• Journal of Ocean Engineering and Technology
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• v.29 no.2
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• pp.169-174
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• 2015

This paper addresses experimental methodologies to measure the temperature-dependent thermal conductivity of the insulation materials popularly used for LNG cargo containment systems. The measurement techniques considered in this paper are the guarded hot plate (GHP) method and heat flow method (HFM). The former is based on the power supplied to the hot plate to keep the temperature constant, and the latter is based on a direct heat flux measurement. In order to improve the accuracy of the HFM, the thermal conductivity obtained by GHP was cross-compared with the HFM results, and a calibration factor was derived. It was found that the thermal conductivities measured by the two methods corresponded well under room temperature, but the deviation tended to slightly increase as the temperature decreased. Because of the easy installation and operability of HFM, it can be used to measure thermal conductivity in a large scale mock-up test or unit insulation panel test, where the GHP method is difficult to apply.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.62-69
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• 2010

Many electric poles in the softground have been collapsed due to external load. In this study, 10 types of tests were performed with variation of location, numbers and depths of anchor blocks as well as depth of poles to find horizontal earth pressure through full scale pull-out tests. The horizontal earth pressure increased with embedded depth of electric pole, and earth pressure of lower passive zone decreased. The deeper of anchor block, earth pressure of passive zone becomes less. 4 anchor blocks decreased earth pressure at G.L.-0.9[m]. It is considered that 4 anchor blocks installed along 80[cm] vertically are main reason. Overall, when more anchor blocks are constructed, excavation area is large, and constructivity such as backfill is bad, therefore one anchor block would be preferred.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.1
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• pp.19-29
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• 2023

An ultra-high strength prestressed prismatic beam of 100 MPa in compressive strength was developed by increasing the watertightness of concrete by utilizing centrifugal molding processes without adding expensive admixtures such as silica fume. The ultra-high strength centrifugal shaped square beam installed on the wall is composited with the upper slab concrete and then subjected to a service load. Horizontal shear stress is generated by bending between the centrifugal molding beam and the floor plate, which causes the beam and floor plate to perform composite behavior through shear connections such as studs and rebars. In this study, a flexural load test was performed on a mock-up specimen that was synthesized by fabricating an RC slab on top of a 100 MPa-class centrifugal shaped beam produced at the factory. proven reliability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.128-135
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• 2010

Polymer-modified cement mortar(PCM) has been widely used for strengthening of the concrete structures due to its excellent physical properties such as high strength and durability. Adhesive strength or behavior, on the other hands, between PCM and concrete is very important in strengthening the concrete member using PCM. Therefore the adhesive failure mechanism between PCM and concrete should be fully verified and understood. This study was performed to evaluate adhesive strength of PCM to the concrete by the direct pull-out test. In the direct pull-out tests, the adhesive strength under the various pre-treatment conditions such as immersion, thunder shower, freezing and thawing are evaluated. Also, the field direct pull-out test are performed to investigate the adhesive strength of mock-up test specimens. In the results of the test, the adhesive strength value by field test are lower than those of the standard curing condition. From these comparison and investigation, field test result was similar with the thunder shower test result. The results of the test was used to evaluate the korean industrial standard of polymer modified cement mortars for maintenance in concrete.

• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.517-528
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• 2013

The modular technology has been already applied in automotive industry, plant and shipbuilding industry. Recently, the modular technology was applied in bridge construction. The modular bridge is different from the existing precast bridges in terms of standardized design that the detailed design of members is omitted by using the standard modules; the design of the modular bridge is completed by only assembling the standard modules without design in member level. The girder-type precast modular bridge has been developed as a simply supported bridge. The girder-type precast modular bridge could be applied to the multi-span bridges through the continuity method. The continuity of the girder-type precast modular bridge is achieved by using the link slab which is easy to construction and appropriate to the rapid construction. The link slabs have been used as the type of reinforced concrete structure in US from the 1950's. In 2000's, the link slab using the engineered cementitious concrete (ECC link slab) has been developed. In this study, the RC type link slab which is more reproducible and economic relative to the ECC link slab was used for the continuity of the girder-type precast modular bridges, and the construction detail of RC type link slab was modified. In addition, the modified iterative design method of RC type link slab was proposed in this study. To verify the proposed design method, the flexural tests were conducted using the RC type link slab specimens. Also, the fatigue test using the mock-up specimen was conducted with cyclic loading condition up to two million cycles.

• Journal of the Korea Institute of Building Construction
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• v.16 no.3
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• pp.229-235
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• 2016

In construction field, it used various technique for concrete formwork. Part of them, non-destructive test has been conducted to estimate a compressive strength of concrete easily such as rebound method and ultrasonic pulse velocity method etc. Former research has recommend proposed equation based on experimental data to investigate strength of concrete but it was sometimes deferent actual value of that from in field because of the few of data in case of early strength concrete. In this study, an experiment was conducted to analyze strength properties for early strength concrete using cylinder mold and $1,000mm{\times}1,000mm{\times}200mm$ rectangular specimen. And compressive strength of concrete was tested by non-destructive test, and calculated by the equation proposed former research. As a result, the non-destructive test results showed approximately 70 percent of the failure test value for all conditions, and worse reliability was obtained for high strength concrete samples when the ultrasonic pulse velocity method was used. Based on the scope of this study, the experimental equation for estimating compressive strength of early strength concrete from 24MPa to 60MPa was proposed.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.485-497
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• 2012

Recently, with increasing social interests on noise and vibration induced by railway traffic, the application of floating slab track that can efficiently reduce the railway vibration is increasing. In this study, to more accurately understand the dynamic behavior of the floating slab track, a laboratory mock-up test has been performed, and the static and dynamic behaviors at frequency range near the system resonance frequency were explored. Based on the test results, the design of the floating slab track and the structural analysis model used in the design have been verified. The analytic and test results demonstrate that the dominant frequency of the floating slab track occurs at the frequencies between vertical rigid body mode natural frequency and bending mode natural frequency, and the dominant deformation mode is close to the bending mode. This suggests that in the design of the floating slab track, the bending rigidity of the slab and the boundary conditions at slab joints and slab ends should be taken into consideration. Also, the analytic results by the two-dimensional finite element analysis model using Kelvin-Voigt model, such as static and dynamic deflections and force transmissibility, are found in good agreement with the test results, and thus the model used in this study has shown the reliability suitable to be utilized in the design of the floating slab track.

• Journal of Welding and Joining
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• v.20 no.2
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• pp.82-89
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• 2002

In order to clarify hot cracking phenomena occurred in Inconel 690 welds and it's prevention, in this study, the cracking behavior and the influence of welding variables on cracking in Inconel 690 overlay welds on Mn-Ni-Cr-Mo steel(SA 508 cl.3) for pressure vessel were investigated by using mock-up test. The main results are as follows: The cracks in Inconel 690 overlay welds were mainly generated near the start and the end part of welding beads adjacent to STS 309L welded outside of Inconel 690 welds. Most of the cracks showed typical solidification crack, and also it was assumed that there was possibility of liquation cracking in HAZ. The existence of Nb constituents or concentration of Nb was recognized on the fracture facets of the solidification cracks in the welds by SMAW. Therefore Nb was considered to be the main factor of the solidification cracking. As the weld heat input was more increased and the weld bead length was longer, the extent of cracking was more increased. Moreover the extent of cracking was considerably decreased by changing of welding sequence to the start and the end part of welds. Hot cracking in welds by GTAW was considerably decreased as compared with that of SMAW. And cracks were well generated in the Inconel 690 overlay welds adjacent to 575 309L welds. This means that the hot cracking susceptibility of Inconel 690 welds was largely varied by chemical components and/or compositions of filter metals, base metals and neighboring welds.

• Journal of Chest Surgery
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• v.28 no.6
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• pp.542-548
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• 1995

The goal of this study is to develop an effective control system for cardiac output regulation based upon the preload and afterload conditions without any transducers and compliance chambers in the moving actuator type total artificial heart. Motor current waveforms during the actuator movement are used as an input to the automatic control algorithm. While the current waveform analysis is performed, the stroke length and velocity of the actuator are gradually increased up to the maximum pump output level. If the diastolic filling rate of either right or left pump begins to exceed the venous return, atrial collapse will occur. Since the diastolic suction acts as a load to the motor, this critical condition can be detected by analyzing the motor current waveforms. Every time this detection criterion is met, the control algorithm decreases the stroke velocity and length of the actuator step by step just below the critical detection level. Then, they start to increase. In this way the maximum pump output under given venous return can be achieved. Additionally the control algorithm provides some degree of afterload sensitivity. If the aortic pressure is detected to exceed 120 mmHg, the stroke length and velocity decrease in the same way as the response to the preload. Left-right pump output balance is maintained by proper adjustment of the asymmetry of the stroke angle. In the mock circulatory test, this control system worked well and there was a considerable range of stroke volume difference with adjustment of the asymmetry value. Two ovine experiments were performed. It was confirmed that the required cardiac output regulation according to the venous return could be achieved with adequate detection of diastolic function, at least in the in vivo short-term survival cases[2-3 days . We conclude that this control algorithm is a promising method to regulate cardiac output in the moving actuator type total artificial heart.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.129-135
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• 2010

The purpose of this research is to secure fundamental data on the application of fibre as a fire resistance method for more than 60 MPa high-strength concrete through an examination of mechanical properties and fire resistance performance. The results are as follows: 1) When there are less than 0.5~1.0kg/$m^3$ contents of PP and NY fibre for 60MPa and less high strength concrete, 1.0kg/$m^3$ contents of PP and NY fibre for less than 80MPa high strength concrete and 1.5kg/$m^3$ contents of NY fibre for more than 80MPa high strength concrete, the effect of fibre contents on workability and strength development is not significant. 2) Based on the result of a 3-hour fire resistance test for mock-up column, it is necessary to secure 50 mm of covering depth for the regulation of fire resistance performance of high strength concrete to the standards of The Ministry of Land, Transport and Maritime Affairs. 3) It is necessary to secure more than 400mm of column size for stable fire resistance performance.