• 한국전산유체공학회지
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• 제20권1호
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• pp.39-46
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• 2015

In this research, we studied the pressure drop affecting on the internal surface roughness and the curvature radius of a U-tube, which is used for the cooling system in PWR(Pressurized Water Reactor). Using ANSYS-FLUENT, a commercial code based on CFD(Computational Fluid Dynamics) technique, we compared a Moody chart with the Darcy friction factor changed by a range of various surface roughness and Reynolds numbers of a straight pipe model. We studied the effect giving variation about a range of various surface roughness and the curvature radius of the full scale U-tube model. The material of the heat transfer tube is Inconel 690 used in the steam generator. We compared the velocity distribution of selected 4 locations, and derived the correlation between the surface roughness and the pressure drop for the U-tube of each representative curvature radius using the linear regression method.

• 한국정보과학회논문지:시스템및이론
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• 제34권4호
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• pp.132-137
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• 2007

평면상에서 이동하는 자동차와 같은 로봇은 이동방향을 변경할 때 제한된 곡률(curvature)로 서서히 방향을 바꿀 수밖에 없다. 본 논문은 물체의 동선의 곡률이 제한되어 있을 경우, 한 구성에서 출발하여 목표점에 이르는 최단경로는 CC 혹은 CS 타입(C는 원호(circular arc), S는 선분(line segment)을 의미한다), 혹은 이들의 부분문자열 타입이 된다는 사실을 기하학적 성질만을 이용하여 증명하였다. 본 연구결과를 이용하여, 시작점 구성에서 출발하여 목표점, 혹은 목표다각형에 도달하는 최단경로는 다각형의 공간복잡도의 선형시간에 계산 가능하다.

• 한방재활의학과학회지
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• 제21권4호
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• pp.97-109
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• 2011

Objectives: To investigate the correlation among cervical curvature, neck pain, and headache in patients with chronic neck pain. Methods: A clinical study was carried out in 48 chronic neck pain patients in the hospital of Gang-Dong Kyung-Hee University. The curvature of the cervical spine was measured by 3 types of measuring methods, Neck pain and headache were estimated using questionnaire and visual analogue scale (VAS). Results: Curvature angles of the cervical spine had significant positive correlation with the neck pain and headache, and headache can be estimated by cervical curvature using linear regression. Conclusions: The results suggests that the cervical curvature of chronic neck pain patients has a positive correlation with the nock pain and headache, and cervical curvature will be a posible preditor of chronic tension-type headache in patients with chronic neck pain.

• 대한기계학회논문집A
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• 제27권6호
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• pp.1014-1019
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• 2003

A dynamic modeling method for beams undergoing overall rigid body motion is presented in this paper. Two special deformation variables are introduced to represent the stretching and the curvature and are approximated by the assumed mode method. Geometric constraint equations that relate the two special deformation variables and the cartesian deformation variables are incorporated into the modeling method. By using the special deformation variables, all natural as well as geometric boundary conditions can be satisfied. It is shown that the geometric nonlinear effects of stretching and curvature play important roles to accurately predict the dynamic response when overall rigid body motion is involved.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.324-330
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• 2005

The flexural strength and ductility capacity of reinforced concrete columns are largely dependent on the amount of transverse steel. However, current design code does not specify the confinement effect of transverse steels in strength calculation. A non-linear moment-curvature analysis of RC column sections was conducted in order to develop PM interaction diagram considering transverse reinforcement effects. In this paper, a more reasonable application method of PM interaction diagram considering transverse steel amounts is introduced and proposed, based on moment-curvature non-linear analysis. Also, we proposed simplified method to use. easily in practical design.

• Earthquakes and Structures
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• 제10권3호
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• pp.629-643
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• 2016

Among all the natural disasters, earthquakes are the most destructive calamities since they cause a plenty of injuries and economic losses leaving behind a series of signs of panic. The present study highlights the moment-curvature relationships for the structural elements such as beam and column elements and Non-Linear Static Pushover Analysis of RC frame structures since it is a very simplified procedure of non-linear static analysis. The highly popular model namely Mander's model and Kent and Park model are considered and then, seismic risk evaluation of RC building has been conducted using SAP 2000 version 17 treating uncertainty in strength as a parameter. From the obtained capacity and demand curves, the performance level of the structure has been defined. The seismic fragility curves were developed for the variations in the material strength and damage state threshold are calculated. Also the comparison of experimental and analytical results has been conducted.

• 한국광학회지
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• 제16권5호
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• pp.423-427
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• 2005

본 연구는, 원리적인 다양한 장점에도 불구하고 현실적인 제약으로 인해 실제 설계과정에서 잘 적용되지 않는, 자이델 3차 수차를 간편하게 다룰 수 있는 방안을 제안한다. 먼저 유한 물체거리를 갖는 2 반사경계에 대해 자이델 3차의 구면수차계수를 유도한다. 여기서, 유도된 구면수차계수는 고차의 비선형 방정식으로 표현되는데, 그 구성은 설계변수(물체거리, 주경 및 부경의 곡률, 주경과 부경 사이의 거리)와 유효초점거리로 이루어진다. 해석적으로 표현된 고차의 비선형 구면수차 방정식은 컴퓨터를 이용한 수치기법에 의해 근사적인 제로조건을 만족하도록 풀려진다. 이렇게 구해진 다양한 수치 해들을 주의 깊게 통찰하면 주경과 부경의 곡률 간에 선형성이 존재함을 파악할 수 있다. 즉, 결과적으로 주경과 부경의 곡률들을 선형맞춤(linear fitting)하면 곡률선형방정식이 얻어지는데, 이의 의미는 약간의 대수적인 계산으로 최적화의 초기 입력 데이터를 손쉽게 얻을 수 있는 가능성을 제시한 것이다. 한편, 응용외의 순수 수차론적인 관점에서 본다면, 본 연구의 특징은 유한 물체거리를 갖는 2 반사경계의 주경 및 부경의 곡률들이 구면수차가 거의 제로가 되는 조건 하에서 상호간에 선형 관계가 존재하였다는 것이다.

• Communications for Statistical Applications and Methods
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• 제11권3호
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• pp.575-582
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• 2004

We explore the structure and usefulness of CERES plot as a basic tool for dealing with curvature as a function of the new predictor in generalized linear models. If a predictor has a nonlinear effect and there are nonlinear relationships among the predictors, the partial residual plot and augmented partial residual plot are not able to display the correct functional form of the predictor. Unlike these plots, the CERES plot can show the correct form. This is illustrated by simulated data.

• 대한수학회보
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• 제59권3호
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• pp.789-799
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• 2022

We establish a sharp integral inequality related to compact (without boundary) linear Weingarten hypersurfaces (immersed) in a locally symmetric Einstein manifold and we apply it to characterize totally umbilical hypersurfaces and isoparametric hypersurfaces with two distinct principal curvatures, one which is simple, in such an ambient space. Our approach is based on the ideas and techniques introduced by Alías and Meléndez in [4] for the case of hypersurfaces with constant scalar curvature in an Euclidean round sphere.

• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 하계학술발표회
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• pp.32-33
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• 2005