• 제목/요약/키워드: Flexibility Coefficient

검색결과 134건 처리시간 0.025초

유연체 로터-커플링-블레이드 시스템의 로터 축과 블레이드의 연성 진동에 관한 연구 (A Study on the Coupled Shaft-Torsional and Blade-Bending Vibrations in the Flexible Rotor-Coupling-Blade System)

  • 이선숙;오병영;윤형원;차석주;나성수
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 춘계학술대회논문집
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    • pp.221-226
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    • 2005
  • In this paper, a dynamic model for the rotor shaft-coupling-blade system is developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility is lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations is employed for developing the equation of the motion. The assumed modes method is used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearif, stiffness hardening and softening.

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견직물의 구조적 특성에 따른 질감이미지와 선호도 평가 (The Evaluation of Texture Image and Preference according to the Structural Characteristics of Silk Fabric)

  • 김희숙;나미희
    • 한국생활과학회지
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    • 제18권1호
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    • pp.137-143
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    • 2009
  • The purpose of this study is to examine the evaluation of texture image and preference according to the structural characteristics of silk fabric, and to analyze the effects of texture image and sensibility on the preference. 53 female subjects evaluated fabric image and sensibility of 17 specimens of white silk fabrics sold on the market with semantic differential scale. The data were analyzed through factor analysis, Pearson correlational coefficient and t-test using SPSS win 13.0. For the evaluation, structural characteristics such as fiber contents, weave type, weight and thickness were analyzed. Factor analysis showed that sensibilities were classified into 3 categories; 'surface property', 'weight', 'flexibility'. Fabric images were classified into 2 categories; 'elegance' and 'naturalness'. Statistically significant differences of structural characteristics on the texture image were observed. Weave type affected 'surface property' and fiber contents affected' flexibility'. Weight and weave type affected' elegance', too. The significant factors affecting preference were fabric image of 'elegance' and structural characteristics of 'weave type'. The results of this study showed that the most preferred silk fabric is smooth and soft satin weaved fabric with texture image of 'elegance'.

견직물의 물리적 자극에 따른 태와 역학적 특성 (Physical Stimulus of Silk Woven Fabrics, Subjective Hand and Mechanical Properties)

  • 김춘정;나영주
    • 한국의류학회지
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    • 제24권3호
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    • pp.429-439
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    • 2000
  • This study was aimed to investigate the handle and mechanical properties of silk woven fabrics according to the fabric structure and yarn types 56 male and female students evaluated 16 black specimens with semantic differential scale of 20 hand adjectives. Mechanical parameters such as surface properties, bending properties and compression properties were tested using by KES-FS system. Data were analyzed through factor analysis, pearson correlation coefficient and t-test using PC SAS package. The results were as follows: The hand adjectives were grouped as 4 'surface roughness', 'flexibility', ;sense of thermal', and 'dryness'. 'Surface roughness' was highly sensed at satin fabrics of hard-twist yarn, noil yarn and spun yarn, while it was not at the fabrics of normal satin and twill at all. 'Flexibility' was reverse to 'surface roughness'. Thermal sense was felt highly at satin fabrics of noil-yarn, while low at plain fabrics of normal yarn. 'Dryness' was high at satin fabrics of hard-twist yarn and while it was low at normal satin fabrics. Predicted equations for subjective hand from mechanical properties of fabrics were developed using Stevens's law and stepwise regression and the coefficients of determination were high.

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유연체 로터-커플링-블레이드 시스템의 로터 축과 블레이드의 연성 진동에 관한 연구 (A Study on the Coupled Shaft-torsional and Blade-bending Vibrations in the Flexible Rotor-coupling-blade System)

  • 오병영;이선숙;윤형원;차석주;나성수
    • 한국소음진동공학회논문집
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    • 제15권9호
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    • pp.1023-1029
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    • 2005
  • In this paper, a dynamic model for the rotor shaft-coupling-blade system was developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility was lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations was employed for developing the equation of the motion. The Assumed Modes Method was used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearity, stiffness hardening and softening.

간호학사 과정 3학년 학생들의 노인과 치매노인에 대한 태도 (Attitudes Toward General Elders and Elders with Dementia Among Baccalaureate Junior Nursing Students)

  • 김정희
    • 지역사회간호학회지
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    • 제18권4호
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    • pp.601-610
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    • 2007
  • Purpose: This study investigated attitudes toward general elders and elders with dementia among nursing students before beginning the clinical practicum. In addition, students' characteristics differentiating the attitudes were examined. Methods: Attitudes were measured with questionnaires developed for Asian culture at the beginning week of the first semester of the junior year in two baccalaureate programs. Responses from 120 out of 121 students were analyzed using Pearson correlation coefficient, paired t-test, ANOVA, and Scheffe test. Results: Students held negative attitudes toward both types of elders except for generosity dimension toward general elders showing a neutral attitude. Elders with dementia were evaluated more negatively than general elders in all the dimensions of vitality, generosity and flexibility. Vitality and generosity toward general elders were different according to intimacy and the degree of communication with elders. Generosity toward general elders was also different according to students' religious beliefs. Students with interest in elders/issues showed more negative attitudes of vitality and flexibility toward elders with dementia. Conclusions: Students in general had negative attitudes toward elders and more negative attitudes toward elders with dementia. We need to put more efforts into the entire nursing curriculum in order to improve attitudes toward elders with particular concern over attitudes toward elders with dementia.

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Intra-Rater Test-Retest Reliability of Ely's Test Using Smartphone in Patients With Lumbar Extension-Rotation Syndrome

  • Park, Kyue-Nam;Ha, Sung-Min;Chung, Sung-Dae;Kim, Si-Hyun;Jang, Jun-Hyeok
    • 한국전문물리치료학회지
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    • 제19권4호
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    • pp.46-54
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    • 2012
  • Ely's test is commonly used to assess rectus femoris muscle flexibility. however, a reliability limit of this test was demonstrated by a previous study. In this study, we present an alternative method using an application for a digital horizontal level in a smartphone (DHLS) to complement the reliability limit of Ely's test. The aim of this study was to examine the reliability of Ely's test using DHLS on the pelvis, compared to using visual observation (VO) of pelvic and hip motions. Nineteen patients with lumbar extension-rotation syndrome were recruited for this study. An examiner examined the rectus femoris flexibility (both pass/fail and goniometer scoring) through Ely's test using both DHLS and VO. A retest session was completed two hours later for within-day reliability and seven days later for between-day intra-rater test-retest reliability. Results showed higher Kappa values for pass/fail scoring and higher intraclass correlation coefficient values for goniometer scoring in Ely's test using DHLS, compared to using VO. Measurement error and Bland and Altman plots further demonstrated the degree of intra-rater variance during Ely's test using DHLS in a clinical setting, compared to using VO. These results demonstrated that Ely's test using DHLS showed acceptable reliability compared to using VO. Ely's test using DHLS could be widely used for measuring the rectus femoris muscle flexibility in patients with lumbar extension-rotation syndrome, although the inter-rater reliability needs to be established first.

Institutional Quality, Regulatory Environment and Microeconomic Performance: Evidence from Transition and Non-transition Developing Countries

  • Ochieng, Haggai Kennedy;Park, Bokyeong
    • East Asian Economic Review
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    • 제25권3호
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    • pp.273-309
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    • 2021
  • The development of regulatory systems varies between transition and non-transition economies. This suggests that they provide different incentives for entrepreneurial development and could have varied effects on the economy because they have different methods to deal with market failure. However, limited empirical evidence exists to prove the assumption of dichotomy. Using comprehensive data for institutional quality, labor market and financial market development, this research sought to analyze their effect on employment growth at micro level. The results show that the quality of institutions in transition economies are poorer relative to those in non-transition economies, but their financial and labor markets are more developed than the latter. Further analysis for the transition sample shows that the three variables are individually positively related with employment growth. For the non-transition sample, institutional quality and labor market flexibility bear a positive and significant effect on employment. Financial market development enters the model with a negative coefficient when regressed alone, but a joint test of significance finds that all the variables have a positive effect on employment growth. This result could imply that there is interdependence between institutional quality, labor flexibility and financial market development in firm-employment-growth relationship, or complementarity between regulations and the quality of institutions. Alternatively, this finding suggests that a stringently regulated credit market in non-transition economies have a selection effect-allocating credit only to entrepreneurs who already demonstrate strong growth potential. In sum, despite differences in the evolution of regulatory environment between the two samples, both of them complement employment growth at firm level. The overall implication of these findings is that less rigid regulations and coherent policies that are enforced with impartiality provide incentives for firms to expand.

침장용 PLA 섬유에 대한 저온 경화유제에 관한 연구 (Study on Low Temperature Curing Emulsion of PLA Fiber for Bedding)

  • 안영무
    • 패션비즈니스
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    • 제16권1호
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    • pp.41-51
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    • 2012
  • Polyester is mainly used as a bedding filler material. PLA fiber as an eco-friendly material for substituting polyester has a low melting temperature and therefore a hardening process is impossible. This study is to develop the oil for feather touch that can treat at the melting temperature of PLA. The slippery and soft aminosilicone emulsion, and the bulky epoxysilicone emulsion were used. They had proper viscosity and particle size for flexibility and elasticity. When using methoxy aminosilane [$H_2NSi(OCH_3)_3$] as an aminosilane and [$Zn(OCOCH_3)_2$] as a catalyst, the hardening reaction was fast and effective. Feather touch process were treated by 2 steps. At first step, aminosilicone emulsion, epoxysilicone emulsion and methylaminosilane were mixed and homogenized, and at second step, 5% blened solution of the first step, Zn catalyst 1%, distilled water 94% were treated at PLA fiber. After treatment the static friction coefficient and dynamic friction coefficient were reduced to 23.5-60.8% and 30.0-61.3% respectively, and the laundry and sun light fastnesses have not shown any decrease.

원전 EQS 면진장치의 성능개선을 위한 연구 (Study on the Performance Improvement of an EQS Device Applied Nuclear Power Plant)

  • 이유인;이유진;이홍표;조명석;지용수;백준호
    • 한국지진공학회논문집
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    • 제19권1호
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    • pp.13-19
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    • 2015
  • This paper presents the performance improvement of an EQS (Eradic Quake System) device applied to a nuclear power plant. For the nuclear facility, the EQS device needs to be ensured to have high quality, flexibility of design and reliability. To improve the reliability of the design, the hysteresis of the device must be exactly predicted. The friction coefficient of PTFE (PolyTetraFluoroEthylene) and the stiffness of the MER-Spring are considered as the factors influencing the hysteresis curve. In this paper, those factors are analysed to predict the behavior of the device and to improve the equipment of the EQS device. The results of the improved EQS device have been verified via a tests to be comparable with the predicted results. The estimation results indicate that considering those factors is more appropriate than the results of the previous design and method.

탄성지대를 갖는 사각형 평판의 자유진동해석 (Free Vibration Analysis of Rectangular Plate with Elastic Supports - Formulation by the Transfer Infiuence Coefficient Method -)

  • 문덕홍;여동준
    • 수산해양기술연구
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    • 제27권4호
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    • pp.313-320
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    • 1991
  • 본 연구에서는 전달영향계수법의 개념을 사각형 평판의 자유진동해석에 적용하여, 그 계산결과들을 전달매트릭스법 및 엄밀해 또는 Leissa 방법의 결과와 비교하여 그 유용성을 확인하였다. 전달영향계수법은 전달매트릭스법으로는 구하기 곤란한 고차의 고유진동수에 대해서도 정도좋게 구할 수 있으며, 계산속도의 면에서도 전달매트릭스법보다 우수함을 알 수 있었다. 또한, 전달영향계수법은 모든 경계조건 및 중간 경탄성 지지조건도 전단 및 회전 스프링정수 값의 조절만으로 간편하게 대응시킬수 있었다

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