• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.221-222
• /
• 2007

The test method on materials of electrical power cable are used in accordance with 18 specifications of IEC, ICEA, KS and KEPCO Spec. The validation of test methods were checked and established by solving the problems occurred during the test. These tests are tensile strength, hot creep, shrink back, environmental stress cracking, flammability, oxygen index, absorption coefficient, differential scanning calorimetry, amount of ion in semiconductor, void, amber, contaminant and water tree etc. The performance test of power cable made by A, B, C, D company were evaluated and compared.

• International Journal of Highway Engineering
• /
• v.15 no.5
• /
• pp.57-64
• /
• 2013

PURPOSES : It is to evaluate lightweight soil as a subgrade material based on mechanical tests and calculation of pavement performance. METHODS : In this research, various contents of cement and air foam are used to make lightweight soil using wasted dredged soil. Uniaxial compressive strength test is conducted to evaluate strength of 7 and 28 day cured specimens. Secant modulus was calculated based on the stress and strain relationship of uniaxial compressive strength test. Resilient modulus test was measured using by repeated triaxial compression test. The measured resilient modulus was used in layered elastic program to predict fatigue and rutting life at a given pavement structure. RESULTS : Uniaxial compressive strength increases as cement content increases but decrease as air foam content increases. Resilient modulus also increases as cement content increases and decrease as air foam content decrease. CONCLUSIONS : It is concluded that dredge clay soil can be used as subgrade layer material using by lightweight treated soil method.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.11
• /
• pp.124-131
• /
• 1996

The dynamic material property of Mn-B ally high-strength steel is investigated through the rod impact test which is one of simple test methods for the analysis of the material behavior under high-strain-rate. Rod impact test is performed to produce the deformed shape of rod and analyzed by the one-dimensional theory based on conservation law and the two-dimensional hydrocode AUTODYN-2D. The dynamic yield stress is determined and compared with the static yield stress to investigate the strain-rate sensitivity of Mn-B alloy high-strength steel.

• Transactions of Materials Processing
• /
• v.3 no.1
• /
• pp.51-62
• /
• 1994

Cup drawing test and U-bending test were performed to evaluate the friction characteristics of sheet materials for the different deformation modes involved in stamping process. The coefficient of friction calculated from the each test was compared to that obtained from the draw bead friction test. It was clarified that the cup drawing test could be simply used for evaluating the friction characteristic of sheet material in deep drawing process with high contacting pressure. However the U-bending test is suitable to evaluate the frictional characteristic of sheet material in bending process with low contacting pressure.

• Journal of the Korean Society for Advanced Composite Structures
• /
• v.5 no.1
• /
• pp.16-21
• /
• 2014

In the study, tensile, compression and in-plane tests about longitudinal direction of glass fiber were performed. Also, to obtain the material properties of GFRP fabric composite, tensile test was performed. All test were performed by the test method of ASTM. Maximum compressive strength was smaller than the maximum tensile strength at the longitudinal direction test results. Elastic modulus of the tensile and compressive was almost similar at the compression test results in the longitudinal direction. Based on the GFRP fabric composite test results, GF91 was showed good performance at maximum compressive, maximum strain and elastic modulus.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.2
• /
• pp.300-312
• /
• 1993

The material deterioration of service-exposed boiler tube steels in fossil power plant was evaluated by using the electrochemical technique namely, modified electrochemical potentiokinetic reactivation(EPR). It was focused that the passivation of Mo$_{6}$C carbide which governs the mechanical properties of Mo alloyed steels did not occur even in the passivity region of steel in sodium molybdate solution and the reactivation peak current (Ip) observed as the result of non-passivation indicating the precipitation of Mo$_{6}$C carbides. To obtain the optimal test conditions for the field test by using the specially designed electrochemical cell, the effects of scan rate, the surface roughness and the pH of electrolyte on Ip value were also investigated. Furthermore, the change of mechanical properties occurred during the long time exposure at high temperature was evlauated quantitatively by small punch(SP) tests and micro hardness test taking account of the metallurgical changes. It is known that reactivation peak current (Ip) has a good relationship with Larson-Miller Parameter(LMP) which represents the information about material deterioration occurred at high temperature environment. In addition it was possible to estimate the ductile-brittle transition temperature (DBTT) by means of the SP test. The Sp test could be, therefore, suggested as a reliable test method for evaluating the material degradation of boiler tube steels. From the good correaltion between the SP DBTT and Ip values shown in this study, it was knows that the change of mechanical properties could be evaluated non-destructively by measurring only Ip values.ues.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.7
• /
• pp.1241-1249
• /
• 2002

The extent of materials deterioration can be evaluated accurately by mechanical test such as impact test or creep test. But it is almost impossible to extract a large test specimen from in-service components. Thus material degradation evaluation by non-destructive method is earnestly required. In this paper, the material degradation for virgin and several aged materials of a Cr-Mo-V steel, which is an candidated as structural material of the turbine casing components for electric power plant, is nondestructively evaluated by reactivation polarization testing method. And, the results obtained from the test are compared with those in small punch(SP) tests recommended as a semi-nondestructive testing method using miniaturized specimen. In contrast to the aged materials up to 1,000hrs which exhibit the degradation behaviors with increased ${\Delta}[DBTT]_{SP}$, the improvement of mechanical property can be observed on the 2,000hrs and 3,000hrs aged materials. This is because of the softening of material due to the carbide precipitation, the increase of ferritic structures and the recovery of dislocation microstructure by long-time heat treatment. The reactivation rates($I_R/I_{Crit},\;Q_R/Q_{Crit}$) calculated by reactivation current densityt ($I_R$) and charge($Q_R$) in the polarization curves exhibit a good correlation with ${\Delta}[DBTT]_{SP}$ behaviors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2012.10a
• /
• pp.546-552
• /
• 2012

This paper is a study on squeal noise simulation under the consideration of temperature and pressure dependent material properties of friction material. For this, data of pressure and temperature dependent material properties of lining is achieved by using lining data base and exponential curve fit. Complex eigenvalue analysis is performed for predicting squeal noise frequency and instability and chassis dynamo test is performed for achieving squeal noise frequency, sound pressure level, occurrence temperature & pressure. Initial multi models are composed for considering complex interface conditions such as pad ear-clip, piston-housing and guide pin-torque member. The simulation result of base models is compared with the test result. Squeal noise simulation under the consideration of temperature and pressure dependent material properties of friction material is performed and analyzed using multi models. And additional condition is disc material property variation. Entire simulation conditions are combined and analyzed. Finally, this paper proposes direction of the warm squeal noise model.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.297-304
• /
• 2002

This study is about penetrability of Micro Cement(MC) used for ground improvement. In this study, the characteristics of chemical grouting such as solidification, penetrability were analyzed experimentally by changing permeability of ground, grain size and relative density of grout material. For evaluating applicability of grout material, solidification test and penetrability test were performed. From the results of the tests, effective solidification ratio and penetrability ratio of MC was each 75%, 86% to be excellent when ground permeability was in the range of 10$^{-2}$ and 10$^{-4}$ cm/sec. Otherwise, those of Ordinary Portland Cement(OPC) were both lower than 50% to be poor. When penetrability of grout material is needed for improvement of dam foundation and soft ground, application of MC Is much superior to that of the other materials. The results of the grouting tests in the water flowing ground show that solidification effect of long gel-time grout material is excellent as injection pressure increases when groundwater velocity is relatively low. But when groundwater velocity is relatively high, solidification effect of long gel-time grout material is very poor because most grout materials are outflowed. Therefore, as groundwater velocity is high, effective solidification ratio of long gel-time grout material is better than that of short gel-time grout material, also penetration distance of long gel-time grout material is longer than that of short gel-time grout material.

• Fire Science and Engineering
• /
• v.31 no.6
• /
• pp.74-82
• /
• 2017

Fires in buildings built using sandwich panels are difficult to extinguish, and the damage caused by the fire spreading through the inner core material is extensive. Sandwich panels consist of a nonflammable material on both sides of an insulation material. The types of insulation material include organic and inorganic insulation materials, but the former are used in more than 80% of the case. Organic insulation is economically advantageous compared to inorganic insulation, but it is vulnerable to fire. Therefore, the damage caused by sandwich panel fires is higher than that for general fires. In the case of the noxious gas analyzer test, the panel is tested with three round holes having a diameter of 25 mm, in order to determine the risk of the core material, but the cone calorimeter test is carried out using a sandwich panel. In this study, the cone calorimeter test was conducted to examine the fire risk of the composite material when heated on a nonflammable surface, exposed to the core material through a hole, and heated directly the core material. The type of organic insulation employed was flame retardant EPS (Expanded Polystyrene), and the test specimens were tested in three types of sandwich panel, a perforated sandwich panel and single core material. The purpose of this study is to propose a method of measuring the fire risk of the core materials of composite materials using the cone calorimeter test.