• Magazine of the Korea Concrete Institute
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• v.17 no.1 s.84
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• pp.18-21
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• 2005

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.20.1-20.1
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• 2003

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.11a
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• pp.107-108
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• 2013

• Proceedings of the Materials Research Society of Korea Conference
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• 2004.05a
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• pp.40-40
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• 2004

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.188-195
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• 2014

This paper was evaluated the rheology properties according to each step of paste, mortar and HPFRCC as a part of the basic study to development of sprayed high performance fiber reinforced cementitious composites(HPFRCC) for protection and blast resistant. Rheology test results in step of paste, in case of GGBFs and FA, it showed that the plastic viscosity and yield stress reduced gradually according to the increase of mixing rate, and in case of SF, the plastic viscosity and yield stress increased radically starting from the mixing rate of 10%. Rheology test results in step of mortar, type of aggregates, it showed that particle shape and grading of aggregate is influence on plastic viscosity and yield stress, and change of volume ratio is influence on plastic viscosity than yield stress. Fluidity and rheology test results in step of HPFRCC, if after a fiber mixed, it showed that viscosity agent is more effective to improve the fluidity and fiber dispersion than superplasticizer.

• Journal of Ocean Engineering and Technology
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• v.24 no.4
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• pp.23-31
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• 2010

The flow around a remotely-operated vehicle (ROV) has been investigated numerically to improve the resistant performance by modifying the hull form of the ROV. In the case of the base hull form considered in this study, form drag rather than friction drag was the dominant component of total drag. Subsequently, the surfaces that were most susceptible to local pressure effects were modified to give them a more streamlined shape. Eleven different hull forms were chosen to undergo surface modification for drag reduction. In addition, four different boat-tail appendages with different slant angles were installed at the stern to reduce the wake vortices that are induced by the local regions of very low pressure. Consequently, a total of 11 different hull forms for drag reduction were considered. The final hull form, which combined the hull for which surface modification resulted in the lowest drag with a boat-tail appendage with a 15-degree slant angle, resulted in a drag reduction of 20%.

• Journal of the Korean Institute of Gas
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• v.26 no.1
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• pp.27-33
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• 2022

As the scale of explosions diversifies along with the expansion of gas handling and storage facilities, studies on explosion-proof facilities in preparation for accidents is being actively conducted. The gastight door blocks the expansion pressure caused by blast waves or internal fires, and at the same time protects the personnel and equipment inside. For gastight doors, the regulations related to explosion-proof design are not clearly presented, and studies on the explosion pressure resistance performance evaluation of the facility are insufficient. In this study, the gastight door was modeled in a 3D shape with reference to the regulation ASTM regarding the gastight door standard. Afterwards, evaluation for blast-resistant performance of gastight door using Numerical simulation was evaluated by using ANSYS Explicit Dynamics to compare the deformation.

• Journal of Information Processing Systems
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• v.9 no.2
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• pp.271-286
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• 2013

Recently, a pixel-chaotic-shuffling (PCS) method has been proposed by Huang et al. for encrypting color images using multiple chaotic systems like the Henon, the Lorenz, the Chua, and the Rossler systems. All of which have great encryption performance. The authors claimed that their pixel-chaotic-shuffle (PCS) encryption method has high confidential security. However, the security analysis of the PCS method against the chosen-plaintext attack (CPA) and known-plaintext attack (KPA) performed by Solak et al. successfully breaks the PCS encryption scheme without knowing the secret key. In this paper we present an improved shuffling pattern for the plaintext image bits to make the cryptosystem proposed by Huang et al. resistant to chosen-plaintext attack and known-plaintext attack. The modifications in the existing PCS encryption method are proposed to improve its security performance against the potential attacks described above. The Number of Pixel Change Rate (NPCR), Unified Average Changed Intensity (UACI), information entropy, and correlation coefficient analysis are performed to evaluate the statistical performance of the modified PCS method. The simulation analysis reveals that the modified PCS method has better statistical features and is more resistant to attacks than Huang et al.'s PCS method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.3
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• pp.131-139
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• 2001

Experimental programs were accomplished to improve and evaluate the structural performance of RC frame structures with masonry infilled wall, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility etc. Test variables are restraining factors of frame, with or without masonry infilled wall, and masonry method. Six reinforced concrete rigid frame and masonry infilled wall were tested and constructed in one-third scale size under vertical and cyclic loads simultaneously. Based on the test results, the following conclusions can be made. For masonry infilled wall with restraining factors of frame(IFWB-1~3), cumulated energy dissipation capacities were increased by 1.35~1.60 times in comparision with that of masonry infilled wall(IFB-1) at final stage of testing. For masonry infilled wall with restraining factors of frame, maximum horizontal capacities were increased by 1.91~2.24 times in comparision with that of rigid frame.

• Wind and Structures
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• v.39 no.1
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• pp.71-84
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• 2024

The wind-resistant performance of bridges is generally evaluated based on the strip assumption. For the arch rib of arch bridges, the situation is different due to the curve axis and the variable cross-sectional size. In the construction stage, the arch rib supported by a cable system exhibits flexible dynamic characteristics, and the wind-resistant performance attracts specially attention. To evaluate the wind-induced vibration of an arch rib with the maximum cantilever state, the finite element model was established to compute the structural dynamic characteristics. Then, a three-dimensional (3D) fluid-solid coupling analysis method was realized. After verifying the reliability of the method based on a square column, the wind-induced vibration of the arch rib was computed. The vortex-induced vibration (VIV) performance of the arch rib was focused and the flow field characteristics were discussed to explain the VIV phenomenon. The results show that the arch rib with the maximum cantilever state had the possibility of VIV at high wind speeds but the galloping was not observed. The lock-in wind speeds were larger than the results based on the strip assumption. Due to the vibration of arch rib, the frequency of shedding vortices along the arch axis trended to be uniform.