• 대한의용생체공학회:의공학회지
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• 제29권2호
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• pp.151-158
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• 2008

To evaluate aortic wall stiffness without influence of different background blood pressure, a new technique was developed and verified. At eight swine descending aortae, volume-pressure measurement was performed using custom-made system. Based on averaged pressure-volume curve, aortic distensibility index was formulated to evaluate aortic wall stiffness regardless of variable blood pressure and aortic size. The variability of aortic distensibility index by pressure change was compared with other parameters for wall stiffness evaluation. Subsequently, the aortic distensibility index was calculated at 100 contrast-enhanced EBCT data sets of normal volunteers in regular health screening program. The measured aortic distensibility index was compared with age, coronary calcium score, and aortic calcium score. Between 50 and 360 mmHg of blood pressure, the coefficient of variance of aortic distensibility index was 22.00% as comparing with 88.99% of classical compliance. Based on age, aortic distensibility index showed correlation coefficient of 0.55, whereas classical compliance showed 0.26. The correlation coefficient with modified aortic calcification was 0.43. Linear regression study revealed statistical significance of correlation coefficients. The aortic distensibility index, the method to evaluate aortic wall stiffness free from variable blood pressure and aortic size, was developed and verified with significant practical feasibility.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.671-675
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• 2001

Elastomers, which are engine mounts and body mounting rubbers, are traditionally designed for NVH use in vehicles, and they are designed to isolate specific unwanted frequencies. According to the measurement of the characteristics of engine mounts and body mounting rubbers, dynamic stiffness changes with respect to the driving miles accumulated in engine mounts and initial load in body mounting. This study looks at the variability in same engine mount properties, and the desired dynamic stiffness may increased with driving miles accumulated. And the dynamic stiffness of body mounting rubber changes very stiff above 150Hz.

• 대한정형도수물리치료학회지
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• 제18권2호
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• pp.49-55
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• 2012

Background: The purposes of this study were to: 1) investigate the relation between thoracic kyphosis, postural stiffness and thoracic rotation and 2) the intra-rater reliability of the measurement methods for thoracic kyphosis and rotation angle. Methods: Thirty-nine young adults (13 males, 26 females) participated in the study. Thoracic kyphosis was measured using a Flexicurve while standing in their usual relaxed posture and then in their maximally erector posture. Index of kyphosis (IK) measures taken in the relaxed and maximally erect positions were used to estimate postural stiffness. Thoracic rotation range of motion (ROM) was measured using universal goniometer and inclinometer in two positions. The association between the magnitude of the IK and thoracic stiffness and thoracic rotation ROM was also examined. Reliability was determined using intra-class correlation coefficients (ICC). Results: When measured from the mean relaxed IK (${\pm}SD$) was 7.42 (${\pm}1.47$) and mean erect IK was 4.92 (${\pm}1.63$) and mean IK ratio was 1.66 (${\pm}.65$). The relaxed IK was significantly correlated with the range of motion thoracic rotation in two positions (r=.503~580, p<.01). Conclusion: Thoracic kyphosis in relaxed position was associated with the range of motion thoracic rotation. Thoracic kyphosis measurement with the Flexicurve and range of motion 2 techniques of thoracic rotation showed good reliablity and may be a useful measurement tool in clinical practice.

• 한국추진공학회지
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• 제20권5호
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• pp.31-39
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• 2016

본 논문은 볼트 체결 강성이 추력 시험대에 미치는 영향을 연구한 것이다. 추력 시험대는 추진기관의 추력 성능을 평가하는 장비로 추력, 피치력, 요력(3 분력) 작용선에 대응하는 3 분력 계측선간의 평행도와 3 분력 계측선의 상호 직각도가 다분력 추력시험대의 성능을 좌우한다. 따라서 시험대의 초기 형상을 작동 상태에서 유지시키는 것이 추력 시험대의 핵심 기능이다. 본 논문에서는 추력 시험대의 볼트 체결과 로드셀 트레인의 나사 체결의 공차 정확도가 추력 시험대에 미치는 현상을 규명하고 이를 극복하는 방안을 제시하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.641-646
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• 2009

Concrete tracks are superior to ballast tracks in the aspect of durability, maintenance and safety. However, deteriorated stiffness of railroad bed and settlement of soft ground induced by trapped or seepage water lead to problems in safety of train operation. In this research, characteristic stiffness of concrete tracks, which is determined from FRACTAL (Flexural-Rigidity Assessment of Concrete Tracks by Antisymmetric Lamb Waves) technique, was employed as an index of track displacement. The characteristic stiffness is defined using Poisson's ratio, moment of inertia and stiffness ratio of subgrade to slab. To verify validity and reliability of the proposed characteristic stiffness, experimental and theoretical researches were performed. Feasibility of the characteristic stiffness based on FRACTAL technique was proved at a real concrete track for Korean high-speed trains. Validity of the FRACTAL technique was also verified by comparing the results of impulse-response tests performed at the same measurement array and the results of SASW tests and DC resistivity survey performed at a shoulder nearby the track.

• 한국항공우주학회지
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• 제42권5호
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• pp.390-397
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• 2014

BO-105 헬리콥터는 무힌지 로터 허브시스템이 적용되었으며, 블레이드의 루트 영역이 무힌지 허브 시스템의 플렉셔에 해당한다. 따라서 본 블레이드를 이용한 훨타워 시험 수행을 대비하여 굽힘 강성이 낮은 플렉셔 부분에 대한 굽힘 강성 보강을 수행하였다. 플렉셔 굽힘 강성 보강 수행을 위해 플렉셔 부분의 단면 형상을 모델링하여 굽힘 강성을 계산하였으며, 이를 바탕으로 강성 보강을 위한 복합재의 두께를 선정하였다. 보강된 플렉셔의 실제 굽힘 강성을 확인하기 위하여 강성보강 전 형상에 대한 강성 측정 시험과 강성보강 이후 형상에 대한 강성 측정 시험을 수행하여 결과를 비교하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1992년도 토질동역학적 특성치의 결정법과 응용
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• pp.1-18
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• 1992

• 한국정밀공학회지
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• 제21권10호
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• pp.14-19
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• 2004

• 순환기질환의공학회:학술대회논문집
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• 순환기질환의공학회 2006년도 춘계학술강연회
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• pp.10-19
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• 2006

• 한국정밀공학회지
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• 제29권8호
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• pp.845-852
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• 2012

The diaphragm-type stylus probe was developed for ultra-precision on-machine measurement (OMM) application. This probe is equipped with two diaphragms which are parallel and one capacitive sensor is used for detecting the vertical motion of end tip in the stylus when it is contacted to the optical freeform surface. For better performance of proposed probes, several design parameters such as axial stiffness and the lateral deformations were investigated with finite element analysis techniques. To verify the feasibility, the profiles of the master sphere ball were measured on the ultra-precision milling machine. The measurement results show that the proposed probe can calculate the radius of the circle within the accuracy of 0.1 ${\mu}m$ for the ultraprecision optical surface.