• 대한기계학회논문집A
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• 제24권3호
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• pp.661-666
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• 2000

Optimization of the elastic joint of train is performed according to the minimization of ten responses which represent driving safety and ride comfort of train and analyzed by using the each response se surface model from stochastic design of experiments. After the each response surface model is constructed, the main effect and sensitivity analyses are successfully performed by 2nd order approximated regression model as described in this paper. We can get the optimal solutions using by nonlinear programming method such as simplex or interval optimization algorithms. The response surface models and the optimization algorithms are used together to obtain the optimal design of the elastic joint of train. the ten 2nd order polynomial response surface models of the three translational stiffness of the elastic joint (design factors) are constructed by using CCD(Central Composite Design) and the multi-objective optimization is also performed by applying min-max and distance minimization techniques of relative target deviation.

• Structural Engineering and Mechanics
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• 제83권3호
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• pp.341-351
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• 2022

During bolted flange assembly, the contact stiffness of some areas of the joint surface may be low due to the elastic interaction. In order to improve the contact stiffness at the lowest position of bolted flange, the correlation model between the initial bolt pre-tightening force and the contact stiffness of bolted flange is established in this paper. According to the stress distribution model of a single bolt, an assumption of uniform local contact stiffness of bolted flange is made. Moreover, the joint surface is divided into the compressive stress region and the elastic interaction region. Based on the fractal contact theory, the relationship model of contact stiffness and contact force of the joint surface is proposed. Considering the elastic interaction coefficient method, the correlation model of the initial bolt pre-tightening force and the contact stiffness of bolted flange is established. This model can be employed to reverse determine the tightening strategy of the bolt group according to working conditions. As a result, this provides a new idea for the digital design of tightening strategy of bolt group for contact stiffness of bolted flange. The tightening strategy of the bolted flange is optimized by using the correlation model of initial bolt pre-tightening force and the contact stiffness of bolted flange. After optimization, the average contact stiffness of the joint surface increased by 5%, and the minimum contact stiffness increased by 6%.

• 터널과지하공간
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• 제6권1호
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• pp.19-29
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• 1996

Back analysis model, capable of calculating the mechanical properties and the in-situ stresses of jointed rock mass, was developed based on the inverse method using a continuum theory. Constitutive equation for the behavior of jointed rock contains two unknown parameters, elastic modulus of intact rock and stiffness of joint, hence algorithm which determines both parameters simultaneously cannot be established. To avoid algebraic difficulties elastic modulus of intact rock was assumed to be known, since the representative value of which would be quite easily determined. Then, the ratio ($\beta$) of joint stiffness to elastic modulus of intact rock was assigned and back analysis for the behavior of jointed rock was carried-out. The value $\beta$ was repeatedly modified until the elastic modulus from back analysis became very comparable to the predetermined value. The joint stiffness could be calculated by multipling the ratio $\beta$ to the final result of elastic modulus. Accuracy and reliability of back analysis procedure was successfully testified using a sample model simulating the underground opening in the jointed rock mass. Applicability of back analysis model for the underground excavation in practice was also verified by analyzing the mechanical properties of jointed rock in which underground oil storage cavern were under construction.

• 한국전문물리치료학회지
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• 제23권3호
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• pp.29-39
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• 2016

Background: In the treatment of temporomandibular joint (TMJ) disorder, the goals of traditional physical therapy are not only to reduce the inflammatory process leading to pain, but also to decrease joint overload and muscle hyperactivity. To achieve those goals, physical therapists generally use a photo-therapy, joint mobilization, and massage. Objects: To examine the impact of an unloading technique using non-elastic taping on the pain, opening mouth, functional level, and quality of life in patients with TMJ disorder. Method: Twenty patients with TMJ disorder were included in this study and randomly divided into the experimental ($n_1$=10), and control ($n_2$=10) groups. Traditional physical therapy including massage and stretching for 30 min was performed in both groups. Non-elastic taping was performed in the experimental group after traditional physical therapy, and they were recommended to keep the tape attached for 12 hours. Outcomes for pain, functional level, and quality of life were measured using a survey. The opening mouth was measured using a general ruler. Result: Significant differences were observed in the pain level, opening mouth, functional level, and quality of life after the intervention and on follow-up in both groups. However, we found that while the levels of all parameters were maintained throughout the follow-up period in the experimental group, the functional status level was not maintained throughout the follow-up period in the control group. Conclusion: Our unloading technique using non-elastic tape results comparable to those achieved by traditional physical therapy in the treatment of TMJ. However, the unloading taping method using non-elastic tape is more effective than traditional physical therapy in maintaining the impact of intervention.

• Structural Engineering and Mechanics
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• 제10권2호
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• pp.125-138
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• 2000

The paper analyzes the problem of torsion in an adhesive non-tubular bonded single-lap joint. The joint considered consists of two thin rectangular section beams bonded together along a side surface. Assuming the materials involved to be governed by linear elastic laws, equilibrium and compatibility equations were used to arrive at an integro-differential relation whose solution makes it possible to determine torsional moment section by section in the bonded joint between the two beams. This is then used to determine the predominant stress and strain field at the beam-adhesive interface (stress field along the direction perpendicular to the interface plane, equivalent to the applied torsional moment and the corresponding strain field) and the joint's elastic strain (absolute and relative rotations of the bonded beam cross sections). All the relations presented were obtained in closed form. Results obtained theoretically are compared with those given by a three dimensional finite element numerical model. Theoretical and numerical analysis agree satisfactorily.

• 대한물리의학회지
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• 제11권2호
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• pp.71-76
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• 2016

PURPOSE: The purpose of this study was to compare isometric contraction of deltoid middle fiber between elastic band and light dumbbell on various shoulder abduction angle. And this study intends to examine the compare with isometric contraction on deltoid middle fiber in various abduction angle of shoulder joint. METHODS: The participants of this study were Korean healthy adult in their 20s (n=60). The 8 channel surface electromyography was used to measure activity of the deltoid middle fiber at isomeric contraction on various abduction angle: $0^{\circ}$, $30^{\circ}$, $60^{\circ}$, $90^{\circ}$, $120^{\circ}$ of shoulder joint using elastic band: red color Theraband and dumbbell: 2kg. The data used in the analysis of the present study was the root mean square. RESULTS: The deltoid middle fiber activation was not significantly different between elastic band and dumbbell at each abduction angle. The deltoid middle fiber activation significantly increased as more to increased shoulder abduction angle in elastic band and dumbbell. CONCLUSION: The elastic band and dumbbell was to provide the similarly load to the deltoid middle fiber isometric contraction on all of the shoulder abduction angle. The deltoid middle fiber activation increased as more to increased shoulder abduction angle in elastic band and dumbbell. These results may be an important reference in development of exercise on shoulder joint.

• 근관절건강학회지
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• 제12권2호
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• pp.97-108
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• 2005

Purpose: The purpose of this study was to identify the effects of Self-help group program including Elastic band exercise on ADL and ROM of hemophilia patient. Method: A quasi -experimental design was used. The subjects were 40 young adults with hemophilia (21 experimental group, 19 control group). The subjects of experimental group were participated self-help group program in which five sessions for 5 weeks. The program consisted of health education on hemophilia, elastic band exercise, and therapeutic recreation and its outcomes have been evaluated on ADL and ROM of extremities. The obtained data were analyzed by using the Mann-Whitney U test and ANCOVA of SPSS. Result: 1) The score of ADL increased significantly in the experimental group as compared to the control group. 2) The degree of range of motion of extremities improved in the experimental group as compared to the control group. Conclusion: Considering these research results, the program including elastic band exercise was effective in improving self-management ability and range of motion of extremities. Therefore this program including elastic band exercise could be implemented it as self-management for the hemophilia clients.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.254-259
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• 1992

In this paper, we propose an optimal method for the tracking a trajectory of the end-effector of flexible robot arms with multiple joints. The proposed method finds joint trajectories and joint torques necessary to produce the desired end-effector motion of flexible manipulator. In inverse kinematics, optimized joint trajectories are computed from elastic equations. In inverse dynamics, joint torques are obtained from the joint equations by using the optimized joint trajectories. The equations of motion using finite element method and virtual work principle are employed. Optimal control is applied to optimize joint trajectories which are computed in inverse kinematics. The simulation of flexible planner manipulator is presented.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.688-693
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• 2007

Most frame structures cannot be manufactured in a single-piece form. Ideally, when a structure is built up by assembling multi pieces, assembly at the joints should be rigidly performed enough to have almost full stiffness, which is difficult for practical reasons such as manufacturing cost and time. In this research, we aim to develop a manufacturability-oriented compliance-minimizing topology optimization using a ground beam model incorporating additional zero-length elastic joint elements. In the present formulation, design variables control the stiffness of zero-length elastic joints, not the stiffness of beams. Because joint stiffness values at the converged state can be utilized to select candidate assembly locations and their strengths, the technique is extremely useful to design multi-piece frame structures. An optimal layout is also extracted based on the stiffness values.

• Structural Engineering and Mechanics
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• 제46권6호
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• pp.843-852
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• 2013

This paper presents results of the effect of different bolt tightening sequences and methods on the performance of gasketed bolted flange joint using nonlinear finite element analysis. Bolt preload scatter due to elastic interactions, flange stress variation and bolt bending due to flange rotation and gasket contact stress variation is difficult to eliminate in torque control method i.e. tightening one bolt at a time. Although stretch control method (tightening more than one bolt at time) eradicates the bolt preload scatter, flange stress variation is relatively high. Flange joint's performance is compared to establish relative merits and demerits of both the methods and different bolt tightening sequences.