• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.325-333
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• 2010

In this study, new moment-resisting precast concrete beam-column joint made up of hybrid steel concrete was developed and tested. This beam-column joint is proposed for use in moderate seismic regions. It has square hollow tubular section in concrete column and connecting plate in precast U-beam. The steel elements in column and beam members were connected using bolt. Furthermore, in order to prevent the premature failure of concrete in hybrid steel-concrete connection, ECC(engineered cementitious composite) was used. An experimental study was carried out investigating the joint behavior subjected to reversed cyclic loading and constant axial compressive load. Two precast beam-column joint specimens and monolithic reinforced concrete joint specimen were tested. The variables for interior joints were cast-in-situ concrete area and transverse reinforcement within the joint. Tests were carried out under displacement controlled reverse cyclic load with a constant axial load. Joint performance is evaluated on the basis of connection strength, stiffness, energy dissipation, and displacement capacity. The test results showed that significant differences in structural behavior between the two types of connection because of different bonding characteristics between steel and concrete; steel and ECC. The proposed joint detail can induce to move the plastic hinge out of the ECC and steel plate. And proposed precast connection showed better performance than the monolithic connection by providing sufficient moment-resisting behavior suitable for applications in moderate seismic regions.

• Journal of Korean Society of Transportation
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• v.23 no.4 s.82
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• pp.71-79
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• 2005

Existing arterial link travel time estimation methods relying on either aggregate point-based or individual section-based traffic data have their inherent limitations. This paper demonstrates the utility of data fusion for improving arterial link travel time estimation. If the data describe traffic conditions, an operator wants to know whether the situations are going better or worse. In addition, some traffic information providing strategies require predictions of what would be the values of traffic variables during the next time period. In such situations, it is necessary to use a prediction algorithm in order to extract the average trends in traffic data or make short-term predictions of the control variables. In this research. a multi-step ahead prediction algorithm using Data fusion was developed to predict a link travel time. The algorithm performance were tested in terms of performance measures such as MAE (Mean Absolute Error), MARE(mean absolute relative error), RMSE (Root Mean Square Error), EC(equality coefficient). The performance of the proposed algorithm was superior to the current one-step ahead prediction algorithm.

• Journal of the Korean Wood Science and Technology
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• v.34 no.3
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• pp.1-7
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• 2006

Anatomical and physical properties of kenaf grown in Chuncheon, Korea were investigated using light and scanning electron microscopy and X-ray diffraction method. Bast fiber, phloem ray, cortex parenchyma cell and sieve tube member were observed in phloem, and vessel element, fiber and ray in xylem. Solitary and multiple radial pores in xylem existed. The cell types of ray parenchyma in radial section were procumbent, upright and square cells. The length of bast fiber increased with increasing the growth period. The length of wood fiber was 0.74~0.82 mm, but was not significantly different between the growth period and stem height. Relative crystallinity was 53~74% in phloem and 43~58% in xylem. Cellulose crystallinity width was 2.68~3.24 nm in phloem and 2.46~2.95 nm in xylem. The green moisture content and green density increased but basic density decreased with increasing the stem height.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.2
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• pp.49-56
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• 2001

The possibility of a noise reduction of piezoelectric single Panels is experimentally studied. Piezoelectric single panel is basically a plate structure on which piezoelectric patch with shunt circuit is mounted. The use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. Piezo-damping is implemented by using a newly proposed tuning method. This method is based on electrical impedance model and maximizing the dissipated energy at the shunt circuit. By measuring the electrical impedance at the piezoelectric patch bonded on a structure, an equivalent electrical model is constructed near the system resonance frequency. Resonant shunt circuit for piezoelectric shunt damping is composed of register and inductor in series, and they are determined by maximizing the dissipated energy throughout the circuit. The transmitted noise reduction performance of single Panel is tested on an acoustic tunnel. The tunnel is a tube with a square cross section and a loud speaker is mounted at one side of the tube as a sound source. Panels are mounted in the middle of the tunnel and the transmitted sound pressure across Panels is measured. By enabling the piezoelectric shunt damping noise reduction is achieved at the resonance frequencies as well. Piezoelectric single panel with piezoelectric shunt damping is a promising technology for noise reduction in a broadband frequency.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.316-322
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• 2009

This paper presents a preliminary study to monitor the lateral behavior of pile foundation using multiplexed fiber Bragg grating(FBG) sensors. In the Preliminary study, an 1.7 meter long cantilever beam with the shape of square hollow box was fabricated and tested under the static loading. Four FBG sensors were multiplexed in a single optical fiber and installed into the top and bottom of the cantilever beam. The strains are directly measured from FBG sensors followed by curvature calculations based on the plane section assumption. Vertical deflections are then estimated using the regression analyses based on the geometric relationships. It has been found that excellent correlation with conventional sensing system was observed. The success of the test encourages the use of the FBG sensing system as a monitoring system for pile foundations. However, further consideration should be given in the case of the sensor malfunction for the practical purpose.

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.31-41
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• 2017

Foreign tourists who are visiting Korea urban tourism destination have been continuedly growing and more various tourism products and service are requested to fit those foreign tourists' needs and wants. Accordingly, tourism contents and its satisfaction in urban tourism destination have been developing to provide more valuable products and service to tourists. This study was conducted to segment foreign tourists based on 4 different tourism urban destination contents, including destination facility contents, leisure entertainment contents, shopping contents, accommodation contents. Cluster analysis provided four different groups based on the mean score of urban tourism destination contents. MANOVA was conducted to identify whether ot not there are differences among the segmented groups in terms of travel performances and destination loyalty, Chi-square analysis were also conducted to see if there are differences among the segmented groups based on demographic informations. Theoretical and practical implication were discussed in the conclusion section. The results of this study would be helpful for tourism products planners and developers.

• Journal of the Korean Society of Safety
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• v.35 no.2
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• pp.28-33
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• 2020

Recently, the overseas construction market has been actively promoted for about 10 years, and overseas dam construction has been continuously performed. For the economic and safe construction of the dam, it is important to prepare the main dam construction plan considering the design frequency of the diversion tunnel and the cofferdam. In this respect, the prediction of river level during the rainy season is significant. Since most of the overseas dam construction sites are located in areas with poor infrastructure, the most efficient and economic method to predict the water level in dam construction is to use the upstream water level. In this study, a linear regression model, which is one of the simplest statistical methods, was proposed and examined to predict the downstream level from the upstream level. The Pyeongchang River basin, which has the characteristics of the upper stream (mountain stream), was selected as the target site and the observed water level in Pyeongchang and Panwoon gaging station were used. A regression equation was developed using the water level data set from August 22th to 27th, 2017, and its applicability was tested using the water level data set from August 28th to September 1st, 2018. The dependent variable was selected as the "level difference between two stations," and the independent variable was selected as "the level of water level in Pyeongchang station two hours ago" and the "water level change rate in Pyeongchang station (m/hr)". In addition, the accuracy of the developed equation was checked by using the regression statistics of Root Mean Square Error (RMSE), Adjusted Coefficient of Determination (ACD), and Nach Sutcliffe efficiency Coefficient (NSEC). As a result, the statistical value of the linear regression model was very high, so the downstream water level prediction using the upstream water level was examined in a highly reliable way. In addition, the results of the application of the water level change rate (m/hr) to the regression equation show that although the increase of the statistical value is not large, it is effective to reduce the water level error in the rapid level rise section. Accordingly, this is a significant advantage in estimating the evacuation water level during main dam construction to secure safety in construction site.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.10
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• pp.1384-1389
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• 2006

Prolactin plays an important role in mammary gland development, milk section initiation and maintenance of lactation, so the bovine prolactin gene is considered as a potential quantitative trait locus affecting milk performance traits in dairy cattle. In this study, to determine the association between prolactin and milk performance traits, the genetic polymorphisms of a part of the prolactin gene were detected in a population of 649 cows of Chinese Holstein Dairy Cattle. Three SNPs in the promoter and one SNP in the intron1 of prolactin were identified, which was A/C (-767), G/T (-485), C/A (-247), and C/T (427), respectively. Statistical results indicated that one of SNP within promote, CHBP2, was significantly associated with milk yield (p<0.01), fat yield (p<0.05), protein yield (p<0.01), and protein percentage (p<0.05). The cows with genotype BB of CHBP2 had significantly higher milk yield (p<0.01), fat yield (p<0.05), and protein yield (p<0.01) than those of cows with genotype AA, while cows with genotype AA showed the highest protein percentage (p<0.05). In addition, based on the nine major haplotypes constructed from the four SNPs, the association analysis between diplotypes and milk performance trait was carried out. Results showed that the least square mean for fat yield of diplotype H2H8 was significantly higher than those of other eleven diplotypes (p<0.05). Our findings implied that CHBP2 and H2H8 of prolactin would be useful genetic markers in selection program on milk performance traits in Holstein Dairy Cattle.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.679-685
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• 2017

Computed tomography has widely been used to diagnose patient disease, and patient dose also increase rapidly. To reduce the patient dose by CT, various techniques have been applied. The iterative reconstruction is used in view of image reconstruction. Image quality of the reconstructed section image through algebraic reconstruction technique, one of iterative reconstruction methods, was examined by the normalized root mean square error. The computer program was written with the Visual C++ under the parallel beam geometry, Shepp-Logan head phantom of $512{\times}512$ size, projections of 360, and detector-pixels of 1,024. The forward and backward projection was realized by Joseph method. The minimum NRMS of 0.108 was obtained after 10 iterations in the regularization parameter of 0.09-0.12, and the optimum image was obtained after 8 and 6 iterations for 0.1% and 0.2% noise. Variation of optimum value of the regularization parameter was observed according to the phantom used. If the ART was used in the reconstruction, the optimal value of the regularization parameter should be found in the case-by-case. By finding the optimal regularization parameter in the algebraic reconstruction technique, the reconstruction time can be reduced.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.979-986
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• 2010

This paper presents an algorithm for retrieving precise radar cross sections(RCS) of various trihedral corner reflectors (TCR) which are external calibrators of synthetic aperture radar(SAR) systems. The theoretical RCSs of the TCRs are computed based on the physical optics(PO), geometrical optics(GO), and physical theory of diffraction(PTD) techniques; that is, the RCS computation includes the single reflections(PO), double reflections(GO-PO), triple reflections(GO-GO-PO), and edge diffractions(PTD) from the TCR. At first, we acquire an SAR image of the area that five TCRs installed in, and then extract the RCS of the TCRs. The RCSs of the TCRs are extracted accurately from the SAR image by adding up the power spill, which is generated due to the radar IRF(Impulse Response Function), using a square window. We compare the extracted RCSs with the theoretical RCSs and analyze the difference between the theoretical and experimental RCSs of the TCR for various window sizes and various backscattering coefficient levels of the adjacent area. Finally, we propose the minimum size of the integration area and the maximum level of the backscattering coefficients for the adjacent area.