• 한국재료학회:학술대회논문집
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• 한국재료학회 1997년도 한국재료학회 춘계학술발표회
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• pp.114-114
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• 1997

• Structural Engineering and Mechanics
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• 제5권5호
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• pp.507-521
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• 1997

The ultimate behavior of a reinforced concrete hyperbolic paraboloid saddle shell under uniformly distributed vertical load is investigated using an inelastic, large displacement finite-element program originally developed at North Carolina State University. Unlike with the author's previous study which shows that the saddle shell possesses a tremendous capacity to redistribute the stresses, introducing tension stiffening in the model the cracks developed are no longer through cracks and formed as primarily bending cracks. Even though with small tension stiffening effect, the behavior of the shell is changed markedly from the one without tension stiffening effect. The load-deflection curves are straight and the slope of the curves is quite steep and remains unchanged with varying the tension stiffening parameters. The failure of the shell took place quite suddenly in a cantilever mode initiated by a formation of yield lines in a direction parallel to the support-to-support diagonal. The higher the tension stiffening parameters the higher is the ultimate load. The present study shows that the ultimate behavior of the shell primarily depends on the concrete tensile characteristics, such as tensile strength (before cracking) and the effective tension stiffening (after cracking). As the concrete characteristics would vary over the life of the shell, a degree of uncertainty is involved in deciding a specified ultimate strength of the saddle shell studied. By the present study, however, the overload factors based on ACI 318-95 are larger than unity for all the cases studied except that the tension stiffening parameter is weak by 3 with and without the large displacement effect, which shows that the Lin-Scordelis saddle shell studied here is at least safe.

• 박물관보존과학
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• 제23권
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• pp.61-70
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• 2020

금성산 고분군에 위치한 의성 대리리 2·3호분의 발굴조사 과정에서 마구류 주변으로 형태와 용도를 추정하기 어려운 회백색의 유기물이 확인되는 바, 회백색 유기물에 대한 실체현미경 분석을 실시하였다. 그 결과, 회백색의 유기물은 백화된 쌀겨 부식물임을 확인하였다. 마구류, 특히 안장의 아래에서 전면적으로 깔려 출토된 정황과 분석 결과를 근거로 용도를 추정해 본 결과, 안장 아래에 놓여서 말등과의 마찰을 줄이는 안장깔개의 충진재로 쌀겨가 사용되었음을 유추해 볼 수 있다. 충전재인 쌀겨를 제외한 상호관계의 유기물이 남아있지 않아 정확한 형태와 구조는 확인할 수 없으나 본 연구를 통해 쌀겨가 마구류와 함께 출토된 사례가 다양하게 보고된다면 쌀겨의 정확한 용도에 대해 면밀히 검토해 볼 수 있는 계기가 될 것으로 기대한다.

• 한국운동역학회지
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• 제24권4호
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• pp.417-423
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• 2014

The purpose of this study was to compare two saddle height determination methods by the effectiveness of pedal reaction force. Ten male subjects (age: $24.0{\pm}2.4years$, height: $175.1{\pm}5.4cm$, weight: $69.3{\pm}11.1kg$, inseam: $77.8{\pm}4.5cm$) participated in three minutes, 60 rpm cycle pedaling tests with the same load and cadence. Subject's saddle height was determined by $25^{\circ}$ knee flexion angle (K25) when the pedal crank was at the 6 o'clock position (knee angle method) and 97% (T97), 100% (T100), 103% (T103) of trochanter height (trochanteric method). The RF (resultant force), EF (effective force), and IE (index of effectiveness) were compared by measuring 3D motion and 3-axis pedal reaction force data during 4 pedaling phases (phase1: $330^{\circ}-30^{\circ}$, phase2: $30^{\circ}-150^{\circ}$, phase3: $150^{\circ}-210$, phase4: $210^{\circ}-330^{\circ}$). Results showed that there were significant differences in EF at phase1 between T97 and K25, in EF at phase4 between T100 and T103, in IE at total phase between T97 and K25, between T100 and T103, in IE at phase1 & phase2 between T97 and K25. There was higher IE in the K25 than any other saddle heights, which means that K25 was better pedaling effectiveness than the trochanteric method. Therefore it was suggested the saddle height as 103.7% of trochanter height that converted from K25.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.1165-1166
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.1139-1140
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• 2012

• 충청수학회지
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• 제29권1호
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• pp.23-28
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• 2016

In this paper, we obtain close characterizations of flows near a saddle set which is one of the interesting unstable closed sets. Also, we consider some conditions that closed sets are to be stable.

• 대한수학회보
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• 제54권3호
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• pp.715-729
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• 2017

In this paper, we investigate the existence and multiplicity of solutions for systems driven by two non-local integrodifferential operators with homogeneous Dirichlet boundary conditions. The main tools are the Saddle point theorem, Ekeland's variational principle and the Mountain pass theorem.

• 대한수학회논문집
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• 제28권3호
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• pp.597-602
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• 2013

In this paper, Mond-Weir type duality results for a uncertain multiobjective robust optimization problem are given under generalized invexity assumptions. Also, weak vector saddle-point theorems are obtained under convexity assumptions.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.104-112
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• 2013

This study investigates the structural analysis result with vibration and fatigue on 3 kinds of bicycle saddle models. When the static load applies on the upper plane of model, maximum stress becomes within the allowable stress in case of model 1. As the value of Stress or deformation becomes lower on the order of model types 1, 2 and 3, these models become more stabilized or safer at durability in this order. On the vibration analysis, model type 1 has the maximum stress or deformation more than 5 times by comparing with model type 1 or 2. Model type 1 becomes most excellent on vibration durability. As maximum displacement due to vibration happens in case of model type 3, it becomes unstabilized. But the stresses of model types 1, 2 and 3 become within the allowable stress and these models are considered to be safe. At the status of the severest fatigue load, model type 3 becomes safer than model type 1 or 2. This study result is applied with the design of safe bicycle saddle and it can be useful to improve the durability by predicting prevention against the deformation due to its vibration and fatigue.