• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1546-1549
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• 2007

A ride quality measurement was carried out for commuter and express train used in airport railway. Lateral and vertical directional average ride quality level is higher than that of longitudinal direction. Because express train is faster than commuter train, the average ride quality level of express train is higher compared to that of commuter train. The average ride quality level of commuter train is between 'good comfortable($100{\sim}105dB$)' and 'very good comfortable(below 100dB)'. The average ride quality level of express train is between 'not comfortable($105{\sim}110dB$)' and 'good comfortable($100{\sim}105dB$)'. In spite of the scheduled speed is higher(more than 70km/h for commuter train, more than 80km/h for express train) than other lines, the ride quality of airport railway train is good. The reason is that there is little gradient in rail and the radius of curvature is larger compared to that of other lines.

• The korean journal of orthodontics
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• v.50 no.4
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• pp.249-257
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• 2020

Objective: To evaluate the changes in the nose in three dimensions after Le Fort I osteotomy in patients with skeletal Class III malocclusion. Methods: The subjects were 40 adult patients (20 females and 20 males; mean age, 20.3 ± 3.0 years; range, 17.0 to 31.1 years) who underwent one-piece Le Fort I osteotomy with maxillary advancement and impaction treatment for maxillary hypoplasia. The mean maxillary advancement was 4.56 ± 1.34 mm, and the mean maxillary impaction was 2.03 ± 1.04 mm. Stereophotogrammetry was used to acquire three-dimensional images before and at least 6 months after surgery. Results: Alare (Al) and alare curvature (Ac) points had moved vertically and anterolaterally postoperatively. A significant increase was observed in the nasal ala width and alar base width, and no changes were noted in the columellar length, nasolabial angle, and nasal area. There was a significant relationship between maxillary impaction and nasal ala width and horizontal and sagittal positions of the bilateral Al and Ac. The only relationship found was between maxillary advancement and postoperative sagittal location of the subnasale and pronasale. Conclusions: Nasal soft tissues were highly affected by the vertical movement of the maxilla; however, the soft tissue responses were individual-dependent.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.4
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• pp.403-413
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• 1985

Hot-wire measurements of second and third-order mean products of velocity fluctuations have been made in the separated, reattached, and redeveloping boundary layer behind a vertical fence. Mean velocity, wall static pressure distributions have also been measured in the whole flow field. Upstream of the reattachment point, the separated shear layer developes as a free mixing layer, but the gradient of the maximum slope thickness, turbulent intensities and the Reynolds shear stress are higher than that of the mixing layer due to initial streamline curvature and the effects of highly turbulent recirculating flow region. In the reattachment region, Reynolds shear stress and triple products near the surface is far more rapid than the decrease of the shear stress; that is the presence of the solid wall has a marked effect on the apparent gradient diffusivity of intensity or shear stress and throws doubts upon the usefulness of the simple gradient diffusivity model in this region.

• Tribology and Lubricants
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• v.26 no.3
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• pp.184-189
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• 2010

In this paper, tactile response characteristics in medical haptic interface are investigated to characterize the feeling of contact between the finger skin and the organic tissue when a finger is dragged over tissue. In order to represent the tactile feeling, a prototype tactile display incorporating Magneto-Rheological (MR) fluid has been developed. Tactile display devices simulate the finger's skin to feel the sensations of contact such as compliance, curvature and friction. Thus, the tactile display provides the surface information of organic tissue to the surgeon using different actuating mechanisms ranging from the conventional mechanical motor to the smart material actuators. In order to investigate the compliance feeling of human finger's touch, vertical force responses of the tactile display under the various magnetic fields have been assessed. Also, frictional resistive force responses of the tactile display are investigated to simulate the action of finger's dragging. From the results, different tactile feelings are observed as the applied magnetic field is varied and arrayed magnetic poles combinations. This research gives a smart technology of tactile displaying.

• Transactions of Materials Processing
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• v.17 no.1
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• pp.27-34
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• 2008

In order to manufacture a doubly curved sheet metal, the incremental roll forming process which adopts advantages such as the flexibility of the incremental forming process and continuous bending deformation of the roll forming process has been experimentally investigated. An experimental equipment was developed which was named as unit roll set (URS) consisting of two pairs of support rolls and an upper center roll. The upper roll equipped with the servo control unit is motor-driven and can be positioned in the vertical direction according to the user's commands. Four support rolls are idle, and they freely rotate only along the axis so as to transfer the plate more stably in the tangential direction of the rotation of the driving roll. In the process, the plate is deformed incrementally as deformation proceeds simultaneously in longitudinal and transverse directions. Through the experiments using URS, information regarding to forming schedules is found out to fabricate curved hull plates. This study demonstrates the further application of the incremental roll forming process in shipbuilding industries.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.432-432
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• 2011

Dry adhesion caused by Nanoscale contact comes up to important scientific issue. Herein, we introduce bendable nanohairy locking fastener system with high shear strength and mechanically flexible backing. The polymeric patches like velcro are composed of an array of straight nanohairs with 100 nm diameter and $1{\mu}m$ height. To fabricate high aspect vertical nanohairs, we used UV molding method with appropriately flexible and rigid polyurethane acrylate material on PET substrate. Two identical nanohairy patches are easily merged and locked each other induced by van der Waals force. Because nanohairs can be arrayed with high density ${\sim}4{\times}10^8/cm^2$, we can obtain high shear adhesion force on flat surface (~22 N/$cm^2$). Furthermore, we can obtian nanohairy locking system with maximum shear adhesion ~48 N/$cm^2$ of curved surface due to flexibility of PET substrate. We confirm the tendency that shear adhesion force increases, as radius of curvature increases.

• Earthquakes and Structures
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• v.9 no.6
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• pp.1233-1250
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• 2015

The behavior of reinforced concrete (RC) columns made from high strength materials was investigated experimentally. Six high-strength concrete specimen columns (1:4 scale), which included three with high-strength transverse reinforcing bars and three with normal-strength transverse reinforcement, were tested under double curvature bending load. The effects of yielding strength and ratio of transverse reinforcement on the cracking patterns, hysteretic response, shear strength, ductility, strength reduction, energy dissipation and strain of reinforcement were studied. The test results indicated that all specimens failed in splitting failure, and specimens with high-strength transverse reinforcement exhibited better seismic performance than those with normal-strength transverse reinforcement. It also demonstrated that the strength of high-strength lateral reinforcing bars was fully utilized at the ultimate displacements. Shear strength formula of short concrete columns, which experienced a splitting failure, was proposed based on the Chinese concrete code. To enhance the applicability of the model, it was corroborated with 47 short concrete columns selected from the literature available. The results indicated that, the proposed method can give better predictions of shear strength for short columns that experienced a splitting failure than other shear strength models of ACI 318 and Chinese concrete codes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.95-104
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• 2004

The horizontally curved bridges have been used to connect bridges and roads. Until 1960s, they had been constructed with straight girders, called 'kinked girder bridges', which requires much cost and time-consuming construction of substructure. In case of using curved girders, practiced later, they would have many advantages such as reduction in the total construction cost and time, and ability to make aesthetic bridges. In designing plate girder bridges, it is necessary to determine the spacings between vertical stiffeners and the allowable shear stresses based on shear buckling capacity because it plays a key role in preventing the premature local shear buckling. Compared with the straight web, the critical shear buckling stresses of curved web panels vary with both aspect ratio and curvature coefficient. For designing curved web panels, a simplified formula and shear buckling coefficients were proposed by parametric models with F.E.M in this study.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.5
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• pp.517-525
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• 2007

This paper presents how to approximate an optimal shape of roll bending process in the fabrication of a curved shell plate. The roll bending process usually makes the cylindrical or conic shape from an initial flat plate. It means that the final shape is developable or its surface representation has zero Gaussian curvature. The fabrication shape is important in order to find process parameters of roil bending. An optimal concept is used to determine the developable fabrication shape which is in the closest proximity to the design surface or the given shell plate and is subject to developability. The results and the efficiency of this algorithm are evaluated by applying to some shell plates. Furthermore, the fabrication shape will be fundamental information for other process parameters of roll bending such as the vertical displacement of the center roller and the rolling directions.

• Journal of Oral Medicine and Pain
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• v.43 no.3
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• pp.77-83
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• 2018

Purpose: The present study was designed to investigate the association of ponticulus posticus (PP) and elongated styloid process (ESP) with headaches. Methods: Analysis of head and neck cone beam computed tomography samples from the archives of the Department of Oral Radiology was done for the presence of partial or complete PP and ESP length, type, thickness, mediolateral angulation, anterioposterior angulation (horizontal & vertical), lateral or medial curvature. This was followed by personal & telephonic questionnaires to the subjects for the evaluation of the presence of headaches & other associated symptoms. Results: Among 134 subjects, 62 subjects (46.3%) presented with headache and 72 subjects (53.7%) did not have any headache. On further analysing the total 62 subjects with headache, it was found out that 31 subjects (50.0%) of them had ESP and PP both, 16 subjects (25.8%) had only ESP, and 15 subjects (24.2%) had only PP. A strong association was present between headache and presence of PP & ESP individually and together. Conclusions: All health care professionals dealing with the head and neck pain disorders should also consider the presence of ESP & PP during diagnosis and treatment.