• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
• /
• pp.337-344
• /
• 2001

This paper is concerned with the change of joint rigidity in estimating the degree of semi-rigidity of connections and the buckling load in a single layer latticed dome. The estimations are based on information about the ratio for the rotational stiffness of the connection to the flexural stiffness of the member and the minimum eigenvalue of a structure for pinned, semi-rigid and completely rigid cases, respectively. Connection characteristics are reflected in the ratio control of joint rigidity for the DOFs to be related using the spring element by FEM.

• 한국공간구조학회논문집
• /
• 제6권2호
• /
• pp.85-92
• /
• 2006

본 연구에서는 철근콘크리트 프리캐스트 대형판의 접합부 설계방법 및 해석방법에 대해서 연구를 수행하였다. 접합부의 설계방법은 수평접합부와 수직접합부의 구조적 거동에 대한 안정성 및 일체성을 확보하기 위한 설계법을 제시하였고, 접합부의 해석은 강체스프링 모델에 의한 탄소성해석을 수행 하였다.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 1998년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
• /
• pp.131-138
• /
• 1998

Structural damage is used to be modeled through reductions in the stiffness of structural elements for the purpose of damage estimation of structural system. In this study, the concept of joint damage is employed for more realistic damage assessment of a steel structure. The joint damage is estimated damage based on the mode shape informations using neural networks. The beam-to-column connection in a steel frame structure is represented by a rotational spring at the fixed end of a beam element. The severity of joint damage is defined as the reduction ratio of the connection stiffness with respect to the value of the intact joint. The concept of the substructural identification is used for the localized damage assessment in a large structure. The feasibility of the proposed method is examined using an example with simulated data. It has been found that the joint damages can be reasonably estimated for the case with the measurements of the mode vectors subjected to noise.

• 로봇학회논문지
• /
• 제9권1호
• /
• pp.11-19
• /
• 2014

In this paper, an external torque estimation problem in one-degree-of-freedom (1-DOF) flexible-joint robot equipped with a joint-torque sensor is revisited. Since a sensor torque from the joint-torque sensor is distorted by two dynamics having a spring connection, i.e., motor dynamics and link dynamics of a flexible-joint robot, a model-based estimation, rather than a simple linear spring model, should be required to extract external torques accurately. In this paper, an external torque estimation algorithm for a 1-DOF flexible-joint robot is proposed. This algorithm estimates both an actuating motor torque from the motor dynamics and an external link torque from the link dynamics simultaneously by utilizing the flexible-joint robot model and the Kalman filter estimation based on random-walk model. The basic structure of the proposed algorithm is explained, and the performance is investigated through a custom-designed experimental testbed for a vertical situation under gravity.

• 한국전산구조공학회논문집
• /
• 제35권6호
• /
• pp.343-349
• /
• 2022

본 논문에서는 구조물이 다중 구조물로 연결되는 경우 연결부의 조인트 위치를 기존의 위상최적설계 기법을 활용해 설계하는 기법을 개발하였다. 조인트는 길이가 0이고 강성이 매우 강한 스프링으로 모델링되었으며, 조인트는 유한요소 메시 형상과 무관하게 이동할 수 있도록 모델링되었다. 최적화 과정에서 조인트가 서로 뭉치는 현상을 방지하기 위해 조인트 최소거리 조건을 추가해 조인트간의 최소거리가 확보된 설계를 얻었다. 최적설계 시 목적함수로는 전체 구조물의 compliance 값이 사용되었으며, 조인트 최소거리 조건에 따른 결과를 비교하기 위해 2개의 수치예제를 해석하였다. 위상최적설계 결과 조인트 최소거리 조건의 변화에 따라 조인트 및 구조물의 최적 형상을 얻을 수 있었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권8호
• /
• pp.487-494
• /
• 2000

This paper describes the design, fabrication and experiments of surface-micromachined aluminum micromirror array with hidden pin-joints. Instead of the conventional elastic spring components as connection between mirror plate and supporting structure, we used pin-joint composed of pin and staples to support the mirror plate. The placement of pin-joint under the mirror plate makes large active surface area possible. These flexureless micromirrors are driven by electrostatic force. As the mirror plate has discrete deflection angles, the device can be ap;lied to adaptive optics and digitally-operating optical applications. Four-level metal structural layers and semi-cured photoresist sacrificial layers were used in the fabrication process and sacrificial layers were removed by oxygen plasma ashing. Static characteristics of fabricated samples were measured and compared with modeling results.

• 한국지진공학회논문집
• /
• 제2권1호
• /
• pp.35-46
• /
• 1998

대부분의 손상도 추정법들을 부재의 손상을 해당부재의 평균적인 강성감소로 표현하였다. 본 연구에서는 보다 실제적인 손상도를 추정하기 위하여, 접합부의 손상을 도입하였다. 접합부의 모형화를 위하여 보의 양단에 회전스프링을 추가하였으며, 접합부 손상을 접합부 강성의 감소로 정의하였다. 접합부의 손상도를 계측된 모드벡터를 바탕으로하여, 신경망기법을 추정하였다. 효율적인 훈련패턴을 만들기 위하여 Latin Hypercube Sampling 기법을 도입하였으며, 국부영역에서의 손상도추정을 위하여 부구조법을 도입하였다. 제안된 기법의 효율성을 검증하기 위하여 10층 프레임구조물에 대한 수치해석결과를 이용하였다. 예제해석을 통하여 추정결과가 상당히 정확함을 확인하여, 실제 적용 가능한 방법임을 알수 있었다.

• 한국지진공학회논문집
• /
• 제3권3호
• /
• pp.9-20
• /
• 1999

프레임 구조물의 접합부 손상을 평가하기 위하여 접합부 손상모델과 신경망기법을 이용한 손상평가기법을 제안하였다 구조물의 보-기둥 접합부를 접합부의 회전강성을 갖는 등가의 스프링요소로 표현하였으며 접합부의 손상도는 손상 전 후의 고정도계수의 감소비율로 정의하였다 손상평가를 위하여 다층퍼셉트론즈 신경망 기법을 제안하였으며 손상평가성능을 향상시키기 위하여 부분구조추정법, 노이즈첨가학습, 자료교란법등의 기법을 적용하였다 10층 프레임 구조물에 대한 수치 예제해석과 2층 프레임 구조물에 대한 실험 예제해석을 통하여 제안기법의 유용성을 평가하였다 계측지점이 일부분으로 제한되어 있고 계측자료에 심한 계측오차가 포함되어 있는 경우에도 손상평가가 합리적으로 이루어질수 있음을 알 수 있었다.

• Steel and Composite Structures
• /
• 제18권5호
• /
• pp.1305-1330
• /
• 2015

The successful application of the component-based approach - widely used to model structural joints - requires knowledge of the mechanical properties of the constitutive joint components, including an appropriate assembly procedure to derive the joint properties. This paper presents a component-method model for a structural joint component that is located in the tension zone of blind-bolted connections to concrete-filled tubular steel profiles. The model relates to the response of blind-bolts with headed anchors under monotonic loading, and the blind-bolt is termed the "Extended Hollo-bolt". Experimental data is used to develop the model, with the data being collected in a manner such that constitutive models were characterised for the principal elements which contribute to the global deformability of the connector. The model, based on a system of spring elements, incorporates pre-load and deformation from various parts of the blind-bolt: (i) the internal bolt elongation; (ii) the connector's expanding sleeves element; and (iii) the connector's mechanical anchorage element. The characteristics of these elements are determined on the basis of piecewise functions, accounting for basic geometrical and mechanical properties such as the strength of the concrete applied to the tube, the connection clamping length, and the size and class of the blind-bolt's internal bolt. An assembly process is then detailed to establish the model for the elastic and inelastic behaviour of the component. Comparisons of model predictions with experimental data show that the proposed model can predict with sufficient accuracy the response of the component. The model furthers the development of a full and detailed design method for an original connection technology.

• Journal of Plant Biology
• /
• 제5권2호
• /
• pp.13-16
• /
• 1962

Without annual ring, the bamboo can not measured by ordinary mensuration method. Other methods yet tried failed to prove the reliability. That means, as often pointed out, that the bamboo lumbering (including forest management) is not free from being precarious. Noting the fact, this author performed a serieds of comparative observations on a group of bamboos in different stages of growth in order to find out if there is any surer mensurability. A conclusion has been reached that the external feature of joints of branch has close connection with the age of bamboo, that the joints of the third major branch counting from the ground have, as shown in the first table, the most probability, its mean being 94.3 per cent, and that those in ages of 3 to 5 have the probability of 100 per cent, showing the far greater accuracy as compared with those in older ages. The above conclusion needs to be adjusted with the following findings; 1) When observed disregarding the joint-tongue(the remainder of the preceeding year's sheath), the major branches show no better probability than the minor ones. 54 to 78 per cent of them shows no difference between them. Probability is averaged by 60 per cent. 2) When in spring the old sheaths drop away from the joints, the new ones sprout out in their places and consequently the joints present an appearance of a kind of joint-ring. But since this joint-ring does not always exactly represent the plant age, some other method must be sought after to count the age. This author noticed what is called "joint-tongue" the tongue-like part of triangle shape which remains at the base of the sheath of the fallen leaf. A fact was ascertained that when the number of the joint-ring coincides with that of the remaining joint-tongue, it exactly indicates the age of the plant.the plant.