• Coupled systems mechanics
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• v.11 no.5
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• pp.439-458
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• 2022

Over-coating is one of the most popular engineering practices to strengthen Reinforced Concrete (RC) structures, due to the relative quickness and ease of construction. It consists of an external coat bonded to the outer surface of the structural RC element, either by the use of chemical adhesives, mechanical anchor bolts or simply mortar injection. In contrast to these constructive advantages, the numerical estimation of the bearing capacity of the strengthened reinforced concrete element is still complicated, not only for the complexity of modelling a flexible membrane or plate attached to a quasi-rigid solid, but also for the difficulties that raise of simulating any potential delamination between both materials. For these reasons, the standard engineering calculations used in the practice remain very approximated and clumsy. In this work, we propose the formulation of a new 2D solid-layer finite element capable to link a solid body with a flexible thin layer, as it were the "skin" of the body, allowing the potential delamination between both materials. In numerical terms, this "skin" element is intended to work as a transitional region between a solid body (modelled with a classical formulation of a standard quadrilateral four-nodes element) and a flexible coat layer (modelled with cubic beam element), dealing with the incompatibility of Degrees-Of-Freedom between them (two DOF for the solid and three DOF for the beam). The aim of the solid-layer element is to simplify the mesh construction of the strengthened RC element being aware of two aspects: a) to prevent the inappropriate use of very small solid elements to simulate the coat; b) to improve the numerical estimation of the real bearing capacity of the strengthened element when the coat is attached or detached from the solid body.

• Coupled systems mechanics
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• v.12 no.6
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• pp.481-501
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• 2023

Over-coating is one of the most popular engineering practices to strengthen Reinforced Concrete (RC) structures, due to the relative quickness and ease of construction. It consists of an external coat bonded to the outer surface of the structural RC element, either by the use of chemical adhesives, mechanical anchor bolts or simply mortar injection. In contrast to these constructive advantages, the numerical estimation of the bearing capacity of the strengthened reinforced concrete element is still complicated, not only for the complexity of modelling a flexible membrane or plate attached to a quasi-rigid solid, but also for the difficulties that raise of simulating any potential delamination between both materials. For these reasons, the standard engineering calculations used in the practice remain very approximated and clumsy. In this work, we propose the formulation of a new 2D solid-layer finite element capable to link a solid body with a flexible thin layer, as it were the "skin" of the body, allowing the potential delamination between both materials. In numerical terms, this "skin" element is intended to work as a transitional region between a solid body (modelled with a classical formulation of a standard quadrilateral four-nodes element) and a flexible coat layer (modelled with cubic beam element), dealing with the incompatibility of Degrees-OfFreedom between them (two DOF for the solid and three DOF for the beam). The aim of the solid-layer element is to simplify the mesh construction of the strengthened RC element being aware of two aspects: a) to prevent the inappropriate use of very small solid elements to simulate the coat; b) to improve the numerical estimation of the real bearing capacity of the strengthened element when the coat is attached or detached from the solid body.

• Korean Circulation Journal
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• v.54 no.3
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• pp.126-137
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• 2024

Background and Objectives: The impact of off-hours admission (such as weekends, nighttime, and non-working hours) vs. regular hours (weekdays and daytime working hours) on the mortality risk of patients undergoing surgery for type A aortic dissection (TAAD) repair is still uncertain. To address this uncertainty, we undertook a comprehensive systematic review and meta-analysis. We aimed to assess the potential link between off-hours admission and the risk of mortality in patients undergoing TAAD repair surgery. Methods: We conducted a thorough search of the PubMed, Embase, and Cochrane Library databases, covering the period from their inception to May 20, 2023. Our inclusion criteria encompassed all studies that examined the potential relationship between off-hour admission and mortality in individuals who had undergone surgery for TAAD repair. The odds ratios (ORs) were extracted and combined utilizing a random effects model for our synthesis. Results: Nine studies with 16,501 patients undergoing TAAD repair surgery were included in the meta-analysis. Overall, patients who underwent surgery during the weekend had higher in-hospital mortality (pooled OR, 1.41; 95% confidence interval [CI], 1.14-1.75; p=0.002) than those treated on weekdays. However, the mortality risks among patients who underwent TAAD surgery during nighttime and non-working hours were not significantly elevated compared to daytime and working hours admission. Conclusions: Weekend surgery for TAAD was associated with a higher in-hospital mortality risk than weekday surgery. However, further studies are warranted to identify and develop strategies to improve the quality of round-the-clock care for patients with TAAD.

• Journal of Mechanical Science and Technology
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• v.16 no.8
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• pp.1053-1063
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• 2002

This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.

• Journal of Power Electronics
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• v.12 no.1
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• pp.145-156
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• 2012

These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynamic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.6_2
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• pp.585-592
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• 2013

CBIR is an effective tool to search and extract image contents in a large remote sensing image database queried by an operator or end user. However, as imaging principles are different by sensors, their visual representation thus varies among image modality type. Considering images of various modalities archived in the database, image modality difference has to be tackled for the successful CBIR implementation. However, this topic has been seldom dealt with and thus still poses a practical challenge. This study suggests a cross modality CBIR (termed as the CM-CBIR) method that transforms given query feature vector by a supervised procedure in order to link between modalities. This procedure leverages the skill of analyst in training steps after which the transformed query vector is created for the use of searching in target images with different modalities. Current initial results show the potential of the proposed CM-CBIR method by delivering the image content of interest from different modality images. Despite its retrieval capability is outperformed by that of same modality CBIR (abbreviated as the SM-CBIR), the lack of retrieval performance can be compensated by employing the user's relevancy feedback, a conventional technique for retrieval enhancement.

• Journal of the Korean Chemical Society
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• v.58 no.2
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• pp.193-197
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• 2014

Dibenzo-18-crown-6, dibenzo-21-crown-7 and dihydroxy dibenzo-18-crown-6 were synthesized by Bayer-Villiger oxidation strategy. Dibenzo-18-crown-6 and dibenzo-21-crown-7 could be synthesized through a three-step protocol starting from salicylaldehyde. Salicylaldehyde was reacted with bis-(2-chloroethyl)ether using $K_2CO_3$ in acetonitrile to link the two phenolic groups with the oxyethylene bridge followed by conversion of the formyl group to the hydroxy group via a Baeyer-Villiger reaction and finally linking the two phenolic group with appropriate oxyethylene bridge. The two target crown ethers were obtained in overall yield, 24% and 30%, respectively. This method has a great potential for synthesis of symmetrical as well as unsymmetrical dibenzo crowns with varying oxyethylene bridges. Baeyer-Villiger oxidation could be used to prepare dihydroxy derivative of dibenzo-18-crown-6 through acetylation of dibenzo-18-crown-6 followed by Baeyer-Villiger oxidation. The Baeyer-Villiger oxidation could be substantially accelerated using trifluoroacetic acid.

• Asia pacific journal of information systems
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• v.6 no.2
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• pp.107-124
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• 1996

This research studied future directions of Internet technology toward supporting group decision making. From the previous research, this study classified requirements of group decision support systems into three categories which are information transfer, information provision, and communication control. For each of the category, this study analyzed the limits of current Internet functions. Next, this research discussed technological solutions, for each of the OSI 7 layers, toward supporting group decision making. Additional functions in Internet which are required for group supporting are tracing communications, application dependent coding, selection of communication modes, and security handling. For high speed data communication in Internet, this research discussed the potential of cell-switching technology for the lower level link in Internet. The conclusions of this research can be used for designing future group decision support systems and development of Internet.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.2 no.1
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• pp.66-87
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• 1974

It is the prime importance of the information and the reference-librarians to better understand the communication functions of the library since they are the ones to whom the library users come first with their informational needs. Reference librarians often have the problem of providing information to those who may have little experience with, or interest in the library. There is also a problem of finding out what the person really wants, not what he says he wants. Therefore, the interaction between the librarian and the user involves a highly complex activity of communication with each other even before the actual search begins. Reference librarians cannot perform to any degree of success without comprehension of the general patterns and processes of communication in information seeking. Nonverbal as well as verbal transmittal process on the part of both librarians and patrons should not be overlooked. Some of the difficulties and barriers of library communication are brought so that possible cures and improvement may be sought. The basic purpose of the reference interview through which this interpersonal communication takes place is for the reference specialist to enable to link the needs of the patron with potential resource of the library. The writer firmly believes that this importance of the process be taught as well as the materials in reference service regardless of the level of the course offered in library science department.

• Journal of Society of Preventive Korean Medicine
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• v.11 no.1
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• pp.101-108
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• 2007

In the Study of Poem in Health-Preservation, the results were as follows : Though poetry as therapy is a relatively new development in the expressive arts, it is as old as the first chants sung around the tribal fires of primitive peoples. For many centuries the link between poetry and medicine remained obscure. The chant/song/poem is what heals the heart and soul and is used for health-Preservation and the well-being. Poetry Therapy began to flourish in the hands of professional in various disciplines, including rehabilitation, education, library science, recreation, and the creative arts. Mental health professional were exploring the therapeutic value of literary materials, especially of poetry. Their contribution to the emerging discipline was two-fold : 1) emphasis on the evocative value of literature, particularly poetry; and 2) recognition of the beneficial potential of having clients write either their response to poems written by others or original material, drawing on the clients' own experiences and emotions. Especially in Oriental Medicine, the therapy is based on controlling of Mind(心). And it is in harmony with Qi-circulation(氣-循環), so smoothing the circulation of meridians, strengthened Essential-material(精), Qi(氣), Sprit(神).