Some aspects of load-rate sensitivity in visco-elastic microplane material model

Ivica Kožar,Joško Ožbolt 사단법인 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.4

The paper describes localization of deformation in a bar under tensile loading. The material of the bar is considered as non-linear viscous elastic and the bar consists of two symmetric halves. It is assumed that the model represents behavior of the quasi-brittle viscous material under uniaxial tension with different loading rates. Besides that, the bar could represent uniaxial stress-strain law on a single plane of a microplane material model. Non-linear material property is taken from the microplane material model and it is coupled with the viscous damper producing non-linear Maxwell material model. Mathematically, the problem is described with a system of two partial differential equations with a nonlinear algebraic constraint. In order to obtain solution, the system of differential algebraic equations is transformed into a system of three partial differential equations. System is subjected to loadings of different rate and it is shown that localization occurs only for high loading rates. Mathematically, in such a case two solutions are possible: one without the localization (unstable) and one with the localization (stable one). Furthermore, mass is added to the bar and in that case the problem is described with a system of four differential equations. It is demonstrated that for high enough loading rates, it is the added mass that dominates the response, in contrast to the viscous and elastic material parameters that dominated in the case without mass. This is demonstrated by several numerical examples.

Migration of Rod into Retroperitoneal Region: A Case Report and Review of the Literature

Yaşar Bayri,Murat Sakir Eksi,Ramazan Doğrul,Demet Yalçinkaya Koç,Deniz Konya 대한척추신경외과학회 2014 Neurospine Vol.11 No.4

Spinal stabilization with fusion is the widely used method for traumatic or pathologic fracture of spine, spinal stenosis, and spondylolisthesis. Complications may emerge during or after the operations. Infection, hematoma and neurological deficits are early noticed findings. Screw and/or rod fractures present in long-term after surgery. Rod migration in out of the spinal column is a rare entity. A 67-year-old woman was visited our clinic for right leg pain. She had a previous spinal instrumentation surgery for spondylolisthesis in another center 6 years before. After radiological work-up, a distally migrated rod piece was observed in the retroperitoneal portion. The patient was operated for degenerative change; old instruments were replaced and extended to the L2 level with posterior spinal fusion. After the operation, her right leg pain improved. The asymptomatic migrated rod piece has regularly been followed clinically and radiologically, since then. Although it has rarely been reported, migration of the instrumentation material should be kept in mind. Spinal fixation without fusion makes the mechanical system vulnerable to motion effects of spine, especially in a degenerative and osteoporotic background. Long-term, even life-long follow-up is necessary for late term complications.

Anterior Segment Changes during Accommodation in Accommodative Esotropia

Mustafa Koç,Hakan Halit Yaşar,Mehmet Murat Uzel,Salih Çolak,Irfan Durukan,Pelin Yılmazbaş 대한안과학회 2018 Korean Journal of Ophthalmology Vol.32 No.1

To evaluate the anterior segment biometric parameters of non-accommodative and accommodativerefractive accommodative esotropia (RAE). Methods: Eighty-one eyes of 81 patients were included in this prospective, case-control study. The patientswere divided into three groups as follows: the RAE group (n = 31), the hypermetropia group (n = 25), and theemmetropia group (n = 25). Measurements were obtained in the non-accommodative (0.0 diopters) and accommodativestatus (-5.0 diopters) using a Pentacam HR. The anterior chamber depth (ACD), anterior chambervolume (ACV), pupil diameter (PD), and anterior chamber angle (ACA) were evaluated at all four quadrants. Results: The ACD, ACV and PD values in the RAE group were lower than those of the other groups in bothstates (p < 0.05). The ACD values were lower in the hypermetropia group than in the emmetropia group for thenon-accommodative status (p = 0.024) but were similar for the accommodative status (p = 0.225). PD and ACVvalues were lower in the hypermetropia group than in the emmetropia group in both states (non-accommodativestatus, p = 0.011 and p = 0.022; accommodative status, p = 0.026 and p = 0.034, respectively). Changes inACD, ACV and PD during accommodation (Δ) were not significant in the RAE group but were significant for theother groups (hypermetropia: ΔACD, p = 0.001; ΔACV, p = 0.001; ΔPD, p = 0.002; emmetropia: ΔACD, p < 0.001;ΔACV, p = 0.001; ΔPD, p < 0.001). These changes were significantly lower in the hypermetropia group than inthe emmetropia group (ΔACD, p = 0.012; ΔACV, p = 0.031; ΔPD, p = 0.034). Conclusions: The anterior chamber in RAE patients was shallower and the increase in convexity of the anteriorsurface or forward movement of the crystalline lens was more limited during accommodation in RAE.

Cytogenetic Finding of Breast Cancer Cases and in Their First-Degree Relatives

Dilek Aşcı Çelik,Nurten Özçelik,Erol Eroğlu,Pınar Aslan Koşar 한국유방암학회 2013 Journal of breast cancer Vol.16 No.3

Purpose: The aim of this study was to evaluate and compare the rate of sister chromatid exchange (SCE), the occurrence of micronuclei, and the lymphocyte proliferation rate index (PRI) in patients with breast cancer, their first-degree relatives, and healthy volunteers. Methods: We analyzed the frequency of SCE and micronuclei, and the PRI in the peripheral blood lymphocytes of 30 women with breast cancer, 22 of their female family members,and 20 age-matched healthy female volunteers. Results:SCE occurred significantly more often in the lymphocytes of breast cancer patients (10.84±0.4 per metaphase), compared with their first-degree relatives (7.45±0.54) and controls (5.94±0.2) (p<0.001 for both). The mean SCE frequency was not statistically different between first-degree relatives and controls (p=0.071). Similarly, micronuclei occurred at a significantly higher rate in breast cancer patients (9.6±0.72), and in their first-degree rela tives (7±0.64), compared to controls (3.85±0.4) (p<0.001 and p=0.001, respectively). There was also a significant difference between the occurrence of micronuclei in patients compared to their family members (p=0.021). The PRI was significantly lower in patients (1.61±0.1), compared with both their first-degree relatives (1.75±0.1), and controls (1.74±0.1) (p=0.001 and p=0.002,respectively). Conclusion: Increased SCE and the occurrence of micronuclei, as well as a reduced PRI are associated with breast cancer. Furthermore, increased SCE and the frequency of micronuclei in a first-degree relative suggest that they exhibit greater genetic instability than women of the same age.

Experimental and numerical investigations on spray structure under the effect of cavitation phenomenon in a microchannel

Morteza Ghorbani,Abdolali Khalili Sadaghiani,Mehmet Yidiz,Ali Koşar 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.1

In this study, the effect of upstream pressure on cavitation flows inside a microchannel with an inner diameter of 152 µm and resulting spray structure were experimentally and numerically investigated. The effects of bubble number density on two-phase flow hydrodynamics were studied using the numerical approach, where transient model was utilized to obtain the changes in vapor quality inside the microchannel and velocity field near the inlet and outlet of the nozzle. Spray visualization was carried out at a distance of 4.5 mm from the tip of the microchannel using the high speed visualization system. The experimental results showed that the spray cone angle increased with upstream pressure, and beyond the upstream pressure of 50 bar, the liquid jet flow changed to the cloudy spray flow. The bubble collapse was recorded at upstream pressures of 100 and 120 bar, where the cavitation bubbles extended to the outlet of the microchannel, and their collapse took place around the spray.

Consumer Satisfaction and Event Quality Perception: A Case of the 2009 World Professional Taekwondo Tour

( Yong Jae Ko ),( Kevin P Cattani ),( Su Ar Lee ),( Tae Ho Kim ),( Jin Bang Yang ),( Yong Bom Kim ) 국제태권도학회 2014 Journal of the International Association for Taekw Vol.1 No.1

Today, numerous martial arts events are held around the world. However, scholarly efforts have not been made to understand the spectator profile in martial arts events. The purpose of this study was twofold: (a) to identify perceived event quality factors that influence spectators` satisfaction and revisit intention, and (b) to examine event quality perceptions, satisfaction, and revisit intentions through the lens of spectator gender. Regression analyses and ANOVAs were employed to analyze the survey data collected from spectators who attended the 2009 World Professional Taekwondo Tour. Game performance, entertainment, and socialization opportunity were found to be important variables for spectator revisit intention. The results also showed that event quality perceptions varied depending on the gender of spectators. Marketers can develop effective event operation management and market strategies and stay relevant in a competitive market environment. The issue of event quality in special events such as martial arts events has not received scholarly attention. As such, the results of the current study will contribute not only to the event management literature but also to the further growth of the martial arts industry.

Assessment of genetic diversity among Korean sorghum (Sorghum bicolor (L.) Moench) resources using SSR markers

JY Park,AR Kim,SY Yoo,JI Kim,TW Jung,SH Woo,HY Heo,TW Kim,TS Ko 한국육종학회 2013 한국육종학회 심포지엄 Vol.2013 No.07

Grain sorghum is the fifth most important crop grown in the world for either a major food crop or animal feed. It is important to identify the genetic diversity of sorghum genetic resources for cultivar development and evaluation of sorghum accessions in Korea. Two hundred thirty six SSR primer sets, which are evely distributed across the sorghum genome, were used to assess the genetic variation of 23 sorghum accessions with a US cultivar, BTx623. Results showed that SSR markers were highly polymorphic among the sorghum collections and the average alleles per locus were 3.15 with the average of 0.436 PIC (polymorphism information content) values. The sorghum accessions in this study were unequally separated and were clustered into 4 groups. The results showed that there was a sufficient SSR polymorphism with SSR primers used among Korean sorghum accessions, and the development of genetic map and marker-assisted selection for cultivated sorghum would be feasible with further studies.

Study on the polymorphism between brown midrib mutants and Hwangkeumchal using SSR markers toward sorghum QTL mapping on excessive water stress

JY Park,AR Kim,SY Yoo,JI Kim,TW Jung,SH Woo,HY Heo,TW Kim,TS Ko 한국육종학회 2013 한국육종학회 심포지엄 Vol.2013 No.07

Excessive water stress can cause severe damage to sorghum and results in significant yield reduction. The aim of this study is to identify quantitative trait loci (QTL) for excessive water stress in sorghum. As a first step, two out of 21 bmr mutants were selected for their superior agronomic performance and Chlorophyll a fluorescence OJIP transient, and were crossed with an elite Korean cultivar, Hwangkeumchal, to construct mapping populations. One hundred ten out of 236 SSR primers showed polymorphism between two parens, which cover ten chromosomes of sorghum from different published SSR linkage maps of sorghum. Development of recombinant inbred lines from the crosses ‘25M2-0698 x Hwangkeumchal’ and ‘25M2-0404 x Hwangkeumchal’ are in progress using the single seed descendent method for generation acceleration.

Premedication Methods in Nasal Endoscopy: A Prospective, Randomized, Double-Blind Study

Mehmet İlhan Şahin,Kerem Kökoğlu,Şafak Güleç,İbrahim Ketenci,Yaşar Ünlü 대한이비인후과학회 2017 Clinical and Experimental Otorhinolaryngology Vol.10 No.2

Objectives. To identify the optimal pharmacological method of preparing patients for nasal endoscopy. Methods. Twenty healthy volunteers were enrolled in this prospective, randomized, double-blind study. Four types of medications were applied in their nostrils with binary combinations of spray bottles on four different days in a random order: placebo (normal saline [NS]+NS), decongestant (NS+oxymetazoline), anesthetic (NS+lidocaine), and decongestant plus anesthetic (oxymetazoline+lidocaine). Rigid nasal endoscopy was performed 10 minutes after spray application. The volunteers evaluated the discomfort caused by each spray application, and nasal pain scores due to the passage of the endoscope. The physicians quantified nasal decongestion using a visual analogue scale. Endoscopy duration as well as pulse and mean blood pressure (MBP) before spray application, 10 minutes after the application, and immediately after endoscopic examination were also recorded. Results. The discomfort caused by lidocaine was significantly higher than that caused by the other sprays (P<0.001). The lowest pain score related to endoscopy was obtained for oxymetazoline+lidocaine (P<0.001). Nasal decongestion was best achieved with NS+oxymetazoline (P<0.001). Endoscopy duration was the shortest for oxymetazoline+lidocaine (P<0.05). Statistically significant MBP changes were only seen with the application of NS+oxymetazoline (P<0.05). However, neither MBP nor pulse rate change was significant clinically. Conclusion. Application of decongestant and anesthetic sprays together seems to be the best method of pharmacological preparation of patients for nasal endoscopy.

Proteomic analysis of muscarinic acetylcholine receptor-mediated proliferation in HT-29 human colon cancer cells

Lee, Soo Youn,Lee, Ar-Reum,Ahn, Ji-Young,Ko, Jung Ho,Lee, Lyon,Han, Janet,Kim, Young-Chang,Kim, Yang-Hoon THE KOREAN SOCIETY OF TOXICOGENOMICS AND TOXICOPRP 2018 MOLECULAR AND CELLULAR TOXICOLOGY Vol. No.

Backgrounds: Muscarinic acetylcholine receptors (mAChRs) are members of G-protein-coupled receptors. They can induce agonist-dependent neoplastic transformation and facilitate colon cancer proliferation via promoting rapid expression of a variety of early responsive genes. Methods: In this study, we used 2-dimensional gel electrophoresis(2-DE) approach with subsequent mass spectrometry (MS) to identify up- and down-regulated proteins (a total of 23 protein spots) involved in mAChRs-related signaling pathway, energy metabolism, transcription/translation, oxidative stress metabolism and cytoskeleton organization in agonist carbachol stimulated HT-29 human colon cells. Results: We found that the increased expression of adenocarcinoma biomarker, annexin A5 (ANXA5) induced by carbachol treatment, which was confirmed by immunoblot. This study contributes to the understanding of mechanisms underlying mAChRs agonist-induced expression of whole proteins in HT-29 colon cancer cells. Conclusion: Our results indicated that ANXA5 might serve as a potential biomarker for the diagnosis of colon cancer.