• Proceedings of the Korea Concrete Institute Conference
• /
• 1992.04a
• /
• pp.53-58
• /
• 1992

This research is related to the experimental investigation of the inelastic behavior of R/C columns with high strength concrete. A total of eight specimens have been tested with different span ratios, steel reinforcements and load applications. Through tests bending moments were applied incrementally while axial forces being kept constantly at 80 tons. Careful observation were given to initial crack formation, crack patterns and propagation paths. Comparative studies have been made on the load carrying capacity for R/C columns with high strength concrete versus normal strength concrete.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.341-344
• /
• 2005

Recently, the application of Rapid Setting Cement has been gradually increased as an important construction. However, Rapid Setting Cement shows brittle failure. Therefore, in this study, tests are carried out using Rapid Setting Cement containing fiber in order to improve such a poor property. silica-cement ratio are varied. According to experimental results, Fiber reinforced Rapid -Setting Cement showed the high ductility and strain capacity regardless of silica-cement ratio. With 0.5 silica-cement ratio, a bending strength is the highest.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1990.10a
• /
• pp.69-72
• /
• 1990

This research is related to the experimental investigation of the inelastic behavior of reinforced concrete columns. A total of 12 specimens have been cast with different span ratios, steel reinforcements and load applications. Through the tests axial forces have been kept constantly at 40 tons while the bending moments were applied incremently and careful observations were given to the initial crack formation, crack pattern and propagation.

• Aerospace Engineering and Technology
• /
• v.3 no.1
• /
• pp.170-178
• /
• 2004

This paper deals with six degree-of-freedom HILS(hardware-in-the-loop-simulation) of KSR-III rocket using a TAFMS(three axis flight motion simulator). This TAFMS HILS test is accomplished before main HILS tests in order to verify the control stability in the presence of TAFMS dynamic effects. The TAFMS HILS test includes initial attitude holding tests for INS initial alignment procedures, timer synchronization tests with an auxiliary lift-off signal, real-time calibration tests using an external thermal recorder, open-loop TAFMS operating tests, and final closed-loop TAFMS HILS tests using the TAFMS attitude measurements as inputs to the closed control loop. The HILS tests are accomplished for several flight conditions composed with nominal flight condition, TWD effect added condition, slosh modes and/or bending modes existing condition, and windy condition, etc.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2153-2162
• /
• 2011

The goal of this Paper is to reduce rail's wear in curved track by applying an additional surface layer material(High hardness and High resistance capacity of wear) on the top of the railhead. In order to evaluate appropriation of a coating material, experimental tests such as the varieties of fundamental properties tests (hardening, wear, tensile, and bending) and RCF(rolling contact fatigue)test were performed to establish fatigue wear and damage mechanism. As a result, wear performance of coating rail is better than heated rail about 6times and normal rail about 8~9times.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.1979-1983
• /
• 2011

FRP(Fiber Reinforced Plastic) support insulators for DC(direct current) were developed and their electrical and mechanical characteristics were investigated. Electrical tests were carried out to measure flashover voltages under common use frequency condition. Tensile and bending tests were performed for the mechanical characteristics. The test results showed that FRP support insulators have superior voltage resistances and strengths to porcelain insulators. Field test also is carried out to measure adaptation and to compensate the defect. The test result showed that a new product has no defect in electrical and mechanical.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.1
• /
• pp.216-221
• /
• 2001

In this study, the effects of nitriding methods and times on the fatigue strength of SACM 645 steel were investigated. The rotary bending tests were carried out to obtain and compare the fatigue strengths of plasma ion nitrided specimens and gas nitride specimen. The 70 hr. gas nitrided specimen had the highest fatigue strength of 1.05$\times$$10^3$ MPa over the 40 hr., 70 hr. and 90 hr. plasma ion nitrided specimens, which had the fatigue strength of 3.48$\times$$10^2$, 4.57$\times$$10^2$ and 4.64$\times$$10^2$ respectively. Also, the microhardness tests were conducted to measure the effective case depths. The plasma ion nitrided specimens showed much higher surface hardness values than the gas nitrided specimen overall.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.3
• /
• pp.152-160
• /
• 1993

This paper presents experimental study of the static and dynamic fracture toughness behavior of a A1-6061 aluminum alloy reinforced alumina( .delta. -A1$_{2}$0$_{3}$) whiskers with 5%, 10%, 15% volume fraction. The static fracture tests using three-point bending specimen were performed by UTM25T. And drop weight impact tester performing dynamic fracture tests was used to measure dynamic locads applied to a fatigue-precracked specimes. The oneset of crack initiation was detected uwing a strain gage bonded near a crack tip. The value of static fracture toughness $K_{IC}$ and dynamic fracture toughness $K_{ID}$ were decided on the basis of linear elastic fracture mechanics. The effects of fiber volume fraction and loading on fracture toughness were investigated. The distribution of whiskers, bonding state and fracture interfaces involved in void, fiber pull-out state were investigated by optical microscopy(OM) and scanning electron microscopy(SEM)

• Proceedings of the Korea Concrete Institute Conference
• /
• 1990.04a
• /
• pp.39-44
• /
• 1990

This experimental study is performed by using artificial lightweight aggregate manufactured in laboratory, and the test results of it are compared with those using foreign materials in respect of design compressive strength, unit weight. The tests on strength characteristics such as bending, splitting tensile strength and on mechanical characteristics including σ-εcurve, elastic modulus, poisson's ratio are performed to provide the fundamental data required for the design. From this study, it is possible to obtain the high-strength concrete having compressive strength of 500 kg/㎠ and unit weight of 1.85-2.0 t/㎥. And also it is recommended that sandlightweight concrete having high specfic strength is more practical for general use.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.130-135
• /
• 2007

The mechanical characteristics of three types of core with two-dimensional isotropic patterns-triangular, hexagonal and starcell-were studied in applications to sandwich structures. The Young's modulus and shear modulus were calculated for the three core types in the direction normal to the faces. The compressive buckling strength and shear buckling strength were calculated by modeling each cell wall of the core as a plate under compressive or shear load. To verify this model, tests were conducted on scaled specimens to measures the compressive buckling strength of each core. The bending flexibilities of the three cores were also studied. Compliances for the three cores were measured using biaxial flexural tests. The three isotropic core patterns exhibited distinct characteristics. In the direction normal to the faces, all three cores had the same stiffness. However, the starcell core exhibited high flexibility compared to the other cores, indicating potential for application to curved sandwich structures.