• 제목/요약/키워드: CTT

검색결과 59건 처리시간 0.024초

Numerical simulation of tensile failure of concrete using Particle Flow Code (PFC)

  • Haeri, Hadi;Sarfarazi, Vahab
    • Computers and Concrete
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    • 제18권1호
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    • pp.39-51
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    • 2016
  • This paper considers the tensile strength of concrete samples in direct, CTT, modified tension, splitting and ring tests using both of the experimental tests and numerical simulation (particle flow code 2D). It determined that which one of indirect tensile strength is close to direct tensile strength. Initially calibration of PFC was undertaken with respect to the data obtained from Brazilian laboratory tests to ensure the conformity of the simulated numerical models response. Furthermore, validation of the simulated models in four introduced tests was also cross checked with the results from experimental tests. By using numerical testing, the failure process was visually observed and failure patterns were watched to be reasonable in accordance with experimental results. Discrete element simulations demonstrated that the macro fractures in models are caused by microscopic tensile breakages on large numbers of bonded discs. Tensile strength of concrete in direct test was less than other tests results. Tensile strength resulted from modified tension test was close to direct test results. So modified tension test can be a proper test for determination of tensile strength of concrete in absence of direct test. Other advantages shown by modified tension tests are: (1) sample preparation is easy and (2) the use of a simple conventional compression press controlled by displacement compared with complicate device in other tests.

Theoretical Study of Various Unit Models for Biomedical Application

  • Choi, Jeongho
    • 한국산업융합학회 논문집
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    • 제22권4호
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    • pp.387-394
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    • 2019
  • This paper presents an analytical study on the strength and stiffness of various types of truss structures. The applied models are triangular-like opened truss-wall triangular model (OTT), closed truss-wall triangular model (CTT), opened solid-wall triangular model (OST), and hypercube models defined as core-filled or core-spaced cube. The models are analyzed by numerical model analysis using DEFORM 2D/3D tool with AISI 304 stainless steel. Then, the ideal solutions for stiffness and strength are defined. Finally, the relative elastic modulus of the core-spaced model is obtained as 0.0009, which is correlated with the cancellous bone for the relative density range of 0.029-0.03, and the relative elastic modulus for the core-filled model is obtained as 0.0015, which is correlated with cancellous bone for the relative density range of 0.035-0.036. For the relative compressive yield strength, the OTT reasonably agrees with the cancellous bone for the relative density of 0.042 and the relative compressive strength of 0.05. The CTT and OST are in good agreement at the relative density of 0.013 and the relative compressive yield strength of 0.002. The hypercube models can be used for the cancellous bone for stiffness, and the triangular models can be used for the cancellous bone for strength. However, none of the models can be used to replace the compact bone because it requires much higher stiffness and strength. In the near future, compact bone replacement must be further studied. In addition, previously mentioned models should be developed further.

동시적 이중과제 훈련이 노인의 실행기능에 미치는 효과: 체계적 고찰 및 메타분석 (A Systematic Review and Meta-Analysis of the Effects of Simultaneous Dual-Task Training on Executive Function in Older Adults)

  • 전유진;박진혁
    • 재활치료과학
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    • 제10권3호
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    • pp.23-41
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    • 2021
  • 목적 : 본 연구는 노인을 대상으로 한 동시적 이중과제 훈련을 적용하였을 때 실행기능의 효과를 알아본 연구를 분석하는 것을 목적으로 한다. 연구방법 : PubMed, EMBASE, CoChrane, Web of Science, RISS를 이용하여 지난 10년간 출판된 논문을 검색하였고, 선정 및 배제 기준을 통해 최종 7편의 논문을 선정하였다. 선정 논문에 대한 PEDro 질적평가와 메타분석을 시행하였다. 결과 : 선정된 7편의 논문은 모두 무작위 대조군 설계로, PEDro Scale 7점 이상의 높은 편에 속하였다. 이중과제 훈련의 실행기능 효과를 보기 위한 평가도구로 4편의 문헌에서 선로잇기검사(Trail Making Test)를 사용하였고, 2편에서 색선로잇기검사(Color Trail Test)를 사용하였으며, 3편에서 스트룹검사(Stroop test)를 사용하였다. 메타분석을 실시한 결과 전체적인 실행기능의 향상은 0.38로 작은효과크기를 보였으며, 선로잇기검사와 색선로잇기검사는 0.37, 스트룹검사는 0.34로 작은효과크기를 보였다. 전체적인 실행기능 효과와 선로잇기검사, 색선로잇기검사의 효과크기만 통계학적으로 유의하였다(p<0.05). 결론 : 본 연구를 통해 이중과제 훈련이 노인의 실행기능 향상에 효과적임을 확인하였지만, 이중과제 훈련의 효과를 높이기 위해서는 훈련의 난이도 설정이 중요하며, 실행기능을 평가하는 다양한 평가도구와 실제 이중과제 조건에서의 수행도를 평가하는 평가도 동시에 이루어져야 함을 알 수 있었다. 이는 향후, 노인들의 실행기능 향상 훈련을 하는데 적절한 중재방법으로 사용될 수 있으며, 치매 발현을 늦추는데 도움이 될 것이라 사료된다.

H2O2 Generating Ability and Multi-Drug Resistance of Lactic Acid Bacteria Required for Long-Term Inpatient Treatment with Antibiotic Resistance

  • Yuk, Young Sam
    • International journal of advanced smart convergence
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    • 제11권4호
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    • pp.227-239
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    • 2022
  • Purpose: In our study, in order to find lactic acid bacteria (LAB) with multi-drug resistance to antibiotics, we isolated 140 strains from 15 types of kimchi commercially available in Korea and 20 types of Kimchi made at home from January to December in 2016, and investigated their H2O2 generating ability and multi-drug resistance to antibiotics. Methods: In order to observe the H2O2 generation ability of LAB, we performed the experiment with methods such as Rabe, Hillier, and Kang. To test the antibacterial susceptibility of LAB, we used the disc agar diffusion method using MRS agar (Difco, USA) according to the CLSI and WHO test methods. There are 18 types of antibiotic discs used. Results: Out of the total numbers of 140 strains, 6 strains of Ent. Faecium, 25 strains of L. plantarum, 1 strain of L. rhamnosus, 3 strains of L. sakei, 1 strain of L. acidophilus, 1 strains St. thermophilus, and 7 of unidentified strains generated H2O2. The antibiotic susceptibility of Ent. Faecium indicated SXT, OX, NA, and E; and the antibiotic susceptibility of L. plantarum indicated NA; and the antibiotic susceptibility of St. thermophilus indicated NA, CC, RA, CTT, CM, and P ; and the antibiotic susceptibility of L. rhamnosus indicated SXT, VA, NA and CTT; and the antibiotic susceptibility of 6 strains of L. sakei indicated SXT, OX, NOR, NA, CTT and CIP, all indicating antibiotic resistance. In the case of multi-drug resistance to antibiotics for 53 strains of L. antarum, 8-drug resistance was the most common with 25 strains, followed by 7-drug-resistant strains with 18 strains, 9-drug-resistant strains with 4 strains, 6-drug-resistant strains with 3 strains, 5-drug-resistant strains with 2 strains, and 17-drug-resistant strains with 1 strain. In the case of multi-drug resistance to antibiotics for Ent. Faecium 27 strains, 9-drug resistance was most commonly identified as 9 strains, 8-drug resistance was identified as 6 strains, 7- and 11 drug resistances were identified as 4 strains each, and 4- and 6-drug resistances were identified as 1 strain each. Conclusion: Ent. Faecium, L. plantarum, L. rhamnosus, L. sakei, and St. thermophilus, shown to have anantibacterial activity in previous studies on LAB and shown to have and H2O2 generating ability, antibiotic resistance and multi-drug resistance in this study, are expected to be able to play an excellent role for long-term inpatients to use as an alternative to antibiotics and to cope with emerging antibiotic resistance.

MODIS 위성 자료를 이용한 동아시아 에어로졸-구름의 통계적 특성 (Investigating Statistical Characteristics of Aerosol-Cloud Interactions over East Asia retrieved from MODIS Satellite Data)

  • 정운선;성현민;이동인;차주완;장기호;이철규
    • 한국환경과학회지
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    • 제29권11호
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    • pp.1065-1078
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    • 2020
  • The statistical characteristics of aerosol-cloud interactions over East Asia were investigated using Moderate Resolution Imaging Spectroradiometer satellite data. The long-term relationship between various aerosol and cloud parameters was estimated using correlation analysis, principle component analysis, and Aerosol Indirect Effect (AIE) estimation. In correlation analysis, Aerosol Optical Depth (AOD) was positively Correlated with Cloud Condensation Nuclei (CCN) and Cloud Fraction (CF), but negatively correlated with Cloud Top Temperature (CTT) and Cloud Top Pressure (CTP). Fine Mode Fraction (FMF) and CCN were positively correlated over the ocean because of sea spray. In principle component analysis, AOD and FMF were influenced by water vapor. In particular, AOD was positively influenced by CF, and negatively by CTT and CTP over the ocean. In AIE estimation, the AIE value in each cloud layer and type was mostly negative (Twomey effect) but sometimes positive (anti-Twomey effect). This is related to regional, environmental, seasonal, and meteorological effects. Rigorous and extensive studies on aerosol-cloud interactions over East Asia should be conducted via micro- and macro-scale investigations, to determine chemical characteristics using various meteorological instruments.

Efficacy and Safety of Combined Oral and Enema Therapy Using Polyethylene Glycol 3350-Electrolyte for Disimpaction in Pediatric Constipation

  • Yoo, Taeyeon;Bae, Sun Hwan
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • 제20권4호
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    • pp.244-251
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    • 2017
  • Purpose: We evaluated the efficacy and safety of combined oral and enema therapy using polyethylene glycol (PEG) 3350 with electrolyte solution for disimpaction in hospitalized children. Methods: We retrospectively studied 28 children having functional constipation who received inpatient treatment between 2008 and 2016. The amount of oral PEG 3350 electrolyte solution administered was 50-70 mL/kg/d (PEG 3350, 3-4.1 g/kg/d), and an enema solution was administered 1-2 times a day as a single dose of 15-25 mL/kg (PEG 3350, 0.975-1.625 g/kg/d). A colon transit time (CTT) test based on the Metcalf protocol was performed in some patients. Results: Administration of oral and enema doses of PEG 3350 electrolyte solution showed $2.1{\pm}0.3$ times and $2.9{\pm}0.4$ times, respectively. After disimpaction, the frequency of defecation increased from $2.2{\pm}0.3$ per week to once a day ($1.1{\pm}0.1$ per day). The number of patients who complained of abdominal pain was reduced from 15 (53.6%) to 4 (14.3%). Before hospitalization, nine patients underwent a CTT test, and 5 of 9 patients (55.6%) were classified as belonging to a group showing abnormalities. And in some patients, mild adverse effects were noted. We examined electrolytes and osmolality before and after disimpaction in 16 of 28 patients, and no abnormalities were noted. Conclusion: In terms of therapeutic efficacy and safety, combined oral and enema therapy using high-dose PEG 3350 with electrolytes is considered superior to conventional oral monotherapy or combined oral and enema therapy on an outpatient basis.