• 대한치과교정학회지
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• 제31권1호
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• pp.15-24
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• 2001

원하는 형태의 치아이동을 얻기 위해서는 M/F(Moment/Force) ratio의 조절이 필요하며, 이출 위해서는 치아의 저항중심의 위치를 아는 것은 매우 중요한 일이다. 본 연구에서는 실제 치아주위 환경을 비교적 유사하게 재현할 수 있는 치조골상과 치아의 이동을 시뮬레이션하는 장치를 제작하고, LVDT출 이용한 3차원 운동을 실시간으로 측정할 수 있는 시스템을 사용하여, 힘에 대한 3차원 공간상에서의 치주인대 응력 분포 양상 및 치아 저항중심과 회전축의 위치변화를 계측한 결과 다음과 같은 결론을 얻었다. 1. 상악 견치에 원심방향으로 힘을 가했을 때, 치아의 저항중심의 위치는 힘의 크기와는 무관하였으며, 치근의 치경부측 약 $29\%$ 부위에 위치하였다. 이는 2차원 모형($42\%$) 보다 치관 쪽에 위치한다. 2. 모멘트만 가하는 경우 치아의 저항중심과 회전축은 일치하였다. 3. 치아에 가해지는 모멘트가 증가하는 경우 방향에 관계없이 치아는 정출되는 경향을 보였다. 4. 힘이 가해진 위치, 저항중심, 회전축간에는 일정한 관계가 성립했다 (a x b = $49.6\;mm^2$). 이 관계식을 통해서 수평력이 가해질 때 예상되는 치아운동 양상을 알 수 있다. 5. 수평력이 가해질 때 회전축의 위치는 일직선으로 나타난다.

• 대한물리치료과학회지
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• 제8권1호
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• pp.893-906
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• 2001

The purposes of this study were to compare pelvic tilt. range of motion(ROM) of hip rotation, and leg length difference before and after manipulation and to investigate correlation between changes of each variables after manipulation of sacroiliac pint in 31 low back pain patients(11 males, 20 females) with sacroiliac pint dysfunction. The sacroiliac pint of patients was manipulated on the side of anterior pelvic tilt, using the technique described by Stoddard(1962) and Greenmann (1996). I used this technique because it usually eliminated sacroiliac Pint dysfunction in one treatment session. SPSS for window computer system was used to analyze the data. Also t-test was performed for comparison of the variables before and after manipulation, and Pearson product-moment correlation analysis and regression analysis were performed for changes of each variables after manipulation. The result were as follows: 1. The pelvic tilt after manipulation was significantly decreased(mean=$2.79^{\circ}$) compared with the pelvic tilt before manipulation(p=.001). 2. The PROM of hip internal rotation ipsilateral to anterior pelvic tilt after manipulation significantly decreased (mean = $1.88^{\circ}$) compared with hip internal rotation before manipulation (p=.008). The PROM of hip internal rotation ipsilateral to posterior pelvic tilt after manipulation significantly increased(mean = $1.29^{\circ}$) compared with hip internal rotation before manipulation (p=.029). 3. The PROM of hip external rotation ipsilateral to anterior pelvic tilt after manipulation significantly increased(mean=$2.42^{\circ}$) compared with the hip external rotation before manipulation(p=$2.42^{\circ}$) compared with the hip external rotation ipsilateral to posterior pelvic tilt after manipulation significantly decreased(mean = $1.84^{\circ}$) compared with the hip external rotation before manipulation (p=.008). 4. Leg length difference after manipulation significantly decreased(mean=2.15 mm) compared with leg length difference before manipulation (p=.008). Regression analysis revealed that a fair correlation was found between change in leg length difference and change in anterior pelvic tilt after manipulation(p=.009). 5. Pearson product-moment correlation coefficient was used to assess differences of the variables after manipulation. A fair correlation was found between change in leg length difference and change in anterior pelvic tilt after manipulation(r=.462, p<.01). A fair correlation was found between change in anterior pelvic tilt and change in hip internal rotation ipsilateral to anterior pelvic tilt(r=.397, p<.05) and between change in anterior pelvic tilt and change in hip external rotation ipsilateral to anterior pelvic tilt(r=.516, p<.01). A fair correlation was found between change in posterior pelvic tilt and changes in hip internal rotation ipsilateral to posterior pelvic tilt (r=.441, p<.05) and between change in posterior pelvic tilt and change in hip external rotation ipsilateral to posterior pelvic tilt(r=.361, p<.05). A fair correlation was found between change in hip internal rotation ipsilateral to anterior pelvic tilt and change in hip external rotation ipsilateral to posterior pelvic tilt(r=.388, p<.05) and between change in hip internal rotation ipsilateral to posterior pelvic tilt and change in hip internal rotation ipsilateral to anterior pelvic tilt(r=.426. p<.05).

• Steel and Composite Structures
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• 제15권6호
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• pp.705-724
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• 2013

The behaviour of steel column at elevated temperature is significantly different than that at ambient temperature due to its changes in the mechanical properties with temperature. Reported literature suggests that steel column may become vulnerable when exposed to fire condition, since its strength and capacity decrease rapidly with temperature. The present study aims at investigating the lateral load resistance of non-insulated steel columns under fire exposure through finite element analysis. The studied parameters include moment-rotation behaviour, lateral load-deflection behaviour, stiffness and ductility of columns at different axial load levels. It was observed that when the temperature of the column was increased, there was a significant reduction in the lateral load and moment capacity of the non-insulated steel columns. Moreover, it was noted that the stiffness and ductility of steel columns decreased sharply with the increase in temperature, especially for temperatures above $400^{\circ}C$. In addition, the lateral load capacity and the moment capacity of columns were plotted against fire exposure time, which revealed that in fire conditions, the non-insulated steel columns experience substantial reduction in lateral load resistance within 15 minutes of fire exposure.

• Steel and Composite Structures
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• 제32권1호
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• pp.141-156
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• 2019

This paper presents the flexural behaviour of stainless steel beam-to-tubular column joints with extended endplates subjected to static loading. Moment-rotation relationships were investigated numerically by using Abaqus software with geometric and material nonlinearity considered. The prediction of damages among components was achieved through ductile damage models, and the influence of initial geometric imperfections and residual stresses was evaluated in large fabricated stainless steel joints involving hollow columns and concrete-filled columns. Parametric analysis was subsequently conducted to assess critical factors that could affect the flexural performance significantly in terms of the initial stiffness and moment resistance. A comparison between codes of practice and numerical results was thereafter made, and design recommendations were proposed for further applications. Results suggest that the finite element model can predict the structural behaviour reasonably well with the component damage consistent with test outcomes. Initial geometric imperfections and residual stresses are shown to have little effect on the moment-rotation responses. A series of parameters that can influence the joint behaviour remarkably include the strain-hardening exponents, stainless steel strength, diameter of bolts, thickness of endplates, position of bolts, section of beams and columns. AS/NZS 2327 is more reliable to predict the joint performance regarding the initial stiffness and moment capacity compared to EN 1993-1-8.

• Steel and Composite Structures
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• 제22권1호
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• pp.141-159
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• 2016

Commonly in steel frames, steel beam and concrete slab are connected together by shear keys to work as a unit member which is called composite beam. When a composite beam is subjected to positive bending, flexural strength and stiffness of the beam can be increased due to "composite action". At the same time despite these advantages, composite action increases the strain at the beam bottom flange and it might affect beam plastic rotation capacity. This paper presents results of study on the rotation capacity of composite beam connected to Rectangular Hollow Section (RHS) column in the steel moment resisting frame buildings. Due to out-of-plane deformation of column flange, moment transfer efficiency of web connection is reduced and this results in reduction of beam plastic rotation capacity. In order to investigate the effects of width-to-thickness ratio (B/t) of RHS column on the rotation capacity of composite beam, cyclic loading tests were conducted on three full scale beam-to-column subassemblies. Detailed study on the different steel beam damages and concrete slab damages are presented. Experimental data showed the importance of this parameter of RHS column on the seismic behavior of composite beams. It is found that occurrence of severe concrete bearing crush at the face of RHS column of specimen with smaller width-to-thickness ratio resulted in considerable reduction on the rate of strain increase in the bottom flange. This behavior resulted in considerable improvement of rotation capacity of this specimen compared with composite and even bare steel beam connected to the RHS column with larger width-to-thickness ratio.

• 한국지진공학회논문집
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• 제13권5호
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• pp.51-60
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• 2009

안전한 내진설계를 위해서는 각 부재에 요구되는 소성변형 요구량을 정확히 예측하여야 한다. 본 연구에서는 등가정적내진설계에 쉽게 활용할 수 있도록, 복잡한 비선형해석 없이 탄성해석을 사용하여 모멘트골조 부재의 소성변형을 평가하는 방법을 개발하였다. 각 부재의 소성변형은 부재 강성과 탄성해석 결과로부터 직접 결정되는 층간변위비 요구량 및 모멘트 재분배 등의 설계 변수로부터 결정된다. 제안된 방법을 8층 2경간의 모멘트골조에 적용하고, 비선형해석을 통하여 제안된 방법의 정확성을 검증하였다. 검증결과, 제안된 방법은 비선형거동에 의한 층간변위비 요구량과 각 부재의 소성변형 요구량을 정확히 평가하였다. 제안된 방법은 부재연성설계와 같은 신축건물의 내진설계에 활용할 수 있을 뿐만 아니라 기존건물의 내진성능평가에도 활용될 수 있을 것으로 기대된다.

• 대한전자공학회논문지SP
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• 제40권6호
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• pp.149-156
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• 2003

본 논문에서는 변형 Otsu 이진화 방법, Hu 모멘트 및 선형 판별 분석(linear discriminant analysis, LDA)를 기반으로 밝기, 명암도, 크기, 회전 위치 변화에 강인한 얼굴 인식 방법을 제안하고자 한다. 제안한 변형 Otsu 이진화를 사용하여 밝기 및 명암도에 불변한 이진 영상들을 만든다. 그런 후 생성된 얼굴 영상의 경계 영상 및 다단계 이진영상으로부터 총 17개의 Hu 모멘트를 계산한 다음 LDA 방법을 적용하여 최종 특징 벡터를 추출한다. 특히 제안하는 얼굴 인식 방법은 Hu 모멘트를 이용함으로써 크기, 회전 및 위치 변화에도 강인한 특성을 갖고 있다. Olivetti research laboratory (ORL) 데이터베이스와 AR 데이터베이스의 총 100명의 얼굴 영상에 대해 기존의 주요 성문 분석(Principal component analysis, PCA) 방법 및 PCA와 LDA를 결합한 얼굴 인식 방법과 비교 실험한 결과, 제안한 얼굴 인식 방법은 대체적으로 기존 방법보다 뛰어난 인식 성능을 보였다.

• Steel and Composite Structures
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• 제7권2호
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• pp.87-103
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• 2007

This paper presents some of the results from an experimental research project on the behavior of extended end-plate connections subjected to moment conducted at the Structural Laboratory of Jordan University of Science and Technology. Since the connection behavior affects the structural frame response, it must be included in the global analysis and design. In this study, the behavior of six full-scale stiffened and unstiffened cantilever connections of HEA- and IPE-sections has been investigated. Eight high strength bolts were used to connect the extended end-plate to the column flange in each case. Strain gauges were installed inside each of the top six bolts in order to obtain experimentally the actual tension force induced within each bolt. Then the connection behavior is characterized by the tension force in the bolt, extended end-plate behavior, moment-rotation relation, and beam and column strains. Some or all of these characteristics are used by many Standards; therefore, it is essential to predict the global behavior of column-beam connections by their geometrical and mechanical properties. The experimental test results are compared with two theoretical (equal distribution and linear distribution) approaches in order to assess the capabilities and accuracy of the theoretical models. A simple model of the joint is established and the essential parameters to predict its strength and deformational behavior are determined. The equal distribution method reasonably determined the tension forces in the upper two bolts while the linear distribution method underestimated them. The deformation behavior of the tested connections was characterized by separation of the column-flange from the extended end-plate almost down to the level of the upper two bolts of the lower group and below this level the two parts remained in full contact. The neutral axis of the deformed joint is reasonably assumed to pass very close to the line joining the upper two bolts of the lower group. Smooth monotonic moment-rotation relations for the all tested frames were observed.

• 한국통신학회논문지
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• 제28권11C호
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• pp.1140-1151
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• 2003

본 논문에서는 변형 Otsu 이진화 방법과 Hu 모멘트를 기반으로 밝기, 명암도, 크기, 회전, 위치 변화에 강인한 얼굴 인식 방법을 제안한다. 제안하는 변형 Otsu 이진화 방법은 기존의 Otsu 이진화 방법으로부터 또 다른 문턱치 값을 결정하고 이로부터 얻어진 이진 얼굴 영상 2개를 사용함으로써 이진 영상 하나보다 고차원의 특징벡터를 추출할 수 있고, 기존의 Otsu 이진화 방법과 마찬가지로 밝기 및 명암도 변화에 강인한 속성을 가지고 있다. 특징 값으로는 Hu 모멘트를 사용함으로써 크기, 회전, 위치 변화에 강인한 특성을 추가로 가지고 있다 기존의 주요 성분 분석(Principal Component Analysis, PCA) 방법과 제안한 방법을 비교 실험한 결과, 위에서 언급한 5가지 다양한 환경 변화에 대하여 PCA 방법의 평균 인식률은 olivetti Research Laboratory (ORL) 데이터베이스와 AR 데이터베이스에 대해서 각각 68.4%와 51.2%이고, 제안한 방법의 평균 인식률은 각각 93.2%와 81.4%로서 제안한 방법의 인식 성능이 우수함을 확인하였다.

• 한국운동역학회지
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• 제23권1호
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• pp.85-90
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• 2013

Efficient gait is compensate for a lack of exercise, but the wrong walking can cause disease that joints, muscles, brain and body structure(Scott & Winter, 1990). Also many researchers has been studied gait of positive mechanism using analytical methods kinetic, kinematic. This study is to identify nature of knee adduction moment, depending on different foot progression angle and the movement of rotation of pelvis and body. Health study subject conducted intended walking with three different angles. The subjects of this study classified three types of walking; walk erect, pigeon-toed walk and an out-toed gait. Ten university students of K without previous operation and disease record selected for this study. For accuracy of this study, three types of walking carried out five times with 3D image analysis and using analysis of ground reaction force to analyze nature of knee adduction moment and the movement of rotation of pelvis and body. Firstly, the HC(heel contact) section value of intended walk erect, pigeon-toed walk and an out-toed gait was not shown statistically significant difference but TO(toe off) section value was shown that the pigeon-toed walk statistically significant. The value of pigeon-toed walk was smallest knee adduction moment(p< 0.005). Secondly, X axis was the change of rotation movement body and pelvis when walk erect, pigeon-toed walk and an out-toed gait. Shown statistically Y axis was not shown statistically significant but Z axis statistically significant(p<0.05). These result show the significant differences on TO section when walking moment reaches HC, it decides the walking types and rotates the foot.