• International Journal of Highway Engineering
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• v.20 no.3
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• pp.19-26
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• 2018

PURPOSES : The main purpose of this study is suggest of field bond strength evaluation method for more objective evaluation method through Evaluation of Bond Strength Properties with changing aspect ratio and temperature. METHODS : The evaluation is laboratory bond strength test. Using the core machine, the pull-off test method ; the bond strength test of interface layer the universal testing machine. RESULTS : As a result of the laboratory bond strength evaluation, it was verified that the bond strength by aspect ratio decreases linearly with increasing aspect ratio and the bond strength properties by temperature change existed at high and low temperature condition relative to odinary temperature condition. CONCLUSIONS : According to the results of laboratory bond strength evaluation, the field bond strength evaluation results suggest applying the proposed correction factor (0.8, 1.0, 1.4, 1.9) according to aspect ratio(0.5, 0.1, 1.5, 2.0), For more objective evaluation of the bond strength, it is analyzed that the evaluation value is within $6{\sim}32^{\circ}C$ and the result can be obtained within 5% of the coefficient of variation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.9-15
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• 2010

This paper analyzed the problems of the Korean output regulation in the relevant band through an analytic comparison of the current trend of each country and their standard values concerning electric field strength (technical standard) of weak wireless stations with less than 135kHz. In connection with the standard value of electric field strength of each country, which has been proposed in the registration of the appropriate electric wave, the paper aims to propose the standard value of electric field strength that could actually be introduced for suitable unauthorized wireless devices (weak wireless devices) in Korea. Provided that the Korean standard may be upgraded based on the tolerances of electric field strength proposed m this paper, this is expected to be committed to the distribution and advancement of weak wireless devices; and further it is anticipated to be prepared with competitiveness not only in the Korean communications market, but also in the international communications market.

• Journal of the Korea Society of Computer and Information
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• v.26 no.7
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• pp.103-108
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• 2021

In this paper, we an empirical study of the effects of control types on Tie strength and filed project performance of project participants in field project organization for Korean domestic construction industry. In the study, we try to tell what significant impact output control, process control and tie strength among field project participants have on field project performance and features unique to field project organization for Korean construction industry through empirical analysis. And the findings of the empirical analysis are that output control appeared to have significant impacts on tie strength among the participants and process control, and process control also appear to have significant impact on field project performance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.23-26
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• 2003

This study is intended to investigate the properties of early strength development by application of TEA to the field. According to the results, when TEA is added, fluidity is almost same to base concrete, and increases upto aimed slump after field flowing. Setting time does not differ in the case of base and TEA, but retarded after flowing. The time when compressive strength gains 5 MPa, which side form can be removed, is 23 hours, and so the removal time is shortened by I hours in comparison with plain concrete. But compressive strength is almost same to that of plain concrete at 28 days. The rebound value of P type schmidt hammer show similar tendency to compressive strength, and the rebound value of structure is higher than that of standard curing specimen due to heat capacity effect and drying by the air outside. Therefore, it is thought that if the rebound value of P type schmidt hammer is controled. by about 26 in consideration of open air environment, it is very effective to determine the removal time of side forms.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.23.1-26
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• 2003

This study is intended to investigate the properties of early strength development by application of TEA to the field. According to the results, when TEA is added, fluidity is almost same to base concrete, and increases upto aimed slump after field flowing. Setting time does not differ in the case of base and TEA, but is retarded after flowing. The time when compressive strength gains 5 MPa, which side form can be removed, is 23 hours, and so the removal time is shortened by 1hours in comparison with plain concrete. But compressive strength is almost same to that of plain concrete at 28 days. The rebound value of P type schmidt hammer show similar tendency to compressive strength, and the rebound value of structure is higher than that of standard curing specimen due to heat capacity effect and drying by the air outside. Therefore, it is thought that if the rebound value of P type schmidt hammer is controled. by about 26 in consideration of open air environment, it is very effective to determine the removal time of side forms.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.78-83
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• 2003

Electro-rheological(ER) fluids are suspensions in which rheological properties show an abrupt change with variation of electric fields. We modeled the parallel-plates relating to ER-Valve system and yielded shear stress according to the strength of electric field. The purpose of the present study is to examine the flow characteristics of ER fluids according to the strength of electric field between parallel-plates. Then the steady relationship between pressure drop and flow rate of the ER fluids between parallel-plates under application of an electric fields was measured. The pressure drop and flow rates of ER fluids under the application of electric fields for steady flow were measured. For the experiment, we used the ER fluids, 35w% zeolite having hydrous particles and differential pressure gauge. This test reviewed experiment for the special changes of ER fluids in the steady flow condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.470-474
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• 1997

Since the ceramic/metal joints is joined at high temperature, the residual stress will develop during when cooled from bonding temperature due to remarkable difference of thermal expansion coefficient between creamic and metal. Moreover, the edge of jointed interface makes singular stress field in the ceramic/metal joints and this singular stress field much influences on the strength of joints. In this study, The influence of residual stress, mechanical load and repeat thermal sysle was estimated in the ceramic/metal joints. According to this influence, the change of singular stress field was analyed and then strength test, X-ray measurement are performed.

• Advances in concrete construction
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• v.5 no.2
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• pp.87-99
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• 2017

After passing through a magnetic field, the physical quality of water improves, and magnetic water (MW) is produced. There are many investigations on the effects of magnetic field on water that shows MW properties like saturation and memory effect. This study investigates the fresh and hardened properties of concrete mixed with MW, which contains silica fume (SF) and superplasticizer (SP). The test variables included the magnetic field intensity for producing MW (three kinds of water), SF content replaced cement (0 and 10 percent), water-to-cementitious materials ratio (W/CM=0.25, 0.35 and 0.45) and curing time (7, 28 and 90 days). The results of this study show that MW had a positive impact on the workability and compressive strength of concrete. By rising the intensity of the magnetic field which was used for producing MW, its positive influence on both workability and compressive strength improved. MW had greater positive impacts on samples containing SP that did not have SF. Moreover, the best compressive strength improvements of concrete achieved as W/CM ratio decreased.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.230-237
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• 2001

For the structural integrity of large and complex structures such as railway vehicle, the in-field diagnosis of mechanical properties of the structures is needed, and especially, the mechanical characteristics of the weldment must be carefully evaluated. But, conventional standard testing methods having destructive procedures are not applicable to in-field assessment of mechanical property variations within weldment because they needs the limitations of specimen size and geometry. In this paper, to overcome this problems, the advanced indentation technique (AIS) is introduced for simple and non-destructive/in-field testing of weldment of industrial structures. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. First of all, flow properties such as yield strength, tensile strength and work hardening index can be evaluated through the analysis of the deformation behavior beneath the spherical indenter. Additionally, case studies of advanced indentation techniques are introduced.

• Journal of Korean Elementary Science Education
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• v.23 no.2
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• pp.141-151
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• 2004

Pre-service teachers' understandings on magnet was investigated through the questionnaire method. The questionnaire was composed of 17 questions about the strength of magnet, the magnetized object and the direction of magnetic field around magnet. In this investigation study, 225 pre-service teachers were selected through random sampling method, who were sophomores in a National University of Education. The formation rate of the scientific conceptions on the strength of magnet was 30.3% and that on the direction of magnetic field around magnet was 53.9%. The average formation rate of scientific conception of all questions on magnet was 44.13%, which doesn't seem to be high as expected. It shows that many of subjects of the questionnaire don't understand fully the concept of moleclar magnet model and the superposition effects of magnetic field around magnet. The formation rate of the scientific conception on magnet of females who took courses in sciences in high school were higher than that of females who took courses in arts in high school, which had meaningful difference (p<.05).