• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.207-215
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• 2003

Developed is a new environment-friendly concrete-block retaining wall system. The conventional analysis methods are not directly applicable because the proposed concrete-block wall system is made of by interlocking the blocks with shear keys. Therefore, the shear analysis as well as stability analysis have been conducted to secure the safety of block-wall system. Overall slope stability analysis was also performed. An appropriate strengthening method was developed to ensure the safety when the block-wall system is relatively high. The method of analysis for strengthening the concrete-block wall system was also proposed. The proposed environment-friendly concrete block retaining wall system shows reasonable safety and can be a good construction method for retaining walls and river bank walls.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.428-433
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• 2010

The notion "block rotation" denotes the operation of exchanging two consecutive sequences of elements uv to vu. There are three already well-known block rotation algorithms called BlockRotation, Juggling and Reversal algorithm. Recently we presented a novel block rotation algorithm called QuickRotation. In this paper we compare QuickRotation to these three known block rotation algorithms. This comparison covers a complexity analysis as well as benchmarking and shows that a switch to QuickRotation is almost always advantageous.

• Ocean Systems Engineering
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• v.8 no.1
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• pp.57-77
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• 2018

The present paper deals with the finite element analysis of water tanks with rigid baffle. Fluid is discretized by two dimensional eight-node isoparametric elements and the governing equation is simulated by pressure based formulation to reduce the degrees of freedom in the domain. Both free vibration and force vibration analysis are carried out for different sizes and positions of block at tank bottom. The fundamental frequency depends on block height and it reduces with the increase of block height. The variation of hydrodynamic pressure on tank walls not only depends of the exciting frequency but also on the size and position of rigid block at tank bottom. The hydrodynamic pressure has higher value when the exciting frequency is equal and lower than the fundamental frequency of the water in the tank. Similarly, the hydrodynamic pressure increases with the increase of width of the block for all exciting frequencies when the block is at the centre of tank. The left and right walls of tank have experienced different hydrodynamic pressure when the block is placed at off-centre. However, the increase in hydrodynamic pressure on nearest tank wall becomes insignificant after a certain value of the distance between the wall and the rigid block.

• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.929-935
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• 2018

This paper develops a flow control block for a hydraulic system of a tunnel boring machine. The flow control block is a necessary component to ensure stability in the operation of the hydraulic system. In order to know the pressure distribution of the flow control block, the flow analysis was performed using the ANSYS-CFX. It was confirmed that the pressure and flow rate were normally supplied to the hydraulic system even if one of the four ports of the flow control block was not operated. In order to evaluate the structural stability of the flow control block, structural analysis was performed using the ANSYS WORKBENCH. As a result, the safety factor of the flow control block is 1.54 and the structural stability is secured.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.639-648
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• 2005

Up to now, practical engineers applying simplicity value of rockfall block weight suggested in design manual without considering in-situ rockfall block weight which reflect joint characteristics. However, the size of rockfall block varies with joint spacing of discontinuities and influences over rockfall analysis results. In this paper, we estimate realistic rockfall block weight distribution using statistical invariances of joint spacing derived from scan-line survey result. And, we study whether this distribution is applicable in practical rockfall analysis directly. As the results of this study, rockfall analysis results that using rockfall block weight distribution estimated from scan-line survey show resonable and realistic outcomes.

• The Korean Journal of Pain
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• v.34 no.4
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• pp.487-500
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• 2021

Background: Although the erector spinae plane block has been used in various truncal surgical procedures, its clinical benefits in patients undergoing spinal surgery remain controversial. The aim of this meta-analysis was to evaluate the clinical benefits of erector spinae plane block in patients undergoing spinal surgery. Methods: We searched the Cochrane Library, PubMed, EMBASE, and China National Knowledge Infrastructure for randomized controlled trials comparing the erector spinae plane block with a nonblocked control for spinal surgery. Results: Twelve studies encompassing 696 subjects were included in our systematic review and meta-analysis. We found that the erector spinae plane block decreased postoperative pain scores and opioid consumption in the postoperative and intraoperative periods. Moreover, it prolonged the time to the first rescue analgesic, reduced the number of patients who required rescue analgesia, and lowered the incidence of postoperative nausea and vomiting. However, it did not exhibit efficacy in decreasing the incidence of urinary retention and itching or shortening the length of hospital stays, or the time to first ambulation. Conclusions: Erector spinae plane block improves analgesic efficacy among patients undergoing spinal surgery compared with nonblocked controls; however, there is insufficient evidence regarding the benefits of erector spinae plane block for rapid recovery.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.59-67
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• 1999

The mass concrete structures are generally constructed in an incremental manner by deviding the whole structures by a series of many blocks. The temperature and stress distributions of any specific block are continuously affected by the blocks placed before and after the specific block. For an accurate analysis of mass concrete structures, the sequence of all the blocks must be accordingly considered including the change of material properties with time for those blocks considered. The purpose of this study is to propose a realistic analysis method which can take into account not only the influence of the sequence, time interval and size of concrete block placement on the temperatures and stresses, but also the change of material properties with time. It is seen from this study that the conventional simplified analysis, which neglects material property changes of some blocks with time and does not consider the effect of adjacent blocks in the analysis, may yield large discrepancies in the temperature and stress distributions of mass concrete structures. This study gives a method to choose the minimum number of blocks required to obtain reasonably accurate results in analysis. The study provides a realistic method which can determine the appropriate size and time interval of block placement, and can be efficiently used in the design and construction of mass concrete structures.

• International Journal of Concrete Structures and Materials
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• v.9 no.1
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• pp.21-33
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• 2015

This study aimed to present a reinforced concrete block system that reduces the flange thickness of the existing form block used in new buildings and optimizes the web form, and can thus capable of being used in the seismic retrofit of new and existing buildings. By conducting a compression test and finite element analysis based on the block and grouted concrete strength, it attempted to determine the compression capacity of the form block that can be used in new construction and seismic retrofit. As a result, the comparison of the strength equation from Architectural Institute of Japan to the prism compression test showed that the mortar coefficient of 0.55 was suitable instead of 0.75 recommended in the equation. The stress-strain relation of the block was proposed as a bi-linear model based on the compression test result of the single form block. Using the proposed model, finite element analysis was conducted on the prism specimens, and it was shown that the proposed model predicted the compression behavior of the form block appropriately.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.863-869
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• 2013

In this paper, we compared and analyzed for safety 1.2m rectangular anchor block and arch-type root anchor block. First, numerical analysis was performed three-dimensional nonlinear method by numerical model test using finite element analysis program "Visual FEA". Then, measure displacement of the surface of the earth after construct each anchor block at 14M electric pole and increase loads through field verification tests for safety evaluation.

• The Korean Journal of Pain
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• v.34 no.3
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• pp.271-287
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• 2021

Background: Postoperative pain management is crucial for patients undergoing total knee arthroplasty (TKA). There have been many recent clinical trials on post-TKA peripheral nerve block; however, they have reported inconsistent findings. In this meta-analysis, we aimed to comprehensively analyze studies on post-TKA analgesia to provide evidence-based clinical suggestions. Methods: We performed a computer-based query of PubMed, Embase, the Cochrane Library, and the Web of Science to retrieve related articles using neurothe following search terms: nerve block, nerve blockade, chemodenervation, chemical neurolysis, peridural block, epidural anesthesia, extradural anesthesia, total knee arthroplasty, total knee replacement, partial knee replacement, and others. After quality evaluation and data extraction, we analyzed the complications, visual analogue scale (VAS) score, patient satisfaction, perioperative opioid dosage, and rehabilitation indices. Evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation approach. Results: We included 16 randomized controlled trials involving 981 patients (511 receiving peripheral nerve block and 470 receiving epidural block) in the final analysis. Compared with an epidural block, a peripheral nerve block significantly reduced complications. There were no significant between-group differences in the postoperative VAS score, patient satisfaction, perioperative opioid dosage, and rehabilitation indices. Conclusions: Our findings demonstrate that the peripheral nerve block is superior to the epidural block in reducing complications without compromising the analgesic effect and patient satisfaction. Therefore, a peripheral nerve block is a safe and effective postoperative analgesic method with encouraging clinical prospects.