• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6D
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• pp.587-598
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• 2012

Successful implementation of infrastructure asset management system can be started with rich and reliable data. However, measurement errors in the data have always existed in the real world caused for many unknown reasons. It disturbs maintenance activities of agencies, and makes negative effects to reliability of research results on forecasting deterioration process and life cycle cost. Above all, it makes a contradiction that road agencies cannot believe their inspection data surveyed by their hands. It is particularly serious in the road pavement management field. Although road agencies are well recognized the fact, inspecting without measurement error would be a great challenge. Considering the facts, this paper aimed to suggest statistical error processing methods to correct latent error included in pavement surface inspection data. As alternatives, this paper suggested two methods based on probability distribution to consider structure of error and reliability of the data. The suggested methods were empirically tested by using pavement inspection data from Korean National Highway. As the result, this paper confirmed that conventional error processing that just removes only visible errors is not enough to cover uncertainty in pavement deterioration process. The suggested methods would be useful for improving reliability of analysis results required for road infrastructure asset management.

• Analytical Science and Technology
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• v.13 no.4
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• pp.403-411
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• 2000

This study described a method of thermoluminescence dating of pottery shards using subtraction method. TL measurement was achieved using two different types of samples prepared by quartz inclusion method and fine-grain technique. Fine grains (size range: $5-10{\mu}m$) were separated by suspending grounded pottery samples into acetone solution and sedimentation quantitatively. In quartz inclusion method quartz grains in the size range of 90 to $125{\mu}m$ diameter were obtained by extracting the quartz crystals embed in the pottery shards and etching them with 1.0 M HF solutions. The archaeological dose of both the quartz and fine grains was determined from the dose calibration curves obtained from sequential irradiation of $^{137}Cs$ gamma and $^{241}Am$ alpha source to the samples and TL measurement of natural samples, in which the alpha dose of 4.60 Gy for the Packjae pottery was obtained using subtraction method. Annual alpha dose rates ($3.05{\pm}0.11$ mGy/yr.) were determined by the analysis of U, Th contents in the pottery shards and evaluation of the values with Bell's equation. Dividing the alpha dose accumulated in the pottery shards by the annual alpha dose rate, we found age of approximately $1508{\pm}80$ years B.P. (AD. ca. 492 yr.) for the Packjae pottery. It matches well with the archeological age estimate (middle of 5th century) within 10 percent uncertainty and thereby conforms the age of the pottery sample.

• Journal of the Korean earth science society
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• v.39 no.6
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• pp.533-544
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• 2018

Rainfall is one of the most important meteorological variables in meteorology, agriculture, hydrology, natural disaster, construction, and architecture. Recently, satellite remote sensing is essential to the accurate detection, estimation, and prediction of rainfall. In this study, the accuracy of Integrated Multi-satellite Retrievals for GPM (IMERG) product, a composite rainfall information based on Global Precipitation Measurement (GPM) satellite was evaluated with ground observation data in the inland of Korea. The Automatic Weather Station (AWS)-based rainfall measurement data were used for validation. The IMERG and AWS rainfall data were collocated and compared during one year from January 1, 2016 to December 31, 2016. The coastal regions and islands were also evaluated irrespective of the well-known uncertainty of satellite-based rainfall data. Consequently, the IMERG data showed a high correlation (0.95) and low error statistics of Bias (15.08 mm/mon) and RMSE (30.32 mm/mon) in comparison to AWS observations. In coastal regions and islands, the IMERG data have a high correlation more than 0.7 as well as inland regions, and the reliability of IMERG data was verified as rainfall data.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.2
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• pp.35-42
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• 2014

The purpose of this study is to analyze job stress factors of hospital workers, which has an effect on their turnover intention. For identifying the influences on turnover intention, types of hospitals (university hospital, general hospital, private hospital) and types of workers(office workers, technical workers, and nursing staffs) were categorized. We went to the hospitals and carried out the survey under the cooperation with the concerned hospitals. The period of survey was from 23. Sep. 2013 to 30. Oct. 2013, and 293 worker participated in the survey. On the basis of the previous study, the measurement of job stress factors and turnover intention was set up as the survey method, and its reliability and validity were measured. The stress factors were subdivided into seven factors; occupational climate, organizational system, autonomy job control, uncertainty of getting a new job, job ability to perform, job demand, job ambiance. The value of job stress factors by the measuring instrument, Cronbach's Alpha, was 0.805 and the value of the subordination variable of turnover intention was 0.881. IBM SPSS Statistics 21 was used as the statistic analysis tool and the descriptive statistics about job stress factors. As a result, the turnover intention were analyzed depending on the types of hospitals, job groups, working years, and gender. Result shows that the job stress factors are differed according to the types of hospitals, and these job stress factors have influence on turnover intention. Therefore, it could be considered that, if the hospital managers find out the major job stress factors of their employees and resolve them in advance, the job stress of the hospital workers and their turnover intention can be reduced.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.61-66
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• 2008

In railroad operation, turnout is the device designed to provide very critical functions of moving the train to the neighboring rail. It's the only movable section among the rail and track equipment, which has a complicated structure and as rapid movement between the wheel and rail during operation is unavoidable, the safety and the vibration caused by the impact load of the passing train becomes always the major concern. Response to rail vibration tends to vary depending on physical properties of the rail, rail base and the ground, making it difficult to estimate the quantitative outcome through the measurement. Thus, experimental or empirical approach, rather than an analytic method, has been more commonly employed to deal with the ground vibration. To predict the vibration of the turnout, an experimental value and the measured values are applied in parallel to the factors with a high degree of uncertainty. This study hence was intended to compare and analyze the vibration values measured at the crossing part of manganese turnout by type of train and turnout and distance, as well as predict the intensity of vibration generated at the crossing part of manganese turnout when tilting train accelerates.

• Journal of the Korean Magnetics Society
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• v.12 no.6
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• pp.206-211
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• 2002

We have constructed a new kind of magnetic motion capture sensor based on the pulse magnetic field method. 3-orthogonal magnetic pulse fields were generated in turns only one period of sinusoidal waveform using 3-orthogonal magnetic dipole coils, ring counter and analog multiplier. These pulse magnetic fields were measured with 3-orthogonal search coils, of which induced voltages by the x-, y-, and l-dipole sources using S/H amplifier at the time position of maximum induced voltage. Using the developed motion capture sensor, we can measure position of sensor with uncertainty of ${\pm}$0.5％ in the measuring range from ${\pm}$0.5 m to ${\pm}$1.5 m.

• Journal of the Korean Geotechnical Society
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• v.28 no.1
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• pp.41-53
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• 2012

As the permeability of soil adjacent to the vertical drain has a decisive effect on the rate of consolidation, the permeability of smear zone governs the rate of radial consolidation of PVD installed soft ground. In this study, a method was suggested to analyze the radial consolidation, based on consolidation characteristics of remolded clay, and was used to evaluate the consolidation of soft clay layer in Busan Newport. The suggested method provides more reliable consolidation behaviors than the conventional approach, which is based on the consolidation characteristics of undisturbed clay. The suggested method is also observed to be relatively insensitive to the uncertainty of $k_h/k_s$. The comparison between the analysis and field measurement revealed that the suggested method provided a reliable prediction on the rate of consolidation of PVD installed Busan new port clay and that an appropriate extent of smear zone was evaluated as about $3d_w$ by back analysis.

• The Journal of Engineering Geology
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• v.30 no.2
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• pp.131-145
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• 2020

The construction on these flimsy ground, activation of unsymmetrical surcharges, can often cause of the embankment road lateral flow or the destruction of the activities. In this study, the stability of the abutment pile foundation installed on soft ground and its behavior has been evaluated. The behavior of the abutment pile foundation under lateral flow was studied by verifying the behavior and reinforcement effects of the abutment pile foundation of previous studies about horizontal loads acting on the pile due to the lateral flow of the ground by performing finite element analysis. As a result of the consolidation analyses, the undrained cohesion or the strength of the soft ground, was increased by about 1.1 to 1.8 times by the increase in the strength of the soft ground according to the degree of consolidation. It is deemed reasonable to use 3.8 cm of the allowable displacement both economically and constructively, but considering the importance of the structure and the uncertainty of the ground, measurement shall be carried out during construction and thorough safety management of the lateral flow should be done.

• Korean Journal of Remote Sensing
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• v.26 no.1
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• pp.29-38
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• 2010

It is necessary to develop an integration model which can account for various data acquired at different measurement scales in environmental thematic mapping with high-resolution ground survey data and relatively low-resolution remote sensing data. This paper presents and applies a multi-scale geostatistical methodology for downscaling of thematic maps generated from lowresolution remote sensing data. This methodology extends a traditional ordinary kriging system to a block kriging system which can account for both ground data and remote sensing data which can be regarded as point and block data, respectively. In addition, stochastic simulation based on block kriging is also applied to describe spatial uncertainty attached to the downscaling. Two downscaling experiments including SRTM DEM and MODIS Leaf Area Index (LAI) products were carried out to illustrate the applicability of the geostatistical methodology. Through the experiments, multi-scale geostatistics based on block kriging successfully generated relatively high-resolution thematic maps with reliable accuracy. Especially, it is expected that multiple realizations generated from simulation would be effectively used as input data for investigating the effects of uncertain input data on GIS model outputs.

• Nuclear Engineering and Technology
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• v.19 no.2
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• pp.107-114
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• 1987

Using a solution of $^{137}$ Cs as a tracer, radioactivity of a $^{137}$ Cs solution is measured by coincidence and anticoincidence counting methods. Sample sources in this study are fabricated by mixing $^{137}$ Cs with tracer, and the mixing ratios are 1/3 and 1/5, respectively in coincidence and anticoincidence methods. Specific activities of a $^{137}$ Cs solution are calculated by means of f-channel low energy threshold level variation and efficiency extrapolation. The results obtained by coincidence and anticoincidence counting methods are 552.78 kBq/g and 554.32kBq/g, respectively on the reference date and the combined uncertainties are 1.60kBq/g and 1.51kBq/g for each method. These two results show a good agreement within the uncertainty range.