a single cracked geometry. In the previous study by the authors, a total number of 9 local failure prediction models were introduced to estimate the coalescence load of two collinear through-wall cracks and, then, the reaction force model and plastic zone contact model were selected as the optimum ones. The objective of this study is to estimate the coalescence load of two collinear through-wall cracks in steam generator tube by using the optimum local failure prediction models. In order to investigate the applicability of the optimum local failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two collinear through-wall cracks in steam generator tube were carried out. Thereby, the applicability of the optimum local failure prediction models was verified and, finally, a coalescence evaluation diagram which can be used to determine whether the adjacent cracks detected by NDE coalesce or not has been developed.