• Structural Engineering and Mechanics
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• 제74권3호
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• pp.351-363
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• 2020

Based on the dynamic tests of recycled aggregate concrete (RAC) short columns confined by the hoop reinforcement, the dynamic failure mechanism and the mechanical parameters related to the constitutive relation of confined recycled aggregate concrete (CRAC) were investigated thoroughly. The fracturing sections were relatively flat and smooth at higher strain rates rather than those at a quasi-static strain rate. With the increasing stirrup volume ratio, the crack mode is transited from splitting crack to slipping crack constrained with large transverse confinement. The compressive peak stress, peak strain, and ultimate strain increase with the increase of stirrup volume ratio, as well as the increasing strain rate. The dynamic confining increase factors of the compressive peak stress, peak strain, and ultimate strain increase by about 33%, 39%, and 103% when the volume ratio of hoop reinforcement is increased from 0 to 2%, but decrease by about 3.7%, 4.2%, and 9.1% when the stirrup spacing is increased from 20mm to 60mm, respectively. This sentence is rephrased as follows: When the stirrup volume ratios are up to 0.675%, and 2%, the contributions of the hoop confinement effect to the dynamic confining increase factors of the compressive peak strain and the compressive peak stress are greater than those of the strain rate effect, respectively. The dynamic confining increase factor (DCIF) models of the compressive peak stress, peak strain, and ultimate strain of CRAC are proposed in the paper. Through the confinement of the hoop reinforcement, the ductility of RAC, which is generally slightly lower than that of NAC, is significantly improved.

• 의학교육논단
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• 제15권1호
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• pp.46-53
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• 2013

The purpose of this study was to analyze the relationship among medical students' learning motivation, characteristics of multiple intelligence, and academic achievement. The participants were 144 medical students. The data were collected by administering learning motivation tests (self-confidence, self-efficacy, level of task, emotion of learning, learning behavior, failure tolerance, task difficulty, and academic self-efficacy), a multiple intelligence test (linguistic intelligence, logical-mathematical intelligence, musical intelligence, bodily-kinesthetic intelligence, spatial intelligence, interpersonal intelligence, intrapersonal intelligence, and naturalistic intelligence), and two semesters of grades. There is a correlation between multiple intelligences and learning motivation. Among academic self-efficacy of academic motivation, the self-control efficacy (0.28) and behavior (0.18) subscales are significantly positively correlated with academic achievement. However, the emotion subscale (-0.18) was significantly negatively correlated. Learning motivation was correlated with two of the eight multiple intelligence profiles: the intrapersonal intelligence (0.18) and bodily-kinesthetic intelligence (-0.19). The structural equation modeling analysis showed that the behavior and self-control efficacy subscales of intrapersonal intelligence had an impact on academic achievement. An analysis according to the academic achievement group showed significant differences in self-control efficacy and emotion subscales with intrapersonal intelligence. A positive relationship can be observed between learning motivation and some characteristics of multiple intelligence of medical school students. In light of the findings, it is worth examining whether we can control medical students' learning motivation through educational programs targeting self-control efficacy and intrapersonal intelligence.

• 한국안전학회지
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• 제34권5호
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• pp.7-14
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• 2019

The type III vessel, which is used to store high-pressure hydrogen gas, is made by wrapping the vessel's liner with carbon fiber composite materials for strength performance and lightening. The liner seals the internal gas and the composite resists the internal pressure. The properties of the fiber composite material depends on the angle and thickness of the fiber. Thus, engineers should consider these various design variables. However, it significantly increases the design cost due to the trial and error under designing based on experience or experiments. And, for aluminum liners, fatigue loads due to using and charging could give a huge impact on the performance of the structure. However, fatigue failure does not necessarily occur in the position under the highest load in use. Therefore, for hydrogen storage vessel, fatigue evaluation according to design patterns is essential because stress distribution varies depend on composite layer patterns. This study performed an optimization analysis and evaluated a high-pressure hydrogen storage vessel to minimize these trial and error and improve the reliability of the structure, while simultaneously conducting fatigue assessment of all patterns derived from the optimization analysis process. The results of this study are thought to be useful in the strength improvement and life design of composite reinforced high-pressure storage vessels.

• 항공우주시스템공학회지
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• 제14권3호
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• pp.60-68
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• 2020

항공기 엔진 내의 파손된 블레이드가 케이스를 관통하여 외부로 나가게 되면, 동체에 부딪혀 승객의 안전을 위협하게 된다. 따라서 엔진 케이스 설계 시 항공청의 안전성 평가 인증을 받아야한다. 본 논문에서는 국내의 독자적인 엔진 개발을 위해 필요한 엔진 케이스의 컨테인먼트 인증 요구조건과 개발 기술에 대하여 조사하였다. 미국과 유럽의 항공청에서 제시하는 컨테인먼트 안전성 요구 조건을 정리하고 이 인증에 부합하는 케이스의 파편 봉쇄를 검증하는 실험적/해석적 방법에 대하여 확인하였다. 컨테인먼트 케이스에 대한 최근의 연구를 분석하여 케이스 개발 시 검증 방법을 제시하고자 한다.

• 한국방재학회 논문집
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• 제11권3호
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• pp.191-200
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• 2011

제방의 붕괴로 인하여 인명 및 재산상의 막대한 피해가 발생한다. 제방의 붕괴는 월류 및 침식에 의한 붕괴가 대부분을 차지하고 있으나 이에 대한 분석이 제대로 이루어지지 않고 있다. 사행하천에서의 흐름특성은 하천제방과 관련하여 실용적인 관점에서 연구하여야 하는 하천 수리학에서는 중요한 주제이다. 사행하천에서는 회전방향이 교호적으로 바뀌는 나선형의 흐름(2차류)이 3차원적으로 발생하는 것으로 알려져 있다.. 이에 본 연구에서는 2차원 CCHE2D모형과 3차원 FLOW3D모형을 이용하여 하천 만곡부에서의 흐름특성을 분석하고자 하였다. 가상 하도에 대하여 수리모형 실험의 실측치와 비교하여 모형의 정확성과 안정성을 검증하였다. 그리고 모형의 적용성 검토를 위해 남강댐 하류에 대하여 만곡부의 흐름특성(유속분포 및 최대유속경로, 수위분포, 2차류 거동, 편수위, 전단응력 분포 등)을 분석하였다. 그 결과 하천 만곡부에서의 수리적 특성을 보다 정확하게 제시할 수 있었으며 하천의 제방 안정성 평가시 사행하천에 관한 수리적 특성을 효율적으로 활용하고자 한다.

• 융합보안논문지
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• 제21권1호
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• pp.25-31
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• 2021

본 연구의 목적은 코로나19 바이러스 유행 시기에 교대근무체계로 운영하는 보안관제센터를 무중단으로 유지하기 위한 연구 이다. 사이버 보안위협에 대응하는 보안관제 시설은 24시간 365일 실시간으로 운영해야 하는 필수 보안시설이며, 보안운영 및 관리적인 부분에서 매우 중요하다. 만약 감염병 유행, 시스템 장애, 물리적 영향 등 보안관제 시설이 폐쇄되거나 영향이 있는 경우 실시간 사이버 보안위협에 대응 할 수 없으며, 보안문제에 치명적이 될 수 있다. 최근 코로나19 바이러스 유행으로 인한 시설 폐쇄, 장마철로 인한 보안시스템 가용성 장애 등 보안관제 시설 운영을 할 수 없는 사례가 확인되고 있으며, 이 외에도 물리적 영향으로 보안관제 시설을 운영 할 수 없는 상황에 대한 대비가 필요하다. 본 논문에서는 보안관제 시설을 다중화 시설로 구성하여 폐쇄되는 상황 발생 시 무중단으로 운영 할 수 있는 방안을 제안한다.

• Journal of Preventive Medicine and Public Health
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• 제54권3호
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• pp.190-198
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• 2021

Objectives: Insufficient evidence exists regarding factors that affect screening adherence among people with a family history of diabetes, who comprise roughly half of all patients with diabetes. Therefore, we aimed to identify the determinants of diabetes screening adherence in adults with a family history of diabetes who had not yet been diagnosed with diabetes. Methods: This cross-sectional study was conducted at selected urban primary healthcare facilities in Tehran, Iran. The study population was clinically non-diabetic adults above 20 years of age with a family history of diabetes in at least 1 first-degree relative. All eligible people identified on randomly-selected days of the month were invited to join the study. Results: Among 408 participants, 128 (31.4%) had received a fasting blood glucose check during the last year. Using binary logistic regression, the independent predictors of screening adherence were knowledge of adverse effects of diabetes such as sexual disorders (odds ratio [OR], 3.05) and renal failure (OR, 2.73), the impact of family members' advice on receiving diabetes screening (OR, 2.03), recommendation from a healthcare provider to have a fasting blood glucose check (OR, 2.61), and intention to have a fasting blood glucose check within the next 6 months (OR, 2.85). Other variables that predicted screening adherence were age (OR, 1.05), job (being a housekeeper; OR, 3.39), and having a college degree (OR, 3.55). Conclusions: Knowledge of the adverse effects of diabetes, physicians' and healthcare providers' advice about the benefits of early disease detection, and family members' advice were independent predictors of screening adherence.

• Asian Spine Journal
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• 제12권6호
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• pp.1053-1059
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• 2018

Study Design: Retrospective review. Purpose: To detect the effect of cannulated (poly-axial head) and solid (mono-axial head) screws on the local kyphotic angle, vertebral body height, and superior and inferior angles between the screw and the rod in the surgical management of thoracolumbar fractures. Overview of Literature: Biomechanics studies showed that the ultimate load, yield strength, and cycles to failure were significantly lower with cannulated (poly-axial head) pedicle comparing to solid core (mono-axial head). Methods: The medical charts of patients with thoracolumbar fractures who underwent pedicle screw fixation with cannulated or solid pedicle screws were retrospectively reviewed; the subjects were followed up from January 2011 to December 2015. Results: Total 178 patients (average age, $36.1{\pm}12.4years$; men, 142 [84.3%]; women, 28 [15.7%]) with thoracolumbar fractures who underwent surgery and were followed up at Hamad Medical Corporation were classified, based on the screw type as those with cannulated screws and those with solid screws. The most commonly affected level was L1, followed by L2 and D12. Surgical correction of the local kyphotic angle was significantly different in the groups; however, there was no significant difference in the loss of correction of the local kyphotic angle of the groups. Surgical correction of the reduction in the vertebral body height showed statistical significance, while the average loss of correction in the reduction of the vertebral body height was not significantly different. The measurement of the angles made by the screws on the rods was not significantly different between the cannulated (poly-axial head) and solid (mono-axial head) screw groups. Conclusions: Solid screws were superior in terms of providing increased correction of the kyphotic angle and height of the fractured vertebra than the cannulated screws; however, no difference was noted between the screws in the maintenance of the superior and inferior angles of the screw with the rod.

• Advances in aircraft and spacecraft science
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• 제6권2호
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• pp.145-156
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• 2019

As the industrial desire for a step change in productivity within the manufacture of composite structures increases, so does the interest in Through-Thickness Reinforcement technologies. As manufacturers look to increase the production rate, whilst reducing cost, Through-Thickness Reinforcement technologies represent valid methods to reinforce structural joints, as well as providing a potential alternative to mechanical fastening and bolting. The use of tufting promises to resolve the typically low delamination resistance, which is necessary when it comes to creating intersections within complex composite structures. Emerging methods include the use of 3D woven connectors, and orthogonally intersecting fibre packs, with the components secured by the selective insertion of microfasteners in the form of tufts. Intersections of this type are prevalent in aeronautical applications, as a typical connection to be found in aircraft wing structures, and their intersections with the composite skin and other structural elements. The common practice is to create back-to-back composite "L's", or to utilise a machined metallic connector, mechanically fastened to the remainder of the structure. 3D woven connectors and selective Through-Thickness Reinforcement promise to increase the ultimate load that the structure can bear, whilst reducing manufacturing complexity, increasing the load carrying capability and facilitating the automated production of parts of the composite structure. This paper provides an overview of the currently available methods for creating intersections within composite structures and compares them to alternatives involving the use of 3D woven connectors, and the application of selective Through-Thickness Reinforcement for enhanced damage tolerance. The use of tufts is investigated, and their effect on the load carrying ability of the structure is examined. The results of mechanical tests are presented for each of the methods described, and their failure characteristics examined.

• 국제지역연구
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• 제13권2호
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• pp.789-812
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• 2009

논문은 아제르바이잔의 정체성을 형성해 온 역사적 문화적 원천을 페르시아, 투르크, 러시아의 영향이라는 측면에서 분석하여 그 복합적인 성격을 해명하고, 1991년의 독립 초기 그것이 아제르바이잔의 대외정책에 미친 영향과 그 귀결을 살펴보고자 한다. 오늘날의 세계에서 정체성은 사회적, 정치적, 경제적, 문화적 맥락에서 뿐만 아니라 복합적인 맥락에서 진행되는 다양한 변화 속에서 형성되고 표현된다. 이러한 정체성의 표출은 다원적인 환경에서 종종 배타적인 결과를 가져오기도 한다. 독립 이후 PFA 정부는 아제르바이잔의 풍부한 문화적 유산과 다면적인 정체성을 강조하기보다는 종족적 기원과 아제르바이잔의 터키성(Turkishness)을 강조하는 논리를 내세웠다. 국내적으로 볼 때, 종족 민족에 기반을 둔 대외정책은 소비에트 하에서 아제리 민족에 흡수되었던 아제르바이잔의 쿠르드인조차도 소외감과 배신감을 느꼈을 정도로 심각한 실패에 직면했다. 국제적으로 볼 때, PFA 정부의 대외정책은 러시아와 이란으로 하여금 등을 돌리게 만들었을 뿐만 아니라, 터키가 러시아와의 관계 악화를 우려함에 따라 터키에 대한 교섭력도 약화시켰다. 이에 따라, PFA 이후에 집권한 헤이다르 알리예프는 아제르바이잔 정체성의 네 가지 요소(페르시아적인 정체성, 투르크적인 정체성, 러시아적인 정체성, 아제르바이잔적인 정체성)를 모두 활용하여 대외정책의 방향을 결정하였던 것이다.