• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.275-282
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• 2018

Mountain trams are an environmental-friendly transportation system that run wirelessly on an embedded track constructed on previous mountain roads, and can run despite the frozen road. On the other hand, there is some difficulty on sharp and steep tracks. In this study, after possible technical problems were defined in mountain trams running on a sharp and steep track, the design solutions for the interface structure of bogie and carbody were proposed. In addition, a prototype was made and its performance was tested to verify the solutions. Because the difference in the distance of the inner and outer rails on a sharp curve is severe enough to interrupt running, independent rotating wheels with different angular speeds were developed and applied. To prevent derailment due to the large attack angle and lateral force caused by the previous vehicle of 2bogie-and-1carbody on the sharp curve, a vehicle with 1bogie-and-1carbody was designed and applied. A prototype vehicle of 1bogie-and-1carbody with independent rotating wheels was made to improve the performance during the test running on a small track. A coupler was designed to absorb the large rotations of 3 degrees-of-freedom between the carbodies of a mountain tram running on the steep curved track. After a small scale prototype was made, the performance was verified by a function test.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.3
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• pp.341-351
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• 2003

Digital image watermarking is the method that can protect the copyright of the image by embedding copyright information, which is called watermark. Watermarking must have robustness to intentional or unintentional data changing, called attack. The conventional watermarking schemes are robust to waveform attacks such as image compression, filtering etc. However, they are vulnerable to geometrical attacks such as rotation, scaling, translation, and cropping. Accordingly, this paper proposes new watermarking scheme that is robust to geometrical attacks by using invariant centroid. Invariant centroid is the gravity center of a central area in a gray scale image that remains unchanged even when the image is attacked by RST including cropping and proposed scheme uses invariant centroids of original and inverted image as the template. To make geometrically invariant domain, template and angle compensated Log -Polar Map(LPM) is used. Then Discrete Cosine Transform(DCT) is performed and the watermark is embedded into the DCT coefficients. Futhermore, to prevent a watermarked image from degrading due to interpolation during coordinate system conversion, only the image of the watermark signal is extracted and added to the original image. Experimental results show that the proposed scheme is especially robust to RST attacks including cropping.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.809-818
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• 2019

Since January 1, 2020, the International Maritime Organization (IMO) has put in place strong regulations to reduce air pollution caused by ships by lowing the upper limit of ship fuel oil sulfur content from 3.5% to 0.5% for ships passing through all sea areas around the world. Although it is important to reduce air pollutants by using fuel oil with low sulfur content, reducing the amount of energy waste through the economic operation of a ship can also help reduce air pollutants. Ships can follow designated routes accurately even under the influence of noise using autopilot systems. However, regardless of their quality, the performance of these systems is af ected by noise; heading angles with added measurement noise from the gyroscope are input into the autopilot system and degrade its performance. A technique to solve these problems reduces noise effects through the application of a Kalman filter, which is widely used in condition estimation. This method, however, cannot completely eliminate the effects of noise. Therefore, to further improve noise removal performances, in this study we propose a better denoising method than the Kalman filter technique by applying a multi-layer perceptron (MLP) in forward direction motion and a Kalman Filter in rotation motion. Simulations show that the proposed method improves forward direction motion by preventing the malfunction of a rudder more so than merely using a Kalman Filter.

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.557-566
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• 1995

Postpubertal craniofacial growth changes were assessed from serial lateral cephalograms taken at which subjects were 16 and 18 years of age. The sample consisted of 19 male and 14 female subjects with no previous orthodontic treatment who had normal occlusion. The craniofacial growth changes of these samples during this study period might be summarized as follows 1. Significant increase in mean maxillary and mandibular length, cranial base length, posterior md anterior facial height were observed at the age period studied in male(P<0.05), however, in female significant increase was observed only mandibular length(Ar-Gn, Ar-Go) and anterior and posterior facial height(P<0.05). 2. Total growth increment of all measumenats were below 1mm in female, but in male, total mandibular(Ar-Gn) growth increment was 2.0mm and those of mandibular tody length, ram length, posterior facial height, and anteior facial height were 1 to 1.54mm and the others were below 1mm 3. A closing, forward rotation of the mandible occured with a significant decrease in mandibular plane angle of $0.61^{\circ}$ in male(P<0.01). 4. Summarized the findings, even though statistically significant growth changes in some dimensions of female were observed, the amount of growth change were very small, however, in male the growth changes of some dimensions associated with mandible were significant and considerable amount.

• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.361-376
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• 1995

The purpose of this study was to investigate the relationship between the head and neck postre and the cervical curvature, especially in forward head postrue(FHP). Sixty patients with craniomandibular disorders and thirty dental students without any signs and symptoms of craniomandibular disordres participated in this study as patient groups and sa control group, respectively. The author evaluated the head and neck posture of all subjects by plumb line and CROM( Cervical Ragne of Motion), and had taken cephaograph in natural head position. On the cephalograph the angle of cervical inclination formed by true horizntal plane and 4th cervical vertebra(C4) and the radius of cervical curvature from C1 to C5 were measured. A specially designed ruler was used for measuring cervical curvature. Occlusal contac number and force with T-scan system, electromygraphic activity of cervical muscles with Bio-EMG, and distance of freeway space with Bio-ECN were recorded, respectively. The collected data were processed by SAS/STAT progrm. The obtained results were as follows : 1. In subjects with longer radius which was less cervical curvature, head positioned more anteriorly than subjects with smaller radius, and they showed slightly straight cervical vertebra. 2. Between the patients and the control group, there were no differences in cervical curvature, in forward head position by plumb line and in CROM. But the patient group had a greater cervical inclination than the control group had. 3. There were positive correlation between cervical curvature and forward head position by plumbline,between forward head position y plumb line and that by CROM in patient group. The cervical inclination, however, had negative correlation with cervical curvature, and with forward head postion by plumb line, respectively. 4. In case of showing more cervical curvature and more forward head position by plumb line the head position was defined as forward head posture. In patient group, subjects without forward head posture showed greater posterior teeth contact force than subjects with forward head posture, but in control group, there were no difference between the two subjects. 5. There were higher electromyographic activity in almost all muscles and smaller freeway space in induced forward head posture than those in natural head position in subjects without forward head posture. In conclusion, head position of patients with craniomandibular disorders were not more anterior than that of normal control person, but they had tendency to head extension. From the result of this study, forward head posture could be defined as posterior rotation of upper cervical segment with a straight lower cercial segment due to loss of normal lordosis.

• Progress in Medical Physics
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• v.18 no.1
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• pp.35-41
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• 2007

In this work practical considerations of a pulsed arterial spin labeling MRI are presented to reliable multi-slice perfusion measurements In the human brain. Three parameters were considered in this study. First, In order to improve slice profile and Inversion efficiency of a labeling pulse a high power Inversion pulse of adiabatic hyperbolic secant was designed. A $900^{\circ}$ rotation of the flip angle was provided to make a good slice profile and excellent Inversion efficiency. Second, to minimize contributions of a residual magnetization be4ween Interleaved scans of control and labeling we tested three different conditions which were applied 1) only saturation pulses, 2) only spotter gradients, and 3) combinations of saturation pulses and spotter gradients Applications of bo4h saturation pulses and spoiler gradients minimized the residual magnetization. Finally, to find a minimum gap between a tagged plane and an imaging plane we tested signal changes of the subtracted image between control and labeled Images with varying the gap. The optimum gap was about 20mm. In conclusion, In order to obtain high quality of perfusion Images In human brain It Is Important to use optimum parameters. Before routinely using In clinical studios, we recommend to make optimizations of sequence parameters.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.337-347
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• 2011

In this study, seismic resistance of concrete encased U-shaped steel beam-to-steel H-shaped column connections was evaluated. Three specimens of the beam-to-column connection were tested under cyclic loading. The composite beam was integrated with concrete slab using studs. Re-bars for negative moment were placed in the slab. The primary test parameter was the details of the connections, which are strengthening and weakening strategies for the beam end and the degree of composite action. The depth of the composite beams was 600mm including the slab thickness. The steel beam and the re-bars in the slab were weld-connected to the steel column. For the strengthening strategy, cover plates were weld-connected to the bottom and top flanges of the steel beam. For the weakening strategy, a void using styrofoam box was located inside the core concrete at the potential plastic hinge zone. The test results showed that the fully composite specimens exhibited good strength, deformation, and energy dissipation capacities. The deformation capacity of the beam exceeded 4% rotation angle, which is the requirement for the Special Moment Frame.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.325-334
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• 2010

In this study, an unbraced five-story steel-framed structure was designed in accordance with KBC2005 to understand the features of structural behavior for the arrangement of semi-rigid connections. A pushover analysis of the structural models was performed, wherein all the connections were idealized as fully rigid and semi-rigid. Additionally, horizontal and vertical arrangements of the semi-rigid connection were adopted for the models. A fiber model was utilized for the moment-curvature relationship of the steel beam and the column, and a three-parameter power model was adopted for the moment-rotation angle of the semi-rigid connection. The top displacement, base-shear force, required ductility for the connection, sequence of the plastic hinge, and design factors such as the overstrength factor, ductility factor, and response modification coefficient were investigated using the pushover analysis of a 2D structure subjected to the equivalent static lateral force of KBC2005. The partial arrangement of the semi-rigid connection was found to have secured higher strength and lateral stiffness than that of the A-Semi frame, and greater ductility than the A-Rigid frame. The TSD connection was found suitable for use for economy and safety in the sample structure.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.313-324
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• 2010

In this study, an unbraced five-story steel-framed structure was designed in accordance with KBC2005 to understand the features of structural behavior for the arrangement of semi-rigid connections. An inelastic time history analysis of structural models was performed, wherein all the connections were idealized as fully rigid and semi-rigid. Additionally, horizontal and vertical arrangements of semi-rigid connections were used for the models. A fiber model was utilized for the moment-curvature relationship of a steel beam and a column, a three-parameter power model for the moment-rotation angle of the semi-rigid connection, and a three-parameter model for the hysteretic behavior of a steel beam, column, and connection. The base-shear force, top displacement, story drift, required ductility for the connection, maximum bending moment of the column, beam, and connection, and distribution of the plastic hinge were investigated using four earthquake excitations with peak ground acceleration for a mean return period of 2,400 years and for the maximum base-shear force in the pushover analysis of a 5% story drift. The maximum base-shear force and story drift decreased with the outer vertical distribution of the semi-rigid connection, and the required ductility for the connection decreased with the higher horizontal distribution of the semi-rigid connection. The location of the maximum story drift differed in the pushover analysis and the time history analysis, and the magnitude was overestimated in the pushover analysis. The outer vertical distribution of the semi-rigid connection was recommended for the base-shear force, story drift, and required ductility for the connection.

• Journal of Korean Society of Steel Construction
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• v.22 no.2
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• pp.129-137
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• 2010

In this study, a five-story steel frame was designed in accordance with KBC2005 to evaluate the effect of the beam-column connection on the structural behavior. The connections were designed as a fully rigid connection and as a semirigid connection. A fiber model was utilized to describe the moment-curvature relationship of the steel beam and column, and a three-parameter power model was adopted for the moment-rotation angle of the semirigid connection. To evaluate the effects of higher modes on structural behavior, the structure was subjected to a KBC2005-equivalent lateral load and lateral loads considering higher modes. The structure was idealized as a separate 2D frame and as a connected 2D frame. The pushover analysis of 2D frames for the lateral load yielded the top displacement-base shear force, design coefficients such as overstrength factor, ductility ratio, and response modification coefficient, demanded ductility ratio for the semirigid connection,and distribution of plastic hinges. The sample structure showed a greater response modification coefficient than KBC2005, the higher modes were found to have few effects on the coefficient, and the lateral load of KBC2005 was found to be conservative. The TSD connection was estimated to secure economy and safety in the sample structure.