• Journal of the Korean Geophysical Society
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• 제3권2호
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• pp.127-138
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• 2000

This study was conducted to examine the differences between dynamic and static elastic constants by use of some laboratory tests of cement mortar specimens which have different water/cement mixing ratios. Specific gravity measurement, ultrasonic velocity estimating and uniaxial compression test were adopted to acquire the dynamic and static elastic constants. Digital data acquisition and processing enhanced the accuracy of estimating the velocities of specimens drastically, Also, the method using the gradient of propagation delay time in according to increment of specimen length more enhanced the accuracy than the method using the only one specimen length over total propagation time. The correlation between density and the P and S wave velocity of specimens shows reliable positive relation and the correlation between density and the strength of uniaxial compression has the similar relationship. The dynamic Young's modulus $(E_D)$ is alway greater than the static Young's modulus $(E_S)$ and there is increasing tendency of the ratio $(E_D/E_S)$ according to the increase of density or strength of the specimens. On the other hand, there is no typical relationship between dynamic Poisson's ratio $({\nu}_D)$ and static Poisson's ratio $({\nu}_S)$ and just the ratio of ${\nu}_D/{\nu}_S$ ranges front 69 to 122 %.

• Journal of the Korean Association of Geographic Information Studies
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• 제7권4호
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• pp.77-87
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• 2004

It is important for hydrographers to extract the accurate cross section of a river for the hydrographical analysis of the topography. Aerial photographs were used to extract the cross section of a river for the advantages of the accuracy and economical efficiency in this study, while the direct measurement has been used in existing studies. An ortho-rectified photo map using imageries taken by the PKNU 2 (High-resolution, multi-spectral, aerial photographic system developed by our laboratory) was generated using the surveyed data and a digital map. The cross section of a river that was obtained from the ortho-rectified by the surveyed Kinematic data of GPS was compared with the result using ImageStation stereo-plotter of corp. Z/I Imaging. As a result of this study, the RMSE in the ortho-rect process using the surveyed GPS data was lowered as from 5.5788 pixels (about 2m) to 2.84 (about 1m) in comparison with it in the process using a digital map. The surveyed kinematic GPS in extraction of the cross section of a river was excellent as 6.6cm of the planimetric and precision in the confidence level of 95%. The correlation coefficient between the result from the using stereo-plotter and the extraction of cross section of a river using aerial photos was 0.8 hydrographical acquisition of it using PKNU 2 imagery will be possible.

• Journal of IKEEE
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• 제18권2호
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• pp.272-281
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• 2014

In electrical impedance tomography (EIT), modified Newton Raphson (mNR) method is widely used inverse algorithm for static image reconstruction due to its convergence speed and estimation accuracy. The unknown conductivity distribution is estimated iteratively by minimizing a cost functional such that the residual error namely the difference in measured and calculated voltages is reduced. Although, mNR method has good estimation performance, EIT inverse problem still suffers from ill-conditioned and ill-posedness nature. To mitigate the ill-posedness, generally, regularization methods are adopted. The inverse solution is highly dependent on the choice of regularization parameter. In most cases, the regularization parameter has a constant value and is chosen based on experience or trail and error approach. In situations, when the internal distribution changes or with high measurement noise, the solution does not get converged with the use of constant regularization parameter. Therefore, in this paper, in order to improve the image reconstruction performance, we propose a new scheme to determine the regularization parameter. The regularization parameter is computed based on residual error and updated every iteration. The proposed scheme is tested with numerical simulations and laboratory phantom experiments. The results show an improved reconstruction performance when using the proposed regularization scheme as compared to constant regularization scheme.

• Smart Structures and Systems
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• 제20권5호
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• pp.549-562
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• 2017

The US railroad network carries 40% of the nation's total freight. Railroad bridges are the most critical part of the network infrastructure and, therefore, must be properly maintained for the operational safety. Railroad managers inspect bridges by measuring displacements under train crossing events to assess their structural condition and prioritize bridge management and safety decisions accordingly. The displacement of a railroad bridge under train crossings is one parameter of interest to railroad bridge owners, as it quantifies a bridge's ability to perform safely and addresses its serviceability. Railroad bridges with poor track conditions will have amplified displacements under heavy loads due to impacts between the wheels and rail joints. Under these circumstances, vehicle-track-bridge interactions could cause excessive bridge displacements, and hence, unsafe train crossings. If displacements during train crossings could be measured objectively, owners could repair or replace less safe bridges first. However, data on bridge displacements is difficult to collect in the field as a fixed point of reference is required for measurement. Accelerations can be used to estimate dynamic displacements, but to date, the pseudo-static displacements cannot be measured using reference-free sensors. This study proposes a method to estimate total transverse displacements of a railroad bridge under live train loads using acceleration and tilt data at the top of the exterior pile bent of a standard timber trestle, where train derailment due to excessive lateral movement is the main concern. Researchers used real bridge transverse displacement data under train traffic from varying bridge serviceability levels. This study explores the design of a new bridge deck-pier experimental model that simulates the vibrations of railroad bridges under traffic using a shake table for the input of train crossing data collected from the field into a laboratory model of a standard timber railroad pile bent. Reference-free sensors measured both the inclination angle and accelerations of the pile cap. Various readings are used to estimate the total displacements of the bridge using data filtering. The estimated displacements are then compared to the true responses of the model measured with displacement sensors. An average peak error of 10% and a root mean square error average of 5% resulted, concluding that this method can cost-effectively measure the total displacement of railroad bridges without a fixed reference.

• Journal of Digital Convergence
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• 제13권1호
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• pp.383-396
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• 2015

This study aims to identify factors related to rescreening the private health screening center. Data from private health screening center with seven district centers were analyzed. The number of subjects was 70,250 from 2008 through 2015. Socio-demographic characteristics, morbidity, history, physical measurement, laboratory test, and health behavior factors were analyzed the association with health rescreening using chi-square test and negative binominal regression. 19.2% of subjects were recheck their health status on each year from 2008 to 2012. The socio-demographic characteristics related to reuse private health screening center were male, 30-40 aged, Daegu, Gwangju, Jeonnam and Gyeongnam region residents. And overweight and pre-hypertension were also factors association with number of using the private health screening program. People who control their health risk factors such as alcohol intake, smoking and mental health and execute physical exercise tend to use health screening program regularly. Our finding suggest that customer relationship management can execute and private health screening center enable their strategic plan based on data-evidence.

• Journal of Convergence for Information Technology
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• 제10권3호
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• pp.195-199
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• 2020

This study examined the effect of the nervous-system-stimulating caffeine on the nerve conduction velocity. The purpose of this study is to investigate the effect of caffeine that stimulates the nervous system on nerve conduction test. Although both measurement intervals did not show statistically significant differences when comparing the pre- and post-NCV values within the control and individual experimental groups, it was found that the nerve conductivity in the Axilla-Above Elbow section increased significantly after caffeine intake for the experimental group. Caffeine intake, which has increased the nerve conduction velocity (NCV), was determined to play roles in improving motor skills, muscle strength and nerve performance by temporarily increasing the nerve conduction velocity. Through this study, we learned that caffeine has an influence on the peripheral nervous system as it helps to improve the nerve conduction velocity. upon an appropriate amount of caffeine intake. We hope that these results will help develop treatment and diagnostic methods for patients with nerve dysfunction and myofunctional disorders.

• Korean Journal of Food Science and Technology
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• 제21권5호
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• pp.649-654
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• 1989

The color distribution of fish sauces was studied by using the change in log absorbance per 100nm as a parameter of color tone. A linear relationship was found between the logarithm of absorbance (log A) and wavelength at 450 nm to 650 nm in the color of fish sauces. Change in log A per 100nm $({\Delta}A)$ in the color of the fish sauce products was in the range of 0.55 to 0.59. Absorbance at 450 nm (A 450) of the fish sauce treated with soy sauce koji was high in comparison with A 450 of the fish sauce treated by pronase and control. The color of fish sauces treated with soy sauce koji was dark reddish orange, and was similar to the color of soy sauce. A 450 of every fish sauce increased with the progress of fermentation but ${\Delta}A$of the fish sauces slightly increased at the beginning of fermentation and then decreased at the end of fermentation. In the results of sensory evaluation for the flavor of fish sauce products, the fish sauce product treated with soy sauce koji that 20% salt was added at the first stage was the molt desirable in the strength of flavor, tastefulness and after taste, and the fish sauce was also the best in acceptability.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제15권1호
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• pp.1-10
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• 2003

In this paper, the laboratory test results with middle-sired ,soil box test in modeling the in-situ installing of horizontal drains are discussed the estimation of the optimum negative pressure. The test was carried out in the different vacuum pressure conditions together with the measurement for the settlement and volume change of drained water by the installed drains during the consolidation process. After the test, the water content was measured to both directions of lateral distance from the drain and depth of the soil, to find out the distribution of ground improvement and strength enhancement. From the analysis on the distribution of water content, the gradual application of vacuum pressure to higher level by pre-determined stages starting from low vacuum pressure is found to be effective and desirable. In the comparison of the degrees of consolidation with elapsed time, the calculated value by the prediction method based on the Barren's conventional theory showed a good agreement with the measured value. With this, It is positively considered that the applicability of the prediction method based on Barren's theory to the practical design of horizontal drains can be justified such as in the calculation of drain spacing and consolidation period.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제16권6호
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• pp.3882-3888
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• 2015

The present study was conducted to assess the relationship between obesity and abdominal obesity and Parathyroid hormone (PTH) in adults aged 50 or older (n=3,305) using 2011 Korean National Health and Nutrition Examination Survey (KNHANES) data, which represents national data in Korea. Key study results were as follows: First, the PTH levels increased significantly with an increase in Body mass index (BMI) (p=0.003), shown by sIAD levels after adjusted the variables that affect sIAD levels (age, gender, SBP, DBP, and 25(OH)D). These were $66.25{\pm}0.89ng/dL$ for Normal weight (BMI, < $23.0kg/m^2$), $67.83{\pm}1.07 ng/dL$ for Overweight (BMI, $23.0-24.9kg/m^2$), $70.71{\pm}0.94ng/dL$ for Obesity (BMI,${\geq}25.0kg/m^2$). Second, the PTH level of abdominal obesity group ($69.30{\pm}0.80ng/dL$) was significantly higher (p=0.017) than non-abdominal obesity group ($66.63{\pm}0.74ng/dL$). In conclusion, BMI and waist measurement are positively associated with the PTH levels in Korean adults.

• Korean Journal of Ecology and Environment
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• 제42권1호
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• pp.124-133
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• 2009

Effects of substrates on the relative immigration activities (RIAs) of epilithic diatoms were examined in Sum River, a tributary of South Han River, Korea. Two hundreds of tile substrates coated with 5% agar were deposited at seven study stations (30 tiles per site) for one month from March 7 to April 7, 2008. Water sampling, physico-chemical factor measurement, and diatom analysis were performed in the field and laboratory. Over the study, major epilithic diatom species were Nitzschia amphibia, Navicula subminuscula, Cymbella minuta in both the natural and artificial substrates. Two dominant species, Nitzschia amphibia and Cymbella minuta often found at seven stations. Among all observed taxa, Nav. subminuscula and Caloneis silicula showed the highest RIA, with the value over 15 throughout the study. Regarding the algal morphology, the biraphe type species showed higher RIA than any other morph, while they comprised over 55% of total biomass, indicating a density effect. Additionally, a significant relationship between RIA and 20-day deposited substrate (p<0.05) showed in two diatom species, Nitzschia fonticola, Gomphonema quadripunctatum, which showed relatively high RIAs. These results indicate that the relative immigration activities of epilithic diatom species can be influenced by algal density in the water and substrate, nutrients, and deposited time at least 20 days.