Strains around distally inclined implants retaining mandibular overdentures with Locator attachments: an in vitro study

Moustafa Abdou Elsyad,Fathi Abo Setta,Ahmed Samir Khirallah 대한치과보철학회 2016 The Journal of Advanced Prosthodontics Vol.8 No.2

PURPOSE The aim of the present study was to evaluate, by means of strain gauge analysis, the effect of different implant angulations on strains around two implants retaining mandibular overdenture with Locator attachments. MATERIALS AND METHODS Four duplicate mandibular acrylic models were constructed. Two implants were inserted in the canine regions using the following degrees of distal inclinations: group I (control); 0°, group II; 10°, group III; 20°, and group IV; 30°. Locator pink attachments were used to connect the overdenture to the implants and Locator red (designed for severely angled implants) was used for group IV (group IVred). For each group, two linear strain gauges were attached at the mesial and distal surfaces of the acrylic resin around each implant. Peri-implant strain was measured on loading and non-loading sides during bilateral and unilateral loading. RESULTS For all groups, the mesial surfaces of the implants at loading and non-loading sides experienced compressive (negative) strains, while the distal implant surfaces showed tensile (positive) strains. Group IV showed the highest strain, followed by group III, group II. Both group I and group IVred showed the lowest strain. The strain gauges at the mesial surface of the loading side recorded the highest strain, and the distal surface at non-loading side showed the lowest strain. Unilateral loading recorded significantly higher strain than bilateral loading. CONCLUSION Peri-implant strains around two implants used to retain mandibular overdentures with Locator attachments increase as distal implant inclination increases, except when red nylon inserts were used.

Strain Hardening Behavior During Manufacturing of Tube Shapes by Hydroforming

박현규,이혜경,Chester J. Van Tyne,문영훈 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.6

Safe and robust process design relies on knowledge of the evolution of the mechanical properties in a tube during hydroforming. The manufacturing of tubular shapes generally consists of three main stages: bending, preforming, and expansion. The latter is usually called hydroforming. As a result of these three steps, the final product’s strain hardening history is nonlinear. In the present study, the strain hardening behavior during hydroforming was experimentally investigated. The variation of local flow stress and/or local hardness was used as an index of the strain hardening during the various steps and the local flow stress and/or local hardness were used with respective correlations to determine the effective strain. The strain hardening behavior during hydroforming after preforming has been successfully analyzed by using the relationships between hardness, flow stress, and effective strain for variable pre-strains prior to hydroforming. The comparison of predicted hardness with measured hardness confirms that the methodology used in this study is feasible, and that the strain hardening behavior can be quantitatively estimated with good accuracy. Safe and robust process design relies on knowledge of the evolution of the mechanical properties in a tube during hydroforming. The manufacturing of tubular shapes generally consists of three main stages: bending, preforming, and expansion. The latter is usually called hydroforming. As a result of these three steps, the final product’s strain hardening history is nonlinear. In the present study, the strain hardening behavior during hydroforming was experimentally investigated. The variation of local flow stress and/or local hardness was used as an index of the strain hardening during the various steps and the local flow stress and/or local hardness were used with respective correlations to determine the effective strain. The strain hardening behavior during hydroforming after preforming has been successfully analyzed by using the relationships between hardness, flow stress, and effective strain for variable pre-strains prior to hydroforming. The comparison of predicted hardness with measured hardness confirms that the methodology used in this study is feasible, and that the strain hardening behavior can be quantitatively estimated with good accuracy.

Strain-Rate Effect on the Stress and Strain Concentration in a Visco-Plastic Plate With An Elliptic Hole

Yanqiu Chen,Jin Zhang,Peishi Yu,Jian Wu,Weibo Wang,Junhua Zhao 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.4

The stress and strain concentration in some component has been a signifi cant topic for structural safety assessment. However, the evaluation of the stress and strain concentration based on the widely existing solutions for linear elastic material under static loading would lead to remarkable errors when the material undergoes the dynamic loading, since the coupling eff ect induced by the nonlinearity of the stress–strain relationship and the strain-rate strengthening could be of signifi cant infl uence. Here we analyzed the strain-rate dependent concentration of stress and strain for a visco-plastic plate with an elliptic hole subjected to dynamic loading. The three-dimensional stress and strain are calculated by fi nite element analyses based on a rate-dependent Johnson–Cook model in which the material constants are set according to a typical visco-plastic standard 45 carbon steel. Our results show that both the plastic stress and strain concentration factors signifi cantly depend on not only the strain but also the strain rate. With the increment of the remote strain rate, the stress concentration monotonically increases, while the strain concentration shows decreasing tendency.

Karasek의 Job Content Questionnaire와Korea Occupational Stress Scale의 비교 연구

이종빈 ( Jong Bin Lee ),장성록 ( Seong Rok Chang ) 한국안전학회(구 한국산업안전학회) 2015 한국안전학회지 Vol.30 No.1

According to the report of the WHO, workers have been exposed to much job strain such as job load, responsibility, role, interpersonal conflict etc. In Korea, studies on job strain started to become active from 1990s and now hundreds of studies are actively undergoing or publishing so that the studies are contributing to development and improvement of job strain. Representative measurement models of job strain are Job Strain Model of Karasek, Job Stress Model of NOISH, Korea Occupational Stress Scale, JSQ(Job Stress Questionnaire), K-OSI(Korea Version of Occupational Stress Inventory) etc. (Lee Kwan-Suk, 2012 ; KOSHA, 2003). Among them, Job Strain Model of Karasek had been loved by many researchers of job strain before Korea Occupational Stress Scale was developed. Job Strain Model of Karasek had been fitted to Korean style and then, used to analyze job strain of Korean people so that this Scale highly contributed to seeking relationship with cardiovascular disease, musculoskeletal disease caused by job, smoking, drug, alcohol poisoning, and pulse(Lee Kwan-Suk, 2012). But as this Model was studied and developed based on foreign culture and life pattern, amodel fit to Korea was developed to measure job strain for Korean people, which is Korea Occupational Stress Scale now most frequently used in measuring job strain. Accordingly, after this study made questionnaire survey about same population using the two me thods used most frequently in measuring job strain, the study investigated what features appeared, what correlations appear between two models, and comparatively analyzed characteristics each independent and dependent variable. Based on this, the study aimed to exactly express job strain of Korean people. The subjects of the study were a population of 233, and Karasek`s Questionnaire and KOSS`s Questionnaire were surveyed at the same time. The results were analyzed by statistical program to obtain significant difference between two models. Four particular groups were divided with Job Strain Model of Karasek and the four particular groups were measured with Korea Occupational Stress Scale. And job strain come from combination of two models was measured, with which new comparative analysis method was suggested

Evaluation of the KOGENE Real-time PCR Kit for Identification on Beijing Strain of Mycobacterium Tuberculosis and Its Application on Clinical Isolates from the National Tuberculosis Hospital

( Taeuk Kang ),( Yoohyun Hwang ),( Jiyeon Kim ),( Jihee Jung ),( Dagyum Lee ),( Sungweon Ryoo ) 대한결핵 및 호흡기학회 2021 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.129 No.-

Purpose Tuberculosis (TB) remains as public health burden in Korea. Beijing strain of Mycobacterium tuberculosis (M. tuberculosis) is assumed to be associated with hypervirulence and multi-drug resistance hence detection of such strain helps rapid detection of drug resistance. Thus, identification of Beijing strain is highly significant, in epidemiological and clinical aspects. Here, we present evaluation of the Real-time PCR kit for Beijing strain of Mycobacterium tuberculosis diagnostic® (KOGENE, Korea) (KOGENE RT-PCR) Method The 200 DNA samples, where 100 were clinical M. tuberculosis from Masan National Tuberculosis Hospital and other 100 were non-M. tuberculosis, were used. Strains of 100 M. tuberculosis were identified using MIRU-VNTR typing kit® (GenoScreen, France) and MIRU-VNTRplus database (URL: https://www.miru-vntrplus.org/MIRU/index.faces). Based on MIRU-VNTR result, the 84 out of 100 samples are identified as Beijing strain and remaining 16 samples are identified as non-Beijing strains. The KOGENE RT-PCR was conducted according to the manufacturer’s manual. Amplification of VIC fluorescence indicates M. tuberculosis-positive and amplification of both VIC and FAM fluorescences indicates Beijing strain of M. tuberculosis-positive. Result Of 200 samples, only 100 M. tuberculosis samples were amplified for VIC, showing 100% for both sensitivity and specificity with 95% Confidence of Interval (CI) value of 96.38-100%. Out of 100 M. tuberculosis, 84 Beijing strain of M. tuberculosis were positive for FAM, indicating 100% for both sensitivity and specificity with 95% CI values of 95.70-100% and 96.87-100% respectively (Table 1). Conclusion The clinical implication of Beijing strain is widely known. Here, investigated RT-PCR has shown capability in Beijing strain identification. Application of this tool could contribute in M. tuberculosis identification and prediction of possible drug resistance during pre- and initial treatment. Also, several outbreaks have been occurred by M. tuberculosis with Beijing strain. Hence, early identification of such strain is considered as highly useful in epidemiological TB investigation.

Lateral strain-axial strain model for concrete columns confined by lateral reinforcement under axial compression

Chongchi Hou,Wenzhong Zheng 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.2

The use of lateral reinforcement in confined concrete columns can improve bearing capacity and deformability. The lateral responses of lateral reinforcement significantly influence the effective confining pressure on core concrete. However, lateral strain-axial strain model of concrete columns confined by lateral reinforcement has not received enough attention. In this paper, based on experimental results of 85 concrete columns confined by lateral reinforcement under axial compression, the effect of unconfined concrete compressive strength, volumetric ratio, lateral reinforcement yield strength, and confinement type on lateral strain-axial strain curves was investigated. Through parameter analysis, it indicated that with the same level of axial strain, the lateral strain slightly increased with the increase in the unconfined concrete compressive strength, but decreased with the increase in volumetric ratio significantly. The lateral reinforcement yield strength had slight influence on lateral strain-axial strain curves. At the same level of lateral strain, the axial strain of specimen with spiral was larger than that of specimen with stirrup. Furthermore, a lateral strain-axial strain model for concrete columns confined by lateral reinforcement under axial compression was proposed by introducing the effects of unconfined concrete compressive strength, volumetric ratio, confinement type and effective confining pressure, which showed good agreement with the experimental results.

동맥 전단부에 분포된 원주 변형율에 대한 잔유 변형율의 영향

황민철,신정욱 대한의용생체공학회 1995 의공학회지 Vol.16 No.3

The distribution of circumferential strain of arterial cross-section Is highest at intima and lowest at adventitia. However, the circumferential strain is theoretically severe at Intima because there is strain concentration. The theoretical degree of the intimal strain can not be explained in physiological condition even though artery is physiologically normal. Physiological adaptation may be undertaken to strain concentration. However, it is not clear, yet. Residual strain of artery is eagerly studied. There is experimental evidence that residual strain exists in artery. When ring of artery is longitudinally cut, it is opened. Assumption is made that intimal strain concentration is reduced with the considel'ation of residual strain. This study experimentally attempts to quantify the effect of residual strain on circumferential strain which is determined under the assumption of zero strain with zero pressure. 혈압에 의한 안쪽벽의 변형을 집중현상으로 인한 동백 전단부의 변형율 gradient의 심각성은 잔유 변형율에 의해 감소되거나 없을 수 있다는 가정을 실험적으로 시도했다. 잔유변형율과 압력에 의한 변형율을 측정하여 잔유변형율이 원주변형율에 끼치는 영향을 알아 보았다. 결과로서 변형율 gradient를 줄이거나 없을수도 있으나 negative gardient가 평균적으로 나타났다. 즉 전체변형율(원주변형율+잔유변형율)은 안쪽벽이 낮고 바깥쪽이 높은 것으로 나타났다.

초파리의 Hybrid Dysgenesis에 관한 연구 : Ⅶ. Q Strain의 Cytotype Conversion

추종길,김선미 中央大學校 遺傳工學硏究所 1994 遺傳工學硏究論集 Vol.7 No.1

1992년 안양에서 채집한 초파리(Dosophila melanogaster)의 P 전이인자에 대한 strain type을 판정하기 위하여 난소 불임실험을 수행하였다. 안양집단의 P 인자의 활성과 세포질형을 비교, 분석한 결과 P인자의 활성은 전체 118개 iso-female line의 대부분이 10% 미만의 불임률을 나타내는 반면, 125개 iso-female line은 세포질형에 대한 불임률은 0-100%까지 고른 분포를 나타내어 높은 다형적 분포를 나타내었다. 안양 초파리 자연집단의 P 전이인자의 계통형 분석 결과 89 line중에 Q strain은 67.31%를 나타내었고 M' strain은 27 line으로 30.68%를 차지하고 있는 것으로 나타내어 Q strain이 우세하게 분포하고 있음을 알 수 있었다. Strain type이 판정되어 계대사육이 된 Q strain과 표준 M strain인 Canton-S를 재료로 하여 cytotype의 변화를 관찰하기 위해 역교배를 실시하였다. 그 결과 잡종자손의 Gonadal strility값은 세대가 지남에 따라 크게 증가하였다. 이러한 결과로 미루어 보아 cytotype은 P element에 의해 조절되어지며 자연집단에서의 유지는 stochastic loss 가설에 의하여 보존되어지는 것으로 보여진다. In Drosophila melanogaster the interactions of the P-M system generate germline aberration (e.g., GD sterility), found in certain interstrain hybrid. The genetic regulation causing the reciprocal cross leads to the definition of two regulatory states in P and M strain. One of the two regulatory states is P cytotype, which represses the transposition of P element and M cytotype causes the transposition. We examined the Anyang natural population in order to determine the distribution of the P factor activity and the cytotype. Cytotype is one of the factors needed to cause hybrid dysgenesis. P factor activity was less than 30% in GD sterility in all of the 118 iso-female lines but the cytotype showed polymorphism by being measured to be various in GD sterility ranging from 0% to 100%. Strain type showed the Q strain was 67.31%(61/89 lines) whereas M' strain was 30.68(27/89 lines). This result means the Q strain was predominantly distributed in this population. The females of Q strains were backcrossed with Canton-S(M strain). Through the backcrossings, the change the cytotype was measured by gonadal dysgenesis. AS the cytotype changes, the ability of the female files to cause the gonadal sterility increased, the total amount of P element was possibly decreased. These results suggest that the cytotype was regulated by P element and seem to support the stochastic loss hypothesis.

Glacial and tidal strain of landfast sea ice in Terra Nova Bay, East Antarctica, observed by interferometric SAR techniques

Han, Hyangsun,Lee, Hoonyol Elsevier 2018 Remote sensing of environment Vol.209 No.-

<P><B>Abstract</B></P> <P>The dynamics of landfast sea ice, also called fast ice for short, has a large influence on the variability of polynyas and marine ecosystems, and the logistics for research stations near the Antarctic coast. Therefore, it is important to accurately measure the strain of fast ice and its seasonal variations, and to identify the cause of stresses on the ice. In this paper, we separate the strains from glacial stress and tidal stress of fast ice near the Campbell Glacier Tongue (CGT) in Terra Nova Bay, East Antarctica. This was done using observations from a series of one-day tandem COSMO-SkyMed Interferometric Synthetic Aperture Radar (InSAR) images obtained from December 2010 to January 2012. Firstly, we discriminated fast ice from pack ice and open water by analyzing the interferometric coherence values. We then identified the characteristics of the strains by investigating the equi-displacement lines of fringes in weekly InSAR and double-differential InSAR (DDInSAR) images. The weekly InSAR images predominantly showed glacial shear strain of the fast ice with fringes parallel to the sides of the CGT. This was due to the cumulative flow of the CGT for a week, while oscillating tidal signals were relatively small. The DDInSAR images, which cancelled glacial strain rates in two one-day InSAR images, showed a deformation of the fast ice by tidal sea surface tilt, with the fringes parallel to the coastline. Based on the unique characteristics of these strains, we separated them from the one-day InSAR images by decomposing the fringe patterns into glacial and tidal strain. Glacial shear strain rates of fast ice attached to the east of the CGT decreased from May to August owing to ice thickening and then stabilized until December. Those to the west of the CGT increased from May to July. This was possibly due to bottom melting of the ice by the increased ocean circulation during the expansion period of the nearby polynya. The glacial strain then decreased until December because of reduced polynya activity. The fast ice near the Jang Bogo Station (JBS) only showed tidal strain as it was isolated from the CGT by cracks and leads. Tidal strain rates of the fast ice were strongly correlated with the magnitude of tidal variations in all these regions, which represents shows that the tidal strain represents tidal sea surface tilt. The tidal response of fast ice to the west of the CGT and near the JBS was stronger than that to the east of the CGT, probably owing to thinner ice thickness there.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Glacial and tidal strain of fast ice near Campbell Glacier Tongue was investigated. </LI> <LI> Characteristics of the strains were identified from weekly InSAR and DDInSAR images. </LI> <LI> The strains were decomposed from one-day InSAR signals based on the characteristics. </LI> <LI> Glacial strain of fast ice varied seasonally due to the changes in ice thickness. </LI> <LI> Tidal strain representing tidal sea surface tilt was correlated with tide variations. </LI> </UL> </P>

대퇴 경부 골절에서의 stress와 strain에 관한 연구

이순혁,박상원,이홍건 고려대학교 의과대학 1990 고려대 의대 잡지 Vol.27 No.1

To study change of stress on the femoral neck after internal fixation of femoral neck fractures, comparison of strain on the fernoral neck between before and after femoral neck osteotomy was performed. The author used fourteen embalmed femora, two as control group and twelve as experimental group, which was further divided into two groups by difference of fixation method, and measured strains during loading along the weight-bearing axis with Instron. In two femora of the control group, five strain-gauges were bonded on five spots around the femoral neck and strains on five spots were measured. In twelve femora of the experimental group, two strain-gauges were bonded on selected two spots, each showed the highest amount of compressive or tensile strain according to experimental results of the control group among five spots, and strains were measured during loading. Then twelve femora in the experimental group, once loaded, were fixed with Knowles pins(six femora with three Knowles pins longitudinally and six femora with four Knowles pins quadriangularly) after femoral neck osteotomy and were loaded until internal fixation of femoral neck osteotomy failed(maximal loading force), while measuring strains on two spots of femoral neck. The ratio of strain on the same spot of the same femur between after and before femoral neck osteotomy was calculated. The author also observed the relationship between maximal loading force, difference of fixation method of Knowles pins and the ratio of strain between after and before femoral neck osteotomy. The results obtained are as follows : 1. In the femora of normal state, the tensile strain is higher on the antero-superior neck and the compressive strain on the poster on inferior neck of the femur. The strain on the mid-posterior neck was minimal. 2. In the twelve femora before femoral neck osteotomy, the ratio between the tensile strain on the antero-superior neck and the compressive strain on the postero-inferior neck in the same femur ranged from 29% to 92%, the mean value being 62±20.2%. 3. The ratio of the compressive strain on the cortex of the postero-inferior neck of the femur between after fixation of osteotomy and before osteotomy ranged from 47% to 210%, the mean value being 124±90.9% in six femora with three Knowles pins longitudinally and 128±70.6 % in the femora with four Knowles pins quadriangularly. 4. The ratio of the tensile strain on the cortex of the antero superior neck of seven femora, excluding five femora of disproportionally developed tensile strain, between after fixation of osteotomy and before osteotomy ranged from 25% to 80%. 5. The mean value of maximal loading force was 260±45.9Kp in six femora fixed with three Knowles pins longitudinally and 265±41.0Kp in six femora fixed with four Knowles pins quadriangularly. 6. The ratio of the compressive strain on the cortex of the posteroinferior neck of the femur between after fixation of osteotomy with and before osteotomy had close relationship with the maximal loading force. The maximal loading force had the mean value of 303±12.5Kp in six femora with the ratio less than 100%(47%70%) and the mean value of 221±16.9Kp in six femora with the ratio more than 100% (180%210%).