• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1368-1372
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• 2003

PMMA which is used as the bone cement for vertebroplasty is able to be a supporter, as a fixing supporter role, for broken trabecular structure, caused by the compressed fracture of spine on aged osteoporosis. In this thesis, as experimenting apparent density of bone pieces, we have figured out support extent of Young's modulus as classifying the bone pieces injected PMMA and the others which are not. In case of low apparent density of PMMA in some bone, Young's modulus seems to be more supportable to bone. On the other hand, if apparent density of bones is normal, injection of PMMA is not very effective on improvement in Young's modulus of bone cement injection.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.494-504
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• 2008

Successful design, construction and maintenance of NATM tunnel demands prediction, control, stability estimation and monitoring of surface settlement, gradient and ground displacement with high accuracy. Back analysis using measured data and forward analysis have been and are indispensable tools to achieve this goal. Sakurai provided the hazard warning levels for assessing the stability of tunnels using the relation of critical strain and apparent Young's modulus. This paper performed the estimation of tunnel stability on construction. Firstly, the apparent Young's modulus concept and back analysis method is introduced for the assessment of tunnel safety during excavation a brief framework. Secondly, this paper deals with case study using "Apparent Young's modulus" and "Back analysis" for the purpose of estimating the stability of NATM tunnel in Korea. Finally, a general method that can be estimated the tunnel stability discussed by a flow chart.

• 대한의용생체공학회:의공학회지
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• 제22권5호
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• pp.419-424
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• 2001

골다공증의 조기 발견 및 치료예후에도 영향을 미치는 망상골 구조의 영률(Young's Modulus)은 그 대상이 사람이므로 일반적인 인장 및 압축시험으로 구해내기는 불가능한 실정이다. 본 연구에서는 망상골 구조가 지니고 있는 영률을 평가함에 있어서 구형압입시험을 통하여 망상골 구조의 영률을 구하고자 하였으며 이를 전산화단층촬영(CT)에서부터 얻을 수 있는 밀도와 실제 측정해서 얻은 밀도와의 관계를 정량화하고자 한다. 31세 남성의 좌우 원위 대퇴골을 해부학적 좌표를 고려하여 고정한 다음 GE9800 CT장비를 사용하여 Imm간격으로 단층촬영을 실시하였으며. 각 영상으로부터 CT수(HU)를 구하였다 Dliamond saw를 사용하여 좌우 대퇴골으로부터 72개의 8mm 정방형 시편들을 추출하였으며. 제작한 구형압입시험기를 사용하여 각 시편의 IS. AP. 그리고 ML방향으로의 압입시험과 압축시험을 각각 실시하였으며, 이후 시편의 실제 겉보기 밀도를 측정하였다. 그 결과 IS방향의 영률이 AP 및 ML방향보다 유의하게 크게 나타났으며, AP방향의 영률 역시 ML방향보다 유의하게 큰 영률을 나타냄을 통하여 망상골의 직교성을 알 수 있었다. CT수와 각 방향의 영률과의 관계에서도 선형적 관계보다는 멱관계로 보다 더 잘 설명되어짐을 알 수 있었는데 이는 이전의 연구자들과 동일한 결과임을 알 수 있었다

• 대한의용생체공학회:의공학회지
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• 제24권4호
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• pp.369-373
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• 2003

골다공증에 의한 척추체의 압박골절은 뼈의 파단성 질병중에서 가장 흔하게 나타나는 증상이다 최근에 척추압박골절에 대한 의학적 치료방법으로 각광받고 있는 척추성형술은 골강화제를 주입함으로써 척추체를 강화하고 변형을 보정하며. 환자의 고통을 줄여준다. 그러나 종전 연구에서는 골강화제가 주입된 후 척추체의 기계적 특성 강화에 대한 연구가 전무했으므로, 본 연구에서는 PMMA의 물성을 바탕으로 돼지와 사체로부터 시편을 얻어 겉보기 밀도에 대한 순수 망상골과 PMMA가 주입된 망상골의 영률을 측정하였다. 겉보기밀도에 따른 영률은 순수망상골의 경우 멱급수의 형태를 가지며. PMMA가 주입된 망상골의 경우 선형적인 형태를 가졌다.

• 한국잠사곤충학회지
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• 제14권1호
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• pp.43-47
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• 1972

견층부위별견사의 기계적특성을 파악하고저 Deniroscope와on을 이용하여 실험한바 다음과 같은 결과를 얻었다. 1) 견층별견사의 건조 및 습윤절단강도는 견사섬도감소율에 비례하여 저하한다. 2) 내층견사의 습윤항장력은 외층견사에 대하여 37%로 나타났다. 3) 습윤처리에 의한 전견층의 절단강도(g/d) 31%, 감소하였다. 4) 대섬도당 견사의 건조 및 습윤절단강도는 내층견사가 제일 높았다. 5) Apparent young's modulus는 내층견사에서 증가하였다. 6) 습윤견사의 절단신도는 건조견사에 비해 15% 증가하였다.

• Geomechanics and Engineering
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• 제22권4호
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• pp.277-290
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• 2020

This paper presents an elastic-plastic solution for the circular tunnel of elastic-strain softening behavior considering the pressure-dependent Young's modulus and the nonlinear dilatancy. The proposed solution is verified by the results of the field measuring and numerical simulation from a practical project, and a published closed-form analysis solution. The influence of each factor is discussed in detail, and the ability of Young's modulus and dilatancy characterizing the mechanical response of surrounding rock is investigated. It is found that, in low levels of support pressure, adopting the constant Young's modulus model will seriously misestimate the surrounding rock deformation. Using the constant dilatancy model will underestimate the surrounding rock deformation. When adopting the constant dilatancy model, as the dilation angle increases, the range of the plastic region increases, and the surrounding rock deformation weakens. When adopting the nonlinear dilatancy, the plastic region range and the surrounding rock deformation are the largest. The surrounding rock deformation using pressure-dependent Young's modulus model is between those resulted from two constant Young's modulus models. The constant α of pressuredependent Young's modulus model is the main factor affecting the tunnel displacement. The influence of α using a constant dilatancy model is much more apparent than that using a nonlinear dilatancy model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1336-1340
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• 2003

The compressed fracture of spine caused by osteoporosis is one of the most frequent diseases in bone fracture. Recently the vertebroplasty has drawn much attention as a medical treatment for the compressed fracture of spine, which strengthens the vertebral body and corrects deformity, and relieves pain in patients by injecting bone cement. The purpose of this research is to provide the theoretical background for the vertebroplasty by employing scientific methods and thus to find out the improvements of the conventional surgical method. By applying the engineering analysis tools to clinical study, new application fields can also be obtained

• Journal of the Korean Wood Science and Technology
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• 제43권2호
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• pp.177-185
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• 2015

The goal of this study is to evaluate the limitation of ASTM D 198 bending and ASTM D 3044 in determination of elastic modulus and shear modulus. Different material properties and span to depth ratios were used to analyze the effects of material property and testing conditions. The ratio of true elastic modulus to apparent elastic modulus evaluated from ASTM D 198 bending sharply decreased with increment of span to depth ratio. Shear modulus evaluated from ASTM D 198 bending decreased with increment of depth, whereas shear modulus evaluated from ASTM D 3044 was hardly influenced by increment of depth. Poisson's ratio influenced shear modulus from ASTM D 198 bending but did not influence shear modulus from ASTM D 3044. Different shearing factor was obtained for different depths of beams to correct shear modulus obtained from ASTM D 198 bending equivalent to shear modulus from theory of elasticity. Equivalent shear modulus of materials could be obtained by applying different shearing factors associated with beam depth for ASTM D 198 bending and correction factor for ASTM D 3044.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.170-180
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• 2008

Successful design, construction and maintenance of NATM tunnel demands prediction, control, stability guidelines, the estimation pre-improvement support system and monitoring of surface settlement, gradient and ground displacement with high accuracy. Moreover, urban NATM tunnel under difficult geotechnical conditions is important the estimation and necessary of pre-improvement support system. Various strategies have been proposed for the quantitative estimation of pre-improvement support system. This paper was investigated and analysed an assessment technique for the quantitative estimation of pre-improvement support system on underground space, as mountain and urban tunnel, in detail. The analysis performed on design and construction stage with field database using the proposed stability estimation index by many researcher including the critical strain and the apparent Young's modulus concept.

• 대한기계학회논문집A
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• 제26권2호
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• pp.349-356
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• 2002

For two kinds of 25Cr-20Ni stainless steels, STS310J1TB and STS310S with and without a small amount of Nb and N, creep behavior has been studied in a stress and temperature range from 147 to 392 MPa and from 923 to 773 K with a special reference to tertiary creep. The average creep life of STS310J1TB was about 100 times longer than that of the STS310S. The apparent activation energy for the initial creep rate was 330 kJ/mol in STS310J1TB, while that of the STS310S was 274kJ/mol in a power law creep region and 478 kJ/mol in a region of power law breakdown (PLB). The activation energy for STS310S below PLB is close to the for self-diffusion. When compensating for the temperature dependence of the Young's modulus and the omega value, it was found that the apparent activation energy for STS310J1TB was reduced to the activation energy for diffusion of chromium atom in gamma steel. The stress exponent of STS310S was about 12.3 above PLB and 5.1 in a power law creep region. Notwithstanding that the creep condition for STS310J1TB was in a power law creep region, its stress exponent was 7.9 larger than that of STS310S corresponding to the same creep conditions. This was ascribed to the presence of fine precipitates in STS310J1TB.