• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.629-634
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• 2007

The Alternative energy has lately attracted considerable attention due to the high oil price and environment problem. In this study, field test of facility for using the geothermal energy source from water-purifying device was constructed and monitoring devices are installed to estimate the efficiency of this system. Initial installation cost can be saved efficiently by connecting a heat pump system into the existing pumping well in site of water-purifying in Cheongju. One set of monitoring results during summer was presented and analyzed.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.603-606
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• 2000

The cost needed for the construction and management of highways in the whole nation is rapidly growing so the research that can decrease the cost is required. However, most of the highway specs have simply converted from those of other countries, including USA. Therefore, some of our design and construction specs were not the optimum ones based on our own situation, requiring a research under the actual traffic and environment of our nation. The use of test road develops many aspects of highway engineering. Those are evaluation of construction materials, a general overview of korea pavement design and serviceability under the actual traffic and environmental condition of the nation. It is also economical and efficient compared to the trial construction of each item in spreaded form. A test road, 7.7km long with two lanes, is being constructed on the Inner Central Expressway. In this test road, 2.7km is planned for asphalt pavement and 3.4km is planned for concrete pavement. Three test bridges and five earth retaining structures will be included in the test road. Based on the master plan, the major performance was progressing such as detailed research modules of each area, preliminary research for the future research, sensor surveys for the behavior analyses of pavements and structures with installation methods and data acquisition systems, the foundation research of Integrated Instrumentation System and the Management Plan for automated measurement. Some area(structure research division, geotechnical research division) was designed the instrumentation plan because some instrument sensors must be installed during the construction of the test road. And then the instrumentation plan of each area was enforcing because a large majority of the instrument sensors must be installed after the construction of the test road. The field surveys with material property tests and pilot instrumentation test with sensor tests was also performing in accordance with the construction in the field.

• Journal of the Korean Geotechnical Society
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• v.36 no.10
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• pp.5-19
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• 2020

With increasing demand for offshore structures, the demand for temporary structures to help the offshore construction work has increased. A cofferdam is a temporary barrier to stop the inflow of water in the construction site and allows working in the dry condition when the construction is done within the water. However, it is a major cause of construction delays and increased costs because additional works are required to block the water inflow. Recently, in order to overcome the limitations of the conventional cofferdam methods and to increase economic efficiency, a large-diameter steel cofferdam method has been proposed which can be installed quickly in the seabed by using the suction pressure. In this circular steel cofferdam method, the top side of the cofferdam including the top-lid is always exposed above the sea level in order to use it as a water barrier, unlike the conventional suction bucket foundation. After installation, the top-lid of the cofferdam is removed and the water filled inside the cofferdam is discharged to make the interior dry condition. In this study, the circular steel cofferdam with a 5 m inner diameter was fabricated and the installation tests were conducted at the Saemaguem test site. During the experiment, variation of suction pressure, leakage between connections, structure deformation, and inclination of the steel cofferdam were measured and post-analyzed. This study verified the new circular steel cofferdam method and confirmed that the suction installation method can be successfully used for various purposes on offshore structures.

• Journal of the Korean Geosynthetics Society
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• v.9 no.4
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• pp.75-84
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• 2010

In this study, the long-term performance tests, which have extensibility, creep deformation, installation resistance and durability characteristic, is conducted to apply geosynthetic strip in field. The strength reduction factors using the test results are evaluated in order to calculate long-term design tensile strength. First, the creep deformation was evaluated by both the stepped isothermal method(SIM) and the time-temperature superposition(TTS) method. The creep reduction factor is reasonable to apply 1.6. Second, the result of installation damage test had little damage of yarn, which affected strength of reinforcement. Therefore, it can be analyzed that the installation damage of geosynthetic strip has little effect of long-term design tensile strength. Finally, the durability reduction factor considering chemical, biological and outdoor exposure resistance is reasonable to apply 1.1, which is considered the stability and economic efficiency of reinforced earth wall using geosynthetic strip.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.4
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• pp.18-29
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• 2015

The purposes of this research and development are as follows: first, to provide pleasant driving environments inside tunnels; second, to improve the current illumination environments lacking in diffusion luminance meters to meet tunnel lighting standards; and, third, to reduce the consumption of tunnel lighting energy accounting for approximately 65% of tunnel maintenance costs because of inadequate visual environments and tunnel operations. Further details are listed below. Firstly, an image luminance meter for tunnels that can implement the L20-method which is a tunnel luminance method that follows the international standards of CIE88, which was developed in order to improve and change the existing illumination-based tunnel lighting operation system to a luminance-based system. (The margin of error of below 5% according to the results of a test by an authorized agency and field test). Secondly, early illumination control is possible since the lighting control system that can be operated based on luminance enables interlocking control of the inside and outside of a tunnel using ethernet communication. Thirdly, guidelines for field application of the system are proposed. In addition, the luminance inducers of tunnels are found and the reflexibility of each facility that may reduce luminance of the boundaries is also proposed. Fourthly, as a result of a test bed, power consumption of luminance-based lighting operations decreased by 15.6% compared to illumination-based operations. Applying the feedback controls and maintenance factors of internal/external luminance meters, it reduced by 36.4%. Therefore, we became able to provide a luminance-based lighting operation system that complies with tunnel lighting design standards and provides a visual environment for drivers.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.125-130
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• 2007

Single-phase is used widely power of field of appliance because can use commercialized power directly without power transform. Specially, because condenser nu-drive style single-phase induction motor efficiency is excellent, and most suitable in embodiment as economical. It is established true that method by crossing self-discipline and method by revolving magnetic field are interpretation of net single-phase induction motor, but method to calculate electric motor inside proper move in existent theory or method is some complex. That arbor in the law of circuit constant that combine equivalent circuit law with numerical analysis law according to development of the latest computer or microprocessor is suggested and does the calculation processing fast and correct. In this paper, measurement wishes to present method that calculate after calculate digital measurement that measures correctly and measures impossible the first and the second leakage reactance and no-load test locked-rotor test, DC test and resistance measurement of stator winding in circuit parameter calculation program that is had for MatLab program individually in single-phase power.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.10
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• pp.141-149
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• 2007

This paper introduce to improve the reliability of the expected service life and the insulation condition evaluation of the high voltage induction motors by assessing, comparing and analyzing the correlation between the dielectric properties of the off-line insulation diagnostic test and dielectric strength on the insulation breakdown test. The insulation diagnostic tests include insulation resistance, polarization index(P.I.), dissipation factor($tan{\delta}$), maximum partial discharges($Q_{max}$) and AC breakdown test. This study evaluated the correlation between insulation diagnostic test and AC breakdown test for stator winding of high voltage induction motor. On the basis of these test results, we expect that this study can be used for effectively assessing the results of insulation diagnostic tests for similar class induction motors in service at industrial field.

• International Journal of Highway Engineering
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• v.20 no.4
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• pp.7-13
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• 2018

PURPOSES : In order to apply high-speed weigh-in-motion (HS WIM) systems to asphalt pavement, three high-durability asphalt concrete mixtures installed with a WIM epoxy are evaluated. METHODS : In this study, dynamic stability, number of loading repetitions to reach the rut depth of 1 mm, and rut depth measurements of three asphalt mixtures at $60^{\circ}C$ were compared using an Asphalt Pavement Analyzer (APA). Laboratory-fabricated material and field core samples were prepared and tested according to KS F2374. RESULTS : Through the laboratory tests, it was found that all three modified asphalt mixtures (stone-mastic, porous, and semi-rigid) with WIM epoxy showed favorable permanent deformation results and passed the dynamic stability criterion of 3000 loading repetitions per 1 mm. In addition, it was confirmed that the modified SMA mixtures cored from the field construction yields satisfactory rutting testing results using the APA. Finally, the epoxy used for the HS WIM installation shows good adhesion with the three asphalt mixtures and permanent deformation resistance.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.439-444
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• 2007

Using the anaerobic digester gas as a fuel, fuel cells have the potential to provide significant environmental and economic benefits. A molten carbonate fuel cell power plant was installed in the municipal sewage works of Tancheon in Seoul. The fuel cell unit operates on anaerobic digester gas and provides power and heat for the sewage works. This is the first project of its kind in Korea. This article outlines the experiences of gas purification process with planning, installation and operation. The engineering and installation phase is described regarding to the special features of digester gas, for example impurities in gas composition. Such impurities would be harmful to fuel cells. Operational results from the field test with a gas purification process plant are presented in this paper.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.9
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• pp.32-39
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• 2006

In this paper, an iterative subspace-based calibration algorithm for a CDMA-based antenna array in the presence of unknown gain and phase error is presented. The algorithm does not depend on the array geometry and does not require a prior knowledge of the Directions Of Arrival (DOA) of the signals. The method requires the code sequence of a reference user only. The proposed algorithm is based on the subspace method and root finding approach, and it provides estimates of the calibration vector, the DOA and the channel impulse response, by using the code sequence of a reference user. The performance of the proposed algorithm was investigated by means of computer simulations and was verified using field data measured through a custom-built W-CDMA test-bed. The data show that experimental results match well with the theoretical calibration algorithm. Also, teh study propose an efficient algorithm using the simulated annealing technique. This algorithm overcomes the requirement of initial guessing in the subspace-based approach.