• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.146-153
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• 2004

We compared the fatigue characteristics of weld metal with those of base metal, and not heat-treated with heat-treated. Also, we examined the influence of bead in a viewpoint of fatigue life. From the experimental results, it has been seen that the fatigue characteristics of welded specimens grinded the toe of bead are slightly better than not grinded. We have seen that the fatigue life is affected more by the stress concentration on the profile change in the weld toe rather than by residual stress influence, because heat-treated or not had almost no influence on the fatigue characteristics.

• IE interfaces
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• v.17 no.1
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• pp.13-21
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• 2004

In this study, the prototype of a system for checking risk-factor of NC machine is proposed. The proposed system can get the risk-related information by monitoring the status of real-time processes of NC machines. Using the information, the accidents can be prevented by the background process of an expert system tool. This paper consists of 2 parts: (1) the method for gathering data and definition of the risk-related factors of NC machines and (2) the procedure for finding the proper actions by using the forward chaining of a rule-base. Proposed system is implemented with C++ language under MS-windows.

• Tribology and Lubricants
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• v.14 no.3
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• pp.81-86
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• 1998

The purpose of this paper is to measure the rotational speed of tappet in OHC valve train system. Tappet has eccentricity about cam center, which induces the tappet rotation and prevents from wear. In this paper, the experimental test rig which composes of one cam system is developed to measure the tappet rotation by using the laser generating system, rotary encoder, optical fiber, and photo transistor. The direction of tappet rotation is judged from the oder of optical signal. As results of experiment, average and instant rotational speed and average rotation angle per one cam revolution are presented. Measured results show that eccentricity ratio is dominant factor for the tappet rotation, and tappet is rotated at the base circle.

• Mass Spectrometry Letters
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• v.2 no.3
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• pp.73-75
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• 2011

In the collisionally-activated dissociation of the proton-bound cluster ions of DNA base guanine (G) and cytosine (C), $G{\bullet}{\bullet}H^+{\bullet}{\bullet}C$, the abundance of [$CH^+$] ions was found to be higher than that of [$GH^+$] despite the fact that G has a higher proton affinity than C. This unexpected observation seems to demonstrate another example that the simple kinetic method scheme does not work. We suggest that a kinetic factor or detailed dynamics governing the proton transfer and dissociation should be carefully considered in the applications of the kinetic method to the proton affinity measurements.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.181-189
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• 2001

For the Tailor Welded Blank sheet used fur automobile body panel, the characteristics of fatigue crack propagation behavior were studied. The thickness of specimen was machined to be same (0.9+0.9mm) and different (0.9+2.0mm). As a base test, mechanical properties around welding zone were examined. The results indicated that there were no significant decreases in mechanical properties, but hardness around welding bead is 2.3 times greater than base material. The crack propagation rate was noticeably decreased around welding line and rapidly increased as it passed by welding line. Reviewing the shape of the crack propagation, crack width around welding line was wide around the welding zone due to retardation of crack growth, but it became narrow passing welding line due to decreased toughness. Elasto-Plastic analysis was performed by finite element analysis fur explaining the test results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.225-232
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• 1994

In this paper, a new approach for the induction machine control whih ensures producing maximum torque per ampere over the entire field weakening region is presented. In addition, the relation of the output torque capability with the leakage factor of the machine is examined. Also the smooth and precise transition into the field weakening operation can be achieved by adjusting the base speed for the field weakening operation according to the flux level, the current limit and the voltage limit. The proposed is verified through simulation and experiment for a 5hp laboratory induction motor drive system.

• Journal of Welding and Joining
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• v.14 no.2
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• pp.90-95
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• 1996

In order to investigate characteristics of surface fatigue crack propagation from a pit shaped surface defect which frequently exists around welded joints, SS400 steel with thickness of 12mm, which has been generally used for structure members, was welded with submerged-arc butt type and machined for both surface. An initial surface defect of pit shape with the aspect ratio of 2 was made on the specimen. The initial defect was located at 5 different zones over the weldment : weld metal zone, boundary between weld metal and HAZ, HAZ, boundary between HAZ and base metal. Characteristics of surface fatigue crack propagation from the defect on each region under the same loading condition were investigated and compared.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.166-173
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• 2001

Recommended seismic design guide for the flat bottom vertical-cylindrical oil storage tanks in KS B 6225 is presented. Under earthquake excitations, the hydrodynamic pressure exerted on the tank walls produces overturning moment which may cause either a failure of the anchors or a buckling of the tank shell near its base. The basis for establishing design loads due to hydrodynamic pressure is described including seismic zone risk map in Korea, zone coefficients and the essential facilities factor. This procedure for calculating applied compressive stress on the shell base subjecting to seismic load and for estimating the allowable buckling stress is described.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.551-555
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• 1997

IJnder earthquake excitations, the hydrodynamic pressure exerted on the flat bottom vertical-cylindrical oil storage tank walls produces overturning moment which may cause either a failure of the anchors or a buckling of the tank shell near its base. The basis for establishing design loads due to hydrodynamic pressure is described including seismic zone risk map in Korea. zone coefficients and the essential facilities factor. This procedure for calculating applied compressive stress on the shell base subjecting to seismic load and for estimating the allowable buckling stress is described. And seismic design program for the tanks is presented.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.11
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• pp.1053-1059
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• 2010

This paper treats the DIS (Digital Image Stabilization) problem subject to base motions such as translation, rotation and zoom. For the local motion estimation from a raw image, the Harris corner detection algorithm is exploited to extract feature points, and comparing those of consecutive images, the zoom ratio (scale factor) is computed. For the global motion estimation, an equivalent model is derived to account for a 3-dimensional composite motion from which the center point and Euler angle can be determined. Finally, the motion compensation follows. To show the effectiveness of the present DIS scheme, experimental results for synthetic images are illustrated.