• Honam Mathematical Journal
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• v.43 no.3
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• pp.453-463
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• 2021

In this study, tubular surfaces that play an important role in technological designs in various branches are examined for the case of the base curve is not satisfying the fundamental theorem of the differential geometry. In order to give an alternative perspective to the researches on tubular surfaces, the modified orthogonal frame is used in this study. Firstly, the relationships between the Serret-Frenet frame and the modified orthogonal frame are summarized. Then the definitions of the tubular surfaces, some theorems, and results are given. Moreover, the fundamental forms, the mean curvature, and the Gaussian curvature of the tubular surface are calculated according to the modified orthogonal frame. Finally, the properties of parameter curves of the tubular surface with modified orthogonal frame are expressed and the tubular surface is drawn according to the Frenet frame and the modified orthogonal frame.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.201-204
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• 2006

A three-dimensional finite element (FEM) model has been developed to simulate the deformation due to bead on plate welding of curved plates with curvature in the weld direction. By using traditional method such as thermal-elastic-plastic FEM, the weld-induced deformation can be predicted accurately. However, this method is not practical approach to analyze the deformation of large and complex structures such as ship hull structures in view of time and cost. This study is classified from the aspect of equivalent load based on inherent strain near the weld line. Therefore, the residual deformation can be simply computed by elastic analysis. Further more, a practical solution is proposed to consider the contact between the plate and the positioning jig by judging the reaction forces of the jig at calculation step and the effect of the longitudinal curvature is closely considered.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.104-109
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• 2011

I present a method of aspheric surface profile measurement using 2nd derivative of local area profile. This method is based on the principle of curvature sensor which measures the local 2nd derivative under test along a line. The profile is then reconstructed from the data on the each point. Unlike subaperture-stiching method and slope detection method, 2nd derivative method has strong points from a geometric point of view in measuring the aspheric surface profile. The second derivative terms of surface profile is an intrinsic property of the test piece, which is independent of its position and tip-tilt motion. The curvature is measured at every local area with high accuracy and high lateral resolution by using White-light scanning interferometry.

• Archives of Plastic Surgery
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• v.50 no.2
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• pp.142-147
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• 2023

Some of Asian eyelids have double fold and some do not. Many people tend to prefer double eyelid in aesthetic and functional reasons. Since the mechanism of double eyelid is bonding the eyelid skin to the eye-opening tissue, the principle of double eyelid surgery is also connecting the eyelid skin to levator component. Double eyelids are differentiated by their shape according to the height and curvature. The double eyelid surgery procedure is divided into incision method and nonincision method. And the incision method is subdivided into double fold line design, skin and oculi muscle incision or excision, pretarsal or preaponeurotic soft tissue excision, fixation of posterior lamella to anterior lamella, and skin suture. The nonincision method is to connect the posterior lamella and the anterior lamella as a thread only without an incision. A successful double eyelid surgery creates a fold well-balanced in height, curvature, and depth of the fold based on patient's preference. In this article, the author's own methods of performing surgery are described, with a step-by-step guide and surgical tips.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.120-126
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• 2010

The line array roll set(LARS) process, as one of many kinds of incremental forming processes, is a continuous process in which a flat metal plate is formed into a singly or doubly curved plate through successive passes of forming rolls. It was found that the curvature level of the formed plates in the previous study was well over the curvature required in shipyards. This fact shows that the LARS method has good potential for shipbuilding applications. The major purpose of the present study is to estimate experimentally the general applicability of the line array roll set process for the manufacture of ship hull plates. In this study, the target shapes are selected through investigation of the shape classification of ship hull plates that comprise a certain vessel. Forming processes for twisted shapes are analyzed with the finite element method(FEM) and the results of experimental work are presented. On the basis of the experimental and numerical results, the LARS process is applied to the production of real outer hull plates of a small patrol ship.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.74-80
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• 2010

The purpose of reverse engineering design using 3D measurement data is an accurate reconstruction of real body. In oder to accomplish this object, it is important that creating exact extracting edges should be studying out first of all. This study used edge-based method to find out edge point from the measuring point data. The characteristics are analysed using the mean curvature block method on the fitting NURBS curve and defined edges through block removal condition. The results showed that only using the NURBS curve of maximum curvature analysis to define correct edge of real geometry is limited, but this segmentation approach provides simplified necessary condition for edge classification, and an effectiveness to classify a straight line, curves and fillets etc.

• Honam Mathematical Journal
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• v.46 no.1
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• pp.12-37
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• 2024

The paper introduces a set of new ruled surfaces such that the base curve is taken to be the striction curve of N, C and W ruled surfaces from the alternative frame, and the generating line is taken to be one of the vectors of Sannia frame. The characterizations for each ruled surface such as fundamental forms, the Gaussian and mean curvature are also examined to provide the conditions for each surface to be developable or minimal.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.289-292
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• 2009

The line array roll set process, as one of many kinds of incremental forming processes, is a continuous process in which a flat metal plate is formed into a singly or doubly curved plate through successive passes of forming rolls. It was found that the curvature level of the formed plates in the previous study was well over the curvature required in shipyards. This fact shows that the LARS method has considerable potential for shipbuilding applications. In a shipbuilding yard, hull forming is an important fabrication process in which flat plates are deformed into singly or doubly curved plates. The major purpose of the present study is to estimate experimentally the general applicability of the line array roll set process for the manufacture of ship hull plates. In this study, the target shapes are selected through investigation of the shape classification of ship hull plates that comprise a certain vessel. Forming processes for twisted shapes are analyzed with the finite element method (FEM). Finally, the results of experimental work for two types of target shapes are presented.

• Proceedings of KOSOMES biannual meeting
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• 2005.11a
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• pp.65-69
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• 2005

The theoretical propagation modes of radio waves in the area of Line of Sight(LOS) within Fresnel zone are searched for the available detection ranges in a Marine RFID (Radio Frequency Identification). The structural LOS model to Earth's curvature is proposed and, the calculation method of horizontal distance in a specific radio frequency is also considered in this work As studying results, it is found that the height of antenna to cover the detection ranges and the influences of detection ranges by weather environments can be analyse with the theoretical methods.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.4
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• pp.427-435
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• 2011

This paper deals with the measurement and analysis of the squeal noise according to the curvature of rail. The squeal noise is generated by the friction between the railway with curve and the wheel. The squeal noise is a big problem in Busan Metro Line 3. If the developing panel type ANC(Active Noise Control) system which is attached to the floor can reduce 5 dB in below 500 Hz, the sound pressure level of the whole band pass can be reduced about 4-4.8 dB in squeal noise above the curvature of R400. Curve squeal noise is the intense high frequency tonal that can occur when a railway vehicle transverses a curve. The frequency range is from around 500 to almost 20,000 Hz, with noise levels up to about 15 dB in curve.