• Journal of Biomedical Engineering Research
• /
• v.23 no.1
• /
• pp.17-26
• /
• 2002

The purpose of this study was to investigate the important Parameters of the Pedicle screw by estimating the mechanical characteristics of screws under static and dynamic loads. Methodology for estimating Parameters under static load was proposed. It was also shown that the fatigue life of the one-level system could be increased by changing the shape of screws. Load parameters of the single pedicle screw were friction force. bending moment. and holding force. The test results of the one-level system could be inferred from teat results of the sin91e screw under bending force Fatigue life of the one-level system with flexible rod was longer than that of the upper Part test without rod . Considering the drop of flexibility of the rod due to muscles and ligament, fatigue life of the one-level system could be estimated b? that of the single screw.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.5
• /
• pp.169-177
• /
• 2011

In this study, an impact resistance of concrete segmented composites adopted shell's structures which have the excellent impact resistance was assessed. In order to enhance the performances of concrete segmented composite, the bond strength of mortar between the concrete blocks should be improved. Hence, in this study polymer mortars were applied to increase the bond strength of mortar. From the results of bond tests, the 15% latex mortar was selected and static and low-velocity impact tests were carried out for the specimens applied the plain and latex mortar. The concrete segmented composites, of which the bond strength of mortar was enhanced, showed improved low-velocity impact resistances. A Nonlinear finite element analysis using the discrete crack model showed similar energy dissipating capacities to the impact test's results. Consequently, by improving the analysis models for segmented composites, the impact resistances for manifold variables can be predicted and assessed.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.5
• /
• pp.1320-1329
• /
• 1990

A static performance tester for a torque rod assembly was developed to evaluate the three characteristics of the rod rubber bushing : radial spring characteristic, thrust spring characteristic, and rotational torque characteristic. Among the various schemes considered in the conceptual design stage, the final versatile type was determined to perform three different tests in one machine. The performance testing machine carried out radial spring test, thrust spring test, and torque test of the torque rod assembly. Static performance of the torque rod assembly was evaluated with the tester developed and fatigue strength of the assembly was also tested with the servo-hydraulic structural fatigue testing machine. The life of the component was found to be related with the rubber quality and adhesionability between the rubber and the steel rod. The optimum rubber hardness was experimentally found by changing the chemical compositions of rubber, and the adhesion was improved by optimizing the shape of the outer section of a the rubber, this study ensured the development of a reliable torque rod assembly.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.8 s.239
• /
• pp.1061-1069
• /
• 2005

In part I of this papter Nonlinear Response Optimization using Equivalent Static Loads (NROESL) method/algorithm is developed to conduct optimization for nonlinear behavior structures. The method/algorithm is also verified to show its convergency and optimality. In this present paper, the NROESL algorithm is applied to several structural problems with geometric and/or material nonlinearity. Conventional optimization with sensitivity analysis using the finite difference method is also applied to the same examples. The results of the optimizations are compared. The proposed method is very efficient and derives good solutions.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.8 s.239
• /
• pp.1051-1060
• /
• 2005

Nonlinear Response Optimization using Equivalent Static Loads (NROESL) method/algorithm is proposed to perform optimization of non-linear response structures. The conventional method spends most of the total design time on nonlinear analysis. The NROESL algorithm makes the equivalent static load cases for each response and repeatedly performs linear response optimization and uses them as multiple loading conditions. The equivalent static loads are defined as the loads in the linear analysis, which generates the same response field as those in non-linear analysis. The algorithm is validated for the convergence and the optimality. The proposed algorithm is applied to a simple mathematical problem to verify the convergence and the optimality.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.11a
• /
• pp.561-562
• /
• 2007

• 전기의세계
• /
• v.39 no.12
• /
• pp.5-11
• /
• 1990

일상생활에서 우리가 정하는 대상중에 명확하게 그 소속을 정의 할 수 없는 경우가 많다. 이러한 대상들을 수학적으로 다루기 위하여 퍼지집합의 개념을 도입하였다. 이 퍼지집합 개념은 각 대상이 속한다, 안속한다라는 이원론적인 논리오부터, 각대상을 그 모임에 속하는 정도로 이해함으로써 일반화된 개념이다.

• Food Industry
• /
• s.110
• /
• pp.56-61
• /
• 1991

오늘날 세계 각국간에는 농산물의 무역이 점점 활발하여지고 있지만 그것에 따른 여러 가지 문제도 발생하고 있다. 그 중의 하나가 잔류농약의 문제인데, 제외국에 있어서 농산물 중의 잔류농약 기준치는 각국마다 달라 그것이 농산물의 수출, 수입에 따른 여러가지 문제의 원인으로 되고 있다. 특히 일본에서는 아래 2가지의 점 즉, 외국에서는 농약으로서 사용되고 있어 농산물 중의 잔류기준이 정하여져 있는데 일본에서는 기준이 없는 농약이 농산물 중에 잔류하는문제 및 수확 후 사용하는 농약의 잔류문제가 해결되어야 하는 중요한 과제이다. 이 문제해결을 위하여서는 제외국의 농약잔류규제, 잔류기준 설정의 방법 및 농산물 중의 잔류실태 등을 아는 것이 우선 필요할 것이다. 이러한 점에서 각국 및 국제기관에서 행하고 있는 농약규제의 사정에 대하여 알아보고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.1 s.244
• /
• pp.66-75
• /
• 2006

Nonlinear response structural optimization using equivalent static loads (NROESL) has been proposed. Nonlinear response optimization is solved by sequential linear response optimization with equivalent static loads which are generated from the nonlinear responses and linear stiffness matrix. The linear stiffness matrix should be obtained in NROESL, and this process can be fairly difficult for some applications. Proportional transformation of loads (PTL) is proposed to overcome the difficulties. Equivalent static loads are obtained by PTL. It is the same as NROESL except for the process of calculating equivalent static loads. PTL is developed for large-scale probems. First, linear and nonlinear responses are evaluated from linear and nonlinear analyses, respectively. At a DOF of the finite element method, the ratio of the two responses is calculated and an equivalent static load is made by multiplying the ratio and the loads for linear analysis. Therefore, the mumber of the equivalent static loads is as many as that of DOF's and an equivalent static load is used with the reponse for the corresponding DOF in the optimization process. All the equivalent static loads are used as multiple loading conditions during linear response optimization. The process iterates until it converges. Examples are solved by using the proposed method and the results are compared with conventional methods.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2010.07a
• /
• pp.43-46
• /
• 2010

전력산업분야는 스마트그리드 표준체계 및 고도화된 정보통신 인프라의 도입과 보안 그리고 분산전력 등에 대한 신기술 도입에 의해서 급격한 변화기를 맞이하고 있다. 현재 미국과 EU에서는 세계시장을 겨냥해서 스마트그리드의 국제표준화를 주도하고 있으며, 제3세계에서는 전력설비 시장의 지속적 성장이 예상되고 있다. 이에 국내에서도 국제 경쟁력 확보 및 신성장동력 창출을 목표로 연구가 진행 중이다. 전력체계의 운영망과 별개의 시험망 구성이 필요하며, 그 시험망을 통한 검증을 위해 시험망내 표준규격의 통신환경의 설계 및 기능검증은 매우 중요한 요소이다. 본 논문에서는 시험평가망 구성이후 평가를 위해 사용할 수 있는 주요 Component의 설계과정 중의 일부인 IEC 61850기반의 MMS 통신 환경구성 및 기능검증을 위한 연구결과에 대해 설명한다.