• Journal of Korean Ophthalmic Optics Society
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• v.15 no.2
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• pp.137-144
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• 2010

Purpose: This study was to evaluate the clinical performance of 1-Day disposable toric soft contact lenses (TSCL) and to compare the visual performance with glasses and TSCL. Methods: In a two-week investigation of 'prism ballast' designed TSCL, occular refractions in 15 (30 eyes) healthy subjects were within the range of -2.75 D TO -8.00 D spherical power and -0.75 DC to -2.25 DC cylinderical power (with-the-rule). Subjects were assessed the clinical performance (orientation, centration, movement, tightness, rotation recovery, symptoms) of TSCL and compared binocular vision and contrast sensitivity with corrected glasses and TSCL at initial and two-week follow-up visits. Results: The prism-ballast design TSCL achieved better orientation, rotation recovery and symptoms over 2 week period. There was no statistically significant difference between spectacles and TSCL with respect to measuring binocular vision and contrast sensitivity. Conclusions: The clinical performance was good with prism-ballast design toric soft contact lenses. Evaluation of binocular vision and contrast sensitivity did not show the differences between spectacles and TSCL correction. This study suggests that TSCL wearers can be achieved similar visual performance for spectacles wearers.

• Geophysics and Geophysical Exploration
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• v.25 no.1
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• pp.26-37
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• 2022

Recently, multiple methods using small aircraft for geophysical exploration have been suggested as a result of the development of information and communication technology. In this study, we introduce the hybrid unmanned aircraft electromagnetic system of the Korea Institute of Geosciences and Mineral resources, which is under development. Additionally, data processing and interpretation methods are suggested via the analysis of datasets obtained using the system under development to verify the system. Because the system uses a three-component receiver hanging from a drone, the effects of rotation on the obtained data are significant and were therefore corrected using a rotation matrix. During the survey, the heights of the source and the receiver and their offsets vary in real time and the measured data are contaminated with noise. The noise makes it difficult to interpret the data using the conventional method. Therefore, we developed a recurrent neural network (RNN) model to enable rapid predictions of the apparent resistivity using magnetic field data. Field data noise is included in the training datasets of the RNN model to improve its performance on noise-contaminated field data. Compared with the results of the electrical resistivity survey, the trained RNN model predicted similar apparent resistivities for the test field dataset.

• Journal of the Korea Computer Graphics Society
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• v.20 no.1
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• pp.1-11
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• 2014

Patients with cerebral palsy or arthritis have deformities in lower limb which cause unstable gait or posture and pains. Surgeons perform a deformity correction osteotomy with surgical plan. But sometimes they find the unexpected angular or rotational deformation after surgery. The problems are that there is no method to predict the result of a surgical plan and also there are so many factors to must consider in surgical planning step such as clinical measurements, rotation angle, wedge angle, morphology of lower limb, etc. This paper presents new methods for planning the deformity correction osteotomy efficiently. There are two approaches based on the 3D mesh model and the accurate assessment of the patient's lower limb. One is the manual pre-simulation of surgery using forward kinematics. And the other is the automatic surgical planning using inverse kinematics and nonlinear optimization. Using these methods, we can predict and verify the results of various surgical treatments and also we can find a more effective surgical plan easily compared to conventional methods.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.126-132
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• 1999

This article describes the use of an activator with anterior high pull headgear to treat a skeletal Class II malocclusion in children in the mixed-dentition phase. A combination of headgear-activator appliance can inhibit forward and downward growth of the maxillary complex while stimulating mandibular growth. The correction of Class II malocclusion can be achieved by careful case selection of a motivated patient with a favorable growth pattern. The patients who have skeletal Class II malocclusions were treated by means of activator with anterior high pull headgear and the following results were observed; 1. Forward and downward growth of the maxillary complex were inhibited 2. Mandibular growth was stimulated and counterclockwise rotation of the mandible was observed. 3. Large overjet and deep overbite were corrected.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.92.1-92.1
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• 2013

In this study, we examined chromospheric oscillation signatures in two solar active regions, a limb active region and a sunspot with a light bridge, observed by the Fast Imaging Solar Spectrograph (FISS) of the 1.6m New Solar Telescope (NST) at Big Bear Solar Observatory. The FISS is a slit spectrograph with a fast imaging capability and can observe the solar chromosphere in $H{\alpha}$ and Ca II $8542{\AA}$ bands simultaneously with high spectral resolutions. After dark and flat correction, we compensated for image rotation at the Coude focus and made image alignment. We estimated Doppler shifts over active regions using the bisector method and investigated the temporal and spatial fluctuations of Doppler shifts for some selected cases. And we obtain the power map by using the Lomb-Scargle periodogram technique to examine the oscillation power at different features. Finally, we will discuss our results and implications.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.187-194
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• 2006

Unexpected postoperative changes, such as growth in rib hump and shoulder unbalance, have been occasionally reported after corrective surgery for scoliosis. However there has been neither experimental data fer explanation of these changes, nor the suggestion of optimal correction method. Therefore, the numerical study was designed to investigate the post-operative changes of vertebral rotation and rib cage deformation after the corrective surgery of scoliosis. A mathematical finite element model of normal spine including rib cage, sternum, both clavicles, and pelvis was developed with anatomical details. In this study, we also developed a special program which could convert a normal spine model to a desired scoliotic spine model automatically. A personalized skeletal deformity of scoliosis model was reconstructed with X-ray images of a scoliosis patient from the normal spine structures and rib cage model. The geometric mapping was performed by translating and rotating the spinal column with an amount analyzed from the digitized 12 built-in coordinate axes in each vertebral image. By utilizing this program, problems generated in mapping procedure such as facet joint overlapping, vertebral body deformity could be automatically resolved.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.12
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• pp.1073-1080
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• 2015

A drive shaft is used to transmit torque and rotation through the connection of components of a drive train. Recently, a monobloc drive shaft without welding regions is developed to improve the safety of the drive shaft. The drive shaft bears the shear stress induced by torque. The objective of this paper is to investigate into the structural safety of a monobloc tubular drive shaft subjected to torque. Elasto-plastic finite element (FE) analysis is performed to estimate the deformation behavior of the drive shaft and stress-strain distribution in the drive shaft. Several techniques are used to create finite element (FE) model of the monobloc tubular drive shaft subjected to torque. Through the comparison of the results of FE analyses with those of experiments from the viewpoint of rotational angle, appropriate correction coefficients for different load conditions are estimated. The safety of the tubular drive shaft is examined using the results of FE analyses for different load conditions. Finally, it is noted that the designed tubular drive shaft has a sufficient structural safety.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.1
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• pp.28-38
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• 2010

The factors influencing the relapse and recurrence of skeletal deformity after the orthognathic surgery include various factors such as condylar deviation, the amount of mandibular set-back, stretching force by the soft tissues and muscles around the facial skeleton. The purpose of this report is to recognize and analyze the possible factors of reoperation after orthognathic surgery, due to early relapses. Six patients underwent reoperation after the orthognathic surgeries out of 110 patients from 2006 to 2009 were included in this study. In most cases, clincal signs of the insufficient occlusal stability, anterior open bite, and unilateral shifting of the mandible were founded within 2 weeks postoperatively. Although elastic traction was initiated in every case, inadequate correction made reoperation for these cases inevitable. The chief complaints of five cases were the protruded mandible combined with some degree of asymmetric face and in the other one case, it was asymmetric face only. Various factors were considered as a major cause of post-operative instability such as condylar sagging, counter-clockwise rotation of the mandibular segment, soft tissue tension related with asymmetrical mandibular set-back, preoperatively existing temporomandibular disorder (TMD), poor fabrication of the final wafer, and dual bite tendency of the patients.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.3-6
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• 2008

Electrolytic in-process dressing (ELID) grinding is a new technique for achieving a nanoscale surface finish on hard and brittle materials such as optical glass and ceramics. This process applies an electrochemical dressing on the metal-bonded diamond wheels to ensure constant protrusion of sharp cutting grits throughout the grinding cycle. In conventional ELID grinding, a constant source of pulsed DC power is supplied to the ELID cell, but a feedback mechanism is necessary to control the dressing power and obtain better performance. In this study, we propose a new closed-loop wheel dressing technique for grinding wheel truing that addresses the efficient correction of eccentric wheel rotation and the nonuniformity in the grinding wheel profile. The technique relies on an iterative control algorithm for the ELID power supply. An inductive sensor is used to measure the wheel profile based on the gap between the sensor head and wheel edge, and this is used as the feedback signal to control the pulse width of the power supply. We discuss the detailed mathematical design of the control algorithm and provide simulation results that were confirmed experimentally.

• New & Renewable Energy
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• v.9 no.1
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• pp.12-16
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• 2013

The nacelle anemometer mounted behind the blade roots of a wind turbine measures distorted wind speed comparable with free-stream wind because of the wake effects caused dependent upon the operation of the wind turbine and the rotation of its blades. The field campaign was carried out to measure free-stream wind speed at a height identical to the height of the nacelle anemometer by deploying a ground-based remote-sensing equipment, LIDAR. It is derived that a third-order polynomial equation for correcting wind speed measured by the nacelle anemometer to undistorted free-stream wind speed incident to a wind turbine. It is anticipated that the derived correction equation enables wind speed measured by the nacelle anemometer to be used as a precise input for a wind turbine performance test and for developing an active control logic.