• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.209-217
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• 2002

The effects on structures caused by the replacement of the bridge bearings are investigated in this study. The bearings of the bridge are seriously deteriorated because of the breakage of lower concrete and the corrosion of the bearing itself. Also, the negative reaction states are created at some bearings on the abutment. Then, the bridge has occurred excessive vibrations and severe noise and impact whenever heavy trucks pass the above joints. The existing bearings are replaced using the adjustable bearing. The height of the bearings is adjusted to minimize the level difference of above joint and also to induce the appropriate distribution of live loads The effects of replacing the bearings are investigated by measuring the behaviors of the bridge without and with replacing works. The results without replacing the bearing show that the distribution of displacements and stresses is distorted in comparison with the analytical results. Also the bridge without replacing the bearing shows that the impact and vibration from the heavy trucks are larger than those with replacing the bearing. Load carrying capacity of the bridge increase about 1.8 times through replacing the bearing. The above results show that the structural performance of the bridge is improved by replacing only bridge bearings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.106-114
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• 2006

Uses of geosynthetics as a reinforcing material for earth structures have ever increased due to their excellent economy. fine external appearance. and easy construction. In the current practice of geosynthetics. however, the lacks of the standardized method of evaluating the soil/geosynthetics friction properties and the inconsistency of conventional design methods develop confusion to the civil engineers. The purpose of site monitoring of the retaining wall reinforced by geogrids was to evaluate the applicability of existing design methods to, and performance of. CHAMSTONE wall system. Full scale field performance during and after construction was monitored by incorporating instrumentation including strain gauges on the geogrid and soil pressure cells. The difference of the reinforcing effects of geosynthetics embedded in the soil will be also investigated by comparing of the line and curve types of retaining wall reinforced by geogrids with block type facings.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.27-32
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• 2018

Nowadays, to prevent electrical accidents in Korea, inspectors directly performed checking general electrical facilities as a cycle from every one to three years. It is difficult to presuppose an omen because intact conditions of electrical equipments are not kept at the time of inspection. In this paper, in order to ensure effectiveness of an online basis electric inspection, we developed an electrical safety IoT system using LoRa communication technology to enable monitoring mainly electrical safety components such as overcurrent, overvoltage, resistive leakage current, and power. Then we proposed a method for verifying performances of the prosed electrical safety IoT system. Resistive leakage currents are calculated by using difference of phase between voltages and currents. We verified that average errors are 0.97%, which reference goal is ${\pm}5%$ for a device, through reliability test according to conditions. Results of this research can be used as basic study materials to develop technologies for measuring three phase leakage current and for implementing public electrical safety. platform.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.206-217
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• 2001

The purpose of this study was to estimate that the relations of weathering speed and shear strength of granite soil by tracing the weathering depth of granite soil from the very moment of its cutting. The results obtained this follows ; 1) The relationships among Nc, Li and CEC, Li>6%, CEC>14 corresponds to Nc=2~30, and 4%${\phi}$)increases at a standard pressure. 3) And Nc=0~50 corresponds to $27{\sim}50^{\circ}$ of internal fiction angle and to 12~49kPa of cohesion. That is to say, internal friction angle(${\phi}$)corresponds better than cohesion(c). In conclusion, this study suggests that in simplified dynamic cone penetration test a penetration boundary line of 5 centimeters is decided at around Li=4%, CEC=3(meq/100g) which is classified as a completely weathering soil. It also appears that CEC increases as Li increases while Nc decreases.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.193-194
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• 2017

In this research, the density value of the turbid solution is measured by using the principle of inexpensive but easy Hydrometer method for cement delivered to the actual raw concrete plant, By analyzing the correlation of powder aid, we will try to present a scheme that can be utilized as a method of acquisition acquisition inspection. As a result of the analysis, it was found that there was a large difference between the measured powders assisted with cement powder on the report, and the correlation with the actually measured powder aid Hydrometer density value was good. Therefore, using the method of Fig. 3, it was possible to know that the degree of powder quality of cement delivered to the raw concrete factory can be evaluated quickly and utilized at the time of argument inspection.

• Journal of Sensor Science and Technology
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• v.17 no.5
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• pp.338-345
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• 2008

Steel bearing balls are important component in machines having moving parts. In this paper we describe a vision-based automatic inspection system designed for sensing defects on the surface of steel bearing balls. The system has a camera looking down over a rail on which balls roll. Two mirrors are installed at both sides of the rail so that the side parts of a ball can be well inspected. The entire ball surface can be sufficiently seen by taking three images at $120^{\circ}$ rotation interval. Defects are detected by thresholding the difference image between an image captured and the reference image of a good ball.

• Journal of Navigation and Port Research
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• v.38 no.2
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• pp.141-146
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• 2014

NIR(New Inspection Regime, hereinafter NIR) relating to the PSC(Port State Contorl, hereinafter PSC) has implemented in Asia-Pacific region under Tokyo-MOU from last January 2014. The most noticable difference between NIR and existing TF(Target Factor, hereinafter TF) is to evaluate company performance and to conduct PSC with flexible inspection interval on the basis of Ship Risk Profile; High Risk Ship, Standard Risk Ship and Low Risk Ship. Particularly deficiencies related to ISM Code, more than 5 deficiencies and detention record have a serious effect on the evaluation of Ship Risk Profile. Therefore ship and company are requested to ensure proper implementation of Safety Management System for the changed PSC tendency. Also RO(Recognized Organization, hereinafter RO) and Administration respectively should take suitable actions different to previous measures, such as implementation of cooperation and support system between vessel and company, changing subject and object for avoiding Mannerism in SMS audit, strengthening supervision on RO by Administration and establishment of private-public Partnership network.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.135-140
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• 2005

In case of rock bolt useable by tunnel reinforcement methods at field is applied problem of typical rock bolt pull test diagram method propositional in documents and is not thesis of clearness analysis basis about result of rock bolt pull test. So this paper suggested in consideration of foreign basis and field condition that the first, "suggestion of apposite diagram method at tight ground and difference application of rock bolt pull test method at loose and tight ground" and the second, "thesis of estimation basis non-thesis of design and specification, test etc".

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.147-157
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• 2005

In this study, consolidation analysis methods reflecting various ground condition and changing coefficient of consolidation with consolidation process are presented. Research activities include development of numerical program consists of two parts considering vertical drainage only and both drainage condition with vertical and radial direction. Also, interface equation of adjacent two layers and function for changing coefficient of consolidation are added to developed program. This paper presents the results from a detailed consolidation analyses, which explores consolidation process with time in varying layered system and changing coefficient of consolidation

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.4
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• pp.169-176
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• 2001

This study aims to present a more reasonable control value than the exiting one by comparing and analyzing control values and field instrument8tion values of the whole excavation depth of the four case sites, using geometric averaging as a statistical method. The range of the study is confined to the horizontal displacement of braced excavation walls among a variety of items, prescribed in the control values by approximately of the allowable and design values, and by safety factors. As a result, it is desirable to revise 70, 90, and 100 percent of LEVEL I, II, and III, respectively. The horizontal displacement values of the allowable and design values approximations should change to 104, 133, and 148 percent of the allowable and design values, respectively. In addition, modifying the horizontal displacement control value of the braced excavation walls is not needed. The horizontal displacement value, presented in the control value as a safety factor, is now 1.19, as it has a slight difference from the present value.