• 지역사회간호학회지
• /
• 제28권1호
• /
• pp.55-68
• /
• 2017

Purpose: The purpose of this study is to develop and evaluate a joint health self-management program for knee osteoarthritis elders in communities. Methods: This program was developed based on the IMB (information-motivationbehavioral skills) model. The program methods include education, setting and achieving goals, sharing experiences, telephone counseling, and self-monitoring. The topics of the program include joint assessment, exercise, massage, joint protection, medication, depression management, diet, and healthcare approach. The research was conducted following the principles of the nonequivalent control group pretest-posttest design. Participants were 26 subjects in the experimental group, and 27 subjects in the control group. The experimental group participated in the self-management program, and the control group received general education. Results: Both post-test scores of personal motivation, social motivation, behavior skill, self-management behavior, joint pain, joint stiffness, physical function disability, right knee extension, left knee extension, and depression were significantly different between the experimental group and the control group. Conclusion: The results of the study can be used to develop and standardize a systematic joint health self-management program. Further research is highly recommended to develop a strategy to continuously facilitate self-management of osteoarthritis patients' procedures.

• Journal of Mechanical Science and Technology
• /
• 제16권6호
• /
• pp.799-809
• /
• 2002

In order to utilize a parallel mechanism as a machine tool component, it is important to estimate the errors of its end-effector due to the uncertainties in parts. This study proposes an error analysis for a new parallel device, a cubic parallel mechanism. For the parallel device, we consider two kinds of errors. One is a static error due to link stiffness and the other is a dynamic error due to clearances in the parts. In this study, we propose a stiffness model for the cubic parallel mechanism under the assumption that the link stiffness is a linear function of the link length. Also, from the fact that the errors of u-joints and spherical joints are changed with the direction of force acting on the link, they are regarded as a part of link errors, and then the error model is derived using forward kinematics. Lastly, both the error models are integrated into the total error, which is analyzed with a test example that the platform moves along a circular path. This analysis can be used in predicting the accuracy of other parallel devices.

• 한국자동차공학회논문집
• /
• 제3권6호
• /
• pp.96-111
• /
• 1995

A bellows is a component installed in the automobile exhaust system to reduce the impact from an engine. It's stiffness has a great influence on the natural frequency of the system. Therefore, it must be designed to keep the specified stiffness that requires in the system. This study present the finite element analysis of U-typed bellows using a curved conical frustum element and the shape optimal design with specified stiffness. The finite element analysis is verified by comparing with the experimental results. In the shape optimal design, the weight is considered as the cost function. The specified stiffness from the system design is transformed to equality constraints. The formulation has inequality constraints imposed on the fatigue limit, the natural frequencies, the buckling load and the manufacturing conditions. A procedure for shape optimization adopts a thickness, a corrugation radius, and a length of annular plate as optimal design variables. The external loading conditions include the axial and lateral loads with a boundary condition fixed at an end of the bellows. The recursive quadratic programming algorithm is selected to solve the problem. The result are compared with the existing bellows, and the characteristics of the bellows is investigated through the optimal design process. The optimized shape of the bellows are expected to give quite a good guideline to the practical design.

• Steel and Composite Structures
• /
• 제48권5호
• /
• pp.547-564
• /
• 2023

This study investigates the effect of bolt preloading on the rotational stiffness of stainless steel end-plate connections. An experimental programme incorporating 11 full-scale joint specimens are carried out comparing the behaviours of fully pre-tensioned (PT) and snug-tightened (ST) flush/extended end-plate connections, made of austenitic or lean duplex stainless steels. It is observed from the tests that the presence of bolt preloading leads to a significant increase in the rotational stiffness. A parallel finite element analysis (FEA) validated against the test results demonstrates that the geometric imperfection of end-plate has a strong influence on the moment-rotation response of preloaded end-plate connections, which is crucial to explain the observed "two-stage" behaviour of these connections. Based on the data obtained from the tests and FE parametric study, the performance of the Eurocode 3 predictive model is evaluated, which exhibits a significant deviation in predicting the rotational stiffness of stainless steel end-plate connections. A modified bi-linear model, which incorporates three key properties, is therefore proposed to enable a better prediction. Finally, the effect of bolt preloading is demonstrated at the system (structure) level considering the serviceability of semi-continuous stainless steel beams with end-plate connections.

• 한국터널지하공간학회 논문집
• /
• 제9권1호
• /
• pp.37-47
• /
• 2007

환경훼손 및 주거 과밀지역의 민원을 최소화할 목적으로 도심지 공사에서 쉴드터널공법의 적용이 날로 증대되고 있다. 쉴드터널의 주 구조체인 라이닝 세그멘트는 연속체가 아닌 이음부를 가지는 구조로 되어져 있다. 지금까지 설계실무에서는 라이닝 세그멘트의 구조해석 모델이나 설계하중 및 지반정수의 영향 등에 대한 별다른 검증 평가없이 과거의 국내 외 설계자료를 관행적으로 적용하고 있다. 본 연구에서는 국 내외에서 현재 사용하고 있는 쉴드터널의 세그멘트 해석 및 설계 모델들에 대해 이론해와 수치해의 비교를 통하여 적정성을 평가하였다. 그 결과, 사용의 편이성과 현장조건 의 적용성, 해석결과의 적용성 측면에서 전주면빔이음스프링 모델(1R-S0)을 제안하였다. 그리고, 제안된 모델을 이용하여 이음부 강성과 지반강성, 이음부 분할 분포 및 분할 개수 등에 대한 매개변수 해석을 수행하였다. 그 결과, 이음부를 갖는 라이닝 세그멘트에 발생하는 휨모멘트는 일정한 크기 이상의 지반강성에서 이음부가 없는 연속체의 라이닝 세그멘트에 발생하는 휨모멘트의 크기에 일정한 비율로 수렴함을 알 수 있었다. 또한, 이음부의 강성이 작을수록 측벽부에 비하여 천정부와 바닥부의 휨모멘트가, 수평변위에 비하여 수직변위가 이음부 분할 분포에 따라 큰 영향을 받는 것을 알 수 있었다.

• 한국운동역학회지
• /
• 제24권2호
• /
• pp.173-180
• /
• 2014

The purpose of this study was to investigate the effect of combined exercise on injury risk factors of lower extremity during landing. Ten sports talented athletes participated in this study. Sports talented athletes participated in a combined exercise (sports talented exercise, coordination) for 16 weeks. A three-dimensional motion analysis was performed using eight infrared cameras (sampling rate of 100 Hz), one force plate, and electromyography system (sampling rate of 1000 Hz) during landing. Kinetic, and kinematics analysis including average impulsive force, angle of lower extremity, vertical stiffness, onset of muscle activation were calculated by Matlab2009a software. Paired t-test was performed at alpha=.05. The average impulsive force in landing phase was not statistically significant (t=-.748, p=.474). The hip joint angle was more decreased in post test compared to pre test (E1: t=2.682, p=.025, E2: t=5.609, p=.000, E3: t=2.538, p=.032). The knee joint (E1: t=-.343, p=.739, E2: t=1.319, p=.220, E3: t=.589, p=.570) and ankle joint (E1: t=.081, p=.937, E2: t=.784, p=.453, E3: t=.392, p=.704) angle were tended to decrease after combined exercise. The vertical stiffness was tended to decrease after combined exercise (t=1.972, p=.080). Onset of quadriceps femoris (t=.698, p=.503) and medial gastocnemius (t=1.858, p=.096) were tended to be faster than biceps femoris (t=-.333, p=.747) after combined exercise. Although thses findings were not statistically significant except on a hip joint angle, risk factors of lower extremity such as joint angle, vertical stiffness and onset of quadriceps femoris, medial gastrocnemius were positively changed after the combined exercise but an additional training for improved onset of biceps femoris would be required in the future.

• 한국전문물리치료학회지
• /
• 제27권2호
• /
• pp.133-139
• /
• 2020

Background: The gastrocnemius (GCM) is one of the lower extremity muscles that tend to tighten easily. GCM tightness results in limited ankle dorsi-flexion (DF), especially when the knee joint is fully extended. Joint flexibility is determined by the morphological and physiological characteristics of joints, muscles, tendons, and ligaments. Impaired joint flexibility can be attributed to increased susceptibility to muscle injury. High-frequency diathermy is clinically used to reduce pain and muscle tightness and to improve limited range of motion. Objects: This study aimed to investigate the immediate effects of high-frequency therapy in subjects with GCM tightness. Methods: The study was designed as a one-group before-after trial. The subjects included 28 volunteers with GCM tightness (an active ankle DF angle of less than 12°) without any known neurological and musculoskeletal pathologies in the ankle and calf areas. WINBACK Transfer Electrode Capacitive and Resistive Therapy equipment was used to apply high-frequency therapy to the subjects' GCMs for 10-15 minutes. The pennation angle and the fascicle length of the GCM were measured using ultrasonography. The flexibility of the ankle joint, peak torque to the passive ankle DF (Biodex), and soft tissue stiffness (MyotonPRO) were also measured. Results: The pennation angle was significantly decreased following the treatment; however, no significant difference in the fascicle length was found (p < 0.05). The flexibility was significantly increased and both the passive peak torque to passive ankle DF and the soft tissue stiffness significantly decreased (p < 0.05). Conclusion: High-frequency therapy is immediately effective for improving the muscle's architectural properties and functional factors in subjects with GCM tightness. Further longitudinal clinical studies are required to investigate the long-term effects of high-frequency therapy on subjects with GCM tightness from various causes.

• Journal of the Korean Wood Science and Technology
• /
• 제19권1호
• /
• pp.22-30
• /
• 1991

This study was carried out to determine the Joint characteristic of L-type specimens. L-type specimens were made of two kinds uf solid woods(Antiaris, Sepetir) and three kinds of wood based materials(plywood, particleboard, medium density fiberboard). They were constructed with PVC anchor and screw, and were discussed with joint strength and stiffness coefficients. The obtained results were as follows: 1. Bending strength showed very high increasing rate from one to three used PVC anchor and screw but was a little rise from three to four used PVC anchor and screw in solid wood. However. in wood based materials, it was unchanged without increasing rate or slight decreased from three to four used PVC anchor and screw. 2. The stiffness coefficients, or Z-values, were in the range from $4.704\times10^{-4}$ to $1.864\times10^{-3}$(rad/kgf-cm). They showed $10^{-3}$ level in one PVC anchor and screw but $10^{-4}$ level in two, three. four PVC anchor and screw. Accordingly, they indicated flexible joints in one PVC anchor and screw and relatively stable joints in two, three. four PVC anchor and screw. 3. Measured ultimate bending moments were 258.70kgf-cm in plywood and 142.68kgf-cm in medium density fiberboard. 4. Comparing with dowel joint. the joint strength used PVC anchor screw was inferior to 8mm and 10mm dowel diameter but differ little from 6mm dowel diameter.

• 지질공학
• /
• 제12권3호
• /
• pp.345-360
• /
• 2002

이 연구는 활동 가능성이 높은 퇴적암 사면에 대한 안정성을 분석하기 위해 수치해석을 수행하고, 안정성을 확보할 수 있는 보강공법을 제시하기 위한 목적으로 수행되었다. 연구지역은 백악기 하양층군의 학봉 현무암층에 해당하는 지역으로 대부분이 현무암질 응회암으로 구성되어 있으며, 지질 구조요소로는 크게 1차 구조 요소인 층리와 2차 구조요소인 절리 및 단층이 확인되었다 층리는 단사구조를 보이는데, 대부분의 경우 경사방향이 120~160/15~25(dip direction/dip)이고, 절리의 경우에는 크게 3개 조의 절리군이 확인되는데 세트 1은 310~330/65~85, 세트 2는 230~250/70~85이며, 세트 3은 뚜렷한 연장성을 보이지는 않지만 020의 경사방향에 85$^{\circ}$이상의 고각을 보이고 있다. 사면에 대한 안정성 해석은 운동학적 해석과 한계평형 해석을 수행한 후, 수치해석 방법으로 FLAC을 이용하였다. FLAC은 유한차분법을 이용하는 연속체 역학모델이지만, Interfaces Module을 이용하여 UDEC과 같은 불연속체 모델의 해석효과를 얻을 수 있었다.

• 한국강구조학회 논문집
• /
• 제23권1호
• /
• pp.61-72
• /
• 2011

본 연구에서는 일체식교대 강교량 거더-교대 연결부의 강체거동 및 균열저항성능의 향상을 위한 구조상세를 제시하고 그에 따른 연결부의 거동을 실험적으로 평가하였다. 거더-교대 연결부의 강체거동 및 균열저항성능을 향상시키기 위하여 전단연결재 및 tie bar를 적용한 연결부를 제시하였으며, 제시된 연결부 실험체와 기존 시공경험에 의해 설계된 연결부 실험체의 하중재하실험을 통하여 연결부의 성능 및 거동 특성을 검토하였다. 하중재하실험 결과, 모든 강 거더-교대 연결부 실험체들은 목표 설계하중 및 항복하중 이하에서 충분한 강성 및 균열저항 성능을 보여 강 거더-교대 연결부로 적용 가능하다. 하지만 실험체의 초기 강성, 균열의 진전형상 측면, 하중-변형률 측면에서 전단연결재와 tie bar가 적용된 강 거더-교대 연결부가 기존에 적용되어 왔던 강 거더-교대 연결부에 비하여 구조적으로 우수한 것으로 판단된다.