• Geomechanics and Engineering
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• v.12 no.1
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• pp.111-125
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• 2017

Swelling and shrinkage characteristics of expansive fine grained soil cause volumetric changes followed by distress and damage to the structures. Soil stabilization can be explained as the alteration of the soil properties by chemical, mechanical or any other means in order to enhance the engineering properties of the soil. Utilization of industrial wastes in soil stabilization is cost effective and environment friendly. This paper presents an experimental study on stabilization of expansive soil using industrial wastes, viz. fly ash and dolochar. The paper includes the evaluation of engineering properties like unconfined compressive strength and California bearing ratio (CBR) of expansive soil collected from Balasore district of Odisha stabilized with fly ash and dolochar in different proportions and to predict the influence of these additives on engineering properties and strength characteristics of expansive soil. Both fly ash and dolochar were found to increase the CBR and decrease many index properties such as liquid limit, plastic limit, plasticity index, swelling index and UCS, thus enhancing the strength parameters of expansive soil.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.1-7
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• 2015

As energy consumption of building and the reduction of carbon dioxide emissions have been emphasized, phase change materials(PCM) have been introduced as building materials due to its high heat storage performance. Using shape-stabilizing technique, octadecane/xGnP shape-stabilized PCM(SSPCM) can prevent leakage and improve heat storage performance. The objectives of this study are to propose mix design method of concrete mixed with SSPCM and to evaluate mechanical behaviors of the concrete mixed with SSPCM manufactured according to the proposed mix design. Based on the previously reported material test result, the existing mix design of plain concrete(Concrete standard specification, 2009) is modified to consider reduction of strength in concrete due to the addition of SSPCM. To verify the proposed mix design, specimens are fabricated according to the proposed mix design and axial strength tests and three-point loading tests are performed. Test results show that compressive strengths of the tested specimens reach the designed strength even when two different mix ratios of SSPCM are used. From three-point loading tests, flexural stresses decrease as mix ratio of SSPCM increases.

• Journal of Biomedical Engineering Research
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• v.38 no.5
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• pp.248-255
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• 2017

Polyurethane/polyethylene glycol(PU/PEG) hybrid scaffolds with various concentrations of PEG (0 to 50wt%) were prepared by electrospinning to evaluate the mechanical properties and the biocompatibility of the PU/PEG blend scaffolds. The 12wt% PU/PEG polymers were studied due to the absence of beads. The ultimate tensile strength of 12wt% PU was $8.2{\pm}0.5MPa$. The strength increased to $9.2{\pm}0.7MPa$ when 10% PEG was added to PU. However, the dry and the wet strength of PU/PEG scaffolds began to decrease dramatically when the PEG content was more than 10wt%. No cytotoxicity was observed for all the PU/PEG scaffolds investigated, indicating that the PU/PEG hybrid scaffolds are clinically safe and effective to small-diameter vascular grafts. In addition, the L-929 cells attached and proliferated well on the PU/PEG hybrid scaffolds.

• Journal of Biomedical Engineering Research
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• v.39 no.3
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• pp.134-139
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• 2018

One of the most common problems with pedicle screw system is pullout of the screw. This study was performed to evaluate the pullout strength and driving torque of newly designed pedicle screws. The design of three type screws were standard pedicle screw, which had single lead threaded and single pitched design (Type A), single pitched and dual lead threaded pedicle screw (Type B), dual pitched and dual lead threaded pedicle screw (Type C), respectively. The tests were performed in accordance with the ASTM standards using polyurethane (PU) foam blocks. There was no significant difference in pullout strength among three types of screw. Type B and Type C exhibited higher insertion torque and removal torque than Type A, respectively (p<0.05). Pedicle screws newly developed with dual pitched and dual lead threaded design showed higher driving torque without decrease in pullout strength compared to the standard pedicle screw and could be inserted more rapidly with the same number of revolutions.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.461-464
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• 2008

This study investigated mechanical properties of the concrete using standard contents which was existent fibers in korea to apply the method for reducing crack of the non-reinforced concrete for the public space of an apartment with a fiber reinforcement. Results were summarized as following. The slump was slightly declined corresponding to the increase of the surface area and bridge effect of the fibers. For properties of the hardened concrete, the compressive strength was slighty reduced caused by the decrease of bonding strength between fiber and cement paste. The tensile strength was little increased according to bridge effect of the fibers, and the flexible strength and length change due to the drying shrinkage did not showed remarkable tendency.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1195-1203
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• 2006

Water that is treated by passing through a magnetic field of certain strength is called Magnetic Field Treated Water(MFTW). Previous research indicate that use of MFTW can save 5% of cement dosage, decrease bleeding of concrete, and improve resistance to freezing. The reason why MFTW can improve characteristics of concrete can be explained by the molecular structure of water. Magnetic force can break apart water clusters into single molecules or smaller ones, therefore, the activity of water is improved. While hydration of cement particles is in progress, the MFTW can penetrate the core region of cement particles more easily. Hence, hydration takes place more efficiently which in turn improves concrete compressive strength. Test results demonstrate that the compressive strength of the sodium silicate cement grout homogel increases by approximately 20 - 50% by using the MFTW.

• Journal of muscle and joint health
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• v.11 no.2
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• pp.127-135
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• 2004

Purpose: The purpose of this study was to explore the effects of aquatic exercise program on pain, flexibility, grip strength, self-care activities, helplessness in osteoarthritis patients. Methods: This program was carried out three times a week for 6 weeks by 3 groups of patients among 42 patients in regular swimming pool. Data were analysed by paired t-test for pre and post comparison. Results: There were significantly improved in pain flexibility, grip strength, self-care activities and helplessness after the program. However no significant differences were found in fatigue, difficulty of daily living activities and depression. Conclusion: Aquatic program was proved to be an effective nursing intervention to increase the self-care activities flexibility and grip strength, and to decrease pain and helplessness in osteoarthritis patients.

• Structural Engineering and Mechanics
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• v.9 no.5
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• pp.469-482
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• 2000

A numerical study using nonlinear finite element analysis is performed to investigate the behavior of isolated reinforced concrete walls subjected to combined axial force and in-plane and out-of-plane bending moments. For a nonlinear finite element analysis, a computer program addressing material and geometric nonlinearities was developed. Through numerical studies, the internal force distribution in the cross-section is idealized, and then a new design method, different from the existing methods based on the plane section hypothesis was developed. According to the proposed method, variations in the interaction curve of the in-plane bending moment and axial force depends on the range of the permissible axial force per unit length, that is determined by a given amount of out-of-plane bending moment. As the out-of-plane bending moment increases, the interaction curve shrinks, indicating a decrease in the ultimate strength. The proposed method is then compared with an existing method, using the plane section hypothesis. Compared with the proposed method, the existing method overestimates the ultimate strength for the walls subjected to low out-of-plane bending moments, while it underestimates the ultimate strength for walls subject to high out-of-plane bending moments. The proposed method can address the out-of-plane local behavior of the individual wall segments that may govern the ultimate strength of the entire wall.

• Steel and Composite Structures
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• v.24 no.5
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• pp.615-633
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• 2017

Fatigue crack initiated in welded tubular joints due to cyclic loading may produce harmful effect on the integrity of the tubular structures. To study such effect, both fatigue and static tests on nine circular tubular T-joint specimens made of carbon steel materials were carried out. The specimens were subjected to tensile loading in both fatigue and static tests. The load-displacement relation, the crack propagation and the failure mode of the specimens are all analyzed. The deterioration of the static strength of the cracked T-joints is also investigated and evaluated through an area reduction factor. Experimental results indicate that the static strength of a tubular T-joint with a surface crack seems to decrease slightly while a through crack has relatively remarkable effect on the reduction of the static strength. Additionally, experimental results also show that the toughness of the materials and the geometry of the specimens play an important role on the failure process of cracked tubular T-joints.

• Journal of the Microelectronics and Packaging Society
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• v.5 no.1
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• pp.7-18
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• 1998

In the flip chip interconnection on organic substrates using eutectic Pb/Sn solder bumps highly reliable Under Bump Metallurgy (UBM) is required to maintain adhesion and solder wettability. Various UBM systems such as 1$\mu$m Al/0.2$\mu$m Pd/1$\mu$m Cu, laid under eutectic Pb/Sn solder were investigated with regard to their interfacial reactions and adhesion proper-ties. The effects of numbers of solder reflow and aging time on the growth of intermetallic compounds (IMCs) and on the solder ball shear strength were investigated. Good ball shear strength was obtained with 1$\mu$m Al/0.2$\mu$m Ti/5$\mu$m Cu and 1$\mu$m Al/0.2$\mu$m ni/1$\mu$m Cu even after 4 solder reflows or 7 day aging at 15$0^{\circ}C$. In contrast 1$\mu$m Al/0.2$\mu$m Ti/1$\mu$m Cu and 1$\mu$mAl/0.2$\mu$m Pd/1$\mu$m 쳐 show poor ball shear strength. The decrease of the shear strength was mainly due to the direct contact between solder and nonwettable metal such as Ti and Al resulting in a delamination. In this case thin 1$\mu$m Cu and 0.2$\mu$m Pd diffusion barrier layer were completely consumed by Cu-Sn and pd-Sn reaction.