• 한국군사과학기술학회지
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• 제10권4호
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• pp.176-184
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• 2007

The missile for this study has shown different natural frequency characteristics depending on the test conditions; natural frequencies obtained from its flight test are higher than those in its ground test. It was found that the hinged joints connecting front airframe to rear one had the nonlinear stiffness and caused the missile to show very complex dynamic characteristics. The angular stiffness at hinged joints was calculated using 3D finite element analysis, and it was verified that there was a highly nonlinear relationship between angular stiffness and external load. Natural frequencies calculated considering the nonlinearity of angular stiffness were nearly the same as test results. Through this study, the dynamic characteristics of a missile having split airframes with hinged joints could be clearly identified and a way of maintaining its natural frequencies consistent was generated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.271-274
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• 2005

In this research, 13 RC slabs connected by hinged joints were tested. the new slab was connected to the existing slab by hinge joint injecting dowel bars between two slabs. Main parameters of the slabs were the spacing of the dowel bars (150mm, 300mm, and 450mm) and the locations of the longitudinal reinforcement of the old slab. The test results indicated that the joint strength of the RC test slabs having various types of dowel bars was about twice that calculated by the ACI 318-02 code. The locations of the longitudinal reinforcement of the old slab slightly increased the strength of the slabs connected by hinged joints.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.2983-2985
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• 1999

This paper presents the attitude control of the double inverted pendulum with compliant joint. The biped robot with compliant ankle joint instead of a motor have a good contact between it's sole and ground in the uneven ground. The compliant ankle joint proposed here is composed of springs and mechanical constraint. The lower link is hinged on the plate to free for rotation in the vertical plate. The upper link is connected to the lower link through a DC motor. The DC motor is used to control the posture of the pendulum by adjusting the position of the upper link. The algorithm for controlling a proposed inverted pendulum is nonlinear feedback controller. Simulation with mathematical model are conducted to show the validity of the proposed controller.

• 한국임상수의학회지
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• 제29권6호
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• pp.502-505
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• 2012

8개월령, 3.5 kg의 중성화하지 않은 토이 푸들이 왼쪽 다리의 체중 부중을 하지 않는 파행으로 내원하였다. 방사선 검사에서, 왼쪽 경골 근위부의 Salter-Harris II 형 성장판 골절과 비골 골절이 발견되었다. 교차핀, 긴장철사와 경첩 관절경유 외고정을 통해 근위 경골의 성장판 골절을 정복 하였다. 수술 후 1주째까지 경첩관절경유 외고정의 관절가동변위를 $25^{\circ}$, 수술 후 2주째까지 $70^{\circ}$ 까지 증가 시켰으며 수술 후 3주째 경첩 관절경유 외고정을 제거하였다. 수술 후 6주차에 골절은 합병증 없이 성공적으로 치유되었고 환자는 정상보행을 회복하였다. 수술 후 7개월째 환자는 정상적으로 보행을 하였으며, 반대쪽 정상다리와 비교하였을 때 관절의 가동범위는 동일 하였다. 본 증례는 근위 경골의 성장판 골절이 있는 미성숙견에서 교차핀, 긴장철사 및 경첩 관절경유 외고정을 이용하여 성공적으로 치료한 사례이다. 이러한 방법은 수술 후 골절정복의 안정성 및 조기 관절운동을 통한 정상 관절범위의 회복에 유용하게 사용 될 수 있을 거라 사료된다.

• Steel and Composite Structures
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• 제45권1호
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• pp.1-21
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• 2022

In the structural analysis of steel frames, joints are generally considered as rigid or hinged considering their moment transfer ability. However, the first studies conducted with the beginning of the 20th century showed that the joints do not actually fit these two definitions. In reality, a joint behaves between these two extreme points and is called semi-rigid. Including the actual state of the joint in the structural analysis provides significant economic advantages, so the subject is an intense field of study today. However, it does not find enough application area in practice. For this reason, a large-scale literature published from the first studies on the subject to the present has been examined within the scope of the study. Three important points have been identified in order to examine a joint realistically; modelling the load-displacement relationship, performing the structural analysis and how to design. Joint modelling methods were grouped under 7 main headings as analytical, empirical, mechanical, numerical, informational, hybrid and experimental. In addition to the moment-rotation, other important external load effects like axial force, shear and torsion were considered. Various evaluations were made to expand the practical application area of semi-rigid connections by examining analysis methods and design approaches. Dynamic behaviour was also included in the study, and besides column-beam connections, other important connection types such as beam-beam, column-beam-cross, base connection were also examined in this paper.

• 한국전산구조공학회논문집
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• 제13권4호
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• pp.427-436
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• 2000

이 논문은 불규칙 가진력을 받는 회전-고정보의 비선형 응답특성을 나타낸다. 불규칙 가진력은 두 번째 고유모드의 절점과 최대변위점에 가했다. 비선형 편미분 방정식과 경계조건으로 표현되는 이 문제를 Galerkin의 방법을 이용하여 연립 비선형 상미분방정식으로 변환하였다. 이 상미분방정식으로부터 Fokker-Planck방정식과 모멘트 방정식을 얻은 후 Gaussian closure 방법 및 non-Gaussian closure 방법을 이용하여 3 모드 근사시 각각 27개 및 209개의 자율 상미분방정식을 구하였다. Gaussian closure 방법과 non-Gaussian closure 방법으로 2 모드 및 3 모드 근사해석을 수행하였고 해석적 결과들은 Monte Carlo 시뮬레이션 결과와 비교되었다. 해석결과 2 모드 근사해와 3 모드 근사해가 거의 일치하였고 2 모드 내부공진만 고려하여도 해석결과에 별 영향을 주지 않는다는 것을 알 수 있다.

• 대한전기학회논문지:전력기술부문A
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• 제48권9호
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• pp.1147-1153
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• 1999

The attitude control of a double inverted pendulum with a periodical disturbance at link top is dealt in this paper. The proposed system is consisted of the double inverted pendulum and a disturbing link; a triple inverted pendulum with two motors. The lower link is hinged on the plate to free for rotation in the vertical plane. The upper link is connected to the lower link through a DC motor. The DC motor is used to control the posture of the pendulum by adjusting the position of the upper link. The periodical disturbance can be generated by the additional like attached at the end of link 2 through another DC motor, which is the modeling of a posture for a biped supporting with one leg. The motor for the joint simulates the knee joint(or hip joint) and the disturbance for the legs moving in air. The algorithm for controlling the proposed inverted pendulum which is regarded as a virtual double inverted pendulum with a periodic disturbance, is consisted of a state feedback control and a fuzzy logic controller connected in parallel. The fuzzy controller keeps the center of gravity of the biped within the specified range through the nonlinear feedback compensator. The state feedback control takes over the role to maintain a desired posture regardless the disturbance at the link top. Simulations with a mathematical model and experiments are conducted to show the validity of the proposed controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2309-2311
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• 1998

The attitude control of a double inverted pendulum with a periodical disturbance at link top is dealt in this paper. The proposed system is consisted of the double inverted pendulum and a disturbance link. The lower link is hinged on the plate to free for rotation in the vertical plane. The upper link is connected to the lower link through a DC motor. The DC motor is used to control the posture of the pendulum by adjusting the position of the upper link. The periodical disturbance can be generated by the additional link attached at the end of link 2 through another DC motor, which is the modeling of a posture for a biped supporting with one leg. The motor for the joint simulates the knee joint(or hip joint) and the disturbance for the legs moving in air. The algorithm for controlling a proposed inverted pendulum is consisted of a state feedback control and a fuzzy logic controller. The fuzzy controller keeps the center of gravity of the biped within the specified range through the nonlinear feedback compensator. The state feedback control takes over the role to maintain a desired posture regardless the disturbance at the link top. In these case, the change of the angle and COG of an upper link is compensated with on-line. Simulations with a mathematical model are conducted to show the validity of the proposed controller.

• 대한족부족관절학회지
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• 제14권2호
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• pp.146-150
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• 2010

Purpose: Pilon fracture has several serious complications such as joint stiffness, arthrosis and delayed angular deformity. We report short-term results of new treatment modality using distracted dynamic external fixators and early controlled ankle motion. Materials and Methods: Eight cases of severe pilon fractures for which we tried small plate fixation and additional distracted dynamic external fixators from July 2007 to June 2009 were included. Half passive continuous ankle joint motion was allowed under free hinged ring fixators after the operation. The external fixators were removed after two or three months from the surgery. We investigated joint space by radiograph, joint pain, range of motion, patient's satisfaction of treatment protocol. Results: Joints were distracted when external fixators were applied and mean 28% of space loss developed after removal of external fixators. In most of cases, satisfactory alignments were maintained. Regarding range of joint motion, mean dorsiflexion angle was 15 degrees and mean plantarflexion angle was 32 degree in the condition of wearing external fixators. There was mean 8% reduction of range of motion but no further progression of ankle stiffness after removal of external fixators. Dorsiflexion was not improved after that, but plantarflexion angle was improved 10% even after removal of external fixators. Patients were generally in compliance with the treatment protocols with high level of satisfaction. Conclusion: We got good results with distracted dynamic external fixators and early continuous half-passive joint motion for pilon fractures in terms of joint pain and range of motion. Therefore we suggest this new protocol as an alternative modality for severe pilon fractures.

• 제어로봇시스템학회논문지
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• 제5권5호
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• pp.577-584
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• 1999

In this paper, the double inverted pendulum having a single actuator is built and the controller for the system is proposed. The lower link of the target pendulum system is hinged on the plate to free for rotation in the specified range($10^{\cire}$) on the x-z plane. The upper link is connected to the lower link through a DC motor. The double inverted pendulum built can be kept upright posture by controlling the position of the upper link even though it has no actuator in lower hinge. The algorithm to control the inverted pendulum consists of a state feedback controller within a linearizable range and a fuzzy logic controller coupled with a nonlinear feedback compensator for the rest of the range. Conventional state feedback control is employed, and the fuzzy controller is responsible for generating the reference joint angle of the upper link for the nonlinear feedback compensator which drives a DC motor to generate an indirect torque to the lower joint. As a result, we can get the upright posture of the proposed pendulum system. Simulations and experiments are conducted to show the validity of the proposed controller.