• 한국정밀공학회지
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• 제30권8호
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• pp.815-823
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• 2013

The hot curvature forming of large aluminum plates is a process used to produce spherical liquefied natural gas (LNG) tanks. In this study, we describe a method to determine the optimum shape of blanks to minimize the root gap in the forming process. The method proposed in this study was applied to a small-scale model for thick plates with a curvature of 1500 mm and thickness of 6 mm. First, the shape of the curved shells was determined as the target shape, and then a coordinate transform was used to determine the optimum blank shape, which was then iteratively modified using the results of finite element method (FEM) simulations, including heat transfer, until the shape error was minimized. Experiments in forming using Al5083 thick plate were carried out, showing that the method can determine the optimum blank shape within an allowable root gap of 0.1 mm.

• 대한기계학회논문집B
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• 제22권11호
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• pp.1591-1602
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• 1998

Simple spanwise distribution models of deviation angle and pressure loss coefficient due to the tip leakage flow are formulated for use in association with the streamline curvature method as a flow analysis. Combining these new models with the previous deviation and loss models due to secondary flow, a robust streamline curvature method is established for flow analysis of single-stage, subsonic axial turbines with wide ranges of turning angle, aspect ratio and blading type. At the exit from rotor rows, the flow variables are mixed radially according to a spanwise transport equation. The proposed streamline curvature method is tested against a forced vortex type turbine as well as a free vortex type one. The results show that the spanwise variations of flow angle, axial velocity and loss coefficients at rotor exit are predicted with good accuracy, being comparable to a steady three-dimensional Navier-Stokes analysis. This simple and fast flow analysis is found to be very useful for the turbine design at the initial design phase.

• 한국정밀공학회지
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• 제1권3호
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• pp.71-84
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• 1984

This paper examined strain distribution and radius of curvature of the bulge by finite element method and investigated limit polar thickness strain to predict the formability of sheet metal as we substituted effective strain and the radius of curvature obtained by FEM into instability condition equation successively. In experiment, the radius of curvature and limit polar thickness strainwere obtained by Moire method. Also, a concent- ric set of photogrid circles was used to measure the strain of arbitrary point and mild steel was used as material. This results obtained are as follows: 1) The radius of curvature obtained by FEM is in good agreement with the Moire experimental value. 2) The polar thickness strain is getting larger as the inside is approached from the edge. This means that fracture occurred near the ploe. 3) The circumferential strains agree closely with the meridian strains and the polar thickness strain is about twice the circumferential (or meridian) strain. This result agrees with the fact that anisotropy coefficient (R-value) obtained by tensile test is about one. 4) The theoretical results of limit polar thickness strain obtained by authors' method are better agreement with experimental results than other theoretical results. Therefore, we can better predict the formability of sheet metal with authors' method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.879-880
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• 2010

• 한국공작기계학회논문집
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• 제13권6호
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• pp.34-40
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• 2004

This paper presents studies on curvature radius measurement using the laser interferometer. It is a general practice to measure to $10^{-10}$m in length with the recent improvement and innovations in measurement technology and the processor used. The measurement methods can generally be categorized as these two: the contactual method and non-contactual method; and in this study, we will find ways to lower the cost for a CMM, or a coordinate measurement machine, and try to find an alternative. Furthermore, we will discuss some of the ways to improve the non-contactual measurement methods-optical interferometer method and the optical triangulation method. We will measure an object using a laser distance measuring device and Set the Point-contact result with the ball-bearing type and line-contact result with the bearing type, to decide on which probe type will be used.

• 대한의용생체공학회:의공학회지
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• 제26권6호
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• pp.365-372
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• 2005

Topology optimization method has a great advantage and capability over a conventional shape optimization technique because it optimizes a topology as well as a shape and size of structure. The purpose of the present study, using topology optimization method with an objective function of minimum compliance as a mechanism of bone remodeling, is to examine which shape factors of femur is strongly related with the curvature of femoral shaft. As is expected, the optimized curvature increased definitely with neck angle among the shape factors and showed a similar trend with the measured curvature to neck angle. Therefore, the topology optimization method can be successfully applied in the analysis of bone remodeling phenomenon in the subsequent studies.

• Archives of Plastic Surgery
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• 제50권2호
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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.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제16권6호
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• pp.654-662
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• 2010

본 논문은 2단계 연속(cascade) 방법을 이용한 향상된 보행자/비보행자 인식 알고리즘을 제안한다. 인식을 위한 분류기로는 약한 분류기를 강한 분류기로 만드는 아다부스트 알고리즘을 적용하였다. 먼저 두 가지 특징벡터를 추출 한다: (i) 기존의 기울기 히스토그램(HOG) 특성과 (ii) 한 점이 가지는 곡률특성 네 가지를 이용한 곡률-HOG를 제안하고 이용하였다. 그 다음 훈련 영상을 통하여 두 가지의 특징 벡터에 대해 약한 분류기로부터 강한 분류기를 얻었으며, 인식은 입력 영상으로부터 하나의 특징을 선택하여 이미 만들어진 강한 분류기를 통하여 1차적인 인식과 오인식을 실시하며, 오인식된 영상에 대해 2차적인 특징을 투입하여 이에 해당하는 강한 분류기를 통하여 2단계 아다부스트 알고리즘을 적용하여 최종적인 인식결과를 얻는다. 두 가지의 서로 다른 특성 벡터를 이용하여 연속 방법에 의한 2단계 아다부스트 알고리즘을 적용한 결과 기존의 실험 방법보다 더 정확한 인식 결과를 얻을 수 있었다.

• 한국의류학회지
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• 제33권3호
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• pp.401-409
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• 2009

The shape of crotch area is very important to develop functional clothing as well as other ergonomic goods such as chair or saddle etc. However, it is inevitable that 3D scanned image of crotch would have missing part due to its folded shape including overlapping legs nearby. Therefore, the objectives of this research was to compare reconstruction methods of missing parts at crotch using seven dummies of real men's replicas. Two reconstruction methods adopted were kinds of 'fill- hole' in Rapidform 2004, one was 'smooth' and the other was 'curvature'. Each restored image was compared with the original shape of the dummies. As results, the average distance was 0.66mm between original and 'smooth' treated images and 0.59mm between original and 'curvature' treated, which was not statistically different. Average area of restored crotch region was $8740.04cm^2$ by 'smooth' method and $8405.02cm^2$ by 'curvature' method which is close to the original area of $8413.76cm^2$. Statistical difference was found between images of original and 'smooth' ones$(p=0.04^*)$. However, there was no difference between original and 'curvature' treated images, which indicates that 'curvature' method is more useful to fill the hole compared with 'smooth' method.

• Journal of Acupuncture Research
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• 제19권3호
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• pp.230-239
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• 2002

Kyphotic cervical curvature, straghtening is commonly caused by trauma, muscle spasm without trauma and wrong posture, etc. Objective : This study is performed to evaluate the clinical effect of neck pain associated with Kyphotic cervical curvatre on cervical x-ray lateral view. Methods : One of the many causes, We examined the patients with neck pain & upper back pain who visited to Department of Acupuncture & Moxibustion, Gumi Oriental Hospital of Kyung-San University from 16th June 1999 to 22th June 2000. Pre and post treatment, We evaluated the cervical angle, Jochumsen's method, VAS(visual analogue scale) and effective score of treatment. Results & Conclusion : 1. Kyphotic cervical curvature is mainly caused by wrong posture during long term, sudden trauma, etc. therfore, postcervical muscles and tendon are injuryed by strong stress. So, muscle imbalance and pain is occured. 2. On these cases, The improvement index for pre/post treatment showed 28/42, 10/15, 9/30, 28/42 degree in cervical angle. Jochumsen's method showed -1/+2, -9/-3, -5/-2, -1/+2mm. Afer treatment VAS is 2, 1, 1, 1 and effective score of treatment is above good. The results suggest that treatments of Oriental Medicine(Acupuncture & Moxibustion, Chu-Na, Cupping and Physical therapy) are effective methods for neck pain with kyphotic cervical curvature on cervical x-ray lateral view.