• Structural Engineering and Mechanics
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• v.85 no.5
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• pp.693-707
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• 2023

In order to deeply reveal the working mechanism of ultra-high performance concrete (UHPC) filled steel tubular columns (UHPCFSTs) under cyclic loading, a three-dimension (3D) macro-mesoscale finite element (FE) model was established considering the randomness of steel fibers and the damage of UHPC. Model correctness and reliability were verified based on the experimental results. Next, the whole failure process of UHPC reinforced with steel fibers, passive confinement effect and internal force distribution laws were comprehensively analyzed and discussed. Finally, a simplified and practical method was proposed for predicting the ultimate bending strengths of UHPCFSTs. It was found that the non-uniform confinement effect of steel tube occurred when the drift ratio exceeded 0.5%, while the confining stress increased then decreased afterwards. There was preferable synergy between the steel tube and UHPC until failure. Compared with experimental results, the ultimate bending strengths of UHPCFSTs were undervalued by the current code provisions such as AISC360-10, EC4 and GB50936 with computed mean values (MVs) of 0.855, 0.880 and 0.836, respectively. The proposed practical method was highly accurate, as evidenced by a mean value of 1.058.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.72-81
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• 2023

We introduce tightly-coupled GNSS-LiDAR-Inertial state estimator, which is capable of SLAM (Simultaneously Localization and Mapping) and autonomous driving. Long term drift is one of the main sources of estimation error, and some LiDAR SLAM framework utilize loop closure to overcome this error. However, when loop closing event happens, one's current state could change abruptly and pose some safety issues on drivers. Directly utilizing GNSS (Global Navigation Satellite System) positioning information could help alleviating this problem, but accurate information is not always available and inaccurate vertical positioning issues still exist. We thus propose our method which tightly couples raw GNSS measurements into LiDAR-Inertial SLAM framework which can handle satellite positioning information regardless of its uncertainty. Also, with NLOS (Non-light-of-sight) satellite signal handling, we can estimate our states more smoothly and accurately. With several autonomous driving tests on AGV (Autonomous Ground Vehicle), we verified that our method can be applied to real-world problem.

• Steel and Composite Structures
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• v.47 no.3
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• pp.339-353
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• 2023

The primary objective of the current study is to optimize and evaluate the seismic performance of steel momentresisting frame (MRF) structures considering soil-structure interaction (SSI) effects. The structural optimization is implemented in the context of performance-based design in accordance with FEMA-350 at different confidence levels from 50% to 90% by taking into account fixed- and flexible-base conditions using an efficient metaheuristic algorithm. Nonlinear response-history analysis (NRHA) is conducted to evaluate the seismic response of structures, and the beam-on-nonlinear Winkler foundation (BNWF) model is used to simulate the soil-foundation interaction under the MRFs. The seismic performance of optimally designed fixed- and flexible-base steel MRFs are compared in terms of overall damage index, seismic collapse safety, and interstory drift ratios at different performance levels. Two illustrative examples of 6- and 12-story steel MRFs are presented. The results show that the consideration of SSI in the optimization process of 6- and 12-story steel MRFs results in an increase of 1.0 to 9.0 % and 0.5 to 5.0 % in structural weight and a slight decrease in structural seismic safety at different confidence levels.

• Earthquakes and Structures
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• v.25 no.5
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• pp.343-358
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• 2023

The superelastic viscous damper (SVD) is a hybrid passive control device comprising a viscoelastic damper and shape memory alloy (SMA) cables connected in series. The SVD is an innovative damper through which a large amount of seismic energy can dissipate. The current study assessed the seismic collapse induced by steel moment-resisting frames (SMRFs) equipped with SVDs and compared them with the performance of special MRFs and buckling restrained brace frames (BRBFs). For this purpose, nonlinear dynamic and incremental dynamic analysis (IDA) were conducted in OpenSees software. Both 5- and 9-story special MRFs, BRBFs, and MRFs equipped with the SVDs were examined. The results indicated that the annual exceedance rate for maximum residual drifts of 0.2% and 0.5% for the BRBFs and MRFs with SVDs, respectively, were considerably less than for SMRFs with reduced-beam section (RBS) connections and that the seismic performances of these structures were enhanced with the use of the BRB and SVD. The probability of collapse due to residual drift in the SVD, BRB, and RBS frames in the 9-story structure was 1.45, 1.75, and 1.05 times greater than for the 5-story frame.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.1
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• pp.41-46
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• 2024

The current study investigates the seismic performance of shear-dominant RC columns retrofitted with iron-based shape memory alloy (Fe SMA). Three RC columns with insufficient transverse reinforcement were designed and fabricated for lateral cyclic loading tests. Before testing, two specimens were externally confined with carbon fiber-reinforced polymer (CFRP) sheets and self-prestressed Fe SMA strips. The test results showed that both CFRP and Fe SMA performed well in preventing severe shear failure exhibited by the unretrofitted control specimen. Furthermore, the two retrofitted specimens showed ductile flexural responses up to the drift ratios of ±8%. In terms of damage control, however, the Fe SMA confinement was superior to CFRP confinement in that the spalling of concrete was much less and that the rupture of confinement did not occur.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8327-8333
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• 2016

Background: The recent epidemiologic transition in Thailand, with decreasing incidence of infectious diseases along with increasing rates of chronic conditions, including cancer, is a serious problem for the country. Breast cancer has the highest incidence rates among females throughout Thailand. Lampang is a province in the upper part of Northern Thailand. A study was needed to identify the current burden, and the future trends of breast cancer in upper Northern Thai women. Materials and Methods: Here we used cancer incidence data from the Lampang Cancer Registry to characterize and analyze the local incidence of breast cancer. Joinpoint analysis, age period cohort model and Nordpred package were used to investigate the incidences of breast cancer in the province from 1993 to 2012 and to project future trends from 2013 to 2030. Results: Age-standardized incidence rates (world) of breast cancer in the upper parts of Northern Thailand increased from 16.7 to 26.3 cases per 100,000 female population which is equivalent to an annual percentage change of 2.0-2.8%, according to the method used. Linear drift effects played a role in shaping the increase of incidence. The three projection method suggested that incidence rates would continue to increase in the future with incidence for women aged 50 and above, increasing at a higher rate than for women below the age of 50. Conclusions: The current early detection measures increase detection rates of early disease. Preparation of a budget for treatment facilities and human resources, both in surgical and medical oncology, is essential.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.2
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• pp.160-167
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• 2009

To detect islanding mode when the grid is being tripped is a major safety issue in the Utility Interactive Photo Voltaic (UIPV) system. In this paper, analytical design method is suggested for AFD & RPV method under IEEE 929-2000 recommended islanding test condition. We have discussed that there is a same point. we injected reactive component of the current by AFD & RPV methods, but the current reference generated is other waveform. Possible if amount of reactive components in this methods are same each method, there is happened same rates frequency variation. To verify the validity of the analytical comparison, this paper presents simulation and experimental results from single phase, 3[kW] inverter for the transformerless UIPV system.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6735-6740
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• 2015

Background: With the recent epidemiologic transition in Thailand, featuring decreasing incidences of infectious diseases along with increasing rates of chronic conditions, cancer is becoming a serious problem for the country. Breast cancer has the highest incidence rates among females, not only in the southern regions, but throughout Thailand. Surat Thani is a province in the upper part of Southern Thailand. A study was needed to identify the current burden, and the future trends of breast cancer. Materials and Methods: Here we used cancer incidence data from the Surat Thani Cancer Registry to characterize the incidences of breast cancer. Joinpoint analysis was used to investigate the incidences in the province from 2004 to 2012 and to project future trends from 2013 to 2030. Results: Age-standardized incidence rates (world) of breast cancer in the upper parts of Southern Thailand increased from 35.1 to 59.2 cases per 100,000 female population, which is equivalent to an annual percentage change of 4.5-4.8%. Linear drift effects played a role in shaping the increase of incidence. Joinpoint projection suggested that incidence rates would continue to increase in the future with incidence for women aged 50 and above, at a higher rate than for women below the age of 50. Conclusions: The current early detection measures increase detection rates of early disease. Preparation of a budget for treatment facilities and human resources, both in surgical and medical oncology, is essential.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.485-492
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• 2019

The observation system has been developed to investigate the rip currents at Haeundae beach using X-band marine radar. X-band radar system can observe shape, size, and velocity of rip currents, which is difficult to obtain through field observation by conventional device. Algorithms which automatically detect locations, shapes, and magnitudes of rip currents were developed using time averaged X-band radar sea clutter images. X-band sea clutter images are transformed through 3D FFT into 2D wave number spectrum and frequency spectrum. Rip current velocities were estimated using differences in wave-number spectra and wave frequency spectra due to Doppler shift. The algorithm was verified by drift experiments. At Haeundae beach, the radar system exactly located the rip currents and found to be sustained for 1-2 days at fixed locations.

• Korean Journal of Digital Imaging in Medicine
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• v.8 no.1
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• pp.51-55
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• 2006

The effects of Asaddition in amorphous selenium(a-Se) films for digital X-ray conversion material have been studied using the moving photocarrier grating(MPG) technique. This method utilizes the moving interference pattern generated by the superposition of the two frequency shifted laser beams for the illumination of the sample. This moving intensity grating induces a short circuit current, j$_{sc}$ in a-Se:As film. The transport parameters of the sample are extracted from the grating-velocity dependent short circuit current induced in the sample along the modulation direction. The electron and hole mobility, and recombination lifetime of a-Se films with arsenic(As) additions have been obtained. We have found an Increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density. The transport properties for As doped a-Se films obtained by using MPG technique have been compared with X-ray sensitivity for a-Se:As device. The fabricated a-Se(0.3% As) device film exhibited the highest X-ray sensitivity out of 5 samples.