• Structural Engineering and Mechanics
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• 제11권1호
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• pp.1-16
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• 2001

This paper discusses the elastic stability of unbraced frames under non-proportional loading based on the concept of storey-based buckling. Unlike the case of proportional loading, in which the load pattern is predefined, load patterns for non-proportional loading are unknown, and there may be various load patterns that will correspond to different critical buckling loads of the frame. The problem of determining elastic critical loads of unbraced frames under non-proportional loading is expressed as the minimization and maximization problem with subject to stability constraints and is solved by a linear programming method. The minimum and maximum loads represent the lower and upper bounds of critical loads for unbraced frames and provide realistic estimation of stability capacities of the frame under extreme load cases. The proposed approach of evaluating the stability of unbraced frames under non-proportional loading has taken into account the variability of magnitudes and patterns of loads, therefore, it is recommended for the design practice.

• 대한수학교육학회지:학교수학
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• 제15권4호
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• pp.723-742
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• 2013

본 연구는 초등학교 5학년 학생들을 대상으로 수학 학습에 비구조화된 문제의 해결활동을 적용하여 문제 해결 과정에 나타난 초등학생의 비례적 추론 과정을 분석하여 학생들의 비례적 추론 수준과 형태의 특징을 알아보는 것을 목적으로 하였다. 연구 결과 학생들은 주어진 비구조화된 문제를 해결하면서 모둠별로 다양한 양상으로 비논리적(illogical) 접근, 덧셈적(additive) 접근, 곱셈적(multipicative) 접근, 함수적(functional) 접근의 비례적 추론 수준과 형태를 나타내었다. 또한 학생들은 비구조화된 문제를 [문제 이해하기]-[해 구하기]-[적용하기]의 과정을 통해 해결하면서 [양의 인식]-[비례적 관계 발견]-[비례적 관계 확장]의 흐름으로 비례적 추론의 모습을 나타냈다. 학생들로 하여금 실생활에서의 비, 비례 상황에서 여러 가지 양들을 비례적으로 추론할 기회를 갖도록 하여 비례적 추론을 발전시킬 수 있도록 해야 할 것이다.

• 드라이브 ㆍ 컨트롤
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• 제13권3호
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• pp.47-52
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• 2016

This paper presents a control method for the performance improvement of a proportional solenoid actuator using a Pulse Width Modulation (PWM) signal. It is very difficult to obtain excellent response performance from a proportional solenoid actuator using a simple proportional controller with no PWM signal or dither because the mass and structure of a proportional solenoid actuator changes according to the application target, friction force in the proportional solenoid tube, operating force and displacement range. To solve the above problems, first, a controller with a PWM function for experimenting with attraction force characteristics was designed and manufactured. Secondly, an experimental setup for solenoid performance measurement with a force sensor and a displacement sensor was also manufactured. The attraction force characteristics according to the frequency and duty ratio variations of a PWM signal were tested and the relationships among the frequency, duty ratio, plunger mass and friction characteristics were analyzed. Finally, response characteristics improvements for proportional solenoid actuators are discussed.

• Communications for Statistical Applications and Methods
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• 제18권4호
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• pp.485-493
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• 2011

The proportional likelihood ratio order is an extension of the likelihood ratio order for the non-negative absolutely continuous random variables. In addition, the Lindley distribution has been over looked as a mixture of two exponential distributions due to the popularity of the exponential distribution. In this paper, we first recalled the above concepts and then obtained various properties of the Lindley distribution due to the proportional likelihood ratio order. These results are more general than the likelihood ratio ordering aspects related to this distribution. Finally, we discussed the proportional likelihood ratio ordering in view of the weighted version of the Lindley distribution.

• 음성과학
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• 제12권1호
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• pp.65-74
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• 2005

The aim of this paper is to suggest an index of coarticulation, proportional undershoot values, given the observation that absolute undershoot within a language tends to be proportional to target-locus difference. The target-locus proportionality predicts that a large difference between the consonant locus and the vowel target will result in a large amount of vowel undershoot, while a small difference a small amount of vowel undershoot. It turns out that the proportional undershoot is a potentially more appropriate way of comparing degree of undershoot across languages. However, even though the proportional undershoot measurement may provide a useful index comparing the overall coarticulation degree in a CV token for cross-linguistic data, it is concluded that it may potentially wrongly predict the cases of transfer or error as a progress in learning.

• 한국정밀공학회지
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• 제10권3호
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• pp.125-132
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• 1993

On this study, magnetic force versus input currents is analyzed by modeling taper plunger type proportional electromagnet of ISC valve using the permernce method. And, the reliabiliy of simulation is verified by comparing the experimental values with the calaulate magnetic force. From the result of this study, it is found that the taper angles at plunger and core, the length of air gap between plunger and yoke are the prumary factors in designing taper plunget type proportional electromagnet. Magnetic force is decreased as a whole according to increasing the air gap between pluger and yoke, and vise versa. But, the magnetic force is not proportional to current, when the air gap is very small. In case of decreasing the taper angle of pluger, the stroke range of plunger where magnetic force is proportional to current becomes farther from core.

• 대한수학교육학회지:학교수학
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• 제9권4호
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• pp.447-466
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• 2007

본 연구에서는 학생들이 비례적 추론 문제에서 어떠한 어려움을 겪고 있는지, 어떠한 문제해결전략을 사용하는지를 구체적으로 살펴보고, 현행 교과서의 문제점은 무엇인지 등을 조사하여 이를 바탕으로 6-가 단계 '비례식' 단원에 관한 지도 프로그램을 개발하여 학생들의 비례적 추론에 대한 개념변화를 알아보고자 하였다. 먼저 학생들 대상의 검사지를 분석해 본 결과, 학생들은 비례적 상황 문제에서 취약함을 보였다. 이에 따라 연구자가 제작한 프로그램을 초등학교 6학년 학생들에게 적용해보고 상중하 수준에 따른 학생들의 변화를 알아보았다. 또한 실험반과 비교반의 학생들의 상중하 수준에 따른 비례추론의 특성을 비교하였다.

• 대한수학교육학회지:수학교육학연구
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• 제27권4호
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• pp.791-810
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• 2017

본 연구는 비례 추론에서 형식적 절차의 기계적 사용에 대한 비판과 이에 대한 대안으로 제시되는 시각적 모델의 사용에 대한 연구를 바탕으로 비례 추론 수업에서 시각적 모델의 활용 가능성을 탐색했다. 이를 위해 6학년 2학기 비례식과 비례배분 단원을 비표, 이중수직선, 이중테이프 모델을 활용한 수업으로 구성하여 한 학급에 적용하였다. 그 결과 시각적 모델이 비례의 의미를 이해하고 비의 성질 및 비례식의 성질을 발견하는 데, 그리고 비례식 문제 및 비례배분 문제를 해결하는 데 중요한 역할을 할 수 있음을 알 수 있었다. 또한 이러한 시각적 모델을 활용하는 데 학생들이 겪는 어려움과 이를 지도할 때 유의할 점이 있음을 확인하였다. 이를 통해 시각적 모델을 적극적으로 활용한 교과서 개발 및 비례 추론 수업에 대한 지도 방안을 마련하는 데 시사점을 제공할 수 있기를 기대한다.

• Steel and Composite Structures
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• 제47권2호
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• pp.289-296
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• 2023

The failure of a thin-walled tube was studied in this paper based on three failure models. Both proportional and non-proportional loading paths were applied. Proportional loading consisted of combined tension-torsion. Cyclic non-proportional loading was also applied. It was a circular out-of-phase axial-shear stress loading path. The third loading path was a combination of a constant internal pressure and a bending moment. The failure models under study were equivalent plastic strain, modified Mohr-Coulomb (Bai-Wierzbicki) and Tearing parameter models. The elasto-plastic analysis was conducted using J2 criterion and nonlinear kinematic hardening. The return mapping algorithm was employed to numerically solve the plastic flow relations. The effects of the hydrostatic stress on the plastic flow and the stress triaxiality parameter on the failure were discussed. Each failure model under study was utilized to predict failure. The failure loads obtained from each model were compared with each other. The equivalent plastic strain model was independent from the stress triaxiality parameter, and it predicted the highest failure load in the bending problem. The modified Mohr-Coulomb failure model predicted the lowest failure load for the range of the stress triaxiality parameter and Lode's angle.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.468-473
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• 1993

Augmented proportional navigation requires the information of a target acceleration, which must be estimated by a filtering logic. The process necessary accompanies a time lag, which degrades the guidance performance. A trade-off study between augmented and conventional proportional navigation is conducted with the time lag taken into consideration. The result shows that the conventional proportional navigation has better performance against a target maneuver in the missile-target coplane, while the augmented has better performance against out-of-coplane maneuver.