• Geomechanics and Engineering
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• v.18 no.4
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• pp.353-362
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• 2019

Soil-rock mixture (S-RM) is an inhomogeneous geomaterial that is widely encountered in nature. The mechanical and physical properties of S-RM are important factors contributing towards different deformation characteristics and unstable modes of the talus slope. In this paper, the equivalent substitution method was employed for the preparation of S-RM test samples, and large-scale triaxial laboratory tests were conducted to investigate their mechanical parameters by varying the water content and confining pressure. Additionally, a simplified geological model based on the finite element method was established to compare the stability of talus slopes with different strength parameters and in different excavation and support processes. The results showed that the S-RM samples exhibit slight strain softening and strain hardening under low and high water content, respectively. The water content of S-RM also had an effect on decreasing strength parameters, with the decrease in magnitude of the cohesive force and internal friction angle being mainly influenced by the low and high water content, respectively. The stability of talus slope decreased with a decrease in the cohesion force and internal friction angle, thereby creating a new shallow slip surface. Since the excavation of toe of the slope for road construction can easily cause a landslide, anti-slide piles can be used to effectively improve the slope stability, especially for shallow excavations. But the efficacy of anti-slide piles gradually decreases with increasing water content. This paper can act as a reference for the selection of strength parameters of S-RM and provide an analysis of the instability of the talus slope.

• Korean Journal of Exercise Nutrition
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• v.17 no.2
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• pp.25-34
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• 2013

This study was conducted to investigate the relationship between ACE gene polymorphism and muscle damage parameters after eccentric exercise. 80 collegiate males were instructed to take an eccentric exercise with the elbow flexor muscle through the modified preacher curl machine for 2 sets of 25 cycles (total 50 cycles). The maximal isometric strength, muscle soreness, creatine kinase (CK), and myoglobin (Mb) were measured before exercise, and 0, 24, 48, 72, and 96 hrs after exercise. The result showed that after the eccentric exercise, the maximal isometric strength significantly decreased by more than 50% (p < 0.001) and the muscle soreness, CK, and Mb significantly increased compared to those before the exercise (p < 0.001). The ACE gene polymorphism of the subjects was classified using real-time polymerase chain reaction (real-time PCR). The result showed that it consisted of 38 cases of type II (46.4%), 33 cases of type ID (43.4%), and 9 cases of type DD (10.2%). The Hardy-Weinberg equilibrium for ACE gene polymorphism was shown to have p = 0.653, which showed that each allele was evenly distributed. Although significant differences in the changes in the maximal isometric strength, muscle soreness, CK, and Mb were found according to time course (p < 0.001), no significant differences in the changes in the maximal isometric strength, muscle soreness, CK, and Mb were found according to ACE gene polymorphism. Furthermore, no significant difference in the changes in the muscle damage parameters was found according to interaction between ACE gene polymorphism and time course (p > 0.05). In conclusion, the level of the muscle damage parameters changed in the injured muscle after eccentric exercise, but these changes in the muscle damage parameters were not affected by ACE gene polymorphism. The result of this study indicates that ACE gene is not a candidate gene that explains muscle damage.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.505-508
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• 1999

To evaluate the strength of square reinforced concrete shot columns, thirty specimens were manufactured and tested under monotonically increasing concentric compression. The test parameters included the volumetric ratio of transverse reinforcement($\rho$h = 0.49~2.65), and concrete compressive strength (234, 437, 704 kgf/$\textrm{cm}^2$). Test results are shown that : (1) Behavior of high -strength concrete column is improved by providing increased volumetric ratio; and (2) ACI, Eq. is not proper to evaluate HSC short column strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.675-678
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• 2003

Experimental results for variation of concrete strength according to vibration time control for fresh concrete were given. Vibration velocity, time before vibration and vibrating time were used as experimental parameters. Compressive strength, split tensile strength, ana bond strength were investigated and then fracture surfaces of split tensile strength specimen were observed. From the experimental results, it could be concluded that there may be no decrease in concrete strengths if time before vibration will be sustained at least for more than 3 hours.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.322-325
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• 2007

Dent resistance is an important characteristic to avoid damage on automotive outer panels. From a practical point of view, dents can be caused in a number of ways. Considering doors as an example, denting can occur from stone impacts or from the careless opening of an adjacently parked vehicle door. Denting can occur where the door surface is smooth and may not have sufficient curvature to resist dent. These exterior body parts are designed to improve dent resistance using a combination of work hardening and bake hardening. In brief, dent is affected by the shape of the parts and the material properties such as yield strength, strain and thickness. In this work, forming of door outer panel is investigated by Taguchi method. Main parameters are yield strength, thickness, blank size, blank holding force and so on. For the given value of design parameters, forming analysis of the thirty six cases are carried out according to L18 orthogonal array. After comparing the performance by simple conversion of simulation results into dent resistance, the final suggestion of the forming parameters is verified for the best improvement of dent resistance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1187-1193
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• 2002

Anodic bonding process has been quantitatively evaluated based on the Taguchi analysis of the interfacial fracture toughness, measured at the interface of anodically bonded silicon-glass bimorphs. A new test specimen with a pre-inserted blade has been devised for interfacial fracture toughness measurement. A set of 81 different anodic bonding conditions has been generated based on the three different conditions for four different process parameters of bonding load, bonding temperature, anodic voltage and voltage supply time. Taguchi method has been used to reduce the number of experiments required for the bonding strength evaluation, thus obtaining nine independent cases out of the 81 possible combinations. The interfacial fracture toughness has been measured for the nine cases in the range of 0.03∼6.12 J/㎡. Among the four process parameters, the bonding temperature causes the most dominant influence to the bonding strength with the influence factor of 67.7%. The influence factors of other process parameters, such as anodic voltage and voltage supply time, bonding load, are evaluated as 18%, 12% and 2.3%, respectively. The maximum bonding strength of 7.23 J/㎡ has been achieved at the bonding temperature of 460$\^{C}$ with the bonding load of 45gf/㎠, the applied voltage of 600v and the voltage supply time of 25minites.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.768-776
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• 2006

Recently in spite of Development of Investigation machine, in Application of Geotechnical Properties by empirical recommendation to the Slope Stability Analysis. It is generally Application of convenience and conservative Geotechnical Properties by Borehole Shear Test(BST) in Representative Zone that Non-Division of Increase as the depth of Strength Parameters In Deep Weathered Zone. Therefore, it is become environment pollution and Non-Economical Slope Design to Application of convenience and conservative Geotechnical Properties. The production mechanism of Deep Weathered Zone is tend to Weathering Degree low and Strength increase by increase as the depth. it is realistic design that Division of Deep Weathered Zone and application Geotechnical Properties of Each Layer. In this Paper, Determined The Relationship of Strength Parameters between Standard Penetration Test(SPT), Borehole Shear Test(BST) and empirical recommendation also Applyed each strength parameters of divided zone to the Slope Stability Analysis by continuous Borehole Shear Test(BST) in Deep Weathered Zone during design of The 2nd Bridge Connection Road of Incheon International Airport.

• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.13-22
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• 2000

In order to resolve the problem of increasing traffic entailed by the economic development, road system is reorganization and new highways are built, and long span bridges over 40m are being constructed in environmental and aesthetic considerations. Most long span bridges that are currently being constructed are in general steel box girder and preflex girder bridges; however these types of breiges are less efficiency than PSC I-type girder bridges in terms of construction cost and maintenance. Therefore, in these study, structural efficiency of PSC I-type girders based on section parameters, concrete compressive strength and other design parameter is observed to develope new PSC I-type girder for long span bridges. As a results of analysis, most important design parameters that control the stress of the girder are found to be the top flange width and the height of girder. In this light, the relationship between the two variables is determined and cross-section details of the girder that most appropriates for the long span bridges are proposed. The use of high strength concrete appears to increase the general design span however the increase rate of the span from increasing concrete ultimate strength appears to be reduced depending on the span. Also, the optimal girder spacing is determined through the parameter studies of design span using the proposed girder.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.254-259
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• 2007

Dent resistance is an important characteristic to avoid damage on automotive outer panels. From a practical point of view, dents can be caused in a number of ways. Considering doors as an example, denting can occur from stone impacts or from the careless opening of an adjacently parked vehicle door. Denting can occur where the door surface is smooth and may not have sufficient curvature to resist dent. These exterior body parts are designed to improve dent resistance using a combination of work hardening and bake hardening. In brief, dent is affected by the shape of the parts and the material properties such as yield strength, strain and thickness. In this work, forming of door outer panel is investigated by Taguchi method. Main parameters are yield strength, thickness, blank size, blank holding force and so on. For the given value of design parameters, forming analysis of the eighteen cases are carried out according to L18 orthogonal array. After comparing the performance by simple conversion of simulation results into dent resistance, the final suggestion of the forming parameters is verified for the optimal improvement of dent resistance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.1131-1136
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• 2011

This study is performed on the acoustic emission parameters involved in a burst test for a CNG-vehicle fuel tank. A resonant AE sensor with a central frequency of 150 kHz was attached on the composite materials in the center of the fuel tank. The analysis of AE parameters such as hit, amplitude, count, duration, risetime, and signal strength during load holding was performed. The total count and total signal strength are effective tools for the damage evaluation of a CNG fuel tank.