• Journal of Audiology & Otology
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• v.24 no.1
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• pp.24-28
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• 2020

Background and Objectives: Systemic steroid therapy (SST) and intratympanic steroid injection (ISI) have been the treatment of choice for sudden sensorineural hearing loss (SSNHL). We studied the effect of ISI administered at different intervals on hearing outcomes in patients with SSNHL. Subjects and Methods: We performed a retrospective study of 427 patients diagnosed with SSNHL at Bundang Jesaeng Hospital, of whom 51 patients with SSNHL who received SST and four ISIs were included in this study. Patients were treated with four ISIs either every day for 4 days (group 1) or at intervals (mean duration of interval: 2.21 days) (group 2). Hearing outcomes were evaluated using the pure-tone test before the injection and 14 days, 1 month, and 3 months after the final injection. Recovery rates were classified based on Siegel's criteria. Results: The amount of improvement was 27.67 dB (±20.45) in group 1 and 32.79 dB (±21.42) in group 2. However, there were no significant differences between the two groups (p= 0.714). The recovery rates based on Siegel's criteria were 18/27 (66.7%) and 16/24 (66.7%) in groups 1 and 2, respectively, with no significant difference (p=1.000). Considering only complete recoveries in hearing recovery, the recovery rates were 15/27 (55.6%) and 14/24 (58.3%) in groups 1 and 2, respectively, with no significant difference (p=0.842). Conclusions: There were no significant differences in hearing outcomes or recovery rates after ISI administration every day or at intervals of 2-3 days.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.209-223
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• 2001

At intrusion of upper anterior teeth in patient with periodontal defect, the use of three-piece base arch appliance for pure intrusion is required. To investigate the change of the center of resistance and of the distal traction force according to alveolar bone height at intrusion of upper anterior teeth using this appliance, three-dimensional finite element models of upper six anterior teeth, periodontal ligament and alveolar bone were constructed. At intrusion of upper anterior teeth by three-piece base arch appliance, the following conclusions were drawn to the locations of the center of resistance according to the number of teeth, the change of distal traction force for pure intrusion and the correlation to the change of vertical, horizontal location of the center of resistance according to alveolar bone loss. 1. When the axial inclination and alveolar bone height were normal, the anteroposterior locations of center of resistance of upper anterior teeth according to the number of teeth contained were as follows : 1) In 2 anterior teeth group, the center of located in the mesial 1/3 area of lateral incisor bracket. 2) In 4 anterior teeth group. the center of resistance was located in the distal 2/3 of the distance between the bracket of lateral incisor and canine. 3) In 6 anterior teeth group, the center of resistance was located in the central area of first premolar bracket .4) As the number of teeth contained in anterior teeth group increased, the center of resistance shifted to the distal side. 2. When the alveolar bone height was normal, the anteroposterior position of the point of application of the intrusive force was the same position or a bit forward position of the center of resistance at application of distal traction force for pure intrusion. 3. When intrusion force and the point of application of the intrusive force were fixed, the changes of distal traction force for pure intrusion according to alveolar bon loss were as follows :1) Regardless of the alveolar bone loss, the distal traction force of 2, 4 anterior teeth groups were lower than that of 6 anterior teeth group. 2) As the alveolar bone loss increased, the distal traction forces of each teeth group were increased. 4. The correlations of the vertical, horizontal locations of the center of resistance according to maxillary anterior teeth groups and the alveolar bone height were as follows : 1) In 2 anterior teeth group, the horizontal position displacement to the vortical position displacement of the center of resistance according to the alveolar bone loss was the largest. As the number of teeth increased, the horizontal position displacement to the vertical position displacement of the center of resistance according to the alveolar bone loss showed a tendency to decrease. 2) As the alveolar bone loss increased, the horizontal position displacement to the vertical position displacement of the center of resistance regardless of the number of teeth was increased.

• Journal of Cardiovascular Imaging
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• v.30 no.2
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• pp.140-141
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• 2022

• Investigative Magnetic Resonance Imaging
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• v.20 no.1
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• pp.36-43
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• 2016

Visualization of the tissue loss tangent property can provide distinct contrast and offer new information related to tissue electrical properties. A method for non-invasive imaging of the electrical loss tangent of tissue using magnetic resonance imaging (MRI) was demonstrated, and the effect of loss tangent was observed through simulations assuming a hyperthermia procedure. For measurement of tissue loss tangent, radiofrequency field maps ($B_1{^+}$ complex map) were acquired using a double-angle actual flip angle imaging MRI sequence. The conductivity and permittivity were estimated from the complex valued $B_1{^+}$ map using Helmholtz equations. Phantom and ex-vivo experiments were then performed. Electromagnetic simulations of hyperthermia were carried out for observation of temperature elevation with respect to loss tangent. Non-invasive imaging of tissue loss tangent via complex valued $B_1{^+}$ mapping using MRI was successfully conducted. Simulation results indicated that loss tangent is a dominant factor in temperature elevation in the high frequency range during hyperthermia. Knowledge of the tissue loss tangent value can be a useful marker for thermotherapy applications.

• ETRI Journal
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• v.20 no.3
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• pp.251-271
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• 1998

It is well known that if usage parameter control/network parameter control (UPC/NPC) functions are used together with a cell loss priority control scheme in ATM networks, the measurement phasing problem can occur. This makes it difficult for a network provider to define and commit the cell loss ratio as a QoS parameter. To solve the problem, we propose a new UPC/NPC algorithm. By using the proposed UPC/NPC algorithm, we can define the cell loss ratios for CLP = 0 and CLP = 0+1 cell streams without the measurement phasing problem under any conditions. We analyzed the performance of the proposed UPC/NPC algorithm. Using a discrete time model for the UPC/NPC architecture with a discrete-time semi-Markov process (DSMP) input model, we obtained the cell discarding probabilities of CLP = 0 and CLP = 0+1 cells streams and showed that more CLP = 0 cells are accepted compared to what was proposed in ITU-T.

• Journal of the Optical Society of Korea
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• v.16 no.1
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• pp.80-84
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• 2012

A high reflectance mirror, which has very low absorption and scattering loss, was coated onto a crystalline substrate by ion beam sputtering and then annealed at $450^{\circ}C$. We carefully selected the mirror coating material, and designed the high reflectance mirror, in order to avoid UV degradation which comes from the He-Ne plasma. We measured the surface roughness of the Zerodur substrate using phase shift interferometry and atomic force microscopy, and compared it with the TIS scattering of the mirror. The cavity ring-down method was used to measure the absorption of the mirror, and the thin film structure was correlated to its results. We also compared the optical properties of coated mirrors before and after annealing.

• Journal of Ocean Engineering and Technology
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• v.34 no.2
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• pp.55-65
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• 2020

A review of the 2nd generation of intact stability by the International Maritime Organization is performed. The main issues with the new stability criteria are reviewed. In particular, the physical background and related mathematical formulations of the pure loss of stability and parametric roll are summarized. Based on a literature review, benchmark calculation results for 17 different types of ships are discussed, and the final results are in excellent agreement with our physical expectations. Some relatively serious design problems are found in the application of the new stability criteria to sample ships built in Korea, and possible technical solutions are proposed, which have to be improved in the coming years.

• Transactions on Electrical and Electronic Materials
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• v.6 no.1
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• pp.1-5
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• 2005

Continued scaling of MOS devices requires the formation of the ultra shallow and very heavily doped junction. The simulation and experiment results show that the degradation of pMOS performance in logic and SRAM pMOS devices due to the excessive diffusion of the tail and a large amount of dose loss in the extension region. This problem comes from the high-temperature long-time deposition process for forming the spacer and the presence of fluorine which diffuses quickly to the $Si/SiO_{2}$ interface with boron pairing. We have studied the method to improve the pMOS performance that includes the low-energy boron implantation, spike annealing and device structure design using TCAD simulation.

• ETRI Journal
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• v.28 no.2
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• pp.247-249
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• 2006

In the development of a new wireless communications system, a versatile and accurate radio channel for indoor communications is needed. In particular, the investigation of radio transmission into buildings is very important. In this letter, we present an improved three-dimensional electromagnetic wave propagation prediction model for indoor wireless communications that takes into consideration building penetration loss. A ray tracing technique based on an image method is also employed in this study. Three-dimensional models can predict any complex indoor environment composed of arbitrarily shaped walls. A speed-up algorithm, which is a modified deterministic ray tube method, is also introduced for efficient prediction and computation.

• KIEE International Transactions on Power Engineering
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• v.4A no.2
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• pp.58-68
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• 2004

This paper presents an optimal routing algorithm (ORA) for maximizing voltage stability as well as for minimizing power loss in radial power systems. In the proposed ORA, a novel voltage stability index (VSI) for real-time assessment is newly introduced based on the conventional critical transmission path framework. In addition, the suggested algorithm can automatically detect the critical transmission paths resulting in voltage collapse when additional real or reactive loads are added. To implement an effective ORA, we have developed an improved branch exchange (IBE) method based on a loss calculation index and tie-branch power flow equations, which are suggested for real-time applications. The proposed algorithm has been tested with IEEE test systems as well as a large-scale power system in Korea to demonstrate its effectiveness and efficiency.