• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 가을 학술발표회 논문집
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• pp.145-151
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• 1994

Welded connections have been designed on basis of allowable stresses, wherein the response to loading is assumed to be totally elastic. This is the vector analysis method, which resolves the stresses determined from the direct stress formula and the torsion formula into a vector combination to obtain a solution. It has been known that this method gives conservative answers and typically a very high factor of safety. An analytical method based on the Instantaneous Center of Rotation has been developed which predicts the ultimate strength of an eccentically loaded fillet welded connection. The method of Instantaneous Center of Rotation results in weld resistance capacities greater than the vector analysis method, by recognizing the variation in fillet weld strength with respect to the direction of the applied loading and actual load-deformation response of elemental fillet welds. The procedure of numerical analysis is iterative and complex. The relations between vector analysis method and the method of Instantaneous Center of Rotation on eccentrical distance subjected to variation of load direction are presented in this paper. Considering of the effects on configuration of weld groups, the method of Instantaneous Center of Rotation are provided a more exact results of the numerical analysis.

• 한국운동역학회지
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• 제19권4호
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• pp.779-791
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• 2009

본 연구의 목적은 원위지점에서 움직이는 실험 데이터를 이용하여 그 점들의 회전운동 순간 중심점을 분석하는 프로그램(Centering 1.0)을 개발하는 것이다. 이를 위해 수학적인 알고리즘을 정의하고, 물체의 운동에 대한 실험 데이터를 입력하여 회전운동 순간 중심점을 찾아내는 컴퓨터 프로그램을 구현하였다. 프로그램을 검증하기 위한 실험 데이터는 한명의 숙련된 여성골퍼의 피칭(40m 캐리)과 퍼팅(4m) 스트로크 시 클럽의 움직임으로 수집하였다. 그리고 이 데이터를 본 연구를 통해 개발된 회전운동 순간 중심점 분석 프로그램에 적용하여 클럽의 움직임 시 회전의 중심점을 찾고, 그 위치의 크기를 반지름으로 나타내었다. Centering 1.0 프로그램은 구간을 크게 정의할 때 반지름의 오차가 약간 있었으나, 구간을 작게 나눌수록 매우 근사치의 값을 제시하여주었다. 피칭과 퍼팅을 비교할 경우에 피칭의 반지름이 퍼팅보다 매우 작게 나타났으며, 퍼팅의 경우 중심의 위치는 인체 내에 있지 않고 최고 3m 외부에 위치하는 것으로 나타났다. Centering 1.0 프로그램은 회전운동에서 구한 데이터의 최소 3개만 입력하면 반지름 값을 알 수 있으며, 이것이 누적되면 회전운동 순간 중심점의 이동경로를 알 수 있다.

• 대한치과보철학회지
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• 제27권1호
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• pp.55-81
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• 1989

Recently the instantaneous center concept has been to understand the biomechanics by which a tissue derangement causes a mechanical derangement in human joint. Therefore, to understand the biomechanics of temporomandibular joint (T.M.J.) as a part of human joint, it is necessary to clarify the instantaneous center of rotation (I.C.R.) in the mandibular movement. Twenty male subjects without T.M.J. disorder and mandibular deviation during the mandibular movement were selected for this study. The habitual opening and closing paths were recorded on the paper of the sagittal metal plate by two pencil markers connected to the resin open clutch attached on the lower teeth, which was designed for this study. The coordinates of the 33-target points and the 109-anatomical landmarks were obtained using a Summagraphic digitizer connected to a 18AT computer. The original raw data of the opening and closing paths were smoothed by B-spline curve fitting technique and then the I.C.R. pathways were determined mathematically by the computer using algorithm for finding the I.C.R. of a planer rigid body model. Also the opening and closing movements of the mandible were simulated according to the determined I.C.R. The results obtained from this study were as follows. 1. At the early opening and the last closing, I.C.R's were almost distributed around the mastoid process outside the mandibular body without the presence in the region of the mandibular condyle. 2. The I.C.R. pathway showed variable patterns to each subject at the opening and closing movements. 3. The K constant with uniform pattern was obtained by the rotation angle times the radius, which was assumed to the index of the mandibular movement. 4. The opening and closing movements of the mandible were simulated by the I.C.R. pathways at the habitual opening and closing movements. 5. The mandibular condyle was rotated or translated accordng to the relative rotation angle and radius of the determinant factors of K contant.

• 건축구조
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• 제22권3호
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• pp.31-42
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• 2015

• 한국전문물리치료학회지
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• 제31권1호
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• pp.72-78
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• 2024

Background: Limitations of shoulder range of motion (ROM), particularly shoulder internal rotation (SIR), are commonly associated with musculoskeletal disorders in both the general population and athletes. The limitation can result in connective tissue lesions such as superior labrum tears and symptoms such as rotator cuff tears and shoulder impingement syndrome. Maintaining the center of rotation of the glenohumeral joint during SIR can be challenging due to the compensatory scapulothoracic movement and anterior displacement of the humeral head. Therefore, observing the path of the instantaneous center of rotation (PICR) using the olecranon as a marker during SIR may provide valuable insights into understanding the dynamics of the shoulder joint. Objects: The aim of the study was to compare the displacement of the olecranon to measure the rotation control of the humeral head during SIR in individuals with and without restricted SIR ROM. Methods: Twenty-four participants with and without restricted SIR ROM participated in this study. The displacement of olecranon was measured during the shoulder internal rotation control test (SIRCT) using a Kinovea (ver. 0.8.15, Kinovea), the 2-dimensional marker tracking analysis system. An independent t-test was used to compare the horizontal and vertical displacement of the olecranon marker between individuals with and without restricted SIR ROM. The statistical significance was set at p < 0.05. Results: Vertical displacement of the olecranon was significantly greater in the restricted SIR group than in the control group (p < 0.05). However, no significant difference was observed in the horizontal displacement of the olecranon (p > 0.05). Conclusion: The findings of this study indicated that individuals with restricted SIR ROM had significantly greater vertical displacement of the olecranon. The results suggest that the limitation of SIR ROM may lead to difficulty in rotation control of the humeral head.

• 대한산업공학회지
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• 제25권1호
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• pp.56-66
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• 1999

Shoulder joint is the most movable joint in human body with, at least, three degrees of freedom, since there are at least three bones and five joints involved in shoulder movement. Due to the complexity of the shoulder joint and the lack of appropriate anatomical data, modeling of the shoulder joint has been known to be extremely difficult. In many biomechanical models being used, shoulder joint is considered as a fixed point and it is also assumed that the shoulder joint does not noticeably move during the shoulder movement. However, such an assumption is not valid in real applications and causes inaccuracy, especially, in the area of workspace evaluation. The reachable area generated by a human becomes somewhat different from that of current models for those models fail to appropriately reflect the movement of shoulder joint's center of rotation. In this study, the location of the shoulder joint's center of rotation was obtained in relation to the location of humerus, on which a new model for reach envelope generation was developed for workspace evaluation. From the experiments conducted for three subjects, the initial location of the center of rotation was determined for each subject and subsequent changes in the instantaneous center of rotation were drawn as a function of flexion and abduction of the shoulder. Based on the regression analysis, the study suggested a new method for the generation of reach envelope. Comparisons were also made among real reach envelopes obtained from the experiment, the ones from the model, and the ones from the new method suggested in the study. As a result, the prediction errors incurred from the new method were significantly reduced when compared to the ones from the current approach.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.58-65
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• 2000

This study is concerned about the verification and the implementation of a mechanical model for the force system in end milling. The model is based on the relationship between the cutting forces and the chip thickness. The components of the model are based on the average cutting forces which are experimentally obtained. And, both instantaneous and average force system characteristics are described as a function of cut geometry and a feed rate. This model employed two specific cutting forces, instantaneous and average specific cutting force, and the models which obtained using two cutting forces were compared and analyzed. In this study, cutter deflection with respect to the center of rotation is considered, which is a major part of the tool run-outs. The effect of run-out on the cutting forces is also discussed. The relationships among the run-out parameters, cutting parameters and the resulting force system characteristics are presented. In all cases, for the down milling with a right hand helix cutter is considered.

• 대한치과보철학회지
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• 제29권2호
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• pp.161-175
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• 1991

To understand the biomechanics of the mandibular movement of the patients with T.M.J. disorder, it is necessary to analyze the mandibular movement by the least moving points of instantaneous center of rotation on computer screen. In this study, two subjects without T.M.J. disorder and with normal occlusion and few patients with T.M.J. disorder were selected for obtaining the processing data. The habitual opening and dosing movements were recorded by image recognition system of video and computer and then the mandibular movement and the least moving point were analyzed using computer program for image anaysis of specialized points. The results obtained were as follows: 1. The least moving points of control group during opening and dosing were dose to the mandibular foramen, but in the test group there were differences between two positions of the least moving points during opening and closing. 2. The variations of the least moving point were in the range of $0.02\sim0.05cm$ of X-coordinate and $0.07\sim0.10cm$ of Y-coordinate for control group, whereas in the range of $0.05\sim0.30cm$ of X-coordinate and $0.08\sim1.65cm$ of Y-coordinate for test group. 3. The index of variation during opening and dosing movements was shown in $0.8\sim1.0$ for the control group and in $0.56\sim2.6$ for the test group. 4. After the treatment of the test group No. 4 by occlusal splint the least moving point was dose to the mandibular foramen and the index of variation was changed from 25 to 05. 5. The tracing shape of the least moving point in the test group represented the irregularities compared to the control group. 6. The mandibular opening and dosing movements were simulated on the computer screen following the movement of the least moving point of instantaneous center of rotation.

• 한국강구조학회 논문집
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• 제24권2호
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• pp.199-206
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• 2012

비보강받침접합(Unstiffened Seated Connection, USC)은 시공의 편의성과 설치시의 안정성 및 경제성이 있는 단순접합의 한 종류이다. 비보강받침접합은 하부ㄱ형강과 상부ㄱ형강으로 구성되며 하부ㄱ형강은 보의 단부반력전체를 지지하며, 상부ㄱ형강은 보의 안정을 위하여 설치한다. 상부와 하부ㄱ형강은 볼트 또는 용접에 의해 보와 지지부재에 접합된다. 본 연구에서는 비보강받침접합의 용접강도에 대한 실용적인 설계절차와 함께 용접부의 편심계산시 탄성벡터법(EVM)과 순간회전중심법(ICM)으로 소요지압길이에 근거한 설계도표를 제안하였다. 또한 제안한 설계방법에 의한 용접강도를 AISC와 KBC기준에 따라 비교하였다.

• 한국운동역학회지
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• 제12권1호
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• pp.125-133
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• 2002

The purpose of this study was to develop a method for estimating 3-D coordinates of lower trunk muscles using orientation angles during a motion. Traditional 3-D motion analysis system with DLT technique was used to track down the locations of eight reference markers which were attached on the back of the subject. In order to estimate the orientations of individual lumbar vertebrae and musculoskeletal parameters of the lower trunk muscle, the rotation matrix of the middle trunk reference frame relative to the lower trunk reference frame was determined and the angular locations of individual lumbar vertebrae were estimated by partitioning the orientation angles (Cardan angles) that represent the relative angles between the rotations of the middle and lower trunks. When the orientation angles of individual intervertebral joints were known at a given instant, the instantaneous coordinates of the origin and insertion for all selected muscles relative to the L5 local reference frame were obtained by applying the transformation matrix to the original coordinates which were relative to a local reference frame (S1, L4, L3, L2, or L1) in a rotation sequence about the Z-, X- and Y-axes. The multiplication of transformation matrices was performed to estimate the geometry and kinematics of all selected muscles. The time histories of the 3-D coordinates of the origin and insertion of all selected muscles relative to the center of the L4-L5 motion segment were determined for each trial.