• Journal of Korean Neurosurgical Society
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• 제59권6호
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• pp.610-614
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• 2016

Objective : The purpose of this study was to present the outcome of the microsurgical foraminotomy via Wiltse paraspinal approach for foraminal or extraforaminal (FEF) stenosis at L5-S1 level. We investigated risk factors associated with poor outcome of microsurgical foraminotomy at L5-S1 level. Methods : We analyzed 21 patients who underwent the microsurgical foraminotomy for FEF stenosis at L5-S1 level. To investigate risk factors associated with poor outcome, patients were classified into two groups (success and failure in foraminotomy). Clinical outcomes were assessed by the visual analogue scale (VAS) scores of back and leg pain and Oswestry disability index (ODI). Radiographic parameters including existence of spondylolisthesis, existence and degree of coronal wedging, disc height, foramen height, segmental lordotic angle (SLA) on neutral and dynamic view, segmental range of motion, and global lumbar lordotic angle were investigated. Results : Postoperative VAS score and ODI improved after foraminotomy. However, there were 7 patients (33%) who had persistent or recurrent leg pain. SLA on neutral and extension radiographic films were significantly associated with the failure in foraminotomy (p<0.05). Receiver-operating characteristics curve analysis revealed the optimal cut-off values of SLA on neutral and extension radiographic films for predicting failure in foraminotomy were $17.3^{\circ}$ and $24^{\circ}s$, respectively. Conclusion : Microsurgical foraminotomy for FEF stenosis at L5-S1 level can provide good clinical outcomes in selected patients. Poor outcomes were associated with large SLA on preoperative neutral (>$17.3^{\circ}$) and extension radiographic films (>$24^{\circ}$).

• Journal of the Korean Society for Advanced Composite Structures
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• 제1권3호
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• pp.24-34
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• 2010

This paper analyzed the partial differential equations of laminated composite shells of revolution by using the finite difference method. The proof that numerical results are reasonable and accurate is obtained through converge ratio analysis and commercial program LUSAS for the structural analysis. The purpose of this study is to examine closely the engineering advantages and to analyze the structural behaviors of the anisotropic shells of revolution. Thus, the relevant reinforcement and most suitable arrangement of fiber to produce the highest strength are proposed through the numerical results according to a variety of parameter study. Namely, the distribution of displacements and stress resultants are analyzed according to the change of meridian's curvature, the ratio of height-width of shell, subtended angle, fiber angle, and so on. Using these distribution, the most suitable shell may be proposed to produce the highest strength. Also, the configuration of the entire laminated composite conical shells is analysed, and a variety of the design criterion of circular conical shell are proposed and studied in engineering view points.

• Korean Journal of Applied Biomechanics
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• 제16권4호
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• pp.195-203
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• 2006

The isometric rehabilitation program was applied to 47 people of the aged low back patients(man 22 people, woman 25 people) twice a week for 8weeks. The Medx was used to study an effect on a change for extended strength ratio(ESR) according to a posture change. The isometric ESR at each flexion angle ($0^{\circ}$, $12^{\circ}$, $24^{\circ}$, $36^{\circ}$, $48^{\circ}$, $60^{\circ}$, $72^{\circ})$ was measured total 3times("before excercise", "on 4th week after excercise", "8th week after excercise") and analyzed. So, we could come to a conclusion as follows. 1. The maximum extended strength measured at a range of 7 angles for an isometric excercise of 8 weeks increased than "before an excercise", including that men have an increase of 39.51% and women have 62.92% in training effect. All of men and women showed statistically significant increase in physical strength(p<.001).excercise") and analyzed. So, we could come to a conclusion as follows. 2. After an excercise of 8 weeks, man showed 62.17% at zero degree and 49.115% at 12 degree respectively in maximum extended strength. Women showed 106.6% at zero degree and 86.16% at 12 degree. In view of this, respectively man have increase rate of physical strength over 31% and women have over 46% at all angles, also have significant increase in extension angle(p<.001). 3. A change for isometric ESR have a decrease of 27.68% for men and 74.66% for women than before isometric excercise of 8 weeks statistically significantly(p<.05, p<.00l). Men showed 1.77:1 of a similar ratio in the decrease effect comparing with normal people, but women showed 225:1.

• Journal of the Korean Chemical Society
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• 제7권4호
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• pp.230-237
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• 1963

The synthesis of 2-methyl-5,5'-gem-disubstituted-$\Delta^2$-thiazolines has been undertaken by two methods. The first involves the preparation of gem-disubstituted N-or S-acetylamino mercaptan intermediates by ring opening of the corresponding thiiranes with ammonia. The second consists of the ring opening of gem-disubstituted ethylene imines using thiolacetic acid. The thiirane rings have never been opened under conditions as vigorous as that of using sodium amide in liquid ammonia. This is probably due to retardation by the gem-disubstituents. In contrast to this, the corresponding ethylene imine ring opens easily, in spite of the same stereochemical situation. The stabilization of gem-disubstituted cyclic compounds has been discussed from a stereochemical point of view. It has been concluded from the results of this work that the compression effect of gem-disubstitution is not due to bond angle deformation, which was observed by Thorpe and Ingold, but mostly to an electronic bond interaction of the gem-disubstituents and to the hetero atom(s), if any.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• 제18권2호
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• pp.63-72
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• 2018

Theoretical modelling and computational results for frequency coordination are presented based upon minimum coupling loss regarding the same or different wireless systems. Essential parameters involved in frequency coordination are discussed in view of system characteristics, propagation model, availability and protection ratio, frequency dependent rejection or adjacent channel interference ratio, discrimination angle, and its computational results are also evaluated. To illustrate frequency coordination procedure, received interference power between fixed wireless system of victim and mobile base station of interferer are analyzed in urban or sub-urban area and also compared with maximum allowable interference power as functions of discrimination angle and distance for assumed system parameters. The proposed method will play a practical role in technical analysis on co-existence or interoperability for the various wireless systems needed for frequency coordination.

• Journal of Institute of Control, Robotics and Systems
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• 제20권1호
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• pp.70-77
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• 2014

This paper proposes a novel localization algorithm based on ego-motion which used Lucas-Kanade Optical Flow and warping image obtained through fish-eye lenses mounted on the robots. The omnidirectional image sensor is a desirable sensor for real-time view-based recognition of a robot because the all information around the robot can be obtained simultaneously. The preprocessing (distortion correction, image merge, etc.) of the omnidirectional image which obtained by camera using reflect in mirror or by connection of multiple camera images is essential because it is difficult to obtain information from the original image. The core of the proposed algorithm may be summarized as follows: First, we capture instantaneous $360^{\circ}$ panoramic images around a robot through fish-eye lenses which are mounted in the bottom direction. Second, we extract motion vectors using Lucas-Kanade Optical Flow in preprocessed image. Third, we estimate the robot position and angle using ego-motion method which used direction of vector and vanishing point obtained by RANSAC. We confirmed the reliability of localization algorithm using ego-motion based on fisheye warping image through comparison between results (position and angle) of the experiment obtained using the proposed algorithm and results of the experiment measured from Global Vision Localization System.

• Korean Journal of Optics and Photonics
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• 제17권1호
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• pp.38-46
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• 2006

The stereoscopic camera based on the image formation principle on human eyes and the brain is designed and fabricated by using a CCD and two zoom lenses. As two zoom lenses are separated as 65 mm of the human ocular distance with the wide angle of view of $50^{\circ}$ and the variable convergence angle from $0^{\circ}$ to $16^{\circ}$, the camera can be operated by the similar binocular parallax as human eyes. In order to take the dynamic stereoscopic picture, a shutter blade for the selection of the left and right images in turns, an X-cube image combiner fur the composition of these two images through the blade, and a CCD with 60 frames per second are used.

• Archives of Plastic Surgery
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• 제44권5호
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• pp.400-406
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• 2017

Background The purpose of this study was to evaluate changes in nasal growth after the implementation of a preoperative nasal retainer in patients with bilateral incomplete cleft lip. Methods Twenty-six infants with bilateral incomplete cleft lip and cleft palate were included in the study. A preoperative nasal retainer was applied in 5 patients from the time of birth to 2.6-3.5 months before primary cheiloplasty. Twenty-one patients who were treated without a preoperative nasal retainer were placed in the control group. Standard frontal, basal, and lateral view photographs were taken 3 weeks before cheiloplasty, immediately after cheiloplasty, and at the 1- and 3-year postoperative follow-up visits. The columella and nasal growth ratio and nasolabial angle were indirectly measured using photographic anthropometry. Results The ratio of columella length to nasal tip protrusion significantly increased after the implementation of a preoperative nasal retainer compared to the control group for up to 3 years postoperatively (P<0.01 for all time points). The ratios of nasal width to facial width, nasal width to intercanthal distance, columellar width to nasal width, and the nasolabial angle, for the two groups were not significantly different at any time point. Conclusions Implementation of a preoperative nasal retainer provided significant advantages for achieving columellar elongation for up to 3 years postoperatively. It is a simple, reasonable option for correcting nostril shape, preventing deformities, and guiding development of facial structures.

• Korean Journal of Applied Biomechanics
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• 제21권5호
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• pp.631-638
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• 2011

This study had two purposes. The first was to analyze the period of the final record set by the male shot-putters in the IAAF World Championships, Daegu 2011 from the point of view of kinematics. The other was to identify an efficient movement for shot putting based on the analysis. The research used the eight finalists of in the championship as subjects. We analyzed the seven most important kinematic factors in shot putting based on the type of technique: the execution time of the delivery phase, release velocity, release angle, release, center of mass (COM) velocity, and shot trajectories. The analytical results showed the following average figures for the record 12 meters: execution time of the delivery phase: (0.19 s), release height: (2.06 m), release angle: ($34.68^{\circ}$), release velocity: (13.25 m/s), angular velocity of shoulder: ($922.38^{\circ}/s$), and angular velocity of pelvis: ($479.50^{\circ}/s$). Further, the results showed that the highest COM velocity was 2.25 m/s and the shot trajectories were close to a straight line in the release phase.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제47권1호
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• pp.37-45
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• 2011

Reduction of ship's rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargo as well as improving the comfort of the ride. It is a common experience for mariners, to see that steering with a rudder generally induces rolling of the ship, though the original aim of the rudder is to keep the ship's heading to the required course. At the first stage, when a rudder is steered, usually a ship heels in an inward direction, due to the roll moment acting on the rudder. At the next stage in steering, the main heel may change to an outward. This coupling between rudder and roll motion has become an attractive problem from the point of view of roll stabilization using the rudder, because it is a natural in sight that if the rudder action is skillfully related to the change of roll as well as to the course deviation, the roll can be reduced to a certain degree. The main aim of this paper is to discuss the results of the actual full-scale sea trials carried out on steer gear No.1 and No.1 2, the individual quartermaster and to make clear their statistical properties, using the actual data which included measurement of roll angle, roll rate and the comparative tests were carried out immediately after each other, in order to minimize any statistical variation in sea conditions. It can be concluded that the steer gear No. 1 2 reduced the roll motion on average by about 21% in comparison with the No.1 and confirmed the some difference as per a ability of quarter-master's maneuver.