• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.162-170
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• 2010

The torque-coefficient of torque-shear type high-strength bolts is affected by the environmental factors, such as 'wet', 'rust', 'exposure to air' and workability during tightening high strength bolts. It is difficult to assume the direct tension induced into the bolt due to variation of torque-coefficient for torque-shear type high-strength bolts. Therefore, it is essential to measure tension loads of bolts and to verify the clamping force under construction. In this study, the manufacture of trial product was planned to identify the induced force into the bolts. The algorithm for a trial product was composed of the relation between electricity energy taken from torque shear wrench and tension force from hydraulic tension meter. The regression analysis equation to measure the direct tension was derived by statistical analysis using Minitab program. It is considered that the trial product is reliable tool to evaluate the tension force comparable to a commercial torque wrench.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.476-481
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• 2009

Bi-directional load test is one of O-cell tests. The O-cell test is a system which may be used for performing static load tests on cast in situ reinforced concrete bored piles. The technique was devised and developed by Osterberg of Northwestern University(USA) and has been in use around the world. The principle of the method is that an O-cell is installed in a cast in situ bored pile base. Once the pile concrete reaches its design strength the cell is connected to an hydraulic pump and pressured. Pressurization causes the cell to expand, developing an upward force on the section of pile above the cell loads, pile movements and strains within the pile then enable the capacity of the pile and its load settlement curves to be ascertained. The O-cell pile load test with variable end plate is operated on second steps - the first step is to confirming end bearing capacity with variable end plate and the second step is similar to the conventional O-cell test. In the study, To calculate ultimate capacity of bi-directional load test using model with the pile with variable end plate O-cell.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.108-118
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• 2009

As increasing demand on marine structures and skyscrapers, a deep shaft pile is frequently to be used for the place having weak ground strength. Because heavy horizontal force is generally applied on upper part of pile foundation used in engineering field, steel pile is highly used due to its high resistance to shear force and bending moment, and its capability to carry heavy loads. The steel pile has advantage in good constructibility, high applicability on site and easy handing, but has disadvantage in cost, more expensive than other material pile. This study is to examine the composite pile that makes economical construction possible by reducing material cost of pile; using steel and PHC pile A non welding connection method is applied to this composite pile. This study had step of comparison with the result of numerical analysis after analyzing the result of field test. Numerical analysis is the process of analyzing lateral behavior of non welding composite pile. Moreover, detailed analysis was implemented in order to evaluate joint stability. As a result of the analysis, we could interpret that the stability of the connection part is ensured as seeing the smaller internal stress than approved internal stress. Based on this study, we analyzed lateral behavior of non welding composite pile, which ensured the stability of connection part.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.119-126
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• 2015

The wall system has been also tending to shift from existing concrete wall to variable lightweight wall according to increasing use of column structure system in apartment construction. Therefore, wall needs certain amount of strength which also means the standard measurement of resistance against loading of wall attachments is needed. Nevertheless, there currently aren't enough researches of related standards for such measurement. For such reason, the research would be used as baseline data to development for test methods of load resistance about attachments on the lightweight wall, that presented improvements in the apparatus and maximum loads for domestic circumstances by researching current tests.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.555-560
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• 2003

Korean High Speed Train(KHST) has been tested on the high speed test line in Osung site of Korea High Speed Rail Construction Authority (KHRC). since it was developed as G7 Project Plan In 2002. This paper introduces the dynamic test devices in KHST and shows the comparison between the results of test and theoretical computing results which derive from the new model for KHST dynamic behavior. Previous computer simulation model for KHST was developed to review wether the vehicle system was satisfied with the dynamic performance requirements during the design procedure. But It should be applied the results of the parts test for suspension elements in order to compare between the results of computation and real test. Using VAMPIRE Program made by AEA Technology in UK. the new model also was modified. This paper shows that the static wheel loads calculated from new model is similar to test results. For test on high speed line, we prepared the test devices for evaluating the dynamic performances. which was consisted of the accelerometers( based on Kisler Co.) and the data aquisition systems (based on National instrument Co.), and test program coded by LabView 6i program. These lest devices and programs are flexible to extension the channels for adding sensors and connect to the ethernet network. The acceleration of car bodies, bogie frames and axle boxes were compared between the results of computation and test at 150km/. This paper shows that the results of test were high in high frequency band range but similar frequency band range. It might be considered that these differences were caused by the test which did not performed at constant speed for comparison analysis. Also. It will be able to understand the differences and make better results through a lot of tests planed in future.

• Geotechnical Engineering
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• v.11 no.2
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• pp.51-70
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• 1995

Types of foundation of high rise buildings are primarily determined by loads transmitted from super structure, soil bearing capacity and available construction technology, The use of deep foundation of the buildings considered in this study due to the fact that rock of enough bearing capacity is not found down until 90~l00m. When a concentration of high soil pressure must be distributed over the entire building area, when small soft soil areas must be bridged, and when compressible strata are located at a shallow depth, mat foundation may be useful in order to have settlement and differential settlement of variable soils be minimized. The concept of mat foundation will also demonstrate some difficulties of applications if the load bearing demand directly carried down to the load -bearing strata exceeds the load -bearing capacity. This paper introduces both the analysis and design of mat type foundation for high rise buildings as well as the method-ology of modelling of the soil foundation, especially, engineered to redistribute the stress exceeding the soil bearing capacity. This process will result in the wide spread of stresses over the entire building foundation.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.65-74
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• 2005

The negative skin friction on piles, which are installed in currently consolidating soft deposits, creates significant problems on the stability of pile foundations. This study investigated whether or not the pile foundation designs were appropriate in soft deposits with large amount of consolidation settlement. The final settlements of the grounds along the pile depth were estimated by the soil parameters obtained from the laboratory tests and by the field-measured settlement curves, if they were available. The displacement of the piles along the pile depth was estimated by both the load transfer method and the numerical method. Both methods gave similar locations of neutral planes and magnitudes of the maximum axial forces on the piles. The movements of the ground and the piles were compared to calculate the down drag acting on piles. For the piles whose bearing capacities were less than the design loads including the down drag, slip layer coatings and/or incrementing of the pile penetration depth into the bearing stratum were proposed to improve the pile capacities.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.49-56
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• 2012

The purpose of this paper is to present a model for operating an emergency power system(EPS) that can secure a sufficient power supply used in case of a fire by analyzing the status of power supplies for emergency and firefighting operations. Investigations on the one of the causes of the operational failure of firefighting systems show evidence of EPS. Generally, when power to a building is interrupted, EPS supplies the emergency load(excepted firefighting load) first. When a power outage and a fire occur simultaneously, the EPS must be able to supply both the emergency load and the firefighting load, especially the firefighting load to the end. However, in order to save construction costs, emergency power generators in apartment, commercial, and business buildings can satisfy only one of the required loads. In cases like this, when a power outage and a fire occur simultaneously, there is a danger of firefighting equipment not operating due to insufficient power supply from the emergency generator. Therefore, an EPS must have a reserved firefighting power that can supply both the firefighting and the emergency load. Such EPS, when faced with a danger of an overload, will shut down the supply to all or part of the emergency load, thus securing a continuous power supply to the firefighting equipment. The generator power system with reserved firefighting power (RFP) will also have an indicator to show that the selective control is being used. General power generation systems for emergency load and firefighting load were found to have a demand factor of 50-60% with a lump. However, when installing an EPS, the builders must choose the higher demand factor suggested according to the official approval demand factor of the building.

• Journal of Navigation and Port Research
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• v.36 no.5
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• pp.357-361
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• 2012

Anemometer is a meteorological instrument that measures wind direction and wind speed in real time, and is mounted to the cranes that are used at ports, shipbuilding yards, off-shore structure, or construction sites that are influenced by wind, and it is used in conjunction with the safety system. Load cell-type anemometer measures the wind direction through the ratio of load between 4 positions by mounting the thin plate to 4 load cells, and measures wind velocity through the summation of loads. In this study, we compared and analyzed the results in the theoretic approach, analytic approach and experimental approach to derive the correlation between load ratio and wind direction. Wind direction was selected as the design variable, and selected 9 wind direction conditions from $0^{\circ}{\sim}90^{\circ}$ with $11.25^{\circ}$ space for analysis, and 10 wind direction conditions with $10^{\circ}$ space for experiment.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.4
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• pp.195-198
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• 2000

This paper illustrates a new method for constructing composite power system effective load duration curve(CMELDC) at load points. The main concept of proposed method is that the CMELDC can be obtain from convolution integral processing of the outage probabilistic distribution function of not supplied power and the load duration curve given at each load point. The effective load duration curve (ELDC) at HLI plays an important part in probabilistic production simulation, reliability evaluation, outage cost assessment and power supply margins assesment for power system planning and operation. And also, the CMELDC at HLII will extend the application areas of outage cost assessment and reliability evaluation at each load point. The CMELDC at load points using the Monte Carlo method and a DC load flow constrained LP have already been developed by authors. The effective load concept at HLII, however, has not been introduced sufficiently in last paper although the concept is important. In this paper, the main concept of the effective load at HLII which is proposed in this study is defined in details as the summation of the original load and the probabilistic loads caused by the forced outage of generators and transmission lines at this load point. The outage capacity probabilistic distribution function at HLII can be obtained by combining the not supplied powers and the probabilities of the not supplied powers at this load point. It si also expected that the proposed CMELDC can be applied usefully to research areas such as reliability evaluation, probabilistic production cost simulation and analytical outage cost assessment, etc. at HLII in future. The characteristics and effectiveness of this methodology are illustrated by case study of IEEE-RTS.