• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1019-1023
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• 2006

Conventional methods for reducing vibration in engineering designs may be undesirable in conditions where size or weight must be minimized, or where complex vibration spectra exist. Fe-Mn Damping alloy with a combination of high damping capacity and good mechanical properties can provide attractive technical and economical solutions to problems involving seismic, shock and vibration isolation. We have studied the noise and vibration characteristic of Dampalloy and checked Dampalloy reduced noise about 3.9dB and vibration about 15.9 times as compared conventional material through laboratory research. With this result, we obtained a good possibility of material substitution about the bridge expansion joint

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.95-102
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• 1997

Jointless bridge is a new construction method applicable to bridge of short length. In the jointless bridge expansion of superstructure due to thermal effect was absorbed in the flexible pile-type abutment in stead of expansion joint in the conventional bridges. By removing expansion joint, it retards deterioration and extends life time of bridge. In this paper, jointless bridge of steel box girder type was studied through finite element analysis. Stress variations of superstructure and pile due to thermal effect was studied for the two span continuous integral bridge of 80m length and the results of analysis was presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.10-15
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• 2017

The refraction expansion joints have been newly developed by complementing the problems of shock, noise, replaceability, displacement in the direction perpendicular to bridge, vertical difference, which are problems of existing expansion joints. The Refraction expansion joints are characterized by continuous surfaces with small impact and low noise. The behavior of the Refraction expansion joints performs the bridge expansion behavior by rotation of the link. In the rotational behavior of the link, the bolt is the central axis of the behavior. Therefore, it can be said that the durability of the bolt is very important. However, the theoretical and experimental verification of the bolt durability of the Refraction expansion joint is lacking. In this paper, to verify the fatigue durability of the bolt, test specimens with a 300 mm Refraction expansion joint were fabricated. A strain gauge dedicated to the bolt was installed inside the manufactured test specimen bolt. The test method was applied in accordance with KS F 4425. The fatigue durability of the bolts assembled inside the diaphragm expansion joint was confirmed by the repeated fatigue test of 2,000,000 cycles.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.138-144
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• 2004

The initiation and the propagation of solder joint crack depend on its environmental conditions, such as high temperature creep and thermal fatigue. Creep is known to be the most important factor for the mechanical failure of solder joints in micro-electronic components and micro-systems. This is mainly caused by the different thermal expansion coefficients of the materials used in the micro-electronic packages. To determine the reliability of solder joints and consequently the electronic components, the characterization of the creep behavior of this group of materials is crucial. This paper is to apply the theory of creep into solder joints and to provide related technical information needed for evaluation of reliability of solder joint to failure. 63Sn-37Pb solder was used in this study. This paper experimentally shows a way to enhance the reliability of solder joints.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.5
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• pp.852-859
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• 1996

The factors and mechanism of arm surface changes were analyzed by regression analysis for the relationship between changes in arm joint angle and arm surface changes, according to the direction of upper extremity motion. Body surface change patterns among subjects were tested also. Experiments were carried out on 3 female subjects of different body types to examine 26 motions in 4 directions for 4 upper extremity parts. The major conclusions of the study are as follows: 1. The expansion or contraction of arm surface length depends on the direction of upper extremity motion. 2. Arm surface length changes by linear expansion or contraction according to the joint angle of the direction of motion. The mechanism of arm surface changes is represented by a linear relation between arm surface changes and the (actors of the direction of upper extremity motion and arm joint angle. 3. Arm surface length shows the same pattern of body surface changes regardless of body type. A quantitative model of body surface changes at upper extremity should be developed for functional sleeve design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.1
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• pp.241-254
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• 2002

Though there are many kinds of type in the expansion joint of bridges, Transflex joint was usually used from 1970's to 1980's. But it made of rubber is needed to exchange to new one often because of the breakage by wheel load. This study performed the safety estimation which is to exchange the transflex joint to finger joint kept the part of situ-cast-concrete. The standard of finger joint is same as that of transflex joint, we investigated the safety of finger joint with experimental results and FEM (Finite element method) analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.424-429
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• 2018

In this study, an expansion joint that is susceptible to waterhammer was tested for its vibration durability. The operation data for the hydraulic actuator was the expansion length of the expansion joint when the waterhammer occurred. In the case of the vibration durability test, the internal temperature status of the expansion joint was assumed to be a stress factor and a lifespan prediction model was assumed to follow the Arrhenius model. A test was carried out by increasing the internal temperature status at $30^{\circ}C$, $50^{\circ}C$, and $65^{\circ}C$. By a linear transformation of the lifespan data for each temperature, a constant value and activation energy coefficient was induced for the Arrhenius equation and verified by comparing the value of a lifetime prediction model with the experimental value at $85^{\circ}C$. The failure modes of the ongoing or finished test were leakage, bellows separation, and internal deformation. In the future, a composite lifespan prediction model, including two more stress factors, will be developed.

• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.213-223
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• 2017

Bridges are lifeline and integral components of transportation system that are susceptible to seismic actions, their vulnerability assessment is essential for seismic risk assessment and mitigation. The vulnerability assessment of bridges common in Pakistan is very important as it is seismically very active region and the available code for the seismic design of bridges is obsolete. This research presents seismic vulnerability assessment of three real case simply supported multi-span reinforced concrete bridges commonly found in northern Pakistan, having one, two and three bents with circular piers. The vulnerability assessment is carried through the non-linear dynamic time history analyses for the derivation of fragility curves. Finite element based numerical models of the bridges were developed in MIDAS CIVIL (2015) and analyzed through with non-linear dynamic and incremental dynamic analyses, using a suite of bridge-specific natural spectrum compatible ground motion records. Seismic responses of shear key, bearing pad, expansion joint and pier components of each bridges were recorded during analysis and retrieved for performance based analysis. Fragility curves were developed for the bearing pads, shear key, expansion joint and pier of the bridges that first reach ultimate limit state. Dynamic analysis and the derived fragility curves show that ultimate limit state of bearing pads, shear keys and expansion joints of the bridges exceed first, followed by the piers ultimate limit state for all the three bridges. Mean collapse capacities computed for all the components indicated that bearing pads, expansion joints, and shear keys exceed the ultimate limit state at lowest seismic intensities.

• Journal of the Korean Society for Railway
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• v.7 no.3
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• pp.283-289
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• 2004

According to continuos welded rails on a bridge, temperature changes bring about the expansion of the bridge deck adding axil forces on the track. Moreover, the ballast on the bridge deck expansion joint is moved due to the bridge deck. If bridge decks are longer, the influence is greater, loosening ballast, causing track irregularities, and deteriorating passengers' comfort. Considering structure of bridge itself and tolerance of track irregularities caused by the loosened ballast on bridges, the maximum length of a deck should be less than 80m, which is the same as the standard of the French railway. In this study, an interaction between the expansion related to the bridge length and irregularity in longitudinal level referring to measurements and maintenance works performed in the high-speed railways was analyzed. This research shows that installation of sliding plate or vertical ballast stopper is not a good option since it is difficult to install. On the other hand, installation of movable fastener or gluing is easy but its influence is insignificant. To conclude, switch tie tamping or manual tamping is more effective than others.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.12a
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• pp.412-416
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• 2003

This paper introduces a new joint signed expansion method for computing simultaneous scalar multiplication on an elliptic curve and a modified binary algorithm for efficient use of the new expansion method. The proposed expansion method can be also be used in cryptosystems such as RSA and EIGamal cryptosystems.