32 results on '"Koung-Suk Kim"'
Search Results
2. Evaluation of Residual Stress on Pipe Welded Joints Using Laser Interferometry
- Author
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Koung Suk Kim, Man Gyun Na, and Ho Seob Chang
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Materials science ,business.industry ,Young's modulus ,Structural engineering ,Welding ,Compression (physics) ,law.invention ,symbols.namesake ,law ,Residual stress ,symbols ,Deformation (engineering) ,Composite material ,business ,Base metal ,Elastic modulus ,Tensile testing - Abstract
Residual stresses that occur during the welding process, are the main cause of failure and defects in welded structures. This paper, presents the use of an electronic processing laser speckle interferometer to measure the residual stress of a welded pipe for a nuclear power plant. A tensile testing machine was used to evaluate a welded pipe that failed in compression. The inform plane deformation and modulus of elasticity of the base metal and welds were measured using an interferometer. Varying the load on the welded pipe had a larger effect on the deformation of the base metal the other properties of the base metal and welds. The elastic moduli of the base metal and weld of the welded pipe were 202.46 and 212.14 GPa, respectively, the residual stress was measured to be 6.29 MPa. more...
- Published
- 2014
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3. Quantitative determination of a subsurface defect of reference specimen by lock-in infrared thermography
- Author
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Kisoo Kang, Koung-Suk Kim, Man-Yong Choi, Wontae Kim, and Jeong-Hak Park
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Shearing (physics) ,Materials science ,Pixel ,Infrared ,business.industry ,Mechanical Engineering ,Subtraction ,Condensed Matter Physics ,Quantitative determination ,Metrology ,Optics ,Thermography ,General Materials Science ,Defect size ,business - Abstract
This paper describes the quantitative determination of the sizes and locations of subsurface defects using lock-in infrared thermography. A phase (or temperature) difference between the defect area and the healthy area indicates the qualitative location and size of the defect. To accurately estimate these parameters, the shearing-phase technique has been employed, where the inspected image is shifted by a certain number of pixels to obtain a shifted image while subtraction of one image from the other gives the shearing-phase distribution. The shearing-phase distribution has maximum, minimum, and zero points that help determine quantitatively the size and location of the subsurface defect. Experimental results for a steel plate with artificial subsurface defects show good agreement with actual values. more...
- Published
- 2008
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4. Evaluation of elastic modulus of cantilever beam by TA-ESPI
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Hang-Seo Lee, Ki-Soo Kang, and Koung-Suk Kim
- Subjects
Cantilever ,Materials science ,business.industry ,Acoustics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Vibration ,Speckle pattern ,Interferometry ,Optics ,Normal mode ,Electronic speckle pattern interferometry ,Speckle imaging ,Electrical and Electronic Engineering ,business ,Elastic modulus - Abstract
The paper proposes an evaluation technique for the elastic modulus of a cantilever beam by vibration analysis based on time average electronic speckle pattern interferometry (TA-ESPI) and Euler–Bernoulli equation. General approaches for the measurement of elastic modulus of a thin film are the Nano indentation test, Buldge test, Micro-tensile test, and so on. They each have strength and weakness in the preparation of the test specimen and the analysis of experimental results. ESPI is a type of laser speckle interferometry technique offering non-contact, high-resolution and whole-field measurement. The technique is a common measurement method for vibration mode visualization and surface displacement. Whole-field vibration mode shape (surface displacement distribution) at resonance frequency can be visualized by ESPI. And the maximum surface displacement distribution from ESPI can be used to find the resonance frequency for each vibration mode shape. And the elastic modules of a test material can be easily estimated from the measured resonance frequency and Euler–Bernoulli equation. The TA-ESPI vibration analysis technique can be used to find the elastic modulus of a material requiring simple preparation process and analysis. more...
- Published
- 2007
- Full Text
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5. Influence of Shearing Amount on Detecting Crack-Shaped Internal Defect by Shearography
- Author
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Heo Sub Jang, Ki Soo Kang, Hyun-Chul Jung, and Koung Suk Kim
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Shearing (physics) ,Engineering drawing ,Materials science ,business.industry ,Mechanical Engineering ,Acoustics ,Quantitative determination ,Longitudinal direction ,Vibration ,Shearography ,Mechanics of Materials ,Nondestructive testing ,General Materials Science ,Speckle imaging ,Defect size ,business - Abstract
Shearography, a type of speckle interferometry, is a powerful tool for nondestructive testing (NDT) because it is insensitive to environmental vibration disturbance and easy to detect strain concentration in an internal defect with noncontact and whole field. The shearing amount in Shearography has influence on determining defect size and source location. Thus the shearing amount must be optimally adjusted to get accurate evaluation. This paper investigates the defect size and source location according to the change of shearing amount in artificial slender defects along longitudinal direction of pipeline. Based on the investigation, a new technique is proposed for the quantitative determination of defect size and source location. more...
- Published
- 2006
- Full Text
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6. Quantitative Vibration Amplitude Measurement Using Stroboscopic Phase Shifting ESPI
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Koung Suk Kim and Hyun-Chul Jung
- Subjects
Engineering ,business.industry ,Mechanical Engineering ,Acoustics ,Measure (physics) ,Vibration amplitude ,Deformation (meteorology) ,Stroboscope ,Square (algebra) ,law.invention ,Vibration ,Optics ,Mechanics of Materials ,Normal mode ,law ,Acousto-optic modulator ,General Materials Science ,business - Abstract
The stroboscopic phase shifting ESPI (SPS-ESPI), one of the optical vibration amplitude measurement techniques, is presented. Although the general PS-ESPI can be used for quantitative deformation measurement of the object, this technique cannot measure the vibration amplitude with itself only. The phase change due to the vibration of the object cannot be calculated with general PS-ESPI correctly. Therefore, in order to solve this problem, the stroboscopic illumination must be introduced to the general PS-ESPI. This can be done by using a device called as AOM (Acousto-Optic Modulator). In this paper, SPS-ESPI is applied to measure the vibration amplitude of the square plate whose all edges were fixed. The natural frequencies and mode shapes are analyzed by using ANSYS. And the results obtained by using SPS-ESPI technique are compared with that of the ANSYS analysis. The vibration amplitude is measured by using SPS-ESPI quantitatively. more...
- Published
- 2006
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7. Penetration Fracture Characteristics of CFRP Curved Laminates
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Koung Suk Kim, In Young Yang, Kil Sung Lee, Young Nam Kim, Kwang Hee Im, and Young Jea Cho
- Subjects
Materials science ,Structural material ,business.industry ,Mechanical Engineering ,Composite number ,Stiffness ,Structural engineering ,Penetration (firestop) ,Kinetic energy ,Curvature ,Mechanics of Materials ,Ball (bearing) ,Hardening (metallurgy) ,medicine ,General Materials Science ,Composite material ,medicine.symptom ,business - Abstract
CFRP composite materials widely used as structural materials for airplanes, ships and aero space vehicles because of their high strength and stiffness. This study aims to investigate the effects of curvature and stacking sequence on the penetration characteristics of CFRP laminated shell. They are stacked to [02/902]S, [03/903]S and [02/903/0]S, [0/902/0]S, and their interlaminar numbers are two and four. We are manufactured to composite laminated shells with curvature radii of 100, 150, 200mm and ∞ (flat-plate), respectively. They were cure to the appropriate hardening temperature (130°C) at the vacuum bag of an autoclave. Composite laminated shells of dimensions 100㎜×140㎜ were prepared. The velocity of the steel ball that transversely impacts a specimen was measured both before and after impact by determining the time for the ball to pass two ballistic-screen sensors located at a known distance apart. In general, the kinetic energy after impact-kinetic energy before impact increased in all specimens. Absorbed energy increased as the curvature increased [03/903]S and [02/902]S which is small interlaminar number, was higher than four interlaminar specimen. more...
- Published
- 2005
- Full Text
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8. Non-destructive evaluation of semiconductor package by electronic speckle pattern interferometry
- Author
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Seung-Tack Jung, Ki-Soo Kang, and Koung-Suk Kim
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Semiconductor package ,Chip ,Adhesion strength ,Interferometry ,Optics ,Semiconductor ,Mechanics of Materials ,Electronic speckle pattern interferometry ,Nondestructive testing ,Thermal ,business - Abstract
This paper proposes non-destructive ESPI technique to evaluate inside defects of semiconductor package quantitatively inspection system consists of ESPI system, thermal loading system and adrabatic chamber. The technique has high feasibility in non-destructive testing of semiconductor and gives solutions to the drawbacks in previous technique, time-consuming and the difficulty of quantitative evaluation in result, most of defects are classified in delamination, from which it is inferred to the insufficiency of adhesive strength between layers and nonhomogeneous heat spread The 90% of tested samples have a delamination defect started at the around of the chip which may be related to heat spread design. more...
- Published
- 2005
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9. Non-Destructive evaluation of separation and void defect of a pneumatic tire by speckle shearing interferometry
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Ki-Soo Kang, Nak Yong Ko, Koung-Suk Kim, and Hyun-Chul Jung
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Shearing (physics) ,Void (astronomy) ,Engineering ,business.industry ,Mechanical Engineering ,Acoustics ,Structural engineering ,Speckle pattern ,Interferometry ,Quantitative Result ,Non destructive ,Tread ,business ,Effective factor - Abstract
This paper describes the speckle shearing interferometry, a non-destructive optical method, for quantitative estimation of void defect and monitoring separation defect inside of a pneumatic tire. Previous shearing interferometry has not supplied quantitative result of inside defect, due to effective factors. In the study, factors related to the details of an inside defect are classified and optimized with pipeline simulator. The size and the shape of defect can be estimated accurately to find a critical point and also is closely related with shearing direction. The technique is applied for quantitative estimation of defects inside of a pneumatic tire. The actual traveling tire is monitored to reveal the cause of separation and the starting points. And also unknown void defects on tread are inspected and the size and shape of defects are estimated which has good agreement with the result of visual inspection. more...
- Published
- 2004
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10. Detection of Real Defects in Composite Structures by Laser Techniques
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Young June Kang, Seong Kyun Cheong, Koung Suk Kim, and Young Bae Kim
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Materials science ,Shearography ,Mechanics of Materials ,law ,Mechanical Engineering ,Delamination ,Composite number ,Honeycomb ,General Materials Science ,Composite material ,Laser ,law.invention - Published
- 2004
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11. Quantitative Evaluation of Defect inside Tire by Shearography
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Seong Kyun Cheong, Ki Soo Kang, Sung Mo Yang, Koung Suk Kim, and In Young Yang
- Subjects
Materials science ,Shearography ,Mechanics of Materials ,business.industry ,Mechanical Engineering ,Mechanical engineering ,General Materials Science ,Structural engineering ,business - Published
- 2004
- Full Text
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12. Local collision avoidance of multiple robots using avoidability measure and relative distance
- Author
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Nak Yong Ko, Koung Suk Kim, and Dong Jin Seo
- Subjects
Engineering ,business.industry ,Mechanical Engineering ,Work (physics) ,Measure (physics) ,Collision ,Motion (physics) ,Computer Science::Robotics ,Control theory ,Position (vector) ,Robot ,Motion planning ,business ,Collision avoidance ,Simulation - Abstract
This paper presents a new method driving multiple robots to their goal position without collision. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of how easily a robot can avoid other robots considering the velocity of the robots. To implement the concept to avoid collision among multiple robots, relative distance between the robots is proposed. The relative distance is a virtual distance between robots indicating the threat of collision between the robots. Based on the relative distance, the method calculates repulsive force against a robot from the other robots. Also, attractive force toward the goal position is calculated in terms of the relative distance. These repulsive force and attractive force are added to form the driving force for robot motion. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. In contrast, since the usual potential field method initiates avoidance motion later than the proposed method, it sometimes fails preventing collision or causes hasty motion to avoid other robots. The proposed method works as a local collision-free motion coordination method in conjunction with higher level of task planning and path planning method for multiple robots to do a collaborative job. more...
- Published
- 2004
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13. A lane based obstacle avoidance method for mobile robot navigation
- Author
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Reid Simmons, Koung Suk Kim, and Nak Yong Ko
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Heading (navigation) ,business.industry ,Computer science ,Mechanical Engineering ,Constraint (computer-aided design) ,Work (physics) ,Mobile robot ,Mobile robot navigation ,Motion (physics) ,Robot control ,Obstacle avoidance ,Computer vision ,Artificial intelligence ,business ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
This paper presents a new local obstacle avoidance method for indoor mobile robots. The method uses a new directional approach called the Lane Method. The Lane Method is combined with a velocity space method i.e., the Curvature-Velocity Method to form the Lane-Curvature Method(LCM). The Lane Method divides the work area into lanes, and then chooses the best lane to follow to optimize travel along a desired goal heading. A local heading is then calculated for entering and following the best lane, and CVM uses this local heading to determine the optimal translational and rotational velocities, considering some physical limitations and environmental constraint. By combining both the directional and velocity space methods, LCM yields safe collision-free motion as well as smooth motion taking the physical limitations of the robot motion into account. more...
- Published
- 2003
- Full Text
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14. Measurement of shock waves using phase shifting pulsed holographic interferometer
- Author
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Weon-Jae Ryu, Young-June Kang, Sung-Hoon Baik, and Koung-Suk Kim
- Subjects
Shock wave ,Physics ,business.industry ,Ruby laser ,Phase (waves) ,Holography ,Physics::Optics ,Holographic interferometry ,Interference (wave propagation) ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,law ,Transient (oscillation) ,Electrical and Electronic Engineering ,business ,Beam (structure) - Abstract
A phase shifting pulsed holographic interferometer was applied to the experimental study of the propagation of laser-induced shock waves over metal plates. A double-pulsed ruby laser was used to generate the shock waves and to make a holographic interferogram of the wave fields. The phase shifting method with a dual-reference beam solved the sign ambiguity problem in holographic fringe patterns and allowed a quantitative evaluation of the phase of the interference patterns. The transient surface profile and propagation behavior of the shock wave over plates were investigated from the holographic fringe patterns. more...
- Published
- 2003
- Full Text
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15. Composition and temperature dependence of optical energy gaps of TlGa1−xSbxS2 single crystals
- Author
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Koung-Suk Kim, Sung-Hyu Choe, Ho-Jun Song, Jae-Yeol Kim, and Moon-Seog Jin
- Subjects
Materials science ,Mechanics of Materials ,Mechanical Engineering ,Analytical chemistry ,General Materials Science ,Composition (combinatorics) ,Atomic physics ,Condensed Matter Physics ,Optical energy ,Energy (signal processing) - Abstract
TlGa1−xSbxS2 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) single crystals were grown using the Bridgman–Stockbarger method. The direct energy gaps of the single crystals were found to be 2.586, 2.459, 2.344, 2.228, 2.119, and 1.987 eV for the composition x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0, respectively, at 20 K. The indirect energy gaps were found to be 2.479, 2.357, 2.232, 2.118, 1.983, and 1.871 eV for the composition x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0, respectively, at 20 K. The optical energy gaps decreased linearly with increasing composition x. The temperature dependence of the optical energy gaps for each of the single crystals was well fitted with the Varshni equation. more...
- Published
- 2003
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16. The electronic laser interferometry and laser heating method for residual stress determination
- Author
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Koung-Suk Kim, Weon-Jae Ryu, Young-June Kang, and Kyung-Wan Rho
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Numerical analysis ,Laser ,Finite element method ,law.invention ,Interferometry ,Optics ,law ,Residual stress ,Laser cooling ,Electronics ,business ,Plane stress - Abstract
Residual stress is one of the causes which makes defects in engineering components and materials. These residual stresses can occur in many engineering structures and can sometimes lead to premature failures. There are commonly used methods by which residual stresses are currently measured. But these methods have a little damage and other problems; therefore, a new experimental technique has been devised to measure residual stress in materials with a combination of electronic laser interferometry, laser heating and finite element method. The electronic laser interferometer measures in-plane deformations while the laser heating and cooling provides for very localized stress relief. FEM is used for determining the heat temperature and other parameters. The residual stresses are determined by the amount of strain that is measured subsequent to the heat-up and cool-down of the region being interrogated. A simple model is presented to provide a description of the method. In this paper, the ambiguity problem for the fringe patterns has solved by a phase shifting method. more...
- Published
- 2000
- Full Text
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17. Thermal strain analysis of composite materials by electronic speckle pattern interferometry
- Author
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Hyun-Chul Jung, Young Jun Kang, Sung Pil Yang, Ki Soo Kang, Myung Seak Hong, Wan Shik Jang, and Koung Suk Kim
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Numerical analysis ,Composite number ,Thermal strain ,Thermal expansion ,Optics ,Surface metrology ,Electronic speckle pattern interferometry ,Fiber ,Composite material ,business ,Thermal analysis - Abstract
This study discusses a non-contact optical technique (electronic speckle pattern interferometry) that is well suited for thermal deformation measurement without any surface preparation and compensating process. Fiber reinforced plastics ([0]16, [0/90]8S) were analyzed by ESPI to determine their thermal expansion coefficients. The thermal expansion coefficient of the transverse direction of a uniaxial composite is evaluated as 48.78×10−6(1/°C). Also, the thermal expansion coefficient of the cross-ply laminate [0/90]8S is numerically estimated as 3.23×10−6 (1/°C) that is compared with that measured by ESPI. more...
- Published
- 2000
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18. Experimental analysis of vibration modes of plates using ESPI
- Author
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Woon Gwan Jung, Ki Soo Kang, Yong Hoon Cha, Koung Suk Kim, Hyun-Chul Jung, and Young June Kang
- Subjects
Vibration ,Engineering ,business.industry ,Normal mode ,Mechanical Engineering ,Nondestructive testing ,Electronic speckle pattern interferometry ,Structural engineering ,business ,Excitation ,Finite element method - Abstract
In the world, there are several types of vibration, and these vibrations especially affect the mechanical industry. In this paper, experimental analysis of vibration modes of plates is discussed. Electronic speckle pattern interferometry (ESPI) is one of the optical nondestructive testing techniques. By using the ESPI, vibration modes of plates with various excitation points, ratio of longitudinal and lateral length, and materials are measured and qualitatively compared with the results of theoretical analysis proposed by Warburton. Finally, these vibration modes are quantitatively compared with the result of FEM analysis. The results of this study are as follows: (1) By comparing the theoretical and experimental frequencies, we confirmed qualitatively that deviations of frequencies are within 10% in accuracy. (2) By comparing the experimental vibration mode shapes with the numerical ones of the FEM analysis, we can conclude quantitatively that measuring vibration modes by using the ESPI has high accuracy. more...
- Published
- 1999
- Full Text
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19. In-plane strains measurement by using the electronic speckle pattern interferometry
- Author
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Soon Suck Jang, Ki Soo Kang, Hyun-Chul Jung, Koung Suk Kim, Jong Kook Lee, and Chung Ki Hong
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Analyser ,Astrophysics::Instrumentation and Methods for Astrophysics ,Image processing ,Dual beam ,Interferometry ,Speckle pattern ,In plane ,Optics ,Electronic speckle pattern interferometry ,business ,Strain gauge - Abstract
Two-dimensional in-plane displacements and strains are measured using an electronic speckle pattern interferometry (ESPI) system based on the dual beam speckle interferometric method. Different types of specimens are used: a flat plate, a cracked-plate, and plate with a central hole of 12 mm diameter. Two-dimensional fringes obtained from real-time images are analyzed by an image analyser. The values of in-plane strains obtained by the ESPI technique show high accuracy compared with those measured by strain gages. more...
- Published
- 1998
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20. Measurements of Two-Dimensional Strain Distribution Using the Electronic Speckle Pattern Interferometry
- Author
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Koung-Suk Kim and Masahiko Murozono
- Subjects
Materials science ,Strain (chemistry) ,business.industry ,Mechanical Engineering ,Measure (physics) ,Moiré pattern ,Load cell ,Displacement (vector) ,Optics ,Mechanics of Materials ,Electronic speckle pattern interferometry ,General Materials Science ,business ,Strain gauge ,Tensile testing - Abstract
Electronic speckle pattern interferometry (ESPI) is a very useful method for measuring in-plane surface displacement. Using the cw-laser and image-processing system, it is possible to measure displacement and strain. Unlike traditional strain gauges or the moire method, the ESPI method requires no special surface preparation or attachments and can measure in-plane displacement with no contact and in real time. In this experiment, a specimen was loaded in parallel with a load cell, which provided loading step. The specimen was a flat plate or a plate with a 12 mm-diameter hole in its center. Strain gauges were attached to the specimen in x and y directions. This study provides an example of how ESPI has been used to measure two-dimensional displacement and strain distribution in this specimen. The results measured by ESPI are comparable with the data which were obtained by the strain-gauge method in tensile testing in the 1-ton range more...
- Published
- 1994
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21. Stress Distribution Measurement of Welding Part by Electronic Speckle Pattern Interferometry
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Koung-Suk Kim, Sang-Kyu Baek, Hyum-Chul Jung, Ho-Sub Chang, and Kisoo Kang
- Subjects
Speckle pattern ,Materials science ,law ,Residual stress ,Reference beam ,Electronic speckle pattern interferometry ,Ultimate tensile strength ,Welding ,Composite material ,Porosity ,Joint (geology) ,law.invention - Abstract
The welding which is one of material joining methods plays an important role for development of the modern industry. The welding has several advantages such as high joint effect, high airtightness, and reduction of the materials being used. Nowadays, the applying or loading condition of the plates which are used for various mechanical structures becomes various. For applying the plates to the industrial field, its characteristics by tensile or compressive testing should be measured. Especially, the stress distribution at the welding part must be measured. During welding process, the thermal damage causes several types of defect including porosity, crack, insertion of impurities. A crack at the welding part results from these defects so that the mechanical structures could be destructive. In this paper, the butt welded S30400(STS304 in KS) specimen is prepared and the stress distribution at the welding part is measured by electronic speckle pattern interferometry (ESPI). more...
- Published
- 2007
- Full Text
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22. Quantitative Vibration Amplitude Measurement Using Stroboscopic Phase Shifting ESPI
- Author
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Hyun Chul Jung and Koung Suk Kim
- Published
- 2006
- Full Text
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23. Influence of Shearing Amount on Detecting Crack-Shaped Internal Defect by Shearography
- Author
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Ki Soo Kang, Koung Suk Kim, Hyun Chul Jung, and Heo Sub Jang
- Published
- 2006
- Full Text
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24. Design of decoupled dual servo stage with voice coil motor and linear motor for XY long stroke ultra-precision scanning system
- Author
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Sukwon Lee, Koung-Suk Kim, Dong-Pyo Hong, Ki-Hyun Kim, Moon-Gu Lee, Young-Man Choi, and Dae-Gab Gweon
- Subjects
Magnetic circuit ,Engineering ,Electromagnetic coil ,business.industry ,Control theory ,Linear system ,Voice coil ,Commutation ,Linear motor ,business ,Servo ,Sequential quadratic programming - Abstract
A decoupled dual servo (DDS) stage for ultra-precision scanning system is introduced in this paper. The proposed DDS consists of a 3 axis fine stage for handling and carrying workpieces and a XY coarse stage. Especially, the DDS uses three voice coil motors (VCM) as a planar actuation system of the fine stage to reduce the disturbances due to any mechanical connections with its coarse stage. VCMs are governed by Lorentz law. According to the law and its structure, there are no mechanical connections between coils and magnetic circuits. Moreover, the VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about 5mm2. To break that hurdle, the coarse stage with linear motors is used for the fine stage to move about 200mm2. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. Using MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. For linear motors, Halbach magnet linear motor is proposed and optimally designed in this paper. In addition, for their smooth movements without any frictions, guide systems of the DDS are composed of air bearings. And then, precisely to get their positions, linear scales with 0.1um resolution are used for the coarse's XY motions and plane mirror laser interferometers with 20nm for the fine's XYθz. On scanning, the two stages have same trajectories and are controlled. The control algorithm is Parallel method. The embodied ultra-precision scanning system has about 100nm tracking error and in-positioning stability. more...
- Published
- 2005
- Full Text
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25. Evaluation of elastic modulus of cantilever beam by TA-ESPI
- Author
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M. Y. Choi, Ho-Sub Jang, Ki-Soo Kang, Dong-Pyo Hong, and Koung-Suk Kim
- Subjects
Vibration ,Physics ,Interferometry ,Speckle pattern ,Optics ,Cantilever ,Normal mode ,business.industry ,Electronic speckle pattern interferometry ,Acoustics ,Speckle imaging ,business ,Elastic modulus - Abstract
The paper proposes an evaluation technique for the elastic modulus of a cantilever beam by vibration analysis based on time average electronic speckle pattern interferometry (TA-ESPI) and Euler-Bernoulli equation. General approaches for the measurement of elastic modulus of a thin film are the Nano indentation test, Buldge test, Micro-tensile test, and so on. They each have strength and weakness in the preparation of the test specimen and the analysis of experimental results. ESPI is a type of laser speckle interferometry technique offering non-contact, high-resolution and whole-field measurement. The technique is a common measurement method for vibration mode visualization and surface displacement. Whole-field vibration mode shape (surface displacement distribution) at resonance frequency can be visualized by ESPI. And the maximum surface displacement distribution from ESPI can be used to find the resonance frequency for each vibration mode shape. And the elastic modules of a test material can be easily estimated from the measured resonance frequency and Euler-Bernoulli equation. The TA-ESPI vibration analysis technique can be used to find the elastic modulus of a material requiring simple preparation process and analysis. more...
- Published
- 2005
- Full Text
- View/download PDF
26. Penetration Fracture Characteristics of CFRP Curved Laminates
- Author
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Young Nam Kim, Young Jea Cho, Kil Sung Lee, Kwang Hee Im, Koung Suk Kim, and In Young Yang
- Published
- 2005
- Full Text
- View/download PDF
27. Characterizing the mechanical property of thin film using dynamic ESPI
- Author
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Kisoo Kang, Yong‐Hun Cha, Wan-Shik Jang, and Koung-Suk Kim
- Subjects
Interferometry ,Mechanical property ,Materials science ,chemistry ,Aluminium ,Electronic speckle pattern interferometry ,chemistry.chemical_element ,Speckle imaging ,Thin film ,Composite material ,Elastic modulus ,Characterization (materials science) - Abstract
Speckle interferometry is a powerful technique for the static and dynamic characterization of micromechanical devices. In this paper we emphasize its capabilities for the determination of mechanical properties of Al micro-machined thin films. Micro-tensile testing system and the modified ESPI (Electronic Speckle Pattern Interferometry) for large deformation analysis are developed. Stress-strain curves for aluminum membrane are obtained and the mechanical properties, elastic modulus and yield stress, are estimated. The results show that yield stress is similar to Al bulk material but the elastic modulus is 60% of Al bulk material.Speckle interferometry is a powerful technique for the static and dynamic characterization of micromechanical devices. In this paper we emphasize its capabilities for the determination of mechanical properties of Al micro-machined thin films. Micro-tensile testing system and the modified ESPI (Electronic Speckle Pattern Interferometry) for large deformation analysis are developed. Stress-strain curves for aluminum membrane are obtained and the mechanical properties, elastic modulus and yield stress, are estimated. The results show that yield stress is similar to Al bulk material but the elastic modulus is 60% of Al bulk material. more...
- Published
- 2004
- Full Text
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28. Quantitative Evaluation of a Crack Inside of Pressure Pipeline by Shearography and ESPI
- Author
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Koung-Suk Kim, Dong-Pyo Hong, Kisoo Kang, Man-Yong Choi, and Yong‐Hun Cha
- Subjects
Shearing (physics) ,Interferometry ,Materials science ,Shearography ,business.industry ,Nondestructive testing ,Electronic speckle pattern interferometry ,Crack size ,Structural engineering ,Defect size ,business ,Effective factor - Abstract
Electronic Speckle Pattern Interferometry (ESPI) and Shearography for quantitative analysis of a crack inside of pipelines are described. Shearography is used widely for non‐destructive inspection because of less sensitivity to environmental disturbance and simple interferometer. However, it is difficult to determine the defect size quantitatively because there are so many effect factors‐ shearing distance, shearing direction, and induced load, which depend on operator’s skill and crack information. These effective factors in Shearography are optimized for quantitative analysis and the size of crack is determined. And also, ESPI is used for determination of crack size quantitatively. In ESPI only induced load play an important role and the effective factor is independent on information of a crack. The displacement of object surface is obtained three‐dimensionally and differentiated numerically, which is same to result of Shearography so that crack size can be determined quantitatively without any information of crack. more...
- Published
- 2003
- Full Text
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29. A Study on the Measurement of in-Plane Displacement at High Temperature by Electronic Speckle Pattern Interferometry Method
- Author
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Jae-Yeol Kim, Yong Hoon Cha, Koung-Suk Kim, Hyun-Chul Jung, Seong-Pil Yang, Soon-Suk Jarng, and Hyoung-Tek Kim
- Subjects
Speckle pattern ,Interferometry ,Materials science ,Optics ,Shearography ,business.industry ,Electronic speckle pattern interferometry ,Speckle noise ,Holographic interferometry ,business ,Displacement (vector) ,Thermal expansion - Abstract
In recent years, Laser Speckle Pattern Interferometry(SPI) and its development have enabled surface deformation of structure components and materials to be accurately examined. SPI is a very useful method for measuring in-plane components of displacement. In measuring thermal expansion coefficient, the various problems are occurred, and the measuring limitation is existed. In this study, INCONEL 601 and Tantalum were used as specimen material. Specimens were heated to the high temperature(1000 °C) by electric current. more...
- Published
- 1998
- Full Text
- View/download PDF
30. OS01W0027 Shearography in Tire Industry
- Author
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Changjun Ji, Kisoo Kang, Koung-Suk Kim, Youhwang Lee, Wan-Shik Jang, and Man-Yong Choi
- Subjects
Materials science ,Shearography ,Speckle imaging ,Composite material - Published
- 2003
- Full Text
- View/download PDF
31. Composition and temperature dependence of optical energy gaps of TlGa[sub1-x]Sb[subx]S[sub2] single crystals.
- Author
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Moon-Seog Jin, Jae-Yeol Kim, Koung-Suk Kim, Sung-Hyu Choe, and Ho-Jun Song
- Subjects
CRYSTALS ,BAND gaps ,CONSTITUTION of matter ,PROPERTIES of matter ,MATERIALS - Abstract
Presents a study which investigated the composition and temperature dependence of optical energy gaps of TlGa[sub1-x]Sb[subx]S[sub2] single crystals. Review of related literature; Methodology; Results and discussion. more...
- Published
- 2003
- Full Text
- View/download PDF
32. Stress Distribution Measurement of Welding Part by Electronic Speckle Pattern Interferometry.
- Author
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Gdoutos, E. E., Hyum-Chul Jung, Ho-Sub Chang, Ki-Soo Kang, Sang-Kyu Baek, and Koung-Suk Kim
- Abstract
The welding which is one of material joining methods plays an important role for development of the modern industry. The welding has several advantages such as high joint effect, high airtightness, and reduction of the materials being used. Nowadays, the applying or loading condition of the plates which are used for various mechanical structures becomes various. For applying the plates to the industrial field, its characteristics by tensile or compressive testing should be measured. Especially, the stress distribution at the welding part must be measured. During welding process, the thermal damage causes several types of defect including porosity, crack, insertion of impurities. A crack at the welding part results from these defects so that the mechanical structures could be destructive. In this paper, the butt welded S30400(STS304 in KS) specimen is prepared and the stress distribution at the welding part is measured by electronic speckle pattern interferometry (ESPI). [ABSTRACT FROM AUTHOR] more...
- Published
- 2007
- Full Text
- View/download PDF
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