• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.655-660
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• 2000

This paper presents the construction of consistent coefficient matrix elements for jointed structures using the reduction of flexibility and mass matrices. The reduced flexibility coefficient matrix hat little structural complexity than Guyan's stiffness matrix reduction since the only element of the original matrix, corresponding to the selected nodal degrees of freedom, contributes. The proposed method was applied to building equivalent coefficient matrices for a clamp jointed structure in finite element modal analysis of a cantilevered beam. The theoretical analysis results were compared with those experimental modal analysis, Comparison of both shows good agreement each other.

• Structural Engineering and Mechanics
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• 제41권2호
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• pp.285-297
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• 2012

An inverse approach is presented for calculating the flexibility coefficient of open-side cracks in the cross sectional of beams. The cracked cross section is treated as a massless rotational spring which connects two segments of the beam. Based on the Euler-Bernoulli beam theory, the differential equation governing the forced vibration of each segment of the beam is written. By using a mathematical manipulation the time dependent differential equations are transformed into the static substitutes. The crack characteristics are then introduced to the solution of the differential equations via the boundary conditions. By having the time history of transverse response of an arbitrary location along the beam, the flexibility coefficient of crack is calculated. The method is applied for some cracked beams with solid rectangular cross sections and the results obtained are compared with the available data in literature. The comparison indicates that the predictions of the proposed method are in good agreement with the reported data. The procedure is quite general so as to it can be applicable for both single-side crack and double-side crack analogously. Hence, it is also applied for some test beams with double-side cracks.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.528-533
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• 1995

An analyical method is proposed to construct a clamp jointed structure as an equivalent stiffness matrix element in the finite element modal analysis of a complex beam structure. Static structural analysis was first made for the detail finite element model of the clamp joint. Utilizing the results of this analysis, the equivalent stiffness matrix element was buildup by using the flexibility influence coefficient method and Guyan condensation. The proposed method was applied to finite element modal analysis of a clamp jointed cantilever beam. And the finite element analysis results were compared to those experimental modal analysis. Comparison shows doog agreement each other Furthermore the effects of normal contact(or clamping) load on the equivalent stiffness matrix was also examined. The equivalent stiffness matrix showed little change in spite of the remakable increase in the contact load on the clamp joint.

• 한국운동역학회지
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• 제12권2호
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• pp.245-257
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• 2002

이 연구의 목적은 간단하고 실용적이며, 타당성, 신뢰성, 객관성이 높은 체전굴 유연성 측정 도구를 개발하는데 있으며, D여자 대학교의 스포츠학 전공 여대생 44명이 자발적으로 연구의 피검자로 참여하였다. 새 측정 도구의 신뢰도와 객관도 검사는 재검법의 평균 측정값을 사용하여 이원 혼합효과 모델에 의한 급내 상관 계수를 산출하였다. 검사자별 1차와 2차의 급내 상관 계수는 L은 R = .994, Y는 R=.993, 1차와 2차 검사의 L과 Y검사자간 급내 상관 계수는 R = .985, R=.986으로 모두 상관도가 아주 높은 것으로 나타났다. 새로 개발한 체전굴 측정 도구의 타당도 검증을 위하여 Leighton-flexometer-tests의 원리를 이용한 Takei 의 flexometer를 준거 검사 도구로 사용하였으며, 1차 검사와 2차 검사에서의 새로운 체전굴 유연성 측정 도구와 준거 검사 도구 측정값의 Pearson 적률 상관계수는 각각 r = .962와 r = .960로 1, 2차 검사 모두 아주 높은 상관도를 나타냈다. 결론적으로 본 연구에서 새로 개발한 체전굴 검사는 타당도, 신뢰도, 객관도가 매우 높고 실용적인 것으로 평가될 수 있음이 밝혀졌다.

• 한국산학기술학회논문지
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• 제19권7호
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• pp.214-221
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• 2018

본 연구의 목적은 노지감귤의 출하구조를 순별, 월별로 구분하여 분석한다. 이를 위해 노지감귤의 가격신축성함수를 추정, 분석함으로써 어떻게 출하조절을 하는 것이 노지감귤농가의 소득을 안정시키고, 증대시킬 수 있는지를 모색하고, 이에 따른 정책적 함축성을 도출하는 것이다. 노지감귤 출하물량 1% 증가에 따른 순별 가격신축성은 시기에 따라 상이하게 나타나고 있는데, 10월 하순에서 1월 초순까지의 하락폭이 큰 것으로 나타나 이 시기의 출하조절의 필요성이 크다. 품질이 떨어지는 해를 나타내는 더미변수인 DUM_Q의 부호는 (-)이고, 통계적으로 유의미한 결과를 보여주고 있다. 설날 연후 7일 이상이 2월에 들어있는 해를 나타내는 더미변수인 DUM02의 10월 초순부터 1월 하순까지의 부호가 (-)를 보이고 있다. 이는 설날이 1월에 있는 경우보다 2월에 있는 경우가 물량증대에 따른 하락폭이 크다는 것을 나타낸다. 노지감귤의 출하물량 1% 증대에 따른 월별 가격신축성은 상이하게 나타나고 있는데, 10월에서 12월까지의 하락폭이 큰 것으로 나타나 이 시기의 출하조절의 필요성이 요구된다. 품질이 떨어지는 해를 나타내는 더미변수인 DUM_Q의 부호는 (-)이고, 통계적으로 유의미한 결과를 보여주고 있다. 설날 연후 7일 이상이 2월에 들어있는 해를 나타내는 더미변수인 DUM02의 10월부터 1월까지의 부호가 (-)를 보이고 있다. 이는 설날이 1월에 있는 경우보다 2월에 있는 경우가 물량증대에 따른 하락폭이 크다는 것을 나타낸다. 그리고 순별 및 월별 가격신축성함수의 더미변수인 DOM_Q와 DUM02의 부호가 음(-)을 보인다는 것은, 품질이 좋은 해보다 품질이 나쁜 경우에, 그리고 설날이 1월에 있는 경우보다 2월에 있는 경우에 출하조절의 필요성이 더 중요함을 의미한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.831-836
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• 1994

This paper presents rational modeling and analysis method for complex structures with various structural joints. For modeling of structural joint, a general modeling technique is newly proposed by flexibility influence coefficient and inverse of flexibility matrix and static reduction concept which is applied to the retained DOFs(degrees of freedom) of detailed finite element model of struction joints. By this method,joint model with contact surface. which can not be reduced by the general reduction theory such as Guyan reduction theory ,can be reduced effectively. And in this method, the nonlinearity of the contact surface can be linearized within a proper range and the boundary effects of joint region can be excluded. Using the proposed method, screwed joint,glued joint and bolted joint are analyzed. And the effectiveness of the proposed method is verified by experiments.

• 대한물리치료과학회지
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• 제28권1호
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• pp.76-84
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• 2021

Background: In clinical practice, active knee extension (AKE) test has been widely used to measure hamstring flexibility. During the AKE test, the knee extension is repeated six times. The first five repetitions are considered as warm-up, and the sixth is used as baseline. In order to accurately measure the subject's inherent flexibility, warm-up trials have been proposed as mentioned above; but currently, the evidence is insufficient. Design: Cross-sectional study. Methods: Forty-three healthy adults participated in this study. The AKE was performed slowly after flexing the hip and knee joints by 90° in a supine position. The knee was extended as far as could be done without causing discomfort or pain. When reaching the end range, knee flexion was performed without stopping. As per standard protocol, the subjects performed the knee extension six times. Results: There was no significant difference between the AKE value in the first trial with those in the other five trials. During the repetitions, the average value in the group with higher flexibility tended to decrease and the Intraclass correlation coefficient gradually decreased. Conclusion: Successive repetitions of the AKE test can misrepresent an individual's inherent hamstring flexibility. In order to avoid a decrease in hamstring flexibility, it is strongly recommended that individuals with high initial hamstring flexibility avoid unnecessary repetitions of the AKE test.

• 한국수학교육학회지시리즈A:수학교육
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• 제47권4호
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• pp.421-436
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• 2008

Mathematics assessment doesn't mean examining in the traditional sense of written examination. Mathematics assessment has to give the various information of grade and development of students as well as teaching of teachers. To achieve this purpose of assessment, we have to search the methods of assessment. This paper is aimed to develop the open-ended problems that are the alternative to traditional test, apply them to classroom and analyze the result of assessment. 4-types open-ended problems are developed by criteria of development. It is open process problem, open result problem, problem posing problem, open decision problem. 6 grade elementary students who are picked in 2 schools participated in assessment using open-ended problems. Scoring depends on the fluency, flexibility, originality The result are as follows; The rate of fluency is 2.14, The rate of flexibility is 1.30, and The rate of originality is 0.11 Furthermore, the rate of originality is very low. Problem posing problem is the highest in the flexibility and open result problem is the highest in the flexibility. Between general mathematical problem solving ability and fluency, flexibility have the positive correlation. And Pearson correlational coefficient of between general mathematical problem solving ability and fluency is 0.437 and that of between general mathematical problem solving ability and flexibility is 0.573. So I conclude that open ended problems are useful and effective in mathematics assessment.

• Computers and Concrete
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• 제25권3호
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• pp.273-282
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• 2020

A new seismic design methodology for precast concrete diaphragms has been developed and incorporated into the current American seismic design code. This design methodology recognizes that diaphragm inertial forces during earthquakes are highly influenced by higher dynamic vibration modes and incorporates the higher mode effect into the diaphragm seismic design acceleration determination using a first mode reduced method, which applies the response modification coefficient only to the first mode response but keeps the higher mode response unreduced. However the first mode reduced method does not consider effects of diaphragm flexibility, which plays an important role on the diaphragm seismic response especially for the precast concrete diaphragm. Therefore this paper investigated the effect of diaphragm flexibility on the diaphragm seismic design acceleration for precast concrete shear wall structures through parametric studies. Several design parameters were considered including number of stories, diaphragm geometries and stiffness. It was found that the diaphragm flexibility can change the structural dynamic properties and amplify the diaphragm acceleration during earthquakes. Design equations for mode contribution factors considering the diaphragm flexibility were first established through modal analyses to modify the first mode reduced method in the current code. The modified first mode reduced method has then been verified through nonlinear time history analyses.

• 대한물리치료과학회지
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• 제27권1호
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• pp.9-17
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• 2020

Background: This study aimed to examine the repeatability of hamstring strength during maximal voluntary contractions (MVCs) and to examine the sex difference. Design: Quasi-experiment design. Methods: The study recruited 23 healthy young individuals as participants. Hamstring flexibility was measured before and after MVCs by active knee extension test. Five trials of MVCs were performed, and hip extension forces were measured using a strain gauge during MVCs. Repeatability was confirmed by intraclass correlation coefficient (ICC) and coefficient of variation, and the difference between male and female participants was confirmed by independent samples t-test. Results: The forces measured during MVCs were significantly different between men and women over five trials. We observed the minimum and maximum force production at the first and fifth trial of MVCs in both men and women. Excellent to moderate reliability of the hamstring strength during MVCs was found in men (ICC range, 0.70-0.98) and women (ICC range, 0.66-0.90). There was no significant difference in hamstring flexibility between men and women. Conclusion: In clinical settings, we recommend excluding the first trial of MVCs in both men and women. Additionally, performing at least three trials of MVCs would be useful to improve the reliability of the baseline measures in women.