• Elastomers and Composites
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• v.43 no.2
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• pp.88-103
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• 2008

This study was purposed to investigate the effects of surfactants and fillers on physical properties of hydrophilic polyvinylsiloxane dental impression materials (PVS). Incorporation of surfactants enhanced the hydrophilicity of the PVS, however, it induced increased viscosity and permanent deformation ratio, delayed setting, and decreased tensile strength. At high concentrations of surfactant, the tensile strength was observed to decrease significantly due to the internal pore formation. Especially, the hydrophilicity of the PVS was significantly enhanced with the addition of Silwet L-77. However, the viscosity, strain in compression, pore formation, and setting time increased whereas the elastic recovery rate and strength remarkably decreased. The PVS dental materials containing Span 20 showed the lowest degree of viscosity increase, delayed setting, pore formation, and hydrophilicity. The delayed setting, pore formation, and strength decrease caused by the incorporation of surfactant were improved by substituting the crystalline quartz filler with diatomaceous earth while the contact angle of PVS dental materials increased.

• Journal of Power Electronics
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• v.10 no.5
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• pp.548-554
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• 2010

In this paper, a 1.5 kW Interior Permanent Magnet Synchronous Generator (IPMSG) with a power conditioner for the grid integration of a variable-speed wind turbine is developed. The power-conditioning system consists of a series-type 12-pulse diode rectifier powered by a phase shifting transformer and then cascaded to a PWM voltage source inverter. The PWM inverter is utilized to supply sinusoidal currents to the utility line by controlling the active and reactive current components in the q-d rotating reference frame. While the q-axis active current of the PWM inverter is regulated to follow an optimized active current reference so as to track the maximum power of the wind turbine. The d-axis reactive current can be adjusted to control the reactive power and voltage. In order to track the maximum power of the wind turbine, the optimal active current reference is determined by using a simple MPPT algorithm which requires only three sensors. Moreover, the phase angle of the utility voltage is detected using a simple electronic circuit consisting of both a zero-crossing voltage detecting circuit and a counter circuit employed with a crystal oscillator. At the generator terminals, a passive filter is designed not only to decrease the harmonic voltages and currents observed at the terminals of the IPMSG but also to improve the generator efficiency. The laboratory results indicate that the losses in the IPMSG can be effectively reduced by setting a passive filter at the generator terminals.

• The Journal of Art Theory & Practice
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• no.5
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• pp.83-107
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• 2007

The continuous struggle to establish virtual reality on the stage during the history of Western Theater has been centered upon the development of scenographic setting and devices. It began with the Classical Greek drama where the place of performance became separated from the place of the audience. These two places were united as the orchestra - the place of the Dionysiac festival in the earliest stage of the Greek theater. And the skene, once a storage building outside the theatrical area, became an essential factor of the scenic space to provide illusion of the other world where the actors dwell. As a natural consequence it followed the structural change of Roman theater where the stage became a high and wide platform and the skene converted into the permanent stone scaenae frons. Such a tradition of the Classical theater was revived in Italian Renaissance and Baroque theater, which succeeded Vitruvius' concept of scaenographia as well as the vestiges of Imperial Roman theater. The cases of Serlio, Palladio, and Andrea Pozzo reveal the way how Western theater conjured the fictional space by traditional representational scenery, including architectural background setting and painted devices. It resulted in the physical and emotional division of actors' space and audience's space. The rejection of representational scenery upon the stage by avant garde artists like Edward Gordon Craig in the early years of the twentieth century should be interpreted as an attempt to recover an emotional attachment of actors and the audience, which was the case of Greek antiquity. This new scenogrpahic endeavor in modern theater is to challenge the main purpose of traditional scaenae frons to establish the boundary of the illusional 'scene' of performance where the audience should remain as passive spectators, and instead, to try to unite the action of actors and the audience upon the stage as a 'place'.

• Restorative Dentistry and Endodontics
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• v.45 no.4
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• pp.50.1-50.11
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• 2020

Objectives: In this study, we investigated the potential of amoxicillin-loaded polymeric microspheres to be delivered to tooth root infection sites via a bioactive reparative cement. Materials and Methods: Amoxicillin-loaded microspheres were synthesized by a spray-dray method and incorporated at 2.5% and 5% into a mineral trioxide aggregate cement clinically used to induce a mineralized barrier at the root tip of young permanent teeth with incomplete root development and necrotic pulp. The formulations were modified in liquid:powder ratios and in composition by the microspheres. The optimized formulations were evaluated in vitro for physical and mechanical eligibility. The morphology of microspheres was observed under scanning electron microscopy. Results: The optimized cement formulation containing microspheres at 5% exhibited a delayed-release response and maintained its fundamental functional properties. When mixed with amoxicillin-loaded microspheres, the setting times of both test materials significantly increased. The diametral tensile strength of cement containing microspheres at 5% was similar to control. However, phytic acid had no effect on this outcome (p > 0.05). When mixed with modified liquid:powder ratio, the setting time was significantly longer than that original liquid:powder ratio (p < 0.05). Conclusions: Lack of optimal concentrations of antibiotics at anatomical sites of the dental tissues is a hallmark of recurrent endodontic infections. Therefore, targeting the controlled release of broad-spectrum antibiotics may improve the therapeutic outcomes of current treatments. Overall, these results indicate that the carry of amoxicillin by microspheres could provide an alternative strategy for the local delivery of antibiotics for the management of tooth infections.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.204-209
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• 2003

A 9-year old boy visited Department of Pediatric dentistry, Chonbuk National University Hospital due to unstable occlusion. He had permanent 1st molars destructed severely by dental caries and lost vertical stop. He could not occlude in the same position on closing of the jaw since he could not find his centric occlusion. The treatment plan was made, which was oral rehabilitation with crown restorations on permanent 1st molars based on clinical and radiographic examinations and centric relation of the jaw. Treatment plan consisted of endodontic treatment, crown lengthening and restoration of the occlusal vertical dimension (OVD) with gold crown by 3mm-increase of OVD. After endodontic and periodontal treatments, temporary crowns made of acrylic resin were set for assessment of tolerance to an increased OVD. After a month for tolerance, final prosthetics were made and set temporarily. In a month, gold crowns were set finally. Immediately after setting, the patient showed anterior open bite, but at the appointment after 4 months, he showed normal overjet, overbite and stable occlusion.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.15 no.2
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• pp.87-91
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• 2004

Background and Objectives : Temporary vocal fold injection is not only performed to restore the laryngeal function in temporary unilateral vocal fold paralysis or paresis, but also performed as a test injection prior to the permanent injection. Gelfoam has been safely used for the past several decades for the temporary vocal fold augmentation. Recently, we found a new material, called Radieses Lite, may be used as a temporary injection material. Material and Methods : We report preliminary results of 11 patients who had Radiesse Lite injection with a variety of pathologies. Results : Based on the results from the 6 patients who completed follow-up, the duration of effectiveness of Radiesse Lite seems to be from 2 to 3 months depending on the injection amount. Radiesse Lite satisfies several requirements of the ideal temporary vocal fold injection material in terms of injectability, convenience, duration of effectiveness and safety. Conclusion : The authors concluded that Radiesse Lite might be a good option for temporary vocal fold injection especially in the office setting.

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.215-225
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• 2011

In this paper, a buck DC-DC bridge converter is used as a power factor correction (PFC) converter for feeding a voltage source inverter (VSI) based permanent magnet brushless DC motor (PMBLDCM) drive. The front end of the PFC converter is a diode bridge rectifier (DBR) fed from single phase AC mains. The PMBLDCM is used to drive the compressor of an air conditioner through a three-phase voltage source inverter (VSI) fed from a variable voltage DC link. The speed of the air conditioner is controlled to conserve energy using a new concept of voltage control at a DC link proportional to the desired speed of the PMBLDC motor. Therefore, VSI operates only as an electronic commutator of the PMBLDCM. The current of the PMBLDCM is controlled by setting the reference voltage at the DC link as a ramp. The proposed PMBLDCM drive with voltage control-based PFC converter was designed and modeled. The performance is simulated in Matlab-Simulink environment for an air conditioner compressor load driven through a 3.75 kW, 1500 rpm PMBLDC motor. To validate the effectiveness of the proposed speed control scheme, the evaluation results demonstrate improved efficiency of the complete drive with the PFC feature in a wide range of speed and input AC voltage.

• Journal of Korean Neurosurgical Society
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• v.55 no.6
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• pp.383-386
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• 2014

Objective : Symptomatic thoracic disc herniation often requires prompt surgical treatment to prevent neurological deterioration and permanent deficits. Anterior approaches offer direct visualization and access to the herniated disc and anterior dura but require access surgeons and are often associated with considerable postoperative pain and pulmonary complications. A disadvantage with using posterior approaches in the setting of central calcified thoracic disc herniation however, has been the limited visualization of anterior dura and difficulty to accurately assess the extent of decompression. Methods : We report our experience with intraoperative ultrasound (US) guidance during a modified posterior transpedicular approach for removal of a central calcified thoracic disc herniation with a review of pertinent literature. Results : The herniated thoracic disc was successfully removed with posterior approach with the aid of intraoperative US. The patient had significant neurological improvement at three months follow-up. Conclusion : Intraoperative ultrasound is a simple yet valuable tool for real-time imaging during transpedicular thoracic discectomy. Visualization provided by intraoperative US increases the safety profile of posterior approaches and may make thoracotomy unnecessary in a selected group of patients, especially when a patient has existing pulmonary disease or is otherwise not medically fit for the transthoracic approach.

• Journal of Environmental Impact Assessment
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• v.11 no.3
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• pp.223-230
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• 2002

The rapid impact assessment matrix (RIAM) might be a new tool for performance of an environmental impact assessment (EIA), comparing with many traditional methods of EIA, which have produced large reports setting out the subjective judgement reached by the assessors. The main criticisms of E1A are in part a natural result of the traditional method used. RIAM uses a structured matrix to allow for such judgement, both subjective and those based on quantitative data, to be made on a like-by-like basis, and provided a transparent and permanent record of the judgement made. Also, the computerized RIAM system using software program allows for the matrix to be shown in graphical form, which greatly enhances the clarity of the results produced by this method. RIAM provides a system by which development options and scenarios can be rapidly evaluated. To illustrate the use of RIAM, an example from an EIA study using application of scoping by assessment criteria in Environmental Impact Regulation of Korea was given. The criteria that might be used to evaluation EIA methods, and how RIAM measures up against these criteria, are discussed.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.280-286
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• 1998

This paper proposes a novel method to reduce the torque ripple due to the non-ideality of the current sensing parts in vector-controlled inverter-fed AC motor drive systems. For PMSM(Permanent Magnet Synchronous Motor), motor output torque equations are derived in terms of their offset voltages and different voltage transducing gains. And the effects of phase current errors on motor torque are analyzed for both salient PMSM and non-salient PMSM. The proposed method can eliminate the torque ripple by nulling the offset voltages and setting the voltage transducing gains to the same value. To verify the proposed method, digital simulations are carried out for non-salient PMSM.