• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1875-1881
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• 2007

Deformations of bridge deck ends on abutments or on transition between bridge decks can cause extreme deformations on track. Especially, since slab track is fixed onto the bridge deck slab on concrete slab track-installed bridges, deformations of bridge deck ends directly affect the track behavior, and thus these interactions can bring about the premature failure of rail fastenings or other deteriorations to lower the serviceability. In this study, a foreign standard to evaluate forces on track components caused by the track-bridge interactions and the serviceability of bridge deck ends is investigated, and for the real bridges, the serviceability of bridge deck ends according to several parameters of bridge and track is analyzed. It is found that arrangements and spring coefficients of bridge bearings, as well as distance between bridge bearing and last rail support, support spacings, rail support spring coefficient, are very important parameters.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.3
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• pp.29-36
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• 2000

The purpose of this study is to develop and adapt indicators for the rural community assessment. Bearing in mind, indicators are derived from the various theoretical literature review and the efficiency of the indicators has been tested through comparing and evaluating 3 different rural communities which was selected based on their distance from Seoul. In order to assess a rural development project, the assessment indicators should include at least 5 domains of natural environment, socio-economic, quality of living environment, community characteristics, public participation, which are the basic formation of indicators of this study. Furthermore, this approach could be a ground for the environmentally friendly rural development planning.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.47-57
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• 2000

Experimental and numerical studies were done to investigate seismic performance of slender shear walls with no boundary confinement that are principal structural members of high0rise bearing wall buildings. 1/3 scale specimens that model the plastic region of long slender shear walls subjected to combined axial load and bending moment were tested to investigate strength, ductility, capacity of energy dissipation, and strain distribution, The experimental results show that the slender shear walls fail due to early crushing in the compressive boundary, and then have very low ductility. The measured maximum compressive strain is 0.0021, much less than 0.004 being commonly used for estimation of ductility. This result indicates that the maximum compressive strain is not a fixed value but is affected by moment gradient along the shear wall height and distance from the neutral axis to the extreme compressive fiber.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.845-850
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• 2012

Currently power of the diesel engine is increasing continuously, where the wearing problems become more severe. The wearing happens irregularly inside the cylinder, which causes a high burden to the marine engine. In this paper, a novel scheme to measure the wearing and to represent the engine states has been proposed. To monitoring the states of the marine engine efficiently, a laser displacement sensor has been utilized to measure the wearing happening inside the marine engine. To eliminate the noise signals in the distance measurement, the wavelet transform has been adopted, which is robust against the noises caused by vibrations. An engine simulator is designed to develop the system for measuring the engine wears, where the superiority of the wavelet transform against the conventional filtering schemes has been demonstrated.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.10a
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• pp.137-144
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• 1992

This paper reports a case study of dynamic consolidation. The objective of the study is to evaluate the effectiveness of ground improvement at the site for Hyundai Petrochemical Compound constructed at Daesan-Myeon, Seosan-Gun in the western shores of Korea. The site ground was prepared by filling on the existing soft marine deposit which consists of a loose granular soil layer and a medium stiff clay layer. For the stabilization of site ground, the compaction was executed in three different procedures with same pounder weigh, drop height and imprint spacing. The post investigation showed that the object was successfully achieved indicating a significant increase of bearing capacity of the treated ground. In this study the effectiveness of dynamic consolidation is evluated for various factors the applied energy, temping sequences, the radial distance from the imprint location and the depth of bed rock.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.453-458
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• 2003

When the piezoelectric extracorporeal shock wave lithotripter is operated. sounds are generated. In this paper, we present a fact that the sounds are radiated undoubtedly from the object to be hit by the shock waves. For this results. we use the method to identify the sound source location of the radiated sounds by estimating the distance and the bearing from the sound source using one hydrophone. In addition. we investigate the relation between the radiated sounds and the vibrations of the objects using bronze models of disc type with clear vibrating characteristics and present the results of experiments to be analyzed.

• Journal of the Korean Ceramic Society
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• v.34 no.8
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• pp.797-802
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• 1997

The use of carbon materials in mechanical components such as bearings, seals, and bushings that do not require lubricants is increasing rapidly. This paper reports on establishing the optimal condition for resin-bonded carbon materials. We fixed the content ratio of materials, which include graphite powder and diatomite as a lubricant modifier and a friction modifier, respectably, with resin used as a bonding material. We then produced bushings using hot-pressing within the temperature range of resin curing. The properties of bushing, the friction coefficient, wear rate and the mechanical strengths are discussed in relation to the content of respective materials, with correlation of friction coefficient and sliding distance. Finally, we examined the friction coefficient changes according to the applied load on bushing and the friction coefficient changes according to contact speed of bushing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.609-617
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• 2017

Railways are one of the safest and most important transportation systems in the world. On the other hand, due to the increasing complexity of the railway system and the running distance of rail vehicles, railway accidents occur continuously every year. In particular, in the case of high-speed trains and freight trains, if the function of the axle bearing is lost due to abnormal overheating of the axle box bearing, the load on the axle becomes uneven. Therefore, abnormal overheating in the train axle box bearings can cause serious accidents or derailments. For this purpose, a Hot Box Detector (HBD) was installed in the track side of a high speed line to detect abnormal overheating. This paper proposes an EWMA technique-based axle temperature monitoring method to detect abnormal overheating quickly and efficiently. A statistical design of the proposed method was also performed. The proposed method has better performance compared to the current method in the case of abnormal overheating and the performance is improved by approximately 170% at the maximum.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.95-103
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• 2009

Deformations of bridge deck ends on abutments and piers bring about severe problems in track geometry and require maintenance work. In case of concrete slab track, more severe deformation and additional forces on rail and rail supports can be induced by bridge deck deformation, which affect the serviceability of track structure since concrete slab track is much stiffer than ballasted track and the behavior of track structure is integrated with that of bridge deck. In this study, the design variables affecting the serviceability of track structure are selected and the influence level is estimated by a parametric study. As a result, it is found that continuous span is advantageous than simply supported span and the stiffness of bridge bearing and rail fastener as well as the distance between last rail support and bridge bearing are most important parameters.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.27-32
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• 2008

This paper describes a contact atomic force microscope (AFM) that can be used for high-speed precision measurements of microstructured surfaces. The AFM is composed of an air-bearing X stage, an air-bearing spindle with the axis of rotation in the Z direction, and an AFM probe unit. The traversing distance and maximum speed of the X stage are 300 mm and 400 mm/s, respectively. The spindle has the ability to hold a sample in a vacuum chuck with a maximum diameter of 130 mm and has a maximum rotation speed of 300 rpm. The bandwidth of the AFM probe unit in an open loop control circuit is more than 40 kHz. To achieve precision measurements of microstructured surfaces with slopes, a scanning strategy combining constant height measurements with a slope compensation technique is proposed. In this scanning strategy, the Z direction PZT actuator of the AFM probe unit is employed to compensate for the slope of the sample surface while the microstructures are scanned by the AFM probe at a constant height. The precision of such a scanning strategy is demonstrated by obtaining profile measurements of a microstructure surface at a series of scanning speeds ranging from 0.1 to 20.0 mm/s.