• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.2
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• pp.101-107
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• 2015

Field balancing is required in any kind of phase information for the determination location balancing mass toward a rotor unbalance mass. Phase or phase angle is a measurement of the relationship of how one vibration signal which relates to another vibration signal and is commonly used to calculate the placement of balance weight. In this paper, A right guideline shows the photo optical speed sensor as the external KeyPhasor is a very useful when diagnosing machinery vibration problems on considering a phase lag comparing to the laser optical speed sensor. Some experimental results generate the interesting phase errors when appling to a wrong conditions. So, Usage of photo optical speed sensor which is used primarily to measure the shaft rotating speed serves as a reference for measuring vibration phase information has effect on the placement of phase angle how it was misunderstood. This paper will help a right method to search for the position of balancing weight and serves as baseline for further measurements using low cost and much easier user convenience. It is concluded that the propose baseline is likely to be applicable to apply to the practical field balancing weight.

• 보존과학연구
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• s.33
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• pp.69-83
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• 2012

Field experiments for Conservation damage on selected spots were carried out prior to direct conservation treatments for Bangudae Petroglyphs in Ulsan. It was found that there is a big difference in treatment effects according to the treatment technique and application rather than on the treatment material use. Based on the results of this study, a plan for the conservation treatment of Bangudae Petroglyphs will be suggested by providing new materials and application techniques for cracks, adhesive application and consolidation by conducting artificial weathering tests and continued monitoring.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.10
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• pp.969-976
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• 2004

Building energy saving is one of the most important issues in these days. Energy saving control strategies should be developed properly to achieve the saving. One of such area we could apply is the HVAC (Heating, Ventilation and Air-Conditioning) system. Through the optimal control algorithm for building energy management system (EMS), you can not only save the cost of building energy, but also protect HVAC system components against the unexpected condition. In order to verify the effectiveness of building energy saving, field test was accomplished for several months at 'A' building. And to get the measured data, remote control was used. If the remote control is used in BAS (Building Automation System), control and monitoring can be done for all of the building systems, such as HVAC, power, lighting, security and fire-alarm etc. anywhere any time. Using the remote control, Control and monitoring is possible for the testing system without going there. As the results of field test, we could reduce $5{\sim}10\%$ of the building energy cost.

• Journal of Soil and Groundwater Environment
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• v.28 no.spc
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• pp.18-39
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• 2023

Rapid development of geophysical exploration and hydrogeologic monitoring techniques has yielded remarkable increase of datasets related to groundwater systems. Increased number of datasets contribute to understanding of general aquifer characteristics such as groundwater yield and flow, but understanding of complex heterogenous aquifers system is still a challenging task. Recently, applications of data science technique have become popular in the fields of geophysical explorations and monitoring, and such attempts are also extended in the groundwater field. This work reviewed current status and advancement in utilization of data science in groundwater field. The application of data science techniques facilitates effective and realistic analyses of aquifer system, and allows accurate prediction of aquifer system change in response to extreme climate events. Due to such benefits, data science techniques have become an effective tool to establish more sustainable groundwater management systems. It is expected that the techniques will further strengthen the theoretical framework in groundwater management to cope with upcoming challenges and limitations.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.71.3-72
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• 2021

The Intensive Monitoring Survey of Nearby Galaxies (IMSNG) is a high cadence observation program monitoring nearby galaxies at < 50 Mpc with high probabilities of hosting supernovae (SNe). The current number of main IMSNG targets is 60, but with new wide-field facilities joining IMSNG, there is a possibility of increasing the likelihood of catching the early light curves of SNe among galaxies in the vicinity of the main targets. To test the feasibility of the expansion of the sample galaxies, we examine how much the probability of catching SNe increases by adjusting the field of view of the RASA36 telescope which is one of the IMSNG facilities with a large field of view of 6.25 deg2. We calculate supernova rates (SNRs) of galaxies within the FoV that contains main IMSNG galaxies from the stellar mass and star formation rate of the galaxies. Based on the SNRs of these galaxies, we find the best pointing of the telescope towards the highest SNR region. As a result, we present improved total SNR, with respect to the ordinary pointing on average where the IMSNG main target is placed at the center of FoV. The actual observation should be followed to test the effect of this strategy.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1305-1312
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• 2006

This study is about the development of measurement system using ubiquitous wireless communication for river flow monitoring. The system can acquire water depth, quality (temperature, pH, conductivity, turbidity etc.) while a GPS module for getting the location data of measurement points. Also this system is able to acquire the field data via RF connection and can be controlled same time. The acquired data is transmitted to a gateway system from the remote buoy using Zigbee wireless connection. And the gateway system is able to monitor the data through GIS monitoring tool. Finally the data are transmitted to a server computer using CDMA wireless connection by gateway system. The D/B of server computer are constructed automatically and monitored the project web site. The resulting system can be used for scour monitoring, environment monitoring and the other monitoring purposes such as a river flow monitoring system.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.22 no.6
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• pp.63-76
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• 2019

UAVs are unmanned, autonomous or remotely piloted aircraft. As UAVs become smaller, lighter and more economical, their applications continue to expand. Researches on UAVs in the field of remote sensing show development methods and purposes similar to those on satellite images, and they are widely used in studies such as 3D image composition and monitoring. In the field of environmental impact assessment(EIA), satellite information and data are mainly used. However, only low-resolution images covering long distances and large-scale data allowing for rough examination are being provided, so their uses are seriously limited. Therefore, in this paper, we construct spatial information of forest area by using unmanned aerial vehicle and seek efficient utilization and policy improvement in the field of environmental impact assessment. As a result, high-resolution images and data from UAVs can be used to identify the location status of SEIA, EIA, and small scale EIA project plans and to evaluate detailed environmental impact analysis. In addition, when provided together with infographics about Post-environmental impact investigation, it was confirmed that the possibility of periodic spatial information construction and evaluation can be used throughout the entire project contents and project post-process.In order to provide sophisticated infographics for the EIA, drone photography and GCP surveying methods were derived.The results of this study will be used as a basis for improving high-resolution monitoring and environmental impact assessment in the forest sector.

• Structural Engineering and Mechanics
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• v.53 no.3
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• pp.481-495
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• 2015

Many hydropower stations in southwest China are located in regions of brittle rock mass with high geo-stresses. Under these conditions deep fractured zones often occur in the sidewalls of the underground caverns of a power station. The theory and methods of fracture and damage mechanics are therefore adopted to study the phenomena. First a flexibility matrix is developed to describe initial geometric imperfections of a jointed rock mass. This model takes into account the area and orientation of the fractured surfaces of multiple joint sets, as well as spacing and density of joints. Using the assumption of the equivalent strain principle, a damage constitutive model is established based on the brittle fracture criterion. In addition the theory of fracture mechanics is applied to analyze the occurrence of secondary cracks during a cavern excavation. The failure criterion, for rock bridge coalescence and the damage evolution equation, has been derived and a new sub-program integrated into the FLAC-3D software. The model has then been applied to the stability analysis of an underground cavern group of a hydropower station in Sichuan province, China. The results of this method are compared with those obtained by using a conventional elasto-plastic model and splitting depth calculated by the splitting failure criterion proposed in a previous study. The results are also compared with the depth of the relaxation and fracture zone in the surrounding rock measured by field monitoring. The distribution of the splitting zone obtained both by the proposed model and by the field monitoring measurements are consistent to the validity of the theory developed herein.

• Structural Monitoring and Maintenance
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• v.1 no.1
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• pp.131-157
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• 2014

Special track systems used to divert a train to other directions or other tracks are generally called 'railway turnout'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction complexities may dominate the choice of track forms or certain components. With the difficulty to seek for high-quality timbers with dimensional stability, a methodology to replace aged timber bearers in harsh dynamic environments is to adopt an alternative material that could mimic responses and characteristics of timber in both static and dynamic loading conditions. A critical review has suggested an application of an alternative material called fibre-reinforced foamed urethane (FFU). The full-scale capacity design makes use of its comparable engineering characteristics to timber, high-impact attenuation, high damping property, and a longer service life. A field trial to investigate in-situ behaviours of a turnout grillage system using an alternative material, 'fibre-reinforced foamed urethane (FFU)' bearers, has been carried out at a complex turnout junction under heavy mixed traffics at Hornsby, New South Wales, Australia. The turnout junction was renewed using the FFU bearers altogether with new special track components. Influences of the FFU bearers on track geometry (recorded by track inspection vehicle 'AK Car'), track settlement (based on survey data), track dynamics, and acoustic characteristics have been measured. Operational train pass-by measurements have been analysed to evaluate the effectiveness of the replacement methodology. Comparative studies show that the use of FFU bearers generates higher rail and sleeper accelerations but the damping capacity of the FFU help suppress vibration transferring onto other track components. The survey data analysis suggests a small vertical settlement and negligible lateral movement of the turnout system. The static and dynamic behaviours of FFU bearers appear to equate that of natural timber but its service life is superior.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.2
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• pp.31-44
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• 2016

This study analyzed pore water pressure, earth pressure and settlement through field monitoring on the project site in which raising embankments are being built through backside extension, and compared the behaviors of seepage analysis, slope stability analysis and stress-strain during flood water levels and rapid drawdown under steady state and transient condition. The variation of pore water pressure showed an increase during the later period in both upstream and downstream slope, with downstream slope more largely increased than upstream slope overall. The variation of earth pressure increased according to the increase of embankment heights, while the change largely showed in the upstream slope, it was slowly increased in the downstream slope. The settlements largely increased until 23 m as embankment heights increased, and showed very little settlement overall. Under a steady state and transient conditions, the seepage quantity per day and leakage quantity per 100 m of embankment against total storage were shown to be stable for piping. The hydraulic gradient at the core before and after raising embankments was greater than the limit hydraulic gradient, showing instability for piping. The safety factor of upstream and downstream slopes were shown to be very large at a steady state, while the upstream slopes greatly decreased at a transit conditions, downstream slopes did not show any significant changes. The horizontal settlements, the maximum shear strain and stress are especially distributed at the connecting portion of the existing reservoir and the new extension of backside. Accordingly, the backside extension method should be designed and reinforced differently from the cases of other types reservoirs.