• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.60
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• pp.11-22
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• 2000

The main objective of this research is to analyze an order point and an order quantity of a distribution center and each branch to attain a target service level in multi-level inventory distribution system. In case of product item, we use the item with low volume of average monthly demand. Under the continuous review method, the distribution center places a particular order quantity to an outside supplier whenever the level of inventory reaches an order point, and receives the order quantity after elapsing a certain lead time. Also, each branch places an order quantity to the distribution center whenever the level of inventory reaches an order point, and receives the quantity after elapsing a particular lead time. When an out of stock condition occurs, we assume that the item is backordered. For considering more realistic situations, we use generic type of probability distribution of lead times. In the variable lead time model, the actually achieved service level is estimated as the expected service level. Therefore, this study focuses on the analysis of deciding the optimal order point and order quantity to achieve a target service level at each depot as a expected service level, while the system-wide inventory level is minimized. In addition, we analyze the order level as a maximum level of inventory to suggest more efficient way to develop the low demand item model.

• Smart Structures and Systems
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• v.23 no.2
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• pp.207-214
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• 2019

Achieving a pervious concrete (PC) with appropriate physical and mechanical properties used in pavement have been strongly investigated through the use of different materials specifically from the global waste materials of the populated areas. Discarded tires and the rubber tire particles have been currently manufactured as the recycled waste materials. In the current study, the combination of polymer, silica fume and rubber aggregates from rubber tire particles have been used to obtain an optimized PC resulting that the PC with silica fume, polymer and rubber aggregate replacement to mineral aggregate has greater compressive and flexural strength. The related flexural and compressive strength of the produced PC has been increased 31% and 18% compared to the mineral PC concrete, also, the impact resistance has been progressed 8% compared to the mineral aggregate PC and the permeability with Open Graded Fraction Course standard (OGFC). While the manufactured PC has significantly reduced the elasticity modulus of usual pervious concrete, the impact resistance has been remarkably improved.

• Structural Monitoring and Maintenance
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• v.6 no.2
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• pp.85-101
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• 2019

The effects of foundation scour depth and riverbed condition on the natural frequencies of a typical cross-river integral abutment bridge have been studied. The conventional operational modal analysis technique has been employed in order to extract the modal properties of the bridge and the results have been used in the Finite Element (FE) model updating procedure. Two tests have been carried out in two different levels of water and wet condition of the riverbed. In the first test, the riverbed was in dry condition for two subsequent years and the level of water was 10 meter lower than the natural riverbed. In the second test, the river was opened to water flow from the upstream dam and the level of water was 2 meter higher than the natural riverbed. The results of these two tests have also been used in order to find to what extend the presence of water flow in the river and saturation of the surrounding soil affect the bridge natural frequencies. Finally, the updated FE model of the bridge has been applied in a series of parametric analyses incorporating the effect of piles' relative scour depth on the bridge natural frequency of the first four vibration modes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.2
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• pp.15-23
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• 2021

Most of the open-source decision tree algorithms are based on three splitting criteria (Entropy, Gini Index, and Gain Ratio). Therefore, the advantages and disadvantages of these three popular algorithms need to be studied more thoroughly. Comparisons of the three algorithms were mainly performed with respect to the predictive performance. In this work, we conducted a comparative experiment on the splitting criteria of three decision trees, focusing on their interpretability. Depth, homogeneity, coverage, lift, and stability were used as indicators for measuring interpretability. To measure the stability of decision trees, we present a measure of the stability of the root node and the stability of the dominating rules based on a measure of the similarity of trees. Based on 10 data collected from UCI and Kaggle, we compare the interpretability of DT (Decision Tree) algorithms based on three splitting criteria. The results show that the GR (Gain Ratio) branch-based DT algorithm performs well in terms of lift and homogeneity, while the GINI (Gini Index) and ENT (Entropy) branch-based DT algorithms performs well in terms of coverage. With respect to stability, considering both the similarity of the dominating rule or the similarity of the root node, the DT algorithm according to the ENT splitting criterion shows the best results.

• Advances in concrete construction
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• v.11 no.3
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• pp.219-229
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• 2021

In recent years, geopolymer cements, have gained significant attention as an environmental-friendly type of cement. In this experimental research, effects of different alkaline activator solutions and variations of associated parameters, including time of addition, concentration, and weight ratio, on the mechanical strengths of Granulated Ground Blast Furnace Slag (GGBFS)-based Geopolymer Concrete (GPC) were investigated. Investigation of the effects of simultaneous usage of KOH and NaOH solutions on the tensile and flexural strengths of GGBFS-based GPC, and the influence of NaOH solution addition time delay on the mechanical strengths is among the novel aspects investigated in this research. four series of mix designs and corresponding specimen testing is conducted to study different parameters of the active alkali solutions on GPC mechanical strengths. The results showed that addition of NaOH to the mix after 3 min of mixing KOH and Na2SiO3 with dry components (1/3 of the total mixing duration) resulted in the highest compressive, tensile and flexural strengths amongst other cases. Moreover, increasing the KOH concentration up to 12 M resulted in the highest compressive strength, while weight ratio of 1.5 for Na2SiO3/KOH was the optimum value to achieve highest compressive strengths.

• ALGAE
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• v.37 no.3
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• pp.205-211
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• 2022

The trend in naming genera based almost exclusively on molecular data, and not on morphological diagnostic characters, is increasing. In bifurcating phylogenetic trees generic cut-offs are arbitrary, but at the bare minimum nomenclatural changes should be supported by multiple phylogenetic methodologies using appropriate models for all the various gene partitions, strong support with all branch support methods, and should also result in adding to our knowledge of the interrelationships of taxa. We believe that a recent taxonomic treatment of the genus Pyropia (Yang et al. 2020) into several genera is unwarranted. We reanalysed the data presented in the recent article, using additional phylogenetic methods. Our results show that many of the newly established genera are not well supported by all methods, and the new circumscription of the genus Pyropia renders it unsupported. We also tested additional outgroups, which were previously suggested as sister to Pyropia, but this did not substantially change our conclusions. These generic nomenclatural changes of the previously strongly supported genus Pyropia, do not shed light on the evolution of this group and have serious consequences in these commercially important algae, that are also governed by a plethora of regulation and by-laws that now need to be amended. We suggest that the over-splitting of groups based only on poorly produced and modestly supported phylogenies should not be accepted and that the genus Pyropia sensu Sutherland et al. (2011) be restored.

• Steel and Composite Structures
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• v.44 no.6
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• pp.867-882
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• 2022

Predicting the compressive strength of concrete (CSoC) is of high significance in civil engineering. The CSoC is a highly dependent and non-linear parameter that requires powerful models for its simulation. In this work, two novel optimization techniques, namely evaporation rate-based water cycle algorithm (ER-WCA) and equilibrium optimizer (EO) are employed for optimally finding the parameters of a multi-layer perceptron (MLP) neural processor. The efficiency of these techniques is examined by comparing the results of the ensembles to a conventionally trained MLP. It was observed that the ER-WCA and EO optimizers can enhance the training accuracy of the MLP by 11.18 and 3.12% (in terms of reducing the root mean square error), respectively. Also, the correlation of the testing results climbed from 78.80% to 82.59 and 80.71%. From there, it can be deduced that both ER-WCA-MLP and EO-MLP can be promising alternatives to the traditional approaches. Moreover, although the ER-WCA enjoys a larger accuracy, the EO was more efficient in terms of complexity, and consequently, time-effectiveness.

• Structural Engineering and Mechanics
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• v.88 no.3
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• pp.263-271
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• 2023

Base isolation is a widely used technique for the seismic control of structures as it reduces the structural seismic demand. However, displacement of the isolation layer is not economically feasible in congested urban areas. To resolve the issue, an innovative system is proposed here to isolate both horizontally at the base and vertically in the upper portion of the structure. A simplified linear three degree-of-freedom (3DOF) model of the system that considers the mass and stiffness ratios of the substructure has been introduced and analyzed in MATLAB by spectrum analysis. The 3DOF model results revealed that, when the period of the soft substructure reaches 2.5 times that of the stiff substructure, the isolation and the lower substructure responses decrease by 65% and 51%, respectively. Time-history analysis of a MDOF system at three frequency ratios under a wide range of ground motions indicated that, at the expense of accepting a certain large drift by the soft substructure in the upper portion of the structure, base isolation displacement can be decreased by 10%.

• Advances in nano research
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• v.16 no.6
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• pp.615-622
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• 2024

This study investigates the impact of educational management on the performance of scholars in the field of nano/micro-level composites. The objective is to understand how effective management strategies can enhance the academic achievements and research outcomes of students specializing in this advanced area of materials science. Through a combination of qualitative and quantitative methodologies, data was collected from various educational institutions renowned for their programs in nano/micro-level composites. Our results indicate that tailored educational management practices significantly improve student performance. Key strategies identified include personalized mentorship programs, interdisciplinary collaboration opportunities, and access to state-of-the-art laboratory facilities. Institutions that implemented these practices observed a marked increase in the quality and quantity of research outputs, higher student satisfaction rates, and improved post-graduation employment prospects in relevant industries. Furthermore, the study highlights the importance of continuous professional development for educators to stay abreast of the latest advancements in nano/micro-level composites. By fostering an environment of innovation and support, educational management can play a crucial role in shaping the next generation of researchers and professionals in this cutting-edge field. These findings underscore the necessity of strategic educational management in optimizing the academic and professional trajectories of scholars in nano/micro-level composites, ultimately contributing to advancements in technology and industry applications.

• Journal of Yeungnam Medical Science
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• v.41 no.3
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• pp.179-187
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• 2024

Myofascial pain syndrome (MPS) is a common musculoskeletal disorder characterized by muscle pain, tenderness, and trigger points. Ultrasonography has emerged as a key tool for diagnosing and treating MPS owing to its ability to provide precise, minimally invasive guidance. This review discusses the use of ultrasonography in various approaches to evaluate and manage MPS. Studies have shown that shear-wave sonoelastography can effectively assess muscle elasticity and offer insights into trapezius stiffness in patients with MPS. Ultrasound-guided interfascial hydrodissection, especially with visual feedback, has demonstrated effectiveness in treating trapezius MPS. Similarly, ultrasound-guided rhomboid interfascial plane blocks and perimysium dissection for posterior shoulder MPS have significantly reduced pain and improved quality of life. The combination of extracorporeal shockwave therapy with ultrasound-guided lidocaine injections has been particularly successful in reducing pain and stiffness in trapezius MPS. Research regarding various guided injections, including dry needling, interfascial plane blocks, and fascial hydrodissection, emphasizes the importance of ultrasonography for accuracy and safety. Additionally, ultrasound-guided delivery of local anesthetics and steroids to the quadratus lumborum muscle has shown lasting pain relief over a 6-month period. Overall, these findings highlight the pivotal role of ultrasonography in the assessment and treatment of MPS.